DOCUMENT RESUME

ED 115 468 SE 018 843

TITLE Radiological Defense. Textbook.INSTITUTION Defense Civil Preparedness Agency (DOD), Washington,

D.C.REPORT NO SM-11.2272PUB DATE Jun 74NOTE 201p.; For Training Purposes Only

EDRS PRICE MF-$0.76 HC-$10.78 Plus PostageDESCRIPTORS *Educational Programs; *Emergency Programs;

*Instructional Materials; *National Defense;Radiation; *Radiation Effects; Safety; ScienceEducation; Textbooks

IDENTIFIERS Department of Defense; DOD

'ABSTRACT-This textbook has been prepared under the direction

of the Defense Civil Preparedness Agency (DCPA) Staff College for useas a student reference manual in radiological defense (RADEF)courses. It provides much oLthe basic technical informationnecessary for a proper understanding of radiological defense andsummarizes RADEF planning and expected operations. This textbook isnot intended to provide RADEF operational procedures or direction forthe development of RADEF plans and organizations. Such guidance willbe found in other DCPA publications. Among the chapters are: (1) anIntroduction; (2) Basic Concepts of Nuclear Science; (3) Effects ofNuclear Weapons; (4) Nuclear Radiation Measurements; and (5)Radiological Monitoring Operations and Techniques. (LS)

***********************************************************************Documents acquired by ERIC include many informal unpublished

* materials not available from other sources. ERIC makes every effort ** to obtain the best copy available. Nevertheless, items of marginal *

* reproducibility are often encountered and this affects the quality *

* of the microfiche and hardcopy reproductions ERIC makes available* via the ERIC Document Reproduction Service (EDRS). EDRS is not* responsible for the quality of the original document. Reproductions *

* supplied by EDRS are the best that can be made from the original.***********************************************************************

U S DEPARTMENT OF HEALTH,EDUCATION L WELFARENATIONAL INSTITUTE OF

EDUCATIONTHIS DOCUMENT HAS BEEN REPROOuCE0 EXACTLY AS RECEIVED FROMTHE PERSON OR ORGANIZATION ORIGINATING IT P0iNTS OF VIEW OR OPIN,ONSSTATED DO NOT NECESSARLY REPRESENT OTFic,AC NATIONAL INSTITUTE OFEDUCATION POSITION OR POLicy

SM-1122-2

JUNE 1974

SCOPE OF INTEREST NOTICE

The ERIC Facility has assignedthis document for pose singto: I' 6:0,In our judgement, this documentis also of interest to the clearing-houses noted to the right, Index-ing should reflect their specialpoints of view.

S 111

DEFENSE Civil. PREPAREDNESS AGENCY

DEPARTMENT OF DEFENSE

FOR TRAINING PURPOSES ONLY

RADIOLOGICAL DEFENSE:

DEFENSE CIVIL PREPAREDNESS AGENCY DEPARTMENT OF DEFENSE

(Supersedes SM-11.22-2 dated JUNE 1968)

FOREWORD

This textbook has been prepared under the direction ofthe Defense Civil Preparedness Agency (DCPA) Staff Col-lege for use as a student reference manual in radiologicaldefense courses. It provides much of the basic technicalinformation necessary for a proper understanding of ra-diological defense and summarizes RADEF planning andexpected operations.

This textbook is not intended to provide RADEF opera-tional procedures or direction for the development ofRADEF plans and organizations. Such guidance will befound in other DCPA publications.

TABLE OF CONTENTSChapter

1 INTRODUCTION TO RADIOLOGICAL DEFENSEDiscusses the nature of the radiological threat and the measures beingtaken to counteract that threat.

2 BASIC CONCEPTS OF NUCLEAR SCIENCE 5

D;z2u,-,ses those factors in nuclear radiation physics which RADEFpersonnel should understand in order to carry out their responsibilitiesin the most effective manner.

3 EFFECTS OF NUCLEAR WEAPONS 25Describes how nuclear weapons differ in both degree and kind fromconventional explosive weapons, and what the effects of a nuclearexplosion:4re, both in sequence and nature.

4 NUCLEAR RADIATION MEASUREMENT 55deal with the radiological effects of nuclear explosions it is vital to be

are to detect and to measure harmful levels or rates of radiation. Thischapter describes the principles by which we are able to do this.

5 RADIOLOGICAL EQUIPMENT 69Describes those radiological detection and measurement instrumentsconstructed on the principles set forth in Chapter 4 which are availableto the radiological defense program.

6 RADIOACTIVE FALLOUT 81One of the principal effects of nuclear weapons is the production ofradioactive material which comes back to earth in the form of fallout.This chapter tells how fallout is formed, how it is distributed, how it is ahazard, and how its movement can be predicted.

7 EFFECTS OF NUCLEAR RADIATION EXPOSURE 97This chapter tells what happens to the human body when subjected toradiation at various levels, and why these biological effects occur.

8 EXPOSURE AND EXPOSURE RATE CALCULATIONS 117A central concept in dealing with nuclear radiation is the decrease inradiation levels of radioactive fission products with the passage of time.This chapter tells how this decrease or decay may be calculated undervarious conditions and by various methods.

9 RADIOLOGICAL MONITORING TECHNIQUES AND OPERATIONS 135Describes the objectives of radiological monitoring and how those objec-tives are achieved.

10 PROTECTION FROM RADIATION 142There are various kinds of radiation emitted from fallout. This chapterexplains what they are, how they differ, and by what means we mayprotect ourselves from them.

11 RADIOLOGICAL DECONTAMINATION 153Describes the general nature of radiological decontamination and theprinciples and phases of decontamination operations.

12 RADEF OPERATIONS 164Describes the role of RADEF at each level of operations.

Page

1

Chapter Page

13 RADEF PLANNING 168We all accept the need to look before we leap, but why is planning withits cost in money and manhours really of such crucial importance? Thischapter provides some answers to that question.

14 "PAPER PLANNING" OR REAL RADEF 179A plan can be just words or it can be a blueprint for action. Thedifference lies in the availability of certain skills and knowledge neces-sary to translate the plan into effective action. This chapter discusseswhat these are.GLOSSARY 185

vi

INTRODUCTION TO RADIOLOGICAL DEFENSE

A strong civil preparedness program isvital to this nation's security. Today, ev-ery citizen and officials at every level ofgovernment should be concerned with pre-paring for disasters of all kinds. This bookis primarily concerned with one such po-tential disaster; that of a nuclear attackon this country.

This chapter will show why civil prepar-edness is vital to our security by statingthe nature of the threat we face and therole that an effective preparedness pos-ture can play in our national response tothat threat. It will also define what wemean by "radiological defense" and willindicate how such defense is organized.Another objective of this chapter, ana per-haps the most important one, is to explainhow effective radiological defense requirestrained and dedicated personnel. We can-not develop a radiological defense capabil-ity unless we can count on all of our citi-zens to learn something of the nature ofnuclear radiation and to gain an under-standing of the measures that can betaken to defend against its effects shouldthis nation ever face nuclear attack.

THE NATURE OF THE THREAT

1.1 Any assumptions about a possiblenuclear attack upon the United States aredangerous since we can never be sureabout a potential enemy's objectives oreven specific capabilities. Studies made bythe Department of Defense and others forexercise purposes use attack patterns thatrepresent current estimates of weaponsize and total yield that could be deliveredon this country in an all out nuclear at-tack.

1.2 Specific attack patterns assumehundreds of nuclear weapons with manymillions of tons of TNT equivalent are

CHAPTER 1

dropped on a mixture of military, indus-trial and population targets as both sur-face and air bursts. The results vary, ofcourse, but the unmistakable;fact re-mains that millions of Americans would bekilled outright in any such attack by thedirect effects of blast and fire. The loca-tions at which weapons were detonatedwould suffer unprecedented physical dam-age and the fallout radiation from surfaceweapons would affect hundreds of Squaremiles in a downwind direction from thosebursts. Additional millions of casualtieswould be caused depending on the amountof fallout protection available in the af-fected areas. In one simulated attack inwhich 800 nuclear weapons of 3,500 mega-tons were assumed, there would be about97 million people killed either outright orwho died subsequently from the direct ef-fects or from fallout. Another 30 millionwould have been injured but would sur-vive while the remaining 67 million out ofa total population of 194 million would notbe affected.

1.3 Three things are worth notingabout this threat. They are:

First, there is no equivalent in humanexperience for the destructiveness ofmulti-megaton hydrogen weapons. It isworth remembering that all the bombingraids on Germany in World War II . . . byall the allied forces,-. . . together totalledbut one megaton.

Second, not only are the weapons in anew dimension of destruction, but the de:livery systems are now in a new dimensionof effectiveness. Unless an anti-missile-missile is developed that can not only hitan enemy missile, but hit it almost imme-diately after it leaves the launching pad,and further, can discriminate betweenmissile and decoy, the advantage in

1

modern strategic missile warfare seemscertain to remain with the attacker. Thisfactor, coupled with the enormous destruc-tiveness of modern weapons, places apremium on surprise.

Third, this hypothetical attack wouldproduce casualties to more than half ofour populat under the conditions thenprevailing. If the conditions were changedto the extent of providing an effective civilpreparedness program, the casualtieswould be reduced to 'a major degree.

NOTE

Our system_ of ethics is based upon thebelief that each individual life is pre-cious. This belief underlies all ourAmerican institutions. It is, in fact,the basic way we differ from systemsembracing totalitarianism, where theindividual is the servant of the State,rather than our system where govern-ments derive ". . . their just powersfrom the consent of the governed . . ."This central fact, which motivates thegovernment in working for civil pre-paredness, should not be obscured bystatistics dealing with millions of cas-ualties. "Megadeath" like "genocide"are words that spring from systems ofgovernment alien to our way of lifeand our system of right and wrong.Unfortunately, the grim facts of themissile age force us to consider theseterms, so hostile to our belief in thesupreme value of the individual.

THE ROLE OF CIVIL PREPAREDNESS AND'RADIOLOGICAL DEFENSE

1.4 The national defensive posture of anation incorporates, among other things,the concept of "Active" and "Passive" of-fensive and/or defensive capabilities. "Ac-tive" offensive and defensive capabilitiesinclude items such as a nation's militaryforces and arms, both conventional andnuclear, as well as any other capabilitywhich represents an "Active" resource forimplementing and maintaining an offen-sive or defensive posture. ICBM's, bomb-ers, naval ships, etc., represent obviousexamples of an "Active" capability. "Pas-sive" capabilities, however, are thoseitems lacking the visibility of a militaryforce, but which may contribute signifi-cantly to a nation's defensive capability.2

8

Civil preparedness is a prime example of a"Passive" capability.

1.5 The Strategic Arms LimitationTalks (SALT) were designed to effect abalance of power among the two primarynuclear powersthe United States andthe Soviet Union. The SALT negotiationswould basically effect this balance by plac-ing limitations or curbs upon the "Active"offensive and defensive capabilities of a

*nation. It then becomes apparent that,assuming the effectiveness of the SALTnegotiations, a nation with a strong'Pas-sive" defensive capability occupies a posi-tion of strength. Herein lies the impor-tance of civil preparedness and radiologi-cal defense.

1.6 Since the civil preparedness pro-gram is a vital element of a meaningful"Passive" defensive posture, it, is ex-tremely important that it be an effectiveelement with trained personnel ready toprovide an immediab response in a crisessituation. Thus, in terms of the recogniz-able nuclear threat, radiological defenseoccupies a very realistic and substantialrole within the United States civil prepar-edness program and within the total de-fensive posture of the nation.

RADIOLOGICAL DEFENSE

1.7 In evaluating the results of a hypo-thetical nuclear attack upon the UnitedStates, several means of protection mustbe utilized. Assuming that a crisis periodor period of marked increased interna-tional tension will probably preceed anactual attack, crisis evacuation procedurescan remove segments of the populationaway from probable high risk areas. Addi-tionally, to the extent that it is available,protection against blast and other directeffects should be taken by utilizing availa-ble shelters. Equally important, however,is the need in all defensive plans for pro-tection against nuclear fallout. Radiologi-cal defense maximizes this type of protec-tion.

1.8 Thus, radiological defense is an ex-tremely important element of civil prepar-edness. Radiological defense is defined as:

The Organized Effort ThroughDetection, Warning, and

Preventive and Remedial MeasuresTo Minimize the Effect of

Nuclear Radiationon People and Resources.

GENERAL RADIOLOGICAL DEFENSEREQUIREMENTS

1.9 Following are the requirements of asound radiological and civil preparednessprogram:

(a) A system of shelters, equipped andprovisioned to protect our population fromthe fallout effects of a nuclear attack.

(b) Organization and planning of emer-gency actions necessary to restore a func-tioning society.

THE IMPORTANCE OF SHELTERS

1.10 Sheltersboth individual andcommunityare "keys" for survival. Thisis because shelter plays a dual role in aneffective radiological defense program;first, as a shield protecting individuals;and second, as a shield protecting the per-sons' who, by possessing special knowledge,skills, and habits of organization, can com-bine to assure the continuing of a func-tioning, democratic society. Thus, a shel-ter is not only a passive shield; it is also anactive element in the system of counter-measures that would have to be taken toassure the survival of the nation after-anattack.

As radiation' levels decline,, people canleave their shelters to perform neededtasks of recovery. But when can theyleave their shelters? This and other ques-tions, such as determining what the radia-tion levels are within the shelter, can besatisfactorily answered in one way only:through accurate measurement or moni-toring.

MONITORING AND THE MONITORINGSYSTEM

1.11 To assure adequate measurementof radiation levels to support postattackradiological defense operations, the nation

needs a large number of fallout monitor-ing stations. Some of these stations maybe located within community shelters,since such shelters form strong points ofsurvival and bases of ultimate recoveryoperations. Those community sheltersthat provide for extended geographic andcommunications coverage are particularlysuited for serving in the additional capac-ity of monitoring stations.

1.12 Whether in separate monitoringstations or carrying out monitoring proce-dures from community shelters, the pri-mary job of the monitor will be to supplyinformation on radiation levels, informa-tion basic to survival and recovery opera-tions. In carrying out their duties, themonitors should receive technical direc-tion and supervision from their organiza-tional Radiological Defense Officer.

RADIOLOGICAL DEFENSEORGANIZATION

1.13 As stated in Public Law 85-606, itis the intent of Congress, in providingfunds for radiological defense, that theresponsibility for such defense be "vested ,jointly in the Federal Government and theseveral States and their political subdivi-sions." The division of responsibilitiesamong governments, which is a centralfeature of our Federal system, is fullyreflected in the organization of radiologi-cal defense. The DCPA recommended pro-gram describes in some detail the respon-sibility of each element and level of gov-ernment, and the organization establishedto give effect to these levels of responsibil-ity.

1.14 In order to make the radiologicaldefense program a success, there is needfor radiological monitoring stations atFederal, State, and local facilitiesthroughout the nation. This means thatthere is a need for money to pay for theinstruments and equipment required;there is need for management to assurethat these stations operate effectively andin one coordinated system. But there iseven more need for trained men andwomen who can operate the equipment, dothe other specific jobs needed, and provide

3

leadership in radiological defense matterson the local level. An essential part of suchlocal leadership is the training of RADEFpersonnel.

1.15 DCPA training courses are de-signed to produce a core of competent ra-diological defense personnel includingthose who will go back to their communi-ties and train others. For without trainedpeople, the best laid plans become littlemore than complicated dreams. Trained

4

1O

men and women breathe life into plans..This is the reason behind the organizationof DCPA courses. The courses offer thetraining. If that offering is takento thefullest potentialthen all the effort, andplanning, and hopes of those deeply con-cerned with protecting our society, fromthe President on down, will be realized.For on men and women like ourselves, inthe last analysis, will lie the success of theradiological defense program.

BASIC CONCEPTS OF NUCLEAR SCIENCE

We will begin by ending the mystery.Since the aim of this book is to help you inyour work of radiological defense, it isessential that you understand what youare defending againstnuclear radiation.

This, then, is the primary objective ofthis chapter:

Understanding Nuclear RadiationThere are many kinds of radiation, some

of which, such as long and short radiowaves, infrared (or heat) radiation, visible-light, and ultraviolet radiation are famil-iar to all of us. However, nuclear radia-tion, the noiseless, odorless, unseen, unfeltsomething that can be so deadly seems, asWinston Churchill said of Russia, "a riddlewrapped in mystery inside an enigma".

Fortunately, this need not be so. A fewconcentrated hours of study will quicklymake radiation understandable.

However, if our job were how to stop aircontamination from automobile exhausts,we would not get too far by confiningourselves to the nature of the exhaustalone. It would be necessary to study thefuel, the way the auto engine burned thefuel, as well as many other things. Onlythen could we understand, and possibilycope with, the factors in the exhaustfumes that were harmful.

The same need exists with nuclear ra-diation. If we are to understand it, wemust see the whole picture; we must knowthe why as well as the what of nuclearradiation.

Therefore, to help us understand nu-clear radiation, the major objective of thischapter, we must also have some grasp of:

WHAT is meant by "matter" and "en-ergy"

CHAPTER 2

WHAT are the kinds of nuclear radia-tion

WHAT is the language of nuclearphysics, the terms, signsand symbols used to de-scribe the world of the atomand radiation

WHAT is the structure of the atomWHAT is the nature of its partsHOW do these parts behaveHOW is nuclear radiation measured

TWO FUNDAMENTALS AND ABOMBSHELL

2.1 There are two physical laws that wemust understand before we talk about theatom.

2.2 The first of these is known as theLAW OF CONSERVATION OF MATTER.According to this law, the total mass of thematerial universe remains always thesame, regardless of all the rearrange-ments of its component parts. This wasfirst demonstrated by the brilliant Frenchphysicist Antoine Lavoisier, whose geniuswas cut short by the French Revolution.Lavoisier burned a candle of knownweight until it disappeared. He thenweighed the oxygen used by the burningcandle, the wax that remained and thefoul gas ;carbon dioxide) and water vaporformed by the burning candle. He foundthat the weight of the candle that disap-peared and the weight of the oxygen thatcombined with it equalled the weight ofthe carbon dioxide and water vapor. Thisis one demonstration of the LAW OF CON-SERVATION OF MATTER.

2.3 The second law of conventionalphysics is known as the LAW OF CON-SERVATION OF ENERGY. This law

1.1

5

states that one, form of energy Can beconverted to another form, but the totalamount of energy in the universe neitherincreases nor decreases.

2.4 Until 1905, matter or mass and en-ergy were looked at as separate entities,as indeed they appear to be.

2.5 Then, a young mathematician andphysicist working in the Swiss Patent Off-ice produced a bombshell. The young manwas Albert Einstein. He said, in what isprobably the most important mathemati-cal equation in history, that E equals mc2,or, in plain English, that there is an exactequivalence between mass and energy.Mass can be converted to energy and, evenmore strangely, energy can sometimes beconverted to mass.

2.6 According to Einstein, it is notmass or energy as a separate entity, butrather the total mass-energy of the uni-verse that remains constant. In his equa-tion E = mc2 E stands for energy, in ergs,generated by any reaction; m is for "mass"in grams, lost in any reaction; and c is thespeed of light, equivalent to 3 x 1010 cm persecond (186,000 miles per second).

6

NOTEt

As you read through this and otherchapters you may meet words and

1400TONS OF COAL

terms new or unclear to you, such as"ergs". All of these words are includedin the GLOSSARY found at the end ofthe text.

POWER IMPLICATIONS

2.7 Although no one has succeededthrough nuclear fission in converting toenergy more than a small fraction of anymass, the advantages of nuclear fissionover chemical power (such as combustion)are enormous. (See Figure 2.7 for someexamples). For instance, in the fission-ing of uranium, as in the bomb droppedover Hiroshima, only a minute part of thetotal mass of radioactive substance ischanged to energybut this release of en-ergy is gigantic. The Hiroshima blast wasequivalent to 20,000 tons of TNT. This wasproduced by the fission of 2.2 pounds ofuranium (since only a minute part of thetotal actually underwent fission, the ura-nium contained in the bomb was consider-ably more than 2.2 pounds). Why so littlemass can produce so much energy is pre-cisely what was explained in Einstein'sE =mc2 formula.

NATURE OF MATTER

2.8 About the year 1900 a chemist, ifasked to explain the material world in

FISSION OF ONEPOUND OF URANIUM

:e.

PRODUCES AS

MUCH ENERGY AS

COM9USTION OF

40,000,000CUSIC FEET OF NATURAL GAS

250,000GALLONS OF GASOLINE

FIGURE 2.7.Nuclear energy as compared with chemical energy.FIGURE 2.7Nuclear energy as compared with chemical energy.

12

non-technical language, would have spo-ken somewhat as follows, stressing certainfacts that are still valid and are still fun-damental to an understanding of more re-cent discoveries.

-2.9 - The -chemist mould-speak .of ELE-MENTS, of the ATOM, of MIXTURES andCOMPOUNDS, of ATOMIC WEIGHT andthe PERIODIC TABLE. Let us take theseone at a time.

2.10 Elements.All material is made upof one or more elements. These are sub-stances that cannot be broken down intoother and simpler substances by anychemical means. Our 1900 vintage chemistdid not know it, but you will see later, thatit is possible to cause both decompositionand production of certain elements bymeans of nuclear reactions. There are nowover 100 known basic materials or ele-ments such as iron, mercury, hydrogen,etc., that have been discovered and classi-fied. Some have never been found in anatural environment, but are manmade.

2.11 Iron, mercury, and hydrogenex-isting at normal temperatures as a solid, aliquid, and a gas respectivelyare typicalelements. By heating, a solid element canbe changed to a liquid and even to a gas.Conversely, by cooling, a gaseous elementcan be changed to a liquid and even to asolid.

2.12 The Atom.The smallest portion ofany element that shares the general char-acteristics of that element is called anATOM, which is a Greek word meaningINDIVISIBLE PARTICLE.

2.13 Mixtures.Elements may bemixed without necessarily undergoing anychemical change. For example, if finelypowdered iron and sulfur are stirred andshaken together, the result is a mixture.Even if it were possible to grind this mix-ture to atom-size particles, the iron atomsand the sulfur atoms would remain dis-tinct from each other.

2.14 Compounds.Under certain condi-tions, however, two or more elements canbe brought together in such a way thatthey unite chemically to form a compound.The resulting substance may differ widelyfrom any of Its component elements. For

1;3

example, drinking water is formed by thechemical union of two gases, hydrogen andoxygen; edible table salt is compoundedfrom a deadly gas, chlorine, and a poison-ous metal, sodium.

2.15 Whenever a compound is pro-duced, two or more atoms of the combiningelements join chemically to form the MOL-ECULE that is typical of tl- r>. compound.The molecule is the smallest unit thatshares the distinguishing characteristic ofa compound.

2.16 Atomic Weight.Hydrogen is thelightest element. Experiments have dem-onstrated that the oxygen atom is almostexactly 16 times as heavy as the hydrogenAtom. Chemists express this truth by say-ing that oxygen has an ATOMIC WEIGHTof 16. Through many experiments, theatomic weights of the remaining elementshave been found.

2.17 The Periodic Table.Figure 2.17 isa standard table of the elements. Theatomic number of each element appearsabove its chemical symbol. The verticalcolumns represent family groups. Allmembersfrom the lightest to heaviestof a family behave like one another informinf (or refusing to form) chemicalcompounds with other families.

2.18 While still essentially correct, thiscirca 1900 chemist's view of matter needsto be supplemented (but not entirely re-placed) by an analysis of the atom. In 1900,only a few advanced scientists had becomeconvinced that the atom is divisible afterall. This was a new idea, since the atom isvery small, having an overall diameter ofabout 10-' centimeters.

THE ATOM AND ITS BUILDING BLOCKS

2.19 Small as it is, the atom proved tobe composed of yet smaller particles. Infact, as shown in Figure 2.19a, it proved tobe mostly empty space, with the actualmatter contained in a central mass. Thenew knowledge of the nature of the atomhas added many terms to those known toour 1900 vintage chemist. Let us take afew of these terms and relate them tosome diagrams of the atom. The termsmost useful are NUCLEUS, ELEC-

7

TH

E P

ER

IOD

IC T

AB

LE

OF

TH

E E

LE

ME

NT

S

IA0

Peri

od 1

1 HI

IA

Gro

ups

IIIA

IVA

VA

VIA

VIT

A

VII

II

IBII

B

IIIB

IVB

VB

VIB

VII

B

2 He

Peri

od 2

3 Li

4 Be

5 B6 C

7 N8 0

9 F10 N

e

Peri

od 3

11 Na

12 Mg

13 Al

14 Si15 p

16 S17 C

I18 A

rr

Peri

od 4

1920

21 Sc22 T

i23 V

24 Cr

25 Mn

26 Fe27 C

o28 N

i29 C

u30 Z

n31 G

a32 G

e33 A

s,

Se35 B

r36 K

r

Peri

od 5

37 Rb

38 Sr39 Y

40 Zr

41 Nb

42 Mo

43 (TO

44 Ru

45 Rh

46 Pd47 A

g48 C

d49 In

50 Sn51 Sb

52 Te

53 I54 X

e

Peri

od 6

55 Cs

56 Ba

57-7

1L

anth

ani

des

72 HI

73 Ta

74 W

75 Re

76 Os

77 Ir78 Pt

79 Au

80 Hg

81,

T1

82 Pb83 B

i84 Po

'85 A

t86 R

n

Peri

od 7

87 Fr88 R

a

89-1

0A

cti

nide

s

104 () '

Lan

than

ide

5758

5960

6162

6364

6566

6768

6970

71Se

ries

La

Ce

PrN

d(P

m)

SmE

uG

dT

bD

YH

oE

rT

mY

bL

u

Act

inid

e89

9091

9293

9495

9697

9899

100

101

102

103

Seri

esA

cT

hPa

U(N

P)(P

u)(A

m)

(Cm

)(B

k)(C

O(E

s)(F

m)

(Md)

(--)

(Lw

)

Figu

re 2

.17

FIGURE 2.19a.If an atom were the size of the Em-pire State Building, its nucleus would be as largeas a pea and the electrons would revolve aroundthe nucleus at a distance of several hu,ndred feet.(Understanding that there is so much unoccupiedspace within the atom is important to an under-standing of the interaction of radiation with mat-ter.)

TRONS, PitOTONS and NEUTRONS, thelatter three comprising the basic atomicbuilding blocks as shown in detail in Fig-ure 2.19b.

2.20 The NUCLEUS is the heavy,dense core of the atom, containing practi-cally all of its weight. As we have seen,this nucleus is surrounded at quite some

UNIT SYMBOLS

WEIGHT OR RELATIVEMASS IN ATOMIC

MASS UNITS

RELATIVEELECTRICAL

CHARGE

PROTON o OR 1 007593 arm, .1 + I

NEUTRON n OR on, I 0009B orrio 0

ELECTRON

e OR e OR0 000549 emu I

AN ATOMIC

BILLIONTH

MASS UNIT (mu) IS EQUAL TO I ,10'24 GRAMS OR ONE

OF BILLIONTH OF MILLIONTH OF GRAM

FIGURE 2.19b.Atomic building blocks.

ELECTRON (4,11 Chop)

0 PROTON (Positive Chop)

6 NEUTRON (N COEN)

FIGURE 2.21.Elementary particles that make up anatom.

distance by ELECTRONS which whirlaround the nucleus at tremendous speeds.Electrons are very small and have practi-cally no weight.

2.21 If we examine the structure of thenucleus in greater detail, we see that itconsists of little individual balls of matterthat are about the same size in all atoms.Some of these little balls of matter have apositive electrical charge. These are calledPROTONS. Others, called ,NEUTRONS,have no electrical charge and are said tobe electrically neutral. Both a proton anda neutron are much larger and heavierthan an electron (see Figure 2.21).

2.22 For each positively charged PRO-TON in the nucleus, there is a negativelycharged electron in orbit around the nu-cleus. The number of protons in the nu-

I. HYDROGEN

3. LITHIUM

2. HELIUM

4. BERYLLIUM

FIGURE 2.22Comparing the atoms of the first fourelements.

cleus, therefore, determines the number ofelectrons which are in orbit around thenucleus. The number of protons also deter-mines the nature of the element. For exam-ple, the single positive charge on the hy-drogen nucleus balances the negativecharge on theelearo-n. Thus, in its normalor UNEXCITED state, the hydrogen atomas a whole is electrically neutral. The nextelement heavier than hydrogen is helium,and it has two electrons that move in asingle orbit. Two positive charges in thehelium nucleus counterbalance the nega-tive effect of the two electrons. Lithium,the next heavier element, has three elec--.,trons. Only two of these travel in thecomparatively small area near the nu-cleus, the third has a much larger orbit.The lithium nucleus, therefore, has threepositive charges. See Figure 2.22 for exam-ples.

2.23 If time and space permitted, theatoms of all the elements could be exam-ined one by one. For present purposes,however, the oxygen atom (Figure 2.23)will be an adequate example.

2.24 The oxygen atom has eight pro-tons, and therefore eight positive chargesin its nucleus. To balance these eight posi-tive charges, eight electrons are required.The first two electrons are in the innerorbit, as is normal in any atom abovehydrogen. Three outer orbits, contain theother three pairs of electrons, as shown in

ELECTRON (Negative Chose)

Q PROTON (Positive Charge)

NEUTRON (No Chores)

FIGURE 2.23.The oxygen atom.

the drawing. One way to think of the sixouter electrons, all revolving and spin-ning, is as if they were tracing a hollowshell like an ultra-light tennis ball. Scien-tists customarily speak of electrons asbeing located in SHELLS, classified as K,L, M, N, 0, P, A, and sub-shells, in accord-ance with their energy level, which is pro-portional to a distance from the nucleus.

2.25 Continuing with our detailed lookat the oxygen atom, we see that in addi-tion to the eight protons and the twoshells with a total of eight eleltrons, thereare also eight uncharged particles or neu-trons.

2.26 With the single exception of hydro-gen in its simplest form, all atomic nucleicontain neutrons as well as protons. Thelighter elements tend to have approxi-

THE SOLAR SYSTEM

FIGURE 2.24.Another way of viewing the atom is as a minute solar system. Instead of the sun at the center,there is the nucleus; instead of the planets in orbit, there are the electrons.

10

mately equal quotas of neutrons and pro-tons; the heavier elements have more neu-trons than protons. This fact, to be ex-plained in greater detail later, is impor-tant to an understanding of radiation.

ISOTOPES

2.27 The number of neutrons in thenucleus may range from zero to almost150. In certain elements it is found thatdifferent atoms of the same element havethe same number of protons but vary inthe number of neutrons. To the chemist,this iS of little concern because the chem-ist works with the orbital electrons, andsince all of these atoms have the samenumber of protons, they will have thesame number of electrons in orbit. Sincethey have a different number of neutronsin the nucleus, however, the various atomsof the same element will not all weigh thesame.

MASS. - -A measure of the quantity ofmatter

WEIGHT.A measure of the force withwhich matter is attracted tothe earth

2.28 To the nuclear physicist and physi-cal chemist, these are different forms -ofthe same chemical element differing onlyin the number of neutrons' in the nucleus.Many of the isotopes are stable. Some ofthe isotopes are unstable, and thereforeradioactive..

2.29 Figure 2.29 shows various isotopesof the element hydrogen. The heavier iso-topes make up a very small fraction of onepercent of the total amount of hydrogenfound in nature. Ordinary water consistsof molecules each of which is made up oftwo atoms of hydrogen and one atom ofoxygen. If water contains hydrogen whichis not the normal isotope of hydrogen (oneproton) but the deuterium isotope (oneproton and one neutron) it will look likeregular water, taste like regular water,and, from the chemical point of view, itwill be water. However, from a nuclearpoint of view, this is HEAVY WATERbecause it is made with the heavier iso-tope of hydrogen.

2.30 The third form of hydrogen called

'HYDROGENCOMMON

STABLE FORM

DEUTERIUMRARE

STABLE FORM

TRITIUMRARE

RADIOACTIVE FORM

FIGURE 2.29.Isotopes of the element hydrogen.

tritium contains one proton and two neu-trons in its nucleus. The addition of thesecond neutron to the nucleus produces anunbalance in the proton to neutron ratiothereby causing an unstable or excitedcondition due to the excess energy.. Thisexcess energy is emitted in the form ofradiation. Tritium is the only isotope ofhydrogen that is radioactive.

2.31 Only three isotopes of the elementhydrogen exist. Attempts to produce afourth isotope fail because the nucleus of atritium atom will not capture an addi-tional neutron.

2.32 Figure 2.32 shows two differentisotopes of uranium. One is called uranium238. Its nucleus contains 92 protons and146 neutrons which combined total 238particles. The other, uranium 235, con-tains 92 protons and 143 neutrons whichtotal 235 particles. Both of these will reactchemically in exactly the same way.Therefore, ,to the chemist they are thesame. The important difference to the nu-clear physicist is the fact that, althoughboth are radioactive, the U235 will sustaina chain reaction whereas the U238 will not.

2.33 As previously stated, the first ele-ment, hydrogen, has only three isotopes inits family. The number of isotopes for eachof the other elements varies considerably

11

with, for example, as many as 25 istotopesfor the fiftieth element, tin.

2.34 Altogether there are over 1,200isotopes, the majority of which are radio-active. Most elements have two or more-isotopes. While the number of neutrons inthe nucleus does not materially affectchemical behavior, the neutron to proton(n:p) ratio of the nucleus does affect theatom in other ways.

URANIUM235RADIOACTIVE

URANIUM238RADIOACTIVE

FIGURE 2.32.Isotopes of the element uranium.

12

FIGURE 2.39a.Atoms of the element hydrogen andthe element helium.

We are close to our main objective--understanding nuclear radiation!!!

2.35 Before the discovery of the neu-tron, scientists identified any element by aone-letter or-two-letter symbol represent-ing its chemical nameH for hydrogen, Clfor chlorine, Na for sodium (whose latin-ized technical name is natrium, hence theNa), and so on. The nuclear physicist ac-cepts these time-honored letter symbols;but when speaking in general terms, herefers to any of them as SYMBOL X.

2.36 To make precise reference to agiven atom, the nuclear physicist (1) pre-cedes symbol X with a numerical subscriptcalled SYMBOL Z and`(2) follows symbol Xwith a number (often, but not always,written as a superscript) called SYMBOLA. His identification of an atom, then,takes the form zX" or sometimes when Z isclearly understood, simply X" or XA. Forexample, U235 and U238.

2.37 SYMBOL Z.The subscript Z iscalled the ATOMIC NUMBER; it tells howmany protons the nucleus contains (andsimultaneously, of course how many pla-netary electrons the atom has in its nor-mal state). For hydrogen Z is 1; for oxygenit is 8; for uranium it is 92.

2.38 SYMBOL A.The final identifyingsymbol is an ATOMIC MASS NUMBERrepresenting the sum of the protons andthe neutrons.

18

SUBSTANCE SYMBOLPRO-TONS(V

ATOMICMASS

NUMBER(A)

NEU -TRONS(A- 2)

ELEC -TRONS

(.1)

HYDROGEN !HI I I 0

DEUTERIUMz

1H2 OR ID

TRITIUM

IN1 OR IT3 I 3 2 I

OXYGEN

80168 16 8 8

URANIUM92U238 92 238 146 92

FIGURE 2.39b.Symbol meanings.

IMPORTANT

To find the number of neutrons in anyfully identified atom, subtract Z fromA.

2.39 Let us see a few examples of theuses of these symbols. In Figure 2.39a, wesee an atom of hydrogen with the sub-script 1 as its atomic number (Z), sincehydrogen has only one proton, and super-script 1 as its atomic mass number (A),since the atom contains only the one pro-ton and no neutrons. The Z number- forhelium is two, since it has two protons inthe nucleus. As we have seen, each ele-ment has a distinctive atomic number rep-resenting the number of protons in thenucleus, and we can determine the num-ber of neutrons in the nucleus by subtract-ing the atomic number Z from the atomicmass number A. As examples, the nucleusof 9213239 contains 146 neutrons and thenucleus of 27C59 contains 32 neutrons. Sincenormal atoms are electrically neutral, eachatom will have the same number of elec-trons as there are protons in the nucleus,i.e., the Z number will equal the number ofprotons in the nucleus or the number ofelectrons in orbit about the nucleus. Thesubscript Z number is sometimes disre-garded because the atom is identified bychemical symbol. Thus He' or 2He4 bothhave the same meaning. Figure 2.39bshows how symbols are interpreted.

2.40 The ratio of neutrons to protonswithin the nucleus of the atom largelydetermines the stability of the atom. The

protons being positively charged tend torepel each other. The repulsive force iscounteracted, however, by a nuclear at-tractive force called Binding Energy. Verylittle is known of this energy. However, itis known that for elements which haverelath ely low atomic weights;-nuclear sta-bility occurs when the number of protonsand neutrons are nearly equal. Heavierelements, those with higher Z numbers,require a higher neutron to proton (n:p)ratio for stability. Whereas those elementsin the lower part of the periodic table(Figure 2.17) are stable when the isotopehas an n:p ratio of approximately one (ap-proximately the same number of neutronsas protons). The n:p ratio must increase asthe Z number increases if the stability ofthe atom is to be maintained. Beginningwith the element bismuth, atomic number83, when the n:p ratio increases above1.5:1 there are no stable isotopes. The sta-ble range of n:p ratios for many elementsis not critical, i.e., there are several ele-ments with many stable isotopes.,

2.41 An unstable atom, one with a n:pratio either too high or too low, will even-tually achieve stability by spontaneousemission of energy and/or particles fromits nucleus. This process is known as RA-DIOACTIVITY. It may be the natural de-cay of unstable isotopes which occur innature or it may be as the result of artifi-cial radioactivity which has been causedby man. In each case the nucleus is in anunstable or excited state, having an excess

Of energy which will be radiated allowingthe nucleus to achieve a stable or groundstate.

RADIOACTIVITY is the spontaneous disinte-gration of unstable nuclei with the result-ing emission of nuclear radiation.

19

2.42 Radiation is the conveyance of en-ergy through space. Everyone is familiarwith the radiation of heat from stoves,light from electric lights and the sun, andthe fact that some kind of energy is re-ceived by our radio and television sets tomake them operate. The radiation of en-ergy from radioactive materials is compa-

1 3

AN

GS

TR

OM

UN

IT -

A P

HY

SIC

AL

UN

IT O

FLE

NG

TH

, EQ

UA

L T

O 1

/108

CE

NT

IME

TE

RS

.

ELE

CT

RO

N V

OLT

- T

HE

AM

OU

NT

OF

EN

ER

GY

AC

QU

IRE

D B

Y A

N E

LEC

TR

ON

FA

LLIN

G T

HR

OU

GH

A P

OT

EN

TIA

L D

IFF

ER

EN

CE

OF

ON

E V

OLT

.

ELE

CT

RO

N V

OLT

AG

E (

V)

IS R

ELA

TE

D T

O T

HE

WA

VE

LEN

GT

H O

F R

AD

IAT

ION

(X

), IN

AN

GS

TR

OM

UN

ITS

, AP

PR

OX

IMA

TE

LY T

HU

SV

=12

420/

X

WA

VE

LEN

GT

H X

AN

GS

TR

OM

UN

ITS

101

710

1601

510

141o

13 1

012,

toll

WA

VE

LEN

GT

H A

ND

FR

EQ

UE

NC

Y A

RE

RE

LAT

ED

BY

: cX

v

C =

VE

LOC

ITY

OF

ELE

CT

RO

MA

GN

ET

IC W

AV

ES

= 3

x 1

010

CE

NT

IME

TE

RS

PE

R S

EC

ON

D

V -

FR

EQ

UE

NC

Y =

CY

CLE

S/S

EC

. = V

IBR

AT

ION

S P

ER

SE

CO

ND

= W

AV

ELE

NG

TH

IN C

EN

TIM

ET

ER

S

VIS

IBLE

SP

EC

TR

UM

LIM

ITS

4,00

0 A

NG

ST

RO

MS

8,00

0 A

NG

ST

RO

MS

7.5

1014

CY

CLE

S/S

EC

.3.

7 x

1014

CY

CLE

S/S

EC

.

tom

1o9

toe

t07

106

103

1o4

103

102

toI

to'

Ii

I

160

CY

CLE

S/S

EC

II

ELE

CT

RIC

1610

CY

CLE

S/S

EC

HE

RT

ZIA

N

-1-

CYCLES/SEC.

113

10 INF

RA

ULT

RA

1

PO

WE

R

IND

UC

TIO

N

RE

D

VIS

IBLE

(RA

DIO

,T

ELE

VIS

ION

,R

AD

AR

)V

IOLE

T

HE

AT

ING

II

11

gt

EN

ER

GY

1I

II

ELE

CT

RO

N V

OLT

S 1

0 12

K1"

10 1

010-

9 10

6I

IV

10-7

10 6

10

510

I-4

103

1010

1

I10

102

FIG

UR

E 2

.42.

Ele

ctro

mag

netic

spe

ctru

m.

102

IP

1810

CY

CLE

S/S

EC

.

GA

MM

AIN

GS

X-

RA

YS

-45

610

1010

1012

3

CY

CLE

S/S

EC

.

II

103

0410

8 10

810

7 10

8

CO

SM

IC--

a. T10

9to

'°

rable to these familiar forms of radiationbut, as indicated by Figure 2.42, are gener-ally higher in frequency and, therefore,represent greater energies.

...NOTE

Remember, radioactivity is a PROC-ESS. Nuclear radiation is the PROD-UCT of this process.

2.43 Atoms in the unbalanced state de-scribed in paragraph 2.41 are said to beRADIOACTIVE. They are spontaneouslyemitting some type of IONIZING radia-tion energy. IONIZATION is a processwhich results in the formation of electri-cally charged particles (IONS) from neu-tral/atoms or molecules.

2.44 For a closer look at ionization, con-sider Figure 2.44 in which a normal atomis subjected to a bombardment of energy.The energy of this bombardment mayknock an electron from its orbit into freespace, i.e., it will not be associated withany atom. It is a negatively charged parti-cle in space and is referred to as a NEGA-TIVE ION. The remainder of the atomfrom which the electron was dislodged isalso electrically unbalanced by this event.Having lost one electron with its negativecharge, it now has an effective net positivecharge of one since it now contains oneproton for which there is no counterbal-ancing electron. The positively chargedatom (or atoms) is known as a POSITIVE

ION. The two particles, the positive ion(atom or atoms) and the negative ion (dis-lodged electron) are known as an IONPAIR. The procss which caused this sepa-ration of particles making up the atom andthe attendant electrical unbalance is_known .as IONIZAT I ON.

PARNatMENG),

wasial*.

NEUTRAL ATMS NEGATIVEION

70/\.POSITIVE ION

FIGURE 2.44. 'Ionization.

2.45 Nuclear radiations are given off byatoms which have more than the normalcomplement of energy. The physicist saysthey are UNSTABLE. This unstable con-dition is often caused by too low or toohigh an n:p ratio as explained earlier.Radioactive atoms literally erupt fromtime to time emitting energy from thenucleus. These nuclear radiation emis-sions are classified as ALPHA PARTI-CLES, BETA PARTICLES and GAMMARAYS. Each type of radiation will be dis-cussed in more detail in later paragraphs.

IONIZINGRADIATION

(27 C. 51 + ---) 27 C04° + IONIZING RADIATION)

IONIZINGRADIATION

FIGURE 2.47.The normal atom of Co" bombarded by a neutron. In this case, the atom accepts this neutron inits nucleus "; the A number increases by one to Co" and the atom is radioactive.

2

15

2.46 Nuclear radiation differs fromother forms of radiation in the sense thatthe nucleus of an unstable atom containsan excess of energy which will be emittedregardless of man's efforts. Use of heat,chemicals_or pressure will not stop or alterthe, rate of nuclear .radiation .emissionsfrom a radioactive atom. Man can cause orstop other types of radiation such as heat,light, or even other atomic radiationswhich in many ways compare to nuclearradiation. In the case of heat and lightradiations caused by electricity, merelyflipping a switch can start or stop theseradiations.

2.47 Many nuclear radiations arecaused by bombarding atoms with energy,causing them to radiate energy whichceases whenever the bombardment stops.However, if the atoms in the material be-come radioactive as a result of the bom-bardment, they will then spontaneouslyemit ionizing radiation of one or moretypes until they reach a stable condition.One of the sources of nuclear radiationcommonly encountered in radiological de-fense training is 27Co" (Cobalt 60). Figure2.47 shows how this isotope of Cobalt isdeveloped from 27Co55.

2.48 Different radioactive elementsvary greatly in the frequency with whichtheir atoms erupt. Some radioactive mate-rials in which there are only infrequentemissions or radiations tend to have avery long life while those which are veryactive, radiating frequently, may have acomparatively short life. The time differ-ence is very great between short and longlived radioactive materials. Some sub-stances may stabilize themselves in asmall part of a second, while a radioactiveisotope with a long life may change ordecay only slightly in thousands or mil-lions of years. The rate of radioactive de-cay is usually measured in HALF-LIFE,the time required for the radioactivity of agiven amount of a particular material todecrease to half its original value.

100 200 me

me50

25 50INT HALF LIFE PERIODSTHE RADIATION LEVEL ISLESS THAN I.H.OF ITS

12.5 2 ORIGINAL INTENSITYr- ,`.,12.5

- 615_ _3.1221. 1566.25 -

HOURS 24 48 72 96 20 144 168GAYS I 2 3 4 5 6 7

FIGURE 2.49.Decay curve.

up to millions of years. The following ra-dioactive elements demonstrate this widerange of half-lives: argon 41,109 minutes;iodine 131, 8 days; radium 226, 1,620 years;plutonium 239, 24,000 years. Figure 2.49depicts a gamma emitting material with a24-hour half-life. This material when firstmade radioactive has a quantity of radio-activity of 200 millicuries. In 24 hours theradioactivity would be down to 100 millicu-ries; in another 24 hours it would be downto 50; in another 24 hours it would be downto 25, etc.

AFTER34,000MORE YEARS

PROTACTINIUM

rZ. I 21

AFTER34,000YEARS ..

.AFTER34,000MORE YEARS.

2.49 The half-life of a radioactive mate-rial may range from fractions of a second FIGURE 2.50.Another view of half-life.

16

22

2.50 Let us look at another example.Assume that the block shown at the upperleft in Figure 2.50 is composed entirely ofthe radioactive protactinium isotopeknown as Pan'. The half-life of this partic-ular isotope is 34,000 years. At the end Of34;000 years, therefore,. half of the-originalprotactinium atoms will have undergonetransmutation to other elements. The restwill still be protactinium. If they wereseparated from the transmuted atoms, theprotactinilm atoms would now constitutethe second block in Figure 2.50.

2.51 The second block will not decaycompletely in the second 34,000 year pe-riod. Unquestionably, it has only half asmany atoms as the original block; but bythat very fact it offers only half the origi-nal opportunity for atomic reactions totake place. As before, half of the atoms (aquarter of the original protactinium at-oms) will remain unchanged at the end ofthe second half-life.

2.52 During the third half-life, thenumber of protactinium atoms will againbe cut in half----and so on. In generalterms, then "x" grams of any radioactiveisotope will .decay in accordance with thefollowing series:

;+:+:+;56+-x3-41E44-112(8+2;6_Lx

2.53 No matter how far this series isextended, its final term, x/n will representonly half of the protactinium atoms thatwere intact at the beginning of the givenhalf-life. If x/n atoms have been lost dur-ing the preceding half-life through decay,an equal number still remain to start thenext half-life.

2.54 In other words, the sum of thisseries approaches x, the original numberof atoms, but (in theory at least) neverquite reaches it. There is always a frac-tion, equal to x/n, representing the atomsthat are still intact.

2.55 A useful rule of thumb is that thepassage of 7 half-lives will reduce the ra-dioactivity to a little less than 1 percent of

23

its original activity, and in 10 half-livesthe activity will be down to less than 0.1percent. The shorter the half-life, the morehighly radioactive the material will be.

2.56 As we will see in more detail insubsequent chapters, half-life has impor-tant bearings on safety. It is obvious, firstof all, that any isotope with a long half-lifeis potentially dangerous if it is produced inlarge amounts. When such an isotope isonce formedwhether by nature or in anatomic power plant or during a nuclearexplosionit will contaminate its sur-roundings for a long time to come.

2.57 For some of the artificially pro-duced radioactive isotopes, the half-life ismeasured in hours, minutes, or even sec-onds. These isotopes are extremely active;that is why they decay so fast.

COMMON TYPES OF NUCLEARRADIATION

2.58 There are three common types ofnuclear radiation with which you mustbecome familiar: ALPHA and BETA PAR-TICLES, and GAMMA RAYS.

2.59 Alpha Radiations emitted by ra-dioactive materials are often called alpharadiation or simply alpha. Alpha particlesare comparatively large, heavy particles ofmatter which have been ejected from thenucleus of a radioactive material withvery high velocity. The velocity withwhich these particles leave the nucleusdetermines the distance (range) that theywill travel in any substance. As indicatedin Figure 2.59, an alpha particle carries anet positive electrical charge of two andan atomic mass of 4.00277. Thus the alphaparticle is equal to the nucleus of a heliumatom which contains two protons (with onepositive charge each) and two neutrons.However, when we compare the speed ofalpha to that of beta and gamma, we findthis to be a relatively slow rate as mightbe expected due to alpha's size and weight.Alpha rays are literally small pieces ofmatter traveling through space at speeds

17

of 2,000 to 20,000 miles per second. When aradioactive atom decays by emitting analpha particle, transmutation of this atomto an atom of lower atomic number (Z) andlower atomic mass number (A) occurs.

04IOft Svill QS I ,2 TONoCT SSwrs

ELECINICLnil ITC 02 (a3(a3 S

C 11TsCLE 00277 +010(a PCL TO KCI,LatTON ST1*(0 Of ITS(L CC I NOTTS

at a AMITCLE 00004 KTETT ToCC. TO N.G.,

01210 CLIC T.O.

414 4. V0(e01 NOW NONEEL IC Te014+1 TC EvtOf 251461.

FIGURE 2.59.Characteristics of nuclear radiation.

2.60 Beta Particles are identical tohighspeed electrons. They carry a nega-tive electrical charge of one and are ex-tremely light, traveling at speeds nearlyequal to the speed of light, 186,000 milesper second. Although the atomic nucleusdoes not contain free electrons, only pro-tons and neutrons, the electrons which areemitted as beta particles result from thespontaneous conversion of a neutron intoa proton and an electron. The neutronwhich lost or emitted the beta particle hasbecome a proton with a positive chargeand thus the atom has been changed.Transmutation has produced an atom witha higher Z number.

2.61 Gamma Rays are a type of elec-tromagnetic radiation which travel withthe speed of light. As indicated in Figure2.59, they have no measurable mass orelectrical charge. We have become accus-tomed to the use of X-rays in the medicalfield. X-rays and gamma rays are similar,but there are two important differencesbetween them. First, as indicated in Fig-ure 2.42, while there is some overlapping,gamma rays are generally of a higherfrequency. The basic difference, however,is their source. Gamma rays originate inthe nucleus while X-rays originate in thecloud of electrons about the nucleus. Theemission of an alpha or beta particle fromthe nucleus of an atom as shown in Figure2.61, almost invariably leaves the nucleuswith an excess of energy (excited state)and will be accompanied by the emission ofgamma rays to reach ground or stablecondition.

18

2.62 The neutron is another type of ra-diation which accompanies certain typesof nuclear reactions but is not encoun-tered in natural radioactive decay. As wasdiscussed previously, this type radiation is

2 4

0

1111102

FIGURE 2.61, Excited to stable nucleus.

pable to induce radioactivity in stable iso-topes.

RADIOACTIVE DECAY AND DAUGHTERPRODUCTS

2.63 Radioactive decay, often results in"transmutations ", i.e., the Change of oneelement into another and the dream of themedieval alchemists. Some radioisotopesdecay directly to a stable state -in onetransmutation. Others decay through aseries of transmutations or steps formingdifferent radioactive elements calledDAUGHTER PRODUCTS' before finallyreaching a stable state.

2.64 Consider now what happens whena radioactive isotope emits radiation, andfollow one atom of uranium through itssuccessive transmutations. Starting withan atom of uranium 238, which has 92protons and 146 neutrons, follow thetransmutations in Figure 2.64.

2.65a Uranium 238 emits an alpha par-ticle. An alpha particle consists of twoprotons and two neutrons, and therefore isan atomic nucleus in its own right. It isthe nucleus of the helium atom. (Heliumhas a nucleus composed of two protons andtwo neutrons.) With the alpha particleemitted, there are now 90 protons and 144neutrons. The nucleus now weighs 234

ELEMENT ANDATOMIC WEIGHT

TYPE OFRADIATION EMITTED

NUMBER OF

PROTONS NEUTRONS

URANIUM- 238 92 146ALPHA PARTICLE -2 -2

THORIUM- 234 90 144BETA PARTICLE +I -I

PROTACTINIUM- 234 91 143BETA PARTICLE +I -I

URANIUM -234 92 142

ALPHA PARTICLE -2 -2THORIUM-230 90 40

ALPHA PARTICLE -2 -2RADIUM- 2 26 IS 138

ALPHA PARTICLE -2 -2RADON-2 2 2 66 136

ALPHA PARTICLE -2 -2

POLONIUM- 218 84 134ALPHA PARTICLE -2 -2

LEAD-214 82 132BETA PARTICLE +1 -I

BISMUTH- 214 83 131

BETA PARTICLE +I -IPOLONIUM- 214 84 130

ALPHA PARTICLE -2 -2

LEAD-210 82 126BETA PARTICLE +1 -I

BISMUTH -210 83 127SETA PARTICLE +1 -I

POLONIUM-210 84 126ALPHA PARTICLE -2 -2

L EAD- 206 STABLE ATOM 82 124

FIGURE 2.64.The decay chain of a uranium atom.

units; and since the number of protons hasbeen changed, it is no longer uranium butis, in fact, thorium 234.

2.65b Thorium 234 emits not an alphaparticle but a beta particle. Where doesthe beta particle come from? Rememberthat a neutron is electrically neutral. Wehave seen that an electrically neutralstate can be reached when positive andnegative charges balance one another andthat a neutron can act like a proton withan electron tightly tied onto it as shown inFigure 2.65b.

2.65c The negative charge of the elec-tron balances the positive charge of theproton resulting in a neutron. When thisnegatively charge electron is ejected as abeta particle the remainder is no longerelectrically neutral, but now has a positivecharge, thu's changing a neutron to a pro-ton. In effect, one proton has been gainedand one neutron has been lost. Now thereare 91 protons and 143 neutrons. Theweight is still 234, but since the number ofprotons has been changed, the nature ofthe element has been changed, and is nowan atom of prdtactinium 234.

2.65d Protactinium 234 also emits abeta particle so 1 proton is added, and 1neutron is subtracted, leaving 92 protonsand 142 neutrons. Its weight is 234, butthe element is, of course, again uraniumbecause it now has 92 protons.

2.65e Uranium 234 emits an alpha par-ticle, 2 neutrons and 2 protons are sub-tracted, leaving 230 particles in the nu-cleus. Since the number of protons is backto 90, the element is now thorium 230.

2.65f Thorium 230 emits an alpha parti-cle. Subtract 2 protons and 2 neutrons. Itnow has a weight of 226, and since it has

FIGURE 2.65b.Concept of a neutron changing into aproton by emitting a beta particle.

2i)

19

only 88 protons in the nucleus, it is theelement radium.

2.65g Radium emits an alpha particle,so 2 neutrons and 2 protons are lost leav-ing 86 protons and 136 neutrons. Our ele-ment is now radon 222 which is a gas.

2.65h Radon- 222- emits. a-n -alpha -parti-cle, leaving 84 protons and 134 neutrons.Again a different element is formedpo-lonium 218.

2.65i Polonium emits an alpha particle,which leaves 82 protons and 132 neutrons,and is lead 214.

2.65j Lead 214 emits a beta particlewhich increases the number of protons by1 and decreases the number of neutronsby 1, leaving 83 protons and 131 neutrons.This forms bismuth 214.

2.65k Bismuth 214 emits a beta particlewhich adds 1 proton and subtracts 1 neu-tron, leaving 84 protons and 130 neutrons.This is polonium 214.

2.651 Polonium 214 emits an alpha par-ticle which takes away 2 neutrons and 2protons, leaving 82 protons and 128 neu-trons for a mass of 210, and the element islead 210.

2.65m Lead 210 emits a beta particle,leaving 83 protons and 127 neutrons,which now becomes bismuth 210.

2.65n Bismuth 210 emits a beta particlewhich adds a proton and subtracts a neu-tron, leaving 84 protons and 126 neutrons.This is polonium 210.

2.65o Polonium 210 emits an alpha,which leaves 82 protons and 124 neutrons.The total weight is 206; the element is lead206.

2.65p Lead 206 is stable and not radio-active, therefore, this is "the end of theline".

2.66 Well, that's fine, and all very inter-esting, and accounts for beta and alpharadiation, but what about gamma radia-tion? Where does that come from? As wesaw in paragraph 2.61, gamma radiationoriginates when the discharge of one ofthese particles from a nucleus does nottake sufficient energy along with it toleave the nucleus in quite a contentedstate. If the particle leaving the nucleus

20

2-

does not take with it all of the energy thatthe atom would like to get rid of in thisparticular disintegration, it throws offsome of the energy in the form of gammaradiation. Therefore gamma radiation canbe given off by many radioactive Materialsin addition to the beta or alpha radiation.

2.67 The foregoing makes it clear whygamma radiation occurs and can thereforebe detected from a radium dial wristwatch or from uranium ore by a prospec-tor. Both radium and uranium are purealpha emitters, but as time passes thedecay process goes on and forms daughterproducts in the radium and uranium. It isfrom the decay of these various radioac-tive "daughter products" that the gammaradiation is given off. Pure radium or ura-nium, freshly prepared, represents only analpha hazard and could safely be handledwith the bare hands as far as externalhazard is concerned. (Handling it with thebare hands is not a good idea because ofthe possibility of introducing some radiuminto the body by this means and, besides,heavy metals are toxic.) After the passageof time, however, the daughter productsstart to build up and alpha, beta, andgamma radiation are all being given offfrom the radium and its associated daugh-ters.

INTERACTION OF RADIATION WITHMATTER

NOTE

The important thing to rememberabout nuclear radiation is that it is a"shooting out" of particles or bits ofenergy, some large, some small; somefast, some slow; some weak, some pow-erful. Since everything contains at-omsincluding our bones, skin, andorgans, of coursethese particlesstrike the atoms with force, the amountdepending on the kind of particle, andother factors. Actually, since the atomis, as we have seen, made up of anextremely compact core and shells ofelectron(s), these electrons bear thebrunt of the hammering given outwhen the atom is struck by particles.As will be seen, the electrons react tothis hammering in various ways. Thishas great significance to the study of

radiation safety and the effects of ra-diation on the body, as you will dis-cover later.

2.68 Alpha particles lose their energyrapidly and hence have a limited range,only about 6 or 7 centimeters in air, andare completely stopped by a sheet of pa-per. When the alpha particle is stopped,stabilized, or reaches ground state, it haspicked up two electrons which are availa-ble in space thus making it a neutral he-lium atom. The loss of energy by the alphaparicle as it traverses space is due to itshigh specific ionization, i:e., the number ofion pairs produced per centimeter of path.Each ionization event in air requiresabout 32-36 ELECTRON VOLTS per ionpair produced. The unit electron volt is theamount of energy acquired by a unitcharge of electricity when the chargemoves through a potential difference ofone volt. For example, if an electronshould start at a potential of zero voltsand be accelerated to a point having apotential of 32 volts, it would acquire anenergy equivalent to 32 electron volts. Anelectron volt is a very small amount ofenergy. More common terms are thousandelectron volts (keV), and million electronvolts (MeV).

2.69 The high specific ionization of al-pha particles, 20,000-80,000 ion pairs percentimeter of air traversed, is due to sev-eral factors. First, alpha is a relativelylarge particle and has a high positivecharge; hence it will not only collide withother matter, but there will be frequentelectrostatic interactions with the elec-trons associated with the atoms throughwhich the particle is passing. These inter-actions result in a loss of energy by liter-ally knocking an electron from its orbit(ionization), or it may lose energy to theatom by merely displacing electrons fromtheir normal orbits without ejecting themfrom the atom (excitation). Figure 2.69shows the difference between an excitedatom and a positive ion.

2.70 In addition to being large and posi-tively charged, the alpha particle is alsocomparatively slow, and by remaining inthe vicinity of the atoms in its path, there

ELLC1,10110rS16ED 10 100111 000.1

.,1L( CIACTOOM

ExCITED ATOM

POSITIVE ION

FIGURE 2.69.Excitation and ionization by an alphaparticle.

is a greater probability of ionizing them.With this loss of energy there is a reduc-iion in speed and hence a steadily increas-ing amount of ionization, at first slowlyand then more rapidly, reaching a maxi-mum and then dropping sharply almost tozero. Figure 2.70 is a representative curvefor the specific ionization of alpha parti-cles. The range and specific ionization var-ies somewhat for different radioactive iso-topes due to variation in the energy withwhich the alpha particle is ejected, 4.0MeV to 10.6 MeV. However, all alpha parti-cles emitted in a specific nuclear reactionhave essentially the same energy, and sothe same range.

2.71 The beta particle does not lose itsenergy as rapidly as the alpha particle.This is due to the fact that it is a. verysmall particle, has less charge than the

it

0

5000

4000

3000

2000

1000

02

DISTANCEIIN CENTimETENSI

FIGURE 2.70.Specific ionization of alpha particles.

21

alpha particle, and is moving at a higherrate of speed. An alpha particle, because ofits relatively heavy weight, is not easilydeflected and tends to travel in a straightpath causing a high degree of ionization. Abeta particle, being lightweight is easilybounced around in any material. There-fore, its range in terms of distance fromthe point of origin to the point where itfinally associates itself with an atom mayvary considerably. The actual distancetraveled by the beta particle also varies toa considerable extent but not as much asthe measurement from the point of originto the point where complete loss of excessenergy occurs. Unlike alpha, the beta par-ticles emitted by any given nucleus have arange of velocities and only mean or maxi-

, mum energies, can be assigned to primarybeta particles. Tables almost invariablyshow maximum energies.

2.72 The range of velocities for betaparticles ranges from about 25 to 99 per-cent of the speed of light, with correspond-ing energy variations from 0.025 MeV to3.15 MeV with a majority of them being inthe vicinity of 1 MeV. The range of thebeta particle is proportional to its energy.Therefore, a 3 MeV beta particle willtravel further than a 1 MeV beta particle.

2.73 Range is only approximately in-versely proportional to the density of theabsorbing material through which itpasses, i.e., the more dense, the higher theZ number, the more effective that mate-rial will be in stopping beta particles. How-ever, because of the emission of X-rayswhen beta particles react with high Znumber materials, low Z number mate-rials such as aluminum, glass and plasticsare normally used as beta shields.

2,74 The specific ionization of beta par-ticles is approximately 50-500 ion pairs percentimeter in air varying according to theenergy of the beta particle and the densityof the absorbing material. The range ofbeta particles in air would be several me-ters. Thus, compared to the few-centime-ter range of alpha in air, beta has a longrange.

2.75 Gamma rays do not consist of par-ticles, have no mass, travel at the speed oflight and hence do not lose their energy as22

2 8

RADIATIONRANGEIN AIR SPEEDS

spEEIFICLOMEATIOPP

ALPSA 5-7cm 2.000-20.000PMI/SEC

20.000-40.000.. moron

SETA 200-000 HP 25- 99%SPEED OF LIGHT

50-500.en mwt/crn

GAMMAUSE OF HALF-

TINCKNESSSPEED OF UGIV46.000 Ytt/SEC

S -9...a/cln

FIGURE 2.74.Characteristics of nuclear radiation.

rapidly as either alpha or beta particles.Gamma rays or photons produce no directionization by collision as alpha and betabecause' gamma 'rays' have no mass. Theyare absorbed or lose their energy by threeprocesses known as the PHOTOELEC-TRIC EFFECT, the COMPTON EFFECT,and PAIR PRODUCTION.

2.76 Gamma rays are highly penetrat-ing, their effective range depending ontheir energy. The effect of air on a eammaray is so small that it is nu practical tomeasure the range of gamma radiation interms of inches, feet, or meters, but itspenetrating power is measured in terms ofthe amount of material that will be re-quired to reduce the gamma ray to somefraction of its original value.

2,77 As a gamma ray or photon passesthrough an atomit may transfer all of itsenergy to an orbital electron ejecting it

PAPER

1.1. 0 a a 8 eFIGURE 2.76.PenetrIPation-absorption of nuclear

radiation.

from the atom. If the photon carries moreenergy than necessry to remove the elec-tron from its orbit, this excess energy canbe transferred to the electron in, the formof kinetic energy. Figure 2.77 shows elec-trons ejected in this manner. These arereferred to as PHOTOELECTRONS, andthe process by which this transfer of en-ergy was accomplished is known as thePHOTOELECTRIC EFFECT. Since theorbital electron in this case nas completelyabsorbed the energy of the gamma ray,the photon disappears. The photoelectronwill ultimately. lose its energy through theformation of ion pairs. The photoelectriceffect generally occurs with low energygamma photons of approximately one-tenth MeV or less.

PHOTON ENERGY

ELECTRON

FIGURE 2.77.Absorption of gamma radiation by thephotoelectric effect.

2.78 The COMPTON EFFECT does notcompletely absorb the energy of thegamma ray. A gamma ray loses a part ofits energy to a free or loosely bound or-bital electron but will continue as a scat-tered gamma photon of lower energy. Theenergy of this photon will equal the differ-ence in original energy less the amount ofenergy transferred to the electron. Thegamma photon reacting with an orbitalelectron acts as though it had mass sinceit causes the electron to be ejected withhigh energy and a lower energy photonrebounds at some angle. Both the electronwhich is ejected at an angle to the path ofthe original gamma photon andthe lowerenergy gamma photon which is also scat-tered at an angle may cause further ioni-zation. Figure 2.78 shows the Comptoneffect. This effect occurs with interrnedi-

2

ate gamma photons of approximately one-tenth to one MeV.

PHOTON ENERGY

LOWERENERGY PHOTON

COMPTONELECTRON

FIGURE 2.78.Absorption of gamma radiation by theCompton effect.

2.79 PAIR PRODUCTION occurs onlywith high-energy gamma rays. In thisprocess, as the photon approaches the nu-cleus of the absorbing atom, it completelyconverts itself into a pair of electrons. Oneof these is called a NEGATRON but ac-tually is an ordinary electron with a nega-tive charge. The other particle which hasexactly the same mass as the negatron(electron) but carries a positive chargerather than a negative charge is known asa POSITRON and is designated by thesymbol e+. This process requires gammarays with a minimum energy of 1.02 MeV,and at energy levels above this the possi-bility of this interaction increases. Figure2.79 is a diagram of this reaction.

INCIDENT PHOTON \

FIGURE 2.79.Absorption of gamma radiation by pairproduction.

2.80 Energy in excess of 1.02 MeV isshared by the negatron-positron pair inthe form of kinetic energy. The positronusually acquires somewhat more energythan the negatron. This process is oftenused as an example of Einstein's mass-energy theory (E = mc2, see paragraph 2.5),since it is an example of the creation ofmatter (the pair of electrons) out of pureenergy (the gamma ray). It has been found

23

that the mass of one electron is equal to0.51 MeV. Since the pair production proc-ess involves the conversion of energy to anegatron-positron pair, the energy re-quired must be at least two times theenergy equivalent of one, electron, 0.51MeV. Any energy in the photon that is inexcess of 1.02 MeV causes the ejected par-ticles to have greater kinetic energy. Thenegatron is now equal to the beta particle,usually a very energetic beta particle, andwill react and be stabilized in the samemanner as previously explained. The posi-tron has an extremely short life, which isended by combining with an electron.However, before this happens it will causeionization of other atoms. When the posi-tron does join an electron they are annihi-lated with the production of two gammaphotons of 0.51 MeV each, which eventu-ally will be absorbed by Compton or pho-toelectric effect.

CURIES AND ROENTGENS

To be effective in your radiologicaldefense work, you must get a firmgrasp on the ways radiation is meas-ured. "Radiation", like "distance" is ageneral concept. You would have aweak understanding of distance if youwere vague about "foot", "inch","mile", "kilometer", "light year" andthe other ways by which distance ismeasured. The same is true for radia-tion.

2.81 The CURIE (Ci) is the unit used tomeasure the activity of all radioactive sub-stances. It is a measurement of rate ofdecay or nuclear disintegration that oc-curs within the radioactive material. Thecurie initially established the activity(that is, the decay rate) of radium as thestandard with which the activity of anyother substance was compared.

2.82 By using a formula that takes intoaccount the number of atoms per gramand the value of the half-life in seconds,scientists have determined that the activ-ity of radium is equal to 3.7 x 101° nucleardisintegrations per gram per second. Thisvalue is now the standard unit of compari-sbn. A curie of any radioactive isotope,

24

3l)

therefore, is the amount of that isotope thatwill produce 3.7 X 1010 nuclear disintegra-tions per second. Since the measure isbased on number of disintegrations, theweight of the radioisotope will vary fromthat of radium. A curie of pure Co6° wouldweigh less than 0.9 milligrams, while acurie of U238 would require over two metrictons. The curie is a relatively large unit.In training, a millicurie, mCi (one-thou-sarfdth curie) and the microcurie, MCi(one-millionth curie) are common units inuse. At the opposite extreme, the curie istoo small a unit for convenient measure-ment of the high-order activity producedby a nuclear explosion. For this purpose,the megacurie (one million curies) is used.

2.83 The ROENTGEN (R) by definitionmeasures exposure to gamma and X-rays.It is an expression of the ability of gammaor X-ray radiation to ionize air. One R willproduce 2.083 x 109 ion pairs per cubic cen-timeter of air or 1.61 x 1012 ion pairs pergram of air. (See Par 4.13 for a morecomplete discussion.)

The curie measures radioactivity.The roentgen measures X or gammaradiation.

REFERENCES

The Effects of Nuclear Weapons.Glas-toneSupuel,_1964. Prepared by the U. S.epartriient of Defense, and published by

the U. S. Atomic Energy Commission April1962; Revised Edition Reprinted February1964. (For sale by Superintendent of Docu-ments, U. S. Government Printing Office,Washington, D.C. 20402. Price $3.00, withcalculator $4.00.)

Explaining the Atom.Hecht, Selig, Ex-plorer Books Edition, Viking Press, Inc.,1964.

Nuclear Radiation Physics.Lapp,Ralph E. and Andrews, Howard L., Pren-tice-Hall, Inc., 1972.

Sourcebook on Atomic Energy.Glas-stone, Samuel, D. Van Nostrand Company,Inc., 1967.

Radiological Health Handbook.PublicHealth Service, January 1970.

EFFECTS OF NUCLEAR WEAPONS

After our introduction to the languageof nuclear physics, we are ready to usesome of these terms in arriving at anunderstanding of a nuclear detonation anda knowledge of what can be expected froma nuclear detonation. This is our primaryobjective and in reaching it, we will alsocover:

WHAT' is a ehaiii reactionWHEN does it occurHOW is it like a chemical explosionHOW is it differentWHAT is fission and fusionHOW a nuclear weapon worksWHAT are the effects of a nuclear

explosionWHAT is fallout

FAMILIARITY BREEDS CONTROL

3.1 During World War II many largecities in England, Germany, and Japanwere subjected to terrific attacks by high-explosive and incendiary bombs. Beforethe war, it was fully expected that suchattacks would cause great panic amongthe civilian residents of bombed cities. Ob-servations during the attacks and subse-quent detailed studies, however, fail tobear out this expectation. The studiesshowed that when proper steps were takenfor the protection of the civilian popula-tion and for the restoration of servicesafter the bombing, there was little, if any,evidence of panic. In fact, when suchmeasures are taken, the studies showedthat there was a definite decline in overtfear reactions as the air bombings contin-ued, even when the raids become heavierand more destructive.

3.2 The history of nuclear defense may

31'

CHAPTER 3

be said to have started with the explosionof the two bombs over Japan in August,1945.

These, the first and only nuclear weap-ons ever used against an enemy, causedunprecedented casualties. Many of thesecasualties could have been prevented ifthere had been sufficient warnings to per-mit clearing the streets, and if the peopleof Hiroshima and Nagasaki had knownwhat to expect and what to do. For exam-ple, only 400 people out of a population ofalmost a quarter of a million were insidethe excellent tunnel shelters at Nagasakithat could well have protected 75,000 peo-ple.

3.3 Information accumulated at Alamo-gordo, Hiroshima, Nagasaki, Bikini, En-iewetok, and Nevada, as well as experi-ence gained from other types of warfare,has contributed to the store of defensiveknowledge. From this knowledge, methodsof coping with a nuclear weapon attackhave been, and are being devised.

NUCLEAR WEAPON DETONATION VS.HIGH EXPLOSIVE DETONATION

3.4 The nuclear bomb was designed asa blast weapon. Therefore, although im-mensely more powerful, it resemblesbombs of the conventional type, insofar asits destructive effect is due mainly to theblast or shock that follows the detonation.However, nuclear detonations do differfrom conventional detonations in four im-portant respects:

Firsta fairly large amount of .theenergy from a nuclear detonation isemitted as THERMAL RADIATION,generally referred to as LIGHT andHEAT;

Secondthe explosion is accompaniedby highly-penetrating, harmful but IN-

25

VISIBLE NUCLEAR RADIATIONS;Thirdthe nuclear reaction PROD-

UCTS, which remain after the detona-tion, are RADIOACTIVE, emitting ra-diations capable of producing harmfulconsequences in living organisms;Fourthnuclear explosions can hemany thousands (or millions) of timesmore powerful than the largest conven-tional detonations.

PRINCIPLES OF A CHEMICALDETONATION

3.5 Before the discovery of how nuclearenergy could be released for destructivepurposes, the explosive material in bombsof the type in general use, often referredto as conventional bombs, consistedlargely of atoms of the elements carbon,nitrogen, hydrogen, and oxygen, in TNT(trinitrotoluene) or of a related chemicalmaterial. These explosive substances areunstable in nature, and are easily brokenup into more stable molecules. This proc-ess is associated with the liberation of arelatively large amount of energy, mainlyas heat. Once the decomposition of a fewmolecules of TNT is initiated, by means ofa suitable detonator, the resulting shockcauses still more molecules to decompose.As a result, the overall rate at which TNTmolecules break up is very high. This typeof behavior is characteristic of many ex-plosions, the process being accompaniedby the liberation of a large quantity ofenergy in a very short period of timewithin a limited space.

3.6 The products of the decompositionof conventional explosives are mainly ni-trogen and oxides of nitrogen, oxides ofcarbon, water vapor, and solids, notablycarbon, which are readily dissipated in thesurrounding air. Therefore, the sub-stances remaining after tne explosion dono more harm than the poisonous carbonmonoxide present in the exhaust gaseswhen automobile and airplane engines areoperated in the'open air.

3.7 With a conventional explosive thechemical molecules comprising the variousatoms are held together by certain forces,sometimes referred to as valence bonds.When the molecules undergo decomposi-

26

tion, there is a rearrangement of the e.t-oms, and there is a change in the charac-ter of the valence bonds. As stated above,a chemical explosive is an unstable com-pound, and in it the valensce forces arerelatively weak. In the molecules of thedecomposition products, however, thesame atoms are bound more strongly. It isa law of physics that the conversion of anysystem in which the constituents are heldtogether by weak forces into one in whichthe forces are stronger, must be accom-panied by the release of energy. Conse-quently, the decomposition of an unstablechemical explosive results in the libera-tion of energy.

PRINCIPLES OF NUCLEAR DETONATIONS

3.8 An atomic or nuclear explosion re-sembles chemical explosions in the respectthat it is due to the rapid release of a largeamount of energy. But the difference liesin the fact that in the nuclear explosion,the energy results from rearrangementwithin the central portion, or nucleus ofthe atom, rather than among the atomsthemselves as in a chemical explosion.Since the forces existing between the pro-tons and neutrons in the nucleus are muchgreater than the forces between the atomsin a molecule of chemical explosive mate-rial, energy changes, accompanying nu-clear rearrangements are very muchgreater than those associated with chemi-cal reactions.

3.9 The basic requirement for energyrelease is that the total mass of the inter-acting species should be greater than thatof the resultant product (or products) ofthe reaction. As we saw in Chapter II,there is a definite equivalence betweenmass and energy. Thus, when a decreaseof mass occurs in a nuclear reaction, there.s an accompanying release of a certainro-nount of energy related to the decrease

mass. In addition to the necessity fortile nuclear process to be one in whicht:iere is a net decrease in mass, the releaseof nuclear energy in amounts sufficient tocause an explosion requires that the reac-tion should be able to reproduce itself onceit has been started. Two types of nuclear

U255 NUCLEUS

FISSION FRAGMENTSPLUS

ENERGY,

FISSION

HELIUM NUCLEUSPLUS

ENERGY

FUSION

FIGURE 3.9.Fission and fusion.

interactions which can meet the require-ments for the production of large amountsof energy in a short time are FISSION andFUSION. The fission process takes placewith some of the heaviest nuclei (highatomic number), whereas the fusion proc-ess involves some of the lightest nuclei(low atomic number). (See Figure 3.9.)

NUCLEAR FISSION

3.10 The fissile materials which canpresently be used to produce nuclear ex-plosions are the uranium isotopes U233,

U235, and the plutonium isotope Pu239.

When a neutron enters the nucleus of theappropriate atom, the nucleus splits (fis-sions) into two daughter nuclei and two tothree neutrons (Figure 3,10). For U233, U235,

and Pu23y, unlike the case for U238, there isno lower limit for the kinetic energy that aneutron must possess to enable it to causefission on capture by a nucleus of any ofthese three isotopes. For this reason,these isotopes are called fissile materials,and only these three are of practical sig-nificance. In the case of a nonfissile nu-cleus, the energy of the incident neutronmust exceed a certain threshold value toenable it to cause fission or-capture. Thethreshold values for U238 and Th232 (Thor-

33

ium 232) are nearly 0.9 MeV and 1.1 MeVrespectively. Generally speaking, anyheavy nucleus can undergo fission if theexcitation energy is large enough, e.g.,fission of gold occurs with neutrons of'about 100 MeV energy.

< FISSION FRAGMENT

I,n + " + 2 .5 f% (AVERAGE I 4. ENERGY

FISSION FRAGMENT

FIGURE 3.10.Fission of uranium 235 producesneutrons.

FISSION CHAIN REACTION

3.11 In addition to the large amount ofenergy released in nuclear fission, the sec-ond important fact, which has made possi-ble the production of an explosion as aresult of fission, is that the process isaccompanied by the release of two or moreNEUTRONS (Figure 3.10). The neutronsthus liberated in the fission process areable to cause the fission of other uraniumor plutonium nuclei. In each case moreneutrons are released, which can producefurther fission, and so on. Hence, a singleneutron could start a self - sustained' chainof fissions, the number of nuclei involvedincreasing at a tremendous rate.

3.12 Actually, not all the neutrons lib-erated in the fission process are availablefor causing more fissions. Some of theseneutrons escape and others are lost innon-fission reactions. It will be assumed,however, for simplicity, that for each ura-nium (or plutonium) nucleus undergoingfission, there are two neutrons producedcapable of initiating further fission. Sup-pose a single neutron is captured by anucleus in a quantity of uranium, so thatfission occurs. Two neutrons are then lib-

A self-sustained chain reaction in pure IP" or pure Th" or naturaluranium is not possible.

27

erated and these cause two more nuclei toundergo fission. This results in the produc-tion of four neutrons available for fis-sion. The fissions increase by geometricprogression (1,2,4,8,16,32,64,128,256, -512,1024,2048,4096, and so on). By theeighty-first step of this process, we have2.5 x 1024 fissionsenough to fission a kilo-gram of refined uranium. The time re-quired for the 81 steps is 'hog seconds. Asyou can see, this tremendous activitytakes place almost instantaneously, thusproducing an explosive reaction.

3.13 The actual loss of mass in the fis-sion of uranium or plutonium is only aboutone-tenth of a percent of the total. That is,if all the atomic nuclei in one pound ofuranium or plutonium undergo fission, the,decrease of mass would be roughly five-tenths of a gram or one-sixtieth part of anounce. Nevertheless, the amount of energyreleased by the disappearance of thisquantity of matter would be about thesame as that produced by the explosion of8,000 tons of TNT.

CRITICAL SIZE OF NUCLEAR FISSIONBOMB

3.14 When a piece of fissile material isbelow E certain size, a few of the atoms arecontinually undergoing fission, but moreneutrons escape through its surface thanare produced in fission, and an increasingchain of fissions is not built up. Such amass is called SUBCRITICAL. On theother hand, when a mass (in a givenshape) is just great enough to support asustaining chain reaction, it is called aCRITICAL mass. As we can readily see,

28

(BEFORE DETONATION)

HIGH EXPLOSIVE

TAMPER MATIRIAL

AC TIVC MATERI AL

FIGURE 3.14.Tamper

then, if several pieces of fissile material,totalling more than the critical amount,are suddenly brought together inside astrong container or TAMPER (see Figure3.14) a nuclear detonation results.

What constitues a CRITICAL mass de-, 4

de-pends upon a number of factors, includingthe density of the material (whether solidmetal or in porous, spongy form); and ahoupon the nature of the TAMPER andwhether it absorbs neutrons or can reflectthem back into the fissile charge.

3.15 Published information suggeststhat an unconfined sphere-of U235 metal ofabout 6'/2 inches diameter and weighingabait 48 kilograms would be a criticalamount; this would be reduced to about41/2 inches diameter (16 kg.) for a U235sphere enclosed in a heavy tamper (Figpre3.14). The critical sizes for U2" and Pu239have not been disclosed. The increasingmechanical complication of bringing to-gether, rapidly and simultaneously, anumber of subcritical pieces of fissile ma-terial, sets a practical limit to the power ofnuclear fission weapons. Another impor-tant consideration is that the size Of apurely fission-type bomb is limited be-cause, above a certain critical size, a lumpof fissile material is self-destructive.

(AFTER DETONATION)

NORMAL DENSITYSUBCRITICAL

ACTIVEMATERIAL

HIGH DENSITYSUPERCRITICAL

FIGURE 3.16a. Implosion principle.

3 4

PROPELLANT ACTIVE MATERIALEACH TWO THIRDS CRITICAL)

TAMPER

GUN TUBE

(BEFORE DETONATION)

FIGURE 3.16b.Gun assembly principle.

3.16 As we have seen, subcritical mas-ses or pieces of fissile material, whenbrought together rapidly can, underproper conditions, cause a chain reactionand subsequent explosion. As a very nec-essary safety precaution, it is obvious thatthe masses of fissionable material presentin a nuclear bomb must be kept subcriticaluntil time for the bomb to be detonated.And when that time arrives, the subcriti-cal masses must form a supercritical massinstantaneously. One way of producing asupercritical mass is. by forcing two ormore subcritical masses together. Anotherway is to squeeze a subcritical masstightly into a new shape and/or a greaterdensity. Such a mass becomes supercriti-cal without the addition of any more sub-stance. This latter method, first used in acrude form in the Nagasaki bomb, is calledthe implosion principle (Figure 3.16a). Inthis bomb, a given amount of fissile mate-

suberiticalin the form of a thin spher-ical became critical when com-pressed into a solid sphere. This compres-sion was brought about by firing speciallyfabricated shapes of ordinary high explo-sive arranged spherically on the outsidesurface of the hollow sphere. When theexplosive is detonated, the mass is com-pressed, immediately becoming supercriti-cal and the atomic detonation takes place.The other method was used with the Hiro-shima bomb. The subcritical masses, en-closed in something like a gun barrel, wereimpelled against each other by the actionof regular chemical explosives (Figure3.16b).

35

TAMPER

FISSION AND FUSION . . . ANDTHERMONUCLEAR WEAPONS

3.17 A fission explosion producesbriefly and in a small spaceintensities oflight and heat comparable to those in thesun. A fusion explosion does still more: itduplicates a part of the actual process bywhich the sun and other stars producetheir light and heat. This process is not achemical burning reaction. It is a nuclearfusion reaction in which four nuclei ofsimple hydrogen become one nucleus ofstable helium, with a conversion of massto radiant energy. Through this processour sun, every second, loses about 4 to 5million tons of matter, radiated as energy.From experiments made in laboratorieswith cyclotrons and similar devices, it wasconcluded that man could partially dupli-cate the process of the sun, by the fusionof isotopes of hydrogen. This element isknown to exist in three isotopic forms inwhich the nuclei have masses of 1, 2, and3, respectively. These are generally re-ferred to as hydrogen (H'), deuterium (H2or D2), and tritium (H3 or T3). Several dif-ferent fusion reactions have been ob-served among the nuclei of the three hy-drogen isotopes, involving either two simi-lar or two different nuclei. In order tomake these reactions occur to an apprecia-ble extent, the nuclei must have highenergies. One way in which this energycan 'be supplied is by means of a charged-particle accelerator, such as a cyclotron,as mentioned earlier. Another possibilityis to raise the temperature to very high

29

levels. In these circumstances, the fusionprocesses are referred to as "thermonu-clear reactions".

3.18 Temperatures of the *order of amillion degrees are necessary in order tomake the nuclear fusion reactions takeplace. The only known way in which suchtemperature can be obtained on earth isby means of a fission explosion. At temper-atures of millions of degrees centigrade,atoms are stripped of most of their sur-rounding cloud of electrons and the nucleimove at very high speeds experiencingmany collisions with one another. Underthese circumstances, the nuclei of therarer hydrogen isotopes deuterium andtritium have enough energy of motion toovercome the repulsive forces betweentheir single positive electrical charges andthey are able to fuse together. The energyreleased in the fusion of these two nucleiis about one-twelfth of that released in thefission of a single U235 nucleus; but on anequal weight basis, the fusion energy isabout three times as large as the energy offission of U235. The actual quantity of en-ergy liberated, for a given mass of mate-rial, depends on the particular isotope (orisotopes) involved in the nuclear fusionreaction. Four thermonuclear fusion reac-tions are noted below:

H2 +H2 --)11e3 +n +3.25 MeV

H2 +H2 --)11' +H3 +4.03 MeV

H3 +112 *He +n +17.58 MeV

H3 +H3 410 +2n +11.32 MeV

where He is the symbol for helium and n(mass = 1) represents a neutron. The en-ergy liberated in each case is expressed inmillion-electron-volts (MeV).

3.19 Used alone, deuterium and trit-ium, as isotopes of the gaseous elementhydrogen, have to be liquefied at a verylow temperature and maintained there forcontainment in a thermonuclear device.This is inconvenient although it has beenreported that the first American thermon-uclear device tested in 1952 was of this

30

SELF-SUSTAINED FISSIONOF PLUTONIUM 239

ON URANIUM 235

(LI. n. N. M' 4 II so)

THERMO-NUCLEARREACTION

01' /I' 17G MO

FIGURE 3.19.Fission-fusion reaction.

type. In later weapons the deuterium iscombined chemically with the metal lith-ium in the form of a white powder. Eachneutron (1 mass unit) released by the trig-gering fission bomb splits a lithium atom(6 mass units) into the non-radioactive gashelium (4 mass units) and tritium (3 massunits), and the latter fuses with the deu-terium atoms present in the compound(Figure 3.19). There is no limit, other thanthe convenience of delivery, to the size of afusion or thermonuclear weapon, and it isclaimed that lithium deuteride is lesscostly than fissile materials such as U233,U235 or PU239.

3.20 In considering weapon designs, itis possible *also to have a fission-fusion-fission type weapon (Figure 3.20). In theprocess of fusion, a neutron is released ata very high speed and it has enough en-ergy to split the commoner atoms of U238.A thermonuclear weapon can be designedwith a core of fissile U235 as a fusion initia-

33

1SELF-SUSTAINED FISSIONOF URANIUM 235

ILIA + + 4 111 W )

THERMO-NUCLEAR H. M4.. n' IT 111444

REACTION

FISSION OF URANIUM 238

FIGURE 3.20.Fission-fusion-fission reaction.

for encased in a heavy container of U2".This LP" casing will undergo fission fromthe high-speed neutrons produced in thehydrogen fusion detonation. Since the cas-ing might be many times heavier than thefissile core of U235, correspondingly larger=quantities of fission' products would be re-leased as fallout from such a weapon.

3.21 A much more detailed discussionof fission products will be taken up later inthis chapter, but it might be mentionedhere that all existing types of nuclearweapons release fission products. "Dirty"bombs produce a great deal and "clean"bombs produce little, the dirtiness depend-ing upon the ratio of fission to fusionenergy produced by the bomb. The divid-ing line between "clean" and "dirty"bombs is, thus, a matter of opinion, but thefission-fusion-fission type of weapon men-tioned in paragraph 3.20 would be a rela-tively "dirty" one.

ENERGY YIELD OF A NUCLEAREXPLOSION

3.22 The power of a nuclear detonationis expressed in terms of the total amountof energy released as compared with theenergy liberated by TNT when it explodes.A 1-kiloton nuclear detonation is onewhich releases energy equivalent to 1,000tons of TNT which is called the kiloton(KT). The advent of thermonuclear hydro-gen bombs made it desirable to use a unitabout 1,000 times larger still, and the me-gaton (MT) unit, was adopted. It is equiva-lent to the energy released by the detona-tion of 1,000,000 tons of TNT. The bombsdetonated over Hiroshima and Nagasaki,and those used in the 1946 test at Bikini,released roughly the same amount of en-ergy as 20,000 tons (or 20 kilotons) of TNT.In recent years, much more powerfulweapons, with energy yields high in themegaton range, have been developed.

DISTRIBUTION OF ENERGY

3.23 Although the detonation of chemi-cal explosives, such as TNT, and the deto-

, nation of a nuclear weapon both produce

heat or thermal radiation, the proportionas well as the quantity is much higher inthe case of the nuclear weapon. The basicreason for this difference is that, weightfor weight, the energy produced in a nu-clear explosion is millions of times as greatas that in a chemical explosion. Conse-quently, the temperatures reached in thenuclear explosion are much higher than ina chemical explosiontens of millions ofdegrees in a nuclear explosion comparedwith a few thousands in a chemical explo-sion.

3.24 For a nuclear detonation in theatmosphere below 100,000 feet, about 85percent of the total energy appears first asintense heat. As shown in Figure 3.24,almost immediately a considerable part ofthis heat 7:s converted to blast or shock;the remaining thermal energy moves radi-ally outward at the speed of light as heatand visible light. The remaining 15 per-cent of the energy of the nuclear explosionis released as various nuclear radiations.Of this, 5 percent constitutes the nuclearradiation produced within a minute or soof explosion, whereas the final 10 percentof the bomb energy is in the form of resid-ual radiation emitted over a period oftime. The residual radiation, includes theFALLOUT. we will discuss in later chap-ters. \

TYPES AND HEIGHTS OF NUCLEARDETONATIONS

3.25 As we have seen, an explosion is4-sf

the release of a large quantity of energy ina short interval of time within a limited

111141101*12% , 7

C04.0CL.C14

NDi110It

NA01.10,4

FIGURE 3.24.Distribution of energy in a typical airburst of a fission weapon in air at an altitude below10,000 feet.

3 i31

space. The liberation of this energy is ac-companied by a considerable increase intemperature, so that the products of theexplosion become extremely hot gases.These gases, at high temperature andpressure, move outward rapidly. In doingso, they push away the surrounding me-diumair, earth, or waterwith greatforce, thus causing the destructive (blastor shock) effects of the explosion. The term"blast" is generally used for the effect inair, because it resembles (and is accom-panied by) a very strong wind. In water orunder the ground, however, the effect isreferred to as "shock" because it is like asudden impact.

3.26 The immediate phenomena associ-ated with a nuclear explosion, as well asthe effects of shock and blast, and thermaland nuclear radiation, vary with the loca-tion of the point of burst in relation to thesurface of the earth. For each weapon ofspecific power, there is a critical height ofburst above which the fireball will nottouch the ground and, hence, it will notproduce .appreciable contamination on theearth's surface. Although many variationsand intermediate situations can arise inpractice, for descriptive purposes threetypes of bursts are distinguished. Themain types, which will be defined below,are air, surface, and sub-surface burst.

CHARACTERISTICS OF AN AIR BURST

3.27 An air burst (frequently the mostefficient means of accomplishing a mili-tary objective, and the type used overJapan) is defined as one in which the bombis exploded in the air, above land or water,at such a height that the fireball (at maxi-mum brilliance) does not touch the sur-face. The aspects of an air burst will bedependent upon the actual height of theexplosion, as well as upon the energy yieldof the weapon, but the general phenomenaare much the same in all cases.

3.28 In the following discussion, it willbe supposed first, that the weapon detona-tion takes place in the air at a considera-ble height above the surface. The descrip-tions given here refer mainly to the phe-nomena accompanying the explosion of a

32

38

1-megaton TNT equivalent nuclear bomb.The important aspects of a nuclear explo-sion in the air are summarized in Figures3.28a to 3.28e.

THE FIREBALL

3.29 As already seen, nuclear reactionsinvolving fission and fusion in a nuclearweapon lead to the liberation of a largeamount of energy in a very short period oftime within a limited space. As a result,the nuclear reaction products, bomb cas-ing,' other weapon parts, and surroundingair are raised to extremely high tempera-tures, approaching those in the center ofthe sun. Due to the great heat produced bythe nuclear explosion, all the materialsare converted into the gaseous form. Sincethe gases, at the instant of explosion, arerestricted to the region' occupied by theoriginal constituents in the bomb, tremen-dous pressure- will be produced. Thesepressures are many hundreds of thou-sands times the atmospheric pressure,'i.e., of the order of millions of pounds persquare inch.

3.30 Within a fraction of a second of thedetonation of the bomb, the intensely hotgases at extremely high pressure appearas a roughly spherical, highly luminousmass. This is the fireball referred tc inparagraph 3.26. A typical fireball accompa-nying an air burst is shown in Figure3.28a. Although the brightness decreaseswith time, after about a millisecond,' thefireball of a 1-megaton nuclear bomb ex-plosion would appear to an observer 60miles away to be many times as bright asthe sun at noon.

3.31 As a general rule, the luminosityof the fireball does not vary greatly withthe yield (or power) of the bomb. The sur-face temperatures attained, upon whichthe brightness depends, are thus not verydifferent, in spite of differences in thetotal amounts of energy released.

3.32 Immediately after its formation,the fireball begins to enlarge in size, en-gulfing cooler surrounding air. The growth

The normal atmospheric pressure at sea level in 14.7 pounds persquare inch (PSI).

A millisecond is onethousandth part of a second.

in size of the fireball is accompanied by adecrease in temperature (and pressure)and, hence, in luminosity. At the sametime, the fireball rises, much like a fierydoughnut. As it rises, there are updraftsthrough the center of the doughnut anddowndrafts on the outside.

3.33 Within seven-tenths of a millise-cond from the detonation, the fireball froma 1-megaton bomb reaches a radius of

FIREBALL

about 220 feet, and this increases to a'maximum of about 3,600 feet in 10 seconds.The diameter is then some 7,200 feet andthe fireball is rising at the rate of 250 to350 feet per second. One minute after deto-nation, the fireball has cooled, due to theemission of heat and entrainment of coolair, to such an extent that it is no longerluminous. It has, by this time, risenroughly 4.5 miles from the point of burst.

PRIMARY SHOCK FRONT \

NUCLEAR a THERMALRADIATION

MILES I 1 1 1

3 4 5 6

FIGURE 3.28a.Chronological development of an air burst: 1.8 seconds after 1-megaton detonation.

NUCLEAR a THERMALRADIATION

.. ""- '".00

REFLECTED SHOCK FRONT

MILES 1

\PR1MARY SHOCK FRONT

COMMENCEMENT OF/ MACH REFLECTEDOVERPRESSURE 16 PSI

I I I 1

2 3 5 6

FIGURE 3.28h. Chronological development of an air burst : 4.6 seconds after 1-megaton detonation.

PRIMARY SHOCK FRONTNUCLEAR a THERMAL

RADIATION

REFLECTED SHOCK FRONT

WIND VELOCITY MACH FRONT180 MPH OVERPRESSURE 6 PSI

MILES I2 3 4 5 6

FIGURE 3.28c.Chronological development of an air burst: 11 seconds after 1-megaton detonation.

33

&If

RATE OF RISEI MT 250 MPH

MUSHROOMSTEM

REFLECTED SHOCK FRONT \PRIMARY SHOCK FRONT \

\NUCLEAR RADIATION

*.NHOT GASEOUSBOMB RESIDUE

AFTERWINDS

MACH FRONT

\\\\\

OVERPRESSURE I

WIND VELOCITY40 MPH

MILES I

TOTAL THERMAL RADIATION CAL SO CM 30 20

1

2 3 4 5 61

7 8 9 10

81

5

FIGURE 3.284.Chronological development. of an air burst: 37 seconds after 1- megaton detonation.

RATE OF RISE130-170 MPH

RADIOACTIVE CLOUD

WIND VELOCITY 275 MPH

MILES I I I r I I I 1I 2 3 4 5 6 7 8 9 10

FIGURE 3.28e.Chronological development of an air burst: 110 seconds after 1-megaton detonation.

THE BLAST WAVE

3.34 At a fraction of a second after theexplosion, a destructive high-pressurewave develops in the air around the fire-ball and moves rapidly away, behavinglike a moving wall of, highly compressedair. After the lapse of 10 seconds, when thefireball of a 1-megaton nuclear bomb has

34

attained its maximum size (7,200 feetacross), the blast front is some 3 milesfurther ahead. About a minute after theexplosion, when the fireball is no longervisible, the blast wave has traveled ap-proximately 12 miles. It is then moving atabout 1,150 feet per second, which isslightly faster than the speed of sound atsea level.

4th

R REFLECTED WAVEI INCIDENT WAVE

1

1.,"

4

R\

TRIPLE POINT-1/

MACH STEM

FIGURE 3.35.Fusion of incident and reflected waves and formation of Mach stem.

THE MACH WAVE

3.35 When the blast wave strikes thesurface of the earth, it is reflected in away similar to a sound wave producing anecho. This reflected blast wave, like theoriginal (or direct) wave, is also capable ofcausing material damage. At a certain re-gion on the surface, the position of whichdepends chiefly on the height of the burstabove the surface and the energy of theexplosion, the direct and reflected blastfronts fuse as shown in Figure 3.35. Thisfusion phenomenon is called the MACHEFFECT. The OVERPRESSURE, i.e., thepressure of the blast wave in excess of thenormal atmospheric value, at the front ofthe Mach wave is generally about twice asgreat as t! at at the direct shock front. Themaximum overpressure value, i.e., at theblast front, is called the Peak overpres-sure.

RREFLECTED WAVEI INCIDENT WAVE

PATH OF TRIPLE POINT

R

R ; \ IMACH!) Rs\

\\V STEM

FIGURE 3.37.Outward motion of the blr.st wave nearthe surface in the Mach region.

3.36 For a "typical" air burst of a 1-megaton nuclear weapon,-the Mach effectwill begin approximately 5 seconds afterthe explosion, in a rough circle at a radiusof 1.3 miles from ground zero. The term"GROUND ZERO" refers to the point onthe earth's surface immediately below (orabove) the point of detonation.

3.37 At first, the height of the Machfront is small (Figure 3.37), but as theblast front centinues to move outward, theheight increases steadily forming a MACHSTEM. During this time, however, the ov-erpressure, like that in the original blastwave, decreases correspondingly becauseof the continuous loss of energy and theever-increasing area of the advancingfront. After the lapse of about 40 seconds,when the Mach front from a 1-megatonnuclear bomb is 10 miles from ground zero,the overpressure will have decreased to

35

roughly 1 poundper square inch. Most ofthe material damage caused, by an airburst nuclear bomb is due mainlydi-rectly or indirectlyto the blast (or shock)wave. The majority of structures will suf-fer some damage from air blast when theoverpressure in the blast wave is aboutone-half pound per square inch or more.

3.38 The distance from ground zero atwhich the Mach stem commences, and towhich an overpressure of one-half poundper square inch will extend, depends onthe yield or size of the explosion and onthe height of the burst. As the height ofthe burst for an explosion of given energyis decreased, Mach reflection commencesnearer to ground zero, and the overpres-sure at the surface near ground zero be-comes larger. If the bomb is exploded at agreater height, the Mach fusion com-mences farther away, and the overpres-sure at the surface is reduced. An actualcontact surface burst leads to the highestpossible overpressures near ground zero,but no Mach effect occurs, since there isno reflected wave.

3.39 In the nuclear explosions over Hi-roshima and Nagasaki during World WarII, the height of burst was about 1,850feet. It was estimated, and has since beenconfirmed by nuclear test explosions, thata 20-kiloton bomb burst at this heightwould cause maximum blast damage tostructures on the ground for the particu-lar targets concerned. Actually, there is nosingle optimum height of burst, with re-gard to blast effects, for any specified ex-plosion energy yield, because the choienheight of burst will be determined by thenature of the target. As a rule, strong (orhard) targets will require low air or sur-face bursts. For weaker targets, which aredestroyed or damaged at relatively lowoverpressures or dynamic pressures (thedynamic pressure is a function of the windvelocity. and air density behind the blastfront), the height of burst may be raised inorder to increase the area of damage, sincethe distance at which low overpressurewould result would be extended because ofthe Mach effect.

36

POSITIVE AND NEGATIVE PHASES

3.40 As the blast wave travels in theair away from its source, the -overpres-sures at the front steadily decrease, andthe pressure behind the front falls off in aregular manner. After a short time, whenthe blast front has traveled a certain dis-tance from the fireball, the pressure be-hind the front drops below that of thenormal atmosphere and a so-called NEGA-TIVE PHASE of the blast wave forms. Inthis region the air pressure is below that ofthe original (or ambient) atmosphere.

3.41 During the negative overpressure(or suction) phase, a partial vacuum isproduced and the air is sucked in, insteadof being pushed away, as it is when theoverpressure is positive. In the positive (orcompression) phase, the wind associatedwith the blast wave blows away from theexplosion, and in the negative phase itsdirection is reversed.

3.42 This wind is often referred to as a"transient" wind because its velocity de-creases rapidly witn time. During the posi-tive phase, these winds may have peakvelocities of several hundred miles perhour at points near ground zero, and evenat more than 6 miles from the explosion ofa 1-megaton nuclear explosion, the peakvelocity may be greater than 70 miles perhour. It is evident that such strong windscan contribute greatly to the blast damagefollowing an air burst. The peak negativevalues of overpressure are small comparedwith the peak positive overpressures.Thus, it is during the compression phasethat most of the destructive action of blastfrom an air burst will be experienced.However, the winds associated with thenegative phase can be quite damaging toweakened structures.

3.43 From the practical viewpoint, it isof interest to visualize the changes of ov-erpressure in the blast wave with time ata fixed location. The variation of overpres-sure with time that would be observed atsuch a location in the few seconds follow-ing the detonation is shown in Figure3.43a. The corresponding general effects tobe expected on a light structure, a tree,and a small animal are indicated at the

PRESSURE PHASE

2

SUCTION PHASE

FIGURE 3.43a.Variation of pressure with time at a fixed location and effect of blast wave passing over astructure.

left of the figure. Additional data is pre-sented in Figures 3.43b and 3.43c.

BLAST CASUALTIES

3.44 There are four different kinds ofinjuries caused by the blast of an atomicweapon. Victims may be injured in one or

43

all of these four ways, depending uponmany factors, including the degree of pro-tection, closeness to ground zero, size ofbomb, height of detonation, etc.

3.45 The four kinds of blast injuriesare:

(1) primary blast injuries, caused bythe high pressures of the blast wave;

37

EW N

Z '6"

O

Ila 5;13121T-L,

iii t.I 2t." t

6'

h' '2k .

2tiEE

....-

1 ,OSZEt.' h

=

:4

- NI .i''

g','- .10

-50-- 44 3.45 -0.036 1.2

-45- 51 3.45 -0.049- 1.4

- -- 8 -

- 40 -, -60 T 3.44 .. 0.07 1.7

-7--35- 72 3A3 - Oil 2.1

- --25-

89 - 340 - 0.16 26 -- -,_ -

117 3.24 0.28 3.5 -

-4--20-- 177 3.02 0.60 5.5 -

-15 -..- 278 2_69 1.40 9.4 -3-- 10- 464 2.25 - 5.22 18.0 -- 2

- 5 - 307 1.75 3.60 27.0 -,- 1

n

LIGHT DAMAGE TO WINDOW FRAMES AND DOORS, MODERATEPLASTER DAMAGE OUT TO ABOUT 15 MILES, GLASS BREAKAGEPOSSIBLE OUT TO 30 MILES.

FINE KINDLING FUELS IGNITED.

SMOKESTACKS SLIGHT DAMAGE.

WOOD-FRAME BUILDINGS MODERATE DAMAGE.

RADIO AND TV TRANSMITTING TOWERS- MODERATE DAMAGE

WOOD-FRAME BUILDINGS SEVERE DAMAGE.

TELEPHONE & POWER LINES LIMIT OF SIGNIFICANT DAMAGE.

WALLBEARING, BRICK BUILDINGS (APARTMENT HOUSE TYPE)MODERATE DAMAGE

WALL-BEARING, BRICK BUILDINGS (APARTMENT HOUSE TYPE)SEVERE DAMAGE.

LIGHT STEEL-FRAME, INDUSTRIAL BUILDINGS MODERATE DAMAGELIGHT STEELFRAME, INDUSTRIAL BUILDINGS SEVERE DAMAGE.

MULTISTORY, WALL- BEARING BUILDINGS (MONUMENTAL TYPE)MODERATE DAMAGE.

MULTISTORY, WALL-BEARING BUILDINGS (MONUMENTAL TYPE)SEVERE DAMAGE.HIGHWAY AND FIR TRUSS BRIDGES MODERATE DAMAGE

MULTISTORY, STEEL-FRAME BUILDING (OFFICE TYPE) SEVEREDAMAGE.TRANSPORTATION VEHICLES MODERATE DAMAGE

MULTISTORY, REINFORCED-CONCRETE FRAME BUILDINGS (OFFICETYPE). SEVERE DAMAGE.mULTISTORY,BLASTRESISTANT DESIGNED, REINFORCED CONCRETEBUILDINGS MODERATE

MULTISTORY, LASTRESISTANT DESIGNED, REINFORCED CONCRETEBUILDINGS SEVERE

ALL OTHER (ABOVE GROUND) STRUCTURES SEVERELY DAMAGED ORDESTROYED

FIGURE 3.43b, Damage ranges for a 1-MT typical air burst.

(2) those from the impact of missilesthrown about by the force of the blast;

(3) result of being thrown about by theblast; and =-

(4) miscellaneous injuries, such as ex-posure to ground shock; dust inhalation;fires caused by the explosion, etc.3.46 Seventy percent of those who sur-

vived the nuclear bombing in Japan suf-fered from blast injury. Since many of thesurvivors were also injured in other ways(burns and/or radiationboth to be dis-cussed later) we cannot say that this is thepercentage of injuries caused by blast.Nevertheless, blast was one of the majorcauses of injury and, certainly, a majorcause of death.

THE BOMB (RADIOACTIVE) CLOUD3.47 In addition to the transient winds

associated with the passage of the blastfront, a strong updraft with inflowingwinds, called "afterwinds", is produced inthe immediate vicinity of the detonationdue to the rising fireball. These afterwinds

38

4 (1

cause varying amounts of dirt and debristo be sucked up from the earth's surfaceinto the atomic cloud. (Refer to Figure3.28e.)

3.48 At first, the rising mass of bombresidue carries the particles upward, butafter a time, the particles begin to spreadout and fall slowly under the influence ofwind and gravity. This is FALLOUT.

THERMAL RADIATION

3.49 Immediately after the fireball isformed, it starts to emit thermal radiation.Because of the very high temperatures ofthe fireball, this radiation consists of visi-ble light rays, invisible ultraviolet rays ofshorter wave length, and invisible in-frared rays of longer wave length. Theserays all travel with the speed of light. Dueto certain physical phenomena associatedwith the absorption of the thermal radia-tion by the air in front of the fireball, thesurface temperature of the fireball under-goes a curious change, The temperature

STRUCTURE TYPE DAMAGE

EXPLOSION YIELD(Distance in miles)

100 KT 1MT 10 MT

WOOD-FRAME BUILDING,RESIDENTIAL TYPE

MODERATE 3.2 6.6 14.

SEVERE 2.4 5.5 12

WALL-BEARING, MASONRYBUILDING, APARTMENTHOUSE TYPE

MODERATE 2.4 4.7 10

SEVERE 1.7

.

3.5 8.7

MULTISTORY, WALL-BEARING BUILDING,MONUMENTAL TYPE

MODERATE 1.6 3.5 7.4

SEVERE 1.3 2.8 6.1

REINFORCED CONCRETE(NOT EARTHQUAKERESISTANT) BUILDING,

CONCRETE WALL, SMALLWINDOW AREA

MODERATE 1.5 3.4 7.2

SEVERE 1.1 2.5 5.9

FOR A SURFACE BURST THE RESPECTIVE DISTANCES ARE THREE QUARTERS OFTHOSE FOR AN AIR BURST OF THE SAME YIELD.

FIGURE 3.43c.Maximum ranges from ground zero for structural damge from air bursts.

decreases rapidly for a fraction of a sec-ond. Then, the surface temperature in-creases again for a somewhat longer time,after which it falls continuously. In otherwords, there are effectively two surface-temperature pulses: the first is of veryshort duration, whereas the second lastsfor a much longer time. This behavior isquite standard with all size weapons, al-though the duration times of the twopulses increase with the energy yield ofthe explosion. After about 3 seconds fromthe detonation of a 20 KT bomb, the fire-ball, although still very hot, has cooled tosuch an extent that the thermal radiationis no longer important, whereas amountsof thermal radiation still continue to beemitted from the fireball at 11 secondsafter a 1-megaton explosion.

3.50 Corresponding to the two tempera-ture pulses, there are two pulses of emis-sion of thermal radiation from tie fireball(Figure 3.50). In the first pulse, whichlasts about a tenth of a second for a 1-megaton explosion, the temperatures aremostly very high. As a result, much of theradiation emitted in this pulse is in theultraviolet region. Moderately large dosesof ultraviolet radiation can produce pain-ful blisters, in milder form these effectsare familiar as sunburn. However, in mostcircumstances, the first pulse of thermalradiation is not a significant hazard, withregard to skin burns, for several reasons.In the first place, only about 1 percent ofthe thermal radiation appears in the ini-tial pulse because of its short duration.Second, the ultraviolet rays are readily

4 5

39

absorbed in the atmospheres so that thedose delivered at a distance from the ex-plosion may be comparatively small. Fur-ther, it appears that the ultraviolet radia-tion from the first pulse could cause signif-icant effect on the human skin only withinranges where people would be kille out-right by the blast and at which otherradiation effects are much more serious.

3.51 The situation with regard to thesecond pulse is, however, quite different.This pulse may last for several secondsand carries about 99 percent of the totalthermal radiation energy from the bomb.Since the temperatures are lower than inthe first pulse, most of the rays reachingthe earth consist of visible and infraredlight. It is this radiation which is the maincause of skin burns of various degreessuffered by exposed individuals out to 12miles or more from the explosion of a 1-megaton bomb, on a fairly clear day. Thewarmth may be felt at a distance of 75iniles. Far air bursts of higher energyyields, the corresponding distances, will, ofcourse, be greater. Generally, thermal ra-diation is capable of causing skin burns onexposed individuals at such distances fromthe nuclear explosion that the effects ofblast and of the initial nuclear radiationare not significant.

THERMAL RADIATION CASUALTIES

3.52 It is convenient to divide thermal

6 $0.0

4

I-

wO 5.0

9.0

4.0

7.0

6.0

z40(7, w 4.0

tt3.0

O 2.0

O .1.0 2.0 50 4.0 5.0 6,0 70 4.0 9.0 10.0 110 I2.0

TIME AFTER EXPLOSION(RELATIVE SCALE)

FIGURE 3.50.Emission of thermal radiation in twopulses.

40

43

burns due to a nuclear explosion into twoclasses, namely (1) primary burns, and (2)secondary burns. As in the case of blastinjuries, the terms primary and secondaryrefer to the manner in which the burnsare inflicted. Those in the first class are adirect result of thermal radiation from thebomb, while those in the second grouparise indirectly from fires caused by theexplosion. From the medical point of view,a burn is a burn, whether received as aflash burn from the initial thermal burstor, at a later time, from the burning envi-ronment.

3.53 Experiments in the laboratOry andin the field have established criteria forassessing the degree of thermal damage tobe expected for doses of thermal radiationdelivered to human tissue within specifiedtime limits. Medical diagnosis usually re-cognizes three grades of thermal injury:first, second and third degree injury inascending order of severity. A first-degreeburn corresponds to a moderate sunburnor erythema. Such damage, while quitepainful, is reparable with time and re-quires no special treatment beyond therelief of pain. The second-degree burn in-volves the skin thickness down to andincluding portions of the dermis. A charac-teristic feature of second-degree burns isthe formation of blisters. The second-de-gree burn is extremely painful but alsoreparable with time. Infection usually oc-curs since the protective barrier of theepidermis has been pierced, leaving thetissues open to infective pathogens. Giventime and opportunity to combat infection,the majority of second-degree wounds healwithout undue aftereffects though per-manent pigmentation changes may persist.The third-degree burn involves completedestruction of the whole skin thickness.Except for very small area burns these arenot reparable with time but require skingrafting in all cases. Infection is invaria-bly present. Paradoxically, the third-de-gree burn is not as painful as the second-degree burn because the nerve endingshave been destroyed; yet third-degreeburns to more than 25 percent of the hu-man body area might represent a fatalinjury.

3.54 The treatment of severe thermalinjury on areas in excess of 25 percent ofthe whole body represents a grave medicalproblem even in a modern hospital andunder the best of circumstances. For massburn casualties under field conditions thesituation takes on overwhelming propor-tions. An unwarned urban populationcaught out of doors during a nuclear at-tack would suffer almost complete annihi-lation from blast and thermal energy outto a radius of many miles from groundzero. While it is feasible to avoid theprompt thermal flash by taking cover, it isnot so evident how to avoid the secondaryeffects of the burning environment whichdevelops soon after the burst. It is proba-ble that burns from secondary fires engen-dered by the bomb would represent a ma-jor proportion of the casualties even for apopulation which had received warning ofimminent attack. (From 65-85% of theatom bomb survivors in Japan wereburned to some degree.) Figure 3.54 showsthe ranges in miles at which people in theopen would suffer various degrees of skinburn from surface burst weapons of differ-ent power.

THERMAL EFFECTS OF WEAPONS OFDIFFERENT YIELDS

3.55 A 10MT weapon radiates 500 timesas much heat as a 20KT bomb. Accordingto the "inverse square" law a 10MTweapon should produce the same amountof heat as the 20KT weapon at .a distance

RADII IN MILES

WEAPON POWER MKT 100 KT I MT 2 MT 5 MT IOMT

FIRST DEGREE BURN 15 30 B0 112 150 21 0

S E C O N D DEGREE B U R N 10 2 0 5.5 7 5 1 1 0 15 0

THIRD DEGREE BURN 0.975 1.5 4.75 i25 9.5 13.0

FIGURE 3.54.Range of effects from surface burstson people exposed in open.

22 times greater (since V500 = 22 approx.).But the heat from the larger bomb isspread over a much longer period, 20 sec-onds compared with a 11/2 second flashfrom the 20KT bomb, so that more of theheat is dissipated.

3.56 Nuclear weapons of 10-100KT de-liver at least 60 percent of the total ther-mal radiation from the second radiationpulse in less than 0.5 second. Weapons inthe 1-10MT range, while producing morethermal energy over a greater radius fromthe burst than weapons of 100KT or less,deliver this thermal energy at a muchslower rate than the small weapons. Thus,for equal thermal doses incident on tissue,the small weapons are more effective inproducing thermal injury because thelarge weapons require anywhere from 5 to15 seconds to deliver 60 percent of thethermal dose. For example, it requires 7-9cal./cm.2 to produce second-degree burnsfrom a 10MT weapon. This illustrates amost important factor: The larger theweapon, the greater the time available forevasive action. However, evasive tacticsmust be exercised before 60 percent of thetotal energy has been delivered. For per-sonnel well indoctrinated in evasive tac-tics, this could mean the difference be-tween a moderate sunburn and severethermal injury. Figure 3.56 shows thermalenergies required to cause first, secondand third-degree burns from differentyield weapons.

3.57 Temporary or permanent blind-ness could be caused by the thermal radia-

4

EXPLOSIVE YIELD I KT 20 KT *OKI I MT 10MT

....

20 VT

FIRST DEGREE BURN 2.0 2.5 2.7 3.2 3.7 3.1

SECCNO DEGREE BURN 4 I 49 54 62 7.2 7.5

TIFK) DEGREE BURN 6.0 7.3 S. 94 10.1 11.4

FIGURE 3.56.Approximate thermal energies in Cal./cm.2 required to cause skin burns in air or surfaceburst.

41

tion if a person is looking in the generaldirection of the fireball at the precise mo-ment of detonation. The lens of the eyefocuses heat as well as light rays on theretina of the eye. Thus in addition to tem-porary or "flash" blindness of a few sec-onds or minutes duration from the intenselight, actual burns of the retina could oc-cur from undue amounts of thermal radia-tion entering the eye. Neither flash blind-ness nor retinal damage constitute majorhazards during daylight because of natu-ral restriction of the diameter of the pupilwhich limits the amount of light enteringthe eye; furthermore the blink reflex, onehundred and fifty thousandths of a second,protects the eye from undue amounts ofradiatioE, except in those cases where thethermaf pulse is delivered within ex-tremely short times. This is the case forlow-yield weapons and can also be true forhigh altitude bursts.

3.58 It is an interesting fact thatamong the survivors in Hiroshima andNagasaki, eye injuries directly attribut-able to thermal radiation appeared to berelatively unimportant. There were manycases of temporary blindness, occasionallylasting up to 2 or 3 hours, but more severeeye injuries were not common.

3.59 The eye injury known as keratitis(an inflammation of the cornea) occurredin some instances. The symptoms, includ-ing pain caused by light, foreign-body sen-sation, lachrymation, and redness, lasted

.for periods ranging from a few hours toseveral days.

EFFECT OF SMOKE, FOG AND SHIELDING

3.6C In the event of an air burst occur-ring above a layer of dense cloud, smoke,or fog, an appreciable portion of the ther-mal radiation will be scattered upwardfrom the top of the layer. This scatteredradiation may be regarded as lost, as faras a point on the ground is concerned. Inaddition, most of the radiation which pene-trates the layer will be scattered and verylittle will reach the given point by directtransmission. These two effects (smoke orfog) will result in a substantial decrease in

42

4E

the amount of thermal energy reaching aground target.

3.61 It is important to understand thatthe decrease in thermal radiation by fogand smoke will be realized only if theburst point is above or, to a lesser extent,within the fog (or similar) layer. If theexplosion should occur in moderately clearair beneath a layer of cloud, or fog, some ofthe radiation which would normally pro-ceed outward into space will be scatteredback to earth. As a result, the thermalenergy received will actually be greaterthan for the same atmospheric transmis-sion condition without a cloud or fog cover.

3.62 Unless scattered, thermal radia-tion from a nuclear explosion, like ordi-nary light in general, travels in straightlines from its source, the fireball. Anysolid object, opaque material, such as awall, a hill, or a tree, between a given objectand the fireball, will act as a shield andprovide protection from thermal radiation.Transparent materials, on the other hand,such as glass or plastics, allow therm alradiation to pass through, only slightlyabsorbed.

3.63 In the case of an explosion in thekiloton range, it would be necessary totake evasive action within a small fractionof a second if an appreciable decrease inthermal injury is to be realized. The timeappears to be too short for such action tobe possible. On the other hand, for explo-sions in the megaton range, evasive actiontaken within a second or two of the ap-pearance of the ball of fire could reducethe severity of injury due to thermal ra-diation in many cases and may even pre-vent injury in others.

NUCLEAR RADIATION

3.64 It was stated in paragraph 3.4 thatone of the unique features of a nuclearexplosion is that it is accompanied by theemission of various nuclear radiations.These radiations, which are quite differentfrom thermal radiation, consist of gamma

.rays, neutrons., beta particles, and a smallproportion of alpha particles. Essentiallyall the neutrons and part of the gammarays are emitted in the actual fission proc-

ess. That is, these radiations are producedsimultaneously with the nuclear explo-sion, whereas the beta particles and theremainder of the gamma rays are liber-ated from fission products in the course oftheir radioactive decay. The alpha parti-cles result from the normal radioactivedecay of the uranium or plutonium thathas escaped fission in the bomb.

3.65 Because of the nature of the phe-nomena associated with a nuclear explo-sion, either in the air or near the surface,it is convenient for practical purposes toconsider the nuclear radiation as beingdivided into two categories; namely, initialand residual.

INITIAL NUCLEAR RADIATION

3.66 The initial nuclear radiation isgenerally defined as that emitted from thefireball and the atomic cloud within thefirst minute after the detonation. It in-cludes neutrons and gamma rays given offalmost instantaneously, as well as thegamma rays emitted by the radioactivefission products in the rising cloud. Itshould be noted that, although alpha andbeta particles are present in the initialradiation, they have not been considered.This is because they are so,easily absorbedthat they will not reach more than a fewyards, at most, from the atomic cloud.

3.67 The somewhat arbitrary time pe-riod of 1 minute for the duration of theinitial nuclear radiation was originallybased upon the following considerations.As a consequence of absorption by the air,the effective range of the fission gammarays and those from the fission productsfrom a 20-kiloton explosion is very roughly2 miles. In other words, gamma rays origi-nating from such a source at an altitude ofover 2 miles can be ignored as far as theireffect at the earth's surface is concerned.Thus; when the atomic cloud has reacheda height of 2 miles, the effects of the initialnuclear radiation are no longer signifi-cant. Since it takes roughly a minute forthe cloud to rise this distance, the initialnuclear radiation is defined as that emittedin the first minute after the explosion.

3.68 The foregoing discussion is based

4 9

on the characteristics of a 20-kiloton nu-clear bomb. For a bomb of higher energy,the maximum distance over which thegamma rays are effective will be greaterthan given above. However, at the sametime, there is an increase in the rate. atwhich the cloud rises. Similarly for a bombof lower energy, the effective' distance isless, but so is the rate of ascent of thecloud. The period over which the initialnuclear radiation extends may conse-quently be taken to be approximately thesame; namely, 1 minute irrespective of theenergy release of the bomb.

3.69 Neutrons produced directly in thethermonuclear reactions mentioned inparagraph 3.18 are of special significance.Some of the neutrons will escape but oth-ers will be captured by the various nucleipresent in the exploding bomb. These neu-trons absorbed by fissionable species maylead to the liberation of more neutrons aswell as to the emission of gamma rays,just as described above for an ordinaryfission bomb. In addition, the capture ofneutrons in non-fission reactions is us-ually accompanied by gamma rays. It isseen, therefore, that the initial radiationfrom a bomb in which both fission andfusion (thermonuclear) processes occur,consists essentially of neutrons andgamma rays. The relative proportions ofthese two radiations may be somewhatdifferent than for a bomb in which all theenergy released is due to fission, but forpresent purposes, this difference may bedisregarded. The range of lethal effectsfroin initial nuclear radiation are wellwithin the areas of severe blast and ther-mal damage.

RESIDUAL NUCLEAR RADIATION

3.70 The radiation which is emitted 1minute after a nuclear explosion is definedas residual nuclear radiation. This radia-tion arises mainly from the bomb residue;that is, from the fission products and, to alesser extent, from the uranium and plu-tonium which have escaped fission. In ad-dition, the residue will usually containsome radioactive isotopes formed as a re-sult of neutron capture by bomb materials.

43

Another source of residual nuclear radia-tion is the activity induced by neutronscaptured in various elements present inthe earth, in the sea, or in the substanceswhich may be in the explosion environ-ment.

3.71 With surface and, especially, sub-surface explosions, the demarcation be-tween initial and residual nuclear radia-tion is not as definite. Some of the radia-tion from the bomb residue will be withinthe range of the earth's surface at alltimes so that the initial and residual cate-gories merge continuously into one another. For very deep underground and un-derwater bursts, the initial gamma raysand neutrons produced in the fission proc-ess may be ignored. Essentially the onlynuclear radiation of importance is thatarising from the bomb residue. It can con-sequently be treated as consisting exclu-sively of the residual radiation. In an airand surface burst, however, both initialand residual nuclear radiation must betaken into consideration.

3.72 One additional important consider-ation of nuclear radiation is that the resid-ual nuclear radiation can, under some con-ditions, represent a serious hazard at greatdistahces from a nuclear explosion, wellbeyond the range of blast, shock, thermalradiation, and initial nuclear radiation.This phenomenonFALLOUTwill be dis-cussed at length in later chapters. ,

CHARACTERISTICS OF A SURFACE BURST

3.73 In a surface burst, the ball of firein its rapid initial growth will touch thesurface of the earth. Because of the in-tense heat, a considerable amount of rock,soil, and other material located in the areawill be vaporized and taken into the ball offire. It has been estimated that if only 5percent of a 1,- megaton bomb's energy isspent in this manner, something like 20,-000 tons .of,yaporized soil material will beadded to the" normal constituents of thefireball. In addition, the high winds at theearth's surface will cause large amounts ofdirt, dust, and other particles to be suckedup as the ball of fire rises (See Figure3.28e).

44

3.74 An important difference between asurface burst and an air burst is that in thesurface burst the atomic cloud is muchmore heavily loaded with debris (and soproduces much more FALLOUT). This willconsist of particles ranging in size fromthe very small ones produced by condensa-tion as the fireball cools, to the muchlarger particles which have been raised bythe surface winds. The exact compositionof-the crourr Will, `Of course, depend on thenature of the terrain and the extent ofcontact with the fireball.

3.75 For a surface burst associatedwith a moderate amount of debris, as wasthe case in several test explosions inwhich the bombs were detonated near theground, the rate of rise of the cloud ismuch the same as given earlier for an airburst. The atomic cloud reaches a heightof several miles before spreading out intoa mushroom shape.

3.76 The vaporization of dirt and othermaterial when the fireball has touched theearth's surface, and the removal of mate-rial by the blast wave and winds accompa-nying the explosion, result in the forma-tion of a crater. The size of the crater willvary with the height above the surfce atwhich the bomb is exploded and with thecharacter of the soil, as well as the energyof the bomb. It is believed that for a 1-megaton bomb there would be no apprecia-ble crater formation unless detonation oc-curs at an altitude of 450 feet or less.

3.77 If a nuclear bomb is exploded nearthe surface of the water, large amounts ofwater will be vaporized and carried upinto the atomic cloud. For example, if it issupposed, as above (paragraph 3.73), that 5percent of the energy of the 1-megatonbomb is expended in this manner, about100,000 tons of water will be convertedinto vapor. At high altitudes this will con-dense to' form water droplets similar tothose in an ordinary atmospheric cloud.

5 0

AIR BLAST AND GROUND SHOCK

3.78 The overall blast effect due to theair shock from a surface burst will be lessthan that from an air burst for weapons ofequivalent yield. For one thing, part of the

energy of the bomb is used up in vapor-izing materials on the surface and informing a crater. In addition, up to 15percent of the energy may go into groundshock. The main point, however, is thatbecause the bomb explodes close to theearth's surface, the Overpressure nearground zero will be much greater than foran air burst, but it will fall off more rap-idly with increasing distance from groundzero.

3.79 As a result, energy will be wastedon targets close to ground zero whichcould have been destroyed by much loweroverpressures. At the same'time, the over-pressures at some distance away will betoo 'Tow to cause any considerable damage.In other words, there will be an "over-destruction" of nearby surface targets andan "under-destruction" of those furtheraway. The energy that has gone to produceground shock may contribute, however, tothe destruction of underground targets pro-tected from the air blast such as missilelaunching sites. Figure 3.43c, (and its leg-end), will provide additional specific infor-mation on surface bursts.

THERMAL RADIATION

3.80 The general characteristics of thethermal radiation from a nuclear detona-tion at the surface will be essentially thesame as for an air burst, described previ-ously. As stated earlier, if evasive actioncan be taken within a second or so, part ofthe heat radiation may be avoided.

INITIAL NUCLEAR RADIATION

3.81 The initial nuclear radiation from

THROWOUT

a surface burst will be similar to that in anair burst. However, if the low level nuclearexplosion occurred in a more or less built-up area, the structures through which itpassed would serve to reduce, even thoughthey would not completely shield, thegamma radiation. For practical purposes,however, it would be advisable to treatthese two types of burst as the same as faras initial nuclear radiation is concerned.

RESIDUAL NUCLEAR RADIATION

3.82 With respect to residual radioac-tivity, a nuclear explosion at a low level'would produce effects somewhat similar toa subsurface burst. That is, a considerableamount of dirt and other debris or water,would be hurled into the air, and upondescending, it might produce a base surge(highly radioactive cloud of dust or vapor)which will be contaminated partly fromthe condensation on the ground of thenuclear reaction products from the ball offire, partly from the fallout of heavierpieces, and partly from radioactivity in-duced by neutrons.

CHARACTERISTICS OF A SUBSURFACEBURST

3.83 When a nuclear bomb is explodedunder the ground, a ball of fire is formedconsisting of extremely hot gases at highpressures, including vaporized earth andbomb residue. If the detonation occurs atnot too great a depth, the fireball may beseen as it breaks through the surface,before it is obscured by clouds of dirt, anddust. As the gases are released, they carryup with them into the air large quantities

AIR SHOCK FRONT

DIRT COLUMN

MILES0 0.5 1.0 1.5 2.0

FIGURE 3.83a.Chronological development of a 100KT shallow underground burst: 2.0 seconds after detona-tion.

45

NUCLEAR RADIATION

THROWOUT

MILES I0 0.5 1.0 I.5 2.0

Lamm 3.83b.Chronological development of a 100KT shallow underground burst: 9.0 seconds after detonation.

CLOUD

NUCLEAR RADIATION

s"..s: BASE SURGE FORMING

THROWOUT

MILES I 1

0.5 1.0 1.51

2.0

FIGURE 3.83c.--7Chronological development of a 100KT shallow underground burst 45 seconds after detonation.

BASE'SURGE

CLOUD

NUCLEAR RADIATION

COLUMN

MILES I1

0.5 1.0 I. 2.0

FIGURE 3.83d.Chronological development of a 100KT shallow underground burst: 4.5 minutes after detonation.

46

of earth, rock, and debris in the form of acylindrical column. The chronological devel-opment of some of the phenomena associ-ated with an underground explosion, hav-ing an energy yield of 100 kilotons, isrepresented by Figures 3.83a to 3.83d.

3.84 It is estimated from tests made inNeyada that, if a 1-megaton bomb weredrotiPed from the air and penetrated un-derground in sandy soil to a depth of 50feet before exploding, the resulting craterwould be about 300 feet deep and nearly1,400 feet across. This means that approxi-mately 10 million tons of soil and rockwould be hurled upward from the earth'ssurface. The volume of the crater and themass of material thrown up by the force ofthe explosion will increase roughly in pro-portion to the energy of the bomb. As they'descend to earth, the finer particles of soilmay initiate a base surge as shown inFigure 3.83d.

AIR BLAST AND GROUND SHOCK

3.85 The rapid expansion of the bubbleof hot, high-pressure gases formed in theunderground burst initiates a shock wavein the earth. Its effects are somewhatsimilar to those of an earthquake of mod-erate intensity, except that the disturb-ance originates fairly near the surface in-stead of at a great depth. The difference indepth of origin means that the pressuresin the underground shock wave caused bya nuclear bomb probably fall off more rap-idly with distance than do those due toearthquake waves.

3.86 Part of the energy from an under-ground nuclear explosion appears as ablast wave in the air. The fraction of theenergy imparted to the air in the form ofblast depends primarily upon the depth ofthe burst. The greater the penetration ofthe bomb before detonation occurs, thesmaller is the proportion of the shock en-ergy that escapes into the air.

THERMAL AND NUCLEAR RADIATION

3.87 Essentially all the thermal radia-tion emitted by the ball of fire while it isstill submerged is absorbed by the sur-rounding earth. When the hot gases reach

the surface and expand, the cooling is sorapid that the temperature drops almostimmediately to a point where there is nofurther appreciable emission of thermalradiation. It follows, therefore, that in anunderground nuclear explosion the ther-mal radiation can be ignored as far as itseffects on personnel and as a source of fireare concerned.

3.88 It is probable, to, that most of theneutrons and gamma rays liberatedwithin a short time of the initiation of theexplosion will also be absorbed by theearth. But, when the fireball reaches thesurface and the gases are expelled, thegamma rays (and beta particles) from thefission products will represent a form ofinitial nuclear radiation. In addition, theradiation from the fission (and neutron-induced radioactive) products present inthe cloud stem, radioactive cloud, and basesurge, all three of which are formed withina few seconds of the burst, will contributeto the initial effects.

3.89 However, the fallout from thecloud and the base surge are also responsi-ble for the residual nuclear radiation. Fora subsurface burst, it is thus less meaning-ful to make a sharp distinction betweeninitial and residual radiation, such as isdone in the case of an air burst. The initialnuclear *radiation merges continuouslyinto those which are produced over a pe-riod of time following the nuclear explo-sion.

HIGH ALTITUDE BURSTS

3.90 For nuclear detonations at heightsup to about 100,000 feet the density of airis such that the distribution of the explo-sion energy remains almost unchanged,approximating that described for an airburst, e.g., about 45 to 55 percent (of thefission energy) appears as blast and shockand 30 to 40 percent is received as thermalradiation.

3.91 At greater altitudes, this distribu-tion begins to change noticeably with in-creasing height of burst, a smaller propor-tion of the energy appearing as blast. It isfor this reason that the level of 100,000feet has been chosen for distinguishing

47

53

between air bursts and high-altitudebursts.

3.92 There is, of course, no sharpchange in behavior at this elevation, andso the definition'of a high-altitude burst asbeing at a height above 100,000 feet issomewhat arbitrary. Although there is aprogressive decline in the blast energywith increasing height of burst above 100,-000 feet, the proportion of the explosionenergy received as effective thermal ra-diation on the ground does not at firstchange appreciably. This is due to theinteraction of the primary thermal radia.:tion with the surrounding air and its sub-sequent emission in a different spectralregion. At still higher altitudes, the effec-tive thermal radiation received on theground decreases and is, in fact, less thanat an equal distance from an air burst ofthe same total yield.

3.93 One aspect of a high-altitude burstthat has received increased attention inrecent years is the electromagnetic pulse(EMP). Its implications were first notedduring an experimental high-altitudeburst over Johnson Island in the PacificOcean in 1962 when street light failuresand communications disruptions occurredon Oahu, 750 miles away. In an era ofintercontinental ballistic missile systems,and defenses against those missiles, thepossibility of a high-altitude burst in anuclear attack becomes very real.

3.94 Put simply, the electromagneticpulse is that portion of the electromag-netic spectrum (Figure 2.42) in the me-dium to low frequency range extendingroughly from the frequencies used in ra-dar and TV down to those used in electricpower. Since most of the energy is ra-diated in the frequency bands commonlyused for radio and TV communications, itis sometimes called "radio-flash." It is dif-ferentiated from the thermal radiation"guise" that produce heat and light andthe initial radiation "pulse" of gamma andX-rays.

3.95 There is concern about EMP be-cause the energy in the pulse can be col-lected and concentrated, much as thesun's rays can be focused to produce a fire,

t)

I

as shown in the upper portion of Figure3.95. The lower portion of the diagramshows some common EMP energy collec-tors. Sufficient energy can be collected bythese means to cause damage to attachedelectrical and electronic equipment.

3.96 In a surface or near-surface burstthe relevant EMP energies are generallywell within the blast and thermal damageareas close to the point of nuclear detona-tion and thus cover a relatively small geo-graphical area.

3.97 By contrast, if a nuclear weapon isdetonated high above the earth's atmos-phere, the X-rays and gamma rays emit-ted downward from the explosion will beabsorbed in a big "pancake" layer of theatmosphere between 121/2 and 25 milesabove the earth's surface, as shown inFigure 3.97. The gamma energy is con-verted into lower-frequency electromag-netic energy in this interaction region andpropagated downward to the earth's sur-face as a very brief but powerful electrom-agnetic pulse. The strength of this pulseon the ground is much the same as in themoderate damage area of a surface burst.However, very large areas, otherwise un-damaged, can be affected by the high alti-tude detonation, as the lateral extent ofthe "interaction region" is generally lim-ited only by the curvature of the earth.

3.98 The extpnt of that damage can beseen by considering a typical high-altitudeburst over Omaha, Nebraska as shown inFigure 3.98. Within the circle passingthrough Dallas, Texas the EMP hazardwould be the greatest. The outer circleshows that there is potential damage fromEMP effects over the whole area of theUnited States.

3.99 EMP can cause two kinds of dam-age. First, functional damage that wouldrequire replacement of a component orpiece of equipment. Examples would bethe burnout of a radio receiver "front end"or the blowing of a fuse. Second, opera-tional upset of equipment such as openingof circuit breakers or erasure of a portionof the memory of a computer.

3.100 Experiments have shown that CDradiation detection equipment is not sus-

49

:...4.g.fgt.',., ' / ,,.......":"4 , `.... :.... ,:...'..

*, , ..,

*..;rt."`",..?"--:,0.; ...... ....,..... ,

,'''',:-\ O 4,ks ':1 . ' h

...ts .44.'T. : + e HIGH ALTITUDE DETONATION ,...4.,

44.5siX ...............seewee -...er x s- ee-e- szwwe 51.15,477:77....N.44.4 1....

ni.. V' , s s:4.i* s; Z '', ,` .\5 k ;'1,,,:">,,,,I

' ' :. .D., , .., \ s' o.,::*.,....,

.. 4 .r, :,...,4,,,,,.., .7, ,, ,. , - ... ..:,. .4.....4, - . > -.....t. , .......

..,......S,,

gINTERACTIONREGION

I

EM FIELDS

EARTH

EM energy is picked up by long conductorand delivered to sensitive equipment.

EMP ENERGY FROM HIGH ALTITUDE BURST.

50

From: Survive, November-December 1969

FIGURE 3.97.EMP energy from high altitude burst.

5G

EMP GROUND COVERAGE OF HIGH ALTITUDE BURSTS

Source: Defense Nuclear Agency

FIGURE 3.98.EMP ground coverage of high altitude bursts

rt)51

ceptible to direct damage nor are hand.held Citizens Band walkie-talkies or FMradio receivers. The vulnerability of indi-vidual electrical or electronic equipmentcan vary greatly. Transistors and micro-wave diodes, for example, are relativelymore vulnerable than vacuum tubes orelectric motors.

3.101 The EMP threat and protectivemeasures for civil preparedness relatedsystems and equipment are available intechnical publications of DCPA. Emer-gency operating centers, broadcast radioand TV, telephone and electric power sys-tems and public safety radio are some ofthe areas of concern.

3.102 Listed below are seven anti-EMPactions that could be applicable to localcivil preparedness operations.

1. Maintain a supply of spare parts.2. Shift to emergency power at the earli-

est possible time.3. Rely on telephone contact during

threat period so long as it remainsoperational.

4. If radio communication is essentialduring threat period, use only onesystem at a time. Disconnect all othersystems from antennas, cables, andpower.

5. Disconnect radio base stations whennot in use from antennas and powerline.

6. Plan for mobile-to-mobile backup com-munications.

7. Design emergency operating plans sothat operations will "degrade grace-fully" if communications are lost.

SUMMARY OF EFFECTS OF VARIOUS TYPEBURSTS 4

3.103 Some general conclusions can beoffered in summary of the degree or sever-ity of the particular effects of the varioustypes of nuclear detonations. The variousdegrees are relative to each other for agiven burst type, and an. best interpretedin terms of the descriptions given below.

' This summary is reprinted from THE EFFECTS OF NUCLEARWEAPONS.

52

HIGH ALTITUDE BURST 5

LIGHT: Very intense.HEAT: Moderate, decreases with increas-

ing burst altitude.INITIAL NUCLEAR RADIATION: Negligible.

SHOCK: Negligible.

AIR BLAST: Small on the ground, decreas-ing with increasing burst altitude.

EARLY FALLOUT: None.

SUMMARY: The most significant effect willbe flash blindness over a very largearea; eye burns will occur in personslooking directly at the explosion. Othereffects will be relatively unimportant.

AIR BURST

LIGHT: Fairly intense, but much less thanfor high-altitude burst.

HEAT: Intense out to considerable die,tances.

INITIAL NUCLEAR RADIATION: Intense, butgenerally hazardous out to shorter dis-tance than heat.

SHOCK: Negligible except for very low airbursts.

AIR BLAST: Considerable out to distancessimilar to heat effects.

EARLY FALLOUT: Negligible.

SUMMARY: Blast will cause considerablestructural damage; burns to exposedskin are possible over a large area andeye effects over a still larger area; ini-tial nuclear radiation will be a hazard atcloser distances; but the early fallouthazard will ,be negligible.

GROUND SURFACE BURST

LIGHT: Less than for an air burst, but stillappreciable.

HEAT: Less than for an air burst, butsignificant.

INITIAL NUCLEAR RADIATION: Less thanfor an air burst.

SHOCK: Will cause damage within aboutthree crater radii, but little beyond.

As modified by 3.93-3.102.

AIR BLAST: Greater than for an air burstat close-in distances, but considerablyless at farther distances.

EARLY FALLOUT: May be considerable (fora high-yield weapon) and extend over alarge area.

SUMMARY: Except in the region clos-e'toground zero, where destruction wouldbe virtually complete, the effects ofblast, thermal radiation, and initial nu-clear radiation will be less extensivethan for an air burst; however, earlyfallout may be a very serious hazard"over a large area which is unaffected byblast, etc.

SHALLOW UNDERWATER BURST

LIGHT, HEAT, AND INITIAL NUCLEAR RA-DIATION: Less than for a ground surfaceburst, depending on the extent to whichthe fireball breaks through the surface.

SHOCK: Water shock will extend fartherthan a water surface burst.

AIR BLAST: Less than for surface burst,depending upon depth of burst.

EARLY FALLOUT: May be considerable, ifthe depth of burst is not too large, andin addition there may be a highly radio-active base surge.

SUMMARY: Light, heat, and initial nuclearradiation will be less than for a groundsurface burst; early fallout can be sig-nificant, and at distances not too farfrom the explosion the base surge willbe an important hazard.

WATER SURFACE BURST

LIGHT: Somewhat more intense than for aground surface burst.

HEAT: Similar to ground surface burst.INITIAL NUCLEAR RADIATION: Similar to

ground surface burst.SHOCK: Water shock can cause damage to

ships and underwater structures to aconsiderable distance.

AIR BLAST: Similar to ground surfaceburst.

EARLY FALLOUT: May be considerable.

SUMMARY: The general effects of a water

surface burst are similar to those for aground surface burst, except that theeffect of the shock wave in water willextend farther than ground shock. Inaddition, water waves can cause damageon a nearby shore by the force of thewaves and by inundation.

SHALLOW UNDERGROUND BURST

LIGHT, HEAT, AND INITIAL NUCLEAR RA-DIATION: Less than for a water surfaceburst, depending upon how much of thefireball breaks through the surface.

SHOCK: Ground shock will cause damagewithin about three crater radii, but lit-tle beyond.

AIR BLAST: Less than for a surface burst,depending on the'depth of burst.

EARLY FALLOUT: May be considerable, ifthe depth of burst is not too large, andin addition there may be a highly radio-active base surge.

SUMMARY: Light, heat, initial nuclear ra-diation, and blast effects will be lessthan for a surface burst; early falloutcan be significant, but at distances nottoo far from the explosion the radioac-tive base surge will be an importanthazard. Water waves can also causedamage, as in the case of a water sur-face burst.

CONFINED SUBSURFACE BURST

LIGHT, HEAT, AND INITIAL NUCLEAR RA-DIATION: Negligible or none.

SHOCK: Severe, especially at fairly closedistances from the burst point.

,AIR BLAST: Negligible or none.

SUMMARY: If the burst does not penetratethe surface, either of the ground orwater, the only hazard will be fromground or water shock. No other effectswill be significant.

REFERENCES

The Effects of Nuclear Weapons.Glas-stone, Samuel, 1964.

EMP Threat and Protective Measures,DOD/OCD, TR-61, August 1970.

DCPA Attack Environment Manual.

5 3/Pi

NUCLEAR RADIATION MEASUREMENT

Since we cannot hear, see, smell, taste orfeel nuclear radiation from the fallout, wemust rely entirely upon instruments inorder to DETECT its presence and MEAS-URE the degree of danger. In this chap-ter, then, we will look at:

HOW nuclear radiation may be de-tected

HOW nuclear radiation may bemeasured

WHAT instruments exist to do the de-tecting and the measuring

HOW do instruments operateWHY do we need different types of

instrumentsWHAT are the units we use to meas-

ure nuclear radiation

INTRODUCTION

4.1 Man is aware of his environmentthrough his senses. He can see, smell,taste, hear and feel. Yet, none of thesesenses will make him aware of the pres-ence of nuclear radiation. This situation isnot really unusual. In fact it is like hisinability to respond directly to the wavesof ultraviolet light and radar, television,or radio transmission. For example, a manmay receive a serious sunburn due to ov-erexposure to the sun's ultraviolet rays,yet his first indication of over-exposuremay come several hours later when hefeels pain. In this situation he was notaware of the ultraviolet rays during theexposure period; however, in a sense, hedid detect the ultraviolet light indirectlysince he certainly would be aware of apainful sunburn. Similarly, since man can-not rely on his senses to detect nuclearradiation he must rely on some secondarymeans such as instrumentation.

60

CHAPTER 4

4.2 At the present time, nuclear radia-tion detection instruments are widely usedin industry and research. X-ray films andGeiger counters are items of everydayconversation. In this chapter we will dis-cuss the principles and theory of operationof many nuclear radiation detection in-struments, or radiological instruments aswe will refer to them. These instrumentsare very similar to other types of elec-tronic equipment. Their main distinguish-ing characteristic is their ability to re-spond to nuclear radiation.

4.3 The term DETECTION is used inthis text to include only the indication ofthe presence of nuclear radiation. Theterm MEASUREMENT will be reservedfor both the detection and quantitative,estimation of the amount of nuclear radia-tion present.

PRINCIPLES OF RADIATION DETECTION

4.4 Radiologicai instruments detect theinteraction of radiation with some type ofmatter. The different principles of radia-tion detection are characterized by thenature of the interaction of the radiationwith the detecting or sensing element.Several types operate by virtue of theionization which is produced in them bythe passage of charged particles. In otherdetectors, excitation and sometimes molec-ular disassociation play important roles.

4.5 During the 1890's, Henri Becquerelfound that photographic plates, whenplaced in proximity to ores or compoundsof uranium, were affected in the samemanner as if they had been exposed tolight. This occurred even when the plateswere protected by sufficient covering toassure that the strongest light could notaffect them. This date marked the discov-

55

ery of radioactivity, and today this princi-ple is still used to detect and measure theproduct of radioactkvity, NUCLEAR RA-DIATION.

4.6 The photographic detection tech-nique is relatively simple. As a chargedparticle passes through a photographicemulsion, it will generally cause changeswhich will result in a blackening of theemulsion when the film is developed. Thephotographic emulsion consists of finelydivided crystals of a silver halide, usuallysilver bromide, suspended in gelatin andspread evenly on a glass, cellulose, or pa-per base. When charged particles strikethe emulsion, some sort of ionization notwell understood takes place. This local dis-turbance of the electrons in the crystals ofsilver bromide creates a latent imagewhich is invisible to the eye when formed,but which can be developed later by chem-ical action. The chemical developer acts asa reducing agent to deposit metallic silveronly at those points in the emulsion whereradiation interacted and in proportion tothe amount of radiation which acted onthe silver salt. The amount of blackeningon the film is a function of several factors:the time of exposure, the intensity of theexposure, the sensitivity of the film, andthe chemical processes of development. Byrigidly controlling these factors, the black-ening of the film can be made proportionalto the radiation exposure.

4.7 A second method of detecting.radia-tion was again first employed by Beczquerel and Rutherford in their early workwith radioactive substances. Certain ma-terials will produce small flashes of visiblelight when struck by alpha, beta, orgamma radiation. These flashes are calledscintillations. The mechanism of formationof these scintillations is very complex butessentially it involves the initial formationof higher energy (or excited) electronicstates of molecules (or atoms) in certainmaterials. Some of the absorbed energywhich has been derived directly or indi-rectly from £he incident radiation will beemitted in a very short time as photons ofvisible or ultraviolet light. These lightphotons are then converted into an electri-cal current by a photomultiplier tube and56

the current is measured. Since the lightintensity and the resulting electrical cur-rent are proportional to the rate of radia-tion exposure, the instrument can be cali-brated to read radiation exposure rates.

4.8 A third principle for detecting ra-diation is based on the fact that manysubstances undergo chemical changeswhen exposed to radiation. This is particu-larly true of chemicals in aqueous solu-tions where the decomposition of thewater itself contributes to the reaction. Ifthe extent of the chemical change can beconveniently measured, the reaction canbe used for measuring radiation. Thereare several chemical reactions which maybe utilized in this manner. One of the firstused was the liberation of acid from achlorinked hydrocarbon such as chloro-form. Chloroform, water, and an indicatordye are sealed into a glass tube. As radia-tion penetrates the tube, hydrochloric acidis liberated from the chloroform. The liber-ation of this acid reduces the pH of thesolution and causes a distinctive colorchange in the .dissolved indicator. The ex-tent of the color change is an estimate ofthe radiation exposure of the tube.

4.9 Becquerel's discovery that gasesbecome electrical conductors as a result ofexposure to radiation provides us with afourth means of detecting and measuringradiation. When a high-speed particle or aphoton gasses through a gas, it may causethe removal of an electron from a As -rcztralatom or molecule causing the formation ofan ion pair. This process of ionization in agas is the basic phenomenon in all EN-CLOSED GAS VOLUME INSTRUMENTS. The elec-tron produced may have rather high ener-gies and may produce more ionization inthe gas until its energy is expended and itis finally captured by an oppositelycharged ion. If two oppositely charged col-lecting electrodes are introduced into thegas filled chamber, the ion pairs will mi-grate to their respective electrodes. Nega-tive ions mill move toward the positivelycharged electrode and the positive ionstoward the negatively charged one. Whenthe ions reach the electrodes, they will beneutralized, resulting in a reduction thecharge on the electrodes. In one type of

instrument this loss in charge is used as ameasure of the radiation exposure. In an-other type, batteries are used to replacethe charge on the electrodes resulting in acurrent flow in the external circuit. Withincertain limits, this ionization current willbe proportional to the radiation exposurerate.

4.10 In addition to the four principlesdiscussed above, there are several otherprinciples which may be utilized for thedetection of radiation, but to date thesehave not been as widely used.

TYPES OF RADIOLOGICAL INSTRUMENTS

4.11 In the development of radiologicalinstruments, the choice of detector is animportant factor. An equally importantfactor in their design is the type of infor-mation required by the user. Normallythis information falls into two categories:the measurement of total accumulated ex-posure to radiation, and the instantaneousrate of exposure. The first is referred to asan EXPOSURE MEASUREMENT and the second,as an EXPOSURE RATE MEASUREMENT. As anexample of a situation in which both typesof information are required,'-consider thefollowing. An area is contaminated withfallout. A person is required to enter thearea and not exceed an exposure of 25roentgens. This situation requires an in-strument which will measure the total ac-

.cumulated radiation exposure during theperiod of stay in the contaminated area.Instruments designed to provide suchmeasurements are called DOSIMETERS.Next, assume that the operation to beperformed will require two hours to com-plete. In order to determine if entry intothe area is practical, it is necessary toknow the instantaneous rate of exposureto which the person would be exposed inthe contaminated area. Instruments de-signed to measure exposure rate are calledSURVEY METERS.

4.12 It is important to emphasize thatradiological instruments measure' expo-sures and not absorbed or biological doses.Such EXPOSURE is a measure of thestrength of the radiation field, while theABSORBED DOSE is a measure of the amount

of energy liberated in the absorbing mate-rial, and the BIOLOGICAL DOSE is a measureof the biological effect of a particular ra-diation absorbed by an individual. How-ever, it is also important to emphasizethat the ultimate objective for measuringan exposure to radiation is to relate thatto a certain biological response of the ex-posed individual.

UNITS OF RADIATION MEASUREMENT

4.13 As discussed in Chapter 2, theroentgen is the unit of radiation exposure.This unit is based on the effect of X orgamma radiations on the air throughwhich they pass. It defined as thatquantity of X or gamma radiation suchthat the associated corpuscular emissionper cubic centimeter of dry atmosphericair at 0° centigrade and 760 mm of mer-cury produces, in air, ions carrying oneelectrostatic unit of. barge of either sign(2.083 x 109 ion pairs/cc). Since this unit israther, large for measuring peacetime oc-cupational exposures, the milliroentgen,which is equivalent to 1/1000th of a roent-gen, is frequently used for measuringsmall exposures. Since dosimeters meas-ure exposure, they measure in ROENTGENS

or MILLIROENTGENS, while survey meters,which measure exposure rates, measure inROENTGENS per hour or MILLIROENTGENS perhour. It is important to note that the roent-gen applies only to the -measurement of Xor gamma radiation, and does not apply tothe measurement of alpha or beta radia -.tion.

4.14 These units of exposure and expo-sure rate are related by a time factoranalogous to the relationship between to-tal distance traveled and speed. For exam-ple, the total distance from Battle Creek,Michigan, to Detroit, Michigan, is approxi-mately 120 miles. A person leaving BattleCreek and averaging 40 miles per hourwould require three hours to travel toDetroit. Similarly, if a person entered aradioactive contaminated area where theexposure rate was 40 roentgens per hourand remained for three hours, his totalaccumulated exposure would be 120 roent-gens. This, of course, assumes that the 40

6257

roentgens per hour exposure rate re-mained constant. Just as it is difficult tomaintain a speed of 40 miles per hour, somight it be difficult to maintain a radia-tion field of 40 roentgens per hour, sinceradioactive materials decay according tofixed natural laws. This decay will causethe 40 roentgens per hour exposure rate todecrease with time. However, if the radio-active material has a relatively long half-life, the decrease in exposure rate during athree-hour period may be negligible. (Withfallout, especially in the early hours afterdetonation, the decrease in exposure ratewill be appreciable during a three-hourperiod.)

DOSIMETERS.

4.15 As indicated above, it is necessaryin emergency operations to provide an in-strument capable of measuring an individ-ual's total exposure to radiation. It is clearfrom the definition of the roentgen thatthe measurement of ionization in air isbasic to the determination of radiationexposure. In Civil Preparedness an ioniza-tion chamber employing the principle ofenclosed gas volume has proved most.sat-isfactory for exposure measurement.

4.16 To understand the operation of do-

ELECTRODE

INSULATOR

CASE

5

FOIL LEAVES

FIGURE 4.16a.Charged electroscope.

3

GAMMA

PHOTON

FIGURE 4.16b.Radiation effect on charged -electroscope.

simeters, consider a foil leaf electroscope(Figure 4.16a) consisting of an outsidemetal shell in which is mounted an exter-nally projecting electrode. An insulatorsuch as amber or sulfur insulates the elec-trode from the outside case. Two narrowstrips of a thin foil are cemented to theenclosed stem of the electrod to form themoving part of the electrost, . Normally,windows in the case serve for viewing thefoil leaves. If an electrical charge is ap-plied to the externally projecting elec-trode, it is transferred through the elec-trode to the foil leaves. Because of themutual repulsion of like charges, theleaves will immediately repel each otheruntil the electrical repulsion is justcounter-balanced by the gravitationalforce tending to bring them back together.If the air in the enclosed chamber is ion-ized by radiation (Figure 4.16b), it becomesan electrical conductor and this permitsthe charge on the leaves to leak away.Since the electrical charge is reduced, themutual repulsion of the leaves is reducedand they assume a position closer to-gether. This same principle is basic to theoperation of dosimeters. The electrostaticself-indicating dosimeter used in Civil Pre-paredness is nothing more than a sophisti-cated electroscope.

FIGURE 4.17.Construction principles of an electrostatic self-indicating dosimeter.

4.17 The dosimeter consists of a quartzfiber electrometer suspension mounted in-side an ionization chamber (Figure 4.17).The electrometer suspension is supportedby means of a highly insulated materialinside an electrically conducting cylinder.The enclosed air volume surrounding theelectrometer suspension is the ionizationchamber or the radiation sensitive compo-nent of the instrument. The indicatingelement is a five micron (1/5000 in.) quartzfiber which is part of the electrometersuspension. The quartz fiber has an electr-ically conducting coating evaporated on itssurface and has the same forth factor asthe metal frame of the electrometer. Inmost dosimeters both frame and fiber arein the shape of a horseshoe, the fiber beingattached to two offsets on the lower ex-tremities of the frame.

4.18 The dosimeter contains an electri-cal capacitor in parallel with the electro-meter suspension and the chamber wall.The range of the dosimeter is determinedby the size of the capacitor, the chambervolume, the sensitivity of the electrome-ter, the pressure inside the ionizationchamber and the optical system. Onlypressure and capacitance variation offer awide selection of ranges. Therefore, thefunction of the electrical capacitor is tochange the range of the dosimeter. How-ever, for a particular dosimeter, the rangewill be fixed by the selection of the capaci-tor at the time of its manufacture.

4.19 The charging switch assembly con-sists of a bellows and a contact rod, whichis normally isolated from the electrometer

suspension. Only when the dosimeter isplaced on a dosimeter charger and thebellows depressed can contact be madebetween the rod and electrometer. Thisarrangement provides a very high electri-cal resistance, and the hermetic sealingallowed by such construction makes thedosimeter readings essentially independ-ent of humidity and pressure changes.

4.20 Focused on the quartz fiber is a 75to 125 power microscope which magnifiesthe image of the quartz fiber so that it isvisible. The microscope consists of one ob-jective lens, one eyepiece lens, and con-tains a scale or reticle at the real image ofthe quartz fiber. The scale is graduated inroentgens or milliroentgens depending onthe range of the instrument.

4.21 In preparation for exposure to ra-diation, the dosimeter is charged to about160 to 175 volts to bring the image of thequartz fiber to zero on the scale. (Figure4.21). In charging the dosimeter, an exter-nal source of electrical power is used. Theionization chamber is held at ground po-tential and the metal frame and fiber ofthe electrometer assume the other ex-treme of the voltage difference. The fiberis repelled from the frame since both areat the same potential. The position of thequartz fiber will then vary with the poten-tial difference. This variance is linear forthe voltage range covered by the scale.When the instrument reads full scale, thepotential 'difference is not zero but usuallysome intermediate voltage between 75 and125 volts.

64

59

FIGURE 4.21.Zero dosimeter reading.

4.22 As the dosimeter is exposed to Xor gamma radiation, the photons will in-teract with the wall of the ionizationchamber producing secondary electrons(Figure 4.22a). These electrons enter thesensitive volume of the dosimeter and ion-ize the air molecules. Under the influenceof the electrical field in the chamber, theion pairs migrate to the electrode of oppo-site charge and are neutralized. Thiscauses a proportionate discharge of thecapacitor system and decreases the poten-tial difference between the electrometerand the chamber wall. The quartz fibernow assumes a new position correspondingto the new potential difference. This isreflected by an up-scale movement of the

RECOILELECTRON

INCIDENTPHOTON

FIGURE 4.22a.Operation of an electrostaticdosimeter.

60

160 V

100 V

U5

FIGURE 4.22b.-80 R dosimeter reading.

hairline image of the quartz fiber (Figure4.22b).

The movement of the fiber is a functionof the total amount of radiation to whichthe dosimeter is exposed, regardless of therate of exposure to radiation.

4.23 If the dosimeter reading is zero atthe start of a period, the exposure may beread directly from the dosimeter. How-ever, any initial dosimeter reading mustbe subtracted from the final reading toobtain a correct indication of the totalexposure. For example, if a dosimeterreads 10 rems at the start of a period andreads 55 rems at the end, the exposureduring the period is 45 rems. Performancecharacteristics of dosimeters will be dis-cussed in the next chapter.

DOSIMETER CHARGERS

4.24. The design of dosimeter chargershas progressed to the point that the latermodels all use transistorized circuits toprovide the required charging voltage. Al-though some of the earliest chargers werenot transistorized, probably all futureones will be because of the ease of opera-

CHARGING CONTACT

LIGHT SWITCH OPEN

FIGURE 4.25a.Initial condition.

HARGING SWITCH OPEN

DOSIMETER

LIGHT SWITCH CLOSED

FIGURE 4.25b.Reading position.

CHARGING SWITCH CLOSED

DOSIMETER

/ I \LIGHT SW TCH CLOSED

FIGURE 4.25c.Charging position.

tion of the transistorized models and pro-longed battery life.

4.25 In the transistorized chargers, thecircuit is powered by a single 1.5 volt bat-tery. The charging contact is shown in itsinitial condition in Figure 4.25a. When adosimeter is placed on the charging con-tact and pressure is applied, the lightswitch closes and the bulb lights (Figure4.25b). However, in this position the dosim-eter cannot be charged, since the dosime-ter charging switch is still open. Addi-tional pressure must be applied to cloSethis switch (Figure 4.25c). A transistor os-cillator converts the direct current from aflashlight battery to alternating currentso that the transformer can "step up" thebattery voltage (1.5 volts) to the voltagerequired by the dosimeter. The current is

TRANSISTOR

OSCILLATOR

ld c TO O c)

I 5VOLT

FLASHLIGHT CELL

lA c)

TRANSFORMER

II 5 VOLTS TO

220 VOLTS)

DIODE

RECTIFIER

(is c TO d c)

VARIABLE VOLTAGE

OF 220 VOLTSNAMMuM AVAILABLE

AT CHARGINGWELL

FIGURE 4.25d.Simplified diagram of a CD V-750dosimeter charger.

then rectified by a diode and a potential of220: volts maximum is available at thecharging contact. A voltage control is usedto adjust the output voltage to the exactvalue required to bring the dosimeter tozero.

4.26 The mechanics of charging a do-simeter with this type of charger will bediscussed in the next chapter.

SURVEY METERS

4.27 Our discussions in paragraph 4.11established an additional requirement foran instrument which would measure expo-sure rate for use in survey operations.This instrument should measure the rateof formation of ion pairs* rather than thetotal number that are produced by radia-tion. To date the enclosed gas volume prin-ciple has again proved most satisfactoryfor Civil Preparedness uses.

4.28 There are two types of Civil Pre-paredness exposure rate instrumentswhich depend on the principle of electricalcollection of ions (enclosed gas volume) fortheir operation. The characteristics ofeach depend mainly on the voltage atwhich the enclosed gas volume is operated.To understand their operation, it as neces-sary to investigate the behavior of ions inan electrical field. A ?:.stem for investigat-ing this behavior is illustrated in Figure4.28. It consists of a chamber filled withair in which are fixed two Parallel metalplates to act as electrodes. The electrodesare connected to a battery in such a waythat the voltage can be increased steadily.from zero to several hundred volts. A me-

61

FIGURE 4.28.Circuit for measuring the behavior ofions in an electrical field.

ter is placed in the circuit to measure thesize of the electrical current produced.

4.29 Normally, the air in the ionizationchamber will not conduct electricity andno current will flow in the external circuit.If a single ionizing radiation enters thechamber when a small difference of poten-tial is applied to the electrodes, a numberof ion pairs will be produced which willmove to the oppositely charged electrode.When these charges collect, a currentpulse will be measured by the meter in theexternal circuit. If a constant source ofgamma radiation is used and the size ofthe current pulse is plotted against thevoltage applied to the electrodes, the

RECOPABINATIONCONTINUOUS OISCHARGEi

IONIZATION CHAMBER

PROPORTIONAL

sEIGER i4uLLER

A

GAMMARAYS --e

INCREASING VOLTAGE I*.VOLTAGE APPLIED ACROSS THE CHAMBER

FIGURE 4.29Pulse size vs. applied voltage for gammaradiation.

62

G

curve in Figure 4.29 will result. For con-venience, the curve is divided into fiveregions, A, B, C, D and E.

4.30 When the voltage applied to theelectrodes is low, the electrical accelerat-ing force is small. Thus, the ions moverather slowly and have sufficient time torecombine with other ions of opposite signin the vicinity. The size of the pulse meas-ured will be-less-than if all of the ion pairsformed succeeded in reaching the elec-trodes. As the applied voltage is increased,the ions travel faster. Their chances ofrecombination are lessened and the pulsesize increases. Finally, as the applied volt-age is increased sufficiently, all of theprimary ion pairs will be collected at theelectrodes. This voltage is referred to asthe saturation voltage. As the electrodevoltage increases above this point, no in-crease in the size of current pulse is imme-diately experienced since all of the pri-mary ion pairs have been collected. There-fore, the pulse size remains relatively con-stant throughout region B of the curve inFigure 4.29. The actual voltage range overwhich the pulsesize is constant dependson many factors, which include the gasused in the chamber, the pressure of thegas, and the distance between the elec-trodes.

4.31 Region B of the curve is referredto as Lhe ionization chamber region, andinstruments designed to operate in thisregion are called ionization chamber in-struments. Since batteries. are usuallyused as the source of electrical power inRADEF instruments, this region is welladapted for their use. If the operatingvoltage for a particular ionization cham-ber is chosen at the upper end of theplateau, the size of the electrical pulseproduced by radiation will not vary appre-ciably as the electrode voltage decreaseswith both age and use of the batteries.

4.32 As the applied voltage is increasedbeyond the ionization chamber region, thesize of the pulse is increased. In region Cof the curve, the increased electrical fieldcauses the primary ions to gain sufficientkinetic energy to cause secondary ionisa-tion of other atoms and molecules in thegas. This secondary ionization leads to an

increase in the size of the pulse, whichamounts to an internal amplification ofthe pulse in the enclosed gas volume. Thisamplification increases with applied volt-age and remains linear until an internalamplification factor of approximately 1,000is obtained. Region C is the proportionalregion, and instruments operating in thisregion are called proportional counters.No Civil Preparedness instruments oper-ate in this range.

4.33 In the proportional region, a largenumber of secondary ion pairs are pro-duced at only one point within the en-closed gas volume. However, when the ap-plied voltage is increased further, the sec-ondary ionization occurs throughout theenclosed gas volume. Therefore, since theamplification is so great in the GeigerMuller region, the size of the pulse isalmost independent of the number of ionpairs produced. Thus, one initial ionizingevent occurring within the enclosed gasvolume will initiate an ELECTRON AVA-LANCHE (explained in paragraph 4.46)which will spread quickly throughout theentire tube. Instruments operating in thisregion will produce one large pulse foreach ionizing event to which the tube issubjected. Gas amplification factors of theorder of 100 million are common.

4.34 When the operating voltage ex-ceeds the Geiger Muller region, it is sohigh that once ionization takes place inthe gas, there is a continuous discharge ofelectricity so that it cannot be used forcounting purposes. The upper end of theGeiger Muller regiu-u is -marked by thisbreakdown voltage.

OPERATION OF ION CHAMBER SURVEYMETERS

4.35 The development of ionizationchamber survey meters has also pro-gressed to the point that the later modelsof ionization chamber survey meters andprobably future models will use a modifi-cation of the simplified schematic circuitdrawn in Figure 4.35. The basic compo-nents of this circuit are: (1) an ionizationchamber, (2) a source of electrical power,and (3) a measuring circuit consisting of

an electrometer tube and an indicatingmeter.

4.36 The detecting element of the, in-strument is an hermetically sealed air-equivalent ionization chamber. It consistsof a conducting cylindrical container ofplastic and steel called the shell and a thinconducting disk, which is located in thecenter of the shell, called the collector.These are respectively the positive andnegative electrodes and are insulated fromeach other by an extremely high resist-ance feed-thru insulator. A collecting volt-age is applied to these two chamber elec-trodes.

FIGURE 4.35.Simplified circuit diagram for a CivilPreparedness ion chamber survey meter.

4.37 When the instrument is exposed toradiation, some of the energy of the radia-tion field is absorbed within the walls ofthe ionization chamber. As a result, elec-trons are ejected from the walls into theair contained within the chamber. Asthese electrons traverse the chamber,they create a considerable amount of ioni-zation in the air. Under the influence ofthe electric field existing between thechamber electrodes, the ions move to theelectrode having the opposite charge; that

68

63

is, positive ions move toward the col:cc:I-Augdisk and the negative ions toward theshell. The arrival of these ions at theelectrodes constitutes a current, the mag-nitude of which is proportional to theber of ions collected. Since the number ofions created is proportional to the radia-tion exposure rate, this ionization currentis proportional to the exposure rate in theionization chamber.

4.38 A very small ionization current(approximately 0.00005 microamperes atfull scale on the most sensitive range)flows through 'a "high-meg" resistor anddevelops a measurable voltage.. This volt-age is applied to the grid of a vacuum tubecalled an electrometer tube because it iscapable of measuring voltages at ex-tremely small current values. The electro-meter tube is connected as a triode. Itsthree elements are: (1) Ole filament which,when heated by current from the 1.5 voltbattery, emits electrons, (2) the grid,which controls the flow of these electronsaccording to the voltage applied to it, and(3) the plate, which receives the electronsand passes them to the circuit in the formof a measurable current.

4.39 Measurement of the grid voltageof the electrometer tube is accomplishedby metering the change in plate current(Ip) directly. With the selector switch inthe zero position, the high-meg range re-sistor is removed from the grid circuit sothat no signal voltage can be developed asa result of any ionization chamber cur-rent. The quiescent value of the plate cur-rent is then exactly balanced by the buck-ing current (It) so that the resultant cur-rent through the meter is zero. The buck-ing current is adjusted by means of thezero adjust potentiometer.

4.40 When the selector switch is placedin a range position, one of the high-megrange resistors is reinstated into the gridcircuit. The ionization current, therefore,produces a positive signal voltage acrossthis resistor, which in turn results in anincrease in the plate current. Thus, theresultant current throucii the meter is nolonger zero and the meter measures theincrease in plate current. Since thischange is proportional to the magnitude of64

6

the radiation field, the meter scale can becalibrated directly in roentgens per hour.

4.41 Prior to use for measuring expo-sure rates, the static plate current mustbe cancelled by the reverse filament cur-rent to obtain zero meter current (zeroreading) at zero radiation levels. Since itwill probably be necessary to zero theinstrument in a radiation field, a section ofthe selector switch is used to short out thehigh-meg resistor and prevent any ioniza-tion signal from being sensed by the gridcircuit. Thus, when the selector switch(Figure 4.41) is in the zero position, zeroradiation conditions are duplicated andthe zeroing process can be accomplishedeven in the presence of a high radiationfield.

X100

ZERO -

OFF

CKT CHECK "/

X10

X IX01

0 .1.figiti7713)

ZERO NUIPI

FIGURE 4.41Selector switch and zero control.

4.42 The proper functioning of themeasuring circuit including the batteriesmay be checked by turning the selectorswitch to the circuit check position (Figure4.41) and observing the meter readings. Inthis position, a predetermined voltage isimpressed on the grid of the electrometertube to make the meter read approxi-mately full scale. Deterioration of any ofthe components or batteries in the circuitwill change this reading. Therefore, thisvoltage can be used to check the entirecircuit with the exception of the ionizatonchamber and high-meg resistor.

4.43 All radiological instrumentsshould be calibrated prior to their initialfield use and periodically thereafter. Thismay be done by using a calibrated sourceof radioactive material. If the instrumentdoes not read properly when placed in aradiation field of known exposure rate, thecalibration control can be adjusted to givethe desired meter indication correspond-ing to the known exposure rate.

4.44 Sensitivity of the instrument ischanged by switching high-meg resistors.This is accomplished by the selector switch(Figure 4.41). On each range the meterreading must be multiplied by 0.1, 1, 10,and 100 to obtain the measured exposurerate.

OPERATION OF GEIGER COUNTERS

4.45 Geiger counter operation is basedon the ionization of gases similar to theoperation of ionization chamber surveymeters. In the ionization chamber instru-ment, a very small current is developed,amplified, and then measured on a sensi-tive meter. The current is smooth in char-acter since the many ionizing events areaveraged. Geiger counters differ materi-ally in that the current flow is not smoothbut it is delivered in surges or pulses.

4.46 Geiger counters take advantage ofthe extreme gas amplification that can beobtained when high accelerating voltagesare applied to the electrodes within thechamber. As ion pairs are formed in thegas, they will move with increasing veloc-ity toward the electrodes until either re-combination or collision with another airmolecule occurs. The average distance 'be-tween successive collisions is referred toas the mean free path. If the mean freepath is small and the accelerating voltagerelatively high, each ion will gain only asmall amount of energy between collisions.As the operating pressure of the Geigertube is reduced, the mean free path isincreased, causing the ions to gain addi-tional energy between collisions. When thekinetic energy of the ions is sufficient,they will cause secondary ionization.These secondary ions will also be acceler-ated by the electrical field and will pro-

duce further ionization. This cumulativeincrease in ions, is similar to a single rockprecipitating an avalanche and is, there-fore, often referred to as ELECTRON AVA-

LANCHE. This avalanche may produce asmany as 100 million other ion pairs foreach initial ion pair produced in the cham-ber. The gas amplification factor of thetube under these conditions would beabout 100 million.

4.47 Consider a Geiger tube filled witha gas, frequently argon or neon, to anabsolute pressure of ten centimeters ofmercury and exposed to a constant radia-tion intensity. If the number of pulse's persecond occurring within the tube is plottedagainst the voltage applied to the elec-trodes, a characteristic curve similar toFigure 4.47 is produced. This curve differsfrom the curve in Figure 4.29 in that thenumber of pulses is plotted against theapplied voltag- rather than the size of thepulse. Since, under the operating condi-tions placed on the tube, no gas amplifica-tion occurs at low voltages, there is athreshold below which no pulses will berecorded. As the voltage increases and thegas amplification factor increases, thenumber of pulses increases. At first, onlythe most ionizing particles would becounted and the weak ones lost. As thevoltage increases, however, practically ev-ery particle entering the tube will becounted. When this condition occurs, the

L., I

M u)

ul p.

cc 1 a0

., 0,

cc

IF

APPLIED VOLTAGE

FIGURE 4.47.Number of pulses vs. applied voltagefor a Geiger tube.

65

curve will flatten out. This is called theGeiger plateau and it is desirable that ithe long and flat so that the counting ratedoes not depend strongly upon the appliedvoltage. Above the Geiger plateau voltage,the tube goes into a continuous dischargestate and is not suited for counting pur-poses.

4.48 Avalanche formation will takeplace in the vicinity of the central wire ofthe Geiger tube, since here the electricfield is high and each electron on its wayto the central wire acquires sufficient en-ergy for further ionization in each meanfree path. Thus, a large number of elec-trons and positive ions will be formed nearthe center wire in the first avalanche. Theelectrons having a small mass and alreadypositioned close to the central wire willmove toward it with high velocities andwill be completely collected in about onemillionth of a second. The heavier positiveions travel more slowly out to the nega-tively charged cylinder. This causes a posi-tive ion cloud or space charge which re-duces the electric field and stops the ava-lanche formation. In about one ten thou-sandth of a second, the positive ions orspace charge will reach the cylinder wall.As a positive ion approaches very close tothe cylinder, it will pull an electron fromthe cylinder and be converted to a neutralmolecule. Generally, the electron willmove into one of the upper energy levels ofthe molecule resulting in an excited molec-ular state. The electron will move to theground state and in so doing may producephotons in the ultraviolet region whichwill have sufficient energy to liberate pho-toelectrons from the metal cylinder. Withhigh tube voltages, this single photoelec-tron will start a second avalanche andthus the entire process will be repeatedover and over again. This repeated dis-charge must be stopped and the tube re-stored to its initial condition if the tube isto be used to measure radiation. The proc-ess by which the tube is prevented fromrepeating the discharge is called quench-ing.

4.49. Quenching may be accomplishedeither electronically or by adding a suita-

66

71

ble gas to the Geiger tube. Utilizing asuitable electronic circuit, the operatingvoltage of the Geiger tube can be momen-tarily reduced below the voltage requiredfor a self-perpetuating discharge as soonas the avalanche begins. Other Geigertubes, called self-quenched tubes, utilize asmall amount of alcohol or halogen gas toquench the discharge. In this case, bothargon and alcohol molecules participate inthe avalanche. As the positive ions mi-grate to the electrode, the argon ions hav-ing an ionization potential of 15.7 voltscollide with alcohol molecules with an ioni-zation potential of 11.3 volts. This differ-ence in ionization potential causes thecharge to be transferred to the alcoholmolecules and only these ions reach theelectrode. As they approach the electrode,they will pull electrons from the cylinderwall. The energy of the excited states ofthe alcohol molecules will disassociateother alcohol molecules gather than causefurther ionization. The self-perpetuatingdischarge is prevented in this manner.

4.50 Since some of the quenching gas isdisassociated at each discharge, the sup-ply is constantly depleted and the Geigertube will have a limited useful life of aboutone billion counts. Halogens, particularlychlorine and bromine, are currently beingused as .quenching gases in argon-filled-counters and have some advantages overthe alcohol-quenched tubes. Since the hal-

.

ogen atoms will recombine after the disas-sociation process, tubes filled with this gaswill have essentially an unlimited life.Halogens, however, are extremely reactivegases and great care must be exercised inchoosing electrode materials.

4.51 Figure 4.51 illustrates a typicalsimplified circuit diagram of a Geigercounter. The Geiger tube consists of a thincylindrical shell which serves as the cath-ode, a fine wire anode suspended along thelongitudinal axis of the shell, and a smallamount of a quenching gas. A potential ofapproximately 900 volts is applied betweenthe two electrodes.

4.52 When radiation penetrates thetube, a gas molecule is ionized. The result-ing ion pair is accelerated toward the elec-trodes by the electric field. Because of the

high accelerating voltages, the creation ofadditional ions is very rapid, thus produc-ing a discharge (avalanche) in the tube.This discharge results in a pulse in the

FIGURE 4.51.Simplified circuit of a Geiger counter.

external circuit. The frequency of suchpulses is proportional to the strength ofthe radiation field. The small amount ofhalogen gas in the tube serves to stop eachdischarge and restore the tube to its ini-tial condition.

4,53 The pulse output from the Geigertube is amplified by conventional elec-tronic means and then measured by asensitive meter which sums up the radia-tion effects in the form of a reading ineither counts per minute or, in the case ofgamma rays, milliroentgens per hour. Inaddition to the meter indication, mostGeiger counters are provicred with head-phones which detect the pulses from theGeiger tube and produce an audible click.

REFERENCES

Sourcebook on Atomic Energy.Glas-stone, Samuel, D. Van Nostrand, 1967.

Nuclear Radiation Physics.Lapp,Ralph E. and Andrews, Howard L., Pren-tice-Hall, Inc., 1972.

7?

67A

RADIOLOGICAL EQUIPMENT

Having covered the theory of radiologi-cal instrumentation in the previous chap-ter, we are ready to move to the practicalaspects of detecting and measuring nu-clear radiation. This means it is time for alook at the various types of radiologicalequipment available and the different sit-uations in which each item would be ap-plied. In addition to learning what wehave in the way of different pieces ofequipment, we will also be shown:

WHAT the equipment can doWHAT it cannot doWHEN to use a particular piece of

equipmentHOW to check it, operate it and care

for it

RADIOLOGICAL INSTRUMENTREQUIREMENTS

5.1 There is no exact equivalent of com-bat; experience upon which to base therequirements for Civil Preparedness ra-diological equipment. However, extensivetests of nuclear weapons under knownconditions have indicated the kinds andextent of residual radiation that could re-sult from the use of such weapons. Theknowledge gained from these and othertypes of experiments makes it possible torelate radiation conditions to biological ef-fects on man and thus establish equip-ment requirements.

5.2 Because of the many variables as-sociated with the detonation of a nuclearweapon, it is not possible to predict accu-rately the radiation levels that will resultfrom fallout. Furthermore, no single in-strument meets all of the operational re-quirements that might result from a nu-clear attack. Therefore, a wide capabilityfor radiation measurement is required.

73

CHAPTER 5

DCPA has developed several instrumentsthat, together, provide this wide monitor-ing capability. These instruments fall intotwo distinct classes:

Radiation survey meters for use by mon-itoring personnel in determining contami-nated areas and radiation exposure rates.

Exposure measuring instruments (do-simeters) needed by all Civil Preparednessworkers such as fire fighters, first aiders,rescue teams, and radiation monitors whohave to perform their emergency duties incontaminated areas.

5.3 SURVEY METERS provide the informa-tion required for locating contaminatedareas and for estimating the degree of thehazard. Since it would not be practical tocompute your total radiation exposurefrom survey meter measurements if theexposure rate varied during the exposureperiod, DOSIMETERS are also needed for re-cording the total amount of an individual'sexposure. Estimates of total exposure andreiated biological effects can be made onthe basis of exposure rate measurements,decay rates, and probable exposure times,but these estimates should be used forplanning purposes only. Determinationµ ofactual exposure times and exposures dur-ing emergency operations must be basedon both the exposure rate, as read onsurvey meters, and on the total exposureas indicated by dosimeters.

5.4 Alpha, beta, and gamma radiationsmay be present in radioactive fallout.Since the hazards from these radiationswill be discussed in detail in later chap-ters, it suffices here to indicate thatgamma radiation is an external hazardand, under certain conditions, beta radia-tion may also be an external hazard. Inaddition, these three types of radiationmay be internal hazards.

69

5.5 Alpha radiation does not present anexternal hazard, since it will not penetratebeyond the surface layers of the skin. Al-pha emitters must get inside the bodybefore they can cause appreciable damage.Because alpha emitters will probably notpresent a significant hazard relative tothe beta and gamma hazard immediatelyfollowing a nuclear attack and for sometime thereafter, and further, because ofthe difficulty in developing portable alphameasuring instruments, DCPA does notprovide a standard instrument sensitive tothis type of nuclear radiation. During therecovery phase, the determination of theseriousness of the alpha contamination infood and water will probably be accom-plished by laboratory-type instruments.

MEASURING BETA AND GAMMARADIATION

5.6 Since the biological effects of betaand gamma radiation differ, radiologicalinstruments must discriminate betweenthem. Measurement of beta radiation iscomplicated by the very wide range ofenergies of these particles. Most beta de-tection instruments will not respond toextremely low energy beta particles. How-ever, that portion of the beta radiationthat can be detected should be detected, sothat its proportion to the total radiationexposure can be determined. This is neces-sary to estimate possible damage by eachtype of radiation. It should be noted, how-ever, that the units of measurement usedon radiological instruments to show accu-mulative exposures and exposure rates ofgamma radiation are the roentgen and theroentgen per hour and the roentgen isdefined in terms of X or gamma radiationexposure in air. Therefore, these units donot relate directly to measurements ofbeta radiation. Consequently, meter indi-cations of beta radiation can be inter-preted only in a general way.

5.7 The sensitivity requirement of a ra-diation instrument depends upon the typeof information it is expected to provide. Aninstrument used to measure the contami-nation of personnel, food, water, equip-ment, or living quarters must indicate70

very small amounts of radiation abovenormal background radiation. This type ofinstrument would therefore have little usein areas of heavy contamination.

5.8 To provide adequate monitoring,portable radiological instruments shouldbe capable of measuring gamma exposurerates as high as 500 R/hr and also indicatewhen exposure rates exceed this figure.Measurement above this amount is notnecessary for portable survey instru-ments, because a higher level of radiationwould be so dangerous as to preclude fur-ther surface operations.

5.9 When surface level expostire ratesare very high or when rapid monitoring oflarge areas is required, aerial monitoringmay be practical. Survey meters designedfor this purpose must be extremely sensi-tive in order to give correct readings ofradiation levels on the ground. Remotereading instruments used to indicate ra-diation levels outside fallout shelters arealso required and should indicate gammaexposure rates up to at least 500 R/hr.

5.10 Within the entire group of radiol-ogical instruments developed by DCPA,the capability exists for measurement ofionizing radiation exposure rates rangingfrom a minimum of natural backgroundradiation to a maximum of 500 R/hr. Thiswide range of measurement capability isconsidered adequate for all operationalneeds.

TYPES OF DCPA RADIOLOGICALINSTRUMENTS

5.11 Each of the DCPA radiological in-struments will be dvscussed in terms of itsuses, significant operating characteristics,important specifications, and the care andmaintenance to be accomplished by theinstrument operator or monitor.

CD V-700

5.12 The CD V-700 radiation surveymeter (Figure 5.12) is a highly sensitivelow-range instrument that can measuregamma radiation and discriminate be-tween beta and gamma radiations. DCPArecommends its use primarily in long-termclean-up and decontamination operations.

b

CD

FIGURE 5.12.CD V-700, low range beta-gammasurvey meter,

5.13 The instrument can also be used intraining programs where low radiation ex-posure rates will be encountered. The de-tecting element of the CD V-700 is aGeiger tube shielded so that only thegamma exposure rate is measured or betaand gamma can be detected together withthe shield open. A headphone for audibleindication is supplied with this instru-ment.

IMPORTANT SPECIFICATIONS OF THE CD

V-7001. RANGE: 0-0.5, 0-5.0, 0-50 milliroent-

gens per hour.2. DETECTS: beta and gamma radiation.3. ACCURACY: ± 15% of true exposure

rate from cobalt 60 or cesium 137.4. RESPONSE TIME: 95% of final reading

in approximately 8 seconds.5. TEMPERATURE: instrument shall oper-

ate properly from 10° F to + 125° F.6. PRESSURE: instrument shall operate

properly from sea level to 25,000 feet.7. JAMMING: exposure rates from 50 mil-

liroentgens per hour to 1 roentgen perhour shall produce off-scale readings.

8. LIGHT SENSITIVITY: direct sunlightshall not affect the operation of theinstrument.

9. ELECTROMAGNETIC INTERFERENCE:the instrument shall operate properlyin normally encountered electromag-netic fields.

10. OPERATIONAL CHECK SOURCE: a per-manently sealed radioactive sourceshall provide a reading of 2 mR/hr ±0.5 mR/hr when the probe, with betashield open, is held over it.

11. BATTERY LIFE: 100 hours continuoususe (minimum).

OPERATOR USE, CARE ANDMAINTENANCE OF THE CD V-700

5.14 Batteries.Whenever the instru-ment fails to respond to the radioactivesource on the side of the instrument, checkthe batteries. Replace bad batteries in ac-cordance with the instructions in the man-ual accompanying the instrument.

During extended storage periods thebatteries should be removed from theinstrument and stored in a cool, dryplace.Battery contacts should be inspected

monthly, and any dirt or corrosion presentshould be removed. Whenever the instru-ment is not in use, MAKE CERTAIN IT ISTURNED OFF; otherwise, the batterieswill be depleted and the instrument ren-dered ineffective.

5.15 Geiger Tube.The Geiger tubes inthe later models of the CD V-700 are halo-gen quenched so that their operating We-is unaffected by use and, therefore, rarelyrequire replacement. However, when freshbatteries are installed and the instrumentdoes not work correctly, it may be neces-sary to replace the Geiger tube. To checkfor a faulty Geiger tube, replace the sus-pected tube with a good tube from a prop-erly operating CD V-700.

5.16 Headphones.If the operatorchooses to use the headphones with theinstrument, they may be screwed into theconnector provided at the lower left cornerof the instrument cover. In using theheadphone, the operator will note thateach pulse or count is indicated by a dis-tinctly audible click. When the headphonesare not in use, the protective cap on theheadphone receptacle should be replaced.

71

5.17 Carrying Strap.The instrumentmay be carried in the hand or by a strapover the shoulder. The strap anchors arearranged in such a way that the meter isvisible when carried over the right shoul-der.

5.18 Controls.There is only one con-trol on this instrument for the operator'suse. This control, called the selectorswitch, includes an off position and threeranges, labeled X 100, X 10, and X 1. Onthe X 1, the X 10 and X 100 ranges, themeter readings must be multiplied by afactor of 1, 10, and 100, respectively, toobtain the measured exposure rate.

5.19 Operational Check.The selectorswitch should be turned to the X 10 range.The beta shield on the probe should berotated to the fully open position and theprobe placed as close as possible to theradioactive sample located either on thebottom surface of the case or underneaththe manufacturer's name plate (see in-strument manual). The open area of theprobe must be directly facing the radioac-tive sample. The meter should be adjustedto read 2 ± .5 milliroentgens per hour. Noexternal radiation must be present whenmaking this check. The source should beused to determine the operability of theinstrument only. It is not intended to re-place the need for calibrating the instru-ment against a known source.

5.20 Calibration.The instrumentshould be calibrated periodically to verifythat it is measuring correctly.

5.21 Contamination.At all times theoperator should attempt to prevent radiol-ogical contamination of the instrument,particularly of the probe. In case of con-tamination, the instrument can be cleanedby a cloth dampened in a mild soap solu-tion.

CD V-715

5.22 The CD V-715 (Figure 5.22) is ahigh-range gamma survey meter for gen-eral postattack operational use. The de-tecting element of the CD V-715 is an 9.ionization chamber. The instrument is de-signed for ground survey and for use infallout shelters. It will be used by a radiol-

FIGURE 5.22.CD Y.,715, high-range gamma surveymatter.

ogical monitor for the major portion ofsurvey requirements in the period immedi-ately following a nuclear weapon attack.The CD V-715 has replaced the now obso-lete CD V-710 medium-range 0-50 R/hrgamma survey meter.

IMPORTANT SPECIFICATIONS OF THE CDV-715

1.

2.

3.

4.

5.

6.

7.

8.

72

RANGE: 0-0.5, 0-5.0, 0-50, 0-500 roent-operate from 20° F. to 110° F.

DETECTS: gamma radiation only.ACCURACY: ± 20% of true exposure ratefrom cobalt 60 or cesium 137.SPECTRAL DEPENDENCY: ± 15% forgamma radiation energies between 80keV and 1.2 MeV.RESPONSE TIMES: 95% of final readingin 9 seconds.TEMPERATURE: instrument shall oper-ate properly from 20° F to + 125° F.PRESSURE: instrument shall operateproperly from sea level to 25,000 feet.JAMMING: exposure rates from 500roentgens per hour to 5,000 roentgensper hour shall produce off-scale read-ings at the high end.ELECTROMAGNETIC INTERFERENCE: in-strument shall operate properly in nor-mally encountered electromagneticfields.

OPERATOR USE, CARE ANDMAINTENANCE OF THE CD V -715

5.23 Batteries.Battery replacement isnormally required whenever the instru-ment can no longer be zeroed or when themeter indicates below the "CIRCUITCHECK BAND". Batteries should be re-placed in accordance with the instructionin the instrument manual. If the instru-ment is to be stored for more than a fewweeks, the batteries should be removed andstored in a cool dry location. For instru-ments in continuous use, batteries shouldbe removed monthly and the battery con-tacts cleaned of any dirt or corrosion pres-ent.

5.24 Controls.Two controls are pro-vided. One control, the selector switch, hasseven positions: circuit check, off, zero, X100, X 10, X 1, and X 0.1 ranges. On the X0.1, X 1, X 10, and X 100 ranges, the meterreadings must be multiplied by a factor of0.1, 1, 10, and 100 respectively in order toobtain the measured exposure rate. Thesecond control, the zero control, is used toadjust the meter reading to zero during anoperational check.

5.25 Carrying Strap.The instrumentis equipped with a carrying strap whichmay be adjusted to any length to suit theoperator.

5.26 Operational Check.Turn the se-lector switch to the zero position, wait aminute or two for the electrometer tube towarm up and adjust the zero control tomake the meter read zero. Turn the selec-tor switch to the circuit check position.The meter should read within the redband marked "Circuit Check". As the se-lector switch is turned through the zeroposition to the four ranges, recheck thezero setting. Turn the selector switch tothe X 100, X 10, X 1, and X 0.1 range.When no radiation is present, the readingshould not be more than two scale divi-sions up scale. If difficulty is encounteredwith any step in the operational check,refer to the instrument manual for correc-tive procedure. Many models have inter-nal adjustments which may, correct thedifficulty. During normal use, the CD V-

715 should be zeroed frequently, at leastevery half hour.

5.27 Calibration.The CD V-715should be calibrated periodically to verifythe accuracy of its measurements.

5.28 Contamination. The operatorshould attempt to prevent radiologicalcontamination of the instrument at alltimes. In case of contamination, the in-strument can be cleaned by a cloth damp-ened in a mild soap solution.

5.29 Modification (CD V-717).Someof the CD V-715's are equipped by themanufacturer with a removable ionizationchamber attached to 25 feet of cable. Thismodification, called the. CD V-717, pro-vides a remote reading capability for fal-lout monitoring station's. The operatingcharacteristics are identical to the CD V-715 except that the removable ionizationchamber must be placed outside the shel-ter in an unshielded area and protectedfrom possible- contamination by placing itin a bag or covei-of light-weight material.All readings may then be observed fromwithin the fallout monitoring station.After the early periods of heavy falloutand the requirement for a remote readinginstrument diminishes, the removable ion-ization chamber should be checked for con-tamination with the CD V-700, decontami-nated if necessary, and returned to thecase. The CD V-717 may then be used forother monitoring operations.

FIGURE 5.29.CD V-717, Remote Ion Chamber.

73

FIGURE 5.30.CD V--720, beta-gamma survey meter.

CD V-720-

5.30 The CD V-720 (Figure 5.30) is ahigh range (0-500 R/hr) beta-gamma sur-vey meter designed for postattack use bymonitors. It will be used in high-level con-tamination areas where civil preparednessoperations are necessary and for makinghigh-level beta radiation determinations.Many of the Federal agencies maintain asizeable number of these instruments tofulfill their special requirements. The de-tecting element of the CD V-720 is anionization chamber, shielded so thatgamma radiation only can be measured, orboth beta and gamma can be detected withthe shield open.

OPERATOR USE, CARE ANDMAINTENANCE OF THE CD V-720

5.31 The use, care, and maintenance ofthe CD V-720 are similar to the use, care,and maintenance of the CD V-715. (Referto paragraphs 5.23 to 5.28 for details.)

CD DOSIMETERS

5.32 Personnel who must work in con-taminated areas require radiation inte-grating instruments to keep them continu-ously informed of their exposure. For thispurpose DCPA recommends the use of theself-indicating quartz-fiber electrostaticdosimeter (Figure 5.32).74

FIGURE 5.32.CD operational dosimeters.

5.33 DCPA has procured three dosime-ters for operational use. These are the CDV-730, with a range of 0-20 roentgens, theCD V-740, with a range of 0-100 roentgens,and the CD V-742, with a range of 0-200roentgens. The CD V-730 is used when amonitor expects small repeated exposuresover a long period of time. The CD V-740and CD V-742 dosimeters are recom-mended for use when personnel could beaccidentally exposed to large doses of ra-diation. They should be used when person-nel are required to enter fields of highradiation or remain in low radiation fieldsfor long periods during postattack sur-vival and recovery missions. After currentstocks of the CD V-730 and CD V-740 aredepleted, DCPA will procure and issue theCD V-742 only. For training purposes, theCD V-138 with a range of 0-200 milliroent-gens is recommended.

IMPORTANT SPECIFICATIONS OF THE CDDOSIMETERS

1. RANGE: CD V-138 0-200 milliroent-gensCD V-730 0-20 roentgensCD V-740 0-100 roentgensCD V-742 0-200 roentgens

2. DETECT: gamma radiation.

78

3. ACCURACY: ± 10% of true exposuresfrom cobalt 60 or cesium 137

4. SPECTRAL DEPENDENCY: ± 20% of trueexposure for gamma radiation energiesbetween 50 keV and 2 MeV.

5. ELECTRICAL LEAKAGE: CD V-730 andCD V-742. Beginning ten minutes afterexposure, leakage shall not exceed 5% offull scale in a four-hour period. Begin-ning 48 hours after exposure, leakageshall not exceed 2% of full scale in 96hours.CD V-740. Leakage shall not exceed 2%of full scale in 24 hours.CD V-138. Beginning 10 minutes afterexposure, leakage shall not exceed 5%of full scale in 4 hours. Beginning 48hours after exposure, leakage shall notexceed 3% of full scale in 48 hours.

6. GEOTROPISM: reading shall not varymore than ±4% of full scale when ro-tated about the horizontal axis.

7. TEMPERATURE: instrument shall oper-ate properly from 40° F to +150° F.

8. PRESSURE: instrument shall operateproperly from sea level to 25,000 feet.

9. SHOCK: instrument shall operate prop-erly after four drops from a height offour feet onto a hard wood floor.

OPERATOR USE, CARE ANDMAINTENANCE OF THE DOSIMETER

5.34 Maintenance. No maintenanceshould be performed by the user on theself-indicating electrostatic dosimeters.

5.35 Care.When the instruments arereceived, the operator should check theability to zero the dosimeter, check itsresponse to radiatioa, and check its electr-ical leakage characteristics. When usingthe dosimeters, the operator should keepthe hairline as close to zero as possibleand should prevent dosimeter frombecoming contaminated. When not in use,the dosimeters should be charged and sto-red in a dry place.

5.36 Since most electrostatic dosime-ters will require a "soak-in" charge afterlong-term storage in an uncharged condi-tion, such dosimeters should be chargedand the reading observed for a few hours

FIGURE 5.37.CD V-750, dosimeter charger.

before use. A second charging may be re-quired before the instruments are readyfor operation.

CD V-750

5.37 The CD V-750 dosimeter charger isused to read and charge self-indicatingelectrostatic dosimeters (Figure 5.37). Astandard 1.5 volt flashlight cell is used asthe source of electrical power.

IMPORTANT SPECIFICATIONS FOR THE

CD V-750

1. LIGHT SOURCE: instrument must pro-vide illumination for reading and/orcharging the dosimeter.

2. TEMPERATURE: instrument shall oper-ate properly from 20° F to +125° F.

3. PRESSURE: instrument shall operateproperly from sea level to 25,000 feet.

4. SHOCK: instrument shall operate prop-erly after 6 four-foot drops onto a hardwood floor.

OPERATOR USE, CARE ANDMAINTENANCE OF THE CD V-750

5.38 Batteries.The 1.5 volt flashlightcell should be replaced when the lampdims`noticeably on actipting the chargingswitch. Replace bad batteries in accord-ance with instructions in the instrumentmanual. WHENEVER THE INSTRU-

7 5

75

MENT IS STORED FOR MORE THAN AFEW WEEKS, THE BATTERY SHOULDBE REMOVED TO PREVENT POSSIBLEDAMAGE.

5.39 Operations.To read a dosimeter,remove the dust cap from the chargingcontact; place the dosimeter on the charg-ing contact, and press lightly to light thelamp. Read the dosimeter and replace thedust cover when finished. The dosimetermay also be read by holding it toward anylight source sufficient to illuminate thehairline. To charge a dosimeter follow theprocedure printed on the CD V-750.

CD V-457

5.40 The CD V-457 (Figure 5.40) is aGeiger counter which has been especiallydesigned for classroom demonstration use.It operates on a normal 110 volt AC powersupply and produces both visible and audi-ble responses to nuclear radiation. Theinstrument is used in teaching basic nu-clear radiation physics and for decontami-nation demonstrations.

v. to 0FIGURE 5.40.CD V-457, classroom demonstration

unit.

CD V-778

5.41 The CD V-778 30 millicurie Train-ing Source Set consists of six Cobalt 6076

8 0

FIGURE 5.41.Sealed source capsules, open andsealed.

sealed sources (Figure 5.41) and accessoryequipment. It should be noted that thisTraining Source Set has been designedspecifically for use in training exercisesand is not intended as an accurate calibra-tion source.

5.42 The CD V-778 Training Source Setconsists of the following items:

6-5.0 mCi Cobalt 60 Sealed Sourcestotaling 30 mCi, CD V-784

1Lead Container, small (CD V-791)1Lead Container, medium (CD V-

792)` ,-,-2---Locks for Lead Container CD V-792

1Long-Handled Tongs for HandlingSources (CD V-788)

8Radiation Area Signs2-0-200 mR Dosimeters (CD V-138)1Dosimeter Charger (CD V-750)1Geiger Counter (CD V-700)

CD V-794

5.43 The CD V-794 (Figure 5.43) is acalibration unit containing a Cesium 137source of approximately 130 curies. Theprimary shield is composed of depleteduranium, and is shaped to beam the radia-tion from the radioactive cesium into ashielded exposure chamber. Interposed inthe radiation beam path is an attenuatordisk by means of which radiation levels of0.4, 4, 40, and 400 R/hr are produced in theexposure chamber. Jigs are provided to

ar *$17,,,,

CD

FIGURE 5.42.CD V-778, Training Source Set.

49!

properly position the instruments during beamed vertically. The aperture is nor-calibration. The range switch and calibrat- mally closed by a tungsten plug which ising potentiometers are adjusted throughflexible linkages leading outside of the ex-posure chamber. The unit is designed toprovide suitable protection from radiationhazards to the operator.

CD V-757

5.44 The Barrier Shielding Demonstra-tor Set, CD V-757, is a low range radiationdetection instrument coupled to a neonlighted remote readout indicator that isreadily visible in large conference roomsor small auditoriums. With the large indi-cator, a lecturer can show how radiationfrom a radioactive source is affected bydistance and shielding.

A small amount of cesium 137, whichgives off gamma rays, is housed in a leadball mounted in the demonstration plat-form. A tiOle in the platform leads to thecesium source, and gamma radiation is FIGURE 5.43.CD V-794, calibration unit.

77

1114:10

RADIATION).AREA

3,

FIGURE 5.44.-CD V-757.

padlocked in position. Mounted directlyover the hole is a Geiger Muller tube,thatis in the radiation beam when the tung-sten plug is removed.

By placing a radiation absorbing mate-rial over the platform hole, the intensity ofthe radiation beam is attenuated, result-ing in a lower exposure rate readout. Com-parison of radiation absorbing materialscan readily be made by placing them inthe radiation beam.

The relatively simple mathematical rela-tionship that exists for distances from apoint source is demonstrated by doublingthe distance between the detector andsource, and observing the effect upon theradiation level on the large indicator.

CD V-781

5.45 The CD V-781, Aerial Survey Me-ter (Figure 5.45), is designed for limited78

postattack operational use in slow low-flying aircraft. The CD V-781 will be usedby specially trained monitors. The fourmajor components of the CD V-781 aerialsurvey set are: detector unit (threeGeiger-Mueller tubes); metering unit withthree range dials (0-0.1 R/hr, 0-1.0 R/hr,and 0-10 R/hr); simulator unit with dialscorresponding to the metering unit; and amagnetic tape recorder.

IMPORTANT SPECIFICATIONS OF THE CDV-781

1. RANGE: 0-0.1, 0-1.0, and 0-10 roent-gens per hour.

2. DETECTS: gamma radiation only.3. ACCURACY: -±.10% of true exposure rate

from Cobalt .6ft or Cesium 137.4. CALIBRATION: is performed by the

State maintenance shops.

82

5. TEMPERATURE: the instrument willoperate from 20° F. to 110° F.

6. HUMIDITY: to 95%.7. 'ALTITUDE: to 20,000 feet; preferably

'below 1,000 feet.8. OPERATING TIME: 40 hours on nine

flashlight batteries ("D" cells).9. TRACKING ERROR: between the simula-

tor dials and the metering dials shallnot be more than 10%.

10. READING TIME: not less than 15 sec-ondspreferably 1 minute.

11. SHOCK AND VIBRATION: instrument isdesigned to withstand normal shockand vibration encountered in smallaircraft operation.

12. DETECTOR 'UNIT: contains threeGeiger-Mueller tubes similar to the CDV-700. The detector unit should becarefully handled when installing bat-teries.

13. WARMUP TIME: 2 minutes.

OPERATIONAL CHECK PROCEDURES

5.46 Metering Unit.Prior to mounting

TAPE RECORDER

SPARE TAPE REELS

L

the metering unit into the aircraft, theinstrument should be operationallychecked with the use of the simulator unit.The following procedures should be used:

1. Attach the cable of the metering unitto the connector provided on the sim-ulator unit.

2. Position the power switch on the me-tering- unit to "Battery" power posi-tion and allow the instrument a war-mup period of at least 2 minutes.

3. By rotation of the meter-reading con-trol knob on the simulator unit, checkeach of the three meters at half scale.

4. Starting with the metering controlknob in the extreme counterclockwiseposition, slowly rotate the knob clock-wise. The tracking error between themeters of the simulator unit and cor-responding meters on the meteringunit should be no more thari 10% atany simulated exposure rate.

5.47 The audio output may be checkedby plugging in the headset to the meteringunit. The audio output should be from 225

DETECTOR. UNfT

M T G HARDWARE

REMOTE SWITCH

THROAT MICROPHONE

f,

EMPTY TAPE REELS

POWER JACK

SIMULATOR UNIT

METERING UNIT

FIGURE 5.45.Aerial survey meter, CD V-781, model 1

6 0

HEADPHONES

79

to 275 cycles per second (within one or twonotes of middle C) for normal radiationbackground. The audio output can be oper-ated with the simulator unit,

5.48 After installation of the CD V-781Aerial Survey Meter into the aircraft, theoperational check is performed as follows:

1. Instrument Battery Supplya. Observe meters prior to turning on

instrument. Meters should indi-cate zero within one scale division(the instrument has no zero ad-justment).

b. Position the power switch on themetering unit to the "Battery"power switch position and allowthe instrument a warmup period ofat least 2 minutes.

c. Observe the meters after warmupperiod. Meters should continue toindicate zero within one scale divi-sion when only normal backgroundradiation is present. In the eventexternal radiation from falloutprohibits this check, it should be,assumed the instrument.is operat:ing properly if it indicates radia-tion levels above normal back-ground.

d. Press the "Battery Check" switch.The 0-0.1 R/hr meter should read

80 84

at, or slightly above, the batterycheck point.

2. Aircraft Power Supplya. When the aircraft electrical power

source is used, position the powerswitch on the metering unit to the"Plane" power position.

b. Repeat steps c and d above.

THE TAPE RECORDER

5.49 The manufacturer's manual sup-plied with the recorder indicates precau-tions to be observed and provides detailedinstructions for operation. A monitor ex-pecting to use the recorder should practiceusing it until he is proficient both on theground and in flight. The recording andplayback of preliminary survey informa-tion will provide a check of the recorder'soperability. Prior to a mission, the "Bat-tery Voltage Indication" should be ob-served and batteries replaced, if required.

REFERENCES

Handbook for Radiological Monitors.FG-E-5.9, April 1963. Instrument manualsaccompanying each instrument-

Handbook for Aerial Radiological Moni-tors.FG-E-5.9.1, July 1966.

RADIOACTIVE FALLOUT

Now we are ready for a closer look at ourenemyRADIOACTIVE FALLOUT. Wehave learned how it is produced through anuclear detonation and we have learnedhow to measure it when it arrives. Thisprompts a question:

Must we wait until fallout actually ar-rives before we can decide where it isgoing and what to do about it?

. . . and the answer is . . .

NO! ! !

True enough, we cannot detect nor canwe measure fallout before it arrives but wedefinitely do not have to just sit and waitfor it. Although it may appear that thefallout makes its own rules, its movementis affected by a number of elements, someof which we can measure. This lets usmake predictions about the behavior offallout, to estimate its location. In short,when we take our close look at fallout inthis chapter, we will see how RADEF tech-niques can provide life-saving and morale-supporting warnings of the direction offallout movement. We will see:

WHY

HOW

HOW

WHATWHEREWHEN

there is falloutfallout is formedit is spreadinfluences that spreadis fallout most likely to landto expect it

INTRODUCTION

6.1 "Fallout" is one of those wordswhich define themselves. Say the word,and you have grasped its essential mean-ing; the fallback to earth of radioactiveparticles produced by the detonation of anuclear weapon. It is only when we begin

CHAPTER 6

to learn more about fallout that we startto lose sight of this central and simpleidea. Words like "clean bomb" and "dirtybomb"; "early fallout" and "worldwide fal-lout"; "fission products" and "fusion prod-ucts"; "local fallout" and "late fallout";"surface b'urst" and "air burst"; "stron-tium 90" and "carbon 14" make us wonderif we know what fallout is after all, despitethat built in definition. So, let us look atthese words and see what they mean.

SOURCES OF RADIOACTIVE MATERIAL

6.2 Let us first consider where the ra-dioactive material in fallout comes from?How many sources are there and are allequally important?

6.3 When uranium or plutonium are fis-sioned the heavy atoms are split intosmaller atoms and a vast amount of en-ergy is released. Millions upon millions ofthese atomic nuclei are split or fissioned inthe explosion of a nuclear weapon. About200 different isotopes of about 35 elementsare produced as fission products. Most ofthese are radioactive, decaying by emis-sion of beta particles frequently accom-panied by gamma radiation. These fissionproducts constitute the largest singlesource of radioactive material in the fal-lout.

6.4 What about the radioactivity of thefusion products? The different fusion reac-tions used in fissionfusion type weaponsmay produce tritium (a radioactive hydro-gen isotope) and the neutrons produced inthe reaction may cause the formation ofradioactive carbon (carbon 14) from thenitrogen in the air. However, the carbon14 produced is small relative to that nor-mally present in the atmosphere. Only in-sofa as possible genetic effects might the-oretically be incurred over the next sev-

85

81

eral thousand years could carbon 14 ortritium be con-idered possible hazards.Otherwise, fusion products are neglectedas an important source of radioactive ma-terial contributing to the immediate post-attack survival problem.

6.5' The uranium and plutonium whichmay have escaped fission in the nuclearweapon represent a further possiblesource of residual nuclear radiation. Thefissionable isotopes of these elements emitalpha particles and also some gamma raysof low energy. However, because of theirvery long half-lives, the activity is verysmall compared with that of the fissionproducts.

6.6 It will be seen later that the alphaparticles from uranium and plutonium, orfrom radioactive sources in general, arecompletely absorbed in an inch or two ofair. This, together with the fact that theparticles cannot penetrate ordinary cloth-ing, indicates that uranium and plutoniumdeposited on the earth do not represent aserious external hazard. Even if they ac-tually come in contact with the body, thealpha particles emitted are unable to pen-etrate the unbroken skin.

6.7 The last source of radioactive mate-rial to be considered is the neutron in-duced activity. The neutrons liberated inthe fission process, but which are not in-volved in the propagation of the fissionchain, are ultimately captured by theweapon materials through which theymust pass before they can escape, by ni-trogen (especially) and oxygen in the at-mosphere, and by various elements pres-ent in the earth's surface. As a result ofcapturing neutrons, substances may be-come radioactive. They, consequently,emit beta particles, frequently accom-panied by gamma radiation, over an ex-tended period of time following the explo-sion. Such neutron-induced activity, there-fore, is part of the residual nuclear radia-tion.

6.8 The activity induced in the weaponmaterials is highly variable, since it isgreatly dependent upon the design orstructural characteristics of the weapon.

. Paragraphs 6.5 through 6.18 are reprints of sheeted paragraphs.A -_,..cfrRIn The Effects of Nucieur Weapons.

82

8

Any radioactive isotopes produced by neu-tron capture in the residues will remainassociated with the fission products. Inthe period from 20 hours to 2 weeks afterthe burst, depending to some extent uponthe weapon materials, such isotopes, asuranium-237 and 239 and neptunium-239and 240 can contribute up to 40 percent ofthe total activity of the weapon residues.At other times, their activity is negligiblein comparison with that of the fissionproducts.

6.9 An important contribution to theresidual nuclear radiation can also arisefrom the activity induced by neutron cap-ture in certain elements in the earth andin sea water. The extent of this radioactiv-ity is highly variable. The element whichprobably deserves most attention, as faras environmental neutron-induced activ-ity is concerned, is sodium,.. Although thisis present only to a small extent in aver-age soils, the amount of radioactive so-dium-24 formed by neutron capture can bequite appreciable. This isotope has a half-life of 15 hours and emits both beta parti-cles, and more important, gamma rays ofrelatively high energy.

6.10 How much radioactive material isavailable for distribution as fallout?

6.11 At 1 minute after a nuclear explo-sion, when the residual nuclear radiationhas been postulated as beginning, thegamma-ray activity of the 2 ounces of fis-sion products from a 1-kiloton fission yieldexplosion is comparable with that of about30,000 tons of radium in equilibrium withits decay products. It is seen, thereforethat for explosions in the megaton-energyrange the amount of radioactivity pro-duced is enormous. Even though there is adecrease from the 1-minute value by afactor of over 3,000 by the end of the day,the radiation intensity will still be large,.

6.12 It has been calculated that if allthe fission products from an explosionwith a 1-megaton fission yield could bespread uniformly over a smooth area of10,000 square miles, the radiation expo-sure rate after 24 hours would be 6 roent-gens per hour at a level of 3 feet above theground. In actual practice, a uniform dis-tribution would be improbable, since a

large proportion of the fission productswould be deposited nearer ground zerothan at farther distances. Hence, the ra-diation intensity will greatly exceed theaverage at points near the explosion cen-ter, whereas at much greater distances itwill usually be less. The above exampledoes not include any neutron induced ac-tivity.

FORMATION OF FALLOUT

6.13 In a surface burst, large quan-tities of earth or water enter the fireballat an early stage and are fused or vapor-ized. When sufficient cooling has occurred,the fission products and other radioactiveresidues become incorporated with theearth particles as a result of the condensa-tion of vaporized fission products intofused particles of earth, etc. A small pro-portion of the solid particles formed uponfurther cooling are contaminated, fairlyuniformly throughout with radioactive fis-sion products and other weapon residues,but in the majority the contamination isfound mainly in a thin shell near the sur-face. In water droplets, the small fissionproduct particles occur at discrete pointswithin the drops. As the violent disturb-ance due to the explosion subsides, thecontaminated particles and droplets grad-ually fall back to earth. This effect is re-ferred to as the "fallout". It is the associ-ated radioactivity in the fallout, whichdecays over a long period of time, that isthe main source of residual nuclear radia:tions.

6.14 The extent and nature of the fal-lout can range between wide extremes.The actual behavior will be determined bya combination of circumstances associatedwith the energy yield and design of theweapon, the height of the explosion, thenature of the surface beneath the point ofburst, and the meteorological conditions,which we will discuss later. In the case ofan air burst, for example, occurring at anappreciable distance above the earth'ssurface, so that no surface materials aresucked into the cloud, negligible fallout isproduced. Thus at Hiroshima and Naga-saki, where approximately 20-kiloton de-vices were exploded 1,850 feet above the

surface, casualties due to fallout werecompletely absent.

6.15 On the other hand, a nuclear ex-plosion occurring at or near the earth's::,ttface can result in severe contaminationby the radioactive fallout. In the case ofthe 15-megaton thermonuclear devicetested at Bikini Atoll on March 1, 1954the BRAVO shot of Operation CASTLEthe ensuing fallout caused substantialcontamination over an area of more than7,000 square miles. The contaminated re-gion was roughly cigar-shaped and ex-tended more than 20 statute miles upwindand over 320 miles downwind. The widthin the crosswind direction was variable,the maximum being over 60 miles.

6.16 It should be understood that thefallout is a gradual phenomenon extend-ing over a period of time. In the BRAVOexplosion, for example, about 10 hourselapsed before the contaminated particlesbegan to fall at the extremities of the 7,000square mile area. By that time, the radio-active cloud had thinned out to such anextent that it was no longer visible. Thisbrings up the important fact that falloutcan occur even when the cloud cannot beseen. Nevertheless, the area of contamina-tion which presents the most serious haz-ard generally results from the fallout ofvisibl:-? particles.

6.17 The fallout pattern from particlesof visible size will have been establishedwithin about 24 hours after the burst. Thisis referred to as "early fallout" and is alsosometimes called "local" or "close-in" fal-lout. In addition, there is the deposition ofvery small particles which descend veryslowly over large areas of the earth's sur-face. This is the "delayed fallout," alsoreferred to as "worldwide fallout," towhich residues from nuclear explosions ofvarious typesair, high-altitude, surface,and shallow subsurfacemay contribute.

6.18 Although the test of March 1, 1954produced the most extensive local falloutyet recorded, it should be pointed out thatthe phenomenon was not necessarily char-acteristic of (nor restricted to) thermonu-clear explosions. It is very probable that ifthe same device had been detonated at anappreciable distance above the Coral Is-

83

land, so that the large fireball did nottouch the surface of the ground, the earlyfallout would have been of insignificantproportions.

WHAT GOVERNS THE LOCATION OFEARLY FAUOUT-

6,19 There are several .factors govern-ing the location of early fallout. These are:

1. Kind of weapon.2. Yield of the burst.3. Altitude of the burst.4. Height and dimension of the cloud.5. Distribution of radioactive particles

within the cloud.6. Radioactivity. associated with various

particle sizes.'7. Rate of fall of the particles.8. Meteorological conditions, including

wind structure to the top of the cloudand any type of precipitation.

6.20 These factors are so interrelatedthat it is almost impossible to isolate theeffects .of any one factor with precision.However, it is possible to discuss the gen-eral significance of each factor.

6.21 Kind of Weapon.Since the fusionproducts do not make a significant contri-bution of radioactive material to fallout,even when the weapon is a thermonuclearone (i.e., fusion is involved), only the fis-sion yield of a given weapon is importantin determining the total amount of raditiae-tive fallout. For example, although the to-tal amoTint of radioactive material pro-duced would be approximately the same ina 1 megaton 50%fission yield .weapon anda 2 megaton 25% fission yield weapon, theresulting fallout patterns would probablydiffer because of the greater height ob-tained by the 2 megaton cloud.

6.22 Altitude of the Burst (This is acrucial facto).The fraction of the totalradioactivity of the bomb residues thatappear in the early fallout depends uponthe extent that the -fireball touches thesurface. Thus, the proportion of the availa-ble activity contributing to early falloutincreases, as the height of burst decreasesand more of the fireball comes into contactwith the earth.84

6.23 Height and Dimension of theCloud.It is obvious that the physical sizeof the cloud at the time of stabilizationwill have an effect on the distribution ofearly fallout. The height to which the indi-vidual particles are carried principally de-termines how far downwind a given parti-cle size will drift, and the horizontal ex-tent of the cloud affects the width of thearea over which fallout will occur.

6.24 The eventual height reached bythe nuclear cloud depends upon the en-ergy of the bomb and upon the tempera-ture and density of the surrounding air.The greater the amount of energy liber-ated the greater will usually be the up-ward thrust due to buoyancy and so thegreater will be the distance the cloud as-cends. It is probable, however, that themaximum height obtainable by the nu-clear cloud is affected by the height of thetropopause, which is the boundary layerbetween the relatively stable air of thestratosphere and the more turbulent trop-osphere. (See Figure 6.24.)

STRATOSPHERETROPOPAUSE

TROPOSPHERE

/ x N%\.\

O°

FIGURE 6.24.The earth's atmosphere.

6.25 The height of the tropopause isusually slightly above 50,000 feet in thetropics and at 30,000 to 40,000 feet in mid-dle latitudes in the summer. In winter, inthe middle latitudes, it is somewhat loweron the average than in the summer. Forsmaller kiloton weapons the height of thetropopause generally limits the height ofthe nuclear cloud. Even for larger size

88

FEET130,000

110,000

90,000

70,000

50,000

30,000

10,000

0100 KT 1 MT 20 MT

FIGURE 6.25.Representative nuclear detonation cloud heights.

weapons in the megaton range, the devel-opment of the cloud slows down as thecloud builds up into the stratosphere.Thus the lower the tropopause, the lessthe total height of the cloud. Figure 6.25illustrates rough estimates of some possi-ble cloud heights under "typical" condi-tions.

6.26 Distribution of Radioactivitywithin the clouds.Figure 6.26 summa-rizes the distribution of radioactivitywithin the nuclear "cloud. You will notethat approximately 90% of the total activ-ity is located in the cloud and only 10% orless in the stem section with the bulk ofthe activity in the base of the cloud. It isfurther assumed that the bulk of the ra-dioactive material, that contributes toearly fallout will be at or below about80,000 feet. Above this altitude the parti-cles will probably be in a finely divk edstate and will contribute most to 1'

worldwide fallout.6.27 Amount of Radioactivity Associ-

ated with Various Particle Sizes.Fromexperimental evidence radioactive parti-cles are known to exist with diametersranging from .01 to 1,000 microns (A mi-

cron is 1 millionth of a meter). It is quitepossible that even smaller particles existsince the lower limit of this range is thelimit of the resolving power of the electronmicroscope. To determine the fallout pat-terns from a nuclear detonation it is nec-essary to know the distribution of the totalradioactivity among particles of various

8

FIGURE 6.26.Distribution of radioactivity.

85

sizes. Knowledge in this area is still ratherlimited because of the difficulty in obtain-ing: large and representative samples ofradioactive debris from a nuclear cloud.

6.28 Rate of Fall of Particles.The par-ticles carried up into the atmosphere by anuclear detonation are acted upon bygravity and carried by the winds. Since

86

wind directions and speeds usually varyfrom one level to another, each particlefollows a constantly changing course, andchanging speed as it falls to earth. Therate of fall depends upon the particle size,shape and weight and the characteristicsof the air. The stronger the wind in eachlayer the further the particles will be car-

EFFECT OF PARTICLE SIZE (WIND a INITIAL HEIGHT90,000 FT. ---00 ASSUMED CONSTANT)

60,000 FT. 40

30,000 FT. --O

GROUND

LARGE PARTICLESFALL FAST, LANDCLOSE

SMALL PARTICLESFALL SLOWLY,LAND FARTHERj

EFFECT OF HEIGHT (WIND a PARTICLE SIZE ASSUMED90,000 FT. --Oil. CONSTANT)

60,000 FT. ÷

30,000 FT. 00

GROUND

LOWER PARTICLESLAND SOONER,CLOSER

UPPER PARTICLESFALL LONGER,LARD FARTHER

EFFECT OF WIND (PARTICLE SIZE ASSUMED CONSTANT)90,000 FT.

STRONG60,000 FT. WIND

30,000 FT. III II \\PARTICLES0

, LAND CLOSEWEAKWIND

PARTICLES LAND FARTHER,MORE SPREAD OUT

GROUND ...ter 400EFFECT OF VARIABLE WIND (PARTICLE SIZE Bi INITIAL

90,000 FT. 4 HEIGHT ASSUMED CONSTANT)

60,000 FT.

30,000 FT. ---00

GROUND

PARTICLE'S MOVEMENT ISSUM OF ALL WIND FORCES

FIGURE 6.28.Factors affecting distribution of radioactive particles.

9 0

ried in that layer. The faster the particlefalls, the less influence the wind will haveon it and the closer to ground zero it willland. The higher the altitude at which itbegins to fall, the longer it will be carriedby the wind, and under most conditionswhen the winds at different altitudes donot oppose one anotherthe farther it willtravel. (See figure 6.28.)

6.29`. Conditions.Windsare the principal factor which affect themovement of the nuclear cloud. Even withthe same type, yield, and altitude of deto-nation, different wind conditions will pro-duce different fallout patterns of irregularshape. The speed and vertical shear of theupper air winds will also affect the concen-tration of radioactive material on theground. A fallout pattern under conditionsof strong winds aloft would differ fromthat of weak winds in two ways. First, thestrong wind would spread the materialover a larger area tending to reduce theconcentration close to the source. Second,at a given distance the fallout would ar-rive sooner and would have had less timeto decay.

6.30 The United States has a variety ofupper air winds. During the winter, spring,and fall seasons the United States windsare primarily the "prevailing westerlies."By this it is meant that the winds over theUnited States blow more frequently fromthe western quarter than from any otherquarters of the compass. The westerlies inthe middle latitudes become increasinglypredominant with increasing height up toabout 40,000 feet. At 5,000 feet the windsare from the western quadrant about halfthe time; while at 30-40,000 feet they arefrom that quadrant about three-fourths ofthe time. Above 40,000 feet, the percent-age of westerly winds again decreases.

6.31 The predominance of westerlywind direction changes with the seasons.Upper winds blow from the west moreoften during winter than during summer.The increase in frequency of other direc-tions in the summer is more pronounced inthe southeastern portion of the country,where directions become variable at alllevels. Along the Pacific Coast, the windsblow less constantly from the west than in

other sections of the country. Southwes-terly and northwesterly winds are morecommon. Above 60,000 feet, easterly windsoccur, frequently in all seasons and are therule in summer over most of the UnitedStates.

6.32 In describing direction of falloutfrom the point of detonation (GZgroundzero), the terms "upwind" and "down-wind" are often used. The "downwind"direction is the direction toward which thewind blows, while "upwind" means againstthe wind. When applied to fallout, theterms upwind and downwind will apply tothe resultant or total effect of all thewinds through which the particles havefallen. An upwind component results fromthe very rapid expansion of the cloud in alldirections immediately after detonation.The disturbances at the time of the explo-sion will deposit radioactive material inupwind and crosswind directions for rela-tively_short distances from ground zero.

6.33 Since the direction of fallout is de-termined by winds up to at least 80,000feet, and since winds in the upper airfrequently are quite different than windsat the surface, surface wind directionscannot be used as an indication of direc-tion of flow of high atmosphere winds. It isnot at all uncommon to have east, south,or north winds at the surface and westerlywinds aloft.

6.34 In considering the possible area offallout, wind speed is as important as winddirection. Depending on particle size, thedirection determines the sector to whichthey are carried; and the speed governshow far they will travel before coming tothe earth. Wind speeds over the UnitedStates generally are less in the summerthan in winter at all heights and above allsections of the United States. The onlyexceptions would be during the passage ofhurricanes or tornadoes which producevery strong surface winds in the warmseasons. This difference between seasonsis greatest in the southeastern portion ofthe country, where winds become particu-larly light and variable in the summer.During the winter, upper winds along thePacific Coast generally have lower speedthan in any other section of the United

9-i

87

States. Wind speeds increase with altitudefrom the surface up to a level between30,000 and 40,000 feet. Above this levelthey usually decrease in speed until at60,000 to 80,000 feet they become rela-tively light.

6.35 The winds of greatest speed us-ually occur between 30,000 and 40,000 feet,winds exceeding 50 m.p.h. being the ruleall over the country in winter and in thenortheast in the summer. In this layer,winds greater than 100 m.p.h. are at timese4perienced over all areas of the UnitedSates, but have been observed most oftenover the northeast, where they are foundabout 25% of the time. In this northeast-ern area, winds of 200 m.p.h. occur fre-quently, with speeds of 300 m.p.h. ob-served on rare occasions. The high speedwinds usually occur in narrow meanderingcurrents within the broad belt of middle-latitude westerly winds, and are called"jet-streams".

6.36 The strongest winds encounteredby a falling particle have the greatestproportional influence on its total move-ments. The strongest winds are usually ataltitudes in the vicinity of 40,000 feet.These winds would largely determine thegeneral direction and length of the falloutarea, although all the winds up to morethan twice that height could be effective,

6.37 Fallout patterns over the UnitedStates would probably differ in shape andextent. In the northern half of the countryconsiderably longer patterns would be ex-pected, spreading toward the east becauseof the strong upper air westerly winds.The passage of low pressure areas wouldcause shift" from a ?nore northeasterly toa more southeasterly spread of the falloutpattern from one day to another. In thesummer, particularly in the southern- partof the country, a great variety of patternsmight be expected with a broad irregularspreading in all directions in some cases,and elongated streaks in others. It shouldbe remembered also that in an area whereseveral target cities are situated within afew hundred miles of one another,, falloutfrom more than one detonation might occurat the same place.

88

6.38 Variation of the winds by day andnight has little effect on factors that de-termine fallout patterns. Winds a fewhundred feet aboveground frequentlychange from day to night, but those higherup, which have the greatest effect on thefallout pattern, do not follow a daily cycle.Cloudiness or fog alone are not believed tohave a marked effect on fallout, althoughthe combination of fallout particles withcloud droplets may result in_a faster rateof fall. Some cloud types also have upwardand downward air currents. The down-ward currents might tend to bring some ofthe radioactive debris down more rapidlythan it would otherwise settle.

6.39 In addition to the wind, precipita-tion in a fallout area will affect the radio-active deposition. Rain drops and snowflakes collect a large proportion of theatmospheric impurities in their paths.Particles of radioactve debris are"washed" or "scrubbed" out of the air byprecipitation. The result is that contami-nated material, which would be spreadover a much larger area by the slower dryweather fallout process, is rapidly broughtdown in local rain or snow areas. It isconceivable that hazardous conditions canoccur in rain areas where ordinary falloutestimates might indicate a safe condition.This scrubbing reduces the amount of con-tamination left in the air to fall out far-ther downwind.

6.40 Terrain features will also cause avariation in the-degree of deposition. Hills,valleys and slopes of a few hundred feetwould probably not have a great effect onthe fallout radiation levels. However,large mountains or ridges could cause sig-nificant variation in deposition by receiv-ing more fallout on the sides facing thesurface wind. This is true for both dryweather fallout and "rainout".

WORLDWIDE FALLOUT

6.41 Worldwide fallout by definition ismuch more widespread than early fallout.Worldwide fallout is that portion of thebomb residues which consists of very finematerial that remains suspended in theair for times ranging from days to years.

These fine particles can be carried overlarge areas by the wind and may ulti-mately be deposited on parts of the earthremote from the point of burst. It shouldnot be inferred from this term, however,that none of the fine, material is depositedin areas near the explosions nor that suchmaterial is deposited uniformly over theearth.

6.42 You will recall that early fallout isimportant only when the nuclear burstoccurs at or near the earth's surface sothat a large amount of debris is carried upinto the nuclear cloud. Contributions toworldwide fallout, however, can come fromnuclear explosions of all types, exceptthose so far beneath the surface that theball of fire does not break through andthere is, no nuclear cloud, or those deto-nated in outer space. With regard to themechanism of the worldwide fallout, a dis-tinction must be drawn between the be-havior of explosions of low energy yieldand those of high energy yield. If the burstoccurs in the lower part of the atmospherethe nuclear cloud from a detonation in thekiloton range will not generally rise abovethe top of the troposphere, consequently,nearly all the fine particles present in thebomb debris from such explosions will re-main in the troposphere until they areeventually deposited.

6.43 The fine fallout particles from thetroposphere are deposited in a complexway, complex, since various processes inaddition to simple, gravitational settlingare involved. The most important of theseprocesses appears to be the scavenging ef-feet of rain or other forms of moistureprecipitation. Almost all of the tropos-pheric fallout will be deposited within twoto three months 'after the detonation sothat bomb debris 'does not remain for verylong in the troposphere.

6.44 While the fine debris is suspendedin the troposphere the major part of thematerial is moved by the wind at highaltitudes. In general, the wind pattern issuch that the debris is carried rapidly inan easterly direction, making a completecircuit of the globe in some 4 to 6 weeks.Diffusion of the cloud to the north andsouth is relatively slow, with the result

that most of the fine tropospheric falloutis deposited in a short period of weeks in afairly narrow band and encircling theearth at the latitude of the nuclear deto-nation.

6.45 For explosions of high energy yieldin the megaton range nearly all the bombdebris will pass up through the tropo-sphere and enter the stratosphere. Thelarger particles will be deposited locallyfor a surface or sub-surface burst, whilethe very fine particles from bursts of alltypes can be assumed to be injected intothe stratosphere. Due to their finenessand the absence of clouds and rainfall atsuch high altitudes, the particles will set-tle earthward very slowly. Althoughagreement does not exist as to the mecha-nism that produces observed differences inworldwide fallout, it is now clear that non-uniform circulation of stratospheric debrisbetween the hemispheres is a characteris-tic of worldwide fallout. Also no agreementexists as to the residence time for world-wide fallout in the upper atmosphere, butit appears to be somewhere between 1 to 5years.

6.46 During its long residence in thestratosphere, the bomb residues diffuseslowly but widely, so that they enter thetroposphere at many points ove -r theearth's surface. Once in the troposphere,fine material behaves Eke that which re-mained initially in that part of the atmos-phere, and is brought to earth fairly rap-idly by rain or snow.

6.47 Anjmportant feature of the strat-ospheric worldwide fallout is the fact thatthe radioactive particles are, in effect, sto-red in the stratosphere with a small frac-tion continuously dribbling down to theearth's surface. While in stratosphericstorage, the debris does not represent adirect radioactive hazard. In fact, duringthis time most of the activity of the short-lived isotopes decays away and some of theactivity of the longer-lived isotopes is ap-preciably reduced. Thus, stratosphericworldwide fallout is a slow, continuousnon-uniform deposition of radioactive ma-terial over the entire surface of the earth,the rate_ of deposition depending on thetotal amount of bomb debris still present

89

in the stratosphere, the season of the yearand the amount of precipitation.

REPRESENTATION OF EARLY FALLOUTAREAS

-6.48 In a somewhat idealized situation,it is to be expected that, except for thevery smallest particles which descend overa wide area, the fallout of the larger parti-cles fall to earth forming a kind of elon-gated (or cigar shaped) pattern of contami-nation. The shape and dimensions will bedetermined by the wind velocities and di-rections at all altitudes between theground and the nuclear cloud. It should beemphasized that these elongated falloutpatterns are idealized, and an actual fal-lout pattern will not conform to these pat-terns.

6.49 At a particular time after the deto-nation of a nuclear weapon, the radiationexposure rate is apt to be highest atground zero, and will decrease as the dis-tance from ground zero increases. This isbecause the amount of fallout per unitarea is also likely to be less. There isanother factor that contributes to this de-crease in exposure rate with increasingdistances from the explosion. This factor istime. The later times of arrival of thefallout at these greater distances meanthat the fission products have decayed tosome extent while the particles were sus-pended in the air.

6.50 Some idea of the manner in whicha fallout pattern may develop over a largearea during the period of several hoursfollowing a high-yield nuclear surfaceburst may be seen in Figure 6.50. Forsimplicity of representation, the actualcomplex wind pattern is replaced by anapproximately equivalent or effectivewind of 15 miles per .hour. Figure 6.50shows a number of contours for certainarbitrary exposure rates that could possi-bly have been observed on the ground at 1,6 and 18 hours (H + H + 6; H + 18)respectively after the explosion. It shouldbe understood that the various exposurerates change gradually from one contourline to the next. Similarly, the last contourline shown does not represent the limit of

90

20 10 0 10 20 30 40 50 0 70 SO 90 100 110 120 130 140 50 140 170 ISO 110

1000300

10030

1000300

10030

6 HOUR300

1003A--10

18 HOUR

FIGURE 6.50.Contours from fallout at 1, 6, and 18hours after a surface burst with a fission yield inthe megaton range (15 m.p.h. effective wind). Val-ues given are in roentgens per hour.

contamination since the exposure rate willfall off steadily over a greater distance.

6.51 Consider first, a location 32 milesdownwind from ground zero.At one hourafter the detonation the observed expo-sure rate is seen to be about 30 R/hr; at 6hours the exposure rate which lies be-tween the contours for 1,000 and 300 R/hrhas increased to about 800 R/hr; but at 18hours it is down to roughly 200 R/hr. Theincrease in exposure rate from 1 to 6 hoursmeans the fallout was not complete onehour after detonation. The decrease from 6to 18 hours is then due to the naturaldecay of the fission products. On the otherhand a total radiation exposure receivedat the given location at one hour after theexplosion would be relatively small be-cause the fallout has only just started toarrive, By 6 hours the total exposure couldreach over 3,000 R and by 18 hours a totalexposure of some 5,000 R could have accu-mulated. Subsequently, the total exposurewould continue to increase but at a slowerrate.

6.52 Next, consider a point 100 milesdownwind from ground zero.At one hourafter the explosion the exposure rate, asindicated in Figure 6.50, is zero since thefallout will not have reached the specifiedlocation. At 6 hours the exposure rate is 10

9 4

R/hr and at 18 hours about 50. R/hr, Thetotal (infinite) exposure will not be asgreat, as at locations closer to ground zerobecause the quantity of fission productsreaching the ground decreases at increas-ing distances from the explosion.

UNCERTAINTIES IN FALLOUTPREDICTIONS

6.53 Idealized fallout patterns are use-ful for planning purposes, but they are notblueprints of the actual fallout patternthat would occur. There are just too manyuncertainties or variables involved in fal-lout, affecting both distribution of earlyfallout and rate of decrease of radioactiv-ity, to make precise prediction possible.

6.54 It is difficult to estimate the ex-tent of the induced radioactivity becauseof differences in type of weapon, theheight of burst, and the nature of the soilor other material in which neutron bom-bardment has caused radioactivity. Fur-thermore, the existence of unpredictablehot spots will affect local radiation expo-sure rates, as will the nature of the ter-rain (buildings, trees, etc., may reduce. theaverage radiation exposure rate above theground to 70 or 75 percent of the valuemeasured in open, flat terrain); weather-ing (wind may move surface-deposited fal-lout from one area to another or rain maywash it into the soil); fractionization (any

ARIZONA

N..AS VEGAS

FIGURE 6.54a.Fallout patterns from nuclear testdetonation at the Nevada Test Site.

9

FIGURE 6.54b.Fallout patterns from nuclear testdetonation at the Nevada Test Site.

FIGURE 6.54c.Fallout patterns tram nuclear testdetonation at the Nevada Test Site.

one of several processes, apart from radio-active decay, that results in change in thecomposition of the radioactive weapon de-bris); fission products of differing ages andother factors. These uncertainties or vari-ables mean that the cigar-shaped falloutpatterns are idealized, not necessarilyreal. To see how the idealized .pattern dif-fers from an actual pattern, refer to Fig-ures 6.54a through 6.54c which show fal-lout patterns from actual test detonationsat the Nevada Test Site. These patternswere developed from monitored readingstaken shortly after the test shots.

6.55 So far we have examined the fal-lout problem in general terms withouttrying to show the magnitude of the situa-

91

-------

tion that could exist if the entire nationshould be attacked. The map in Figure6.55a illustrates an assumed hypotheticalnuclear attack. Each circle represents a 20megaton surface explosion. There are 50 ofthese. Each square represents a 10 mega-ton surface,burst. There are 100 of these.Each triangle represents a 5 megatonburst and there are also 100 of these. Inthis hypothetical attack there are 250weapons dropped on 144 different targetswhich include military, industrial and pop-ulation objectives. The total yield of these250 weapons is equivalent to 2500 mega-tons or 2.5 billion tons of TNT!

6.56 Figure 6.55b shows the area thatwould be affected by fallout and the theo-retical levels of radiation one hour afterthe attack. The fallout areas would be 30to 50 miles long, depending upon windspeed and in the center of these areas thelevels of radiation could be greater than3,000 R/hr at H + 1.

6.57 Figure 6.55c illustrates the situa-tion 6 hours after attack. Fallout wouldhave spread over about 40% of the na-tional land area. However, the radiationlevels would have decayed by approxi-mately a factor of ten. The exposure ratesin these areas would range from one R/hralong the border to perhaps 400 R/hr inthe center. Figure 6.55d illustrates theareas that would be affected by fallout oneday after attack. Approximately 70% ofthe country's total area would be coveredby fallout exposure rates greater than 0.2R/hr. About 18% of the land area wouldhave a very serious fallout condition.

FIGURE 6.55a.Hypothetical attack pattern.

92

)

FIGURE 6.55b.Hypothetical attack, H +1 situation.Exposure rates exceed 10 R/hr.

-

FIGURE 6.55c.--Hypothetical attack, H +6 situation.Exposure rates exceed 1 R/hr.

FIGURE 6.55d.Hypothetical attack, H +24 sitaution.Exposure rates exceed .2 R/hr.

6.58 Shortly after the first day radioac-tive decay would bdgin to predominateover further deposition of fallout. Theboundaries of these fallout areas wouldgradually shrink.

Figure 6.55e illustrates the situation oneweek after attack during which time theradioactive areas would have been de-creasing in size and the exposure ratesdecreasing as a result of decay. Only aboutone-third of the nation's area would be

FIGURE 6.55e.Hypothetical attack, H +1 weeksituation. Exposure rates exceed .2 R/hr.

FIGURE 6.55f.Hypothetical attack, H +2 monthssituation. Exposure rates exceed .2 R/hr.

covered by fallout exposure rates exceed-ing 0.2 R/hr. This reduction in exposurerate would continue. Two months afterattack, the situation might exist as illus-trated in Figure 6.55f. We would find onlyisolated elongated islands where the levelsof radiation would exceed 0.2 R/hr.

6.59 It is emphasized that this trainingexercise represents just one attack pat-tern applied to the winds and weather ofone day. Had a different attack patternbeen selected or the weather for anotherday, the fallout situation would have de-veloped quite differently.

6.60 To illustrate the effects of differ-ent wind patterns on a hypothetical nu-clear attack, figure 6.60 shows a falloutprojection for a 156 weapon-384 megatonattack using the wind conditions that ex-isted on June 28, 1957.

6.61 Figure 6.61 shows the theoreticalfallout from the identical attack pattern

the same ground zeros and the sameweapon yieldsbut, based on the weatherof July 12, 1957. You will note that the axisof fallout deposition of many locations hasshifted by more than 120 degrees. On an-other day the wind could swing in anyother direction and turn safe areas onthese maps into areas of extreme falloutdanger.

FALLOUT FORECASTING

6.62 We have seen that one of the mostsignificant factors affecting the dispersionof fallout was the wind. We also saw thatdata can be obtained on wind directionand speed at various altitudes. Since amajor influence on fallout is one aboutwhich considerable data are known, it ena-bles us to predict with some degree ,ofaccuracy the probable pattern of falloutdispersion. The requirements of fallout

FIGURE 6.60.Hypothetical attack, fallout patternfor winds of June 28, 1957.

FIGURE 6.61.Hypothetical attack, fallout patternfor winds of July 12, 1957.

93

prediction from wind direction and speedare two: accurate data and current data.Both of these conditions are met by thenetwork of rawin observatories estab-lished by the United States and CanadianWeather Services.

6.63 The purpose of preparing falloutforecast plots is to provide graphic esti-mates of areas that are likely to receivefallout and the approximate time of falloutarrival. Figure 6.63 illustrate, falloutforecast plot. The area inside the heavy"U" shaped pattern and the dashed three-hour line represents land which could becovered with fallout within three hours ofa nuclear surface detonation upon the cityof Roanoke. The dished one-hour and two-hour lines represent fallout arrival timesand provide for forecasting fallout arrivalat various places within the forecast plot.

For example, at Lynchburg, fallout wouldbe forecast to arrive about one hour afterdetonation.

Information provided by the forecasts islimited to areas that may be covered byfallout and the approximate times of fal-lout arrival within the forecast area. Pre-dicted radiation levels or exposure ratesare not included in the forecasts.

6.64 Meteorological data for the con-struction of fallout forecast plots are avail-able to all levels of government in theform of "DE' messages which are trans-mitted by teletype over the nationalweather service network. Data points areshown on Figure 6.64. Arrangements forthe receipt of LF messages should bemade to support operations in the event ofa fallout emergency.

6.65 The Defense Civil Preparedness

FIGURE 6.63.A fallout forecast plot.

94

;:2

SEA

Tai

LKV

Pz7.-

SF0

FAT

RV112

CRWO663

I79091.,.652

CTFGG1N 14'

GEC/ 4 FCA GFK

BIL

JO AN

c01

QT

SSM

Ye731

r"7,\c A

5?!.

AUGPLe.,;,,,-

IBOS

PIN

I I ?KS__RNO

ELI I SLC icOLOi

TPH ii con

BCE

\ LAS0:G ,\1-: I FMN

1 ABCSAN (YUM

CPR

ALS

OT7

ALASKA m(c)0

BET

SNPSYA

r.,7AOK

TUs

814191871

877Al

ORT

JNU

Oe

YAKMOOANCNHB

ANN

OEN

1".4" -91 HLC .MKC

ICT STL

at I, 1".SGF

-,ZAn OK . ..""'"C \ LIT iP!ma

I

LPH0.81

DAll AL

'sty

ORT SAT

LIH

Au

U

CRP

LRO

' p ITO

OHAWAII

13 14 0

5260

PUERTO RICO

FIGURE 6.64.--DF data points.

Agency has prepared a manual of detailedinstructions on the construction and use offallout forecasts. This manual is entitled"Users ManualMeteorological Data forRadiological Defense," (FG-E-5.6/1). Themanual explains the "DF" message for-mat, gives instructions on preparing fal-lout forecast areas, and illustrates how toestimate fallout arrival time for opera-tional use. The manual may be obtainedthrough regular civil preparedness chan-nels.

ILM

MIA

HAT

SJ609

REFERENCES

The Effects of Nuclear Weapons.Glas-stone, Samuel, 1964.

Fallout From Nuclear Tests.Hearingsbefore the Special Subcommittee on Ra-diation of the Joint Committee on AtomicEnergy, Congress of the United States,May 1959.

Users ManualMeteorological Data forRadiological Defense.FG-E-5.6/1, July1970.

9 995

EFFECTS OF NUCLEAR RADIATION EXPOSURE

We have learned that nuclear radiationis a form of energy which has the power todamage living cells or tissue. In this chap-ter, our objective is to explain:

WHAT argethe effects of nuclear radia-tion

HOW are they producedWe are going to take a look into a human

cell and see what happens when it is sub-jected to nuclear radiation, what kind ofdamage is produced and the effects of thisdamage. And there is something else wewill learn, too, something that is VITAL ineffective RADEF work:

WHAT is the tolerance of the humanbody to nuclear radiationhowmuch can we standhow longcan we stand it

INTRODUCTION

7.1 Late one November afternoon in1895, as the German physicist WilhelmRoentgen was sending an electric currentat high voltage through a vacuum tube, henoticed a weak light that shimmered on alittle bench he knew was located nearby.It seemed as if the spark of light inside thetube was being reflected in a mirror. Strik-ing a match, he saw that a screen withsome barium salt crystals on the benchwas shining with fluorescent brilliance.Later, he held a piece of paper, then aplaying card, and then a book bet Ikeen thetube and the screen. He was amazed to seethat, even with the book plced in front ofthe tube, THE CRYSTALS STILL BE-CAME FLUORESCENT. Despite everylaw of science (as then understood) he hadto admit it: SOMETHING, some unknownor "X" quantity, was passing right throughthe solid book. He then tried to see if other

100

CHAPTER 7

materials would stop the "something".Eventually, he tried placing a thin sheetof lead between the tube and the crystalsand found that it did stop the passage ofthat something. Trying further experi-ments, he picked up a small lead piece andheld it up before the tube. He was stag-gered to see that not only did the rounddark shadow of the disk appear on thescreen of barium crystals, BUT THAT HECOULD DISTINGUISH THE OUTLINEOF HIS THUMB AND FINGERS. Notonly that, but within this outline weredarker shadows: THE BONES OF HISHAND. These phenomena were so con-trary to common sense, that Roentgenworked in secrecy, afraid that he might bediscredited for such "unscientific" work.Even his best friends were kept in thedark. When one insisted on knowing whatwas going on, Roentgen said, "I have dis-covered something interesting, but I donot know whether or not my observationsare correct."

7.2 Finally, after continued experi-ments including the first X-ray photo-graph (taken of his wife's hand), Roentgenrealized that he must tell the world of hisfindings. He reported all his experiments,stating that the phenomena were causedby some form of invisible radiant energy.He called this energy "X-rays", the "X"standing for unknown.

7.3 The story broke in the ViennaPresse on January 5, 1896, and soon scien-tists all over the world, including ThomasEdison, were excitedly experimenting withthis new kind of ray. The boon to medicineof X-rays, or Roentgen-rays as they werelater called, was obvious: examining bro-ken bones and fractures; locating tumorsor other abnormalities. For some,were even a source of amusement, a hobby

97

or playtoy. In 1896, the following adver-tisement appeared in the magazine Scien-tific American:

"Portable X-ray apparatus for physi-cians, professors, photographers andstudents, complete in handsome case,including coil, condenser, two sets oftubes, battery, etc., for the price of$15.00 net, delivered in the UnitedStates with full guarantee."7.4 Not understanding the nature of X-

rays, those early users of this new form ofenergy did not treat it with respect. It waseven customary to use the hand as a fluo-roscopic test object in controlling the qual-ity of the roentgen or X-rays. Soon, thosewho were exposed to continual large dosesof X-rays, patients, doctors, students, sci-entists alike, began to notice painful ef-fects. One, Dr. Emil H. Grubbe of Chicago,said: "I had developed dermatitis on theback of my left hand which was so acutethat I sought medical aid." The "dermati-tis" was a radiation burn, and Dr.Grubbe's fingers and hands had been sobadly burned by the X-rays that subse-qUently they were amputated piecemealas the damaging effects of overexposurespread.

7.5 Since it was noticed that exposureto X-rays caused the hair to fall out, someconcluded that X-rays were a good way toremove excess hair. One example, cited byDr. W. E. Chamberlain of Temple Univer-sity, shows what could happen:

A doctor in a small town heard that X-rays make hair fall out. His comely littlesecretary complained of having hairyarms. Apparently unaware of the poten-tialities for harm, the doctor adminis-tered X-rays with his portable radi-ographic machine. Horrible X-ray burnsdeveloped, and in due time the younglady's arms had to be amputated.7.6 By 1922 it was estimated that 100

radiologists had perished from overexpo-sure to radiation. Continued experimentsclearly showed that all living tissue couldbe destroyed provided it was bombardedwith a sufficiently high dosage of radia-tion.

7.7 A few months after Roentgen dis-covered X-rays, the French scientist HenriBecquerel found that certain uranium98

101

salts gave off penetrating rays, similar inoperation to X-rays. Later, Pierre Curieand his wife, Marie, tried to find the sub-stance responsible for the radiation thatBecquerel had observed. It was MarieCurie who termed this activity RADIOAC-TIVITY, to which you were introduced inChapter 2. After intensive work, the Cur-ies found two new radioactive elements,"polonium" and "radium". From repeatedoverexposures in her work with radioac-tive substance'S;--Madam curie suffered ra-diation injury and subsequently died fromthe delayed effects of radium damage. Herdaughter, Irene Curie, carried on themother's work, and she too died from over-exposure to radiation.

7.8 What happens when living tissue isbombarded with radiation? Why does itcause so much havoc to the body? These,and other questions will be ansWered insubsequent paragraphs.

NUCLEAR RADIATION INJURIES

7.9 Each advance in man's power overnature has brought with it an element ofdanger. X-ray and nuclear radiation is noexception. We adopt a policy of acceptablerisk in every facet of our lives. Societymust decide what risk it will accept in theuse of nuclear radiation. The scientistmust clearly set forth the hazards.

The primary biological effect of nuclearradiation on life is in the cell. The normallife process in a cell uses a very smallamount of energy with a high degree ofself-regulation. When ionizing radiationstrikes a cell it disrupts the living process.The specialized parts of a cell, such as thegenes, are damaged not only by direct hitsbut also by the chemical poisons producedby ionization of the cell fluid. Many yearsago radiologists noted that the number ofcells damaged by a given exposure to ra-diation is a simple function of the numberof living cells present. In other words, thenumber of cells damaged per unit of doseis constant. The number of cells in whichgenetic damage occurs is also a function ofdose.

7.10 A higher plant or animal such asman consists of many cells. Higher forms

of life are a society of specialized andinterdependent cells. Radiation damage toone organ or group of specialized cells candisturb other organs and weaken thewhole organism. Man's life functions arecarried out within a very narrow range oftemperature, air, nutrients, water and ra-diation. This cooperative action of cellsand tissues makes higher forms of lifemuch more vulnerable to radiation thanlower forms of life. Furthermore, individu-als of the same species react differently toa radiation dose just as people react differ-

,ently to a cold.

RADIATION UNITS

7.11 The radiation unit is known as theroentgen. By definition, it is applicableonly to gamma rays or X-rays and not toother types of ionizing radiation, such asalpha and beta particles and neutrons.Since the roentgen refers to a specificresult in air accompanying the passage ofan amount of radiation through air, it doesnot imply any effect which it would pro-duce in a biological system. Because ofthis, the roentgen is, strictly speaking, ameasure of radiation "exposure." The ef-fect on a biological system, however, isexpressed in terms of an "absorbed dose."By comparing the actual biological effectsof different types of ionizing radiation, itis possible to convert the absorbed doseinto a "biologically significant dose" whichprovides an index of the biological injurythat might be expected.

7.12 The absorbed dose of radiationwas originally expressed in terms of a unitcalled the "rep," the name being derivedfrom the initial letters of "roentgen equiv-alent physical." It was used to denote adose of about 97 ergs of any nuclear radia-tion absorbed per gram of body tissue;however, for various reasons this unit hasproved to be somewhat unsatisfactory. Inorder to avoid difficulties arising in theuse of the rep, a new unit of radiationabsorption, called the "rad," has come intogeneral use. The rad is defined as theabsorbed dose of any nuclear radiationwhich is accompanied by the liberation of100 ergs of energy per gram of absorbing

102

material. For soft tissue, the differencebetween the rep and the rad is small, andnumerical valu"Q of absorbed dose for-merly expressed in reps are essentiallyunchanged when converted to rads.

7.13 Although all ionizing radiationsare capable of producing similar biologicaleffects, the absorbed dose (measured inrads) which will produce a certain effectmay vary appreciably from one type ofradiation to another. This difference inbehavior is expressed by means of the"relative biological effectiveness" (orRBE) of the particular nuclear radiation.The RBE of a given radiation is defined asthe ratio of the absorbed dose in rads ofgamma radiation (of a specified energy)2 tothe absorbed dose in rads of the givenradiation having the same biological ef-fect.

7.14 The value of the RBE for a partic-ular type of nuclear radiation dependsupon several factors, including the doserate, the energy of the radiation, the kindand degree of the biological damage, andthe nature of the organism or tissue underconsideration. As far as nuclear weaponsare concerned, the important criteria aredisabling sickness and death.

7.15 With the concept of the RBE inmind, it is now useful to introduce anotherunit, known as the "rem," an abbreviationof "roentgen equivalent mammal (orman)." The rad is a convenient unit forexpressing energy absorption, but it doesnot take into account the biological effectof the particular nuclear radiation ab-sorbed. The rem, however, which is de-fined by: dose in rems = RBE X dose inrads, provides an indication of the extentof biological injury (of a given type) thatwould result from the absorption of nu-clear radiation. Thus, the rem is a doseunit of biological effect, whereas the rad isa unit of absorbed energy dose and theroentgen (for X or gamma rays) is one ofexposure.

3 Because 1 roentgen exposure gives about 1 rad absorbed dose intissue for photons of intermediate energies (0.3 to 3 MeV), the absorbeddose for gamma (or X) rays is often stated, somewhat loosely, in"roentgens." However, for photon energies outside the range from 0.3to 3 MeV, the exposure in roentgens is no longer simply related to theabsorbed dose in rads.

99

7.16 All radiation capable of prodUcingionization (or excitation) directly or indi-rectly, e.g., alpha and beta particles, X-rays, gamma rays, and neutrons, causeradiation injury of the same general type.However, although the effects are qualita-tively similar, the various-radiations differin the depth to which they penetrate thebody and in the degree of injury corre-sponding to a specified amount of energyabsorption. As seen above,- the latter dif-ference is expressed by means of the RBE.

7.17 The RBE for gamma rays is ap-proximately unity. For beta particles, theRBE is also close to unity; this means thatfor a given amount of energy absorbed inliving tissue, beta particles produce aboutthe same extent of injury within the bodyas do X-rays or gamma rays. The RBE foralpha particles from radioactive sourceshave been variously reported to be from 10to 20, but this is believed to be too large inmost cases of interest. For nuclear weaponneutrons, the RBE for acute radiation in-jury is now taken as 1.0, but it is apprecia-bly larger where the formation of opacitiesof the lens of the eye (cataracts) is con-cerned. In other words, neutrons are muchmore effective than gamma rays in caus-ing cataracts.

7.18 In considering the possible effectson the body of gamma radiations fromexternal sources, it is necessary to distin-guish between an "acute" (or "one-shot")exposure and a "chronic" (or extended)exposure. In an acute exposure the wholeradiation dose is received in a relativelyshort interval of time. This is the case,.forexample, in connection with the initial nu-clear radiation. It is not possible to definean acute dose precisely, but it may besomewhat arbitrarily taken to be the dosereceived during a 24-hour period. Al-though the delayed radiations from earlyfallout persist for longer times, it is duringthe first day that the main exposure wouldbe received and so it is regarded as beingacute. On the other hand, an individualentering a fallout area after the first dayor so and remaining for some time wouldbe considered to have been subjected to achronic exposure.

100

7.19 The importance of making a dis-tinction between acute and chronic expo-sures lies in the fact that, if the dose rateis not too large, the body can achievepartial recovery from some of the conse-quences of nuclear radiations while stillexposed. Thus, apart from certain effectsmentioned later, a larger total gamma-radiation dose would be required to pro-duce a certain degree of injury if the dosewere spread over a period of several weeksthan if the same dose were received withina minute or so.

7.20 All living creatures are always ex-posed to ionizing radiations from variousnatural sources, both inside and outsidethe body. These are chronic exposures con-tinuing for a lifetime. The chief internalsource is the radioisotope potassium-40,which is a normal constituent of the ele-ment potassium as it exists in nature.Carbon-14 in the body is also radioactive,but it is only a minor source of internalradiation. Some potassium-40, as well asradioactive uranium, thorium, and radiumin varying amounts, is also present in soiland rocks. The so-called "cosmic rays,"originating in space, are another impor-tant source of ionizing radiations in na-ture. The radiation dose received fromthese rays increases with altitude up toabout 90,000 feet; at 15,000 feet, it is morethan five times as great as at sea level.The high radiation levels encountered inthe Van Allen belts at much higher alti-tudes do not contribute to the backgroundradiation on earth.

GENERAL RADIATION EFFECTS

7.21 The effect of nuclear radiations onliving organisms depends not only on thetotal dose, that is, on the amount ab-sorbed, but also on the rate of absorption,i.e., on whether it is acute or chronic, andon the region and extent of the body ex-posed. A few radiation phenomena, suchas genetic effects, apparently depend pri-marily upon the total dose received and toa lesser extent on the rate of delivery. Theinjury caused by radiation to the germcells under certain conditions appears tobe cumulative. In the majority of in-stances, however, the biological effect of a

10_3

given total dose of radiation decreases asthe rate of exposure decreases. Thus, tocit"e"an extretrie case, 1,000 rems in a singledOSe would be fatal if the whole body wereexposed, but it would probably not haveany noticeable external effects in the ma-jority of persons if delivered more or lessevenly over a period of 30 years.

7.22 The injury caused by a certaindose of radiation will depend upon theextent and part of the body that is ex-posed. One reason for this is that when theexposure is restricted, the unexposed re-gions can contribute to the recovery of theinjured area. But if the whole body isexposed, many organs are affected andrecovery is much more difficult.

7.23 Different portions of the bodyshow different sensitivities to ionizing ra-diations, and there are variations in de-gree of sensitivity among individuals. Ingeneral; the most radiosensitive parts in-clude the lymphoid tissue, bone marrow,spleen, organs of reproduction, and gas-trointestinal tract. Of intermediate sensi-tivity are the skin, lungs, and liver,whereas muscle, nerves, and adult bonesare the least sensitive.

EFFECTS OF ACUTE RADIATION DOSES

7.24 Before the nuclear bombings of Hi-roshima and Nagasaki, radiation injurywas a rare occurrence and relatively littlewas known of the phenomena associatedwith whole-body exposure and radiationinjury. In Japan, however, a large numberof individuals were exposed to doses ofradiation ranging from insignificant quan-tities to amounts which proved fatal. Theeffects were often complicated by otherinjuries and shock, so that the symptomsof radiation sickness could not always beisolated. Because of the great number ofpatients and the lack of facilities after theexplosions, it was impossible to make de-tailed observations and keep accurate rec-ords. Nevertheless, certain important con-clusions have been drawn from Japaneseexperience with regard to the effects ofnuclear radiation on the human organism.

7.25 Since 1945, further information onthis subject has been gathered from other

104

sources. These include a few laboratoryaccidents involving a small number of hu-man beings, whole-body irradiation used intreating various diseases and malignan-cies, and extrapolation to man of observa-tions on animals. In addition, detailedknowledge has been obtained from a care-ful study of over 250 persons in the Mar-shall Islands, who were accidentally ex-posed to nuclear radiation from falloutfollowing the test explosion on March 1,1954. The exposed individuals includedboth Marshallese and a small group ofAmerican servicemen. The whole-body ra-diation doses ranged from relatively smallvalues (14 rems), which produce noobvious symptoms, to amounts (175 rems)which caused marked changes in theblood-forming system.

7.26 No single source of data directlyyields the relationship between the physi-cal dose of ionizing radiation and the clini-cal effect in man. Hence, there is no com-plete agreement concerning the effect as-sociated with a specific dose or dose range.Attempts in the past have been made torelate particular symptoms to certain nar-row ranges of exposure; however, the dataare incomplete and associated with manycomplicating factors that makeinterpretation difficult. For instance, theobservations in Japan were very sketchyuntil 2 weeks following the exposures, andthe people at that time were sufferingfrom malnutrition and preexisting bacte-rial and parasitic infections. Conse-quently, their sickness was often erro-neously attributed to the effects of ioniz-ing radiation when such was not necessar-ily the case. The existing conditions mayhave been aggravated by the radiation,but to what extent it is impossible to esti-mate in retrospect.

7.27 In attempting to relate the radia-tion dose to the effect on man, it should bementioned that reliable information hasbeen obtained for doses up to 200 rems. Asthe dose increases from 200 to 600 remsthe data from expoied humans decreaserapidly and must be supplemented moreand more by extrapolations based on ani-mal studies. Nevertheless, the conclusionsdrawn can be accepted with a reasonable

101

0

RA

NG

E0

TO

100

RE

MS

SU

BC

LIN

ICA

LR

AN

GE

100

TO

1,0

00 R

EM

S T

HE

RA

PE

UT

IC R

AN

GE

OV

ER

1,0

00 R

EM

S L

ET

HA

L R

AN

GE

" 10

0 T

O 2

00 R

EM

S20

0 T

O 6

00 R

EM

S60

0 T

O 1

,000

FIE

MS

_.1,

000

TO

5,0

00 R

EM

SO

VE

R 5

,000

RE

MS

CLI

NIC

AL

SU

RV

EIL

LAN

CE

TH

ER

AP

Y E

FF

EC

TIV

ET

HE

RA

PY

PR

OM

ISIN

GT

HE

RA

PY

PA

LLIA

TIV

E

INC

IDE

NC

E O

FV

OM

ITIN

GN

ON

E

.--.

0

100

RE

MS

5%

200

RE

MS

50%

300

RE

MS

100

%10

0%10

0%

DE

LAY

TIM

E-

3 H

OU

RS

2 H

OU

RS

I HO

UR

30 M

INU

TE

S

LEA

DIN

G O

RG

AN

NO

NE

HE

MA

TO

PO

IET

IC T

ISS

UE

GA

ST

RO

INT

ES

TIN

AL

TR

AC

TC

EN

TR

AL

NE

RV

OU

SS

YS

TE

M

CH

AR

AC

TE

RIS

TIC

SIG

NS

NO

NE

MO

DE

RA

TE

LEU

KO

PE

NIA

SE

VE

RE

LE

UK

OP

EN

IA; P

UR

PU

RA

; HE

MO

R-

RH

AG

E; I

NF

EC

TIO

N.

EP

ILA

TIO

N A

BO

VE

300

RE

MS

DIA

RR

HE

A; F

EV

ER

DIS

TU

RB

AN

CE

OF

ELE

CT

RO

LYT

E.

BA

LAN

CE

.

CO

NV

ULS

ION

S;

TR

EM

OR

; AT

I.XIA

;LE

TH

AR

GY

.

CR

ITIC

AL

PE

RIO

DP

OS

T -

EX

PO

SU

RE

--

4 T

O 6

WE

EK

S5

TO

14

DA

YS

I TO

48

HO

UR

S

TH

ER

AP

YR

EA

SS

UR

AN

CE

RE

AS

SU

RA

NC

E;

HE

MA

TO

LOG

ICS

UR

VE

ILLA

NC

E.

BLO

OD

TR

AN

SF

US

ION

;A

NT

IBIO

TIC

S.

CO

NS

IDE

R B

ON

EM

AR

RO

W T

RA

NS

-P

LAN

TA

TIO

N.

MA

INT

EN

AN

CE

OF

ELE

CT

RO

LYT

EB

ALA

NC

E.

SE

DA

TIV

ES

PR

OG

NO

SIS

EX

CE

LLE

NT

EX

CE

LLE

NT

GO

OD

GU

AR

DE

DH

OP

ELE

SS

CO

NV

ALE

SC

EN

T P

ER

IOD

INC

IDE

NC

E O

F D

EA

TH

NO

NE

NO

NE

SE

VE

RA

L W

EE

KS

NO

NE

I TO

12

MO

NT

HS

OT

O 8

0% (

vor.

)LO

NG

80%

T0

100%

(vo

t.)90

TO

100

%

DE

AT

H O

CC

UR

S W

ITH

IN-

-2

MO

NT

HS

2 W

EE

KS

2 D

AY

S

CA

US

E O

F D

EA

TH

--

HE

MO

RR

HA

GE

; IN

FE

CT

ION

CIR

CU

LAT

OR

YC

OLL

AP

SE

RE

SP

IRA

TO

RY

FA

ILU

RE

;B

RA

IN E

DE

MA

.

PA

LLIA

TIV

E -

AF

FO

RD

ING

RE

LIE

F, B

UT

NO

T A

CU

RE

.H

EM

AT

OP

OIE

T1C

TIS

SU

E-B

LOO

D F

OR

MIN

G T

ISS

UE

.LE

UK

OP

EN

IA-R

ED

UC

TIO

N IN

NU

MB

ER

OF

WH

ITE

BLO

OD

CE

LLS

(le

ukoc

ytes

)

PU

RP

UR

A-L

IVID

SP

OT

S O

N T

HE

SK

IN O

R M

UC

OU

S M

EM

BR

AN

ES

ED

EM

A-A

BN

OR

MA

L A

CC

UM

ULA

TIO

N O

F F

LUID

S IN

TH

E T

ISS

UE

FIG

UR

E 7

.28.

Sum

mar

y of

eff

ects

fro

m b

rief

nuc

lear

rad

iatio

nex

posu

re.

degree of confidence. Beyond 600 rems,however, observations on man are so spo-radic that the relationship between doseand biological effect must be inferred orconjectured almost entirely from observa-tions made on animals exposed to ionizingradiations.

7.28 With the foregoing facts in mind,Figure 7.28 is presented as the best availa-ble summary of the effects of variouswhole-body dose ranges of ionizing radia-tion on human beings. Below 100 rems, theresponse is almost completely subclinical;that is to say, there is no sickness requir-ing special attention. Changes may, never-theless, be occurring in the blood, as willbe seen later. Between 100 and 1,000 remsis the range in which therapy, i.e., propermedical treatment, will be successful atthe lower end and may be successful at theupper end. The earliest symptoms of radia-tion injury are nausea and vomiting,which may commence within about 1 to 3hours of exposure, accompanied by discom-fort (malaise), loss of appetite, and fatigue.The most significant, although not imme-diately obvious, effect in the range underconsideration, is that on the hematopoietictissue, i.e., the organs concerned with theformation of blood. An important manifes-tation of the changes in the functioning ofthese organs is leukopenia, that is, a de-cline in the number of leukocytes (whiteblood cells). Loss of hair (epilation) will beapparent about 2 weeks or so after receiptof a dose exceeding 300 rems.

7.29 Because of the increase in the se-verity of the radiation injury and the vari-ability in response to treatment in therange from 100 to 1,000 rems, it is conven-ient to subdivide it into three sub-sections,as shown in Figure 7.28. For whole-bodyexposures from 100 to 200 rems, hospitali-zation is generally not required, but above200 rems admission to a hospital is neces-sary so that the patient may receive suchtreatment as may be indicated. Up to 600rems, there is reasonable confidence in theclinical events and appropriate therapy,but for doses in excess of this amountthere is considerable uncertainty and vari-ability in response.

7.30 Beyond 1,000 rems, the prospects

of recovery are so poor that therapy may.be restricted largely to palliative meas-ures. It is of interest, however, to subdi-vide this lethal range into two parts inwhich the characteristic clinical effectsare different. Although the dividing linehas been somewhat arbitrarily set at 5 000rems in Figure 7.28, human data are solimited that this dose level might wellhave any value from 2;000 to 6,000 rems.In the range from 1,000 to (roughly) 5,000rems, the pathological changes are mostmarked in the gastrointestinal tract,whereas in the range above 5,000 rems, itis the central nervous system which ex-hibits the major injury.

7.31 The superposition of radiation ef-fects upon injuriels from other causes maybe expected to result in an increase in thenumber of cases of shock. For example, thecombination of sublethal nuclear radiationexposure and moderate thermal burns willproduce earlier and more severe shockthan would the comparable burns alone.The healing of wounds of all kinds will beretarded because of the susceptibility tosecondary infection accompanying radia-tion injury and for other reasons. In fact,infections, which could normally be dealtwith by the body, may prove fatal in suchcases.

CHARACTERISTICS OF ACUTE WHOLE-BODY RADIATION INJURY

7.32 Single doses in the range of from25 to 100 rems over the whole body willproduce nothing other than blood changes.These changes do not usually occur belowthis range and are not produced consist-ently at doses below 50 rems. Disablingsickness does not occur and exposed indi-viduals should be able to proceed withtheir usual duties. Thus, for

doses of 25 to 100 rems :no illness7.33 Exposure of the whole body to a

radiation dose in the range of 100 to 200rems will result in a certain amount ofillness but it will rarely be fatal. Doses ofthis magnitude were common in Hiro-shima and Nagasaki, particularly amongpersons who were at some distance fromthe nuclear explosion. Of the 267 individu-

103103

als accidentally exposed to fallout in theMarshall Islands following the test explo-sion of March 1, 1954, a group of 64 re-ceived radiation doses in this range. Itshould be pointed out that the exposure ofthe Marshallese was not strictly of theacute type, since it extended over a periodof some 45 hours. More than half the dose,however, was received within 24 hours andthe observed effects were similar to thoseto be expected from an acute exposure ofthe same amount. Thus, for

doses of 100 to 200 reins : slight or noillness

7.34 The illness from radiation doses inthis range does not present a serious prob-lem in that most patients will suffer littlemore than disconifort and fatigue and oth-ers may have no symptoms at all. Theremay be some nausea and vomiting on thefirst day or so following irradiation, butsubsequently there is a so-called "latentperiod," up to 2 weeks or more, duringwhich the patient has no disabling illnessand can proceed with his regular occupa-tion. The usual symptoms, such as loss ofappetite and malaise, may reappear, but ifthey do, they are mild. The changes in thecharacter of the blood, which accompanyradiation injury, become significant dur-ing the latent period and persist for sometime. If there are no complications, due toother injuries or to infection, there will berecovery in essentially all cases. In gen-eral, the more severe the early stages ofthe radiation sickness, the longer will bethe process of recovery. Adequate careand the use of antibiotics, as may be indi-cated clinically, can greatly expedite com-

,plete recovery of the small proportion ofmore serious cases.

7.35 For doses between 200 and 1,000rems the probability of survival is good atthe lower end of the range but poor at theupper end. The initial symptoms are simi-lar to those common in radiation injury,namely, nausea, vomiting, diarrhea, loss ofappetite, and malaise. The larger the dose,the sooner will these symptoms develop,generally during the initial day of theexposure. After the first day or two thesymptoms disappear and there may be alatent period of several days to 2 weeks104

during which the patient feels relativelywell, although important changes are oc-curring in the blood. Subsequently, thereis a return of symptoms, including fever,diarrhea, and a step-like aise in tempera-ture which may be due to accompanyinginfection. Thus, for

doses of 200 to 1,000 rems : survivalpossible

7.36 Commencing about 2 or 3 weeksafter exposure, there is a tendency tobleed into variouF organs, and small hem-orrhages under the skin (petechiae) areobserved. This tendency may be marked.Particularly common are spontaneousbleeding in the mouth and from the liningof the intestinal tract. There may be bloodin the urine due to bleeding in the kidney.The hemorrhagic tendency dependsmainly upon depletion of the platelets inthe blood, resulting in defects in the blood-clotting mechanism. Loss of hair, which isa prominent consequence of radiation ex-posure, also starts after about 2 weeks,immediately following the latest period,for doses over 300 rems. (See Figure 7.36.)

II 0

FIGURE 7.36.Epilation due to radiation exposure.

j 7.37 Susceptibility to infection ofwounds, burns, and other lesions, can be aserious complicating factor. This would re-sult to a large degree from loss of thewhite blood cells, and a marked depressionin the body's immunological process. Forexample, ulceration about the lips maycommence after the latent period andspread from the mouth through the entiregastroinestinal tract in the terminal stageof\ the sickness. The multiplication of bac-teria, made possible by the decrease in thewhite cells of the blood and injury to otherimmune mechanisms of the body, allowsan overwhelming infection to develop.

7.38 Among other effects observed inJapan was a tenden-cy toward spontaneousinternal bleeding near the end of the firstweek. At the same time, swelling and in-flammation of the throat was not uncom-mon. The development of severe radiationillness among the Japanese was accom-panied by an increase in the body temper-ature, which was probably due to second-ary infection. Generally there was a step-like rise between the fifth and seventhdays, sometimes as early as the third dayfollowing exposure,. and usually continu-ing until the day of death.

7.39 In addition to fever, the more seri-ous cases exhibited severe emaciation anddelirium, and death occurred within 2 to 8weeks. Examination after death revealeda decrease in size of and degenerativechanges in testes and ovaries. Ulcerationof the mucous membrane of the large in-testine, which is generally indicative ofdoses of 1,000 rems or more, was also notedin some cases.

7.40 Those patients in Japan who sur-vived for 3 to 4 months, and did not suc-cumb to tuberculosis, lung disease, orother complications, gradually recovered.There was no evidence of permanent lossof hair, and examination of 824 survivorssome 3 to 4 years later showed that theirblood composition was not significantlydifferent from that of a control group in acity not subjected to nuclear attack.

7.41 Very large doses of whole-body ra-diation (approximately 5,000 rems or more)result in prompt changes in the centralnervous system. The symptoms are hyper-

excitability, ataxia (lack of muscular coor-dination), respiratory distress, and inter-mittent stupor. There is almost immediateincapacitation, and death is certain in afew hours to a week or so after the acuteexposure. If the dose is in the range from1,000 to roughly 5,000 rems, it is the gas-trointestinal system which exhibits theearliest severe clinical effects. There is theusual vomiting and nausea followed, inmore or less rapid succession, by prostra-tion, diarrhea, anorexia (lack of appetiteand dislike for food), and fever. As ob-served after the nuclear detonations inJapan, the diarrhea was frequent and se-vere in character, being watery at firstand tending to become bloody later; how-ever, this may have been related to preex-isting disease. Thus, for

large dose (over 1,000 rems) : survivalimprobable

7.42 The sooner the foregoing symp-toms of radiation injury develop thesooner is death likely to result. Althoughthere may be no pain during the first fewdays, patients experience malaise, accom-panied by marked depression and fatigue.At the lower end of the dose range, theearly stages of the severe radiation illnessare followed by a latent period of 2 or 3

days (or more), during which the patientappears to be free from symptoms, al-though profound changes are taking placein the body, especially in the blood-form-ing tissues. This period, when it occurs, isfollowed by a recurrence of the earlysymptoms, often accompanied by deliriumor coma, terminating in death usuallywithin afew days to 2 weeks.

EFFECTS OF RADIATION ON BLOODCONSTITUENTS

7.43 Among the biological conse-quences of exposure of the whole body to asingle dose of nuclear radiation, perhapsthe most striking and characteristic arethe changes which take place in the bloodand blood-forming organs. Normally, thesechanges will occur only for doses greaterthan 25 rems. Much information on thehematological response of human beingsto nuclear radiation was obtained after

1 0 rs105

the nuclear explosions in Japan and alsofrom observations on victims of laboratoryaccidents. The situation which developedin the Marshall Islands in March 1954,however, provided the opportunity for avery thorough study of the effects of smalland moderately large doses of radiation(up to 175 rems) on the blood of humanbeings. The descriptions given below,which are in general agreement with theresults observed in Japan, are basedlargely on this study.

7.44 One of the most striking hemato-logical changes associated with radiationinjury is in' the number of white bloodcells. Among these cells are the neutro-phils, formed chiefly in the bone marrow,which are concerned with resisting bacte-rial invasion of the body. The number ofneutrophils in the blood increases rapidlyduring the course of certain types of bacte-rial infection to combat the invading orga-nisms. Loss of ability to meet the bacterialinvasion, whether due to radiation or anyother injury, is a very grave matter, andbacteria which are normally held in checkby the neutrophils can then multiply rap-idly, causing serious consequences. Thereare several types of white blood cells withdifferent specialized functions, but whichhave in common the general property ofresisting infection or removing toxic prod-ucts from the body, or both.

7.45 After the body has been exposed toradiation in the sub-lethal range, i.e.,about 200 rems or less, the total number ofwhite blood cells may show a transitoryincrease during the first 2 days or so, andthen decrease below normal levels. Subse-quently the white count may fluctuate andpossibly rise above normal on occasions.During the seventh or eighth weeks, thewhite cell count becomes stabilized at lowlevels and a minimum probably occurs atabout this time. An upward trend is ob-served in succeeding weeks but completerecovery may require several months ormore.

7.46 The neutrophil count parallels thetotal white blood cell count, so that theinitial increase observed in the latter isapparently due to increased mobilizationof neutrophils. Complete return of the106

number of neutrophils to normal does notoccur for several months.

7.47 In contrast to the behavior of theneutrophils, the cumber of lymphocytes,produced in parts of the lymphatic tissuesof the body, e.g., lymph nodes and spleen,shows. a sharp .drop soon after exposure toradiation. The lymphocyte count continuesto remain considerably below normal forsevere' months and recovery may requiremany months or even years. However, tojudge from the observations made in Ja-pan, the lymphocyte count of exposed indi-viduals 3 or 4 years after exposure was notappreciably different from that of unex-posed persons.

7.48 A significant hematologicalchange also occurs in the platelets, a con-stituent of the, blood which plays an impor-tant role in blood clotting. Unlike the fluc-tuating total white count, the number ofplatelets begins to decrease soon after ex-posure and falls steadily and reaches aminimum at the end of about a month. Thedecrease in the number of platelets is fol-lowed by phrtial recovery, but a normalcount may not be attained for severalmonths or even years after exposure. It isthe decrease in the platelet count whichpartly explains the appearance of hemor-rhage and purpura in radiation injury.

7.49 The red blood cell (erythrocyte)count also undergoes a decrease as a re-sult of radiation exposure and hemor-rhage, so that symptoms of anemia, e.g.,pallor, become apparent. However, thechange in the number of erythrocytes ismuch less striking than that which occursin the white blood cells and platelets, espe-cially for radiation doses in the range of200 to 400 rems. Whereas the response inthese cells is rapid, the red cell countshows little or no change for several days.Subsequently, there is a decrease whichmay continue for 2 or 3 weeks, followed bya gradual increase in individuals who sur-vive.

7.50 As an index of severity of radia-tion exposure, particularly in the suble-thal range, the total white cell or neutro-phil co,unts are of limited usefulness be-cause of the wide fluctuations and the factthat several weeks may elapse before the

1 0 ;)

maximum depression i observed. Thelypmphocyte count is of more value in thisrespect, particularly in the low close range,since depression occurs within a few hoursof exposure. However, a marked decreasein the number of lymphocytes is observedeven with low doses and there is relativelylittle difference with large doses.

7.51 The platelet count, on the otherhand, appears to exhibit a regular pattern,with the maximum depression being at-tained at approximately the same time forvarious exposures in the sublethal range.Furthermore, in this range, the degree ofdepression from the normal value isroughly proportional to the estimatedwhole-body dose. It has been suggested,therefore, that the platelet count mightserve as a convenient and relatively sim-ple direct method for determining the se-verity of radiation injury in the sublethalrange. The main disadvantage is that anappreciable decrease in the platelet countis not apparent until some time after theexposure.

LATE EFFECTS OF IONIZING RADIATION

7.52 There are a number of conse-quences of nuclear radiation which maynot appear for some years after exposure.Among them, apart from genetic effects,are the formation of cataracts, non-spe-cific life shortening, leukemia, other formsof malignant disease, and retarded devel-opment of children in utero at the time ofthe exposure. Information concerningthese late effects has been obtained fromcontinued studies of various types, includ-ing those in Japan made chiefly under thedirection of the Atomic Bomb CasualtyCommission.'

7.53 The Atomic Bomb Casualty Com-mission was established in 1947 to providesurveys and studies on the delayed effectsof the A-bombs. Over 400 reports had beenissued by 1973. A nationwide enumerationwas made in Japan at the time of the 1950national census to identify who was in

The Atomic Bomb Casualty Commission of the U.S. National Acad-emy of Sciences-National Research Council is sponsored by the AtomicEnergy Cornmitision and administered in cooperation with the Japa-nese National Institut...! of Health. One of its purposes is to study thelong-term effects et exposure to nuclear radiation,

Hiroshima and Nagasaki at the time ofburst. The major AtoMic Bomb CasualtyCommission studies relate to the survivorswho were alive during the initial survey,about five years after the burst. There-fore, the sample excludes the more se-verely injured who. died prior to .1950.These exposed people have been studied,through both a biennial physical examina-tion and after death by an autopsy pro-gram. Because of different latent periodsthe effects of radiation have developedwith the years since 1947. For example, inthe 1970's, as leukemia decreases, malig-nant neoplasms (tumors) are rising rap-idly, for those exposed in utero or in child-hood. Some of the most significant find-ings from various studies are extractedhere in paragraphs 7.54-7.61 from the 1973technical report of the Atomic Bomb Cas-ualty Commission's report "Radiation Ef-fects on Atomic Bomb Survivors."

GENETIC EFFECTS

7.54 Significant effects of parental ex-posure to the A-bomb on stillbirth or in-fant mortality rates, birth weight of child,or on the frequency of congenital malfor-mations have not been detected. The sexratio (ratio of male to female babies) wasexpected to decrease if the mother hadbeen irradiated, and to increase with pa-ternal irradiation. An earlier study sug-gested such a shift, but additional datafailed to confirm this hypothesis. No rela-tionship has been observed between pa-rental exposure and the mortality of chil-dren. No significant increase in leukemiaincidence has been observed in the off-spring of persons exposed to A-bomb ra-diation. A preliminary study of the off-spring of A-bomb survivors, showed no evi-dence of radiation effects on chromosomes.Recent studies show white corpuscle dam-age after 20 years (see 7.61).

RADIATIONINJURIES

7.55 Three major symptoms of acuteradiation expolire were observedloss ofhair, bleeding, and mouth lesions. Acuteradiation symptoms increased from 5% to10% among those exposed to total dose of

107

110

50 rem to 50% to 80% of thosg.,withahout,300 rem exposure, after which the propor-tion leveled off.

DELAYED EFFECTS ON GROWTH ANDDEVELOPMENT

7.56 Head circumference and heightwere significantly smaller in children inutero whose mothers were exposed andevidenced major radiation symptoms. Con-sistently smaller head and chest circum-ferences, weight, standing and sittingheights at ages 14 to 15 years were foundamong Nagasaki children whose motherswere exposed to high doses. Height,weight and head circumferences at 17years of age were significantly smaller inthe Hiroshima in utero children whosemothers were exposed. Decreased heatcircumference was most prominent amongthose in the first trimester of gestation attime of burst (ATB). Body size was smallerand body maturity advanced in the Hiro-shima exposed children. Adult height wassignificantly less among Hiroshima chil-dren 0-5 years of age ATB (at time ofburst) exposed to high doses. Dose effectdeclined with increasing age ATB, butadult weight was less regardless of ageATB. Tissue samples from the exposedpopulation suggest accelerated ageingamong those exposed. There was no radia-tion effect on bone growth among thoseexposed to radiation in utero ATB.

DELAYED EFFECTS OF DISEASEOCCURRENCE

7.57 The first demonstrated delayed ef-fects of the A- bombs were radiation cata-racts in about 2'12% of survivors within1000 meters from ground zero ATB. Cata-racts were the only delayed manifesta-tions of ocular injury from the A-bomb.The latent period for subjective disturb-ances from cataracts appears to have beenabout two years. Prevalence of mental re-tardation was high in those exposed inutero less than 1500 meters from groundzero. Mental retardation .was more fre-quent in those exposed between the 6thand 15th weeks of pregnancy, the period ofbrain development. For m utero children,108

the death rate for all causes, especiallyamong infants, increased with intensity ofradiation exposure of the mother. How-ever, no increase in mortality from leuke-mia and other cancers was observed. Norelationship between rheumatoid arthritisand radiation dose-has-been found. A neg-ative finding does not mean that certaineffects will not occur later. Abnormalitiesof the minute surface blood vessels werefound in those under 10 years ATB whowere exposed to 100 rem or more. Lip andtongue mucous membrances were morefrequently affected than were nail foldand eyelids. These findings suggest thatA-bomb exposure affected the entire vas-cular system. There was no evidence of arelationship between the prevalence ofcardiovascular diseases and radiation ex-posure, or between mortality from cardiov-ascular diseases and radiation.

111

NEOPLASMS

7.58 There were minor elevations inmortality from causes other than neo-plasms (abnormal growth) but, all in all,there was little evidence of radiation ef-fect on other causes of death, includingtuberculosis, stroke, and other diseases ofthe circulatory system. Lung cancer mor-tality increased with dose. This increasewas particularly significant for those ex-posed at ages 35 years and over ATB. Theoccurrence of thyroid cancer was higher inwomen than in men and showed a signifi-cant elevation with the increase in dose.For those less than 20 years ATB, no sexdifference for thyroid cancer was evident.Salivary gland tumors increased morethan five-fold among survivors exposed tohigh radiation doses compared with thenonirradiated population. The relativerisk of breast cancer was significantlyhigher among the heavily irradiatedwomen. Women who were young at thetime of the bomb are now entering theages of high risk from breast cancer. Norelationship has been found to date be-tween radiation dose and prevalence ofcancers of the stomach, gall bladder andbile duct, liver, bone, and skin. Mortalityfrom disease was higher among survivorswho received large radiation doses than

among those with small doses or those notin the cities. Excessive mortality was espe-cially high for leukemia, where the radia-tion effect appeared to be present evenamong those estimated to have received10-49 rem. Mortality from cancer apart-from leukemia -was-also elevated in survi-vors with large radiation doses, but couldbe demonstrated with reliability onlyamong those with doses exceeding 200rem.

LEUKEMIA

7.59 Leukemia rates in the high dosegroups have declined persistently duringthe period 1950 to 1970, but have notreached the level experienced by the gen-eral population. However, death rates forcancer of other sites have increasedsharply in recent years. The latent periodfor radiation induced cancers other thanleukemia appears to be 20 years or more.There was increased leukemia with a dose-response relationship with the peak occur-ring about six years after exposure. Theeffect was greatest among those exposedduring childhood. The lowest dose cate-gory' with a high frequency of leukemiawas 20-49 rem. This effect at 20-49 remwas found in Hiroshima where neutronsconstituted a substantial fraction of thetotal dose. In Nagasaki, exposure to neu-trons was very small and no cases of leu-kemia occurred among survivors exposedto 5-99 rem.

MALIGNANT NEOPLASMS

7.60 After a latent period of about 15years, children who received radiationdoses of 100 rem or more have begun todevelop an excessive number of malignantneoplasms. Now, 25 years after exposure,the accumulated increase is most striking,with no evidence that a peak has beenreached. During the next 10 years, thesepersons will be entering ages when cancerincidence ordinarily begins to increase.Forty cases of anemia were confirmed inA-bomb survivors in a 20-year period, butthe increase in risk due to radiation expo-sure was not significant when compared tothe population. The prevalence of thyroid

disease increased with dose among Hiro-shima females and among those 0-19 yearsATB in Nagasaki. An increase in preva-lence of miscellaneous eye diseases afterradiation exposure was noted, exceptamong females age 50 or more ATB.

OTHER FINDINGS

7.61 No consistent differences havcebeeri found by radiation exposure for preg-nancy, birth and stillbirth rates, and zeropregnancies. Studies of cultured lympho-cytes (white corpuscles) have demon-strated that radiation induced chromo-some changes still persist more than 20years after exposure. Furthermore, theirfrequency appears to be proportional tothe exposure close. A high proportion ofthose in utero whose mothers received adose of at least 100 rem evidenced complexchromoso-nal abnormalities as comparedto the comparison groups. There has beenno manifestation of clinical disease associ-ated with chromosomal abnormalities.

EXTERNAL HAZARD: BETA BURNS

7.62 Injury to the body from externalsources of beta particles can arise in twogeneral ways. If the beta-particle emit-ters, e.g., fission products in the fallout,come into actual contact with the skin andremain for an appreciable time, a form ofradiation damage, sometimes referred toas "beta burn," will result. In addition, inan area of extensive early fallout, thewhole surface of the body will be exposedto beta particles coming from many direc-tions. It is true that clothing will atten-uate this radiation to a considerable ex-tent; nevertheless, the whole body couldreceive a large dose from beta particleswhich might be significant.

7.63 Valuable information concerningthe development and healing of beta burnshas been obtained from observations ofthe Marshall Islanders who were exposedto fallout in March 1954. Within about 5hours of the burst, radioactive materialcommenced to fall on some of the islands.Although the fAllout was observed as awhite Powder, consisting largely of parti-cles of lime (calcium oxide) resulting from

109

the decomposition of coral (calcium car-bonate) by heat, the isalnd inhabitants didnot realize its significance. Because theweather was hot and damp, the Mar-shalese remained outdoors; their bodieswere moist and they wore relatively littleclothing. As a result, appreciable amountsof fission products fell upon their hair andskin and remained there for a considerabletime. Moreover, since the islanders, as arule, did not wear shoes, their bare feetwere continually subjected to contamina-tion from fallout on the ground.

7.64 During the first 24 to 48 hours, anumber of individuals in the more highlycontaminated groups experienced itchingand a burning sensation of the skin. Thesesymptoms were less marked among thosewho were less contamined with early fal-lout. Within a day to two all skin symp-toms subsided and disappeared, but afterthe lapse of about 2 to 3 weeks, epilationand skin lesions were apparent on theareas of the body which had been contaim-inated by fallout particles. There was ap-parently no erythema, either in the earlystages (primary) or later (secondary), asmight have been expected, but this mayhave been obscured by the natural colora-tion of the skin.

7.65 The first evidence of skin damagewas increased pigmentation, in the form ofdark colored patches and raised areas (ma-cules, papules, and rasied plaques). Theselesions developed on the exposed parts ofthe body not protected by clothing, andoccurred usually in the following order:scalp (with epilation), neck, shoulders,depressions in the forearm, feet, limbs,and trunk. Epilation and lesions of thescalp, neck, and foot were most frequentlyobserved (see Figures 7.65a and 7.65b).

7.66 In addition, a bluish-brown pig-mentation of the fingernails was very com-mon among the Marshallese and alsoamong American Negroes. The phenome-non appears to be a radiation responsepeculiar to the dark-skinned races, since itwas not apparent in any of the whiteAmericans who were exposed at the sametime. The nail pigmentation occurred in anumber of individuals who did not haveskin lesions. It is probable that this was110

44'

FIGURE 7.65a.Beta burn on neck shortly afterexposure.

FIGURE 7.65b.Beta burn on feet shortly afterexposure.

caused by gamma rays, rather than bybeta particles, as the same effect has beenobserved in dark-skinned patientsundergoing ( -ray treatment in clinicalpractice.

7.67 Most of the lesions were superfi-cial without blistering. Microscopic exami-nation at 3 to 6 weeks showed that thedamage was most ,marked in the outerlayers of the skin (epidermis), whereasdamage to the deeper tissue was much lesssevere. This is consistent with the shortrange of beta particles in animal tissue.After formation of dry scab, the lesionshealed rapidly leaving a central depig-mented area, surrounded by an irregularzone of increased pigmentation. Normal

FIGURE 7.68a.Beta burn on neck after healing.

pigmentation gradually spread outward inthe course of a few weeks.

7.68 Individuals who had been morehighly contaminated developed deeper le-sions, usually on the feet or neck, accom-panied by mild burning, itching and pain.These lesions were wet, weeping, and ul-cerated, becoming covered by a hard, dryscab; however, the majority healed readilywith the regular treatment generally em-ployed for other skin lesions not connectedwith radiation. Abnormal pigmentation ef-fects persisted for some time, and in sev-

FIGURE 7,68b.Beta burn on feet after healing.

114

eral cases about a year elapsed before thenormal (darkish) skin coloration was re-stored (see Figures 7.68a and 7.68b).

7.69 Regrowth of hair, of the usualcolor (in contrast to the skin pigmentation)and texture, began about 9 weeks aftercontamination and was complete in 6months. By the same time, nail discolora-tion had grolArn out in all but a few individ-uals. Seven years later, there were only 10cases which continued to show any effectsof beta burns, and there was no evidenceof malignant changes. Blood studies ofplatelets and red blood cells indicated lev-els lower than average at 5 years afterexposure; at 7 years after exposure theplatelets continued to be slightly de-pressed. It thus appears that repair ofbone marrow injury was not complete atthis time. In the 1961 examination of theMarshallese people there was a possibleindication of bone growth retardation inchildren who were babies at the time ofthe explosion.

INTERNAL HAZARD

7.70 Wherever fallout occurs there is achance that radioactive material will en-ter the body through the digestive tract(due to the consumption of food and watercontaminated with fission products),through the lungs (by breathing air con-taining fallout particles), or throughwounds or abrasions. It should be notedthat even a very small quantity of radioac-tive material present in the body can pro-duce considerable injury. Radiation expo-sure of various organs and tissues frominternal sources is continuous, subjectonly to depletion of the quantity of activematerial in the body as a result of physical(radioactive decay) and biological (elimina-tion) processes. Furthermore, internalsources of alpha emitters, e.g., plutonium,or of beta particles, or soft (low-energy)gamma-ray emitters, can dissipate theirentire energy within a small, possibly sen-sitive, volume of body tissue, thus causingconsiderable damage.

7.71 The situation just described issometimes aggravated by the fact thatcertain chemical elements tend to concen-

1 1 I

trate in specific cells or tissues, some ofwhich are highly sensitive to radiation.The fate of a given radioactive elementwhich has entered the blood stream willdepend upon its chemical nature. Radioso-topes of an element which is a normalconstituent of the body will follow thesame metabolic processes as the naturallyoccurring, inactive (stable) isotopes of thesame element. This is the case, for exam-ple, with iodine which tends to concentratein the thyroid gland.

7.72 An element not usually found inthe body, except perhaps in minute traces,will behave like one with similar chemicalproperties that is normally present. Thus,among the absorbed fission products,strontium and barium, which are similarchemically to calcium, are largely depos-ited in the calcifying tissue of bone. Theradioisotopes of the rare earth elements,e.g., cerium, which constitute a considera-ble proportion of the fission products, andplutonium, which may be present to someextent in the fallout, are also 'bone-seek-ers." Since they are not chemical ana-logues of calcium, however, they are de-posited to a smaller extent and in otherparts of the bone than are strontium andbarium. Bone-seekers, are, nevertheless,potentially very hazardous because theycan injure the sensitive bone marrowwhere many blood cells are produced. Thedamage to the blood-forming tissue thusresults in a reduction in the number ofblood cells and so affects the entire bodyadversely.

7.73 The extent to which early falloutcontamination can get into the bloodstream will depend upon two main factors:(1) the size of the particles, and (2) theirsolubility in the body fluids. Whether thematerial is subsequently deposited insome specific tissue or not will be deter-mined by the chemical properties of theelements present, as indicated previously.Elements which do not tend to concen-trate in a particular part of the body areeliminated fairly rapidly by natural proc-esses.

7.74 The amount of radioactive mate-rial absorbed from early fallout by inhala-tion appears to be ,relatively small. The1 1 2

reason is that the nose can filter out al-most all particles over 10 microns (0.001centimeter) in diameter, and about 95 per-cent of those exceeding 5 microns (0.0005centimeter). Most of the particles descend-ing in the fallout during the critical periodof highest activity, e.g., within 24 hours ofthe explosion, will be considerably morethan 10 microns in diameter. Conse-quently, only a small proportion of theearly fallout particles present in the airwill succeed in reaching the lungs. Fur-thermore, the optimum size for passagefrom the alveolar (air) space of the lungsto the blood stream is as small as 1 to 2microns. The probability of entry into thecirculating blood of fission products andother weapon residues present in the earlyfallout, as a result of inhalation, is thuslow. Any very small particles reaching thealveolar spaces may be retained there orthey may be removed either by physicalmeans, e.g., by coughing, or by the lym-phatic system to lymph nodes in the me-diastinal (middle chest) area, where theymay accumulate.

7.75 The extent of absorption of fissionproducts and other radioactive materialsthrough the intestine is largely dependentupon the solubility of the particles. In theearly fallout, the fission products as wellas uranium and plutonium are chieflypresent as oxides, many oxides of stron-tium and barium, however, are soluble, sothat these elements enter the bloodstream more readily and find their wayinto the bones.4 The element iodine is alsochiefly present in a soluble form and so itsoon enters the blood and is concentratedin the thyroid gland.

7.76 In addition to the tendency of aparticular element to be taken up by aspecific organ, the main consideration indetermining the hazard from a given ra-dioactive isotope inside the body is thetotal radiation dose delivered while it is inthe body (or specific organ). The most im-portant factors in determining this doseare the mass and half-life of the radioiso-tope, the nature and energy of the radia-tions emitted, and the length of time it

' Even under these conditions, only about 10 percent of the strontiumor barium is actually absorbed.

11,3

stays in the bOdy. This time is dependentupon the "biological half-time" which isthe time taken for the amount of a partic-ular element in the body to decrease tohalf of its initial value due to eliminationby natrual (biological) processes. Combina-tion of the radioactive half life and biologi-cal half-time gives rise to the "effectivehalf-life," defined as the time required forthe amount of a specified radioactive iso-tope in the body to fall to half of itsoriginal value as a result of both radioac-tive decay and natural elimination. Inmost cases of interest, the effective half-life in the body as a whole is essentiallythe same as that in the principal tissue (ororgan) in which the element tends to con-centrate. For some isotopes it is difficult toexpress the behavior in terms of a singleeffective half-life because of their compli-cated metabolic mechanisms in the humanbody.

7.77 The isotopes representing thegreatest potential internal hazard arethose with relatively short radioactivehalf-lives and comparatively long biologi-cal half-times. A certain mass of an isotopeof short radioactive half-life will emit par-ticles at a greater rate than the samemass of another isotope, possibly of thesame element, having longer half-life.Moreover the long biological half-timemeans that the active material will not bereadily eliminated from the body by natu-ral processes. For example, the 'elementiodine has a fairly long biological half-timein many individuals, The actual value var-ies over a wide range, from a few days insome people to many years in others, buton the average it is about 90 days. 'Iodineis quickly taken up by the thyroid glandfrom which it is generally eliminatedslowly. The radioisotope iodine-131, afairly common fission product, has a radio-active half-life of only 8 days. Conse-quently, if a sufficient quantity of thisisotope enters the blood stream it is capa-ble of causing serious damage to the thy-roid gland, because it remains there dur-ing essentially the whole of its radioactivelife.

7.78 At short times after a detonation,other radioisotopes of iodine, e.g., iodine

116

133 and 135, would contribute materiallyto the total dose to the thyroid gland.However, their radioactive half-lives aremeasured in hours, and so they decay toinsignificant levels within a few days oftheir formation. It should be mentionedthat, apart from immediate injury, anyradioactive material fhat enters the body,even if it has a short effective half-life,may contribute to damage which does notbecome apparent for some time.

7.79 In addition to radioidine, the mostimportant potritially hazardous fissionproducts, assuming sufficient amounts getinto the body, fall into two groups. Thefirst, and more significant, contains stron-tium 89, strontium 90, cesium 137, andbarium 140, whereas the second consists ofa group of rare earth and related ele-ments, particularly cerium 144 and thechemically similar yttrium 91.

7.80 Another potentially hazardous ele-ment, which may be present to some ex-tent in the early fallout, is plutonium, inthe form of the alpha-particle emittingisotope plutonium 239. This isotope has along radioactive half-life (24,000 years) aswell as a long biological half-time (about200 years). Consequently, once it is depos-ited in the body, mainly on certain sur-faces of the bone, the amount of plutoniumpresent and its activity decrease at a veryslow rate. In spite of their short range inthe body, the continued action of alphaparticles over a period of years can causesignificant injury. In sufficient amounts,radium, which is very similar to plutoniumin. these respects, is known to cause necro-sis and tumors of the bone, and anemiaresulting in death.

7.81 Experimental evidence indicatesthat nearly all, if not all, inhaled pluton-ium deposits in the lungs where a certainportion, less than 10 percent, remains.Some of this is found in the bronchiallymph nodes. For this reason, the primaryhazard from inhaled plutonium is to thelungs and bronchial lumph nodes. It is ofinterest to note that despite the largeamounts of radioactive material whichmay pass through the kidneys in the proc-ess of elimination, these organs ordinarilyare not greatly affected. By contrast, ura-

1 1 3

nium causes damage to the kidneys, but asa chemical poison rather than because ofits radioactivity.

7.82 Early fallout accompanying thenuclear air bursts over Japan was so insig-nificant that it was not observed. Conse-quently, no information was available con-erning the-potentialities of fission prod-ucts and other weapon residues as inter-nal sources of radiation. Following the in-cident in the Marshall Islands in March1954, however, data of great interest wereobtained. Because they were not aware ofthe significance of the fallout, many of theinhabitants ate contaminated food anddrank contaminated water from open con-tainers for periods up to 2 days.

7.83 Internal deposition of fission prod-ucts resulted mainly from ingestion rathffthan inhalation for, in addition to the rea-sons given above, the radioactive particlesin the air settled out fairly rapidly, butcontaminated food, water, and utensilswere used all the time. The belief thatingestion was the chief source of internalcontamination was supported by the ob-servationson chickens and pigs made soonafter the explosion. The gastrointestinaltract, its contents, and the liver werefound to be more highly contaminatedthan lung tissue.

7.84 From radiochemical analysis ofthe urine of the Marshallese subjected tothe early fallout, it was possible to esti-mate the body burden, i.e., the amountsdeposited in the tissues, of various iso-topegAt was found that iodine 131 madethe major contribution to the activity atthe beginning, but it soon disappeared be-cause of its relatively short radioactivehalf-life (8 days). Somewhat the same wastrue for barium 140 (12.8 days half-life),but the activity levels of the strontiumisotopes were more persistent. Not only dothese isotopes have longer radioactivehalf-lives, but the biological half-time ofthe element is also relatively long.

7.85 No elements other than iodine,strontium, barium, and the rare earthgroup were found to be retained in appre-ciable amounts in the body. Essentially allother fission product and weapon residueactivities were rapidly eliminated, because114

of either the short effective half-lives ofthe radioisotopes, the sparing solubility ofthe oxides, or the relatively large size ofthe fallout particles.

7.86 The body burden of radioactivematerial among the more highly contami-nated inhabitants of the Marshall Islandswas never very large and it decreasedfairly rapidly in the 'course of 2 or 3months. The activity of the strontium iso-topes fell off somewhat more slowly thanthat of the other radioisotopes, because ofthe longer radioactive half-lives andgreater retention in the bone. Neverthe-less, even strontium could not be regardedas a dangerous source of internal radia-tion in the cases studied. At 6 monthsafter the explosion, the urine of most indi-viduals contained only barely detectablequantities of radioactive material.;

7.87 The most heavily exposed group,some 64 Marshallese inhabitants of Ron-gelap atoll, received an estimated 175 remwhole-body dose before being evacuated.While internal contamination was of con-cern in 1954, the consensus of the scien-tists and medical people was that internalburdens of radionuclides were not likely toproduce injury, even in the heavily ex-posed group. All early symptoms were dueto whole-body exposure doses and to skin-'deposited fallout particles. Based on anal-ysis of urine samples, it was accepted thatthe Marshall Island people were fully re-covered from their accidental exposure tothermonuclear fallout in 1954.

7.88 In 1963 a thyroid nodule was-dis-covered during routine examination of a12-year-old-girl, and in the following yearsadditional cases were discovered duringthe annual medical surveys. By 1969, 15 ofthe 19 children who had been under 10years of age at the time of exposure haddeveloped thyroid nodules, and anothertwo had severe atrophy of the thyroidgland. The method of treatment of all 15nodule cases was either partial or totalremoval of the thyroid gland.

7.89 No children in the less heavily ex-posed group, with whole-body doses up toabout 70 rem, have developed thyroid nod-ules to date. Adults in the Rongelap grouphave developed thyroid nodules, but the

rate of incidence has been less than 'I)the rate for children.

7.90 It seems clear that the course* ofthe thyroid abnormalities was beta irra-diation by the radioiodines concentratedin the thyroid gland after ingestion and/orinhalation. It is likely there is more trou-ble ahead over the years for the MarshallIslanders, both adults who were heavilyexposed and those who were children inthe 70 rem exposure group. It is thoughtthe latency period for neoplasms is in-versely related to dose. This theoreticalrule of latency may explain the bunchingof thyroid effects from 9 to 14 years afterexposure.

7.91 The experienceof the Marshallesechildren illustrates one combination ofconditions leading to a serious radioiodinethreat in nuclear warfare. The childrenwere exposed, for the first two days, to allof the radiological effects of the falloutfield, estimated to be 100 R/hr at 1 hourafter detonation. They received whole-body exposure of about 175 rem. The airthey breathed, during and after falloutdeposition was unfiltered. They ate con-taminated food and drank contaminatedwater.

7.92 Had the exposure at Rongelapbeen even a factor of three higher, morethan half of the exposed people wouldhave died within a month from the whole-body gamma radiation exposure. Studiesindicate that in a nuclear attack againstthe U.S., exposure could be a factor of 30or higher than at Rongelap in some areas.Fallout shelters having a protection factorof forty would be necessary to limit theshelter period whole-body exposure to 175rem, i.e., the dose that the people at Ron-gelap received.

7.93 Protection against the threat ofinhaled and ingested iodines could be pro-vided if (1) only filtered air were breathed,and (2) only preattack-stored food andwater were consumed for 30-40 days or 4-5I"' half-lives. Since vapor filters are notprovided in fallout shelters, any radioiod-ine in the gaseous state would reach the

Final Report, Inhalation of Radioiodine from Fallout: Hazards andCountermeasures, Defense Civil Preparedness Agency. Washington,D.C. 20301, August 1972, Number 2380.

118

shelterees: particles stopped by particlefilters could still release their radioiodineinto the ventilation system. Although it isnot possible to predict, even within orderof magnitude, the thyroid doses that couldbe caused by inhalation of fallout radioiod-ines, the threat of inhaled radioiodines isreal. Fortu-ately, this threat is likely toaffect only small areas of the country andit can be countered safely and inexpen-sively by the timely administration of sta-ble "blocking" iodine to reduce the thyroiduptake of radioiodines. In general, the up-take of radioiodines by inhalation is be-lieved to be minor compared to that fromingestion.

WHOLE-BODY EXPOSURE

7.94 There is agreement among mostauthorities that a single whole-body expo-sure of 200 R will not affect the averageadult to the extent that he is incapable ofperforming his ordinary activities. In fact,whole-body exposures of 200-300 R havebeen given to many patients with ad-vanced cancer without any manifestharmful effect on their physical condition.Changes in the blood count occurred, aswas expected, but these were not suffi-cient to require medical treatments. TheMarshall Islanders who had the largestexposure to fallout, received about 175 Rover a period of 36 hours. In this group,which included people of all ages, the onlyevidence of acute radiation sickness wasvomiting on the day fallout occurred(about 10 percent reported this symptom)and changes in the white blood cell countand platelet count several weeks later.There is also general agreement that asingle whole-body exposure of 200 R or lessshould not cause radiation sickness severeenough to require medical care in the ma-jority (9 out of 10) of healthy adults.

7.95 The expected results of variousradiation exposures, if received over var-ious periods of time, are shown in thefollowing figure (Figure 7.95). (This figureis tentative; it may be modified as a resultof recommendations currently being devel-oped by the National Council of RadiationProtection and Measurements. The num-bers, however, are believed to be realistic.)

1 1 5

Roentgen ExposureAcute in AnyEffects

.

1 Week

.

1 Month 4 Months

Medical Care Not Needed 150 200 300

Some Need Medical CareFew if Any Deaths 250 350 500

Most Need Medical Care50% + Deaths 450 600

Little or no practical consideration

FIGURE 7.95'.Radiation Exposure Doses.

7.96 To illustrate use of the figure,most people receiving no more than a totalof 150 R during a time interval less than aweek (1 hour, 1 day, 3 clays, for instance)are not expected to need medical care norto become ineffective in work perform-ance. Also, people receiving more than 500R during one month will need medicalcare, and 50% or more may die.

7.97 This "penalty figure" is intendedfor use by civil preparedness officials dur-ing a war emergency to provide them asimple and straightforward basis for tak-ing into account the radiological elementsof the problem. For example, replenish-ment of a shelter's inadequate water sup-ply might be justified if a small crew coulddo so, and if each member's total week'sexposure could be kept to less than 150 R,or the month's exposure less than 200 R.

7.98 It is known that radiation in-creases the chances of genetic damage and

',Taken from DCPA Attack Environment Manual, Chapter 1.

1 1 6

other long-term effects. These effects arecomparatively minor. In a war emergency,first minimize the number of deaths andsecond, keep the number of people forwhom medical care is needed as small aspossible. When circumstances permit, pre-ferred consideration should be given tochildren and adults still capable of pro-creation. As conditions permit, emergencymeasures should be terminated and nor-mal standards reinstituted.

REFERENCES

The Effects of Nuclear Weapons.Glas-stone, Samuel, 1964.

DCPA Attack Environment Manual.Radiation Effects on Atomic Bomb Sur-

vivors.Technical Report 6-73, AtomicBomb Casualty Commission, 1973.

Final Report-Inhalation of Radioiodinefrom Fallout: Hazards and Countermea-sures.DCPA, 1972, No. 2380.

119

EXPOSURE AND EXPOSURE RATE' CALCULATIONS

Up to this point we have learned thatthe effects of radiation exposure are im-portant and we have seen what the medi-cal consequences are for exposures overdifferent periods of time. We need a meansof calculation that will assist us in meet-ing guidelines established for emergencyworkers. Tall order? Complicated mathe-matics? Not at all. At least not at the endof this chapter because by then we willhave learned:

HOW to determine exposure and ex-posure rates

HOW to predict future exposure andexposure rates

WHEN can someone leave shelter andfor how long

WHY prediction and measurementare possible

INTRODUCTION

8.1 In chapter 6 we saw that falloutarrives at particular locations with re-spect to ground zero at various times afterburst, depending on such factors as dis-tance, meteorological conditions, etc.

8.2 It was also shown that radioactivecontamination from fallout could deny theuse of considerable areas for an apprecia-ble period of time. Thus, even without thematerial destruction from blast or thermalradiation, many areas, facilities and equip-ment could not be used or occupied forsome time without extreme danger.

8.3 In deciding what protective meas-ures should be taken, including surveymonitoring operations in an area contami-nated with fallout, it is necessary:

1. To make some estimate of the permis-sible time of stay for a prescribed ex-posure, or

CHAPTER 8

2. To determine the exposure thatwould be received in a certain timeperiod.

3. To determine an "entry time" for aprescribed exposure and a prescribedstay time.

8.4 If the radiation exposure rate fromthe fission products produced by a singleweapon is known at a certain time in agiven location; this knowledge may beused to estimate the exposure rate at anyother time at thelsame location assumingthat there has been no externally pro-duced change in the fallout (i.e., from addi-tional contamination or by decontamina-tion). In any such calculation, the conceptof RADIOACTIVE DECAY IS VERY IM-PORTANT.

DECAY OF FISSION PRODUCTS

8.5 As we saw in Chapter 2, each ra-dioisotope has a characteristic decayscheme (h0 .1f-life). These range from a fewmillionths of a second to millions of years.When a number of different radioisotopesare presentin this case the fission prod-ucts of the bomb (fallout)no one half-lifeapplies for the composite. For the fissionproducts, the short-lived radioisotopes pre-dominate in the period immediately follow-ing the burst. Since their half-lives (decayrates) are so short (rapid), the radiationlevel falls off quickly after the detonation.And as these short -lived radioisotopes ex-pend themselves through decay, thelonger half-life isotopes form an increasingproportion of the fission products and therate of decay of the fission products de-creases. Because of this pattern of decay,the material deposited on the ground atincreasing times after the burst will beless and less radioactive.

12u

1 1 7

8.6 In calculating the radiation expo-sure (or exposure rate) due to fallout fromfission products, the gamma rays (becauseof their long range and penetrating power)are of greater significance than the betaparticles, provided of course that the ra-dioactive material is not actually in con-tact with the skin or inside the body.

8.7 Even though there are differentproportions of gamma ray emitters amongthe radioisotopes in fallout at differentperiods of time, the fact that there is apattern of decay does permit the develop-me\nt through estimates or calculations oflevels of exposure and exposure rate atcertain times after a detonation and, infact, permits prediction of exposure andexposure rate with a fair degree of accu-racy. There are variqus ways of coming upwith these estimates or calculations, someemploying a rule of thumb, some employ-ing mathematical formulae, and othersemploying graphic presentations (nomo-grams).

NOTE

No computation of exposure or expo-sure rate should be made until theybegin to decrease. You SHOULD NOTCALCULATE EXPOSURE RATESWHILE THEY ARE INCREASING.Further, calculation is no substitutefor accurate instrument readings.

THE 7:10 RULE OF THUMB

8,8 After exposure rates have begun todecrease, you can get a rough idea of fu-ture rates by using the 7:10 rule Simplystated, this rule is that for every seven-fold increase in time after detonation,there is a ten-fold decrease in exposurerate. Figure 8.8 demonstrates this rule ofthumb.

8.9 Therefore, we see th.at, through useof this rule of thumb, if a 50 R/hr radiationexposure rate exists at three hours afterdetonation, by the end of 21 hours it willhave decreased to 5 R/hr, and by the endof 147 hours it will have decreased to 0.5 R/hr.

118

TIME (410 DECAY RADIATION INTENSITY

1 1000 R/hr

7 1/10 100 R/hr

49 1/100 10 R/hr

343 1/1000 1 R/hr

FIGURE 8.8.The 7:10 rule of thumb for rate of decay.

STANDARD DECAYTHE EXPOSURE RATE FORMULA

8.10 The following formula is used incalculating exposure rates:

R, =R T"8.11 In this equation:

R = rate at a specific time (T)R, = rate one hour after detonation

(H + 1?T = time (hours) after detonationn = 1.2 (fallout decay exponent)

NOTE

When n is equal to 1.2 the situation isreferred to as standard decay. When nassumes other values nonstandard de-cay conditions exist.

STANDARD DECAYAN EXPOSURERATE PROBLEM

8.12 If the exposure rate at a givenlocation one hour after. detonation was 30R/hr, what would the rate be at this loca-tion 12 hours after detonation?

SOLUTIONR, = 30 R/hrR =?T = 12 hoursn = 1.2

Substitute values in the above formula:R, =RT"30 =R(12)

121

30 = R (19.74)*30

R L52 R/hr19.73

*From Figure 8.14 (12)-12 =19.73

STANDARD DECAYTHE EXPOSUREFORMULA

8.13 The following formula is used incalculating exposure.

E =n

R. (T,'" T21---")

,

1

8.14 In this equation:E = exposure from time T, to T.R, = exposure rate one hour after

detonation (H + 1)T, = time of entryT., = time of exitn = 1.2 (fallout decay exponent)

8.15 As an aid in using either formulapresented above, FigUre 8.14 gives thecomputed values of T1.2 and T°2 for vari-ous selected values of T.

STANDARD DECAYAN EXPOSUREPROBLEM

8.16 What exposure would a monitoringteam receive in a radioactive contami-nated area if the team entered the area 5hours after a nuclear burst and stayed fora period of 10 hours? The exposure rate atH + 1 was 50 R/hr.

SOLUTION

E ?

R, = 50 R/hrT, ,= 5 hoursT = 5 +10 =15 hoursn = 1.2

Substitute values in the above fon-11A:

E = T2'")n 1

122

5E = 50

1.2 1(5-1.2 151-1.2)

5E = 0.2 (5-0.2 15-0.2)

E = 250 (0.725 0.582)**E = (250) (0.143)E = 36 R

**From Figure 8.14 5 -0.2 =0.725 and 15-0.2=0.582

STANDARD DECAYEXPOSURE RATENOMOGRAM

8.17 If, of the factors (1) time afterdetonation, (2) exposure rate at H +1, and(3) exposure rate at a particular time, weknow any two, then the other one can befound by using a nomogram developed spe-cifically for exposure rate calculations.(You will recognize these factors as com-ing from the formula of paragraph 8.10,namely, R,--=R'P'). The nomogram appearsas Figure 8.17 and is based upon thestandard fallout decay exponent of 1.2.

8.18 To use the exposure rate nomo-gram shown in Figure 8.17, connect anytwo known quantities with a straightedgeand read the unknown quantity directly.

STANDARD DECAYAN EXPOSURERATE NOMOGRAM PROBLEM

8.19 If the exfiSsure rate in an area is60 R/hr at H + 5, what will be the rate atH + 10?

8.20 SOlution: With a straightedge, con-nect 60 R/hr on the "Exposure Rate atH + T" column with 5 hours on the "TimeAfter Burst" column. The rate of 410 R/hris read on the "Exposure Rate at H + 1"column. Next, connect, with the straight-edge, 10 hours on the "Time After Burst"column with 410 R/hr on the "ExposureRate at H + 1" column and read the an-swer directly from the "Exposure Rate atH + T" column.

Answer: 26 R/hr.

1 1 9

T =

TIM

EIN

HO

UR

ST

1.2

.T

-0.2

T=

TIM

EIN

HO

UR

ST

1.2

T-a

2T

= T

IME

IN H

OU

RS

T 1

.2T

-0.2

48.0

104.1

0.461

0.1

0.0631

1.586

19.0.

34.23

0.555

49.0

106.7

0.459 ,

0.2

0.1450

1.381

20.0

36.41

0.550

50.0

109.3

0.457

0.3

0.2358

1.273

21.0

38.61

0.544

55.0

122.6

0.449

0.4

0.3330

1.202

22.0

'

40.82

0.539

60.0

136.1

0.441

0.5

0.4352

1.149

23.0

43.06

0.534

65.o

149.8

0.434

0.6

0.5417

1.110

24.o

45.31

0.530

70.0

163.7

0.427

0.7

0.6518

1.074

25.o

47.59

0.525

72.o

169.4

0.425

0.8

0.7651

1.046

26.0

49.89

0.521

75.0

177.8

0.422

0.9

0.8812

1.021

27.0

52.20

0.518

80.0

192.2

0.417

1.0

1.000

1.000

28.D

54.52

0.514

85.0

206.7

0.412

1.5

1.627

0.922

29.0

'56.87

0.510

90.0

211..1

0.407

2.0

2.300

0.871

30.0

59.23

0.506

95.0

236.2

0.402

2.5

3.003

0.833

31.0

61.61

0.503

96.o

239.2

0.401

3.0

3.737

0.803

32.o

64.00

0.500

100.0

251.2

0.398

4.o

5.278

0.758

33.o

66.41

0.497

120.0

312.6

0.384

5.o

6.899

0.725

34.0

68.83

0.494

140.0

376.2

0.372

6.o

8.586

0.698

35.0

71.27

0.491

144.0

389.1

0.370

7.o

10.33

0.678

36.0

73.72

0.488

160.0

442.5,

0.362

8.o

12.13

0.660

37.o

76.18

0.486

168.0

(1 wk)

468.1

0.360

9.o

13.96

0.644

38.0-

78.66

0.483

180.0

508.5

0.354

10.0

15.85

0.631

39.o

81.15

0.480

220.0

577.1

0.347

11,0

17.77

0.619

40.0

83.67

0.478

250.0

754.3

0.332

12.0

19.73

0.608

-o.599

41.0

86.17

0.476

300.0

938.7

0.319

13.0

21.71

42.0

88.70

0.474

336.0

(2 wk)

1075:0

0.313

14.0

23.74

0.590

43.0

91.23

0.472

504.0

43 wk)

1745.0

0.288

15.0

25.78

0.582

44.0

93.79

0.470

672.0

4wk)

2471.0

0.272

16.0

27.86

0.574

45.0

96.35

0.467

720.0

(1 Mo.)

2611.0

0.268

17.0

29.96

0.567

46.0

98.93

0.465

i440.0

(2 Mo.)

6166.0

0.234

18.0

32.09

0.560

47.0

101.5

0.463

2160.0(3 Mo.)

10031.0

9.216

FIG

UR

E 8

.14.

-T'-2

and

T-°

.2 f

or s

elec

ted

valu

esof

T.

"4"

3000 -,-._

2000 -r-

1000

SOO

800 .1--

400

300

200

100 -.-12

SO

80

40

301

20 --

1047

8'-

-r-

4 --I-

3 -.--

Exposers Rat.

at H+t

--

Time After1

3 14

SCO 6--3 8

10

20-1

3040

60r80

Burst

1

231-8 C.

ft SO

10 CO,121620

28c-36

Exposure Rate

at H+1

(R- 2

4

6

8

to

20

30

40

80

SO

too

200

300

400

600

800

1000

2000

3000

5000

FIGURE 8.17.Exposure rate nomogram.

STANDARD DECAYENTRY TIMESTAYTIMETOTAL EXPOSURE NOMOGRAM

8.21 Just as it is possible to develop anomogram for exposure rates and timethrough the use of the exposure rate for-mula and standard fallout decay exponentof 1.2, so can we produce a nomogram forthe exposure formula.

8.22 This nomogram is found in Figure8.22.

8.23 To use this nomogram, connecttwo known quantities with a straightedgeand locate the point on the "E/R," columnwhere the straightedge crosses it. Connectthis point with a third known quantity andread the answer from the appropriate col-

umn.

1241.21

Wel liposere(E)

3

4

a.1

10

20

30

40

GO

BO

100

2 0 0 -

3 0 0

4 0 0

1 0 0 0

Wow. Rote (1 hoer)(RI)

2

4

a .7:7

20

3040

GO

aooo J.

20013001--4001Goo 4--aoo 4

4-moo s-2000- - -3000,

-50001--

R,

.9.7

.6

.5

.4

.3

.2

.01.os

.07

.06

.04

Stay Time (hours)

14

te,

1G

3-T2

ii

.02

FIGURE 8.22.Entry time-stay total-exposure nomogram.

STANDARD DECAYAN ENTRY TIMENOMOGRAM PROBLEM

8.24 The exposure rate in an area atH + 7 is 35 R/hr. The stay time is to be 5hours and the mission exposure is set at 35R. What is the earliest possible entrytime?

8.25 Solution: Find the exposure rateat H + 1 from the Exposure Rate Nomo-gram (Figure 8.17). Connect this value onthe "Exposure Rate at H + 1" column with35 R on the "Total Exposure" column andread 0.1 on the "E/R," column. Connect 0.1on the "E/R," column with 5 hours on"Stay Time" column and read the answerfrom the "Entry Time" column.

Answer: H + 24.

STANDARD DECAY-- A STAY TIMENOMOGRAM PROBLEM

8.26 Entry into an area with an expo-122

Entry Time%.3

rf

.41

1-5

100

40-\

641-1

104-

\

430

sure rate of 100 R/hr at H + 1 will be madeat H + 6. What will be the maximum mis-sion stay time, if the exposure is not toexceed 20 R?

8.27 Solution: Connect 20 R in the "To-tal Exposure" column with 100 R/hr in the"Exposure Rate at H + 1" column andread 0.2 in the "E/R,"colu Connect 0.2in the "E/R," column with 6 hours in the"Entry Time" column, and read the an-swer directly from the "Stay Time" col-umn.

Answer: 2.1 hours.

STANDARD DECAYAN EXPOSURENOMOGRAM PROBLEM

8.28 Find the total exposure for an in-dividual who must work in an area inwhich the exposure rate was 300 R/hr atH + 1. Entry will be made at H + 11 andthe length of stay will be 4 hours.

1'2

8.29 Solution: Connect H H-11 on the"Entry Time" column with 4 hours on the"Stay Time" column and read 0.19 fromthe "E/R," column. Connect 0.19 in the "ElR," column with 300 R/hr on the "Expo-sure Rate at H +1" column and read theanswer from the "Total Exposure" col-umn.

Answer: 60 R.

WHAT METHOD SHOULD MONITORS

USE?

8.30 Nomograms, based on theoreticalfallout radiaton decay characteristics,should be used by monitors when it isnecessary for them to make rough esti-mates of future exposure rates and expo-sures' that might be expected in perform-ing necessary tasks outside the shelter.However, when fallout from several nu-clear weapons, detonated more than 24hours apart is deposited in an area, thedecay rate may differ markedly from theassumed decay rate. For this reason, cal-culations using nomograms should be lim-ited as follows:

a. The time of detonation must beknown with a reasonable degree ofaccuracyplus or minus one hour forforecasts made within the first twelvehours, and plus or minus 2-3 hoursfor later forecasts.

b. If nuclear detonations occur morethan 24 hours apart, predicted ratesmay be considerably in error. In thiscase, use the H hour of the latestdetonation to compute "Time AfterBurst".

c. At the time of calculation, exposurerates must have been decreasing forat least '2-3 hours, and forecastsshould be made for periods no fartherin the future than the length of timethe radiation levels have been ob-served to decrease.

8.31 Have we covered the subject ofexposure and exposure rate calculations?That question prompts another question.What level of the RADEF organizationare we talking about? Monitors? In thatcase, yes, we have covered exposure and

exposure rate calculations. How about theRADEF Officer? Have we taken care ofhim yet? You'll find that answer below.

AN OPEN LETTER TO RADEF OFFICERS

We have arrived at the point whereyou will have to bear down hard. Thisis the point at which your own profes-sional-type RADEF knowledge makesits departure from the standardRADEF know-how that will be sharedby so muily members of your RADEForganization.

The following paragraphs are notimpossible but then neither are theyeasy. If you miss a point, go back andreread it because the basic material isreally here. You will probably notice,here and there, some repetition overthe preceding paragraphs but it isintended as an aid to,-,1301-er -under-,standing.

We will begin with * * *

A REVIEW OF RADIOACTIVE DECAY

8.32 Each radioactive isotope has acharacteristic half-life. These range from afew millionths of a second to millions ofyears. However, when many radioisotopescontribute to the exposure rate, as in thecase of the fission products from a nuclearweapon, no one half-life applies for thecomposite. With fission products there is apredominance of short-lived radioisotopesin the period immediately following theburst; hence the exposure rate decreasesvery rapidly. As these short-lived radioiso-topes expend themselves, the longer half-life isotopes become dominant and the de-cay rate of the fission products decreases.

8.33 We know that radioactive decay ofthe fission products can be estimated us-ing the general equation R, = RT" where R,equals the exposure rate at unit time, Requals the exposure rate at any time Tmeasured from the time of burst, and n isthe fallout decay exponent. Time may bemeasured in any unitsminutes, hours,days, weeks, etc., provided unit time and Tare expressed in the same units.

STANDARD DECAYA WORD ABOUT

THE EXPONENT (1.2)

8.34 Attempts to fit observed decay of

126

123

fallout from actual tests with a generalequation of the form R,=RT" have re-,quired values of n ranging from about 0.9to 2.2. We have learned that attempts topredict the decay of actual fallout fields onthe basis of any given decay law (i.e.,assuming some constant value for n) arealmost certain to be grossly inaccurate.The value of n will vary with bomb design,the amount and type of neutron-inducedactivity, fractionation, and in a particulararea, with weathering and decontamina-tion.

8.35 For planning purposes, a value ofn = 1.2 is frequently used and, for plan-ning, this value is quite satisfactory. How-ever, accurate information of exposurerates and rates of decay must depend onrepeated monitoring under the same condi-tions at the same locations.

PLOTTING THE EXPOSURE RATE HISTORY

8.36 Since the fallout at any locationmay consist of radioactive material fromseveral different weapons detonated atmaterially different times, it will be im-practical to keep track of the individualcontributions and ages of each set of fis-sion products comprising the fallout. Themost practical method of forecasting expo-sure rates under these conditions appearsto be based upon the technique of plottingobserved rates versus time after detona-tion on log-log paper and extrapolating theplotted curve.

8.37 Plots of this type for two or threerepresentative points across a communitywill generally be adequate. If the require-ment exceeds this, it may be advantageousto compute the value of the fallout decayexponent n and use the general equationR, =RT" to predict future exposure ratesin areas where the fission product compo-sition is the same.

8.38 R., =11,T,". and Ri=11,:ryn etc. Themost useful form of the general equationwill probably be Applicationof this formula is discussed in a laterparagraph (8.55).

8.39 The procedure for plotting ob-served exposure rates is as follows. FromNUDET (report of time of detonation) re-

124

ports or simply from observations of theflash, the blast wave, or the cloud of thedetonation, the time of burst of mostweapons within a radius of 100 to 200miles will be known. Thus, the RADEFOfficer will know the time of formation ofmost of the fission products in his immedi-ate area and from the current "DF" reporthe will generally know which specific deto-nation is causing the major fallout prob-lem in his community.

8.40 The RADEF Officer can then plotor direct the plotting of observed exposurerates against time on log-log paper. Fu-ture rates can be estimated by projectingthe curve to future times of concern.

8.41 However, as a practical limit, fore-casts of future exposure rates generallyshould be made for periods- no farther inthe future than the length. of time exposurerates have been observed to decrease.

8.42 For example, if exposure rate ob-servations have been decreasing for thepreceding 12 hours, they will be plottedand, provided the plot for the last fewhours approximates a, straight line, thecurve can be extrapolated (extended) for12 additional hours to forecast the ratesduring that time period. Caution must beexercised in extrapolating the curve dur-ing periods of fluctuation.

8.43 If, after a period during which thelogarithmic decay is approximately astraight line, the rate is observed to mate-rially increasethis indicates the arrivalof significant additional fallout. If the ex-posure rate appears to be equal to or lessthan the maximum, exposure rate fromearlier fallout, continue the original plotbased on the "11 hour" of the originalfallout.

8.44 However, if considerable time haselapsed since arrival of the first fallout,and the increase in exposure rate equalsor exceeds the maximum exposure ratefrom earlier fallout, plot a new graph us-ing the estimated H hour of the latestfallout as the reference time.

8.45 After the plot indicates an orderlydecrease (nearly a straight line log-logplot), extrapolation of the curve can againprovide a reasonable basis for estimating

exposure rates for future periods subjectto the above-mentioned restriction.

8.46 It should be emphasized that theactual exposure rate may vary consider-ably from the forecast rate. Thus, opera-tions likely to require high radiaton expo-sures should be carried out on the basis ofobserved rates, not forecast rates. Theforecast is simply a guide to aid a localcoordinator,in planning his forthcomingsurviyal and recovery operations.

8.47 A forecast exposure rate could beconsiderably in error if additional falloutoccurred after the forecast was made or ifthe rate of decay changed materially fromthat indicated by the plots on the log-loggraph.

8.48 The latest fallout analysis, basedupon current exposure rate reports,should be the basis for current operations.Plans for future operations should bebased upon the current fallout analysis,modified according to the forecast from alog-log plot.

A PRACTICAL EXAMPLE

8.49 The following exercise presents ahypothetical situation in which we willpredict future exposure rates from a seriesof radiological reports. (The curve whichwill be used does not necessarily representa fallout decay curve which might be ex-pected in an actual situation.)

8.50 We are giVen certain data as fol-lows:

Time after EPO:311re rate Time aHer Exposure rateburst ( Hours) ( Rd's) burst ( flou Psi (Rills)

1 0 18 3802 0 20 3903 1 22 4104 23 24 4155 '4;50 26 4106 1!':1 28 4057 IV, 30 4008 .qi,' 36 3259 Elli, 42 280

10 ± "4, 48 24012 64t; 54 21014 540 60 185

16 460

1. First, we plot the data as indicated bythe arrows ir, Figure 8.50a.

2. Next, we draw. a smooth curvethrough the plotted points as shownin Figure 8.50b.

3. Now, in order to forecast the expo-sure rate at H + 80 and H + 90, weextend the curve to 90 hours as adotted line. This is shown in Figure8.50c.

4. Assume that we now receive addi-tional monitored data as follows:

burst (hours.)Exposure rate

(Eller)Time after Exporn re rateburst (hours) (RIhr)

70 155 100 103

80 131 110 91

90 115 120 83

5. We plot the additional data.6. Then we draw a smooth curve

through these additional points asshown in Figure 8.50d. Notice thecomparison between the forecast ex-posure rates and the actual up-datedplot.

8.51 The fallout decay exponent n maybe computed directly from the plotted ex-posure rate curve since n is numericallyequal to the slope of the curve. Further, nis constant only when the plotted line isstraight. We can determine n from thegraph by dividing the measured distanceAY in inches by the measured distance AXin inches as indicated in Figure 8.50e.

8.52 Looking at Figure 8.50e, let's de-termine n at H + 110. We see that AY andAX are the vertical and horizontal dis-tances, respectively, covered by the curvein the area of our interest. we measurethese distances in inches, divide AY by AX,and find that n at H + 110 is equal to 1.1.

8.53 Now, if practical, n can be used toforecast exposure rates as indicated in thefollowing example. (A table of logarithmsand a brief explanation of their use isincluded as Figures 8.53a and 8.53b.)

8.54 Before working out our example,go back and reread paragraph 8.38. Youwill find it helpful in solving the example.

8.55 Now for the sample problem in

1.28

125

exposure rate forecasting using a corn- H + 4 days is 108 R/hr; if n = 1.1, predictputed value of n. The exposure rate at the rate at H + 8 days.

R., = 108 R/hr RxT," = R,T,"Tx = 4 days (108) (4) 11= (R,) (8)1.1

= ? log 108 + 1.1 log 4 = log R, + 1.1 log 8= 8 days (2.0334) + 1.1 (.6021) = log R, + 1.1 (.9031)

n = 1.1 log It, = 2.0334 + 0.6623 0.9934 = 1.7023Answer: R,. = 50 R/hr.

EXPOSURE CALCULATION FROM ANEXPOSURE RATE HISTORY CURVE

8.56 DCPA recommended radiologicaldefense reporting procedures provide foraccumulated exposure reports each dayfrom fallout monitoring stations for thefirst six days following an attack.. Thesereports will be based on dosimeter meas;-urements, which are the simplest means ofdetermining exposures. Dosimeters inte-grate the exposure over a period of timeand account directly for the decrease inexposure rates duo to decay.

8.57 However, there may be instanceswhen the RADEF Officer must estimateexposure from a series of exposure ratemeasurements. The following paragraphswill provide a quick and easy method ofestimating such exposures.

8.58 It is relatively simple to forecastexposure rates and, consequently, total ex-posure of individuals when the falloutdecay exponent remains constant overlong periods of time. These estimates, how-ever, are normally made only after falloutis complete.

8.59 If we are concerned with estimat-ing the total exposure for the periods (1) offallout deposition, (2) when the value ofthe fallout decay exponent is changingrapidly, or (3) when fallout from severaldetonations contributes to the exposurerate, calculation of these estimates be-comes more complex.

8.60 A satisfactory estimate of total ex-posure can be obtained by plotting expo-sure rates yersus time after detonationand determining total exposures from thegraph.

126

8.61 First, divide the exposure periodinto small increments. When the slope ofthe curve is changing rapidly, the incre-ments should be small. When the slope isrelatively straight over the exposure pe-riod, the increments may be larger. Theincrements need not be equal in size.

23.62 As a general mule, an inCreni"e-ntshould not exceed one-half of the timefrom detonation to the beginning of theincrement. For example, if the incrementsbegins at H + 10, it should not be largerthan 5 hours. However, if the slope of thecurve changes appreciably during thistime, it may be necessary to use evensmaller increments. During the initial pe-riods of fallout deposition, the incrementsshould be no larger than 1 hour.

8.63 Now look at Figure 8.63 to see howa sample exposure period is broken intoincrement..

8.64 Next, we determine the averageexposure rate within each increment andmultiply this by the elapsed time. This willgive us the exposure for each incrementand the sum of these exposures will giveus the total exposure for the period. Thecalculations involved are presented below.

Average exposureAre rage rate x

Increment exponure ?mit, elapsed lime = expounreA (100+80)+9=90 90x2=180B (80+50),-9=65 65x3=195C (50+30)+2=40 40x5=200

Total 575 R

:

I I I I .1 .1 II II II II .11-

I I I I -

-r

m o

0m

00

00

0o

o o

I.

mo

ufflo

qbal

p In

nN

u III

11

umro

w11

111M

I1.

11I H

I II

MIM

MT

MU

Inr

uir

191

le

iirilr

oJI

MN

hulle

d' m

inm

illdi

Mill

inir

El

:!M

I illu

l. N

M b

liiii

i

iitiE

tillif

filli

filia

llUil

1111

1111

1111

1111

1IH

IPIll

imm

ontim

muf

fnd

mi-

mom

mol

logi

umm

oulli

l-

mill

opL

umm

uno

our

indi

niili

bila

nnE

INE

NN

EM

EM

INIM

EM

ON

NE

INE

MB

igm

EN

IEM

IN 0

it N

iiliM

INPU

NII

IIIO

N"

liiiii

iiiili

E11

1111

1ME

HU

OM

iffi

lllig

hltil

iEN

AM

MIS

1111

0111

1111

BE

IEN

IME

NIC

, E

OM

IMLI

NIii

iirer

MIN

ITA

KI

iiiiM

iNih

rain

ifiE

liii

* lii

nenn

umni

umum

mum

ursu

nnum

men

inum

umun

nuni

umm

hILI

IIIM

IUM

NIII

IKU

OIS

EC

UU

UM

IMIL

UU

UM

MIC

IUU

UM

MU

MU

LM

IIIM

PAU

MIU

MO

"U11

:11=

2: ''

'''M

11:2

1111

1111

1110

:111

111

-C

ums=

==

szur

nIM

MIN

EIS

I ''ni

eraM

MU

CIA

6111

1111

1104

2:11

1114

119m

9fat

iingp

osup

rje

"11

1111

unit

BIN

llron

eriu

rniiip

h 9r

igllu

miii

iipurii

gmbr

urd

El

MU

din

nil!

L. u

miii

iinin

gaid

inhr

ablh

i1

rhfi

rfilm

illid

iilO

Pus

uo.o

ito. J

imup

pirr

isom

pire

mB

INIM

Mill

iihm

dlirl

irEnl

igh

.1 II

LIP

SP

NIE

RM

INm

e21

::...

3 a

.1 .1

.ag

arsh

elu

igui

nen:

::::::

gib

se E

inse

urik

: :: g

ingn

iona

nuu

;91.

19 ..

......

......

......

......

.....

HIM

_ gr

ilmeg

iriS

PIO

NO

NN

EIE

FOI

Infa

irir

9111

--

9111

"112

1111

1qE

311=

g==

=a1

1.61

1111

0141

1.1.

Rill

iNn

ill.1

.111

1.ff

illi.1

1111

L H

il

-. W

irld

iVila

rinu

oll.

:12

ran=

a:

' 'ja

mm

a L

......

... N

onem

.... m

u H

umor

111

1nu

m'

ii9"-

-1-9

9:11

1111

....q

pr:u

pp9o

gim

umpl

uila

ni"''

' in41

100.

1 11

"44.

1EE

S:::.

.... :

:I:

Ani

es..:

. me

ezE

s....

..

aqua

e-

EIL

IIII

iiiiin

iiiiL

EE

ME

LE

INSI

MM

ingt

hant

ated

attiA

ggill

if.

ESI

NIN

Eff

illiii

iffl

iffi

lliO

NN

IEff

ird

IMPE

ME

N-6

5iEsi

d=ff

ailie

n! ig

hth:

i B

ait e

a fi

iii. r

ejIM

MM

IMM

IIM

IIII

IIM

IIII

MM

UII

IIII

IIII

IMII

IIII

IIIM

IIIM

IIIM

IIII

IIII

NII

IIII

MII

IIM

OIW

IIII

IIII

I..

mou

rmum

mum

umns

eurn

ornu

rallM

1111

11U

UM

UM

BL

IMIU

M:1

2:II

IIH

IMU

IM11

1111

111

Zrn

artir

inM

Illia

mln

"III

IIII

:011

1111

12=

CR

IIII

HW

IMIH

IMII

MU

NC

LIM

IZ".

ow

1111

. 111

1111

1111

1111

1

czcz

ee. .

..enr

arra

nibm

ourn

eem

emor

anee

num

:s--

mum

emun

uenn

innu

nnu

imm

umuu

men

era

:R

uirr

ipm

enir

onnu

rpro

urro

lum

mur

orm

aum

mrr

inus

.911

1111

di i

ndi

IIIE

l ShA

rrin

Un

II E

MU

.ni

theh

imah

lmou

nded

ium

LI-

Ziii

Iiiii

iiiiM

MU

CT

RE

ME

Ntir

Ingi

fira

rdiu

dr:ii

iiiL

iiiiil

ilin

.r...

......

.ISS

INIM

IRFU

ripl

iEse

scap

ii 4

ME

SH H

P: r

i IIg

i sig

tere

paw

ndpa

sq9m

psq1

111

514.

22g:

=:::

: :-:

::::::

. im

-E: :

. =m

ode

...-

1÷,

. ::

. :II

ihr.

sid

: me=

2::.

1:1:

::::.

:::::.

E.

..-.

..-.

, pra

rdm

hom

mom

mou

rs=

inim

umno

mm

ogiu

mm

umm

iroi

mm

onuu

-111

1111

11M

BE

IMIN

IMIE

rse

... ll

llllll

llllll

llllll

llllll

llllll

llllll

llO

ILM

EM

BR

OIN

EIN

IME

NE

EIN

ER

IMIN

NIO

la jr

eaM

IRE

INO

illE

MM

ININ

ION

IEN

EM

INIE

NE

RIE

UN

-111

IM=

_111

1111

I I I I .0 0 S II II'II .11-

I I I I

1]

maza ranummanutunumentummouraullannonmunmun::::::szaz-vmsrpranamunraun2:21rummiumniucaufactivnislmnamiaatannon:::::::::::::::::nummirrarn'MI oounalumnum,:::::16.:=1""INIVIIINIONICRIIIIIII:MINCIll nu,

:::::::::iiiiiMpraiiiiiliPI:Mni:29FERREIragmum!:::::p:::::::::Hrappimi.",",".1lislimolirdilkiligiesibi mitirgsMiAMENEIlhigiiiiii:4511=a1 64==-13=imiiiiiiiiiirniriithilimi

. . iiiirgaiteilliffifiliiiii. EhilliMEMPlilligilii9=iffillilliiiiiM :IMEws.::91:ris:::luarfarrenarassr----miinhowninp1911.....iire-- um:m u!

wa's3 ill dullisgulliffilli:m..1.1SAL... nilitiHinulith:1..: innii. . ,13-- E3=4:..::111-aeldliginigrialipapfigimmg gime - ....1.1.1E5111512

11-41:72,2111111A:P99111 11121"----2::::21.111ktihoimi 1-3P.. . memlinzen.- qr:ffiqffl

g:211 ars VII gli: BF rffl 1 Nil -.----rain::::::::;;Epr.-;:igliEi..::::::REE 1::::::::;sipHilininingiiilintanhardindiffiigh r.:'':an .inniailitiniiiniitidz::::71:2:2A .. 11:::1:Iiihninr ...pi poppul9 .1 sikpani.....pipiriard;;;;Friiiuminrairpuropirm jilt

glom liuniulo iiimull::;:ukupimminiiiiiiiii.qpnommilitup oh. nuunnumn , 11 111111111111111111111 11 IL:1411111111 INN AIM KIIIIIM111111 1M II 1 I

OW= UV= LIN Mil En: :I 411111:221111111:2:::111Ennumiurpommi:;....nagiLl1=1211111111111111131111111rara211111111110 UM WU= g IN HMO= IS IMMO= EI:Billil UT Itt 3 !!!1!!!!!!.22"!!!!InVIIIII"" ToilliMUCI COI ME

Ca:mrInimEransmonnunonsa.....nuanurunnimitmennualacianunummanwmmailinnilammunorillinigninillMillallIMELICIIIIIIMBEHIMIKIIIIMMIN11111111111111 1111

iiPMF--keinairrA, EggEgMrsgili h i MilififflgiP3IRP'- HigrilgignifflneEIralain '671iiiiiimiliiiiiiiitizzililliiiiiimmifilimi.iiillillinfill '11111111:Ndihnulittiigilliiiiiiillitiliiiiiiiiirdlillilliii

..E.,,:.--E........11.1 ammo

BffiffilifileN ra Milintilligz IfillifilEffirsiffil Pilling s=9:41ffli ERE.111

lir InamdmmiaTz2=alaminismitis,.

rifflII

1 1 11111111,11111111111111P i.

!WI 1 i. 11911 mai iiiiii 'I 1111121111111:111111111111 IN 0 HIM MAIM 0111111:11:1111111111111nra NM1111111=1111111261= II IIMM6111111111116=111111111111011011111111..1111111111113811111BERIMENZIOUN=INCEMINIMINIIIIiilinilinil

gliffiffilEll

i-'t IFIUGMEIIIIIII011111111111111111 CIEMI enviii

151WrsiniElfilillININHE EMI ir .. ...

200

100

60

$0

40

30

20

cc

cc

ow 4

X 3

2

ENFE. NMI I

II InMU Mall reanr.Rit tgolimilm.u0::::iiiidu f1

MEE

asIriarinpliirlipirawmarimpriginglinginiqbaroprinquipiri

1 musna: inecram:: 0.: wra. an.MINI ME 1111111E111111111111111111'

=-11THEIMMuillininlini11111121

: I

. . 0,0

A"

--

01

2 13

4;

56

78

9N

01

2'3

--;.

.4

56

78

9

0000

0043

10128

0170 0212

0253

0294

0334

0374

7404

7419

7435

7443

7451

7459

7474

10

0086

55

74:.2

7427

7466

11

(1414

0453

0492

0531

0569 0607

0645

0682

0719

0755

56

7482

749()

7497

7505

7513

7520

7528

7536

7543

7551

12

0792

0828

0864-0899

0934 0969

1001

1038

1072

1106

57

7559

7566

7574

7582

7589

7597

7604

7612

7619

7627

13

1139

1173

1206

1239

1271

1303

1335

1367

1399

1430

58

7634

7642

7649

7057

7664

.7672

7679

76116

7694

7701

14

1461

1492

1523

1553

1584

1614

1644

1673

1703

1732

59

7709

7716

7723

7731

7738

7745

7752

7760

7767

7774

15

1761

1790

1818

1847

1875

1903

1.931

1959

1987

2014

60

7782

7789

7796

7803

7810

7818

7825

7832

7839

7846

16

2041

2068

2095

2122

2148 2175

2201

2227

2253

2279

61

7853

7860

7868

7875

7882

7889

7896

7903

7910

7917

17

2304

2330

2355

2380

2405 2430

2455

2480

2504

2529

62

7924

7931

7938

7945

7952

7959

7966

7973

7980

7987

18

2553

2577

2601

2625

2648 2672

2695

2718

2742

2765

63

7993

8000

8007

8014

8021

8028

8035

8041

8048

8055

19

2788

2810

2833

2856

2878 2900

2923

2945

2967

2989

64

8062

8069

8075

8082

8089

8096

8102

8109

8116

8122

20

3010

3032

3054

3075

3096 3118

3139

3160

3181

3201

65

8129

8136

8142

8149

8156

8162

8169

8176

8182

8189

21

3222

3243

3263

3284

3304 3324

334E,

3365

3385

3404

66

8195

8202

8209

8215

8222

8228

8235

8241

8248

8254

22

3424

3444

3464

3483

3502 3522

3541

3560

3579

3598

67

8261

8267

8274

8280

8287

8293

8299

8306

8312

8319

23

3617

3636,

3655

3674

3692 3711

3729

3747

3766

3784

68

8325

8331

8338

8344

8351

8357

8363

8370

8376

8382

24

3802

3820

3838

3856

3874.3892

3909

3927

3945

3962

69

8388

8395

8401

8407

8414

8420

8426

8432

8439

8445

25

3979

3997

4014

4031

4048'4065

4082

4099

4116

4133

70

8451

8457

8463

8470

8476

8482

8488

8494

8500

8506

26

4150

4166

4183

4200

4216'4232

4249

4265

4281

4298

71

8513

8519

8525

8531

8537

8543

8549

8555

8561

8567

27

4314

4330

4346

4362

4378 4393

4409

4425

4440

4456

72

8573

8579

8585

8591

8597

8603

8609

8615

8621

8627

28

4472

4487

4502

4518

4533 4548

4564

4579

4594

4609

73

8633

8639

8645

8651

8657

8663

8669

8675

8681

8686

29

4624

4639

4654

4659

4683,I

4698

4713

4728

4742

4757

74

8692

8698

8704

8710

8716

8722

8727

8733

8739

8745

30

4771

4786

4800

4814

482914843

4857

4871

4886

4900

75

8751

8756

8762

8768

8774

8779

8785

8791

8797

8802

31

4914

4928

4942

4955

4969 4983

4997

5011

5024

5038

76

8808

8814

8820

8825

8831

8837

8842

8848

8854

8859

32

5051

5065

5079

5092

5105 5119

5132

5145

5159

5172

77

8865

8871

8876

8882

8887

8893

8899

8904

8910

8915

33

5185

5198

5211

5224

5237;5250

5263

5276

5289

5302

78

8921

8927

8932

8938

8943

8949

8954

8960

8965

8971

34

5315

5328

5340

5353

5366:5378

5391

5403

5416

5428

79

8976

8982

8987

8993

8998

9004

9009

9015

9020

9025

35

5441

5453

5465

5478

5490:5502

5514

5527

5539

5551

80

9031

9036

9042

9047

9053

9058

9063

9069

9074

9079

36

5563

5575

5587

5599

5611i5623

5635

5647

5658

5670

81

9085

9090

9096

9101

9106

9112

9117

9122

9128

9133

37

5682

5694

5705

5717

5729'5740

5752

5763

5775

5786

82

9138

9143

9149

9154

9159

9165

9170

9175

9180

9186

38

5798

5809

5821

5832

5843;5855

5866

5877

5888

5899

83

9191

9196

9201

9206

9212

9217

9222

9227

9232

9238

39

5911

5922

5933

5944

595515966

5977

5988

5999

6010

84

9243

9248

9253

9258

9263

9269

9274

9279

9284

9289

40

6021

6031

6042

6053

606416075

6085

6096

6107

6117

85

9294

9299

9304

9309

9315

9320

9325

93309335

9340

41

6128

6138

6149

6160

6170,6180

6191

6201

6212

6222

86

9345

9350

9355

9360

9365

9370

9375

9360

9385

9390

42

6232

6243

6253

6263

6274 6284

6294

6304

6314

6325

87

9395

9400

9405

9410

9415

9420

9425

9430

9435

9440

43

6335

6345

6355

6365

6375 6385

6395

6405

6415

6425

88

9445

9450

9455

9460

9465

9469

9474

9479

9484

8489

44

6435

6444

6454

6464

6474 6484

6493

6503

6513

6522

89

9494

9499

9504

9509

9513

9518

9523

9528

9533

9538

45

6532

6542

6551

6561

657116580

6590

6599

6609

6618

90

9542

9547

9552

9557

9562

9566

9571

9576

9581

9586

46

6628

6637

6646

6656

6665,6675

6684

6693

6702

6712

91

9590

9595

9600

9605

9609

9614

9619

9624

9628

9633

47

6721

6730

6739

6749

6758:6767

6776.6785

6694

6803

92

9638

9643

9647

9652

9657

9661

9666

9671

9675

9680

48

6812

6821

6830

6839

6848.6857

6866

6875

6884

6893

93

9685

9689

9694

9699

9703

9708

9713

9717

9722

9727

49

6902

6911

6920

6928

6937;6946

6955

6964

6972

6981

94

9731

9736

9741

9745

9750

9754

9759

9763

9768

9773

I

50

6990

6998

7007

7016

7021 7033

7012

7050

7059

7067

95

9777

9782

9786

9791

9795

9800

9805

9809

9814

9818

51

7076

7084

7093

7101

7110 7118

7126

7135

7143

7152

96

9823

9827

9832

9836

9841

9845

9850

9854

9859

9863

52

7160

7168

7177

7185

7193 7202

7210

7218

7226

7235

97

9868

9872

9877

9881

9886

9890

9894

9899

9903

9908

53

7243

7251

7259

7267

7275 7284

7292

7300

7308

7316

98

9912

9917

9921

9926

9930

9934

9939

9943

9948

9952

54

7324

7332

7340

7348

7356 7364

7372

7380

7388

7396

99

9956

9961

9965

9969

9974

9978

9983

9987

9991

9996

FIG

UR

E 8

.53a

.Com

mon

Log

arith

ms.

This discussion of logarithms will deal only

with the so-called "common" logarithms which

use a base equal to 10.

First, a definition of a logarithm:

the logarithm of a number N to the

base a is the exponent x or the power

to which the base must be raised to

equal the number N.

In other words:

log N is the logarithm of N to the

base 10

Thus:

if .N = 10x, then x = log N

Further:

log N = characteristic + mantissa

(For instance, log 12.3 = 1 + .0864 = 1.0864)

The mantissa (or decimal part of the logarithm)

is found from the tables of logarithms (Figure

8.53a).

The characteristic is determined in accordance

with two rules:

if the number N is greater than 1, the

characteristic of its logarithm is one

less than the number of digits to the left

of its decimal point

..

.

or

if the number N is less than 1, the

characteristic of its logarithm is neg-

ative; if the first digit which is not

zero is found in the kth decimal place,

the characteristic is -k.

Now, to use logarithms to multiply two numbers,

M and N, find log M and log N:

if N = 10x, then x = log N

if M = 10Y, then y = log M

To multiply M times N:

x + y = log M + log N = log (MN)

When x (the logarithm of N) is added to y (the

logarithm of M), the sum is another logarithm,

the logarithm of M times N.

The antilogarithm

of this value of x plus y is M times N.

Or:

antilog (x +.y) = antilog (log M+ log N)

= M times N

Antilogs are found by using the tables in re-

verse, i.e., enter the tables with a log (not

a number) in order to find a number (not a

log).

FIG

UR

E 8

.53b

.Usi

ng C

omm

on L

ogar

ithm

s.

az.-ra:=Innumaismunan= inum..2..m..jcirMOIEZ1111111 11111 1301111.1111 usEMBUSENNIOEL.-======z

=1222:22MrM

:1.imilm Mal

Imp:.

III

x.7,2m.w.,11ringtirpre"malnwlwanummunt

WOO 111111A111111Thenil=.11:1

::::g11:mYMNma*l"l ee.

'

m

11a"e"

Efing

:in.116, jore

aniarra;

11111221111111111um Ansi no:

=ma :n M I

'"Cull'

"

ird; of pp

RIO IN%nom gn

tlS

1511E191 "NI :116'1

_a zu

1,1-71111

r1 1--/-

amarra=onzonn: mum= ..

mungeounsc :2 CIIIMIIEURILEMEIMRCII. mug ma.... MOClDIIIIIIIMS mono unnumu as Unil : N111111111 111101111:11118:121 ' 11111 ICIIPIIIIMIlanniminnuramonsuoullts inuranummon.....m inunommisma

EIMMF-Effil..4.111VEMEMMEMPAIMMT.MMIIIIIIIIMMILININIFIENMEINIEMBIL911 ---1 LP ITlinflirgit-MilelliffliENvidsierg tig Mg :11.11R: SIT:-- 0.111:::".:ffirdP9 illiElareriltrIgni:94111M1162711111LBI

. d1112.-Muulairegisi-21" Lip om. 2

22::2221Cm °U.1 ZEHMIIIIISMINP:h. 3I I MUM 41 IN= ES ell =MI in O IMENMMI.." OS.

. lllwil;;;;I:1-741--1" '''''''''''''''''''''''''''''''ItunnurriV12.91101 M11111111111 I NNE II^ 111111"11111'

gispyll.aniumroullirOHL MIMMINHOMIIIIMI

. :1..4-41

CHAPTER 9

RADIOLOGICAL MONITORING TECHNIQUES AND OPERATIONS

Consider, for just a moment, what kindof radiological defense could we build if wedid not have radiological monitoring? Itwouldn't be worth much, would it? Radiol-ogical defense is built on facts and radiol-ogical monitoring provides those facts forRADEF decisions and actions. Once anuclear attack is past, this becomes evenmore true with each passing hour for justas, long a time as radiation remains adanger. So if there is a technique in thisbusiness of radiological monitoring (andthere is, very definitely), let's take a lookat it to find out:

HOW

WHENWHAT

WHO

to monitorto monitorto monitorto monitor

WHERE to monitor

(. . . as to WHY to monitor, we havelearned all the reasons for that one quite afew pages back!)

INTRODUCTION

9.1 The data supplied by radiologicalmonitors is the key to RADEF decisionson what to do and how to do it. And in timeof emergency these decisions may be thekey to living or dying. Let's take a closerlook at this vital activity.

WHAT IS RADIOLOGICAL MONITORING?

9.2 Radiological monitoring is definedas the detection and measurement of ra-diation emitted by fallout. With the infor-mation gained through monitoring we can:(1) determine extent and location of fal-lout; (2) validate predictions about fallout;and (3) decide on a course of action.

MONITORING TECHNIQUES 1

9.3 The following paragraphs describethe detailed techniques and procedures forconducting each type of radiological moni-toring activity. Fallout station monitorsare responsible for performing all of themonitoring techniques outlined in this sec-tion. Shelter monitors are responsible forperforming all of the techniques, exceptfOr unsheltered exposure rate measure-ments and unsheltered exposure measure-ments.

SHELTER AREA MONITORING

9.4 Exposure rates should be measuredinside of a shelter or a fallout monitoringstation to determine the best shielded por-tions of the shelter and its immediate ad-joining areas. Procedurv, for this monitor-ing are as follows:

1. Use the CD V-715.2. Check the operability of the instru-

ment.3. Hold the instrument at belt height (3

feet above the ground).4. take readings at selected locations

throughout the shelter and adjoiningareas and record these on a sketch ofthe area.

UNSHELTERED EXPOSURE RATEMEASUREMENTS

9.5 Fallout monitoring stations reportunsheltered exposure rate readings. Pro-cedures for observing unsheltered expo-sure rates are as follows:

1. Use the CD V-715.

' Paragraphs 9,3 through 9.30 are based upon the HANDBOOK FORRADIOLOGICAL MONITORS, FG-E-5.9.

138

135

2. Check the operability of the instru-ment.

3. Take an exposure rate reading at aspecific location in the fallout moni-toring station. This should be done assoon as the exposure rate reaches orexceeds 0.05 R/hr.

4. Go outside immediately to a pre-planned location in a clear, flat area(preferably unpaved), at least 25 feetaway from buildings, and take an out-side reading. The outside readingshould, be taken within three minutesof the 'reading in step 3 above.

5. Calculate. the outside/inside ratio ofthe fallout monitoring station by di-viding the outside exposure rate bythe inside exposure rate. The protec-tion may vary from location to loca-tion within the station. The outside/inside ratio referred to here is appro-priate only for the location where theinside exposure rate measurement isobserved.

6. Multiply future inside exposure ratereadings by the outside/inside ratio atthe selected location to obtain theoutside exposure rate. For example:If the inside reading is 0.5 R/hr andthe outside reading is 80 R/hr, theratio can be found by dividing theoutside reading by the inside reading.Thus, 80 0.5 = an outside/inside ra-tio of 160. If a later inside reading atthe same location in the fallout moni-toring station is 4 R/hr, thus outsideexposure rate can be calculated bymultiplying the ratio by the insidereading. Thus, 160 x 4 = 640 R/hr.

7. Recalculate the outside/inside ratio atleast once every 24 hours during thefirst few days postattack, unless theoutside exposure rate is estimated tobe above. 100 R/hr. This is necessarybecause the energy of gamma radia-tion is changing, thus changing theoutside/inside ratio of the falloutmonitoring station.

8. Record and report the exposure ratemeasurement in accordance with theparticular RADEF organization

136

standard operating procedure. NOTE:It is anticipated that radiation re-ports from the county level of govern-ment upwards would be limited to:a. A flash report immediately upon

measurement of .5 R/hr and in-creasing.

b. A severe radiation report when theradiation level reaches 50 R/hr andincreasing.

c. The highest or radiation peak levelif above 50 R/hr.

d. The time when the decaying expo-sure rate passes downward and be-low 50 R/hr.

e. The time when the radiation leveldecays to .5 R/hr.

9. Take all exposure rate measurementsoutside after the unsheltered expo-sure rate has decreased to 25 R/hr.

9.6 The CD V-717 remote reading in-strument may be used for taking outsideexposure rate measurements. The CD V-717 is used as described below:

1. Position the instrument at a selectedlocation within the fallout monitoringstation.

2. Place the removable ionization cham-ber 3 feet above the ground in a rea-sonably flat area and at least 20 feetfrom the fallout station. Preferablythis should be done prior to falloutarrival. It is desirable to cover theionization chathber with a light plas-tic bag or other lightweight material.

3. Observe outside exposure rates di-rectly.

4. Record and report exposure rates inaccordance with the particularRADEF organization standard opera-ting procedure.

UNSHELTERED EXPOSUREMEASUREMENTS

9.7 Fallout monitoring stations reportunsheltered exposure readings. Proce-dures for taking these readings are listedbelow:

1. Zero a CD V-742.2. Measure the unsheltered exposure

13'3

rate in accordance with paragraph9.5.

3. Select an inside location where theexposure rate is approximately one-tenth to one-twentieth of the unshel-tered exposure rate and position theCD V-742 at this location.

4. Determine the outside/inside ratio forthis location in accordance with theprocedure explained previously.

5. Read the CD V-7.42 daily. If the dailyexposure at this location could exceed200 R, estimate the time required fora 150 R exposure on the CD V-742.Record this reading, rezero the do-simeter, and reposition it. To deter-mine the, daily, unsheltered .exposure,multiply the daily exposure at thislocation by the outside/inside ratio.Record the readings and rezero theinstrument.

0.

PERSONNEL EXPOSURE MEASUREMENTS

9.8 The monitor must determine thedaily exposure of all shelterees or falloutmonitoring station occupants. Proceduresfor determining daily exposures are asfollows:

1. Zero all available CD V-742's.2. Position the dosimeters so that repre-

sentative shelter exposures will bemeasured by the instruments. Themonitor must exercise judgment inpositioning these instruments. Theoutside/inside ratio may vary consid-erably at different locations Withinthe shelter. The instruments shouldbe placed within the areas of greatestoccupancy, which may change withtime. During the early high radiationperiod, occupancy will be concen-trated in the high protection areas ofthe shelter. Later, the occupancy ofthe shelter can be expanded. If repre-sentative readings are to be obtained,the dosimeters must follow the loca-tion shifts of the occupants.

3. If several dosimeters are positionedin one compartment, read the dosime-ters each day and average the totalexposures. Recharge dosimeters

RADIATION EXPOSURE RECORD

Name tretrirst4 LICEAddress 2-27 N bloc R,^040

'13.-NrrLE Ceir.isK folIC f-

Soc Sec No 5 4",- ' Ir.t. -3" c3rDate(s) Total Exposure

f toExpoosure(s) Dally Dat e

4, /4Lt...:a /.5- / 5-C /7 /LL 5- 1cJ, we -I _LS" 1 r6 - V -"CY!? -1 cc.:

DOD FORM DATE

FRONT SIDE

Date(s)of

Exposure(s)Daily

Exposare(s)

Total Exposureto

Date

I_I_ I

BACK SIDE

FIGURE 9.8.Radiation exposure record.

which read more than half scale. Ifsome shelters are divided into com-partments or rooms that may havedifferent outside/inside ratios, the ex-posure should be measured or calcu-lated for each compartment.

4. Instruct the shelter occupants to re-cord their individual exposures ontheir radiation exposure record (Fig-ure 9.8), as approved by the sheltermanager. Exposure entries should bemade to the nearest roentgen. Con-tinue to read the dosimeters eachday. Record the accumulated expo-sure, if measurable.

9.9 If monitors or other persons arerequired to go outside, these additionalexposures should be measured and re-corded.

PERSONNEL MONITORING

9.10 The present DCPA concept is thatany amount of contamination remainingon clothing after brushing and shaking asa countermeasure would be insignificantas a health hazard.

FOOD AND WATER MONITORING

9.11 Food and water monitoring crite-ria and techniques are being reevaluated,and are subject to change. During an earlyfallout condition, the radiation level is

I ti o

137

likely to be above the range of the CD V-700 and, in effect, render it unsuitable fordetermining whether food and water sup-plies are acceptable for human consump-tion.

9.12 Since radiation passing throughfood does not contaminate it, the only dan-ger would be the actual swallowing of fal-lout particles that happen to be on or inthe food itself (or on the can or packagecontaining the food). Fallout particlesshould be wiped or washed off. Reapingthreshing, canning and other processingwould prevent dangerous quantities of fal-lout from getting into most processedfoods. It is believed that ordinary precau-tions, normally taken in preparing foods toeat, would keep radiological contaminationwithin acceptable limitations.

9.13 Water systems, might be affectedby radioactive fallout, buts the risk wouldbe small. Water stored in covered con-tainers, or in covered wells would not becontaminated after an attack. Even in un-covered containers, indoors, such as buck-ets or bathtubs filled with emergency sup-plies of water, it is highly unlikely that thewater would be contaminated by falloutparticles. Practically all of the fallout par-ticles that drop into open reservoirs, lakes,and streams would settle to the bottom.

9.14 Do not discard food and waterknown, or suspected to be contaminated.It should be placed in storage and usedwhen other less contaminated food is notlonger available. If only contaminatedfood or water is available use supplies withthe smallest amount of contaminationfirst.

AREA (MOBILE) MONITORING

9.15 Area monitoring is used to locatezones of contamination and determine theexposure rates within these zones. Themonitor should be informed by his Radiol-ogical Defense Officer concerning routesto be followed, locations where readingsare needed, the mission exposure, and theestimated time needed to accomplish themission.

9.16 First, plan to keep personnel expo-sures as low as possible:

138

1. Know the specific accomplishment,extent, and importance of each moni-toring mission.

2. Know the allowable exposure for eachmission and the expected exposurerates to be encountered.

3. Make allowances for the exposure tobe received traveling to and from themonitoring area. Obtain informationabout the condition of roads, bridges,etc., that might interfere with themission and lengthen exposure time.

9.17 Next, consider the clothing whichwill be needed for the mission.

1. Tie pants cuffs over boots or leggings.2. When dusty conditions prevail, wear

a protective mask, gloves, head cover-ing, and sufficient, clothing to coverskin areas. If no masks are available,'cover the nose and mouth with ahandkerchief.

9.18 Very important, of course, is theequipment needed for the missi

1. Use the CD V-715. If the exposurerates are expected to be below 50 mR/hr_ also carry the CD V-700.

2. Wear a CD V-742.3. Carry contamination signs, if areas

are to be marked. This may also re-quire stakes, heavy cord, hammer andnails for posting the signs.

4. Carry a pencil, paper, and a map withmonitoring points marked.

3.19 The procedures for area monitor-ing are as follows:

1. Zero the dosimeter before leavingthe shelter and place it in a pocket toprotect it from possible contamina-tion.

2. Check the operability of the CD V-715 and CD V-700, if it is to be used.

3. Use vehicles such as autos, trucks,bicycles, or motorcycles when dis-tances are too great to cover quicklyon foot. Keep auto and truck cab win-dows and vents closed when travelingunder extremely dusty conditions.The use of a bicycle or motorcyclemay be more practical if roadwaysare blocked.

4. Take readings at about three feet

141

(belt high) above the ground. If read;ings are taken from a moving vehi-cle, the instrument should be posi-tioned on the seat beside the driver.If readings are to be taken outside avehicle, the monitor should moveseveral feet away from the vehicle totake the reading.

5. Record the exposure rate, the timeand loCation for each reading. Ifreadings are taken within a vehicle,this should be noted in the report.

6. Post markers, if required by the mis-sion. The marker should face awayfrom the restricted area. Write thedate, time, and exposure rate on theback of the marker.

7. Read the pocket dosimeter at fre-quent intervals to determine whenreturn to shelter should begin. Al-lowances should be made for the ex-posure to be received during returnto the shelter.

8. Remove outer clothing on return tothe shelter and visually check allpersonnel for contamination.

9. Decontaminate, if required.10. Report results of the survey.11. Record radiation exposure (see Fig-

ure 9.8).

EXPOSURE RATE READINGS FROMDOSIMETERS

9.20 Survey instruments should alwaysbe used to measure exposure rates. How-ever, if no operable survey instrumentsare available, dosimeters can be used tocalculate exposure rates by following thesteps listed below.

1. Zero a CD V-742.2. Place the zeroed dosimeter at a se-

lected location.3. Expose the dosimeter for a measured

interval of time, but do not remain inthe radiation field while the dosime-ter is being exposed. This intervalshould be sufficient to allow the do-simeter to read at least 10 R. It maytake one or two trials before theproper interval can be selected.

4. Read the dosimeter.

5. Divide sixty minutes by the numberof minutes the dosimeter was ex-posed. Multiply this number by themeasured exposure. Example: If theexposure is 10 R for a measured inter-val of five minutes, the rate can becalculated as follows:

(60 ÷ 5) x 10 = 12 x 10= 120 R/hr.,

MONITORING OPERATIONS

9.21 .Radiological monitors, whether as-signed to community shelters or falloutmonitoring stations, perform essentiallysimilar operations. Any departures fromthe operations described here will be theresult of decisions by State and local orga-nizations and must be reflected in theirstandard operating procedures. If local orState standard operating procedures arenot in existence, monitors should followthe procedures outlined in the followingparagraphs.

READINESS OPERATIONS

9.22 During peacetime, all assignedmonitors should:

1. Participate in refresher training ex-ercises and tests as scheduled tomaintain an organized monitoring ca-pability.

2. Prepare- a sketch of the monitoringstation or shelter and adjoining areasfor use during shelter occupancy.

3. Plan a location in the shelter in coor-dination with the shelter manager toserve as the center of monitoring op-erations.

4. Make all' operational sets availableonce every two years to the Statemaintenance shop for recalibration,repairs if necessary, and new batter-ies.

SHELTER OPERATIONS

9.23 Upon attack or warning of attack,a shelter monitor reports to the sheltermanager in his assigned shelter and per-forms the following CHECK LIST of oper-ations in order:

1. Perform an operational check on allsurvey meters.

142139

2. Charge dosimeters.3, Position dosimeters at predesig-

nateci locations in the shelter.4. Report to the shelter manager on

the conditions of the instrumentsand the positioning of dosimeters.

5. Check to see the doors, windows, orother openings are closed during fal-lout deposition.

6. Begin outside monitoring to deter-mine the time of fallout arrival. Ad-vise the shelter manager when therate begins to increase.

7. Insure that all persons who haveperformed outside missions in con-taminated areas, follow the protec-tive actions indicated.

8. Food and water stored in the sheltershould be acceptable for consump-tion. Leave contaminated items out-side the shelter or place them inisolated storage near the shelter.

9. Take readings at selected locationsthroughout the shelter and recordthe exposure rates on preparedsketches of the area. Particular at-tention should be given to monitor-ing any occupied areas close to fil-ters in the ventilating system.. Showthe time of readings on all sketches.

10. Furnish all sketches to the sheltermanager and recommend one of thefollowing courses of action:a. If exposure rates are not uniform,

occupy the areas with lowest ex-posure rates.

b. If space prohibits locating allshelterees in the better protectedareas, rotate personnel to distrib-ute exposure evenly. Do not ro-tate personnel unless there is asignificant difference in the expo-sure between the best and theleast protected shelter occupants.

11. Repeat the above procedure at leastonce daily. If there is a rapidchangein the exposure rate, repeat at leastonce every six hours.

12. Inform the shelter manager to no-tify the appropriate emergency oper-ating center and request guidance if:

140

a. The inside exposure rate reachesor exceeds 10 R/hr at any timeduring the shelter period. .

b. The calculated exposure will ex-ceed 75 R within any two days pe-riod of shelter.

13. Issue each shelter occupant a Radia-tion Exposure Record. As approvedby the shelter manager, advise eachperson once daily of their exposureduring the previous 24 hours. Followprocedures in paragraph 9.8 to calcu-late exposure of shelter occupants.

9.24 During the latter part of the shel-ter period, when there is a less frequentneed for in-shelter monitoring, some of theshelter monitors may be required to pro-vide monitoring services in support ofother emergency operations. A monitoringcapability should always be retained inthe shelter until the end of the shelterperiod.

9.25 At the conclusion of the shelterperiod, all shelter monitors, except thoseregularly assigned to emergency services,may expect reassignment.

FALLOUT MONITORING STATIONOPERATIONS

9.26 For his own protection and thepvotection.of all members of a fallout mon-itoring station, the monitor should per-form the same shelter operations as de-scribed in paragraph 9.23. In addition, thefallout station monitor will measure, re-cord, and report unsheltered exposure andexposure rates to the appropriate EOC.Unless otherwise specified by the 'localstandard operating procedure, the monitorwill:

1. Make a FLASH REPORT when theoutside exposure rate reaches or ex-ceeds 0.5 R/hr.

2. Record and report exposure and expo-sure rates in accordance with localreporting requirements.

MONITORING IN SUPPORT OFEMERGENCY OPERATIONS

9.27 As soon as radiation levels de-crease sufficiently to permit high priority

143

operations and later, as operational recov-ery activities including decontaminationof vital areas and structures are begun,,allfallout station monitors and most commu-nity shelter monitors are required to pro-vide radiological monitoring support tothese operations. Radiological Defense Of-ficers will direct the systematic monitor-ing of areas, routes, equipment and facili-ties to determine the extent of contamina-tion. This information will help the CivilPreparedness organization determinewhen people may leave shelter, whatareas may be occupied, what routes maybe used, and what areas and facilitieSmust be decontaminated.

9.28 Many government services person-nel, such as fire, police, health, and wel-fare personnel, will serve as shelter moni-tors or fallout station monitors during theshelter period.-However, as operational're-covery activities are begun, they will haveprimary responsibility in their own fields,with secondary responsibilities in radiol-ogical defense. Most services will providefor a radiological monitoring capability forthe protection of their operational crewsperforming emergency activities. The ca-pability is provided until the RadiologicalDefense Officer determines that it is notrequired. Services provide this capabilityfrom their own ranks, to the extent practi-cal, supported by shelter monitors and fal-lout station monitors, when required.

9.29 When a service is directed to per-form a mission, the emergency operatingcenter furnishes the following informa-tion:

1. The time when the service may leaveshelter to perform its mission.

2. The allowable exposure for the com-plete mission; that is, from time ofdeparture until return to shelter.

3.. The exposure rate to be expected inthe area of the mission.

9.30 The monitor supporting emer-gency operations will:

1. Read his instruments frequently dur-ing each operation and advise the in-dividual in charge of the mission onnecessary radiological protectivemeasures and when the crew mustleave the area and return to shelterto avoid exceeding the planned mis-sion exposure.

2. Determine the effectiveness of decon-tamination measures, if supportingdecontaminb:an operations.

3. Monitor equipment on return to shel-ter, or base of operatibns, to deter-mine if it is contaminated, and if so,direct decontamination of that equip-ment.

4. Advise the crew on personnel decon-tamination if necessary.

14 4

141

CHAPTER 10

PROTECTION FROM RADIATION

Different forms of protection from nu-clear radiation are available to us. Some ofthese are all right, some are excellent andsome are poor.

We need information on these forms ofprotection and this chapter will give usthat information. We will see:

HOW time can provide protectionHOW distance can provide protec-

tionHOW shielding can provide protec-

tionWHAT makes a shelter

WHAT else is necessary

INTRODUCTION

10.1 As we have seen in previous chap-ters, the residual nuclear radiation fromfallout presents a number of difficult andinvolved problems. This is so not only be-cause the radiations are invisible, and re-quire special instruments for their detec-tion and measurement, but also because ofthe widespread and long lasting characterof the fallout. In the event of a surfaceburst of a high yield nuclear weapon, thearea contaminated by the fallout could beexpected to extend well beyond that inwhich casualties result from blast, ther-mal radiation, and the initial nuclear ra-diation. Further, whereas the other effectsof a nuclear explosion are over in a fewseconds, the residual radiation persists fora considerable time.

10.2 In Chapter 6 we learned that ra-dioactive material released by a nuclearexplosion consists of: (1) radioactive parti-cles created by the fissioning of the bombmaterial, (2) particles made radioactive byneutrons released at the time of explosion,

142

ALPHA ARTICLES TRAVEL ONLYAIOUT AN INCH IN AIR ANDARE STOPPED IV A SHEET OFPAPER OR THE SKIN TISSUE

IETAPARTICLES TRAVEL A FEW FEET IN AIRAND ARE STOPPED SY AN INCH OFWOOD OR A THIN SHEET OF ALUMINUM

GAMMARAYS TRAVEL HUN.DREDS OF FEET INAIR AND ARE REDUCEDIV THICK LEAD ORCONCRETE

01,:4.0.0°

FIGURE 10.2.Three kinds of nuclear radiation.

(3) the unfissioned material of the bombitself. The unfissioned material is gener-ally alpha emitting, while the fission prod-ucts and the neutron-induced radioactiveisotopes are beta-gamma emitters. SeeFigure 10.2 to refresh your memory aboutthe penetrating power of the 3 major kindsof radiation.

PROTECTION FROMEXTERNAL RADIATION

10.3 To protect against external radia-tion, (basically gamma rays), there arethree things you can put between you andthe fallout causing the radiation: TIME,DISTANCE, AND A SHIELD. Protectionis provided by: (1) controlling the length oftime of exposure; (2) controlling the dis-tance between the body and the source ofradiation; and (3) placing an absorbingmaterial between the body and the sourceof radiation.

10.4 It is not generally possible to useonly one factor of protection. The factor oftime is always involved, that is, time isusually used in combination with distance.,

145

shielding, or both. For comparison, con-sider the problem of protecting the eyesfrom ultraviolet rays when taking a sun-bath. Ultraviolet rays may be harmful tothe eyes. A certain amount can be toler-ated, but beyond this point damage maybe caused. The eyes can be protected inthree ways. First is to regulate the timespent under the sunlamp. Second is toregulate the distance maintained betweenthe eyes and the sunlamp, Third is toshield the eyes with sunglasses. The den-ser the glasses, the more ultraviolet raysare filtered out and therefore an individ-ual can be closer to the lamp and staythere a longer pe .iod of time without hurt-ing his eyes. In order to understand eachof the three factors of protection, it isnecessary to discuss them separately.

TIME

10.5 For simplicity, let us disregard thedecay of the radioactive materials in fal-lout and assume that we are in an areawhere the exposure rate remains constantat 25 R/hr. In one hour, we would beexposed to 25 roentgens of radiation. If westayed 2 hours, we would be exposed to 50R. If we stayed 4 hours, our exposurewould be 100 R, and for an 8 hour stay wewould receive an exposure of 200 R. Thus,time could be used as a protective measureby keeping the period of exposure down toan absolute minimum. For instance, ifwork must be done in a high radiationarea, the work should be carefully plannedto minimize the stay time in the con-taminated area.

10.6 As discussed in Chapter 8, the de-cay of radioactive materials will cause theradiation levels from fallout to decreasewith time. In the early periods after deto-nation, the decrease in exposure rates isvery rapid. At later times, the decrease isnot as rapid because the longer lived fis-sion products make the major contributionto the exposure rate. Knowledge of thegeneral decay pattern of radioactive fal-lout suggests an additional way in whichtime is important. All work in contami-nated areas shoulthbe postponed as longas practicable after the detonation of nu-

clear weapons in order to permit radiationlevels to decrease. It should be remem-bered, however, that-it.js..possible for ra-diation levels to increase after long pe-riods of decreasing exposure rates, be-cause of the deposition of additional fal-lout.

DISTANCE

10.7 The effect of distance from a fal-lout field is sometimes misunderstood.When the distances are large in relation tothe size of the radioactive source, the ex-posure rates decrease by the square of thedistance from the source. This "inversesquare law" can. be an effective protectivemeasure when using the sealed sources(sometimes called point sources) in aDCPA Training Source Set. However, in afallout field, which consists of billions of"point sources" spread over large areas,the inverse square law is of no value to aRADEF Officer in computing the decreasein exposure rates with distance from con-taminated areas.

10.8 The fact that exposure rates dodecrease with distance from a fallout fieldwill be very important to us, however,when We discuss the protective features oflarge _buildings later in this chapter. Dis-tance is also important to the RADEFOfficer when he considers the use of decon-tamination as a radiological countermeas-ure. An area called a buffer zone is us-ually decontaminated around a vital facil-ity to increase the distance of the falloutfield from the facility. The function of thebuffer zone is to reduce the gamma expo-sure rate which originates in the sur-rounding unreclaimed area.

SHIELDING

10.9 You will recall that the damagingeffects of gamma rays comes from the factthat the rays strike electrons in the bodyand knock them out of their orbit, and ifthis happens to sufficient electrons in thebody, radiation injury occurs. If we wish tostop a high proportion of the rays beforethey get to us, we can place between our-selves and thesource of the radiation amaterial which has a lot of electrons in its

I 4 6143

makeup. The more electrons there are inthe makeup of the material the more ra-diation will be stopped.

10.10 Figure 10.10 shows lead andwater in a rough comparison of theiratomic makeup. Since lead has a lot moreelectrons in the orbits of each atom thandoes water, lead makes a better shieldthan water.

10.11 Figure 10.11 shows the relativeefficiency of various shielding materials.These materials are efficient in about theproportions shown on the chart in stop-ping the same amount of gamma. Variousshielding materials are used in variousapplications, depending upon the purposeto be served. Lead, for instance, is quitecompact and is most suitable where spacerequirements are a factor. On the otherhand, water is used where it is necessaryto see through the shielding material andto work through it with a long-handledtool to perforM necessary operations, suchas, in processes in atomic plants wheresawing or cutting the radioactive mate-rials is necessary.

10.12 When considering fallout shel-ters, protection is generally achieved intwo ways. One method is to place a barrierbetween the fallout field and the individ-

LEAD

STEEL

0cko. a a 4,q 4'1 CONCRETE

EARTH

WATER

FIGURE 10.11.Relative efficiency of variousshielding materials.

1 44

WOOD

WATER

FIGURE 10-10.--Comparison between lead atom andwater molecule.

ual. This is termed "barrier shielding."The second method is to increase the dig:tance of the individual from the falloutfield contributing to the individual's expo-sure. This is termed "geometry shielding."

10.13 In most analyses it is necessaryto consider the effects of both barrier andgeometry shielding. This is termed "com-bined shielding."

10.14 The heavier the barrier betweenfallout and the individual,, the grdater thebarrier shielding effect. Examples of bar-riers in structures are walls, floors, andceilings.

10.15 Geometry shielding is determinedby the extent of the fallout field affectingan individual, and/or his distance from it.Consider an example of geometry shield-ing.

10.16 If two buildings are of the sameheight and similar construction, but ofdifferent area, the protection from groundcontamination would be- greater on thefirst floor in the building with the largerarea. On the other hand, if two buildingsare of equal area and similar construction,but differ in height, protection fromground contamination would be greater onthe upper floor of the higher building.

THE SHELTER PROTECTION FACTOR

10.17 The effects of geometry shieldingand barrier shielding are combined into aterm very useful for considering the effec-tiveness of various types of shelters. Thiscombined term is THE PROTECTION

FACTOR. One definition is: a calculationof the relative reduction in the amount ofradiation that would be received by a per-son in a protected location, compared tothe amount he would receive if he wereunprotected in the same location. (SeeGlossary for the difference between out-side/inside ratio and protection factor.)

10.18 if a shelter has a protection fac-tor of 100, an unprotected person at thesame location would be exposed to 100times more radiation than someone insidethe shelter.

10.19 Where conditions are favorable,added protection can be had for little extracost. While licensed public shelters have aminimum of PF 40, a higher degree ofprotection up to say 1,000 is advantageous.This will frequently be possible in buildingprotection into new structures.

10.20 There are two ways to go aboutsetting up adequate shelters: COMMU-NITY ACTION and FAMILY ACTION. Itshould be stressed that they are not mu-tually exclusive. In fact, they supplementeach other in a very necessary way. Mostpeople spend the largest part of their timeat or near their homes and there arestrong sociological advantages to keepingfamily groups together in a time of crisisand hardship. However, for many people itis not practical to construct home shelters.And, even if one possesses the finest shel-ter in the world, it will do no good if he iscaught away from home at a time of dan-gerous fallout.

PUBLIC SHELTERS

10.21 Further, experience in Europe inWorld War II and other human experi-ences under disaster conditions havepointed to distinct advantages of the pub-lic shelter when compared with the familyshelter. There are several reasons whygroup shelters are preferable in many cir-cumstances:

1. A larger than family-size group prob-ably would be better prepared to facea nuclear attack than a single family,particularly if some members shouldbe away from home at the time ofattack.

FIGURE 10.22.Group sheltering in a large buildir9-.

2. There would be more opportunity tofind first aid and other emergencyskills in a group, and the risk of radia-tion exposure after an attack could bemore widely shared.

3. Community shelters would provideshelter for persons away from theirhomes at the time of an attack.

4. Group shelters could serve as a focusfor integrated community recoveryactivities in a postattack period.

5. Group shelters could serve other coni-munity purposes, as well as offer pro-tection from fallout following an at-tack.

10.22 These are the reasons why theFederal Government has been involvedwith a number of activitiesinvolvingguidance, technical assistance, andmoneyto encourage the development of .

public shelters. The overall program,which got underway with the National

148145

Shelter Survey, aims at securing sheltersin existing and new structures, markingthem, and making them available to thepublic in an emergency. Where there arenot enough public shelters to accommo-date all citizens, efforts are being made toprovide more. In some cases, such as inlarge cities, it may not be possible to buildindividual family fallout shelters. Groupshelters such as illustrated in Figure 10.22may be required to provide adequate pro-tection in such situations.

FAMILY SHELTERS

*A .Holne Shelter May Save Your Life10.23 Even though public fallout shel-

ters usually offer many advantages overhome shelters, in many placesespeciallysuburban and rural areasthere are fewpublic shelters. If there is none near you, ahome fallout shelter may save your life.

10.24 The basements of some homesare usable as family fallout shelters asthey now stand, without any alterations orchangesespecially if the house has twoor more stories, and its basement is belowground level.

10.25 However, most home basementswould need some improvements in order to

11 11E 10.24.Home basement.

'Paragraphs 1 0.23 through 10.57 arc from the Ia 'PA publication "InTime of Emergency," March Hiatt.

1 46

shield their occupants adequately fromthe radiation given off by fallout particles.Usually, householders can make these im-provenents themselves, with moderate ef-fort and at low cost. Millions of homeshave been surveyed for the Defense CivilPreparedness Agency (DCPA) by the U. S.Census Bureau, and these householdershave received information on how much-fallout protection their basements wouldprovide, and how to improve this' protec-tion.

Shielding Material Is Required10.26 In setting up any home fallout

shelter, the basic aim is to place enough"shielding material" between the people inthe shelter and the fallout particles out-side.

10.27 Shielding material is any sub-stancerthat would absorb and deflect theinvisible rays given off by fallout particlesoutside the house, and thus reduce theamount of radiation reaching the occu-pants of the shelter: The thicker or denserthe shielding material is, the more itwould protect the shelter occupants.

10.28 Some radiation protection is pro-vided by the existing, standard walls andceiling of a basement. But if they are notthick or dense enough, other shielding ma-terial will have to be added.

10.29 Concrete, bricks, earth and sandare some of the materials that are denseor heavy enough to provide fallout protec-tion, For comparative purposes, 4 inches ofconcrete would provide the same shieldingdensity as:

5 to 6 inches of bricks.6 inches of sand or gravel.

(May be packed into bags, cartons,boxes, or other containers for easierhandling.)

7 inches of earth.8 inches of hollow concrete blocks (6

inches if filled with sand).10 inches of water.

14 inches of books or magazines.18 inches of wood.

How to Prepare a Hont'.e Shelter10.30 If there is no public fallout shel-

ter near your home, or if you would prefer

to use a family-type shelter in a time ofattack, you should prepare a home falloutshelter. Here is how to do it:

10.31 A PERMANENT BASEMENTSHELTER. If your home basementorone corner of itis below ground level,your best and easiest action would be toprepare a permanent-type family shelterthere. The required shielding materialwould cost perhaps $100-$200, and if youhave basic carpentry or masonry skills youprobably could do the work yourself in ashort time.

10.32 Here are three methods of provid-ing a permanent family shelter in the"best" corner of your home basementthat is, the corner which is most belowground level.

Ceiling Modification Plan A10.33 If nearly all your basement is

below ground level, you can use this planto build a fallout shelter area in one cor-ner of it, without changing the appearance

flotanumas-oVintelatingea

of it or interfering with its normal peace-time use.

10.34 However, if 12 inches or more ofthe basement wall is above ground level,this plan should not be used unless youadd the "optional walls" shown in thesketch.

10.35 Overhead protection is obtainedby screwing plywood sheets securely tothe ,joists, and then filling the spaces be-tween the joists, with bricks or concreteblocks. An extra beam and a screwjackcolumn may be needed to support the ex-tra weight.

10.36 Building this shelter requiressome basic woodworking skills and about$150-$200 for materials. It can be set upwhile the house is being built, or after-ward.

Alternate Ceiling Modification. Plan B10.37 This is similar to Plan A except

that new extra joists are fitted into part ofthe basement ceiling to support the added

FAMINIVARMINIONINETITF°'

ki/V1g1111111

r velum sit:7----!!"31

011111rigit

NI lolls

Ii)i 111

\I

Hi!

I, \

?11

1111W.,1111111.111.2;

4041660,;_\1

ONIPM111

.:111111111101111111111111111

a:11111111110i44111111.11111l.lathitutYpvicsuclumt

Iiim,1010111110fixitC1111111

01111.tlifiatilit41114Pr..,,,r,...L,iI

......

FIGURE 10.31.Permanent basement shelter.

115 U

147

IWZAWE

IM iziiIlik11111

bricks or blocks

IMPVIMlow

ts LI

screwjackcolumn

041140 1%1

IMEINIMOMM/AMF ;14041/41mmessimmunsmarg 5EIPA0111rairommem.00 gril jmili! giummimmoss....r00;:

Nom AMEN MI 01 5.1 ilivillRI. miti::paii.,,

cu. '''Pgawinvilxiir;Atli--IKv.1isrel.m:fainowFl row! -1,

Illrip., Jimuommi41,_ .,_,..,..

,magytENNA

NEWJOISTS

optional walls

existing joists

beam

concrete blockor brick

screwjack column

FIGURE 10.33.Ceiling modification plan A.

EXISTINGJOISTS

i=' I

saiL:

i

AhVAtWX4NIM lel

l- NIVI0o0till1011Nom.. smammsTpow 0 01_,,,ta

am mrimm. =I 1.1. Nim a /OW VI imom. rniii. .= =IN W01.04111..--/limp

11)

o.0100 31[1I l'*111.111111MINLIIMMIUMINIMMIN

museumMIR

avaliku"

half basement

_11111111111111111111h.

ceiling width

.441.00111111111k

*fro-1,61,0

in1111111Nii11.11101.

FIGURE 10.37.Alteate ceiling modification Plan B.

weight of the shielding Cinf..tead of using abeam and a sCrewjack column).

10.38 The new wooden joists are cut tolength and notched at the ends, then in-stalled between the existing joists.

148

half basementceiling length

10.39 After plywood panels are screwedsecurely to the joists, bricks or concreteblocks are then packed tightly into thespaces between the joists. The bricks orblocks, as well as the joists themselves,

151

will reduce the amount of fallout radiationpenetrating downward into the basement.

10.40 Approximately one-quarter of thetotal basement ceiling should be rein-forced with extra joists and shielding. ma-te rial.

10.41 Important: This plan (like PlanA) should not be used if 12 inches or moreof your basement wall is above groundlevel, unless you add the "optional walls"inside your basement that are shown inthe Han A sketch.

Permome)a Concrete Block or Brick Shel-ter Plan C

10.42 This shelter will provide excellentprotection, and coin be constructed easily

at a cost of $150 in most parts of thecountry.

10.43 Made of concrete blocks or bricks,the shelter should be located in the cornerof your basement that is most belowground level. It can be built low, to serveas a "sitdown" shelter; or by making ithigher you can have a shelter in whichpeople can stand erect.

10.44 The shelter ceiling., however,should not be higher than the outsideground level of the basement corner wherethe shelter is located.

10.45 The higher your basement isabove ground level, the thicker you shouldmake the walls and roof of this shelter,

I

af# ill° 9... 11111Wi 1111110CIA0 0

1111111..1.111Li*Illial.f.1117;1111:1111111111001.11WIIIII-'..611.11:111.111111:111;1:11111.1101.1111111.1111.14111.1

7711.11111111rolOnWOW-0.110101110.01 011.01-amill .00

Place entranceway onside or end not facingexposed basement wall

Increase thickness of shelter wallfacing exposed basement wall byfour inches

FIGURE 10,12.Permanent concrete block or brick shelter plan C.

1 49

152

FIGURE 10.49. Preplanned snack bar shelter plan D.

since your regular basement walls willprovide only limited shielding against out-side radiation.

10.46 Natural ventilation is providedby the shelter entrance, and by the airvents shown in the shelter wall.

10.47 This shelter can be used as astorage room or for other useful purposesin non-emergency periods.

A Preplanned Basement Shelter10.48 If your home has a basement but

you do not wish to set up a permanent-type basement shelter, the next best thing

would be to arrange to assemble a "pre-planned" home shelter. This simply meansgathering together, in advance, the shield-ing material you would need to make yourbasement (or one part of it) resistant tofallout radiation. This material could bestored in or around your home, ready foruse whenever you decided to set up yourbasement shelter. Here are two kinds ofpreplanned basement shelters.

Preplanned Snack Bar Shelter Plan D10.49- This is a snack bar built of bricks

or concrete blocks, set in mortar, in the

150

FIGURE 10.51.Preplanned tilt-up storage unit plan E

1 r

"best" corner of your basement (the cor-ner that is most below ground level). Itcan be converted quickly into a falloutshelter by lowering a strong, hinged "falseceiling" so that it rests on the snack bar.

10.50 When the false ceiling is loweredinto place in a time of emergency, thehollow sections of it can be filled withbricks or concrete blocks. These can bestored conveniently nearby, or can be usedas room dividers or recreation room furni-ture (see bench in Figure 10.49).

Preplanned Tilt-Up Storage Unit Plan E10.51 A tilt-up storage unit in the best

corner of your basement is anothermethod of setting up a "preplanned" fam-ily fallout shelter.

10.52 The top of the storage unit shouldbe hinged to the wall. In peacetime, theunit can be used as a bookcase, pantry, orstorage facility.

10.53 In a time of emergency, the stor-age unit can be tilted so that the bottom ofit rests on a wall of bricks or concreteblocks that you have stored nearby.

10.54 Other bricks or blocks shouldthen be placed in the storage unit's com-partments, to provide an overhead shieldagainst fallout radiation.

FIGURE 10.56.Covering basement windows

10.55 The fallout protection offered byyour home basement also can be increasedby adding shielding material to the out-side, exposed portion of your basementwalls, and by covering your basement win-dows with shielding material.

10.56 You can cover the abovegroundportion of the basement walls with earth,sand, bricks, concrete blocks, stones fromyour patio, or other material.

10.57 You also can use any of thesesubstances to block basement windowsand thus prevent outside fallout radiationfrom entering your basement in that man-ner.

INDIVIDUAL PROTECTIVE MEASURES

10.58 If the presence of fallout is sus-pected before an individual can reach shel-ter, the following actions will help mini-mize its effects.

1. Cover the head with a hat, or a pieceof cloth or newspaper.

2. Keep all outer clothing buttoned orzipped. Adjust clothing to cover asmuch exposed skin as possible.

3. Brush outer clothing periodically.4. Continue to destination as rapidly as

practicable.10.59 Assume that all persons arriving

at a shelter or a fallout monitoring stationafter fallout arrival, and all individualswho have performed outside missions arecontaminated. All persons should followthe protective measures below:

1. Brush shoes, and shake or brushclothing to remove contamination.This should be done before enteringthe shelter area.

2. Remove and store all outer clothingin an isolated location.

3. Wash, brush, or wipe thoroughly, con-taminated portions of the skin andhair being careful not to injure theskin.

COLLECTIVE PROTECTION

10.60 During fallout deposition, all win-dows, doors, and nonvital vents in shel-tered locations should be closed to control

154151

the contamination entering the shelter.Similar protective measures should be ap-plied to vehicles.

10.61 When radiation levels becomemeasurable inside the shelter, make a sur-vey of all shelter areas to determine thebest protected locations. Repeat this pro-cedure periodically. This information isused to limit the exposure of shelter occu-pants.

TASKS OUTSIDE OF SHELTER

10.62 When personnel leave shelter ap-propriate protective measures should betaken to prevent the contamination oftheir bodies. Clothing will not protect per-sonnel from gamma radiation, but will pre-vent most airborne contamination fromdepositing on the skin. Most clothing issatisfactory, however, loosely woven cloth-ing should be avoided. Instruct shelteroccupants to:

1. Keep time outside of shelter to a mini-mum when exposure rates are high.

2. Wear adequate clothing and cover asmuch of the body as practical. Wearboots or rubber galoshes, if available.Tie pants, cuffs over them to avoidpossible contamination of feet and an-kles.

3. Avoid highly contaminated areaswhenever possible. Puddles and verydusty areas where contamination ismore probable should also be avoided.

4. Under dry and dusty conditions, donot stir up dust unnecessarily. Ifdusty conditions prevail, a man'shankerchief or a folded piece ofclosely woven cloth should be wornover the nose and mouth to keep theinhalation of fallout to a minimum.

152

15 5

5. Avoid unnecessary contact with con-taminated surfaces such as buildingsand shrubbery.

10.63 Individuals using vehicles foroutside operations should remain in thevehicle, leaving it only when necessary. Toprevent contamination of the interior ofthe vehicle, all windows and outside ventsshould be closed when dusty conditionsprevail. Vehicles provide only slight pro-tection from gamma radiation but they doprovide excellent protection from beta andprevent contamination of the occupants.

FOOD AND WATER

10.64 To the extent practicable, pre-vent fallout from becoming mixed intofood and water. Food and water which isexposed to radiation, but not contami-nated, is not harmed and is fit for humanconsumption. If it is suspected that foodcontainers are contaminated, they shouldbe washed or wiped prior to removal of thecontents. Food properly removed fromsuch containers will be safe for consump-tion.

10.65 Water in covered containers andunderground sources will be safe. Beforethe arrival of fallout, open supplies ofwater such as cisterns, open wells, orother containers should be covered. Shutoff source of supply of potentially contami-nated water.

REFERENCES

The Effects of Nuclear Weapons.Glas-stone, Samuel, 1964.

Handbook for Radiological Monitors.DOD/OCD, FGE-5.9, April 1963.

In Time of Emergency, OCD H-14,March 1968.

RADIOLOGICAL DECONTAMINATION

Although there are many forms of pro-tection against nuclear radiation, as welearned in the preceding chapter, they areobviously not foolproof. Even if they were100% effective, there is still the case ofunavoidable contamination, contaminationwhich could occur during the performanceof a critically important mission, contami-nation which could be deliberately andknowingly accepted. Obviously, then, we.need another RADEF tool to take care ofcontamination. That tool is DECONTAMI-NATION and this chapter will explain:

HOW to.tell if decontamination isnecessary

WHAT are the steps in decontamina-tion

HOW does a decon worker protecthimself from contamination

WHAT should be done to decontami-nate an area, a structure, anorange, somebody namedHenry, a cat, the power com-pany, a red sportshirt or afarm tractor

INTRODUCTION

11.1 Closely allied with the problem ofmonitoring, discussed in Chapter 9, is theproblem of decontamination. The two are,in fact, closely linked and cooperation andcoordination between monitors and decon-tamination personnel is a basic require-ment if wasted effort or unnecessary haz-ard are to be avoided.

WHAT IS CONTAMINATION?

11.2 As we saw in Chapter 6, the radio-active fallout from a nuclear explosionconsists of radioisotopes that have at-tached themselves to dust particles or

CHAPTER 11

water droplets. This material behavesphysically like any other dirt or moisture.In fact, the phenomena of, radioactive con-tamination is exactly the same as getting"dirty" EXCEPT that very small amountsof "dirt" are required to produce a hazardand that the "dirt" is radioactive.

WHAT IS DECONTAMINATION?

11.3 The objective of radiological de-contamination is to reduce the contamina-tion to an acceptable level with the leastpossible expenditure of labor and mate-ri,als, and with radiation exposure to de-contamination personnel held to a mini-mum commensurate with the urgency ofthe task. Radioactivity cannot be de,stroyed or neutralized, but in the event ofnuclear attack, the fallout radiation haz-ard could be reduced by removing radioac-tive particles from a contaminated surfaceand safely disposing of them, by coveringthe contaminated surface with shieldingmaterial, such as earth, or by isolating acontaminated object and waiting for theradiation from it to decrease through theprocess of natural radioactive decay.

11.4 This chapter is directed to thosepersons who are responsible for planningand establishing radiological decontami-nation operations in States and localities.It contains guidance on the various typesof decontamination procedures and therelative effectiveness of each.

DECONTAMINATION OF PERSONNELAND CLOTHING

11.5 State and local public welfare de-partments and agencies, as the welfarearms of their respective governments,have primary responsibility for planningand preparing the facilities and develop-

1 53

15 6

ing capabilities essential to provide emer-gency welfare at the local level. Voluntarysocial welfare agencies will assist.

11.6 Decontamination of personnel andclothing of personnel engaged in recoveryoperations would be the responsibility ofthe various operational services, such asfire departments, police departments, anddecontamination teams. Many personswould be responsible for decontaminationof themselves and their families in accord-ance with instructions of the local govern-ment.

PERSONNEL

11.7 It is important that all people, andparticularly those directing emergency op-erations, understand that the total radia-tion injury from fallout is a composite dueto several causes, including contaminationof the surrounding areas, contaminationof skin areas, and ingestion and inhalationof fallout materials. To keep the total ra-diation injury low, the effect of each po-tential source of radiation on the totalradiation exposure must be kept in mind,and eac. contributing element should bekept as low as operationally feasible. Nor-mally, ordinary personal cleanlineSs proce-dures will suffice for personnel decontami-nation in the postattack period.

11.8 All persons seeking shelter afterfallout starts should brush nr shake theirouter clothing before entering the shelterarea. Ordinary brushing will remove mostof the contaminated material from theshoes and clothing, and often may reducethe contamination to, or below a permissi-ble level. It is important to brush or shakefrom the upwind side. Under rainy condi-tions, the outer clothing should be re-moved before entering the shelter area.

Upon entering the shelter area and assoon as practicable, wash, brush, or wipethoroughly the exposed portions of thebody, such as the skin and hair. If suffi-cient quantities of water are available,persons should bathe, giving particular at-tention to skin areas that had not beencovered by clothing.

154

THE INJURED

11.9 It is desirable that contaminationof medical facilities and personnel be keptat a minimum. Medical personnel, whoseskills would be needed for the saving oflives, should be protected from radiationto the extent feasible. Persons entering amedical treatment station or hospitalshould be monitored, decontaminated ifnecessary, and tagged to show that he isnot contaminated. To do this, a check pointcould be established at a shielded locationat each medical treatment station andhospital. Although decontamination proce-dures for the injured are the same asthose previously described for personneldecontamination (i.e., the removal of outerclothing, and other clothing if necessary,and finally the washing of contaminatedbody areas, if required) special factors alsomust be considered. In the face of urgencyfor decontamination, there will be manycasualties who are unable to decontami-nate themselves and whose condition willnot permit movement. For some cases amedical examination will determine thatfirst aid must take priority over decontam-ination. Also, it may not be possible todecontaminate some casualties without se-riously aggravating their injuries. Thesewill have to be segregated in a controlledarea of the treatment facility.

CLOTHING

11.10 Thorough decontamination ofclothing can be deferred until after theemergency shelter period when supplies ofwater and equipment are available. Equip-ment for decontamination of clothing in-cludes whisk brooms, or similar types ofbrushes, vacuum cleaners (if available)and laundry equipment. For more effec-tive decontamination of clothing, washerand dryer equipment should be available.Since there is normally little accumulationof "dirt" in a washing machine, virtuallyall of the decontaminant would be flusheddown the drain. The chance of significantresidual contamination of the washing ma-chine appears to be quite small. Althoughthere is little serious danger involved in

washing, direct contact with the contami-nation should be kept to a miniumum.

11.11 The procedures for decontamina-tion of clothing should be as follows: First,brush or shake the clothing outdoors; sec-ond, vacuum clean; third, wash; andfourth, if the previous procedures.* are noteffective, allow natural radioactive decay.Monitoring of the clothing upon comple-tion of each step will indicate the effective-ness of the decontamination procedureand indicate any need for further decon-tamination. In many cases, dependingupon the amount and kind of radioactivecontaminant, brushing or simply shakingthe clothing to remove the dust particlesmay reduce the contamination to a negli-gible amount. If two thorough brushingsdo not reduce the contamination to anacceptable level, vacuum cleaning shouldbe attempted. Care should be taken indisposing of the contaminated materialfrom the dust bag of the vacuum cleaner.If the clothing is still contaminated afterdry methods of decontamination are com-pleted, it should be laundered. Clothingusually can be decontaminated satisfac-torily by washing with soap or detergent.

11.12 Any clothing that still remainshighly contaminated should then be storedto allow the radioactivity to decay. Stor-age should be in an isolated location sothat the contaminated clothing will notendanger personnel.

DECONTAMINATION OF FOOD,AGRICULTURAL LAND AND WATER

11.13 State and local public agencies,assisted by radiological defense personnel,will be responsible for the decontamina-tion of food and water. Stored foods inwarehouses, markets, etc., will be the re-sponsibility of the agency controlling thedistribution of the food items. Water sup-ply personnel of the local government orprivate organizations will be responsiblefor monitoring, and if required, decontami-nation of the water supplies they operate.Each person or family not expecting to beprotected in a community shelter, is re-sponsible for providing, before attack, suf-ficient food and \ water to supply its needs

for at least 2 weeks, since outside assist-ance may not be available during thisperiod.

FOOD

11.14 The following guidance is pro-vided for individuals and groups who needto use food which may have been contami-nated with fallout. Before opening a foodpackage, the package should be wiped orwashed if contamination is suspected.Caution should be taken when wiping orwashing outer containers to avoid contam-inating the food itself. When possible, thepackage surface should be monitored witha radiation detection instrument beforeremoving the food as a check on the effec-tiveness of the decontamination proce-dure.

11.15 Meats and dairy products thatare wrapped or are kept within closedshowcases or refrigerators should be freefrom contamination. Fallout on unpack-aged meat and other food items could pres-ent a difficult salvage problem. Freshmeat could be decontaminated by trim-ming the outer layers with a sharp knife.The knife should be wiped or washed fre-quently to prevent contaminating the in-cised surfaces.

11.16 Fruits and vegetables harvestedfrom fallout zones in the first month pos-tattack may require decontamination be-fore they can be used for food. Decontami-nate fruits and vegetables by washing theexposed parts thoroughly to remove fal-lout particles, and if necessary, peeling,paring or removing the outer layer in sucha way as to avoid contamination of theinner parts. It should be possible to decon-taminate adequately fruits, such as ap-ples, peaches, pears, and vegetables, suchas carrots, squash, and potatoes, by wash-ing and/or paring. This type of decontami-nation can be applied to many food itemsin the home.

11.17 Animals should be put undercover before fallout arrives, and shouldnot be fed contaminated food and water, ifuncontaminated food and water are avail-able. If the animals are suspected of beingexternally contaminated, they should be

lets155

washed thoroughly before being processedinto food.

11.18 Even when animals have re-ceived sufficient radiation to cause latersickness or death, there will be a shortperiod (1 to 10 days following exposure,depending on the amount) when the ani-mals may not show any symptoms of in-jury or other effects of the radiation. Ifthe animals are needed for food, if theycan be slaughtered during this time with-out undue radiation expo-sure to theworker, and if no other disease or abnor-mality would cause unwhOlesomeness, themeat would be safe for hse as food. In thebutchering process, care should be takento 'avoid contamination of the meat, and toprotect personnel. The contaminated partsshould be disposed of in a posted locationand in such a manner as to present anegligible radiological or sanitation haz-ard. If any animal shows signs of radiationsickness, it should not be slaughtered forfood purposes until it is fully recovered.This may take several weeks or months.Animals, showing signs of radiation sick-ness (loss of appetite, lack of vitality, wa-tery eyes, staggering or poor balance)should be separated from the herd becausethey are subject to bacterial infection andmay not have the recuperative powersnecessary to repel diseases. They couldinfect other animals of the herd.

AGRICULTURAL LAND

11.19 The uptake of radioactive falloutmaterial would be a relatively long termprocess, and the migration of fission prod-ucts through the soil would be relativelyslow. Therefore, crops about to be har-vested at the time fallout occurs would nothave absorbed great amounts of radioac-tive material from the soil. However, ifcrops are in the early stages of growth inan intense fallout area, they will absorbradioactive materials through their leavesor roots and become contaminated. Thus,if eaten by livestock or man, it may causesome internal hazard. Before use, the de-gree of contamination should be evaluatedby a qualified person. Foods so contami-nated could not be decontaminated easily

1 56

1 5;1

because the contaminants would be incor-porated into their cellular structure. Donot destroy these contaminated foods.

11.20 Liming of acid soil will reduce theuptake of strontium since the plant sys-tem has a preference for calcium overstrontium and has some ability to discrim-inate: The plant's need for calcium leads tothe absorption of the similar elementstrontium. In soils low in exchangeablecalcium, more strontium will be taken upby the plant. By liming acid soils, morecalcium is made available to the plant andless strontium will be absorbed.

11.21 Another method to limit the up-take of strontium is to grow crops with lowcalcium content such as potatoes, cereal,apples, tomatoes, peppers, sweet corn,squash, cucumbers, etc., on areas of heavyfallout. Other foods with high calcium con-tent such as lettuce, cabbage, kale, broc-coli, spinach, celery, collards, etc., could begrown in areas of relatively light fallout.

WATER

11.22 Following a nuclear attack, waterin streams, lakes and uncovered storagereservoirs might be contaminated by ra-dioactive fallout. The control of internalradiation hazards to personnel will be de-w en t, in large part, upon proper selec-th,,, and treatment of drinking water.

11.23 If power is not available forpumping, or if fallout activity is too heavyto permit operation of water treatmentplants, the water stored in the home maybe the only source of supply for severalweeks. Emergency sources of potablewater can be obtained from hot watertanks, flush tanks, ice cube trays etc. It isadvisable to have a 2-weeks emergencywater ration (at least 7 gallons per person)in or near shelter areas.

11.24 Emergency water supplies maybe available from local industries, particu-larly beverage and milk bottling plants, orfrom private supplies, country clubs, andlarge hotels or motels.

11.25 If contaminated surface watersupplies must be used, both conventionaland specialized treatment processes maybe employed to decontaminate water. The

degree of removal will depend upon thenature of the contaminant (suspended ordissolved) and upon the specific radionu-clide content of the fallout.

11.26 Radioactive materials absorbedin precipitates or sludges from watertreatment plants must be disposed of in asafe manner. Storage in low areas or pits,or burial in areas where there is littlelikelihood of contaminating undergroundsupplies; is recommended.

11.27 Several devices for treating rela-tively small quantities of water underemergency conditions have been tested.Most of them use ion exchange or absorp-tion for removal of radioactive contami-nants.

a. Small commercial ion exchange unitscontaining either single or mixed-bed res-ins, designed to produce softened or demi-neralized water from tap water, could beused to remove radioactive particles fromwater. Many of them have an indicatorwhich changes the color of the resins toindicate the depletion of the resins' capac-ity. 'rests of these units have indicatedremovals of over 97 percent of all radioac-tive materials.

b. Emergency water treatment unitsconsisting of a column containing several2-inch layers of sand, gravel, humus,coarse vegetation, and clay have beentested for removal of radioactive materialsfrom water. This type of emergency watertreatment unit removed over 90 percent ofall dissolved radioactive materials.

c. Tank-tyre home water softeners arecapable of removing up to 99 percent of allradioactive materials, and are especiallyeffective in the removal of the hazardousstrontium 90 and cesium 137 contami-nants.

DECONTAMINATION OF VEHICLES AND .

EQUIPMENT

11.28 Decontamination of vehicles andequipment of the various operational serv-ices, such as fire departments, police de-partments, and decontamination teams,will be the responsibility of the variousservices, aided by radiological defenseservices. Individuals will be responsible

for decontamination of their own vehiclesand equipment in accordance With instruc-tions of local government.

EXTERIOR OF VEHICLES AND EQUIPMENTAND VEHICLE INTERIORS

11.29 The simplest and most obviousmethod for partial decontamination of ve-hicles and equipment is by water hosing.Quick car-washing facilities are excellentfor more thorough decontamination.

11.30 Special precautions should beused when vehicles and equipment arebrought in for maintenance. The malfunc-tioning part of the vehicle or equipmentshould be checked for excessive contami-nation.

11111r=

t

FIGURE 11.31.7EquipMent decontamination.

11.31 Hosing should not be used on up-holstery or other porous surfaces on theinterior of vehicles, as the water wouldpenetrate and carry the contaminationdeeper into the material.

11.32 The interior of vehicles can bedecontaminated by brushing or vacuumcleaning. Procedures for decontaminatinginteriors of vehicles by vacuum cleaningare similar to those used on the interior ofstructures.

VEHICLES AND EQUIPMENT USED BYDECONTAMINATION PERSONNEL

11.33 Upon completion of missions in acontaminated area, vehicles and equip-ment used by decontamination personnelshould be monitored, and decontaminated

160157

if necessary. Complete decontaminationmay not be necessary, but attempts shouldbe made to reduce the hazard to tolerablelevels.

11.34 A decontamination station set upat a control point adjacent to the stagingarea would be the best place for decontam-inating vehicles and equipment. A pavedarea would be desirable so that it could behosed off after the equipment is decontam-inated. Monitoring should follow the appli-cation of each decontamination method.

DECONTAMINATION OF VITAL AREASAND STRUCTURES

11.35 The operational planning aspectsof decontamination of vital areas andstructures are very complex and requiretrained decontamination teams from gov-ernment services, industry, and privateand public utilities under the direction of adecontamination specialist. All methodsdescribed in this chapter are commontechniques with which personnel of theemergency services are generally familiar.Operational details associated with use ofthe equipment are not discussed. How-ever, operational aspects peculiar to ra-diological recovery are emphasized. Themethod of decontamination selected willdepend upon the type and extent of con-tamination, type of surface contaminated,the weather and the availability of person-nel, material, and equipment. Each type ofsurface presents an individual problemand may require a different method ofdecontamination. The type of equipmentand skills required for radiological decon-tamination are not new. Ordinary equip-ment now available, such as water hoses,street sweepers, and bulldozers, and theskills normally used in operating theequipment are the basic requirements forradiological decontamination.

PAVED AREAS AND EXTERIOR OFSTRUCTURES

11.36 Decontamination of paved areasand the exterior surface of structures re-quires two principal actions; loosening thefallout material from the surface and re-

158

161

moving the material from the surface to aplace of disposal. Some decontaminationmethods for paved areas are street sweep-ing and motorized flushing. Firehosingmay be used for both paved areas and theexterior of structures.

11.37 Street sweeping is termed a drydecontamination method because water isnot used. There are many advantages ofthis method over wet methods. In the ab-sence of adequate water supplies for largescale decontamination procedures, drystreet sweeping would be the -preferredprocedure. Also, during cold weather, wetdecontamination procedures may not bepractical.

11.38 Most commercial street sweepershave similar operating characteristics. Apowered rotary broom is used to dislodgethe debris from streets into a conveyorsystem which transports it to a hopper.Thus, a removal and bulk transport sys-tem is inherent in the design. Some swee-pers utilize a fine water spray to dampenthe surface ahead of the pickup broom tolimit dust generation. This use of a sprayprevious to brushing would reduce the ef-fectiveness of the procedure for decontam-ination because the combination wouldtend to produce a slurry which wouldmake complete removal of surface contam-ination more difficult.

11.39 A variation in equipment of thistype is the sweeper in which the broomsystem is enclosed in a vacuum equipped

rntetttit,t-t,

FIGURE 11.38.Commercial street sweeper.

housing. The material picked up by thebroom and the dust trapped by the filtersare collected in a hopper.

11.40 Normally a single operator is re-quired per street sweeper. However, be-cause fallout material would be concen-trated in the hopper, the operator may besubjected to a high radiation exposure.This may make it necessary to rotate per-sonnel for street sweeping operations. Theoperator should be instructed to keep aclose check on his dosimeter, and dumpthe hopper often at the predesignated dis-posal area, as precautions to keep his ac-cumulated radiation exposure low.

11.41 In decontaminating paved areasby street sweeping, decontamination fac-tors' better than 0.1 can be realized, de-pending upon the rate of operation andthe amount of fallout material.

11.42 The flushing or sweeping actionof water is employed in decontaminatingpaved areas by motorized flushing. Con-ventional street flushers using two for-ward nozzles and one side nozzle under apressure of 55 pounds per square inch (psi)are satisfactory for this purpose. In flush-ing paved areas, it is important that fal-lout material be moved towards drainagefacilities.

11.43 Decontamination factors of 0.06to 0.01 can be realized by motorized flush-ing, depending upon the rate of operationand the type and roughness of the surface.

11.44 The flushing or sweeping actionof water also is used in decontaminatingpaved areas and the exterior of structuresby firehosing. Equipment and personnelare commonly available for this method.Employment of the method is dependentupon an adequate postattack water sup-ply. When decontaminating paved areasand structures, it is important that falloutmaterial be swept toward predesignateddrainage facilities, and, where possible,downwind from operational personnel.

11.45 Standard fire fighting equipmentand trucks equipped with pumping appa-ratus may be used in this decontamination

' For decontamination of vital areas and structures, the term decon-tamination factor (OF) is used. This represents the decimal fractionremaining after decontamination is accomplished.

method. The most satisfactory operatingdistance from nozzle to the point of impactof the water stream with open pavementsis 15 to 20 feet. On vertical surfaces, thewater should be directed to strike the sur-face at an angle of 30° to 45°. As many asthree men per nozzle may be required forfirehosing.

11.46 When decontaminating roughand porous surfaces or when fallout mate-rial is wet, the use of both firehosing andscrubbing are recommended for effectivereduction of the radiation hazard. Initialfirehosing should be done rapidly to re-move the bulk of fallout material. Hosingfollowed by scrubbing would remove mostof the remaining contamination. Two addi-tional men per hose may be required forthe scrubbing operation.

11.47 Decontamination factors between0.6 and 0.01 can be realized by firehosingtar -and gravel roofs with very little slope,and 0.09 to 0.04 in decontaminating compo-sition shingle roofs that slope 1 foot inevery 21/2 feet. Decontamination factors of0.06 can be realized in firehosing of pave-ments.

UNPAVED LAND AREAS

11.48 Decontamination of unpaved landareas can be accomplished by removingthe top layer of soil, covering the areawith uncontaminated soil, or by turningthe contaminated surface into the soil byplowing. The two latter methods employsoil as a shielding material.

11.49 The effectiveness of any of themethods is dependent on the thoroughnesswith which they are carried out. Spills ormisses and failure to overlap adjoiningpasses should be avoided. Reliance shouldbe placed on radiation detection instru-ments to find such areas, although inheavily contaminated areas the falloutmaterial may be visible. Large spills ormisses should be removed by a second passof the equipment. Small areas can be de-contaminated with the use of shovels,front end loaders, and dump trucks.

11.50 Large scale scraping operationsrequire heavy motorized equipment toscrape off the top layer (several inches) of

16159

te; 't*411$10 14.

m

FIGURE 11.48.Turning contaminated soil.

contaminated soil, and carry the soil tosuitable predesignated dumping grounds.The contaminated soil should be deposited100 or more feet beyond the scraped areaif possible; if not, at least to the outer edgeof the scraped area. Scraping can be donewith a motorized scraper, motor grader, orbulldozer. Effectiveness of the proceduredepends upon the surface conditions. Indecontaminating unpaved areas by scrap-ing, decontamination factors over 0.04 canbe realized if all spills and misses arecleaned up.

11.51 The motor grader is designed forgrading operations, such as for spreadingsoil or for light stripping. This grader canbe used effectively on any long narrowarea where contaminated -soil can bedumped along the edge of the cleared area.The blade should be set at an angle suffi-cient for removing several inches of thecontaminated soil. The scraped up earthshould be piled along the ground in awindrow parallel to the line of motion. Thewindrow can be either pushed to the sideof the contaminated field and buried bythe grader or removed by other pieces ofearthmoving equipment.

11.52 The bulldozer can he useful inscraping small contaminated areas, bury-ing material, digging sumps for contami-nated drainage, and in back-filling sumps.It would be particularly suitable in roughterrain where it could be used to clearobstructions and as a prime mover to as-sist in motorized scraping. The contami-160

nated soil stripped off by a bulldozershould be deposited at the outer edge ofthe scraped area, or beyond, if practicable.

11.53 Filling may offer no advantageover scraping, either in effectiveness orspeed. Its principal use would be wherescraping procedures could not be used,either because of rocky ground or becauseof permanent obstructions. Filling can beused in combination with other methods toachieve a low decontamination factor. Theobject of filling is to cover the contami-nated area with uncontaminated soil or fillmaterial to provide shielding. For theseoperations a motorized scraper, bulldozer,mechanical shovel, or dump truck andgrader may be used.

11.54 The effectiveness of filling rela-tively flat surfaces will vary with thedepth of fill. A 6-inch fill of earth canreduce the radiological hazard directlyabove to a decontamination factor of 0.15,and a 12-inch fill can reduce the hazard toa decontamination factor of 0.02.

11.55 Plowing provides earth shieldingfrom radiation by turning the contami-nated soil under. It is a rapid means ofdecontamination, but may not be suitablein areas in which personnel must operateor travel over the plowed surface. Thedepth of plowing should be from 8 to 10inches. In decontaminating unpaved landareas by plowing, decontamination factorsof 0.2 can be realized if the depth of plow-ing is from 8 to 10 inches.

11.56 Two or more methods can be ap-plied in succession, achieving a reductionin the radiation field not possible, practi-cal, or economical with one method alone.Any of three combinations of methodsscraping and filling, scraping and plowing,or plowing, leveling and fillingcould beeffective in unpaved areas. In some cases,any of the three might be more rapid thanindividual removal of spillage. The equip-ment used would be the same as in compo-nent methods previously discussed.

11.57 Because large earthmovingequipment could not be used in smallareas, such as those around a building,other methods of decontamination must beused. If the area is large enough for a

G 3

small garden type tractor, or frontendloaders, these can be used for plowing andscraping the soil. Improvised methods ofscraping small areas, such as using a jeepto tow a manually operated bucket scoop,could be used. There would remain someareas requiring hand labor with shovels,to dig up or remove the top layer of soil, orsod. Equipment and manpower require-ments for loading and hauling the soil to adisposal area should be included in esti-mate of decontamination "costs". Therates of operation of these methods wouldvary with the type of terrain and its vege-tative cover. The various procedures canresult in decontamination factors of 0.15 to0.1.

INTERIOR OF STRUCTURES

11.58 The two principal methods for de-contaminating interiors of structures arevacuum cleaning and scrubbing with soapand water. Vacuum cleaning is useful forthe decontamination of furniture, rugs,and floors. Floors, tables, walls, and othersurfaces can be decontaminated by scrub-bing them with soap and water. Mild de-tergents can be substituted for soap. Rags,hand brushes (or power-driven rotarybrushes, if available), mops, and broomsare suitable for scrubbing.

COLD WEATHER DECONTAMINATIONPROCEDURES

11.59 Cold weather decontaminationmethods will depend upon the weatherconditions prior to and after the arrival offallout. Various problems such as fallouton various depths of snow, on frozenground or pavement, mixed with snow orfreezing rain, and under various depths ofsnow could occur after a contaminatingattack. The presence of snow or ice wouldcomplicate the situation since large quan-tities of these materials would have to bemoved along with the fallout material. Inaddition, snow and ice could cause loss ofmobility to men and to equipment. Falloutmay be clearly visible as a dark film orlayer of soil or powder on or within snowunless it precipitates with the snow.

11.60 The principal cold weather decon-tamination methods for paved areas, andstructures are: (1) Snow loading, (2) sweep-ing, (3) snow plowing, and (4) firehosing.

11.61 Snow loading is accomplishedwith a front-end loader and is applicablefor snow covers. When fallout is on snow,the front-end loader bucket is used toscoop up the contaminant and top layer ofsnow, which are forced into the bucket bythe forward motion of the vehicle. Thesnow cover should be observed closely forpieces of contaminated debris which mayhave penetrated to some depth. The loadercarries the contaminated material to adump truck which removes it to a dumpingarea. The remaining clean snow is re-moved by normal snow-removal proce-dures. Decontamination factors of approxi-mately 0.10 can be realized by this process,depending mainly on the amount of spil-lage.

t1.1.1.81., LMerrun.

FIGURE 11,61.Front-end loader.

11.62 Pavement sweepers can be usedfor fallout on dry pavement, traffic-packedsnow, or reasonably level frozen soil or ice.Pavement sweepers are more effectivethan firehosing where there is a drainageproblem, or when temperatures are low,Sweepers will not effectively pick up con-taminant on wet pavement above thefreezing or slush point on ice or packedsnow. Decontamination factors are ap-proximately 0.10.

11.63 Snow plowing is applicable for alldepths of contaminated snow. When fal-

161

164

lout is precipitated with snow, all of thesnow must be removed to the dumpingarea. Blade snowplows, road graders, orbulldozers in echelon, windrow the con-taminated snow to one side until the bladesare stalled by the snow mass. A snowloader can be used to put the contami-nated snow in dump trucks, which move itto the dumping area. Decontaminationfactors of 0.15 can be realized by thismethod.

11.64 Firehosing is possible and can beused on paved areas and exteriors ofstructures slightly below freezing temper-atures.. Firehosing is not recommendedwhere slush from snow will clog drains.Problems associated with firehosing below32° F are freezing of the water, therebysealing the contaminant in ice and causingslippery conditions for the operating per-sonnel. The principle of operation, and-equipment used in temperate weather,will be the same under cold weather condi-tions. The effectiveness of firehosing willdepend on surface and standard exposure

rates, and the decontamination factorswill vary from 0.5 to 0.1.

11.65 In small areas, such as roofs ofbuildings, and around buildings, wherelarge snow removal equipment could notbe used, other methods of decontamina-tion must be used. With small amounts ofdry snow on roofs or paved areas, sweep-ing the area with brooms is satisfactory.With larger amounts of snow, with thefallout material on top of the snow, ormixed with the snow, shoveling the snowand removing it to an area where largesnow removal equipment can be used ispracticable. The rates of operation of thesemethods would vary with the amount ofsnow to be removed and the type of sur-face to be decontaminated. The variousprocedures can result in decontaminationfactors of 0.15 to 0.1.

11.66 In order to locate needed servicesand to guide the movement of decontami-nation equipment through heavy snowcovers, colored poles should mark streetcorners, drains, hydrants and hidden ob-

AGENT TYPE OF SURFACE. SITUATIONS

STEAM PAINTED OR OILED, NONPOROUS ROOMS WHERE CONTAMINATED SPRAY CANBE CONTROLLED. BUILD:14GS.

DETERGENTS NON-POROUS (METAL, PAINT, PLASTICS,ETC.). INDUSTRIAL FILMS,OLS, 8 GREASES.

SURFACE COVERED WITH ATMOSPHERICDUST AND GREASE. FIXED OR MOVABLEITEMS.

COMPLEXINGAGENTS

-METAL OR PAINTED.

LARGE, UNWEATHERED SURFACE. SURFACESWHERE CORROSION IS NOT TOLERABLE.

45 AN ADJUNCT TO WATER OR STEAMTREATMENT.

* ORGANICSOLVENTS

PAINTED OR GREASED.FINAL CLEANING. WHERE COMPLETE IM-MERSION DIPPING OPERATIONS AREPOSSIBLE. MOVABLE ITEMS.

* INORGANICACID

METAL OR PAINTED,ESPECIALLY THOSEEXHIBITING POROUS DEPOSITS, SUCH ASRUST, MARINE GROWTH.

DIPPING OF MOVABLE ITEMS.

* CAUSTICS PAINTED. LARGE, SURFACES. DIPPING OF PAINTEDOBJECTS.

ABRASIONS METAL AND PAINTED LARGE, WEATHERED SURFACES. FIXED ORMOVABLE ITEMS.

* UNUSUAL HAZARDS ARE ASSOCIATED WITH THESE METHODS, AND SPECIAL PRECAUTIONS ORPROTEC7IVE EQUIPMENT AND REQUIRED.

162

FIGURE 11.67.Small scale decontamination methods.

166

stacles. Open ground areas planned forpostattack use should be cleared of rocks,stumps, etc., prior to the arrival of snow.

11.67 Figure 11.67 lists other decon-tamination methods that may be used on asmall scale, for specific areas of high con-tamination.

16

REFERENCE

Radiological Defense Planning and Op-erations Guide.SM-11.23.2, Revised No-vember 1968.

163

CHAPTER 12

RADEF OPERATIONS

The man-in-the-street often thinks ofmodern war as "push button war" withvisions of all our forces moving automati-cally at the pressing of a button on thePresident's desk. This just isn't so, ofcourse. If there is no such thing as "pushbutton war", how much more so is thereno such thing as "push button radiologicaldefense." We may have sensitive machinesand instruments to measure nuclear ra-diation, but these devices must be oper-ated, interpreted and the informationacted upon. It is the prime objective of thischapter to explain how and by whomRADEF operations are carried out, andhow the responsibilities for such opera-tions vary among different types ofRADEF personnel and within the variouslevels of government.

INTRODUCTION

12,1 To be effective, radiological de-fense countermeasures require rapid de-tection, measurement, reporting, plotting,analysis, and evaluation of fallout contam-ination for use during the early periodafter attack and trained radiological per-sonnel are needed at all levels of the gov-ernmentFederal, State, and local, to pro-vide such information and skills.

12.2 The RADEF Officer and otherRADEF personnel, in carrying out theirresponsibilities, act in a "staff" ratherthan in a ",command" capa-ity. They pro-vide an important part of the technicalinformation upon which Civil Prepared-ness command decisions will be based.

12,3 It must be stressed that thoughRADEF personnel serve in a staff capac-ity at the various Jevels of government,fallout radiation is a physical not a politi-cal phenomenon. In short, fallout does notrecognize city, state, or county bounda-1 64

ries. As a consequence, effective RADEFcountermeasures demand cooperationamong` tine various RADEF organizations.This cooperation must be both horizontaland vertical: horizontal among organiza-tions on the same level of government(e.g., different counties or States); verticalamong levels (e.g., city and State). Also,cooperation must not wait until an at-tackit must be planned for and workedat now.

WHO WILL CARRY OUT RADEFOPERATIONS?

12.4 To carry out the various functionsof radiological defense, there is need forRadiological Defense Officers, AssistantRadiological Defense Officers, Monitors,Analysts, and Plotters. The following par-agraphs define each of these positions andsummarize duties and responsibilities.These definitions are necessary at thispoint to avoid repetition in the later level-by-level description of the operationalprocess.

DEFINITIONS

12.5 Radiological Defense Officer.Aperson who has been trained to assumethe responsibility for policy recommenda-tions for the radiological defense of aState, county, locality, facility, or a rela-tively large group of organized personnel.

This officer must be conversant withmeasurement and reporting procedures,capable of evaluating the probable effectsof reported radiation on the people andtheir environment, and capable of recom-mending appropriate protective measures(such as remedial movement, shelter, anddecontamination) to be taken as a result ofthe evaluation.

16?

12.6 Assistant Radiological Defense Of-ficer.Definition similar to that of theRadiological Defense Officer. Less admin-istrative capability is required, but thecapabilities listed above are required. Itshould be borne in mind that the term"assistant" is an organizational distinc-tion rather than indicative of anythingless than 100% possession of all necessaryRADEF Officer qualifications.

12.7 Monitor.A person who has beentrained to detect, record, and report radia-tion exposures and exposure rates. He willprovide limited field guidance on radiationhazards associated with operations towhich he is assigned.

12.8 Analyst.A person who has beentrained to prepare monitored radiologicaldata in analyzed form for use in the areaserved as well as by other levels of govern-ment to which reports of such data aresent. He will also evaluate the radiationdecay patterns as a basis for estimates offuThre exposure rates and radiation expo-sures associated with emergency opera-tions.

12.9 Plotter.A person trained to re-cord incoming data in appropriate tabularform and to plot such data on maps. Hewill also perform routine computations un-der direction.

LEVEL-BY-LEVEL RADEF OPERATIONS

12.10 Fallout monitoring station activi-ties.Upon receipt of warning of likelyattack, monitors ;at least four should beassigned to each station to provide 24-hourcontinuous monitoring), will be advised ofthe likelihood of attack. They will thenbegin to carry out the emergency plan.Upon arrival at the monitoring station, allequipment and procedures should bechecked and an operational readiness re-port made to the emergency operatingcenter (EOC) RADEF Officer, thus verify-ing that the station is ready to operate.The monitoring station will send the EOCa FLASH REPORT the first time the un-sheltered exposure rate equals or exceeds0.5 R/hr. The station also sends scheduledEXPOSURE RATE REPORTS and EXPO-SURE REPORTS, plus SPECIAL RE-

16

PORTS whenever a declining rate trend isreversed and there is a rapid increase.

NOTE

For the monitoring station, and for alllevels, the time before fallout arrives isa time of intense activity. Not a mo-ment should be lost by.RADEF person-nel between arrival at assigned loca-tions and performance of all prescribedreadiness actions.

12.11 Shelter monitoring activities.After checking his equipment, the sheltermonitor will make an operational readi-ness report to the shelter manager (who,in turn, will report that fact to the EOC).The shelter monitors will measure andreport to the shelter manager the dailycumulative exposure of shelter occupants.This in-shelter exposure will be reportedto the EOC if it exceeds 75 R. Should thisbe exceeded during the first two days inshelter, or should the exposure rate ex-ceed 10 R/hr, an EMERGENCY REPORTshould be sent to the EOC reques'ting ad-vice. The shelter monitor will also reportto the shelter manager as to the dailyexposure rate. Should any occupied area ofthe shelter be receiving a rate of 2 R/hr ormore, the monitor will report on the expo-sure rates within various areas of theshelter so that the manager may moveshelter occupants to safer positions in theshelter. The shelter may also be desig-nated as a station in the regular monitor-ing network, in which instance the opera-tions described in paragraph 12.10 willalso be performed.

12.12 The local emergency operatingcenter.Local emergency operating cen-ters first determine that monitoring sta-tions are in a state of operational readi-ness. Subsequently, the local EOC's willreceive reports from these monitoring sta-tions and shelters and will transmit sum-mary-type data to the State EOC. In addi-tion, and as previously agreed upon, thisdata can be made available to neighboringEOC's, The reports to the State EOC willinclude flash reports made upon their re-ceipt from any of the monitoring stationswithin the network of the local EOC. Expo-sure and exposure rate reports will also be

165

made in summary form to the State EOCas determined by the State Civil Prepared-ness Plan. The exposure rate report willinclude a typical exposure rate if the areawithin the jurisdiction of the local EOC issmall. The local EOC's will also report theaccumulated unsheltered exposure atleast once each day to the State EOC. Itshould be noted that the term "local EOC"is used here to designate the operatingechelon or echelons between the monitor-ing station and the State EOC. (A very_large city may have local area EOC's sand-wiched in between the stations-- and thelocal EOC's.) In addition, some States mayhave county EOC's between the local andState EOC's. These various. EOC's mayreport to a sub-State EOC depending onthe State's geography and population.

12.13 The State Emergency OperatingCenter.This -is the command level foreach State's Civil Preparedness organiza-tion. The State EOC receives reports fromlocal, local area, county and/or sub-StateEOC's within the State and will, in turn,send to the appropriate DCPA regionaloffice flash reports summarizing thespread of fallout across the State as wellas exposure rate analyses. The State EOCwill also send selected flash reports asappropriate to the local EOC to alert themof approaching fallout and exposure ratereports to advise local centers of exposurerates in neighboring communities. Neigh-boring States, in addition, and Canadianprovinces can also be sent flash reportsand exposure rate analyses by the StateEOC. State EOC's are tied into a national

166

RADEF system through the DCPA re-gions to which they report.

12.14 In addition to collecting and re-porting data, RADEF Officers at the State(sometimes sub-State) level have the re-sponsibility of providing the data for fal-lout warning and other fallotit advisoriesissued to the general populace by the Gov-ernor or other properly designated civilauthority. There are many possible typesof advisories which could be issued, (1,*,,44.pending upon local conditions.

EMERGENCY OPERATING CENTERPERSONNEL

12.15 Communities over 500 population,State and county governments, and cer-tain field installations of Federal agenciesrequire other radiological defense person-nel in addition to monitors. These are theRADEF Officers, Assistant RADEF Offi-cers, Plotters, and Analysts located atEOC's. Their functions were summarizedin paragraphs 12.5 to 12.9. As a rule, ruralareas will need only monitors. The numberof Assistant Radiological Defense Officerswill depend on community size. Large ci-ties will require several, while small com-munities may require none.

12.16 A suggested guide to the numberof Analysts and Plotters for communitiesof various sizes is shown in Figure 12.16. ARadiological Defense Officer can "doublein brass," filling in for a variety of RADEFpersonnel where no other individual isavailable to perform the particular func-tion.

POPULATION PLOTTERSNEEDED

ANALYSTSNEEDED

Under 2,500 1 1

2,500 to 25,000 1 1

25,000 to 250,000 4 2

Over 250,000 6 3

FIGURE 12.16.Requirements guide for plotters and analysts.

NOTE ,

This is a "one-way street," however,because an analyst, for example, CAN-NOT pe?form the functions of a Ra-diological Defense Officer unless he ISa Radiological Defense Officer.

A REPORTING NETWORK

12.17 The monitoring stations must be

170

linked into a well organized and extensivereporting system, running up through thesub-State and State organization all theway to the national center. It is vital thatthe data produced at each level shouldsupport the higher levels. Also, data mustbe consistent between and among report-ing levels. No correct conclusions can bedrawn from data that employ differentunits of measurement or time baseS.

167

CHAPTER 13

RADEF PLANNING

In a church in Caracas, Venezuela, apickpocket, hoping to stir up some excite-ment during which he could work moreeasily, shouted "Fire." There was no firebut the congregation stampeded anyway.When the screaming mob finally burst outof the church, many huddled forms wereleft behind, trampled and broken. Fifty-three.9f them, including 22 children, wouldnever discover that there was no fire.

After the Titanic smashed against aniceberg a Mrs. Dickinson Bishop left $11,-000 in jewelry behind in her stateroom,but asked her husband to dash back topick up a forgotten muff. Another passen-ger on the sinking vessel, Major ArthurPeuchen, grabbed three oranges and agood-luck pin, overlooking $300,000 in se-curities he had in his cabin. Still anotherpassenger carried into the lifeboat nothingbut a musical toy pig.

There are countless cases of personswho in their haste to escape hotel fires,jump from upper story windows locatedjust a few feet from a fire escape.

The cause of this strange and illogicalbehavior is panic and the cure is planning.

'The major objective of this chapter is todescribe the importance of planning toeffective Radiological Defense.

THE EXPERIMENTAL EVIDENCE

13.1 In a series of 42 varying experi-ments with from 15 to 21 subjects, thepsychologist Alexander Mintz dearlyshowed the wide difference betweenplanned 'and unplanned behavior in a pe-riod of stress. The experimental situationconsisted of a large glass bottle with anarrow mouth. Inserted in this bottle werea number of aluminum cones. These coneswere attached to strings each of which168

was held by one of the participants in theexperiment. The idea, of course, was topull the cones out of the bottle. Whenconditions such as we might have during asudden emergency arose and there was"every man for himself", traffic jams oc-curred. Sometimes but one or two coneswere jerked free before the rest werehopelessly snarled.

But, when the participants were giventime for prior consultation and planning,there were no traffic jams. In one instanceall the cones were removed in under 10seconds.'

13.2 But what happens when there areno plans? We saw the experimental evi-dence. Cones get jammed. Strings gettwisted. The evidence of real life is just assimply stated: people get killed and in-jured; property gets destroyed. It is saidthat casualty statistics are people with thetears wiped off. Let's look behind the sta-tistics and examine a few of the legion oftearful stories.

THEY HAD NO PLANS

13.3 A bustling city of 30,000 was lo-cated at the point where two swift streamsmet. The city was built along the low riverbanks, surrounded by steep hills. As aresult of this situation, the lower part ofthe city suffered from floods every spring.

13.4 Upstream was a huge dam, origi-nally built to store water for a canal butprogress made the canal uneconomical, soit was abandoned and maintenance haltedon the darn. Gradually the dam deterio-rated. Water seeped out in a hundred pla-ces and within a few years the water levelhad dropped to half. When a small break

Von - Adaptive Group Behavior, Alexander Mintz, Readings in Social'Psychology. p. 190-195.henry IIolt S Co. New York, 1952.

17l

occurred, the water level was low and onlypart of the city was flooded.

13.5 Subsequently, a hunting and fish-ing club leased the dam and the lake itimpounded. The club tried to repair thedam. Their work seemed sound. But intothe break had been dumped tree stumps,sand, leaves, straw and other debris. Lateron, heavy rains caused many leaks in thedam and floods in the city.

13.6 Finally, there was an even heavierrainfall. After six inches of rain, the waterlevel in the dam rose rapidly. Crews hiredby the hunting and fishing club worked torepair the leaks but the rising waters kepteating away at the rotten structure.

13.7 Finally, a civil engineer inspectedthe dam. He realized it would not hold andtried to get word to the city below. Therewere no telephones and the storms haddowned the telegraph wires. Word did notget through. Meanwhile, the workerswatched in horror as the waters began toroar over the top of the clam racing for thecity, 12 miles away and 400 feet lower inelevation.

13.8 A half million cubic feet of waterrushed through that breach picking up onthe way trees, houses, boulders. When itreached the city it was a wall 30 feet highmoving at 20 miles an hour. The result:annihilation! The city was destroyed, and2,000 people lost their lives in an instant ofterror.

13.9 But the disaster need never havehappened had the warnings of the damitself been heeded during the precedingquarter century. Even if no efforts hadbeen made to remove the causethe ob-viously unsound condition of the damitseems unbelievable that no one plannedfor a possible serious break, and no oneplanned a warning system.

AND STILL NO PLANS

13.10 But we need not go all the wayback to the Johnstown flood to see theeffect of lack of planning. The reatestmanmade disaster in recent ericanhistory is replete with examples of lack ofplanning, from its beginnings in the holdof a ship in Galveston Bay to its end a few

17

hours later in a devastated city, ravagedto the tune of 552 dead, 3,000 injured andmaimed and over $50,000,000 in propertydamage.

13.11 It all began with a few wisps ofsmoke from the cargo of fertilizer carriedon board the SS Grandcamp. A crewmaninvestigated, but even after shifting sev-eral bags of the fertilizer, he could findnothing. He tried throwing buckets ofwater in the direction of the smoke. Noeffect. Next he tried a fire extinguisher.Still no effect. So he called for a fire hose.But the foreman objected. Hosing downthe cargo would ruin it. The Captain or-dered the hatches battened down and theturning on of the steam jets,. Turning onsteam to fight fires is standard marinefirefighting practice, and has been foryears. But this fertilizer Was ammoniumnitrate, which, when heated to about 350degrees Fahrenheit, becomes a high explo-sive.

13.12 Someone should have known howto deal with this explosive fertilizer. Some-one should have made plans for putting outa possible fire in or near the nitrate. Butno one had. And so, at 12 minutes after 9on the morning. of April 16, 1947, the 10,-419 -ton Grandcamp and all those aboardwere blown to bits. The explosion, calcu-lated as equivalent to 250 five-ton block-busters (1.25 kilotons) going off at once,dropped 300-pound pieces of the Grand-camp 3 miles away. Two small planes,flying at about 1,000 feet above the harbordisintegrated from the tremendous con-cussion. The blast swept across the com-plex of oil refineries and chemical plants,smashing them flat and setting off otherexplosions and fires.

13.13 As a result of this explosion andthe later and even more violent blast fromanother ammonium nitrate laden ship, theSS High Flyer, chaos reigned in TexasCity. Though the citizens of the cityworked with courage and initiative to helpthe injured, for the first few hours theirwork was uncoordinated.

13.14 There was no disaster plan,13.15 The head of the Texas City disas-

ter organization is quoted as saying: "We

169

had an organization, but it was designedfor hurricane. We weren't prepared foranything like this. In a hurricane, youhave some warning and you can get yourorganization ready. But we had no warn-ing in this, aril our organization was scat-tered all over town. And do you Inow whathappened at our meeting to develop a dis-aster organization just 3 weeks before theexplosion? People pooh-poohed the idea!"2

MORE LACK OF PLANNING

13.16 On September 5, 1934, the SSMorro Castle steamed out of Havana har-bor. A seagoing hotel, the ship wascrammed with passengers heading back toNew York after a Caribbean vacation. Theship was equipped with all the latestequipment to detect, confine, and extin-guish fires.

13.17 Captain Wilmott was confident inthe fire safety of his ship. But 2 clays laterhe was dead of a heart attack and hissecond in command had scarcely gottenaccustomed to being Captain when a decknight watchman reported a fire.

13.18 After investigating, a belatedalarm was sounded and the crew tried toput out the fire. The ship was 'equippedwith fire doors which, if shut in time,might have kept the fire from spreadingpast the point of origin.

13.19 But no one had been assigned toclose the fire doors.

13.20 This, and other evidence of seri-ous planning deficiencies, caused the Act-ing Captain and Chief Engineer to be sent-enced to prison for incompetence and ne-glect of duty (they were later cleared by ahigher court) and the steamship line wasfined $15,000 for failure to er.r,)rce safetyregulations and for placing unqualifiedpersonnel in charge of the ship. The finalcost was 134 dead and $4,800,000 propertyloss.

ANOTHER CATASTROPHE

13.21 Or take the case of the formerFrench liner Nonnandie. The lack of plan-

'Quoted in THE FACE OF DISASTER, Donald Robinson. p. 130,Doubleday & Co., New York, 1959.

170

ning is summed up in a straight-from-the-shoulder report of the National Fire Pro-tection Association:

"The fire-spreading conditions aboardthis vessel had been allowed to becomeso bad during the execution of a $4,000,-000 conversion contract that a waywardspark from a cutting tool, inexcusablylanding in a kapok life preserver, wassufficient to culminate in the total de-struction of an uninsured $53,000,000ship. Because although the incipientoutbreak started in broad daylight un-der the eyes of 1,750 employees of thecontractorplus another 1,650 Navy,Coast Guard and subcontractor person-nelnot one of them had the rudimen-tary training required to stop thethingor even the wit to promptly callin somebody with the training. By thetime the fire department was sum-moned, the blaze had advanced so farthat a fifth alarm was required, putting

. to work more apparatus than is ownedby cities the size of St. Paul, Minn., orToledo, Ohio."

A FINAL TRAGEDY

13.22 Finally, there was the CoconutGrove fire.

13.23 The Coconut Grove was manythings. It was a fire trap infested withsafety violations (for which the owner waslater sentenced to prison for from 12 to 15years). It was the last hour for 450 per-sons. It was also an example of lack ofplanning, from the major exit door thatopened inward (where some 100 bodieswere found jammed), to the narrow stair-ways, to the inflammable decorations,even to the lack of planning in sending thevictims to hospitals.

13.24 Boston's City Hospital received129 'ire victims, thus greatly overloadingits facilities. Massachusetts General Hos-pital received only 39 and could have han-dled many more. Thirty other victims weredistributed among 10 other civilian hospi-tals. Seventy-eight percent were sent toCity Hospital simply because that is whereaccident victims usually were sent.

13.25 No one planned for the disaster

1 73

when masses of people would simultane-ously, become the victims of accident.

THEY HAD PLANS

13.26 When an exploding ammunitionship faced South Amboy, N.J., with thesame situation as Texas City, the mayorhad a disaster plan all set to go. Immedi-ately the rescue operation went into highgear.

13.27 Men knew 'where they were sup-posed to go, and they went there. Off-dutypolice were automatically called in. Roadblocks controlled traffic keeping the sight-seers out and letting relief supplies in.Liaison was established, per plan, with theState Police and the National Guard.

13.28 The property destruction atSouth Amboy was nearly as great as atTexas City ($36,000,000) but the loss of lifewas far less (31 dead).

PLANNING PAYS OFF

13.29 In what was termed "the mostsuccessful exercise . . . ever heard of inthe United States", some 200,000 peopleevacuated low lying areas on the Texascoast to avoid hurricane Carla.

13.30 The success and smooth function-ing of this gigantic movement had manyreasons. According to the. Governor ofTexas, "The success of evacuation was theresult of careful planning which began 10years ago in the Governor's office when itsDivision of Defense and Disaster Reliefwas set up." A Red Cross\ official added,it.

. . critics said the Government waspouring money down a rathole (for plan-ning). It wasn'tit was this plan we wereable to use. The State has a CD plan andmade the plan workthat is why we wereable to do so much".

13.31 The head of the Texas Depart-ment of Public Safety, when asked whythe operation had been such a resoundingsuccess, answered, "Why? It was done be-cause of preplanning and training". A'county judge added, "Let people know thevalue of preplanning". In Louisiana, theLake Charles Civil Defense Office statedthat, "The biggest lesson of Carla was that

all of the effort put into some 3 or 4 yearsof intense training and planning paid off.When it was needed, the organization wasready to rollit was only a matter ofcalling the staff togethei and giving themthe job."3

EMERGENCY VERSUS CATASTROPHE

13.32 Despite differences in dictionarydefinitions, often the only real differencebetween an emergency and a catastropheisprior planning.

13.33 Perhaps the best concreteu

exam-ple is the damage control system used byall major modern navies. Naval combatships are not designed from the standpointof wishful thinkingoptimistically hopingthat there will be no hits and do damage.Rather, naval vessels are designed withthe point of view that the ship that cantake the most punishment and still fighton is the ship that will survive and winvictory. Hence, naval combat vessels haveelaborate, but very practical, damagecontrol systems. These systems includewatertight compartments of various sizes,provisions for pumping, for counter-flood-ing to restore balance, of standby andauxiliary power, intensive training and ef-fective organization of the crew, and manyother features. All these are the result ofthe analysis of thousands of accidents atsea, naval engagements, and just plainhard, logical thinking. Thus, when a shipslides down the ways it is the product ofcountless plans, not the last of \which isplanning to keep an emergency from turn-ing into a disaster.

AN IMPORTANT LESSON

13.34 You might well wonder what thepreceding paragraphs have to do with ra-diological defense planning as such. Howdoes the Morro Castle, the Coconut Grove,our Navy's damage control systems, orJohnstown, Pennsylvania, relate to theproblems of planning for civil prepared-ness; what do the explosive qualities ofammonium nitrate have to do with de-

3 Quotes from Department of Defense, Office of Civil Defense,cane Carla. p. 93. Superintendent of Documents, U.S. GovernmentPrinting Office, Washington, D.C.

171

171

fense against or recovery from nuclearattack? The answer is both simple andlogical.

13.35 The cases which have been docu-mented above all serve as illustrations of asingle, vital truth. Name ly,, planning con-sists of a two-pronged approach to a poten-tial problem area which can be summa-rized as:

1. LOGICAL ASSUMPTIONS

2. PRACTICAL ANSWERS

This is no less the case for radiologicaldefense planning than for any other type.The sole purpose of the preceding para-graphs has been to "set the stage".alongthese lines for our consideration ofRADEF planning which will follow.

RADIOLOGICAL DEFENSE PLANNING

13.36 In the previous chapter, we tooka level-by-level look at the operations ofthe RADEF organization from the basicmonitoring station on up to the Stateemergency operating center. We will fol-low this same procedure in this chapterbut, first, some general comments onRADEF planning are in order.

WHERE DOES PLANNING ORIGINATE?

13.37 Though there is obviously a needfor careful planning in RADEF, most peo-ple are aware that this does not meanthese plans can be finalized in Washingtonand shipped out to the States and localcommunities to adopt and put into effect.On the contrary, with a country as diverseas the United States, a plan worked outfor Chicago or New York will not be thesame, indeed should not be the same, as aplan devised for a farm community or aseacoast area. An understanding of thewide diversity of the United States is be-i:ind the establishment of a Federal sys-tem of government by the Founding Fath-ers. They knew that differing situationsrequired different methcds. This is alsotrue in RADEF, for at the various levels ofgovernment, state, county and local, someradiological defense functions are similar,some are materially different and the em-

172

phasis on a given function may appropri-ately vary from level to level.

PLANNING RESPONSIBILITY RESTS ONGOVERNMENT AT ALL LEVELS

13.38 At the community or urban level,detailed and current radiological intelli-gence would be essential for warning anddirecting the protective action to be takenby the local populace as well as for controlof radiation exposure to personnel per-forming locally directed emergency andrecovery functions as called for in thecomplete Civil Preparedness plan.

13.39 At the higher levels of govern-ment, there is increasing responsibility forplanning, coordinating, and, as necessary,directing protective, remedial and recov-ery actions and programs beyond the ca-pabilities of the individual communities.In order to perform such RADEF func-tions within the framework of the overallplan, the State, county or local level needsareawide intelligence which is dependentupon reliable monitoring and reporting.

13.40 Each State has the major respon-sibility for planning, development and im-plementation o' Civil Preparedness pro-grams, and intrastate administration ofFederal assistance for development ofemergency operation capabilities at localto State levels.

13.41 Although the State plan need notpresent complete detail of all purely localradiological defense operations, local capa-bility is a prime requisite for successfulstatewide operations and must be pro-vided for as a part of the more basic Stateplan. Having a State plan is, alone, justnot enough.

NOTE

Don't forget: The primary responsibil-ity for Civil Preparedness planning,and therefore RADEF, rests with theprimary legal authority for whatevergovernment unit is involved.13.42 Once again, planning is the re-

sponsibility of the Coordinator of Civil Pre-paredness at each level. In large or com-plex jurisdictions, a special planninggroup might be established to assist the

_1 7 5

director in making the plan. This specialgroup should work with him (or his dep-uty). The members of such a group gener-ally should be relieved from all, or many,of their other duties to give major timeand attention to planning.

NOTE

When authenticated by the proper offi-cial, acting within the legal purview ofhis authority, the Civil Preparednessoperational plan bears the full force oflaw.

13.43 Remember, a sound planning cy-cle is a continuous planning cycle. Thereare excellent reasons for this.

NO PLAN WILL EVER BE COMPLETE OR

FINAL

13.44 Many wars have been lost be-cause generals learned their lessons toowell and formed their plans too firmly. Thelessons they learned were from the pre-vious war. They analyzed the tactics, theystudied the success and defeats, the ad-vances and retreats. They would nevermake those mistakes. And they never did.They made new mistakes because, whilelearning their lessons, and building planson the basis of those lessons, the worldwas changing. New methods were appear-ing. Thus, the French army in World WarI, learning well the lessons of the previousFranco-Prussian War, determined to at-tack, attack, always attack. Unfortu-nately, the introduction of machine guns,barbed wire, heavy artillery, and othernew weapons gave the advantage to thedefense. When the pride- of France brokeagainst the German defenses in Alsace-Lorraine, the war then passed into aphase dictated not by old plans but by newweapons. Thousands of lives were lost togain a few yards of soil. Any lessons,basedon the early phase of World War I wouldequally have been incorrect during WorldWar II, for the tank, self-propelled artil-lery, and parachute troops gave the initia-tive once again to the attack.

13.45 Yesterday's plans often do not fittoday's problems, and those who will notlift their eyes from the plans to take a

.1 "(4 6

hard look at reality may be doomed to facedisaster.

13.46 Anyone could produce a plan, forexample to counter the Texas City disas-ter now that it is history. The real trickwould have been to plan for it before ithappened as was done in South Amboy.

NOTE

Remember, the difference betweenemergency and castastrophe is plan-ning!

MONITORING STATION PLANNING

13.47 If Mr. Jones, newly appointedRADEF Officer for the town of Anywhere,U.S.A., were to address himself to thequestion of planning for the monitoringnetwork which he feels is necessary tosupport his radiological defense effort, thelogical starting poi,it might well be takenas the determination, in view of popula-tion and geography, of the total number ofradiological monitoring stations he will re-quire. This may be logical but it is alsowrong! The correct starting point wouldbe a careful perusal of RADEF plans al-ready in existence for his city or his coun-try or even his State.

13.48 Every State has an emergency op-erations plan already in existence. Someplans are better than others and, logically,some RADEF annexes to these plans aremore complete than others. But, in anyevent, before Mr. Jones does any planning,he should check to see how much planninghas already been done. If he disagreeswith the plan, he has just discovered hisreal starting point for building up aRADEF capability for the town of Any-where, U.S.A.

13.49 But suppose, for the sake of argu-ment, Mr. Jones found a well-conceivedRADEF annex to his existing area CivilPreparedness plan, one which spelled outrequirements, locations, numbers of mOni-tors and so forth in complete and correctdetail. Suppose, further that he inheriteda going monitor instruction program, hadall the equipment he required and had along waiting list of people begging him fora chance to be radiological monitors. Give

1 73

him hiFr full quota of monitoring stations,all with a protection factor of 100 plustwoway radios as well as telephones.Would it be possible for him to still have amonitoring station problem in the midst ofall this plenty?

13.50 The answer, of course, is yes. Hewould have a very definite problem inspite of all the RADEF assists spelled outabove if he could not point to at least onemore plus feature, that of a functioningprogram of instrument maintenance, re-pair and calibration. His other enviableRADEF assets would not count for muchin an ergency if only, say, 20% of hismonito equipment could be either op-erater&or *ed upon.

SHELTER MONITORING PLANNING

.51 Anywhere, has a suffi-cient 'number of public shelters and themost marginal protection factor in any oneof them is at least 100. Adequate equip-ment is available and already in place ineach shelter to permit it to perform itsself-protecting monitoring function. Mr.Jones was pleased when he learned this,but he was doubly pleased when he alsolearned that there was no personnel re-quirement for monitors, every shelter hadits full quota. Now, perhaps, he can moveto one of his other RADEF problem areas?

13.52 If he does move away from shel-ter monitoring at this point, he could bemaking a very big mistake. The availabil-ity of a facility, the required equipmentand the personnel to operate it are allessential ingredients to a RADEF capabil-ity, true enough, but they are not suffi-cient to guarantee it. A fourth factor isrequired, an all-important factor, and thatis training.

13.53 But let's say that Mr. Jones in-vestigates and finds that his local plancalls for a systematic series of field exer-cises on a regular basis. One exercise se-ries has just concluded and every singlemonitor passed with flying colors. Theydemonstrated a firm grasp of reportingrequirements. Surely, this would indicatethat training is maintained at an ade-quate level.

1 74

1'7.r

13.54 Yes, it does, but only if Mr. Joneswants to ignore the potential need forperforming tasks outside shelters. We canbe reasonably sure he won't, though, be-cause he recognizes there is more to moni-toring than just taking readings and re-porting them. We can rest assured thatour Mr. Jones will see to it that his planprovides for adequate and continuous dis-semination of such important instruction.

EMERGENCY OPERATING CENTERPLANNINGLOCAL AREAS

13.55 By the time he began to review orprepare the portion of the local plan whichdeals with his own EOC, Mr. Jones hadlearned quite a few lessons about not leav-ing anything to chance. He approachedthis task carefully and thoughtfully, mak-ing certain, first of all, that the selectedfacility was adequate both from the stand-point of sufficient space as well as suffi-cient space fo-i. the disrTlayof RADEF data.

13.56 Further, he made sure that therewould be provision for an adequate staff ofplotters and analysts as well as communi-cation personnel. When he realized thatthese people had to be trained, providedwith forms, pencils, paper, pencil sharpe-ners, food, water, etc., etc., he began toworry about the size of the job which facedhim as RADEF Officer.

13.57 One night he sat bolt upright inbed with the shocked realization that al-though he had taken care of all of thesemany items in his EOC planning, he didnot know the protection factor of thebuilding which would house the center!

13.58 He had, he realized, just takenthe appearance of the building at its facevalue and assumed that its protection fac-tor would be satisfactory. He recognizedthe enormity of his mistake immediatelyand lost no time the next day before ask-ing and learning that the protection factorwas more than adequate (much to his re-lief).

13.59 But he did not recognize his realmistake until it was pointed out by hiswife when he told her what had happened,or rather, what could have happened-.

"George," she said, "it's simple. You needan assistant and that's all there is to it!"She was right, of course, because GeorgeJones had made a very human mistake,one which is not confined to the ranks ofRadiological Defense Officers either. Hehad simply failed to notice the point atwhich he was "spreading himself too thin"and his RADEF plan encompassed morearea than one man could handle.

13.60 While in the State capital on abusiness trip, George Jones dropped in onthe State Radiological Defense Officer torenew their acquaintance and in thecourse of their conversation told him howwell Fred Green, the new AssistantRADEF Officer for Anywhere, U.S.A., wasworking out in the job. He mentioned theseries of events which had led to the ap-pointment and was intrigued to hear theexpression, "unmanageable span of con-trol," used in reference to his problem.

13.61 It was an exceptionally apt de-scription, he concluded as he drove homethat evening, and this set him to thinkingin terms of the span of control of his ownlocal RADEF organization. He had dis-cussed "span of control" (although not insuch a precise term) sufficiently with FredGreen to assure himself that it did notrepresent a problem to their organization.As he turned into his driveway, however,he was struck by the sudden thoug:ht thatthis comfortable situation might not betrue of the County Emergency OperatingCenter to which his organization reported.He decided to look into the matter furtherat his earliest opportunity.

13.62 Three months later, the Any-where, U.S.A., Emergency Operating Cen-ter was duly entered in the State CivilDefense Plan and all other supporting doc-

uments. George's suspicion had proved tobe correct, something that the CountyCivil Preparedness Coordinator had beenthinking of himself for soma time. He hadrecognized that the analysis load thrownon his own RADEF organization wouldsimply be too large to handle if an emer-gency should occur during the eveninghours, a time when the bulk of the popula-tion in the county had redistributed itself

into a series of small suburban communi:ties, each with its own little EOC.

13.63. In explaining his situation toGeorge Jones, he ruefully acknowledgedthat all initial planning had been based onthe concept of a daytime emergency andfor many months no one had thought to ex-amine the county RADEF setup in termsof how it would function in the eveninghours. He went on to point out that themistake had been uncovered, interestinglyenough, through the reappraisal of appar-ently inadequate means of alerting certainkey operating personnel during the eve-ning hours. This had led, in turn, to theinteresting discovery that a surprisingnumber of his volunteers had acceptedequivalent assignments in their own homecommunities, some of which were as far astwenty-eight miles away from the countyseat. The County Coordinator acknowl-edged that all of these people had advisedhis office of their decision and, further,that his office had complete records ofthese facts. When his secretary had cas-ually mentioned that they seemed to be infor a rough time if an emergency shouldever start in the evening, though, he sud-denly realized that his fine daytimeRADEF organization would be a desper-ately overworked group if it ever had tocommence functioning during the night.

13.64 As he worked with George Joneson the new plans which called for severalof the newer local EOC's to report to theAnywhere, U.S.A., Area Emergency Oper-ating Center rather than to the CountyEOC, the phrase, "reduce the span of con-trol to manageable proportions," washeard over and over ag:.in because it issuch an apt expression of the purpose ofan area EOC.

13.65 George Jones realized that thework he had done with the County Coordi-nator would be extremely worthwhile forthe county as a whole even though itmeant that his own RADEF organizationwas taking on a substantial added respon-sibility in receiving, analyzing, summariz-ing and reporting the additional datawhich the several local operating centerswould be sending in. In view of thechanged situation, he knew that his own,

175

1

personal span of control and Fred Green'sas well had both been stretched past thedanger point and something would have tobe done about it. He and Fred would haveto review their entire tables of organiza-tion as well as all their initial planningconcepts. Undoubtedly, at least one newassistant would be required, perhaps eventwo. "One thing is certain," thoughtGeorge Jones, "if I have to make mistakesin this RADEF work, at least I'm going tomake new mistakes!"

13.66 The County Coordinator reflectedthat the new plans growing out of hisefforts with George Jones were a big, helpin more ways than one. Now he had moretime to devote to an item which he hadnever felt was all it should be, specifically,the county's radiological monitoring net-work. There was a perfectly adequatenumber and distribution of urban monitor-ing stations, true enough, but he was notcompletely satisfied with his setup in ruraland mobile monitoring. After all, the prob-lems of a county EOC could be consider-ably more complex than those of a localEOC in that county-type RADEF prob-lems had to be approached from the stand-point of area as well as population. Al-though this could be true for a local EOC itwas always true for a county EOC.

13.67 The more he thought about it, themore the County Coordinator was con-vinced that a county EOC was practicallya State EOC on a smaller scale.

13.68 He was certain, for instance, thatthe State Civil Preparedness organizationhad an easier time with maps than he didbecause the Highway Department hadcomplete up-to-the-minute information onevery road in the State, all new construc-tion, road conditions, etc., etc. As a matterof fact, the County Division Office of theHighway Department (which was locatedjust down the hall from his own office) wasthe proud possessor of one of those mastermaps that the State used in its highwaymaintenance and construction program. Itwas a real beauty, showed everything thatanyone could possibly want to know aboutroads in the State. And it was so muchbetter than the maps that he and hismobile monitors were using.. . .

1 76

1 7

13.69 "Just a minute!" he thought,"Why not use that big camera over in ourCounty Records Section and make copiesof their map for ourselves?"

13.70 The more he thought about theidea, the better he liked. it. In the firstplace, there simply wasn't any better mapavailable anywhere, either in or out of theState. Second, he ticked off, it will bemaintained by an outside organizationand every time a major change occurs, anew set of maps can be produced in just avery few minutues. Third, he realized, itwould be an invaluable addition to theresources of his operations center. He de-cided to lose no time in putting his planinto effect.

13.71 When the first copies of the StateHighway Department's map were deliv-ered to his office, the County Coordinatorlost no time in looking them over. Hedecided that the quality of reproductionwas very good, that the maps would fill hisrequirement perfectly. Inspecting themaps a little more closely, he noticed thatthe span of roads which would connectwith the new bridge to be built in a neigh-boring county were just about complete,even though work had not yet begun onthe bridge itself. He was reminded of aconversation he'd had with George Jones afew days before in which George had beentelling him what a boon the new bridgewould be. George, had mentioned that hisdelivery trucks had a choice wheneverthey had a stop to make in the nextcounty. They could drive ten miles upriveron a road that was only fair to get to theclosest bridge or they could drive eighteenmiles downriver on a very good road andmake their crossover there. The newbridge couldn't go up too soon, as far asGeorge Jones was concerned.

13.72 A sudden thought hit the CountyCoordinator.

13.73 He never could think aboutGeorge Jones very much without alsothinking about "span of control" whichalways led him, in turn, to considerGeorge's area EOC and how well the planwas working out in actual practice. Thewords, "area EOC" and the fact that hehad just been thinking about his mobile

monitoring a few seconds before were thetwo things that sparked his idea. Helooked at the map once more. There it was!

13.74 If George Jones' trucks had totravel either ten or eighteen miles to crossthe river, why then so would the mobilemonitoring teams sent out by the CountyCoordinator of the next county!

13.75 "But if the area on our side of theriver were to be monitored by our ownteams," he mused, "then our neighborswouldn't have to make those long tripsjust to get across the river. We're alreadyacross the river as far as they are con-cerned. Why couldn't we take this areaover and monitor it for them? If we didtake over, our crews would be receivingonly a fraction of the radiation exposurewhich their crews would be getting!"

13.76 Little did the County Coordina-tor, realize that his idea would producethe first sub-state EOC in his state and,further, that his own county EOC wouldbecome it! He could see the basic reason-ing behind the move, however, once it hadbeen explained to him because, after all,he would be taking over just about half ofthe area monitoring work of the neighbor-ing county and so might as well take overarea RADEF control as well. He had beena little skeptical about the manpower re-quirements represented by the new re-sponsibility, but was pleasantly surprisedto learn that he would be getting a boostfrom the State EOC in the training ofadditional monitors because the State cen-ter expected to have him take over addi-tional area responsibilities as soon as hewas organized to handle them.

13.77 "One lesson I've learned fromthis," he told George Jones when describ-ing the new RADEF plan to him later on,"is that you never can really forget aboutthat 'span of control' idea that you werethe first to point out to me. Even thoughthis latest move had its beginning ideacompletely outside such a concept, it wasstill a case of reducing the span of controlto manageable proportions, at least so faras the State EOC was concerned."

18u

STATE EMERGENCY OPERATING CENTER

PLANNING

13.78 Some weeks later, the State Ra-diological Defense Officer dropped in onthe County Coordinator to see how his newSubstate EOC planning was shaping up.He was, of course, particularly interestedin any RADEF developments which mightbe of use to him in his role of RADEFadvigor to other EOC's within the State.He didn't really expect to pick up anythingso far as his own operation in the StateEOC was concerned because, after all, ithad been a going concern for at least 2years and a great deal of time and talenthad been devoted to making it so.

13.79 As the County Coordinator wasshowing him the new setup, he noticed twotransparent plastic panels which had beenvertically mounted on sturdy pairs of legs.The panels were pushed back in a cornerout of the way and were apparently with-out any use that he could discover. Heinquired about them.

13.80 "Oh, that's my own, personal lit-tle brain-child," said the County Coordina-tor, "and I don't mind telling you I'm sortof proud of it, too, even though I don'tknow anyone who uses a similar system.You see, I was having some real difficul-ties in the trial runs we had held hereinsofar as using the information we hadplotted and analyzed. There was too muchconfusion in trying to maintain a currentdisplay of the RADEF situation while itwas in use by the director and members ofhis staff.

13.81 "These plastic panels are the an-swer to the problem," he went on. "Tomor-row morning, a man is coming in to paintthe outline of our control area, plus themajor features such as roads, the river,and so forth, on each panel. In an actualexercise, the panels will be out in thecenter of our operating area so that e -er-yone who has to can see them. Our Plot-ters will use grease pencils and, writingbackwards, will spot in exposure informa-tion on one and exposure rate informationon the other. Our Analysts," he continued,."will be in front of the panels and they willalso use grease pencils to draw in contours

177

as well as add any other informationwhich we might need in a graphic form. Ofcourse there are many ways to display thedata and this only represents one way."

13.82 "Say, now," exclaimed the StateRADEF Officer, "this is really something:As a matter of fact, I think I might evenbecome the first official thief of your ideabecause it strikes me as a refinementworth introducing into our. State EOC!You can appreciate how much I need sucha system if you need it to control a piece ofthe total area that I have to worry about.It just goes to show that no plan is everreally final and that includes first of all,our own State Plan."

178

ONE FINAL WORD

13.83 No operations plan, howeversound in concept and complete in detail, isof much value if it is untested or untried.The readiness posture of a plan is meas-ured by its ability to be implemented.Therefore, each operational plan should besubjected to one or more tests as a part ofthe planning cycle. Plan tests should bemade as realistic as possible, and each testshould be evaluated by qualified observersas well as by the participants. Followingthe test, an evaluation report should bemade. The report and evaluation should beused as the basis for revision and the startof a new planning cycle.

181

"PAPER PLANNING" OR REAL RADEF?

To implement the RADEF plan, ofcourse, a variety of elements is required.It is necessary to have equipment and afacility in which to store and use it. thatmuch certainly is obvious. Further, theequipment and the facility cannot do muchby themselves, putting them to use takespeople, sometimes a rather large numberof people, to say nothing of money. And,finally, these people must have some ideaof what they are to do -or &se the equip-ment will remain inert and the facility willbe without purpose. This is just anotherway of saying that RADEF personnel needtraining.

But what should come first, where is thestarting point? How can you tell. when youhave a balanced RADEF team? How do youMaintain a RADEF capability once it is es-tablished? And so forth.

The objective of this chapter, then, is toput these various essentials of an effectiveRADEF plan into their proper perspective... to demonstrate what is necessary tobreathe life into a paper plan and turn itinto an honest-to-goodness RADEE capa-bility.

INTRODUCTION

14.1 We saw in Chapter 13 that planningcan spell the difference between an emer-gency which is promptly dealt with on asystematic basis and, on the other hand,an utter catastrophe. We saw that plan-ning guides us to the best use of all availa-ble resources, and, ultimately, helps savelives. We saw that effective planning re-quires organized, equipped, trained per-sonnel as an essential ingredient. We be-gan to see that all this requires money.

14.2 Now we are ready to break thisplanning ingredient down into its essen-tial parts. These are the basic tools of

182

CHAPTER 14

RADEF planning and an. effectiveRADEF organization. There are four ofthem.

EQUIPMENTFACILITIESPERSONNELTRAINING

We will examine these four items insequence in this chapter. As we do so, itwould be well to remember that theserequirements do not come- from inspira-tions or visions. They come, instead, as aresult of the planning process which is, inturn, a two-step procedure.

14.3 To repeat our summary of thesetwo steps, the first consists of the estab-lishment of some reasonable, sensible,well-thought-out, practical assumptions.The second step is one of -meeting theseassumptions with reasonable, sensible,well-thought-out, practical answers.

EQUIPMENT

14.4 In considering the question of ra-diological instruments and equipment, itimmediately becomes apparent that one ofthe first questions to be answered is,"what kind and how much?" as well as,"where can we get it?"

14.5 To answer the last question first,the Defense Civil Preparedness Agencyhas made radiological equipment availableto the States through their duly consti-tuted Civil Preparedness organizations.This is a "through official channels" typeof exercise and therefore a detailed pres-entation of the fifty different channels isobviously outside the scope of this discus-sion.

14.6 Although a detailed answer to thefirst question in paragraph 14.4 is evenfurther outside our scope, it is neverthe-less possible to demonstrate an importantpoint about RADEF planning in offering a

179

comment on it. Specifically, the answershould lie in your own plan or its RADEFannex and, if it does not, then that plan isdrastically in need of additional work!

14.7 The fact such an answershould be found in an existing plan alsohighlights another feature of planning.The elements of a plan are interdependentand interrelated if the plan is a good one,and further, if any one of these elementsshould change or alter in any way, such achange should be the signal for a reap-praisal and possible revision of the plan.

14.8 In considering equipment require-ments for a particular radiological defensearea, it is important to remember that thisdoes not merely mean operational equip-ment but, in addition, includes trainingequipment. In this regard, an individualresponsible for a DCPA Training SourceSet must hold a Byproduct MaterialUser's Certificate from his respectiveState. And here, incidentally, is furtherproof of the interaction of ostensibly sepa-rate elements in the RADEF plan.

14.9 Not only is the RADEF Officer re-sponsible for obtaining the required opera-tional equipment and making sure thatsufficient training equipment is available,he is also responsible for maintenance. Tothis end, a "chief monitor" -hould be ap-pointed for each monitoring station. Fur-ther, supplementary instruments might bereasonably required and it is up to theRADEF Officer to determine if this is thecase as well as to prepare the necessaryjustification to obtain them.

FACILITIES

14.10 If a RADEF plan is to be capableof execution, there must be a sufficientnumber of radiological monitoring stationsand communications over which they canmake their reports. The RADEF Officer isresponsible for converting a number on apiece of paper (the local area RADEFplan) into a real monitoring and reportingnetwork.

14.11 Since this monitoring and report-ing network will not be worth much with-out a place to receive such reports, thisleads the RADEF Officer next to the facil-

1 80

ity for his local EOC. He must also haveradiological monitoring for communityshelters under close control. While some ofthese community shelters might presum-ably be a part of his regular monitoringnetwork in addition to their mission 0:RADEF protection for the shelter, otherswill not. But in any event he will be re-sponsible for the adequacy of the facilityinsofar as it concerns any aspect ofRADEF,

14.12 Protection factor is, of course, ofparamount importance in determining thesuitability of a RADEF facility and this isanother area for which the RADEF Offi-cer is responsibe. He must assure himselfthat each facility which has been mappedin as a part of the RADEF operation has asufficient protection factor. In addition toprotection factor, an important feature ofsuch facilities will be their ability to fitinto the local communications plan. Inother words, each facility which is selectedand added to the overall RADEF networkmust be capable of carrying out its as-signed function while simultaneously per-forming the vital task of self-protection.

14.13 Before leaving the question of fa-cilities, a word on arrangements for emer-gency food and water for monitoring per-sonnel would be in order.

14.14 Food and water stocks, it could beclaimed, are not really a part of the consid-eration of a facility. It could be arguedequally well that food and water are cer-tainly not radiological "equipment". Thepoint is, however, no matter what label isplaced upon these two commodities, hu-man beings cannot exist or function verylong without either one. Thus it behoovesthe RADEF Officer to make certain thathis facilities have adequate stocks of theseitems.

PERSONNEL

14.15 One of the largest contributingfactors to RADEF personnel requirementsis found in the radiological monitoring net-work.

14.16 Once again, the particular localCivil Preparedness plan or its RADEF an-nex should provide the explicit answer tothis question and,'if it does not, the prob-

183

lem is not one of the monitoring networkbut rather one of completing the plan first.Although the final answer to this questionmust remain a local one to be based uponpopulation, industrial distribution, geog-raphy and the Eke, there are, neverthe-less, certain criteria which can be used.Federal and State governments periodi-cally issue guidelines on the number ofmonitoring stations needed in rural andurban areas.- This information should beconsidered only as a starting point in eval-uating the RADEF monitoring networkrequirements because final answers willalways depend upon the individualities ofthe particular local area in question.

NOTE

Do you think in terms of so many menfor this job, so many men for that one,or so many men in the EOC, and soforth? If you do, then . .

STOP RIGHT NOW!

There are millions of intelligent, sin-cere, capable women in our country.There are undoubtedly thousands inyour own RADEF area. Be sure thatyou remember this in your planningand personnel recruitment activi-ties!!!14.17 As a general rule, RADEF per-

sonnel should be selected primarily fromState and local government employees.This will provide all the advantages ofworking on the basis of an existing organi-zational. framework. For monitors, it issuggested that firemen, State highway pa-trolmen, highway maintenance personnel,their auxiliaries and their reserves be se-lected for training. Further, radiationmonitoring should be included as a part ofthe basic training for all new recruits inthese services and refresher monitortraining should be routinely scheduled forall personnel. To supple ent this initialcadre of monitors, high school and collegescience teachers, selected State, county,and municipal employees in the engineer-ing, sanitation, welfare, and health serv-ices could also be selected for monitortraining.

14.18 In areas where monitoring sta-tions have been established in industrialplants, hospitals, commercial buildings

and other facilities which have an ade-quate protection factor, appropriate per-*sonnel who are normally employed atthese facilities represent another excel-lent source of monitors.

14.19 In rural and suburban areaswhere a home shelter may have been des-ignated as a part of the monitoring andreporting system, members of the familywho will occupy the shelter should, if pos-sible, be recruited as a part of the RADEForganization.

14.20 Once again, since a large cadre ofmonitors will be needed, the selection ofpersonnel for training should be. fairlybroad. Remember that women, as well asmen, can perform a very significant role inmonitoring, and certainly should not beoverlooked in any recruitment effort.

14.21 For decontamination training, se-lection of key personnel should be primar-ily among the fire, sanitation, public worksand engineering services. However, selec-tion should alsobe extended to those per-sonnel who operate street sweeping andflushing equipment, road graders, scrap-ers, and earth moving and demolitionequipment. Selection of such key person-nel will be from State, county, and munici-pal employees, but should also be extendedto others such as highway constructioncontractors, since most of the equipmentneeded for decontamination work will befound in these areas to say nothing of aready source of personnel trained in itsuse.

TRAINING14.22 There are two basic areas of

training, the training of monitors and thetraining of the RADEF staff. The latter isof particular importance for it is impera-tive that the leadership staff be providedin order to form a seed-bed for providingfurther training to other personnel.

RADEF OFFICER AND RADIOLOGICALMONITORING FOR INSTRUCTORSTRAINING

14.23 Local and State jurisdictionshave the responsibility for obtainingtrained Radiological Defense Officers.

184181

Upon completion of his training, theRADEF Officer provides instruction to thepeople who have been selected for hisRADEF staff and the monitors needed inhis community.

14.24 Be sure you don't overlook theresource represented by the capabilitiesexistent in the Armed Forces to supple-ment monitor training resources.

14.25 As monitors are trained, theRADEF Officer should assign them to aspecific monitoring station for operationalpUrposes. Generally, monitors should beassigned to facilities which are near wherethey normally work or reside. Each moni-tor will be ordered to report to his desig-nated shelter or monitoring station in anemergency. All monitors should be in-structed to find some shelter in the eventthey cannot reach their assigned station.In addition, provision must be 'made forthe families of monitors, both as a moralefactor and also by way of avoiding possibleconfusion during an emergency.

14.26 Upon completion of his training,each monitor will be furnished a HAND-BOOK FOR RADIOLOGICAL MONI-TORS, FCDG-E-5.9 containing detailed in-structions for monitoring and reportingoperations as well as special instructionsconcerning his responsibilities for dealingwith routine and emergency radiation con-ditions. DCPA will provide these manualsfor distribution to the monitors.

14.27 Continuing training of monitorsto provide for personnel attrition and re-fresher training of monitorston an annualto 6 months basis should be arranged forby the local RADEF Officer.

14.28 The following paragraphs providea summary of some important points forpersons concerned with establishingRADEF training programs, either for ra-diological mor :..1rs or for the RADEFstaff.

TRAINING REQUIREMENTS

14.29 The first step is to find out whatwe need in the way of training. We must182

determine how many monitors we need. Todo this it is necessary to analyze the localRADEF ,plan since training requirementswill stem from the assessment containedin the plan. (If no plan is available, oneshould be developed first.)

RECRUITMENT OF RADEF PERSONNEL .

14.30 After we have found how manytrained personnel are needed, it will benecessary to recruit the manpower fortraining. By far the best sources will befull-time municipal, county and State em-ployees. Since they are also one of the bestsources for Civil Preparedness personnelother than RADEF, coordination will benecessary to avoid conflicting assign-ments. Another possible difficulty is thatRADEF activities have no exact counter-part in existing governments.. In other?,words, the Civil Preparedness plan whichfits the police force into the law and orderrole or the sanitation department into thedecontamination role during an emer-gency will not find a ready-made govern-mental activity which fits RADEF activi-ties.

NOTE

It is important, both for motivationand realism in training, that the stu-dent have an assignment based on theRADEF plan BEFORE he beginsto undergo training.

TRAINING LOCATION

14.31 The courses should be taught inlocations convenient for the studentssince many will presumably be volunteers,it is doubly important that all impedi-ments to training, such as distant placesand inflexible or inconvenient class hours,be removed. If on-the-job training can bearranged with local government authori-ties, this will materially aid in the rapidtraining of monitors and others.

18

TRAINING LOGISTICS14.32 It is important that training

equipment be ordered at the earliest mo-ment after training requirements are de-termined, and that the necessary user per-mits needed for handling Training SourceSets be applied for. The Defense Civil Pre-paredness Agency provides a "Radiologi-cal Monitoring Training Package," K-24which includes an Instructor Guide, andsupporting visual aid material. This, too,should be obtained without delay and insufficient quantity.

TRAINING ASSISTANCE

14.33 It is vital that liaison be estab-lished with all agencies, public and pri-vate, that can offer assistance in teachingor recruitment. Whatever instructor capa-bilities already exist on the local levelshould be appraised and utilized. Find outfrom the already existing Civil Prepared-ness organization what is available. Othercities in your area may have a fully func-tioning organization with a number ofqualified instructors. There's no advan-tage in "going it alone" so, if you can gethelp from outside your immediate jurisdic-tion, don't hesitate to take it. After all,fallout will not recognize any boundaries.

TRAINING METHODS

14.34 As we have seen, we are nottraining just for training's sake nor are wetraining to increase theoretical or aca-demic knowledge. We are training for spe-cific jobs. Hence, the selection of coursecontent material should aim at:

training to do a particular jobtraining to instill desirable habitstraining to enhance operational knowl-edge

To achieve these ends, course materialshould stress student participation. Pas-sive lecture methods should be avoided infavor of the active approach featuringdemonstration, exercises, laboratory, andquestion and answer methods. Teachingaids, models, slides, films, vugraphs, flan-nel boards, and other visual aids should beused when they support learning as an

end in themselves. Incidentally, one of themost important things to do when usingsuch equipment is to check it out in ad- __vance; be sure it works, and that you knowhow to use it.

TRAINING EVALUATION

14.35 It is'important that there be fre-quent tests of skills learned in the trainingcourses. Such evaluation should be on pro-ficiencythrough demonstrationratherthan student reproduction of academic ortheoretical knowledge. Make it realisticshould be the guide to effective trainingand evaluation of such training.

NOTE

The best things in life may be free, butbuilding and training a RADEF or-ganization is not! At any level of gov-ernment, there is a requirement ofbudgeting for RADEF. DON'T FOR-GET TO PUT RADEF IN THEBUDGET!

A BIRD'S-EYE VIEW OF RADEF

14.36 It's no secret to anyone who hashad any contact with radiological defensethat, as a subject, it is technical and it iscomplex. Although a single individual as-signment can be presented in a relativelysimple, straightforward manner, the sumof all such assignments covers a very widerange of knowledge and presents a rathercomplicated picture.

14.37 This situation leads us to a singlesimple question, "Who will tie all theseloose ends together?". We have radiologi-cal instruments, monitoring stations, shel-

. ter radiological requirements, trainingsource sets, data to be plotted, curves to bedrawn, reports to be received, reports tobe sent, the list is literally endless and yetsome sort of knowledgeable coordinationmust take place between ail these facetsand elements and bits and pieces.

14.38 For the sake of argument, let'sconsider what would be necessary if wewere to decide to go into a manufacturingbusiness. Let's for example, make it furni-ture manufacturing. Immediately we real-ize that we need someone who knowssomething about building furniture. This

183

186'

leads us to a conclusion that he shouldalso know something about the wood andother materials which will be required,where to find them and how to use them.He must be aware. of the availability anduses of a whole variety of special tools.And he must know a great deal more aswell. We are aware of how foolish wewould be to hire cabinet makers, salesmen,clerks, and so forth until we were certainwe had our man who knew the furnituremanufacturing business. This example isso obvious it's almost ridiculous, isn't it?

14.39 But it is not ridiculous when theradiological defense parallel is drawn be-cause it is surprisingly easy to becomebogged down in the many technical consid-erations of RADEF work and, as a result,lose sight of a basic fact. That fact is:

Monitors, facilities, instructors, in-struments, communications, decon-tamination teams, RADEF plans andall' the rest of it do not constitute aradiological defense capability .

unless . .

RADIOLOGICAL DEFENSE OFFICERS

are available to tie the package to-gether into the real countermeasurefor survival that RADEF is meant tobe.

Just as most other facts can be ex-pressed in corollary terms, this onecan be ,given such expression withequal ease. The corollary is:

Provided that there are sufficientRADIOLOGICAL DEFENSE OFFICERS

available, a radiological defense capa-bility is in process of building, regard-less of inadequacies in any otherRADEF area.14.40 These facts can be expressed on a

national scale as well as a purely local oneOur national RADEF capability requiresfacilities, monitors, instruments and manyother elements of survival in the nuclearage . . . and must include a cadre of capa-ble, trained Radiological Defense Officers.With such a group, we can have a nationalRADEF capability but without it, never.

184

RADEF OFFICERS ARE MADE, NOT BORN!

14.41 There is no such thing as beingappointed an expert on any given subjectand radiological defense is no differentfrom any other subject in this regard. Theonly road to becoming a Radiological De-fense Officer is study and training.

14.42 But what about Joe Smith whohas just received his doctorate in, of allthings, nuclear physics? Can't we at leastrecognize 'him as a Radiological DefenseOfficer because of his provable knowledgeof atomic structure, fission, radiation, cur-ies and things like that?

14.43 No, we cannot recognize DoctorJoe Smith, nuclear physicist, as a Radiol-ogical Defense Officer unless he has beentrained as a Radiological Defense Officer.

14.44 The point may seem obvious butit is nevertheless very well taken. Cer-tainly there is nothing wrong with havinga RADEF Officer who is also a nuclearphysicist, no more so than there is any-thing wrong with having one who is a sci-ence instructor, industrial scientist, or anengineer, but none of these individuals willbe a RADEF Officer until he has actuallybeen trained as such.

14.45 Along these general lines, it is agood idea to remember that the DCPAcourses which lead up to qualifying as aRADEF Officer have been developed with aview toward providing the technical infor-mation which will be required to do the job.The individual is, of course, expected tocarry out a certain amount of independentstudy as well as keep himself up to date onthe subject through continuing closecontact via the channels of his own CivilPreparedness organization.

IMPORTANT

Our nation needs thousands of capa-ble, trained RADEF Officers . . . In-structors can and will provide thetraining . . . the individual, however,must provide the capability!

GLOSSARY '1

A

ABSORBED DOSE: see DOSE.

AFTERWINDS: Wind currents set up inthe vicinity of a nuclear explosion di-rected toward the burst center, result-ing from the updraft accompanying therise of the fireball.

AIR BURST: The explosion of a nuclearweapon at such a height that the ex-panding fireball does not touch theearth's surface when the luminosity is amaximum (in the second pulse).

ALPHA PARTICLE: A particle emittedspontaneously from the nuclei of someradioactive elements. It is identical witha helium nucleus, having a mass of fourunits and an electric charge of two posi-tive units. See Radioactivity.

AMBIENT: Going or moving around; alsoenclosing encompassing.

ATOM: The smallest (or ultimate) particleof an element that still retains the char-acteristics of that element. Every atomconsists of a positively charged centralnucleus, which carries nearly all themass of the atom, surrounded by a num-ber of negatively charged electrons, sothat the whole system is electricallyneutral. See Element, Electron, Nucleus.

ATOMIC BOMB (OR WEAPON): A termsometimes applied to a nuclear weaponutilizing fission energy only. See Fis-sion, Nuclear Weapon.

ATOMIC CLOUD: See Radioactive Cloud.

ATOMIC NUMBER: See Nucleus.

I When passible, definitions have been reprinted from the glossary ofThe Effects orguelear Weapons, February 1061.

GLOSSARY

ATOMIC WEIGHT: The relative weight ofan atom of the given element. As a basisof reference, the atomic weight of thecommon isotope of carbon (carbon 12) istaken to be exactly 12; the atomicweight of hydrogen (the lightest ele-ment) is then 1.008. Hence, the atomicweight of any element is approximatelythe weight of an atom of that elementrelative to the weight of a hydrogenatom.

AVALANCHE EFFECT: The multiplica-tive process in which a single chargedparticle accelerated by a strong electricfield produces additional charged parti-cles through collision with neutral gasmolecules. This cumulative increase ofions is also known as Townsend ioniza-tion or a Townsend avalanche. Ava-lanche occurs in the Geiger tube of a CDV-700.

B

BACKGROUND RADIATION: Nuclear (orionizing) radiations arising from withinthe body and from the surroundings towhich individuals are always exposed.The main sources of the natural back-ground radiation are potassium-40 inthe body, potassium-40 and thorium,uranium, and their decay products (in-cluding radium) present in rocks, andcosmic rays.

BARRIER SHIELDING: Shielding gainedby interposing a physical barrier be-tween a given point and radiationsource.

BETA PARTICLE: A charged particle ofvery small mass emitted spontaneouslyfrom the nuclei of certain radioactiveelements. Most (if not all) of the direct

185

188

fission products emit (negative) betaparticles. Physically, the beta particle isidentical with an electron moving athigh velocity. See Electron, FissionProducts, Radioactivity.

BINDING ENERGY: The tremendous en-ergy which holds the neutrons and pro-tons of an atomic nucleus together.

BIOLOGICAL DOSE: See Dose.

BLAST WAVE: A pulse of air in which thepressure increases sharply at the front,accompanied by winds, propagated coriLtinuously from an explosion. See ShockWave.

BODY BURDEN: The amount of radioac-tive material in the body at a giventime.

C

CALIBRATION: Determination of varia-tion in accuracy of radiological instru-ments. Radioactive sources are used toproduce known exposure rates at speci-fied distances. The variation in accuracyof a radiological instrument can be de-termined by comparing it with theseknown exposure rates.

CHAIN. REACTION: When a fissionablenucleus is split by a neutron it releasesenergy and one or more neutrons. Thesein turn split more fissionable-nuclei re-

;

leasing more energy and neutrons, thusmaki ng- --themaking-the-proces& a self-sustainingchain reaction.

CHROMOSOME: One of the particles intowhich a portion of the cell nucleus splitsup prior to cell division: assumed to bedeterminants of species and of sex.

CLEAN WEAPON: One in which meas-ures have been taken to reduce theamount of residual radioactivity rela-tive to a "normal" weapon of the sameenergy yield.

COMPTON EFFECT: The scattering ofphotons (of gamma or X-rays) by theorbital electrons of atoms. In a collisionbetween a (primary) photon and an elec-tron, some of the energy of the photon istransferred to the electron which is gen-

1 86

18

erally ejected from the atom. Another(secondary) photon, with less energy,then moves off in a new direction at anangle to the direction of motion of theprimary photon.

CONTAINED UNDERGROUND BURST:An underground detonation at such adepth that none of the radioactive resi-dues escape through the surface of theground.

CONTAMINATION: The deposit of radio-active material on the surfaces of struc-tures, areas, objects, or personnel, fol-lowing a nuclear explosion. This mate-rial generally consists of fallout. inwhich fission products and otherweapon debris have become incorpo-rated with particles of dirt, etc. Contam-ination can also arise from the radioac-tivity induced in certain substances bythe action of neutrons from a nuclearexplosion. See Decontainination, Fal-lout, Induced Radioactivity, Weapon De-bris.

CONTAMINATION CONTROL: Action toprevent the spread of fallout and reducecontamination of people, areas, equip-ment, food and water.

COSMIC RAYS: Very high energy particu-late (particles)- and electromagnetic(rays) radiations which originate out inspace and constantly bombard theearth.

CRITICAL MASS: The minimum mass ofa fissionable material that will justmaintain a fission chain reaction underprecisely specified conditions, such asthe nature of the material and its pu-rity, the nature and thickness of thetamper (or neutron reflector), the den-sity (or compression), and the physicalshape (or geometry). For an explosion tooccur, the system must be supercritical,i.e., the mass of material must exceedthe critical mass under the existingconditions. See Supercritical.

CURIE (Ci): A unit of radioactivity; it isthe- quantity of any radioactive speciesin which 3.700 x 10I° nuclear disintegra-tions occur per second. The GAMMA

CURIE is sometimes defined corre-spondingly as the quantity of materialin which this number of gamma-ray pho-tons are emitted per second.

CYCLOTRON: An apparatus which ob-tains high-energy electrically chargedparticles by whirling them at immensespeeds in a strong magnetic field; usedespecially to create artificial radioactiv-ity; an atom smasher. ,

D

DAUGHTER PRODUCT: The product (dif-ferent element) formed when a radioac-tive material decays. Some radioactiveelements will form many daughter prod-ucts during their decay to a stable state.

DECAY (OR RADIOACTIVE DECAY):The decrease in activity of any radioac-tive material with the passage of time,due to the spontaneous emission fromthe-atomic nuclei of either alpha or betaparticles, sometimes accompanied bygamma radiation. See Half-Life, Radio-activity.

DECONTAMINATION: The reduction orremoval of contaminating radioactiven#tterial from a structure, area, object,Of person. Decontamination may be ac-qmplished by (1) treating the surface soas to remove or decrease the contarnina -.tion; (2) letting the material stand sothat the radioactivity is decreased as aresult of natural decay; and (3) coveringthe contamination.

DEUTERIUM-. An isotope of hydrogen ofmass 2 units; it is sometimes referred toas heavy hydrogen. It can be used inthermonuclear fusion reactions for therelease of energy. Deuterium is ex-tracted from water which always con-tains 1 atom of deuterium to about 6,500atoms of ordinary (light) hydrogen. SeeFusion, Thermonuclear.

DIRTY WEAPON: One which produces alarger amount of radioactive residuesthan a "normal" weapon of the sameyield.

1 u

DOSE A (total or accumulated) quantityof ionizing (or nuclear) radiation. Theterm dose can be used in the sense ofthe exposure dose, expressed in roent-gens, which is a measure of the totalamount of ionization that the quantityof radiation could produce in air. Thisshould be distinguished from the ab-sorbed dose, given in reps or rads, whichrepresent the energy absorbed from theradiation per gram of specified body tis-sue. Further, the biological dose, inrems, is a measure of the biological ef-fectiveness of the radiation exposure.See RAD, REM, REP, Roentgen.

DOSE RATE '; As a general rule, theamount of ionizing (or nuclear) radia-tion to which an individual would beexposed or which he would receive perunit of time. It is usually expressed asroentgens, rads, or rems per hour or inmultiples or submultiples of these units,such as milliroentgens per hour. Thedose rate is commonly used to indicatethe level of radioactivity in a contami-nated area.

DOSIMETER: An instrument for measur-ing and registering total accumulatedexposure to ionizing radiations.

DRAG LOADING: The force on an objector structure due to the transient ,windsaccompanying the passage of a blastwave. The drag pressure is the productof the dynamic pressure and the dragcoefficient which is dependent upon theshape (or geometry) of the structure orobject. See Dynamic,Pressure.

DYNAMIC PRESSURE: The air pressurewhich results from the mass air flow (orwind) behind the shock front of a blastwave. It is equal to the product of halfthe density of the' air through which theblast wave passes and the square ortheparticle (or wind) velocity behind theshock front as it impinges on the objector structure.

In this revised text, "exposure" and "exposuiv rate" have been sub-stituted for "dose" and "dose rate" in those instances where the meas-urement is explicitly or implied in roentgen units. Dose and dose ratehave been retained where the meaning is an absorbed quantity or ratein rad or rem units.

187

E

EARLY FALLOUT: See Fallout.

ELECTROMAGNETIC PULSE (EMP):Energy radiated by a nuclear detona-tion in the medium-to-low frequencyrange that may affect or damage electri-cal or electronic components and equip-ment.

ELECTROMAGNETIC RADIATION: Atraveling wave motion resulting fromoscillating magnetic and electric fields.Familiar electromagnetic radiationsrange from X-rays (and gamma rays) ofshort wavelength, through the ultravi-olet, visible, and infrared regions, to ra-dar and radio waves of relatively longwavelength. All electromagnetic radia-tions travel in a vacuum with the veloc-ity of light. See Photon.

ELECTRON: A particle of very smallmass, carrying a unit negative or posi-tive charge. Negative electrons, sur-rounding the nucleus, are present in allatoms; their number is equal to thenumber of positive charges (or protons)in the particular nucleus. The term elec-tron, where used alone, commonly refersto these negative electrons. A positiveelectron is usually called a positron, anda negative electron is sometimes calleda negatron. See Beta Particle.

ELECTRON VOLT (eV): The energy im-parted to an electron when it is movedthrough a potential difference of 1 volt.It is equivalent to 1.6 x 10'2 erg.

ELEMENT: One of the distinct, basic vari-eties of matter occuring in naturewhich, individually or in combination,compose substances of all kinds. Approx-imately ninety different elements areknown to exist in nature and severalothers, including plutonium, have beenobtained as a result of nuclear reactionswith these elements.

EMERGENCY OPERATING CENTER(EOC): The protected site from whichcivil government officials exercise direc-tion and control in an emergency.

ENERGY: Capacity for performing work.

1 88

EPIDERMIS: The outer skin.EPILATION: Loss of hair.

ERG: A unit of energy or work. An erg isthe energy required for an electron toionize about 20 billion molecules of air.

ERYTHEMA: A superficial skin diseasecharacterized by abnormal redness, butwithout swelling or fever.

EXCITATION: The raising or transfer-ring of an atom from its normal energylevel to a higher energy level.

EXPOSURE CONTROL: Procedurestaken to keep, radiation exposures ofindividuals or groups from exceeding arecommended level, such as keeping out-side missions as short as possible.

EXPOSURE: See Dose.

EXPOSURE RATE: See Dose Rate.

FALLOUT: The process or phenomenon ofthe fallback to the earth's surface ofparticles contaminated with radioactivematerial from the radioactive cloud. Theterm is also applied in a collective senseto the contaminated particulate matteritself. The early (or local) fallout is de-fined, somewhat arbitrarily, as thoseparticles which reach the earth within24 hours after a nuclear explosion. Thedelayed (or worldwide) fallout consists ofthe smaller particles which ascend intothe upper troposphere and into thestratosphere and are carried by winds toall parts of the earth. The delayed fal-lout is brought to earth, mainly by rainand snow, 'over extended periods rang-ing from months to years.

FALLOUT MONITORING STATION: Adesignated facility for the collection ofradiological data by trained and assignedmonitors using instruments stored orassigned to that location. It should havegood fallout protection and relativelyreliable communications. Examplesmight be a fire station, police or publicworks building, public fallout shelter,etc.

19i

FILM BADGE: A small metal or plasticframe, in the form of a badge, worn bypersonnel, and containing X-ray (or sim-ilar photographic) film for estimatingthe total amount of ionizing (or nuclear)radiation to Which an individual hasbeen exposed.

FIREBALL: The luminous sphere of hotgases which form a few millionths of asecond after a nuclear explosion as theresult of the absorption by the sur-rounding medium of the thermal X-raysemitted by the extremely hot (severaltens of millions degrees) weapon resi-dues. The exterior of the fireball in aidsinitially sharply defined by the luni;i-nous shock front and later by the limitsof the hot gases themselves (radiationfront).

FIRE STORM: Stationary mass fire, gen-erally in built-up urban areas, generat-ing strong, inrushing winds from all si-des; the winds keep the fires fromspreading while adding fresh oxygen toincrease their intensity.

FISSION: The process whereby the nu-cleus of a particular heavy elementsplits into (generally) two nuclei oflighter elements, with the release ofsubstantial amounts of energy. Themost important fissionable materialsare uranium 235 and plutonium 239.

FISSION FRACTION: The fraction (orpercentage) of the total yield of a nu-clear weapon which is due to fission. Forthermonuclear weapons the averagevalue of the fission fraction is about 50percent.,

FISSION PRODUCTS: A general term forthe complex mixture of substances pro-duced as a result of nuclear fission. Adistinction should be made betweenthese and the direct fission products orfission fragments which are formed bythe actual splitting of the heavy-ele-ment nuclei. Something like 80 differentfission fragments result from roughly 40different modes of fission of a givennuclear species, e.g., uranium 235 or plu-tonium 239. The fission fragments, beingradioactive, immediately begin to decay,

forming additional (daughter) products,with the result that the complex mix-ture of fission products so formed con-tains about 200 different isotopes of 36elements.

FLASH BURN: A burn caused by exces-sive exposure (of bare skin) to thermalradiation. See Thermal Radiation.

FRACTIONATION: Any one of severalprocesses, apart from radioactive decay,which results in change in the composi-ton of the radioactive weapon debris.As a result of fractionation, the delayedfallout generally contains relativelymore of strontium 90 and cesium 137,which have gaseous precursors, thandoes the early fallout from a surfaceburst.

FREE AIR OVERPRESSURE (OR FREEFIELD OVERPRESSURE): The unre-flected pressure, in excess of the am-bient atmospheric pressure, created inthe air by the blast wave from an explo-sion.

FUSION: The process whereby the nucleiof light elements, especially those of theisotopes of hydrogen, namely, deuteriumand tritium, combine to form the nu-cleus of a heavier element with the re-lease of substantial amounts of energy.See Thermonuclear.

G

GAMMA RAYS (OR RADIATIONS): Elec-tromagnetic radiations of high energyoriginating in atomic nuclei and accom-panying many nuclear reactions, e.g.,fission, radioactivity, and neutron cap-ture. Physically, gamma rays are identi-cal with X-rays of high energy, the onlyessential difference being that the X-rays do not originate from atomic nuclei,but are produced in other ways, e.g., byslowing down (fast) electrons of highenergy. See Electromagnetic Radiation,X-Rays.

GEIGER COUNTER: An electrical devicewhich can be used for detecting andmeasuring relatively low levels of nu-clear radiation.

189

tr

GENETICEFFECT: The effect (of nuclearradiation, in particular) of producingchanges (mutations) in the hereditarycomponents (genes) in the germ ,cellspresent in the reproductive organs (gon-ads). A mutant gene causes changes inthe next generation which may or maynot be apparent.

GEOMETRY SHIELDING: Shieldinggained by distance from the source ofradiation..

GRAM: A unit of mass and weight in themetric system equal to approximatelyone-thirtieth of an ounce.

GROUND ZERO: The point on the surfaceof land or water vertically below orabove the center of a burst of a nuclear(or atomic) weapon; frequently abbrevi-ated to GZ. For a burst over or underwater, the term surface zero shouldpreferably be used.

GUN-TYPE WEAPON: A device in whichtwo or more pieces of fissionable mate-rial, each less than a critical mass, arebrought together very rapidly so as toform a supercritical mass which can ex-plode as the result of a rapidly expand-ing fission chain.

H

HALF-LIFE: The time required for theactivity of a given radioactive species todecrease to half )f its initial value dueto radioactive decay. The half-life is acharacteriStic property of each radioac-tive species and is independent of itsamount or condition. The effective half-life of a given isotope is the time inwhich the-quantity in the body will de-crease to half as a result of both radioac-tive decay and biological eliminatiOn.

HALF-VALUE THICKNESS: The thick-ness of a given material which,t,will ab-sorb half the gamma radiation incidentupon it. This thickness depends on thenature of the materialit is roughlyinversely proportional to its densityand also on the energy of the gammarays.

HALOGEN: The family of elements con-

190

taining fluorine, chlorine, bromine, io-dine and astatine.

HEAVY HYDROGEN: See Deuterium.

HEAVY WATER: Water containing heavyhydrogen (deuterium) atoms in place ofthe normal hydrogen atoms.

HIGH-ALTITUDE BURST: This is de-fined, somewhat arbitrarily, as a deto-nation at an altitude over 100,000 feet.Above this level the distribution of theenergy of the explosion between blastand thermal radiation changes appreci-ably with increasing altitude due tochanges in the fireball phenomena.

HOT SPOT: Region in a contaminatedarea in which the level of radioactivecontamination is somewhat greaterthan in neighboring regions in the area.See Contamination.

HYDROGEN BOMB (OR WEAPON): Aterm sometimes applied to nuclearweapons in which part of the explosiveenergy is obtained from nuclear fusion(or thermonuclear) reactions. See Fu-sion, Nuclear Weapon, Thermonuclear.

IMPLOSION WEAPON: A device in whicha quantity of fissionable material, lessthan a critical mass, has its volume sud-denly decreased by -2o,npression, so thatit becomes supercritical and an explo-sion can take place. The compression isachieved by means of a spherical ar-rangement of specially fabricatedshapes of ordinary high explosive whichproduce an inwardly directed implosionwave, the fissionable material being atthe center of the sphere. See Supercriti-cal.

INDUCED RADIOACTIVITY: Radioactiv-ity produced in certain materials as aresult of nuclear reactions, particularlythe capture of neutrons, which are ac-companied by the formation of unstable(radioactive) nuclei. The activity in-duced by neutrons from a nuclear (oratomic) explosion in materials contain-ing-the elements sodium, manganese,silicon, or aluminum may be significant.

193

INFRARED: Electromagnetic radiationsof wavelength between the longest visi-ble red (7,000 Angstroms or 7 x 10-1millimeter) and about 1 millimeter. SeeElectromagnetic Radiation.

INITIAL NUCLEAR RADIATION: Nu-clear radiation (essentially neutronsand gamma rays) emitted from the fire-ball and the cloud column during thefirst minute after a nuclear (or atomic)explosion.' The time limit of one minuteis set, somewhat arbitrarily, as that re-quired for the source of part of the ra-diations (fission products, etc., in theradioactive cloud) to attain such aheight that only insignificant amountsreach the earth's surface. See ResidualNuclear Radiation.

INTENSITY: The energy (of any radia-tion) incident upon (or flowing through)unit area, perpendicular to the radiationbeam, in unit time. The intensity ofthermal radiation is generally expressedin calories per square centimeter persecond falling on a given surface at anyspecified instant. As applied to nuclearradiation, the term intensity is some-times used, rather loosely, to expressthe exposure rate at a giver. location,e.g, in roentgens (or milliroentgens) perhour.

INTERNAL RADIATION:' Nuclear radia-tion (alpha and beta particles andgamma radiation) resulting from radio-active substances in the body. Impor-tant sources are iodine 131 in the thy-roid gland, and strontium 90 and pluton-ium 239 in the bone.

INVERSE SQUARE LAW: The law whichstates that when radiation (thermal ornuclear) from a point source is emitteduniformly in all directions, the amountreceived per unit area at any given dis-tance from the source, assuming no ab-sorption, is inversely proportional to thesquare of that distance.

IONIZATION: The separation of a nor-mally electrically neutral atom or mole-cule into electrically charged compo-

.nents. The term is also employed to de-scribe the degree or extent to which this

, separation occurs. In the sense used inthis book, ionization refers especially tothe removal of an electron (negativecharge) from the atom or molecule,either directly or indirectly, leaving apositively charged ion. The separatedelectron and ion are referred to as anion pair. See Ionizing Radiation.

ION PAIR: See Ionization.IONIZING RADIATION: Electromagnetic

radiatic.. (gamma rays%.or X-rays) orparticulate radiation (alpha particles,beta particles, neutrons, etc.); capable orproducing ions, i.e., electrically chargedparticles, directly or indirectly, in itspassage through matter.

ISOCROME: A line connecting thosepoints on the earth at which falloutfrom any one weapon is forecast toreach the surface at the same time.

ISOTOPES: Forms of the same elementhaving identical chemical properties butdiffering in their atomic masses (due todifferent numbers of neutrons in theirrespective nuclei) and in their nuclearproperties, e.g., radioactivity, fission,etc. For example, hydrogen has threeisotopes, with masses of 1 (hydrogen), 2(deuterium), and 3 (tritium) units, respec-tively. The first two of these are stable(nonradioactive), but the third (tritium)is a radioactive isotope. Both of the com-mon isotopes of uranium, with masses of235 and 238 units, respectively, are ra-dioactive, emitting alpha particles, buttheir half-lives are different. Further-more, uranium 235 is fissionable by neu-trons of all energies, but uranium 238will undergo fission only with neutronsof high energy. See Nucleits.

J

(None)

KILO-ELECTRON VOLT (keV): Anamount of energy equal to 1,000 electronvolts. See Electron Volt.

KILOTON ENERGY (KT): The energy of anuclear (or atomic) explosion which isequivalent to that produced by the ex-

191

19,1

plosion of 1 kiloton (i.e., 1,000 tons) ofTNT, i.e., 10'2 calories of 4.2 x10'9 ergs.See Megaton Energy, TNT Equivalent.

LD/50 or LD-50 or LD,: Abbreviations formedian lethal dose. See Median LethalDose.

M

MACH EFFECT: See Mach Stem._MACH STEM: The shock front formed by

the fusion of the incident and reflectedshock fronts from an explosion. Theterm is generally used with reference toa blast wave, propagated in the air, re-flected at the surface of the earth. TheMach stem is nearly perpendicular tothe reflecting surface and presents aslightly convex (forward) front. TheMach stem is also called the Mach front.

MALAISE: Uneasiness. Discomfort.MASS: A measure of the quantity of mat-

ter. The material equivalent of energy.Mass and energy are different forms ofthe same thing.

MASS NUMBER: See Nucleus.MEDIAN LETHAL DOSE: The amount of

ionizing (or nuclear) radiation exposureover the whole body which, it is ex-pected, would be fatal to 50 percent of alarge group of living creatures or orga-nisms. It is commonly (although not uni-versally) accepted that about 450 roent-gens, received over the whole body inthe course of a few days or less, is themedian lethal dose for human beings.

MEGACURIE: One million curies. SeeCurie.

MEGATON ENERGY (MT): The energyof a nuclear explosion which is equiva-lent to 1,000,000 tons (or 1,000 kilo-tons)of TNT, i.e., 10'3 calories or 4.2 x 1022 egs.See TNT Equivalent.

MEV (MeV): Million electron volts, a unitof energy commonly used in nuclearphysics. It is equivalent to 1.6 x10-6 erg.Approximately 200 MeV of energy areproduced for every nucleus that under-goes fission. See Electron Volt.

192

MICROCURIE: A one-millionth part of acurie. See Curie.

MICRON: A one-millionth part of a meter,i.e., 10-6 meter or 10-4 centimeter; it isroughly four one-hundred-thousandths(4 x10-'5) of an inch.

MICROSECOND: A one-millionth part of asecond.

MILLICURIE (mCi): A one-thousandthpart of a curie.

MILLIREM: A one-thousandth part of arem.

MILLIROENTGEN (mR): A one-thou-sandth part of a roentgen.

MILLISECOND: A one-thousandth partof, a second.

MITOSIS: The process by which livingcells multiply in the body by splitting orfissioning.

MOLECULE: The smallest unit of a chem-ical compound. For example a moleculeof water consists of two hydrogen atomscombined with one atom of oxygen(H0), and a molecule of sugar consistsof a combination of twelve carbon at-oms, twenty-two hydrogen atoms, andeleven oxygen atoms (C,2110).

MONITOR: An individual trained to meas-ure, record, and report radiation expo-sure and exposure rates; provide limitedfield guidance' on radiation hazards as-sociated with operations to which he isassigned; and perform operator's main-tenance of radiological instruments.

MONITORING: The procedure or opera-tion of locating and measuring radioac-tive contamination by means of surveyinstruments which can detect and meas-ure ionizing radiations. The individualperforming the operation is called amonitor.

MUTATION: A change in the characteris-tics of an organism produced by alteringthe usual hereditary pattern. Radiationcan cause mutations in all living things.

N

NEGATIVE PHASE: See Shock Wave.

19

NEUTRON: A neutral particle, i.e., withno electrical charge, of approximatelyunit mass, present in all atomic nuclei,except those of ordinary (light) hydro-gen. Neutrons are required to initiatethe fission process, and large numbersof neutrons are produced by both fissionand fusion reactions in nuclear explo-sions.

NUCLEAR FISSION: See Fission.

NUCLEAR RADIATION: Particulate andelectromagnetic radiation emitted fromatomic nuclei in various nuclear proc-esses. The important nuclear radiations,from the weapons standpoint, are alphaand beta particles, gamma rays, andneutrons. All nuclear radiations are ion-izing radiations, but the reverse is nottrue; X-rays, for example, are includedamong ionizing radiations, but they arenot nuclear radiations since they do notoriginate from atomic nuclei. See Ioniz-ing Radiation, X-Rays.

NUCLEAR REACTOR: An apparatus inwhich nuclear fission is sustained in aregulated sell -supporting chain reaction.

NUCLEAR WEAPON (OR BOMB): A gen-eral name given to any weapon in whichthe explosion results from the energyreleased by reactions involving atomicnuclei, either fission' or fusion or both.Thus, the A- (or atomic) bomb and theH- (or hydrogen) bomb are both nuclearweapons. It would be equally true to callthem atomic weapons, since it is theenergy of atomic nuclei that is involvedin each case. However, it has becomemore-or-less customary, although it isnot strictly accurate, to refer to weap-ons in which all the energy results fromfission as A-bombs or atomic bombs. Inorder to make a distinction, those weap-ons in which part, at least, of the energyresults from thermonuclear (fusion) re-actions among the isotopes of hydrogenhave been called H-bombs or hydrogenbombs.

NUCLEON: The common namestituent particle of a nucleusproton or neutron.

for a con-such as a

NUCLEUS (OR ATOMIC NUCLEUS): Thesmall, central, positively charged regionof an atom which carries essentially allthe mass. Except for the nucleus of ordi-nary (light) hydrogen, which is a singleproton, all atomic nuclei contain bothprotons and neutrons. The number ofprotons determines the total positivecharge, or atomic number; this is thesame for all the atomic nuclei of a givenchemical element. The total number ofneutrons and protons, called the massnumber, is closely related to the mass(or weight) of the atom. The nuclei ofisotopes of a given element contain thesame number of protons, but differentnumbers of neutrons. They thus havethe same atomic number, and so are thesame element, but they have differentmass numbers (and masses). The nu-clear properties, e.g., radioactivity, fis-sion, neutron capture, etc., of an isotopeof a given element are determined byboth the number of neutrons and thenumber of protons. See Atom, Element,Isotope, Neutron, Proton.

NUDET: Report of nuclear detonation.

0ORGAN: Organized group of tissue having

one or more definite functions to per-form in a living body.

OUTSIDE/INSIDE RATIO (0I): Themeasured ratio of the fallout gammaradiation exposure rate at some pointoutside a shelter to the exposure rate atsome point inside the shelter. For radiol-ogical defense purposes, the specific out-side point selected should have minimalprotection. (See Protection Factor.)

.OVERPRESSURE: The transient pres-sure, usually expressed in pounds persquare inch, exceeding the ambientpressure, manifested in the shock (orblast) wave from\an explosion. The vari-ation of the overpressure with time de-pends on the energy yield of the explo-sion, the distance from the point ofburst, and the medium in which theweapon is detonated. The peak overpres -.sure is the maximum value of the over-

196193

pressure at a given location and is gen-erally experienced at the instant theshock (or blast) wave reaches that loca-tion. See Shock Wave.

P

PAIR PRODUCTION: The processwhereby a gamma-ray (or X-ray) pho-ton, with energy in excess of 1.02 MeV.in passing near the nucleus of an atomis converted into a-positive electron anda negative electron. As a result, thephoton ceases to exist. See Photon.

PEAK OVERPRESSURE: The maximumoverpressure value at the blast front.

PERIODIC TABLE: A chart showing thearrangement of chemical elements inorder of increasing atomic number inaddition to grouping according to cer-tain chemical similarities.

PERSONNEL EXPOSURE MEASURE-ME-/`.1- The measured exposure re-ceived by shelter occupants and opera-tions personnel in the field.

PHOTOELECTRIC EFFECT: The processwhereby a gamma-ray (or X-ray) pho-ton, with energy somewhat greater thanthat of the binding energy of an electronin an atom, transfers all its energy tothe electron which is consequently re-moved from the atom. Since it has lostall its energy, the photon ceases to exist.See Photon.

PHOTON: A unit or "particle" of electrom-agnetic radiation, possessing a quantumof energy which is characteristic of theparticular radiation. If v is the fre-quency of the radiation in cycles persecond and X is the wave length in centi-meters, the energy quantum of the pho-ton in ergs is hv or hcX where h isPlanck's constant, 6.62 x 10" erg-sec-ond and c is the velocity of light(3.00 x 1010 centimeters per second). Forgamma rays, the photon energy is us-ually expressed in million electron volt(MeV) units, i.e., 1.24 x 10"X where X isin centimeters or 1.24 x 10-2/X if X is inAngstroms.

PIG: A container (usually lead) used to

194

transport and store radioactive mate-rials. The thick walls protect the personhandling the container from nuclear ra-diation.

PLUTONIUM: (Chemical symbol Pu.) Amanmade transuranium element,atomic number 94. When uranium 238 isbombarded with neutrons in an atomicreactor some of the uranium is con-verted by nuclear reactions into pluton-ium, a fissionable material.

POINT SOURCE: A point at which radio-activity is concentrated as opposed to anarea over which radioactive materialmight be spread. The DCPA TrainingSource Set sealed capsule is an exampleof a point source.

POSITRON: Positively charged electron.

POSITIVE PHASE: See Shock Wave.

PROTECTION FACTOR (PF): The ratio ofgamma radiation exposure at a Stand-ard Unprotected Location to exposureat a protected location, such as a falloutshelter. The Standard Unprotected Lo-cation is defined as a point 3 feet abovean infinite, smooth, ground plane unifor-mally covered with fallout. Protectionfactor is a calculated value suitable forplanning purposes as an indicator ofrelative protection. (See Outside/InsideRatio.)

PROTON: A particle of mass (approxi-mately) unity carrying a unit positivecharge; it is identical physically withthe nucleus of the ordinary (light) hy-drogen atom. All atomic nuclei containprotons.-See Nucleus.

(None)

, R

RAD: A unit of absorbed dose of radiation;it represents the absorption of 100 ergsof nuclear (or ionizing) radiation pergram of the absorbing material or tis-sue.

RADEF: Radiological Defense.

RADIOACTIVE CLOUD: An all-inclusiveterm for the mixture of hot gases,smoke, dust, and other particulate mat-ter from the weapon itself and from theenvironment, which is carried aloft inconjunction with the rising fireball pro-duced by the detonation of a nuclearweapon.

RADIOACTIVITY: The spontaneous dis-integration of unstable nuclei with theresulting emission of nuclear radiation.

RADIATION EXPOSURE RECORD: Thecard issued to individuals for recordingtheir personal radiation exposures.

RADIATION INJURY: The harmful ef-fects caused by ionizing radiation.

RADIOLOGICAL DEFENSE: The organ-ized effort, through warning, detection,and preventive and remedial measures,to minimize the effect of nuclear radia-tion on people and resources.

RBE (RELATIVE BIOLOGICAL EFFEC-TIVENESS): The ratio of the number ofrads of gamma radiation of a certainenergy which will produce a specifiedbiological effect to the number of rads ofanother radiation required to producethe same effect is the RBE of this latterradiation.

REM: A unit of biological dose of radia-tion; the name is derived from the initialletters of the term "roentgen equivalentman (or mammal)." See RAD.

REMEDIAL MOVEMENT: Movement ofpeople postattack to a less contami-nated area or a better protected loca-tion.

REP: A unit of absorbed dose of radiationnow being replaced by the rad; the namerep is derived from the initial letters ofthe term "roentgen equivalent physi-cal." Basically, the rep was intended toexpress the amount of energy absorbedper gram of soft tissue as a result ofexposure to 1 roentgen of gamma (or X-)raidation. This is estimated to be about97 ergs, although the :actual value de-pends on certain experimental datawhich are not precisely known. The rep

is thus defined, in general, as the dose ofany ionizing radiation which results inthe absorption of about 97 ergs of en-ergy per gram of soft tissue. For softtissue, the rep and the rad are essen-tially the same. See RAD, Roentgen:

RESIDUAL NUCLEAR RADIATION:Nuclear radiation, chiefly beta particlesand gamma rays, which persists forsome time following a nuclear (oratomic) explosion. The radiation is emit-ted mainly by the fission products andother bomb residues in the fallout, andto some extent by earth and water con-stituents, and other materials, in whichradioactivity has been induced by thecapture of neutrons. See Fallout, In-duced Radioactivity, Initial Nuclear Ra-diatio.

ROENTGEN (R): A unit of exposure togamma (or X-) radiation. It is definedprecisely as the quantity of gamma (orX-) radiation such that the associatedcorpuscular emission per 0.001293 gramof air produces, in air, ions carrying oneelectrostatic unit quantity of electricityof either sign. From the accepted value(34 electron volts) for the energy lost byan electron in producing a positive-neg-ative ion pair in air, it is estimated that1 roentgen of gamma (or X-) radiation,would result in the absorption of about87 ergs of energy per gram of air.

SHELTER: A habitable structure or spacestocked with essential provisions andused to protect its occupants from fal-lout radiation.

SHIELDING: Any material or obstructionwhich absorbs radiation and thus tendsto protect personnel or materials fromthe effects of a nuclear explosion. Amoderately \thick layer of any opaquematerial will provide satisfactory shield-ing from thermal radiation, but a con-siderable thickness of material of highdensity may be needed for nuclear ra-diation shielding.

SHOCK WAVE: A continuously propa-gated pressure pulse (or wave) in the

198195

surrounding medium which may be air,water, or earth, initiated by the expan-sion of the hot gases produced in anexplosion. A shock wave in air is gener-ally referred to as a blast wave, becauseit resembles and is accompanied bystrong, but transient, winds. The dura-tion of a shock (or blast) wave is distin-guished by two phases. First there is thepositive (or compression) phase duringwhich the pressure rises very sharply toa value that is higher than ambient andthen decreases rapidly to the ambientpressure. The positive phase for the dy-namic pressure is somewhat longer thanfor overpressure, due to the momentumof the moving air behind the shockfront. The duration of the positive phaseincreases and the maximum (peak) pres-sure decreases with increasing distancefrom an explosion of given energy yield.In the second phase, the negative (orsuction) phase, the pressure falls belowambient and then returns to the am-bient value. The duration of the nega-tive phase is approximately constantthroughout the blast wave history andmay be several times the duration of thepositive phase. Deviations from the am-bient pressure during the negativephase are never large and they decreasewith increasing distance from the explo-sion. See Dynamic Pressure, Overpres-sure.

SOMATIC: Of or relating to the body, asopposed to the spirit; physical.

SPECTRUM: An image, visible or invisi-ble, formed by rays of light or otherradiant energy, in which parts are ar-ranged according to their refrangibilityor wave-length, so that all of the samewave-length fall together while those ofdifferent wave-lengths are separatedfrom each other, forming a regular pro-gressive series.

STRATOSPHERE: A relatively stablelayer of the atmosphere between thetropopause and a height of about 30miles in which the temperature changesvery little (in polar and temperatezones) or increases (in the tropics) withincreasing altitudes. In the stratosphere

1 96

clouds of Water never form and there ispractically no convection. See Tropo-pause, Troposphere.

SUBCRITICAL: The inability`of a fission-able material to support a self-sustainedchain reaction.

SUBSURFACE BURST: See UndergroundBurst, Underwater Burst.

SUPERCRITICAL: A term used to' de-scribe the state of a given fission systemwhen the quantity of fissionable mate-rial is greater than the critical massunder the existing conditions. A highlysupercritical system is essential for theproduction of energy at a very rapidrate so that an explosion may occur. SeeCritical Mass.

SURFACE BURST: The explosion of a.nuclear (or atomic) weapon at the sur-face of the land or water or at a heightabove the surface less than the radius ofthe fireball at maximum luminosity (inthe second thermal pulse). An explosionin which the weapon is detonated ac-tually on the surface jor within 5W°3feet, where W is the explosion yield inkilotons, above or below the surface) iscalled a contact surface burst or a truesurface burst. See Air Burst.

SURVEY METER: A portable instrument,such as a Geiger counter or ionizationchamber, used to detect nuclear radia-tion and to measure the exposure rate.See Monitoring.

SYNDROME, RADIATION: The complexof symptoms characterizing the diseaseknown as radiation injury,resultingfrom excessive exposure of the whole (ora large part) of the body to ionizingradiation. The earliest of these symp-toms are nausea, vomiting, and diar-rhea, which may be followed by loss ofhair (epilation), heinmorhage, inflamma-tion of the mouth and throat, and gen-eral loss of energy. In severe cases,where the radiation exposure has beenrelatively large, death may occur withintwo to four weeks. Those who survive 6weeks after the receipt of a single expo-sure of radiation may generally be ex-pected to recover.

19

T

TAMPER: A strong container.

THERMAL ENERGY: The energy emit-ted from the fireball as thermal radia-tion. The total amount of thermal en-ergy received per unit area at a speci-fied distance from a nuclear (or atomic)explosion is generally expressed interms of calories per square centimeter.See Thermal Radiation.

THERMONUCLEAR: An adjective refer-ring to the process (or processes) inwhich very high temperatures are usedto bring about the fusion of light nuclei,such as those of the hydrogen isotopes(deuterium and tritium), with the ac-companying liberation of energy. Athermonuclear bomb is a weapon inwhich part of the explosion energy re-sults from thermonuclear fusion reartions. The high temperatures requiredare obtained by means of a fission explo-sion. See Fusion.

THERMAL RADIATION: Electromag-netic radiation emitted (in two pulsesfrom an air burst) from the fireball as aconsequence of its very high tempera-ture; it consists essentially of ultravi-olet, visible, and infrared radiations. Inthe early stages (first pulse of an airburst), when the temperature of thefireball is extremely high, the ultravi-olet radiation predominates; in the sec-ond pulse, the temperatures are lowerand most of the thermal radiation lies inthe visible and infrared regions of thespectrum. From a high-altitude burst,the thermal radiation is emitted in asingle short pulse.

TNT EQUIVALENT: A measure of theenergy released in the detonation of anuclear weapon, or in the explosion of agiven quantity of fissionable material,expressed in terms of the weight of TNTwhich would release the same amount ofenergy when exploded. The TNT equiva-lent is usually stated in kilotons or me-gatons. The basis of the TNT equiva-lence is that the explosion of 1 ton ofTNT releases 109 calories of energy. SeeKiloton, Megaton, Yield.

TRANSMUTATION: The changing of oneelement into another by a nuclear reac-tion.

TRITIUM: A radioactive isotope of hydro-gen, having a mass of 3 units; it isproduced in nuclear reactors by the ac-tion of neutrons on lithium nuclei.

TROPOPAUSE: The imaginary boundarylayer dividing the stratosphere from thelower part of the atmosphere, the tropo-sphere. The tropopause normally occursat an altiture of about 25,000 to 45,000feet in polar and temperate zones, andat 55,000 feet in the tropics.

TROPOSPHERE: The region of the atmos-phere immediately above the earth'ssurface and up to the tropopause inwhich the temperature falls fairly regu-larly with increasing altitude, cloudsform, convection is active, and mixing iscontinuous and more or less complete.

U

ULTRAVIOLET: Electromagnetic radia-tion of wave length between the short-est visible violet and soft X-rays.

UNDERGROUND BURST: The explosionof a nuclear weapon with its centermore than 5W°3 feet, where W is theexplosion yield in kilotons, beneath thesurface of the ground. See ContainedUnderground Burst.

UNDERWATER BURST: The explosion ofa nuclear weapon with its center be-neath the surface of the water.

URANIUM: (Chemical symbol U.) Theheaviest naturally occurring radioactiveelement, atomic number 92. The onlyappreciable source of fissionable mate-rial occurring in nature is in uraniumore. This contains about 0.7% of thefissionable isotope U235 and 99.3% of thenonfissionable isotope U238.

V

(None)

w

WEIGHT: A measure of the force withwhich matter is attracted to the earth.

197

20 )

WORLDWIDE FALLOUT: See Fallout.

X

X-RAYS: Electromagnetic radiations ofhigh energy having wave lengthsshorter than those in the ultravioletregion, i.e., less than 10-6 cm or 100Angstroms. As generally produced by X-ray 'machines, they are bremsstrahlungresulting from the interaction of elec-trons of 1 kilo-electron volt or more en-ergy with a metallic target. See GammaRays, Electromagnetic Radiation.

198

201

Y

YIELD (OR ENERGY YIELD): The totaleffective energy released in a nuclearexplosion. It is usually expressed interms of the equivalent tonnage of TNTrequired to produce the same energyrelease in an explosion. The total energyyield is manifested as nuclear radiation,thermal radiation, and shock (and blast)energy, the actual distribution being de-pendent upon the medium in which theexplosion occurs (primarily) and alsoupon the type of weapon and the timeafter detonation.

(None)

U S Government Prtnttng Once 1974 0- 551.401