Radiological Dispersion Devices and Nuclear Weapons

An OverviewVictor E. Anderson, C.H.P.

Radiologic Health Branch

California Department of Public Health

Use of Radioactive Materials for Terrorist Attack

• Few, if any deaths due to radiation.

• Possible deaths due to the explosion.

?

• Most likely impact will psychological.

• The most important impact will be economic.

Use of Radioactive Materials for Terrorist Attack

Radiation Dose Delivery

• External Dose– Source– Fragments– Fallout

• Internal Dose– Primarily inhalation pathway.

Radiological Dispersion Devices can vary in complexity and

design.

Plastic Explosive

Radiography Source

OR

High Level SourceMegaCuries or more

Shielding

Lid w/explosive bolts

Mechanism for introducing explosive charge and detonating

weapon

Cooling system for decay heat is required

Types of RDD

• Improvised

• Purpose Built

• Manufactured

Most Likely RDD

• Economy of force and physics

• Improvised

• Explosive

• Possibly incendiary

Potential Radionuclides.

• Primary– Co-60– Cs-137– Ir-192– Sr-90 (Y-90 in equilibrium)– Am-241

• Based on availability and manufactured quantities.

Other Radionuclides

• Pu (Generally Pu-239 or Pu-238)

• U-235

• Thorium– Heavy Metal issues - ~ 109 mCi/metric ton

• Radium– Issues with obtaining sufficient quantities.

As the Cloud Moves Down Wind

Radioactive material is deposited as fallout.

Radiation Issues

• Ionizing Radiation– Emission of energy– X & Gamma Radiation– Beta and Alpha

• Measured in rem and millirem– Rates:rem/hr; mrem/hr– 100 rem = 1 Sievert

Radiation Issues

• Dose = Dose Rate X Time– 120 mrem/hr X (½ hr) = 60 mrem

• Immediate damage does not occur until after 100 rem of dose.

• Annual radiation worker limit: 5 rem/yr• Public dose limit: 100 mrem/yr

– Long term effects have not been detected at these low levels.

Radioactive Contamination

• Contamination is the presence of radioactive material in a place where it is not wanted.

• Radiation Contamination

• Contamination does emit radiation.

• Major concern is inside people.

First Responder Issues

• TURN ON YOUR SURVEY METERS!

• Use ICS and SEMS

• Life saving takes precedence over radiation control issues.

• Do keep track of first responders radiation dose.

• Remember: dose rate X time = dose.

First Responder Issues

• Call for help.

• Use SEMS to ask for:

• Radiologic Health Branch Strike Teams

• Ca National Guard Civil Support Team

• DOE Radiological Assistance Program (RAP) Team.

Care for Contaminated & Injured

• Contamination levels on patients– Will not cause radiation injuries to care givers.– Will not cause care givers to become

“casualties.”– Are a hygiene issue.

• TAKE CARE OF MEDICAL ISSUES FIRST!!!

Care for Contaminated & Injured

• When the patient is stabilized– Survey – where is the contamination?– Remove clothing as needed.– Use gauze, sponges, small amounts of soap and

water, or “baby wipes” to clean the contaminated areas.

– Use sheets and blankets to contain any contamination that can not be cleaned in the field.

Care for Contaminated & Injured

• At the ER– Do use a special area to survey and receive the

patient.– At the same time do the usual medical

screening.– Take care of the patient’s medical problems.– Decontaminate last.– Don’t lose track of patient’s condition.

Controlling ContaminationAt the ER

IN OUT

PATIENT

Downwind Issues

• Assessment

• When to evacuate?

• Mass decontamination and screening

• Recovery

Assessment

• Use computer models and measurements.

• Project where contamination is and levels.

• Determine projected dose rates

• Rapid

• Recommendation to Incident Command and Emergency Operations Center

When to evacuate?

• Use EPA Protective Action Guides (PAG).– Based on dose from deposition.– Greater than one rem in 24 hours.– Greater than two rem in one year.

• Use State Dose Assessment Center. If not available use:– Radiologic Health Branch Teams– Radiation Assistance Team (RAP)

Mass Decontamination and Screening

• Radioactive contamination is easily removed – soap and water, waterless cleaners, etc.

• Radiation dose to contaminated individuals is small.

• Major issue is decompression of individual and collective fears and concerns.

Mass Decontamination and Screening

• A plan is necessary.

• Gives the population direction and hope.

• Prevents mass exodus to hospitals.

• Must plan for large numbers ~ one million persons.

• Reception centers.

Mass Decontamination and Screening

• Giving everyone a shower is not the answer!~ 10% of the population is medically

challenged.

• Not all will be contaminated.Worried well problem.

• Some will only be partially contaminated.

Reception Centers

• Enough survey meters.• Supplies.

– Decontamination– Clothing

• Concentrate on minimum use of water.• Documentation• Volunteer Nuclear Medicine Doctors and

Radiation Oncologists

Public Communication

Clear

Multiple Languages

Provide Good Information

Public Communication

• Can help to prevent panic.• Key to keeping uninjured from going to

hospitals.• Must be followed up by educational

materials.– What is radiation?– What is the danger?– What can I do?

Law Enforcement Issues

• Evidence Collection and support.

• Security for first responders with respect to issues such as secondary devices.

• Security of the site to assure that unauthorized personnel do not enter.

• Crowd control and assistance for evacuees.

• Traffic Control

Surveillance Issues

• Determine contamination levels.• Plume projections help.• Need teams to survey ground.• Sample for loose and fixed contamination.

– Loose contamination is radioactive material that is easily transferred from one surface to another.

– Fixed contamination does not move easily.

• Suitable air, water, and other environmental testing.

Laboratory Issues

• Identification of the radioactive materials– Will occur almost immediately.– Field methods are sufficient.

• Laboratories will be needed to:• Analyze large numbers of samples for

radioactive materials content.– Air Plants– Water Meats Dairy Products

Laboratory Issues

• Does not require environmental sampling sensitivities – e.g., picocuries or less.

• High throughput

• Shorter count times.

• Good documentation.

• Sample dose rate limits should be based on equipment limits.

Laboratory Issues

• Laboratory personnel should be able to easily stay within radiation dose worker limits.

• Contamination control will be an issue.

• Storage and documentation of samples.– Radioactive– Non-radioactive

Some Thoughts

• How big – kilotons

• What will it do?

• How far?

• How many?

Nuclear Weapon Basics

• What is an explosion?– A very fast fire that has no place to go.

• Chemical Explosion– Powered by chemical changes

• Nuclear Explosion– Powered by nuclear changes

• Fission• Fusion

Fission Process

• Fissionable Materials – U-233, U-235, Pu-239.

• Atom is split by a neutron and you get:– Two or more smaller atoms– Two to three neutrons.

• Other atoms may or not be split.

Criticality

• Sub Critical– Does not sustain fission

• Critical– Neutron Population Steady– Cannot extract power

• Supercritical– Neutron population growing slowly– Can extract useful power.

Prompt Critical

• Neutrons are increasing very fast.

• Nuclear reaction is running away

• Result: A very, very fast burning nuclear fire.

• If confined, so that the explosive forces build up, then an explosion occurs.

Types of Fission Bombs

• Gun type

Types of Fission Bombs

• Implosion Type

Subcritical Core

High Explosive

Construction Issues

• Gun type is easiest to make.– Less efficient– Larger and heavier

• Implosion type is much harder– More efficient– Lighter and smaller

Type of Weapon Used

• Stolen– “Suitcase” bombs ~ 0.1 to 10 kt– Tactical Warheads ~ 1 to 20 kt.

• Improvised– Gun type– ~10 to 20 kt Range

National Planning Scenario

• Ten kiloton Weapon

• Major urban area– Business Centers– Ports– Malls

• California CDPH Scenario– Ground Burst

Effects Part One

• Intense nuclear reaction lasting for a tens to hundreds of microseconds.

• Fireball formation• Light in the form of visible light, heat, and high

energy photons (x and gamma rays).• Neutron Radiation• Electro-magnetic Pulse (EMP)• Shock or concussion wave.• Radioactive materials leading to fallout.

The Fireball

• Temperature starts at millions of degrees centigrade and falls to about 3,000 degrees centigrade at the maximum radius.

• Size varies with strength.R ≈ 145 (kt)0.4 for contact surface.R ≈ 110 (kt)0.4 for air burst.R ≈ 90 (kt)0.4 for surface burst.

Fireball Radius for 10 kt Surface Contact Burst

10 kt Distance to Ignite Structures(50 cal/cm2)

10 kt Approximate Distance For Third Degree Burns (~ 8 cal/cm2)

Immediate Ionizing Radiation Effects

• Large burst of X, Gamma, and Neutron radiation is given off during the explosion.

• For a dose of 1,000 rad, essentially 100% fatalities.

• For a dose of 500 rad, approximately 50% fatalities without medical care.

• “Natural” shields such as hills, concrete structures, etc. can provide some protection.

10 kt 1,000 Rad Immediate Dose

500 Rad Immediate Dose

Shock Wave

• The explosion will create a “wall” of compressed air that expands outward.

• This creates the blast or concessive effects.

• Damage is highly dependent on height of burst.

• Air or Ground

Shock Wave

• Ground Burst

• Wave moves up and along the ground.– Broken up by terrain features.– Hills– Valleys– Buildings

• Less efficient in causing damage.

Shock Wave

• Difficult to predict Destructive Effects

• Rough Guides– Generally an over pressure of ~ 5 - 10 psi will

severely damage most structures.– 10 kt airburst should severely damage all

structures out to about ½ mile from the explosion’s center (ground zero).

Shock Wave Damage

• Fragments

• Secondary fires

• Explosions from gas tanks

• Damage to vehicles and aircraft.

Potential Shock Wave Damage 10 Kt

Severe Building Damage

Shattered Glass Injuries

Fallout

• Probably the most dangerous effect from a nuclear weapon.

• The amount depends on size and type of burst.

• Ground burst yields the largest amount.• Air burst yields the lowest.• Weapon can be surrounded with Cobalt or

other materials to enhance fallout.

Fallout

• Spread and extent is highly dependent on weather conditions.

• Individuals may be killed from radiation exposure.

• Best defense is to leave or get into a shielded shelter (fallout shelter).

• Arrival time depends on wind speed.

Fallout

• Composed of fission fragments, activation products, and unused nuclear fuel.

• Initially decays off very rapidly.

• A(t) = activity after a period of time (t)

• Ao = equal activity at start.

2.1)( tAtA o

Fallout

• Dose rate follows previous activity decay law.

• After about six months, then fallout decays based on the longer lived materials.

• An initial dose rate of 1,000 rad/hr will fall to about 2 rad/hr in a week.

10 kt Idealized Fallout Dose Rates and Times

(15 MPH Wind Blowing from the South to the North)

1,000 R./hr

Arrival Time ~ 20 min minutes

500 R/hr

Arrival Time ~ 35 min

Fallout Issues

• Get population out of the area fast.• Radiation burns from heavy fallout can

occur.• Recommended that individuals in the areas

of greater than 10 rad per hour take a shower.

• Field decontamination will be complicated by injuries and ill population.

Response Issues

• Major event

• Initial confusion and chaos

• Set up EOC and Command Posts up wind.

• Define work areas

• Safe area< 2 mrem/hrNo special radiation precautions

Work Areas• Emergency Zone

– Area where workers can maintain doses less than or equal to 5 rem per year. (State radiation worker limits).

– Contamination control may require level A or equivalent PPE.

– Search and Rescue will be difficult.

• Life Saving Zone– Entry only to save lives.– Doses must be less than 100 rem per entry.

• Lethal Zone– No Entry– Dose Rates are too high.

Work Zones

• Zones will shrink as fallout decays.

• Controlling rescue worker’s dose is a must.

• Survivors who have greater than 1,000 rad are dead.

• Organization will be the key to survival.

Casualties

• CDPH Studies for a 10 kt Ground Burst Indicate– Approximately 60,000 individuals killed outright.

– An additional 60,000 individuals at risk from radiation syndrome death due to fallout.

• Death due to fallout radiation will be prolonged ranging from days to weeks.

• An extreme challenge to the local, state, and national medical care system.

Fallout Injuries

• Unknown

• Subject to factors of evacuation and time in area.

• For a ground burst, clearly higher.

• Will require decontamination.

• Beta burns.

• Possible whole body irradiation.

Refugee Issues

• Plan for large numbers.

• Consider how to screen rapidly.– For contamination.– For injuries.– For needs.

• Places to go.

• System must be humane.

Radioactive Screening

• Hand held instruments.– Inexpensive.– Labor intensive.

• Portal Monitors– Expensive.– Less labor.– Quick.

Concluding Remarks

• The planning problem involves many different disciplines.

• Because radiation issues will affect virtually everything, the Health Physicist ends up as a technical advisor, facilitator, and catalyst .

Hiroshima Today. Ground Zero is near the Center of the Picture

Concluding Remarks• With correct planning and training a good

response can happen.

• Clear objectives, good equipment, and a well led and organized response organization can prevail.