University of Notre Dame

Department of Risk Management and Safety

2013 Radiation Safety Refresher Training

INTRODUCTION

• Lessons 1-5 will provide a review of some general knowledge of radiation with which all radioactive material and radiation producing machines should be familiar.

• Lessons 6-14 address specific safety practices and procedures applicable to laboratories at Notre Dame

Lesson 1Forms of Radiation

Forms of Ionizing RadiationIonizing radiation includes emissions with energies greater than 20 electron volts that cause ionizations when interacting with matter.Sources of ionizing radiation at Notre Dame include:

Particulate Radiation

− Alpha− Beta

Photon Radiation− Gamma− X-Ray

BETA RADIATION– Consists of an electron– Very small size moving at up to 99%

the speed of light– Hazard depends on decay energy of

isotope

• ALPHA RADIATION – Consists of two protons and

two neutrons (helium nucleus)– Massive size, moving at 80%

the speed of light– Internal Hazard

Particulate Radiation

Examples of Beta Emitters• H-3: Energy max = 19 Kev: Internal Hazard• C-14: Energy max = 160 Kev: Internal Hazard• S-35: Energy max = 170 Kev: Internal Hazard• P-32: Energy max = 1700 Kev: Internal and

external hazard

−The lower energy beta emitters are less penetrating and present less of a hazard. The concerns with these isotopes is primarily associated with internal exposure due to ingestion, inhalation, or skin absorption

−Higher energy beta emitters are more penetrating and present both internal and external hazards

Photon RadiationGAMMA RADIATION

– A wave radiation consisting of a photon

– Travels at the speed of light– Created in the nucleus of the

atom

X-RAYS – A wave radiation consisting of a

photon– Travels at the speed of light– Created in the electron shell of

the atom

Examples of Gamma Emitters

• I-125: Energy max = 35 Kev: Internal/External Hazard

• Cs-137: Energy max= 662 Kev: Internal/External Hazard

− Gamma Emitters have no mass and are very penetrating

− All gamma emitting isotopes and are considered both internal and external hazards

Bremsstrahlung Radiation− Literally: breaking radiation− Electromagnetic radiation produced

when an electrically charged particle is slowed down by the electric field of an atomic nucleus

− Example: The beta particle emitted by a P-32 atom will interact with lead to give off an x-ray

− Bremsstrahlung production must be considered when planning the shielding of high energy beta emitters

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Lesson 2Units of Radioactivity

Units of Radioactivity

The Curie (Ci) – Commonly used in the United States1 Ci = 3.7E10 disintegrations per second1 Ci = 2.2E12 disintegrations per minute1 Ci = 1000 millicurie (mCi) = 1,000,000 microcurie (uCi)

The Becquerel (Bq) - International Unit

1 Bq = 1 disintegration per second1 MBq = 1,000,000 disintegrations per second1 GBq = 1,000,000,000 disintegrations per second

1 Bq = 2.7E-8 mCi

RAD• The RAD is the unit commonly used in the United States for

Absorbed Dose (D)• It is determined by the Energy that is actually deposited in

matter• 1 Rad = 100 ergs of deposited energy per gram of absorber

Gray• International Unit for Absorbed Dose

1 Gray = 100 Rads

Units of Radioactivity

REM• The REM is the unit commonly used in the

United States for the Dose Equivalent• Determined by Multiplying the absorbed dose

(D) times a quality factor (Q)• Q equals 1 for beta, gamma and x-rays, 5-20 for neutrons, and 20 for alpha

Sievert• International Unit for absorbed dose

1 Sievert = 100 REM

Units of Radioactivity

• Most labs at Notre Dame will use only beta, gamma and/or x-ray emittersThe Quality factor for these forms of radiation is equal to 1

Therefore the Rad is equal to the RemIf your lab is one of the few using alpha, remember that the

QF is 20. Therefore, one Rad of alpha is equal to 20 Rem.• Exposure reports are documented in mREM

1 REM = 1,000 mREM

Units of Radioactivity

Lesson 3Half Life

Half Life• The half life of a materials is the time required for

1/2 of the radioactive atoms to decay

• The half life is a distinct value for each radioisotope

Half Life of Selected Radioisotopes

• Flourine-18: 109.8 minutes• Phosphorus-32: 14.3 days• Tritium: 12.3 years• Carbon-14: 5,730 years• Uranium: 4,500,000,000 years

Example of Half LifeYou receive a shipment of 250 µCi of P-32

– The half life of P-32 is 14.3 daysIf you do not use the P-32 until 14.3 days after receiving the

material, you will only have 125 µCi left– If you wait 28.6 days, you will only have 62.5 µCi left

It is important to consider the half life of the radioisotope when planning a study that includes the use of radioactive materials

Lesson 4Background Radiation

Background Radiation• Natural and man-made sources of radiation

everybody is exposed to in their daily lives

• Typically 20 to 30 mRem per month

How Might I Be Exposed?

Average Annual Exposure to the General Public

• Cosmic• Terrestrial• Radon• Medical

• Total

• 30 mRem• 40 mRem• 230 mRem• 90 mRem

• 390 mRem

Lesson 5Biological Effects & Risk

Biological Effects• Data is largely based on high exposures to

individuals within the first half of the 20th century

• Biological effects occur when exposure to radiation exceeds 50 rads over a short period of time

• All occupational exposures are limited by city, state, or federal regulations

Radiation Damage• Mechanical: Direct hit to the DNA by the

radiation - Damages cells by breaking the DNA bonds

• Chemical: Generates peroxides which can attack the DNA

Damage can be repaired for small amounts of exposure

Radiosensitivity• Muscle Radioresistant• Stomach Radiosensitive• Bone Marrow Radiosensitive• Human Gonads Very Radiosensitive

Radiation Effects

• Acute Effects: Nausea, Vomiting, Reddening of

Skin, Hair Loss, Blood Changes

• Latent Effects: Cataracts, Genetic effects, Cancer

Dose Required for Acute Effects

If an individual receives a dose in excess of 50 Rem (50,000 mRem) in a

short period of time, he/she will experience acute effects

Risk of CancerThe level of exposure is related to the risk of illnessWhile the risk for high levels of exposure is apparent, the risk for low levels is unclearIt is estimated that 1 rem TEDE of exposure increase likelihood of cancer by 1 in 1000The likelihood of cancer in ones life time is 1 in 3 from all other factors

Factors Affecting Risk• The amount of time over which the dose

was received • The type of radiation• The general health of the individual• The age of the individual• The area of the body exposed

Lesson 6Occupational Exposure

What are the Occupational Exposure Limits ?

• Whole Body• Extremities• Skin of Whole Body• Lens of Eye• Thyroid

• 5,000 mRem/year• 50,000 mRem/year• 50,000 mRem/year• 15,000 mRem/year• 15,000 mRem/year

Other Occupational Limits

• ALARA - As Low As Reasonably Achievable. This is our policy AND the NRC’s: Don’t expose yourself to radiation any more than absolutely necessary.

Exposure to the General Public

• Annual limit of 100 mRem to individuals

• This includes anybody in the laboratory who does not work for Notre Dame

• Examples: salesmen, vendors, family members, etc.

Prenatal Radiation Exposure

• In the embryo stage, cells are dividing very rapidly and are undifferentiated in their structure and are more sensitive to radiation exposure

• Especially sensitive during the first 2 to 3 months after conception

• This sensitivity increases the risk of cancer and retardation

Declaring Pregnancy

– Additional dose restrictions are available for the pregnant worker

– Receive a monthly dosimeter– Limited to 500 mRem during the term of the pregnancy– Also, limited to 50 mRem per month– DECLARATION IS STRICTLY OPTIONAL

Exposure to MinorsIndividuals under the age of 18

– Must not receive an exposure greater than 10% of occupational exposure for adults

– Wholebody Exposure Limit: 500 mRem– Minors will wear dosimeters in laboratories

licensed for radioactive material use– Minors should not work with radioactive

material

Lesson 7Minimizing Exposure

How Do I Protect Myself?

Reducing the dose from any source radiation exposure involves the use of three protective measures:

– TIME– DISTANCE– SHIELDING

Time

− The amount of exposure an individual accumulates is directly proportional to the time of exposure

− Keep handling time to a minimum

Distance− The relationship

between distance and exposure follows the inverse square law. The intensity of the radiation exposure decreases in proportion to the inverse of the distance squared

− Dose2 = Dose1 x (d1/d2)2

Shielding− To shield against beta

emissions, use plexiglass to decrease the production of bremsstrahlung radiation.

− If necessary, supplement with lead after the plexiglass

− To shield against gamma and x-rays, use lead, leaded glass or leaded plastic

Internal Exposure− Only a few commonly used

radionuclides at Notre Dame present an external exposure potential

− All radionuclides present a potential for internal exposure if taken into the body. Entry into the body can occur by inhalation, ingestion, or absorption through the skin

Minimizing Internal Exposure

• Wear personal protective equipment

• If required, use a fume hood

• No eating, drinking or applying cosmetics

• Clean up spills promptly

• Routinely monitor work area

• Secure radioactive material

Minimum Protective Equipment

• Laboratory coat

• Gloves

• Safety Glasses

• Dosimeters (for certain

nuclides and/or

machines)

Lesson 8Regulatory Requirements

Notre Dame’s License• Broadscope license issued by the Nuclear

Regulatory Commission

• Permits the use of radioactive material in research and development, as well as education.

• Must be renewed every 10 years

Radiation Safety Requirements

• Radiation Safety Officer

• Radiation Safety Committee

• Approved Responsible Investigators

• Radioisotope Users

Records to be Kept on FileIn the Laboratory - Receipt of material - Utilization of material (logs) - Waste disposal - Monthly Wipe tests -Training verification

The NRC Inspectors will look specifically for these completed documents in the lab Radiation Safety notebooks which should be stored in every radiation lab.

By Radiation Safety -Principal Investigator -Isotope limits -Receipt of material -Waste transferred -Lab inspections -Exposure reports

Records (Continued)If radioactivity is not used or stored during a month, a signed statement may be substituted for a wipe testExample of Signed Statement:

“There has been no radioactive material use or storage in lab ____ during the month of ____”.

Radiation Safety Inspections

• Inspections are conducted at least every other month

• Review isotope use records and wipe test records• Confirm appropriate postings and labels• Personal protective equipment and dosimetry• Shielding and survey instrument available• Contamination and radiation dose rate survey

Where Will Isotopes be Found?

• In labs labeled with “Caution Radioactive Material” signs at the entrance

• Usually stored in freezers, refrigerators, or fume hoods

• Waste stored in labeled containers

• Radioactive waste storage rooms

Postings and Labels• Entrance to laboratory• Refrigerator/freezer• Equipment/instruments• Radioactive waste containers• Laboratory benches• Fume hoods for use

Labeling Containers• All containers used for storing radioactive material

or radioactive waste must be stored in labeled

containers

• The label displays the radiation symbol with the

words “Caution Radioactive Material”

• The isotope, activity in uCi or mCi and the start

date should be included on label

Lesson 9Radiation Detection

Detecting Radiation and Contamination

• Personal dosimeters are used to detect the occupational exposure to employees from external sources of radiation

• A survey meter may be used to detect large quantities of high energy beta and gamma emitters on a surface

• For smaller quantities of contamination on surfaces and low energy beta emitters, use the wipe test method

Film Badge Required when there is a

possibility of receiving greater than 10% of exposure limit

Monitors for gamma, x-ray and high energy beta

Worn for 2 months These are individual specific

- Do not loan out Return promptly after

receiving a new one

Ring Dosimeter Monitors exposure to the

hands Used for high energy

beta, gamma and x-ray radiation

Worn when handling sources like those listed above or x-ray machines

Survey Instruments• Geiger Mueller (G-M) - Detects alpha, beta, and gamma

radiation- Best option for detecting beta contamination

• Sodium Iodide Detector - Gamma and x-ray only

Operational Check• Check calibration date• Confirm calibration

date within past year• Check batteries• Check response to

radioactive source to confirm that the meter is operational

Survey Instruments

Survey Instruments• Geiger-Mueller

Detector– Used for beta, gamma

and x-ray emitters– Best for P-32, S-35 and

C-14– Will detect I-125 and

Cr-51

Sodium-Iodine Detector– Detects gamma and x-

ray emitters– I-125 and Cr-51– Do not use to detect

beta emitters

Wipe Test Method• The Wipe Test Method is a

means of monitoring for small amounts of contamination

• It is the only method in the lab for detecting H-3

• Wipe test surveys should include both areas where contamination is expected to be found and areas where it is not expected

Wipe Test1. Choose equipment and surfaces to wipe

2. Use a filter paper or Q-tip to wipe approximately 100 cm2.

3. Place filter paper or Q-tip in scintillation vial and add scintillation fluid (use enough fluid to fill at least ½ of vial)

4. Place sample in scintillation counter

5. Set scintillation counter to detect radioisotopes used in laboratory

6. Include a standard or sample containing a known amount of radioactive material

7. Include a background or control sample

Determining Activity of WipesIf the scintillation counter only provides results in counts per minute (cpm) it will be necessary to convert those results to disintegrations per minute (dpm). This can be done by including a control sample with your wipes that contains the isotope of interest.

dpm = cpm / counting efficiency

Standard (cpm) / Standard (dpm) = Efficiency

1 uCi = 2.22 X 106 dpm

Decay of the standard’s activity must be considered.

Lesson 10Contamination Control

Contamination• Definition: Radioactive material in an

undesired location

• Undesired locations: Surfaces, skin, internal, airborne

• Types: Removable – Decontamination is possible

Fixed – Unable to decontaminate

Contamination Limits•<20 dpm/100cm2 a in restricted areas•<1,000 dpm/100cm2 b/g in restricted areas (radioisotope laboratories)

•>1,000 dpm/100cm2 b/g immediately clean up to below 1,000 dpm/100cm2

Frequently Contaminated Itemsin Laboratories

• Radioactive containers (stock, flasks, beakers)• Laboratory benches and sinks• Laboratory apparatus and equipment

(Centrifuge, Freezer, Waterbath) • Radioactive waste containers• Refrigerator door handles• Laboratory door handles• Gloves and laboratory coats

Contamination Control• Work in areas designated for radioactive material• Use absorbent pads• Wear appropriate protective clothing• Change gloves frequently• Perform a dry run of the procedure without

radioactive materials− It is recommend that you set up well-

defined, clearly labeled radioactive material work stations and restrict radioactive materials use to those areas

Spill Response• Notify people working in the laboratory• Control access to the affected area• Wear gloves, lab coat, and safety glasses• Clean spill from the outer perimeter inward• Avoid spattering and generating aerosols• After initial clean up, monitor for contamination• Repeat process if contamination remains• Call the RSO (1-5037) if you need help or if the

spill is greater than 100 µCi

Decontamination of Skin• If the radioactive material is a high energy beta,

gamma, or x-ray emitter, monitor with a survey meter and record reading

• Gently wash the affected area for 15 minutes with lukewarm water and a mild soap

• If you continue to find contamination, repeat washing and monitoring for up to 3 times

• Record final survey meter readings• Contact Radiation Safety at 1-5037

Lesson 11Obtaining Radioactive Materials

Ordering Radioactive Material

• Orders are placed electronically through Buy ND• All orders must be approved by the Radiation Safety

Office• When purchasing radioactive material from a vendor

provide the following:– The Radioisotope– Amount of material – Name and phone number of P.I.

• All packages must be addressed to Central Receiving/100 Mason Services

attn: Risk Management and Safety

Ordering− Typically, orders arrive the

following day− Ensure that somebody is

available to pick up the Package

− Wear lab coat and dosimeter to pick up package

− Sign receipt log prior to leaving Safety

Check Contents− Check box for contamination

using a Geiger counter or wipe test.

− Confirm that content of package is not contaminated.

− If it is contaminated contact Safety.

− Deface or remove any radiation labels on the box and discard as regular waste.

Receiving Radioactive Material

Receiving Radioactive Material− Checking package for contamination (Left)− Defacing labels (Right)

Lesson 12Radioactive Waste

Radioactive Waste Disposal• Minimize generation of waste• Identify and segregate dry solid waste - long lived (H-3 and C-14) - - short lived (P-32 and S-35)•Complete a waste form for pickup• Keep disposal records

Do Not Mix Waste Types

• Do not place scintillation vials into dry solid waste containers

• Do not place dry solid waste into liquid scintillation vial waste

• Do not place liquid waste container into dry solid waste containers

• DO NOT MIX LONG AND SHORT HALF-LIVED WASTE (Break point = 89 days)

Holding Radioactive Waste for Decay

• Provide appropriate shielding for the waste• Seal the container to prevent individuals from

adding to the waste• Label the waste container with the isotope,

amount of radioactive material, and date the container was sealed

• Hold for 10 half-lives. This will be done by RM&S.

Radioactive Waste Containers

• DO NOT dispose of radioactive waste in:

- medical waste

containers

- general waste

containers

• Use only approved radioactive waste containers supplied by Radiation Safety which contains a warning label “Caution Radioactive Material”

Scintillation Vials• Place in a separate container from the dry solid radioactive

waste• Separate scintillation vials containing long lived isotopes

(H-3 and C-14) from those containing shorter lived isotopes (P-32, I-125)

• Ensure the lids are secured tightly on the bottles• Do not overfill the container• Complete a Radioactive Waste Form

Contaminated Sharps• Syringes• Pasteur Pipettes• Scalpel• Needles

– Radioactive sharps must be segregated from other radioactive waste and placed in a radioactive materials labeled sharps container.

Collecting Liquid• Use a durable carboy from RM&S

• Attach a radiation warning label to the bottle

• Document the isotope, activity and date on the container

• Secure the lid on the container at all times

Lesson 13Clearing Equipment

Clearing EquipmentFor repair by Engineering or Vendor:•Ensure equipment is empty of all samples, containers, and radioactive material

•Conduct wipe test and present results to RSO

•Monitor with survey meter

•Decontaminate equipment if required

Lesson 14Review

When Working with Low Energy Beta Emitters

• Examples: H-3, C-14, S-35, P-33• Follow General Safety Requirements• Use a GM survey meter for large quantities of

C-14, S-35 and P-33• Isolate, label, and dispose of waste• Secure material in refrigerator/freezer

When Working with High Energy Beta Emitters (P-32)

• Use Plexiglas shielding for storage• Wear Luxel dosimeter and extremity dosimeters if

required• Handle material behind a Plexiglas shield• Regularly monitor work area and gloves for contamination• Use a GM detector or liquid scintillation counter

Working with Gamma or X-ray Emitters (I-125)• Store in leaded containers• Pre-experiment thyroid scan for work with large

quantities or volatile forms of I-125• Wear Luxel dosimeter and extremity dosimeters if

required

• Use leaded glass/Plexiglas shield• Regularly monitor surfaces gloves• Use NaI detector or liquid scintillation counter• Post experiment thyroid scan for work with large

quantities or volatile forms of I-125

Telephone Numbers

• Radiation Safety: 1-5037• Fax: 1-8794• Risk Management & Safety website:

www.riskmanagement.nd.edu• After hours, weekends, holidays: Call

ND Security 1-5555