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2. Sealed Source Safety Retraining Updated 09/2012
Radiological & Environmental Management
Purdue University

3. Training Goals Basic Radiation Safety Principles
Familiarization with Regulations
Purdue’s Policies and Procedures

4. What is radioactivity? Radioactivity is an energy
This energy is produced when an unstable nucleus spontaneously emits particles and/or electromagnetic radiation
Radioactive material sources
Sources are characterized as either sealed or unsealed (or “open”)
To qualify as a “sealed” source, the source must pass a battery of stress tests and be certified under NRC regulations

5. Definition Sealed Source
Means any byproduct material that is encased in a capsule designed to prevent leakage or escape of the byproduct material (USNRC Regulations 10CFR30.4)

6. Pictures of common sealed sources

7. Ionizing Radiation Types
Alpha
Molecularly large particle (2 protons and 2 neutrons), give up their energy in a short distance (approximately 1 ½ inches in air)
Beta
Smaller particle (electron), distance traveled ranges from several inches to a few feet (depending on its energy)
Gamma
Non-particulate energy wave, can travel several feet and easily penetrates material with low atomic mass
Neutron
Neutral particle, can travel greater distances than gamma radiation and easily penetrate material with low hydrogen ion concentrations

8. Risks of Radiation Exposure
An average person in the United States receives annual radiation dose of ~620 mrem, which includes exposure received from cosmic and natural radiation, medical treatment, and consumer products.
Large doses of radiation have been known to increase risk of cancer, birth defects, and possibly genetic effects.
Low doses seem to show no statistical differences in biological risk; however, some people believe there is risk at all levels above background exposure.
At radiation levels around 1 rem, it has been estimated that the increased incidence of cancer is 0.03% - the normal incidence of cancer for the average person is 25%.
Risk of developing genetic effects is half the risk of cancer.

9. 4 Factors to Reduce Exposure
Contamination Control
gloves, lab coats, fume hoods, absorbent paper
Time
do dry run, practice procedure to minimize time
Distance
a little distance between you and a source can significantly decrease your exposure from it (follows the “Inverse-Square Law”)
Shielding
Use proper shielding between you and a source to decrease personal exposure
betas - wood, Plexiglas (do NOT use lead)
gammas - lead, leaded glass

10. Click here for a sample calculation
Inverse Square Law
Point Sources
The intensity of radiation decreases as the inverse square of the distance.
Doubling distance, exposure = ¼ of original; Tripling distance, exposure = 1/9 of original. 2 1
I1d
= I2 d
Click here for a sample calculation

11. Sample Calculation I1 = 20 mR/hr I2 = ?? d1 = 1 ft d2 = 2 ft
(I1)(d1)2 = (I2)( d2)2
(20 mR/hr)(1ft)2 = (I2)(2ft)2
(20 mR/hr)(1ft)2 = I2
(2ft)2
(20 mR/hr)(1ft2) = I2
(4ft2)
I2 = 5 mR/hr
I1 = 20 mR/hr I2 = ?? d1 = 1 ft d2 = 2 ft

12. Inverse Square Law - Diagram

13. Ionizing Radiation Shielding
Different shields are needed to minimize external exposure

14. Rules Governing Use of Radionuclides
Radioactive material use must be licensed by the United States Nuclear Regulatory Commission (USNRC) or state agency. In Indiana, the USNRC is the regulating body.
Radiation Safety Officer (RSO) develops and maintains a Radiation Safety Manual, which must be followed by individuals working under the NRC license, and it is enforceable by law
Purdue University’s Radiation Safety Committee (RSC) also oversees and governs the radiation safety program.

15. Regulations
10CFR19
Rights and responsibilities of radioactive material licensees are outlined.
10CFR20
Standards for protection against radiation: this discusses issues such as procedures and regulatory limits
Declared pregnant worker
Security of radioactive materials

16. 10CFR Part 19 Instruction to workers
Rights
to be informed of storage, transfer, and use of radioactive materials
to further instruction on health protection problems associated with radiation exposure and procedures to minimize exposure
to receive radiation exposure history
to request an NRC inspection
to be instructed in and required to observe applicable provisions of NRC regulations and licenses
to be instructed in the appropriate response to warnings

17. NRC Policy Statement
Retaliation against employees or students engaged in protected activities, whether they have raised safety concerns within the University or to the NRC, will not be tolerated
Problems should be addressed within the existing University hierarchy – contact the radiation safety office if you have any concerns regarding issues involving radioactive materials.

18. 10CFR20 Occupational dose limits Surveys and monitoring
Precautionary procedures
Waste disposal
Records of surveys
Enforcement
Storage and control of licensed material

19. 10CFR20 Occupational Dose Limits
Target
Dose Limit
Whole Body
5 rem/yr
Organ or Tissue
50 rem/yr
Skin or Extremities
Lens of Eye
15 rem/yr
Minor (i.e. non-adult)
10% of adult limits
Declared Pregnant Worker
0.5 rem per 9-month gestation period
All dose limits include exposure from both internal and external sources.

20. Regulatory Guide 8.13 Prenatal Exposure
If a worker wishes to declare her pregnancy, she must declare it in writing to the Radiation Safety Officer.
A declaration of pregnancy is entirely voluntary, and can be withdrawn at any time – no reason needs to be given.
For a worker wishing to declare her pregnancy, she should contact REM for Declared Pregnant Worker Training, which covers important information, and provides her the declaration form she needs in order to declare her pregnancy. REM will also provide a fetal dosimeter at the time of declaration, assuming that it is warranted by the type of radiation that has the potential for exposure to the worker.
The dose limits will be reduced from 5 rem per year to the worker, to 0.5 rem to the fetus for the 9-month gestation period (this is for both external and internal exposure)

21. Radiation Units Exposure= ability of photons to ionize air
Roentgen (milliroentgen, mR)
Geiger-Mueller readings
Absorbed Dose= energy deposited in matter
Rad (millirad, mrad)
Dose Equivalent= biological weighted absorbed dose (tissue)
rem (millirem, mrem)
these units are what film badge (dosimetry) results are reported

22. Acute Effects of Radiation Exposure
Non-stochastic:
Until a minimum exposure level is reached, there is no biological effect.
Once that minimum exposure level is exceeded, the biological effect grows proportionally with the exposure.
The Lethal Dose to 50% of the population (LD50) is about 600 rad
Examples of biological response (effects) from radiation
erythema (skin reddening)
blood changes (marrow depression is seen at approximately 200 rad)
Gastrointestinal Syndrome (severe vomiting, diarrhea) – happens at approximately 1000 rad, and death is a likely outcome.

23. Delayed Effects of Radiation Exposure
Stochastic (occur by chance, statistical basis)
No threshold, but as the dose increases, the probability of the effect also increases
Examples of stochastic effects: may be seen 5 to 20 years after the exposure
Cancer
Leukemia
Cataracts
Life Shortening
Data extrapolated from high dose data (early radiology, Hiroshima/Nagasaki bombing, Chernobyl nuclear plant fire)

24. Risk Analysis
High doses - there is a correlation between dose and effect
Low doses (<10 rem) - it is unclear what the risk is at this level
difficulty performing long-term studies on effected people, while eliminating other factors (e.g. did the radiation worker get cancer from her work, or that she smoked cigarettes, or that she was genetically programmed that way)
Hormesis – this is a theory that low doses of radiation may actually be beneficial

25. Surveys
You can use Geiger-Mueller Survey instrument for detection of higher-energy beta and gamma sources.
REM will be conducting “leak tests” on sealed sources to evaluate whether the source containment is intact
this will be done at timely intervals.
Survey work areas, floors around work areas and any doors, lab coat, hands, shoes, if it is felt that the source integrity has been compromised (e.g. dropped, smashed, had acid spilled on it)
Record survey results, maintain records for 3 years

26. Security NRC Area of Emphasis
Secure laboratories when unoccupied (if this is not feasible, secure the radioactive material)
Challenge visitors or unauthorized individuals
REM accounts for RAM through inventory records
Assume only you are approved for the type of materials you are using. If another group wants to borrow them, you must ALWAYS check with the radiation safety office before relinquishing control of the material.

27. Emergency Procedures Call 911 Assist personnel if injured
Monitor personnel if contamination is suspected
Control area - inform other personnel of the situation and advise them not to enter
Notify radiation safety office, once emergency personnel are en route

28. Severe Personal Injury
Medical needs come first! Postpone monitoring, call 911, notify of radioactive material use
Wait for medical personnel - calmly advise radioactive materials may be involved
Trained radiation worker may need to accompany patient to treatment center.
Notify REM

29. Review Always use ALARA No eating, drinking, or smoking in labs
Always secure materials, lock doors
Never allow unauthorized users access to radioactive materials
Call REM for any related questions ( )
All Emergencies – call 911

30. REM’s Radiation Safety Group
James F. Schweitzer, Ph.D
Radiation Safety Officer
Zachariah C. Tribbett
Health Physicist
Sharon K. Rudolph
Isotope Ordering & Distribution
Jerry J. Gibbs
Waste Handling & Meter Calibration
Mike Nicholson
Waste Handling & Animal Hospital Support
REM Main Office
Civil Engineering Building, Room B
Section 1

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