NRRPT Radioactive Material Control 5 — Questions and Answers
Question 1: A respirator with an assigned protection factor (APF) of 10 means it reduces the worker's airborne radioactive material intake by:
- 10% relative to no protection
- To one-tenth of the ambient airborne concentration (Correct answer)
- By 10 rem of committed effective dose
- To a level 10 times above the derived air concentration
Correct answer: To one-tenth of the ambient airborne concentration
An APF of 10 means the respirator allows no more than 1/10 of the ambient concentration to reach the wearer's breathing zone.
Question 2: Which regulatory standard governs the packaging and transport of radioactive material by all modes of transport in the United States?
- 10 CFR Part 20 — Standards for Protection Against Radiation
- 49 CFR Parts 171–180 — DOT Hazardous Materials Regulations (Correct answer)
- 10 CFR Part 71 — Packaging and Transportation of Radioactive Material
- 40 CFR Part 190 — EPA Environmental Radiation Standards
Correct answer: 49 CFR Parts 171–180 — DOT Hazardous Materials Regulations
The Department of Transportation's hazardous materials regulations in 49 CFR govern all modes of transport for radioactive material within the US.
Question 3: Radioactive material with a half-life of 30 days is stored for 90 days. What fraction of the original activity remains?
- 1/8 (Correct answer)
- 1/4
- 1/6
- 1/3
Correct answer: 1/8
After 3 half-lives (90/30 = 3), the remaining fraction is (1/2)³ = 1/8 of the original activity.
Question 4: Which of the following is the MOST reliable method to confirm that an area is free of residual radioactive contamination after decontamination?
- Visual inspection for discoloration or staining
- Systematic smear surveys analyzed by liquid scintillation or proportional counting (Correct answer)
- Ambient dose rate survey with an ionization chamber
- Worker self-declaration after completing decontamination
Correct answer: Systematic smear surveys analyzed by liquid scintillation or proportional counting
Smear surveys collected in a systematic grid pattern and counted in a laboratory provide quantitative removable contamination data well below field instrument detection limits.
Question 5: A facility generates aqueous radioactive waste with 0.001 µCi/mL of H-3. Before releasing it to the sanitary sewer under 10 CFR 20.2003, what must be verified?
- The concentration does not exceed the annual average limit and total annual discharge limits are met (Correct answer)
- A separate NRC amendment is obtained for each discharge event
- The liquid is first solidified and then redissolved below detection limits
- Local sewer authority approval is the only required authorization
Correct answer: The concentration does not exceed the annual average limit and total annual discharge limits are met
10 CFR 20.2003 requires that sanitary sewer releases not exceed the concentration limit (averaged over a month) and that total annual release quantities stay within prescribed limits.
Question 6: During a personnel contamination event, a worker has detectable skin contamination that cannot be removed after three gentle washing attempts. The next appropriate action is to:
- Use abrasive scrubbing compounds to remove the remaining activity
- Notify the RSO and seek medical evaluation for possible skin dose assessment (Correct answer)
- Apply a waterproof bandage over the area and continue work
- Perform a whole-body bioassay to determine internal dose
Correct answer: Notify the RSO and seek medical evaluation for possible skin dose assessment
Persistent skin contamination requires RSO involvement and medical evaluation to assess skin dose and determine whether further decontamination is safe or medically warranted.
Question 7: The ALARA principle as applied to radioactive material control requires that exposures be reduced:
- Below the 5 rem/year occupational limit by any means available regardless of cost
- To levels as low as reasonably achievable considering economic and social factors (Correct answer)
- To zero activity whenever technically possible
- To natural background levels before material can be released
Correct answer: To levels as low as reasonably achievable considering economic and social factors
ALARA mandates optimization: dose reductions are pursued as long as the benefit of further reduction is proportionate to the effort and cost required.
NRRPT Radioactive Material Control 5
A respirator with an assigned protection factor (APF) of 10 means it reduces the worker's airborne radioactive material intake by: