NRRPT Dosimetry and Exposure Control 2 — Questions and Answers
Question 1: A radiation worker receives 150 mrem from external exposure and 50 mrem from internal deposition in a calendar quarter. What is the total effective dose equivalent for that quarter?
- 150 mrem
- 50 mrem
- 200 mrem (Correct answer)
- 100 mrem
Correct answer: 200 mrem
Total effective dose equivalent combines both external and internal contributions: 150 + 50 = 200 mrem.
Question 2: Which dosimeter type uses lithium fluoride (LiF) crystals to measure accumulated radiation dose?
- Film badge
- Thermoluminescent dosimeter (TLD) (Correct answer)
- Optically stimulated luminescence (OSL)
- Pocket ionization chamber
Correct answer: Thermoluminescent dosimeter (TLD)
TLDs use lithium fluoride crystals that store energy from radiation and release it as light when heated, proportional to dose received.
Question 3: Under NRC regulations, the annual occupational dose limit for the lens of the eye is:
- 5 rem
- 15 rem (Correct answer)
- 50 rem
- 25 rem
Correct answer: 15 rem
10 CFR 20.1201 sets the annual occupational dose limit for the lens of the eye at 15 rem (150 mSv).
Question 4: What principle requires radiation protection programs to keep doses as low as reasonably achievable, considering economic and social factors?
- ALARA (Correct answer)
- TEDE
- CEDE
- ICRP
Correct answer: ALARA
ALARA (As Low As Reasonably Achievable) is the radiation protection principle requiring dose minimization beyond just meeting regulatory limits.
Question 5: A direct-reading pocket dosimeter reads 0 mR at the start of a shift and 340 mR at the end. If the worker's legal dose limit is 1250 mR/quarter, what percentage of the quarterly limit was used?
- 13.6%
- 27.2% (Correct answer)
- 34.0%
- 68.0%
Correct answer: 27.2%
340 mR ÷ 1250 mR × 100 = 27.2% of the quarterly limit was used.
Question 6: Which of the following best describes the committed effective dose equivalent (CEDE)?
- Dose from external sources only over a 50-year period
- Dose from internal radionuclides integrated over 50 years following intake (Correct answer)
- Annual whole-body dose from all sources
- Deep dose equivalent from penetrating radiation
Correct answer: Dose from internal radionuclides integrated over 50 years following intake
CEDE is the effective dose equivalent resulting from radionuclides deposited in the body, integrated over the 50-year period following intake.
Question 7: When bioassay results indicate a worker may have exceeded 10% of the Annual Limit on Intake (ALI), what action is required under 10 CFR 20?
- No action needed unless 50% ALI is exceeded
- Investigate and assess the intake (Correct answer)
- Immediately remove the worker from all radiation areas
- Notify the NRC within 4 hours
Correct answer: Investigate and assess the intake
10 CFR 20.2104 requires licensees to assess intakes and resulting committed effective dose equivalent when intake is suspected to exceed 10% of the ALI.
NRRPT Dosimetry and Exposure Control 2
A radiation worker receives 150 mrem from external exposure and 50 mrem from internal deposition in a calendar quarter.
What is the total effective dose equivalent for that quarter?