Radiation Health and Safety Test Radiation Health and Safety Test Radiation Protection & Shielding 2 — Questions and Answers
Question 1: What is the recommended annual radiation dose limit for members of the general public from licensed operations?
- 50 mSv (5 rem)
- 20 mSv (2 rem)
- 5 mSv (500 mrem)
- 1 mSv (100 mrem) (Correct answer)
Correct answer: 1 mSv (100 mrem)
The NRC limits public exposure from licensed nuclear operations to 1 mSv (100 mrem) per year, reflecting the stricter standard applied to non-occupationally exposed individuals.
Question 2: Which device is used to detect and measure radiation in an area to ensure safe working conditions?
- Sphygmomanometer
- Geiger-Müller counter (Correct answer)
- Spirometer
- Thermoluminescent chip
Correct answer: Geiger-Müller counter
A Geiger-Müller (GM) counter detects ionizing radiation by measuring the ionization current in a gas-filled tube and is widely used for area surveys.
Question 3: What is the primary radiation hazard associated with radioiodine (I-131) used in nuclear medicine?
- External gamma exposure only
- Skin burns from beta particles
- Internal contamination via inhalation or ingestion concentrating in the thyroid (Correct answer)
- Neutron activation of nearby materials
Correct answer: Internal contamination via inhalation or ingestion concentrating in the thyroid
I-131 is both a beta and gamma emitter; its primary hazard is internal contamination, as the thyroid selectively accumulates iodine, leading to high local radiation doses.
Question 4: What is the half-value layer (HVL) in radiation shielding?
- The depth at which all radiation is absorbed
- The thickness of material that reduces radiation intensity by 50% (Correct answer)
- The radiation dose at the surface of a shield
- The decay time for a radioactive source to lose half its activity
Correct answer: The thickness of material that reduces radiation intensity by 50%
The HVL is the thickness of a specified material required to attenuate the intensity of a radiation beam to one-half of its original value.
Question 5: For pregnant radiation workers, what is the NRC recommended equivalent dose limit to the embryo/fetus during the entire gestational period?
- 50 mSv (5 rem)
- 5 mSv (500 mrem) (Correct answer)
- 20 mSv (2 rem)
- 0.5 mSv (50 mrem)
Correct answer: 5 mSv (500 mrem)
The NRC limits fetal dose to 5 mSv (500 mrem) over the entire gestation period once pregnancy is declared, with an additional monthly limit of 0.5 mSv.
Question 6: What radiation protection principle requires justifying any practice that increases radiation exposure by demonstrating its benefit outweighs the risk?
- Optimization
- Justification (Correct answer)
- Dose limitation
- ALARA
Correct answer: Justification
The ICRP's principle of justification requires that any use of radiation must produce sufficient benefit to offset the radiation detriment it causes.
Radiation Health and Safety Test Radiation Health and Safety Test Radiation Protection & Shielding 2
What is the recommended annual radiation dose limit for members of the general public from licensed operations?