NRRPT Decontamination & Exposure Prevention 5 — Questions and Answers
Question 1: A Contamination Area posting requires surveys to be performed at what minimum frequency under typical NRC-licensed facility procedures?
- Once per year during annual audits
- At the frequency specified in the facility's radiation protection program, often daily or before each entry (Correct answer)
- Only when visible contamination is suspected
- Weekly unless dose rates are elevated above 100 mrem/hr
Correct answer: At the frequency specified in the facility's radiation protection program, often daily or before each entry
Survey frequency is dictated by the facility's RP program and radiological conditions; contamination areas typically require surveys before entry or daily at minimum.
Question 2: Which of the following best describes the 'doffing' sequence for protective clothing to minimize self-contamination?
- Remove coveralls first, then booties, then outer gloves, then hood
- Remove outer gloves first, then hood, then booties, then coveralls, rolling outward as removed (Correct answer)
- Remove hood first to allow full visibility, then gloves, then coveralls
- The sequence does not matter as long as all items are removed before the frisker check
Correct answer: Remove outer gloves first, then hood, then booties, then coveralls, rolling outward as removed
Proper doffing removes outer gloves first to enable clean handling of other items, then proceeds systematically rolling contaminated surfaces inward to prevent spread.
Question 3: What is the significance of a radionuclide's 'effective half-life' in internal contamination assessment?
- It determines how quickly shielding can be reduced around a contaminated worker
- It combines physical decay and biological elimination to predict how long the body retains significant activity (Correct answer)
- It equals the physical half-life divided by two for dose calculation purposes
- It applies only to noble gas radionuclides with no biological retention
Correct answer: It combines physical decay and biological elimination to predict how long the body retains significant activity
Effective half-life accounts for both physical radioactive decay and biological clearance, determining how long internally deposited activity delivers dose to the body.
Question 4: HEPA filters used in respiratory protection and ventilation systems are rated to capture particles at what minimum efficiency?
- 85% of particles 0.3 micrometers and larger
- 99.97% of particles 0.3 micrometers and larger (Correct answer)
- 95% of all airborne particles regardless of size
- 99% of particles 1.0 micrometer and larger
Correct answer: 99.97% of particles 0.3 micrometers and larger
HEPA filters must capture at least 99.97% of airborne particles at 0.3 micrometers (the most penetrating particle size), ensuring highly effective removal of radioactive aerosols.
Question 5: A worker receives a positive nasal smear result after working in a potentially airborne contamination environment. This finding primarily indicates:
- External contamination of the face that does not imply internal exposure
- Possible inhalation of radioactive material, warranting bioassay to assess internal dose (Correct answer)
- That the worker's respirator was functioning correctly and filtered the contamination
- Only surface contamination of the nasal passage with no lung involvement
Correct answer: Possible inhalation of radioactive material, warranting bioassay to assess internal dose
A positive nasal smear indicates potential inhalation and requires bioassay (whole-body count or urinalysis) to determine if material reached the lungs and to estimate committed dose.
Question 6: When establishing a 'buffer zone' (also called a contamination reduction zone) around a radiological work area, its primary function is to:
- Provide shielding from direct radiation exposure to the public
- Serve as a transition area where workers can remove and check protective clothing before entering the clean area (Correct answer)
- House dosimetry storage and radiological instruments for the job
- Satisfy NRC posting requirements for High Radiation Areas
Correct answer: Serve as a transition area where workers can remove and check protective clothing before entering the clean area
The buffer zone is a transition space where workers doff anti-C clothing, perform frisker checks, and prevent contamination from being tracked into unrestricted areas.
Question 7: Which of the following engineering controls is MOST effective at preventing airborne contamination during radiological decontamination work?
- Requiring workers to hold their breath while near the source
- Using local exhaust ventilation (LEV) or a glove box to capture contaminants at the source (Correct answer)
- Posting a Radiation Area sign outside the work space
- Issuing all workers TLD badges before beginning work
Correct answer: Using local exhaust ventilation (LEV) or a glove box to capture contaminants at the source
Local exhaust ventilation captures airborne contamination at the point of generation before it disperses, providing the most effective source-control engineering measure.
NRRPT Decontamination & Exposure Prevention 5
A Contamination Area posting requires surveys to be performed at what minimum frequency under typical NRC-licensed facility procedures?