NRRPT Contamination and Airborne Control 2 — Questions and Answers
Question 1: What is the primary purpose of a glove box in radiological work?
- Provide a ventilated enclosure to handle radioactive materials without direct contact (Correct answer)
- Store radioactive samples at controlled temperature
- Filter airborne particulates before release to the environment
- Monitor personnel dose during handling operations
Correct answer: Provide a ventilated enclosure to handle radioactive materials without direct contact
A glove box provides an enclosed, controlled environment allowing workers to manipulate radioactive materials through attached gloves without direct contact or exposure.
Question 2: Which instrument is most appropriate for detecting low-level tritium (H-3) air contamination?
- Geiger-Mueller detector
- Ionization chamber air monitor
- Liquid scintillation counter after air sample collection (Correct answer)
- Sodium iodide scintillation detector
Correct answer: Liquid scintillation counter after air sample collection
Tritium's very low-energy beta (18.6 keV max) cannot be detected directly in air; air samples are collected and analyzed by liquid scintillation counting.
Question 3: A smear survey shows 450 dpm/100 cm² of beta activity on an uncontrolled surface. What action is required per NRC guidelines?
- No action needed; below all limits
- Post a Caution - Radioactive Material sign and restrict access (Correct answer)
- Decontaminate immediately; the level exceeds the 5,000 dpm/100 cm² limit but not the emergency threshold
- Evacuate the area and notify the NRC immediately
Correct answer: Post a Caution - Radioactive Material sign and restrict access
NRC surface contamination limits for unrestricted areas are 1,000 dpm/100 cm² (beta/gamma); 450 dpm/100 cm² exceeds this, requiring posting and restriction.
Question 4: What does 'fixed' contamination mean in radiation protection?
- Contamination that has been formally documented in a survey record
- Radioactive material that cannot be removed from a surface by normal contact (Correct answer)
- Contamination permanently attached using a fixative spray
- Contamination of a fixed installation rather than portable equipment
Correct answer: Radioactive material that cannot be removed from a surface by normal contact
Fixed contamination is radioactive material bound to a surface that is not readily removable by wiping, contact, or normal operations.
Question 5: An airborne radioactivity area is defined as a location where airborne activity exceeds what DAC fraction?
- 0.1 DAC (Correct answer)
- 1 DAC
- 10 DAC
- 100 DAC
Correct answer: 0.1 DAC
Under 10 CFR 20.1003, an airborne radioactivity area exists where concentrations exceed 0.1 DAC or where a worker could receive an intake exceeding 12 DAC-hours in a week.
Question 6: Which ventilation design principle is most effective at preventing the spread of radioactive contamination from a hot cell to adjacent areas?
- Maintaining the hot cell at positive pressure relative to the corridor
- Maintaining the hot cell at negative pressure relative to the corridor (Correct answer)
- Using HEPA filtration on all supply air
- Exhausting air horizontally away from personnel
Correct answer: Maintaining the hot cell at negative pressure relative to the corridor
Negative pressure in the contaminated area ensures air flows inward from clean zones, preventing migration of contamination to adjacent areas.
Question 7: A worker's nasal smear after removing respiratory protection shows detectable activity. What does this indicate?
- The air sampling result was false-positive
- Potential respiratory tract deposition and possible internal contamination intake (Correct answer)
- The face seal was adequate but the filter was overloaded
- Background radiation affecting the detector
Correct answer: Potential respiratory tract deposition and possible internal contamination intake
Positive nasal smears indicate that radioactive material has been inhaled and deposited in the nasal passage, suggesting an internal contamination intake occurred.
NRRPT Contamination and Airborne Control 2
What is the primary purpose of a glove box in radiological work?