DEVELOPMENT OF A NEW DETECTOR SYSTEM TO EVALUATE POSITION AND ACTIVITY OF PLUTONIUM PARTICLES IN NASAL CAVITIES

Area of Science:

• Nuclear Engineering
• Radiation Detection and Measurement
• Occupational Health and Safety

Background:

• Plutonium dioxide (PuO2) poses inhalation risks in nuclear facilities, potentially causing lung cancer.
• Current methods for assessing PuO2 intake, like nasal smears, lack quantitative accuracy.
• Direct measurement of plutonium (Pu) activity in the nasal cavity is needed for precise internal dose assessment.

Purpose of the Study:

• To develop and evaluate a novel nasal monitor for direct, quantitative measurement of PuO2 activity.
• To enable accurate estimation of internal exposure dose in workers handling plutonium.
• To address the lack of suitable alpha-particle detectors for in-situ nasal cavity measurements.

Main Methods:

• Designed a bar-shaped detector using prismatic acrylic light guides and a ZnS(Ag) scintillator.
• Employed Silicon Photomultiplier (SiPM) arrays as the photodetector.
• Tested the nasal monitor by measuring actual PuO2 particles in simulated nasal cavities.

Main Results:

• The nasal monitor was successfully inserted into nasal cavities, providing Pu activity distribution.
• Achieved average 4-pi efficiencies of 11.4% (left) and 11.6% (right).
• Demonstrated negligible interference from Cesium-137 and Strontium-90, with measurement differences within 4.0% compared to standard counters.

Conclusions:

• The developed nasal monitor provides direct and quantitative Pu activity measurement.
• It is suitable for estimating internal exposure doses in workers.
• This technology offers a significant advancement over existing methods for plutonium contamination monitoring.