수중 방사선모니터링 시스템의 성능평가를 위한 계측기의 수중 내 농도환산인자 및 최저검출농도 산출
Determination of Activity Conversion Factor and Minimum Detectable Activity for Underwater Radiation Monitoring System
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An underwater radiation monitoring system has been developed using a NaI (Tl) detector for the potential radioactive contamination of drinking water by 137Cs and 131I radioisotopes. In this study, experiments and simulations were carried out using the detector to evaluate the minimum detectable activity (MDA) and conversion factor (converting counts into Bq·L-1) of radioisotopes 137Cs and 131I. For the experiments, a waterproof system with the detector was located at the center of a water tank into which 68Ga was homogeneously diffused instead of 137Cs and 131I due to a radwaste problem, and detection counts were recorded for every 5 min. Monte Carlo simulations were carried out for 68Ga with the same geometry as the experiment to compare with the experimental energy spectrum to obtain simulation calibration value, and simulations were then performed for 137Cs and 131I to calculate the conversion factor. From the simulations, the conversion factors were 1.74×10-2 and 1.30×10-2 (Bq·L-1)/count for 137Cs and 131I, respectively. From underwater radiation background data and the conversion factors, the MDA of 137Cs and 131I for the system were found to be 0.77 and 0.89 Bq·L-1, respectively.
Abstract
An underwater radiation monitoring system has been developed using a NaI (Tl) detector for the potential radioactive contamination of drinking water by 137Cs and 131I radioisotopes. In this study, experiments and simulations were carried out using the detector to evaluate the minimum detectable activity (MDA) and conversion factor (converting counts into Bq·L-1) of radioisotopes 137Cs and 131I. For the experiments, a waterproof system with the detector was located at the center of a water tank into which 68Ga was homogeneously diffused instead of 137Cs and 131I due to a radwaste problem, and detection counts were recorded for every 5 min. Monte Carlo simulations were carried out for 68Ga with the same geometry as the experiment to compare with the experimental energy spectrum to obtain simulation calibration value, and simulations were then performed for 137Cs and 131I to calculate the conversion factor. From the simulations, the conversion factors were 1.74×10-2 and 1.30×10-2 (Bq·L-1)/count for 137Cs and 131I, respectively. From underwater radiation background data and the conversion factors, the MDA of 137Cs and 131I for the system were found to be 0.77 and 0.89 Bq·L-1, respectively.
참고문헌 (14)
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