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

다국어 초록 (Multilingual 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 (Reference)

• 1 박장근, "수중 방사선모니터링 시스템의 성능평가를 위한 검출기의수중 내 유효검측거리 및 최저검출농도 산출" (사)한국방사선산업학회 12 (12): 11-14, 2018
• 2 오대민, "방사성 동위원소를 이용한 제염제 혼합확산장치의 유동특성분석" 대한환경공학회 39 (39): 282-287, 2017
• 3 이길용, "극 저준위 액체섬광계수기를 이용한 지하수 중 라돈(222Rn) 측정법 연구" 한국지하수토양환경학회 11 (11): 59-66, 2006
• 4 Knoll GF, "Radiation Detection and Measurement" John Wiley & Sons, Inc 321-364, 2011
• 5 Zeng Z, "Optimization of an underwater in-situ LaBr3 : Ce spectrometer with energy self-calibration and efficiency calibration" 121 : 101-108, 2017
• 6 Zhang Y, "Monte Carlo simulation of a NaI(Tl)detector for in situ radioactivity measurements in the marine environment" 98 : 44-48, 2015
• 7 Pelowitz DB, "MCNP6TM USER’S MANUAL Version 1.0"
• 8 Currie LA, "Limits for qualitative detection and quantitative determination application to radiochemistry" 40 (40): 586-593, 1986
• 9 NISA, "INES (the International Nuclear and Radiological Event Scale) Rating on the Events in Fukushima Daiichi Nuclear Power Station by the Tohoku District - off the Pacific Ocean Earthquake" 2011
• 10 Vlastou R, "Determination of marine gamma activity and study of the minimum detectable activity(MDA)in 4pi geometry based on Monte Carlo simulation" 165 : 159-168, 2010
• 11 OECD-NEA, "CHERNOBYL: Assessment of Radiological and Health Impacts"
• 12 Wu Y, "CAD-based Monte Carlo Program for Integrated Simulation of Nuclear System SuperMC" 82 : 161-168, 2015
• 13 Wu Y, "CAD-based Interface Programs for Fusion Neutron Transport Simulation" 84 : 1987-1992, 2009
• 14 Tsabaris C, "An autonomous in situ detection system for radioactivity measurements in the marine environment" 66 : 1419-1426, 2008