방사성 금속폐기물 오염도 측정 및 분류 시스템 구축을 위한 검출기 성능평가

Abstract

The purpose of this study is to evaluate detector characteristics like evaluation ofthe dependence on linearity, accuracy, and directionality by utilizing a gamma-ray standardbenchmark irradiation system which was built to test the radial performance of the LBC(Lanthanum BromoChloride) detector among the main components of the radioactive metalwaste contamination level measurement and classification system that is to be developed in thisstudy. The detector characteristics were evaluated through benchmark irradiation by using 60Co,137Cs, 241Am mounted on a gamma-ray standard irradiation equipment. For linearity, evaluatinglinearity from the 3,000 mm or greater interval was verified to be better than evaluating linearityfor the entire section and R-square value for each source was verified to be 60-Co: 0.999 904,137-Cs: 0.999 923, 241-Am: 0.999 700. For the reproducibility, the average coefficient value foreach source was verified to be 60Co: 943 282.1, 137Cs: 416 943.8, 241Am: 856 398.1, and the relativestandard deviation value for each was verified to be 60Co: 0.10, 137Cs: 0.14, 241Am: 0.09. Finally,for the response of angle, a change in relative responsiveness from 1.057~1.205 in the horizontaldirection was verified. While it was satisfied within a 20% range for most directions, there was a0.5% difference in the - 75° area. Through this result, we aim to contribute to the improvementof safety reliability for nuclear decommissioning by securing a lower bound for detection that issufficiently low by enhancing the measurement efficiency by building a measurement system thatutilizes multiple scintillators for rapid measurement and classification of large volume of metalwaste in the future and by securing easiness of self-disposal by solving the representative sampleproblem through radioactivity homogeneity evaluation.