몬테카를로 시뮬레이션에서의 다양한 환경 샘플에 대한 Marinelli 비이커 측정 및 자기 흡수 보정과 적용
Marinelli Beaker Measurement and Self Absorption Correction and Application for Various Environmental Samples in Monte Carlo Simulation
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검출기의 구조를 PENELOPE의 코드를 사용하여 전산모사 하였다. 표준혼합시료(450, 1,000㎖)를 사용하여 다양한밀도와 높이에 따른 저에너지(59.54 keV)부터 고 에너지(1,836.05)에 대한 측정효율과 PENELOPE 전산모사에서 구한효율을 비교하였으며, 또한 자체흡수에 대한 효율을 보정하여 다양한 환경시료에 적용하여 검출하한치를 알아보고자한다. 표준혼합선원의 전체에너지 피크효율 값을 적용하여 높이에 따른 효율변화를 측정치와 PENELOPE의 전산모사값과 비교하였다. 여기서 구한 값들을 자체흡수 보정하여 구한 효율을 실제 환경시료에 적용하여 검출하한치 값들을구하였다. 밀도보정인자는 밀도가 0.4 g/㎤에서 241Am(59.54 keV)의 밀도보정인자는 1.15, PENELOPE 전산모사에서는1.153, 137CS(661.66 keV) 에서는 1.06 g/㎤, PENELOPE 전산모사에서는 1.064, 88Y(1,836.04 keV)에 대한 밀도보정인자는 1.03, PENELOPE 전산모사에서는 1.033으로 불확도는 1% 이내에서 잘 일치함을 확인하였다. 환경 시료의 밀도에따른 방사능 농도는 시료량이 많을수록, 측정시간이 증가할수록 MDA(Minimum Detectable Activity) 값이 감소함을확인할 수 있었다.
Abstract
The structure of the actual detector was computed using the code of the PENELOPE. Using the standard mixed sources (450, 1,000㎖), compare the effectiveness of each energy according to various densities and height of the PENELOPE computer simulation, and calculate the effectiveness of the various environmental specimens and apply them to various environmental specimens to determine the lower limit. The values obtained by the obtained value were obtained by applying the obtained efficiency to the actual environmental specimens and obtaining the lower limit values. The density correction factor is 1.155 g of the density correction factor of 0.4 g/㎤ (59.54k eV), 1.153 (661 keV), 1.06 g/㎤ 1.064 (1,836.04k eV), 1.03, and 1.033. It was confirmed that the radioactivity concentration of environmental samples decreased as the amount of specimen was measured increases, and the MDA value decreased as time measured increases.
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