体素效率加权平均法求解核废物桶SGS效率

A Calculation Method of SGS Efficiency for Nuclear Waste Drum Based on the Weighted Average of Voxel Efficiency

采用了一种基于体素效率加权平均的核废物桶SGS效率数值计算方法,通过空间点源效率函数确定断层中体素的无衰减效率,计算体素发射的γ射线进入探测器过程中在桶内介质中的衰减长度,结合介质的线衰减系数确定体素的衰减效率,对断层中所有体素的衰减效率进行加权平均,实现断层的衰减效率计算。结果表明:桶内^(137)Cs核素的活度重建偏差为-32.53%~19.38%,实验验证了该效率数值计算方法的有效性和准确性。

Segmented gamma scanning(SGS)is a technique to determine the isotopic composition and activity for radioactive waste drum.Efficiency affects the accuracy of SGS analysis and it’s a complex and difficult point.In this work,A numerical calculation method of SGS efficiency for nuclear waste drum based on the weighted average of voxel efficiency is presented to calculated the efficiency.Every segment’s efficiency is determined by the space efficiency of voxel and linear attenuation coefficient obtained by SGS transmission measurement.Waste drum sample that consists of alumina silicate,wood,a point sources ^(137)Cs are experimental measured on the SGS system.The activity is reconstructed with ART and MLEM algorithms.The results show the relative error of reconstructed activity is-32.53%~19.38%when the distribution of isotope is extremely heterogeneous as a single point source in drum.It is indicated that this method is effective and feasible.