基于正电子衰变核素的符合探测效率研究  

Research on Coincidence Detection Efficiency Based on Positron Decay Nuclides

作　　者：卓祥林 青先国[1] 杨振雷 包超[1] 蒋天植 李进 卢佳玮 Zhuo Xianglin;Qing Xianguo;Yang Zhenlei;Bao Chao;Jiang Tianzhi;Li Jin;Lu Jiawei(Science and Technology on Reactor System Design Technology Laboratory,Nuclear Power Institute of China,Chengdu,610213,China)

机构地区：[1]中国核动力研究设计院核反应堆系统设计技术重点实验室,成都610213

出　　处：《核动力工程》2024年第1期246-252,共7页Nuclear Power Engineering

摘　　要：为了降低一回路压力边界冷却剂泄漏监测的测量下限,本文基于正电子衰变核素开展了符合探测效率研究。为了提高符合探测效率,采用蒙特卡罗程序Geant4对符合探测装置中的粒子输运过程进行了仿真模拟分析,研究了符合探测装置结构和探测器属性对符合探测效率的影响。研究结果表明:通过在滤纸源两侧添加β+吸收层可明显提升符合探测效率,采用0.5 mm厚度的铝或0.2 mm厚度的铁作为β+吸收层时符合探测效率最佳;由于不同类型探测器的能量分辨率存在差异,因此不同类型探测器达到最佳符合探测效率时的能量窗系数不同,NaI(Tl)最佳能量窗系数为14%,BGO最佳能量窗系数为26%,LaBr3(Ce)最佳能量窗系数为7%。本研究成果可为以18F核素为放射性示踪剂的一回路压力边界泄漏监测系统探测装置结构设计及符合判断逻辑设计提供参考。In order to reduce the measurement lower limit of the primary pressure boundary leakage monitoring,the coincidence detection efficiency based on positron decay nuclides has been studied.In order to improve the coincidence detection efficiency,the particle transport process in the coincidence detection device has been simulated and analyzed by Monte Carlo code Geant4,and the effects of coincidence detection device structure and detector properties on the coincidence detection efficiency have been studied.The research results show that:addingβ+absorbing layers on both sides of the filter paper can significantly improve the coincidence detection efficiency,and the optimal coincidence detection efficiency is obtained when 0.5mm Al or 0.2mm Fe is used asβ+absorbing layer;due to the difference in energy resolution of different types of detectors,different types of detectors have different energy window coefficients for reaching the optimal detection efficiency.The optimal energy window coefficients of NaI(Tl),BGO and LaBr3(Ce)are 14%,26%and 7%respectively.The results of this research can provide a reference for the structural design of the detection device and the coincidence judgment logical design of the primary pressure boundary leakage monitoring system with 18F nuclide as the radioactive tracer.

关 键 词：一回路压力边界泄漏监测 符合探测效率 闪烁体探测器 正电子源 GEANT4 

分 类 号：TL812[核科学技术—核技术及应用]