热中子屏蔽性能测试平台设计优化及影响因素分析  

Design optimization and influencing factor analysis of performance testing platform for thermal neutron shielding

作　　者：王豫庆 李多宏 张荣华 贾文宝[2] 赵冬[2] 谭西早 朱秋平 周志波 黎春 WANG Yuqing;LI Duohong;ZHANG Ronghua;JIA Wenbao;ZHAO Dong;TAN Xizao;ZHU Qiuping;ZHOU Zhibo;LI Chun(State Nuclear Security Technology Center,Beijing 102401,China;Nanjing University of Aeronautics and Astronautics,Nanjing 211106,China)

机构地区：[1]国家核安保技术中心,北京102401 [2]南京航空航天大学,南京211106

出　　处：《核技术》2024年第9期23-34,共12页Nuclear Techniques

摘　　要：材料热中子屏蔽性能测试是评价新型中子屏蔽材料屏蔽性能的重要手段,并为材料的改进和应用提供重要指导,在中子辐射屏蔽领域具有重要的研究意义。目前,基于同位素中子源的纯热中子场不易获得,而常用的热中子探测器能量响应范围较宽,导致材料的热中子屏蔽性能测试结果的准确性较差。针对此问题,提出一种基于“镉差法”的热中子屏蔽性能方法并建立相应的测试平台。该平台基于252Cf同位素中子源与3He正比计数器,以误差最小化为设计原则,利用蒙特卡罗模拟方法对该平台的辐射屏蔽体、中子慢化体、准直体及探测器屏蔽体的材料及尺寸进行优化。对常用辐射防护材料的热中子屏蔽性能进行测试以验证测试方法可行性与准确性,并对探测系统类型、中子源强度、探测系统远近距离、探测系统偏移及中子源类型5种影响因素进行了实验分析。研究表明,该平台的材料热中子屏蔽性能测试结果重复性高、再现性强,可实现对材料热中子屏蔽性能的准确测试。[Background]With the development of materials science and technology,more and more novel neutron shielding materials have been studied and prepared.The test of thermal neutron shielding performance of materials is an important measure of evaluating the shielding performance of novel neutron shielding materials,and provides important guidance for the improvement and application of materials.Special attention has been paid to the thermal neutron shielding properties of some thin materials,such as radiation protection fibers,shielding coatings,radiation protection rubber,composites with thermal neutron absorbers.At present,it is not easy to obtain pure thermal neutron field based on isotope neutron source,and the commonly used thermal neutron detector has a wide energy response range,and there is no unified test standard,hence the accuracy of the test results of thermal neutron shielding performance of materials needs to be further improved.[Purpose]This study aims to propose an accurate method for testing the thermal neutron shielding properties of materials and to design a corresponding test platform.[Methods]A thermal neutron shielding performance testing method based on the"cadmium filter method"was proposed and a corresponding testing platform was established.Firstly,the platform was based on a 252Cf isotope neutron source and a 3He proportional counter,with the design principle of minimizing errors.Then,Monte Carlo simulation method was used to optimize the materials and dimensions of the radiation shield,neutron moderator,collimator,and detector shield of the platform.The system error caused by the testing principle was reduced by further optimizing the cadmium filter method,and a collimating neutron beam launcher was designed to improve the collimation effect of the neutron beam,increase the thermal neutron fluence rate and thermal neutron share,and reduce the random error and the system error caused by the system design.Finally,the thermal neutron shielding performance of the materials commonly used in the

关 键 词：热中子屏蔽性能 能量响应 镉差法 蒙特卡罗模拟 

分 类 号：TL99[核科学技术—核技术及应用]