D-T中子诱发贫化铀球壳内裂变率分布实验  

Experimental study on fission reaction rate induced by D-T neutron in depleted uranium shell

作　　者：韩子杰[1] 朱通华[1] 鹿心鑫[1] 秦建国[1] 王玫[1] 蒋励[1] 杨波[2] Han Zi-Jie;Zhu Tong-Hua;Lu Xin-Xin;Qin Jian-Guo;Wang Mei;Jiang Li;Yang Bo(Institute of Nuclear Physics and Chemistry,China Academy of Engineering Physics,Mianyang 621900,China;Institute of Applied Physics and Computational Mathematics,China Academy of Engineering Physics,Beijing 100094,China)

机构地区：[1]中国工程物理研究院核物理与化学研究所,绵阳621900 [2]中国工程物理研究院北京应用物理与计算数学研究所,北京100094

出　　处：《物理学报》2019年第15期199-205,共7页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:11575165,11775200);国家磁约束核聚变能发展研究专项(批准号:2015GB108006)资助的课题~~

摘　　要：中子诱发裂变反应率是表征和检验中子在材料中的输运、裂变放能等过程的重要物理量.贫化铀球壳裂变反应率径向分布数据,可为铀核数据宏观检验及研究裂变放能与贫化铀球壳厚度的关系提供数据支持.本文设计了内径为13.1 cm,外径分别为18.10,19.40,23.35,25.40,28.45 cm的五种不同厚度的贫化铀球壳组合装置;利用位于球壳中心的氘氚中子源轰击贫化铀球壳装置,中子产额约为3×1010-4×1010s-1;在"赤道"平面与入射氘束成45°方向测量裂变反应率随径向分布的情况.为了克服裂变室和俘获探测器等自身对模型和中子场的扰动,本文选择与装置材料相同的贫化铀材料作为活化探测器,以活化探测器中的裂变碎片143Ce发射的γ射线作为测量对象,通过HPGe探测器测量的γ射线数,基于143Ce裂变产额数据反推裂变反应率.通过实验获得了贫化铀球壳内的裂变率及其径向分布规律,裂变反应率和相对标准不确定度分别位于5.28×10-29-7.58×10-28之间和6%-11%之间.基于蒙特卡罗程序和ENDF/BVI.8数据库完成了模拟计算,并与实验结果进行了对比分析,两者在不确定度范围内一致.Fission reaction rate is an important index for validating and checking the neutron transportation and fission power in nuclear engineering.The experimental data can be used in benchmark validation of cross sections,and in studying the correlation of fission power with the thickness of uranium sphere shell.There are five assemblies of depleted uranium shells used in this work,the inner radii of which are all fixed at 13.1 cm,while their outer radii are 18.1,19.4,23.35,25.4 and 28.5 cm,respectively.The D-T neutron source is generated in the center of the assemblies,the yield of which is about 3×10^10-4×10^10 s^–1.In horizontal plane across the center of the assemblies,the fission rates at positions along the radial direction are measured in the direction with 45°inclining with respect to the incident D^+beam.Due to the disturbance to assemblies and neutron field,the activation foil of uranium is a suitable choice rather than fission chamber or capture detector.The material of activation foil is the same as that in the experimental assemblies.Considering the accurate fission yield of 143Ce,the objective nuclides are selected.The total fission yield of 143Ce is contributed by 238U and a little 235U.For calculating the total fission yiled of 143Ce,the neutron energy range of 0-15 MeV is divided into eight subranges.By measuring the 293 keV gamma rays from the fission product 143Ce in activation foils with a TRANS-SPEC-DX100 HPGe detector,with a relative efficiency 40%,the fission rates and the trends at positions along the radial direction in the five assemblies are obtained based on the 143Ce fission product yield.The fission rate ranges from 5.28×10^–29 to 7.58×10^–28 sn^-1·nuclide^–1,with the relative uncertainty in a range from 6% to 11%.The Monte Carlo transport code MCNP5 and continuous energy cross section library ENDF/BV.8 are used for analyzing the fission rate distribution in the assemblies,and the experiemtal configuration,including the wall of the experimental hall is described in detail in

关 键 词：贫化铀 裂变率 143Ce 裂变产额 

分 类 号：O571.5[理学—粒子物理与原子核物理]