DT中子下聚乙烯球中^(232)Th(n,2n)反应率的测量与分析  

Measurement and analysis of the ^(232)Th(n,2n) reaction rate in a polyethylene shell with DT neutrons

作　　者：刘竹君 羊奕伟[1] 郑雷 刘荣[1] 杨朝文[2] 王玫[1] LIU Zhujun;YANG Yiwei;ZHENG Lei;LIU Rong;YANG Chaowen;WANG Mei(Institute of Nuclear Physics and Chemistry, China Academy of Engineering Physics, Mianyang 621900,China;Department of Nuclear Engineering and Technology, College of Physical Sciences and Technology, Sichuan University,Chengdu 610064,China;Department of Engineering Physics, Tsinghua University, Beijing 100084, 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]四川大学物理科学与技术学院核工程与核技术系,成都610064 [3]清华大学工程物理系,北京100084

出　　处：《核技术》2018年第6期48-53,共6页Nuclear Techniques

基　　金：国家自然科学基金(No.11505164);中国工程物理研究院院长基金(No.YZJJLX2016003);中子重点实验室基金(No.2015BA02)资助~~

摘　　要：^(232)Th(n,2n)数据对于钍基反应堆研究十分重要,有必要针对其开展中子积分实验,因此,建立了聚乙烯球基准宏观装置,利用活化法在DT中子源下开展了测量^(232)Th(n,2n)反应率的中子积分实验。实验中分别采用了钍粉末以及钍片两种样品形态,以消除实验样品状态对实验结果的影响,将样品置于与D离子入射方向成0°的位置进行辐照,利用金硅面α探测器进行中子产额监测以及中子注量波动监测。辐照结束后,利用高纯锗谱仪离线测量反应产物231Th发射的能量为84.2 ke V的γ射线,得到^(232)Th(n,2n)反应率值。同时使用MCNP(Monte Carlo N Particle Transport Code)在数据库ENDF/B-Ⅶ.1、ENDF/B-Ⅶ.0、JENDL4.0下对实验进行了精确模拟,数据库JENDL4.0下的反应率计算结果与实验符合较好。[Background] The ^232Th（n,2n） reaction dominates the neutron generation, so the validity of the cross section data is significant in the thorium based reactor. [Purpose] In order to provide the data reference for the design of thorium based reactor, an integral experiment to measure the ^232Th（n,2n） reaction rate was carried out using the activation method in a polyethylene shell with DT neutrons. [Methods] In the experiment, thorium samples were arranged in the 0° direction to the incident D^＋ beam, and a Au-Si surface barrier detector was used to monitor the neutron yield and the fluctuation of neutron flux. [Results] After irradiation, the 84.2 keV γ ray emitted from ^231 Th was measured by HPGe spectrometer, and the ^232Th（n,2n） reaction rate was then obtained. The thorium sample was in foil and powder respectively to eliminate the effect of the sample condition. Simultaneously, the experiment was simulated precisely using Monte Carlo N Particle Transport Code（MCNP） code in the ENDF/B-Ⅶ.1, ENDF/B-Ⅶ.0, and JENDL4.0 libraries. [Conclusion] The calculated values in the JENDL4.0 were in good agreement with the experimental ones, which can provide reference for the design of thorium based reactors.

关 键 词：^232Th(n 2n)反应率 中子积分实验 DT中子 MCNP 活化法 

分 类 号：TL99[核科学技术—核技术及应用]