快中子辐照^(232)ThO_2样品生成^(233)U的产生率及^(232)Th俘获反应平均截面的测量  

Measurement of the generation ratio of ^(233)U and the average radiation capture cross section of ^(232)Th with ^(232)ThO_2 irradiated by fast neutrons

作　　者：王强[1] 曾丽娜[1] 艾自辉[1] 宋凌莉[1] 谢奇林[1] 郑春[1] 龚建[1] 

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

出　　处：《核技术》2014年第3期59-64,共6页Nuclear Techniques

基　　金：国家自然科学基金(No.91326104)资助

摘　　要：使用快中子辐照ThO2样品,测量233Pa的特征γ射线得到232Th发生俘获反应后233U产生率及俘获反应平均截面,利用ENDFB-VII.1、CENDL-3.1、JENDL-4.0、BROND2.2数据库截面数据算得232Th俘获反应平均截面,并与实验结果进行了比较。入射快中子注量为2.99×1013 cm-2时,233U产生率为4.01×10-12,相对标准不确定度为6.1%。232Th俘获平均反应截面为134.3 mb,相对标准不确定度为12.4%,由CENDL-3.1计算的俘获反应平均截面相比实验结果小18.5%。Background： Thorium-Uranium cycle plays an important role in the future＇s power production technology. Nuclear data involved are urgently needed for engineering design and other purposes since there are obvious differences between the existing evaluated data. Macroscopic neutron integral experiment can be used as a good tool to survey the confusion. Purpose： Macroscopic neutron integral experiment based on radioactive method was carried out to measure the generation ratio of 233U nuclide and the average radiation capture cross section of 232Th while a ThO2 sample was irradiated by fast neutrons leakage from a fast critical facility. We expect that these data can be used as a reference for the research of Th-U cycle. Methods： Radiation capture reactions of 232Th nuclides occur when the nuclides are irradiated by neutrons. 233U nuclides will be generated after two cascade decays by emitting beta rays from the activation products, which are 233Th nuclides. The ThO2 sample was prepared as a slice of 20 mm× 10 mm from 0.743 36-g ThO2 powders of 99.9% enriched. The neutron flux was measured by activation method which was 4.07× 10^9 cm-2.s-1 at the sample＇s irradiation position while the facility worked at the power level of 180 watts. The leakage neutrons＇ energy distribution was calculated by MC method and it is very close to the fission spectrum with the averaged energy of 1.42 MeV. After irradiation and then a period of cooling time the gamma rays emitted from the sample were measured by an HPGe spectrometer which had been pre-calibrated. From these data the activity of 233pa was calculated and then the generation ratio of 233U and the average radiation capture cross section of 232Th were calculated. The measured average radiation capture cross section was compared with the cross sections calculated based on the ENDFB-VII.1, CENDL-3.1, JENDL-4.0, BROND2.2 databases. Results： The measured generation ratio of 233U was 4.01×10^-12 with an urtcertainty of 6.1% while the neutron fluence at the irradiatio

关 键 词：钍铀循环 核燃料分析 临界装置 活度 平均截面 

分 类 号：TL272[核科学技术—核燃料循环与材料]