原子能科学技术 ›› 2022, Vol. 56 ›› Issue (5): 849-859.DOI: 10.7538/yzk.2022.youxian.0020

• 核数据实验测量研究 • 上一篇    下一篇

基于D-T中子源的板状铌样品的评价数据基准检验实验

赵齐;聂阳波;丁琰琰;任杰;阮锡超;胡志杰;徐阔之   

  1. 中国原子能科学研究院 核数据重点实验室,中国核数据中心,北京102413;兰州大学 核科技与技术学院,甘肃 兰州730000
  • 出版日期:2022-05-20 发布日期:2022-05-20

Benchmark Experiment on Slab Nb with D-T Neutron for Validation of Evaluated Nuclear Data

ZHAO Qi;NIE Yangbo;DING Yanyan;REN Jie;RUAN Xichao;HU Zhijie;XU Kuozhi   

  1. China Nuclear Data Center, Key Laboratory of Nuclear Data, China Institute of Atomic Energy, Beijing 102413, China;School of Nuclear Science and Technology, Lanzhou University, Lanzhou 730000, China
  • Online:2022-05-20 Published:2022-05-20

摘要: 利用中国原子能科学研究院核数据国家重点实验室的脉冲化氘氚聚变中子源产生的145 MeV单能中子,通过飞行时间法,测量了5、10、15 cm厚度板状铌(Nb)样品在与60°和120°两个方向上的泄漏中子飞行时间谱。利用蒙特卡罗模拟软件MCNP4C进行了泄漏中子飞行时间谱的模拟计算,分别获得了CENDL31、ENDF/BⅧ0和JENDL40 3个数据库中Nb评价数据的模拟结果。通过各数据库不同能区的模拟结果与实验结果的比值(C/E),对3个数据库中93Nb与145 MeV中子作用的角分布和双微分截面等相关评价数据进行了检验,重点分析了CENDL31库的数据。结果表明,CENDL31数据库的模拟结果在弹性散射能区、非弹性散射能区以及(n,2n)反应能区与实验结果均存在一定的偏差。而JENDL40数据库除在120°弹性散射能区有高估现象,其他能区的模拟结果与实验结果均符合较好。ENDF/BⅧ0数据库的模拟结果除在60°方向弹性散射峰偏低外,其他能量范围的模拟结果均高于实验。

关键词: 氘氚中子源, 飞行时间法, Nb, MCNP-4C, CENDL-3.1, C/E

Abstract: In the fusion reactor, the first wall, blankets and superconducting magnets are directly exposed to 14.5 MeV neutrons produced by fusion reaction. Some of the characteristics of Nb metal such as high melting point, good thermal conductivity and low neutron capture cross section make Nb often used in these parts of reactor. Therefore, the quality of the evaluated nuclear data of Nb is required more accurate to ensure the safety and economy in the process of the fusion reactor working. Benchmark experiments are an important way to test and evaluate the reliability of data. A benchmark experiment on Nb was carried out with 145 MeV DT neutron source in China Institute of Atomic Energy. Slab Nb with thickness of 5 cm, 10 cm and 15 cm was selected as samples. For each thickness of Nb, the leakage neutrons from 08 MeV to 16 MeV were measured using the timeofflight method in the 60° and 120° directions. The Monte Carlo neutron transport code MCNP4C was used to simulate the leakage neutron spectra under the same experimental conditions, the Nb data was retrieved from CENDL-3.1, ENDF/B-Ⅷ.0 and JENDL-4.0 evaluation data libraries. The whole time of flight spectrum was divided into the parts contributed by four reaction channels including (n, el), (n, inl)D, (n, inl)C, and (n, 2n). The simulation integral value of each part was compared with the experimental integral value, and the C/E was obtained as the standard to verify the reliability and accuracy of the relevant data. As the results of the benchmark experiment on Nb, it can be found that: Except a little overpredict at the simulation result of elastic scattering at 120°, the Nb nuclear data of the JENDL40 data library is in good agreement with experiment results. One of the problems of CENDL31 library are that it gives too large discrete inelastic scattering cross section. The other problem may be that the secondary neutron energy spectrum given by continuous level of inelastic scattering and (n, 2n) reaction is soft. The simulation results of the ENDF/B-Ⅷ.0 data library make a huge difference. It can be seen from the comparison results that the cross section of the energy spectrum in the discrete inelastic scattering part is high and the energy spectrum given in the continuum inelastic scattering part is also problematic. The discrepancies of elastic scattering peak between 60° and 120° are considered as caused by the wrong angular distribution, especially the underestimate at 60°. So the ENDF/BⅧ.0 library has a lot to improve. In a conclusion, these three libraries are all need to be improved to get more accurate data.

Key words: D-T neutron source, time-of-flight method, Nb, MCNP-4C, CENDL-3.1, C/E