基于贝叶斯更新方法的^(235) U热中子独立裂变产额协方差估计  

Covariance Estimation of ^(235) U Thermal Neutron Independent Fission Yields Based on Bayesian Updating Method

作　　者：王毅箴 崔梦蕾 郭炯 邬颖杰 刘保坤 李富 WANG Yi-zhen;CUI Meng-lei;GUO Jiong;WU Ying-jie;LIU Bao-kun;LI Fu(Institute of Nuclear and New Energy Technology,Collaborative Innovation Center of Advance Nuclear Energy Technology,Key Laboratory of Advanced Reactor Engineering and Safety of Ministry of Education,Tsinghua University,Beijing 100084,China)

机构地区：[1]清华大学核能与新能源技术研究院,先进核能技术协同创新中心,先进反应堆工程与安全教育部重点实验室,北京100084

出　　处：《现代应用物理》2021年第1期13-19,共7页Modern Applied Physics

基　　金：国家重大科技专项资助项目(2018ZX06902013);国家自然科学基金资助项目(11375099,11505102)。

摘　　要：基于贝叶斯更新方法,利用ENDF/B-VII.1数据库中^(235) U热中子累积裂变产额的不确定度及裂变系统的物理约束条件,对^(235) U热中子独立裂变产额协方差矩阵进行了估计与分析。结果表明,多数核素独立裂变产额的不确定度与更新前相比均减小约30%,在独立裂变产额较大的两峰处,独立裂变产额不确定度减小的幅度较大。根据更新后的独立裂变产额协方差矩阵,分析认为,多数核素的独立裂变产额间存在弱相关性,相关系数小于0.25,且多数为负相关。其中,由累积裂变产额不确定度引起的相关性多集中在各个独立裂变产额的质量链内,而由裂变系统的物理约束引起的相关性多集中于独立裂变产额较大的两峰处。Based on Bayesian updating method,the covariance matrix of ^(235) U thermal neutron independent fission yields in ENDF/B-VII.1 database is estimated by using the uncertainty of the cumulative fission yields of ^(235) U and the physical constraints of the fission system.The results show that the uncertainty of the independent fission yield of most nuclides decrease by about 30%compared with that before update,and these decreases are significant in the fission product yields residing in the two-humped part of independent fission product mass yields distribution.Based on the updated independent fission yield covariance matrix,it is found that there is a weak correlation between the independent fission yields of most nuclides,the correlation coefficient is less than 0.25,and most of them are negative correlation.Among them,the correlation caused by the uncertainty of the cumulative fission yields is concentrated in the mass chain of each independent fission yield,while the correlation caused by the physical constraints of the fission system is focused on the two-humped part of the independent fission yields mass distribution.

关 键 词：独立裂变产额 ENDF/B-VII.1 贝叶斯更新方法 协方差数据 不确定性分析 

分 类 号：TL329[核科学技术—核技术及应用]