基于随机抽样的衰变热不确定度量化研究  

Decay Heat Uncertainty QuantificationBased on Stochastic Sampling Method

作　　者：马纪敏[1] 郭海兵[1] 黄洪文[1] MA Jimin;GUO Haibing;HUANG Hongwen(Institute of Nuclear Physics and Chemistry,China Academy of Engineering Physics,Mianyang 621900,China)

机构地区：[1]中国工程物理研究院核物理与化学研究所,四川绵阳621900

出　　处：《原子能科学技术》2024年第6期1280-1286,共7页Atomic Energy Science and Technology

基　　金：国家磁约束核聚变能发展研究专项(2022YFE03160003)。

摘　　要：为研究核数据引起的核素存量及导出量的不确定度,在自主程序GNET上实现了基于随机抽样的不确定度量化方法。利用贝叶斯更新方法获得裂变产物独立产额的协方差数据,弥补裂变产额协方差数据缺失。对热中子引起的235U一次裂变后衰变热不确定度进行了计算。结果表明,裂变产物产额的不确定度贡献占主要部分。该算例表明GNET程序具备了核素存量的不确定度量化功能。Nuclear data are the important source of uncertainties that affect nuclide inventory analysis.The new domestic code GNET(general nuclear engineering tool)has been developed to study the uncertainties of nuclide inventory and relevant quantities due to nuclear data.GNET is a pure Python3 package devoted to promote and accelerate the application in nuclear data,nuclide inventory,reactor physics data analysis,and so on.The code makes use of HDF5 format file and provides several auxiliary library files.The uncertainty quantification method in GNET is based on stochastic sampling.Nuclear data and their uncertainties such as decay data,fission yield and cross sections have been sampled to generate random library files.Then the application calculation with these files was performed.Finally,a statistical analysis of the response variables can be carried out to obtain mean values and their standard deviation.Uncertainties and covariance data in ENDF/B-Ⅶ.1 were analyzed.Nuclear data libraries lack fission product yield covariance data.To solve the problem,the Bayesian updating method was applied to obtain fission yield covariance.As one of state-of-art fission yield covariance generation methodologies,the Bayesian updating method is an adjustment technique which updates the prior data with new knowledge.The covariance matrix of independent fission yields has been generated using consistency with cumulative fission yields,binary fission,mass and charge conservations.In this paper,the decay heat uncertainty quantification for a burst thermal fission of 235U was investigated with GNET.Decay heat was calculated by summation method.The result of decay heat for a burst thermal fission of 235U was compared with FISPACT-Ⅱresults,ORNL and Tobias’compiled data.It is shown that GNET result is consistent with FISPACT-Ⅱand measurement results.A large number of calculations were used to calculate decay heat uncertainty due to uncertainties of decay constant,branching ratio,decay energy and IFYs in ENDF/B-Ⅶ.1.The convergence of

关 键 词：不确定度量化 随机抽样 衰变热 协方差 贝叶斯更新方法 

分 类 号：TL329[核科学技术—核技术及应用]