裂变产额的Z_(p)模型评价方法及燃耗不确定度分析  

Fission Yield Evaluation Method Based upon Z_(p) Model and Uncertainty Analysis in Burnup Calculation

作　　者：舒能川[1] 朱淑瑜 祖铁军[2] 金永利[1] 卢泽润 曹超维 宿阳 刘丽乐[1] 陈永静[1] 葛智刚[1] 刘萍[1] 黄小龙[1] 续瑞瑞[1] SHU Nengchuan;ZHU Shuyu;ZU Tiejun;JIN Yongli;LU Zerun;CAO Chaowei;SU Yang;LIU Lile;CHEN Yongjing;GE Zhigang;LIU Ping;HUANG Xiaolong;XU Ruirui(China Nuclear Data Center,Key Laboratory of Nuclear Data,China Institute of Atomic Energy,Beijing 102413,China;School of Nuclear Science and Technology,Xi’an Jiaotong University,Xi’an 710049,China)

机构地区：[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 [2]西安交通大学核科学与技术学院,陕西西安710049

出　　处：《原子能科学技术》2022年第5期927-936,共10页Atomic Energy Science and Technology

基　　金：国家自然科学基金(11790323,U1867213,12075183,11790320,11790324,11790325);稳定基础科研计划(WDJC-2019-09)。

摘　　要：裂变产额在核科学技术和核工程中有着重要的应用,发展可靠、高效的产额评价方法和相应燃耗计算不确定度分析方法,对于建立高质量的产额数据库具有重要的意义。本文根据裂变产物核衰变模式和衰变分支比,建立独立产额与累积产额的转换矩阵,用于Z_(p)模型的扩展,使之适用于独立产额和累积产额的统一描述,并以此建立了用于产额统一评价的拟合程序ZpFit。把ZpFit程序应用于中子诱发^(235)U裂变产物产额评价,获得了自洽的独立产额、累积产额和相应的协方差数据,并建立ENDF格式的中子诱发^(235)U裂变的产额数据库。在此基础上,计算了UAM燃耗基准题的TMI-1栅元的k_(inf)、重要核素原子核密度的不确定度,比对了本工作评价的产额数据和ENDF/B-Ⅷ.0评价库中产额数据传递给响应量的相对不确定度,结果基本一致,差异不大。Nuclear fission product yield(FPY)is an important data base for the research of nuclear energy and nuclear devices.The development of reliable and efficient yield evaluation methods is of great significance for the establishment of high-quality yield database.Previously,to obtain a FPY for a specific product,the related experimental data would be collected and analyzed to obtain the weighted average value as the recommended value.This method did not consider the physical relation among the yields of the precursor and daughter nuclides on the same mass chain.So a physical model is needed to describe the isobaric(with same mass)Z distribution,and could be used to evaluate the independent and cumulative yields simultaneously.Z_(p) model is a better method to describe the isobaric charge distribution since its physic mechanic is more certain.And to connect with the cumulative yields,the conversion matrix is deduced from the decay data,with which the cumulative yields could be calculated from independent yields on the same chain.Based upon the above idea,a fitting program named ZpFit was established for the unified evaluation of isobaric yields,and was applied to evaluate the yields of n+^(235)U fission.The related independent yield,cumulative yield and corresponding covariance data were obtained self-consistently and formed a yield database in ENDF format.For examples,the evaluations for yields of A=125,140 and 149 of n th+^(235)U fission were expressed in this paper.For A=125,the cumulative yields in literature have discrepancy,roughly could be grouped with higher and lower parts with the help of ZpFit codes.An experiment was carried out to clear this discrepancy by the ream in CIAE,the yield for 125 Sn is around 0.025,about 20%and 10%lower than the data in ENDF/B-Ⅷ.0 and JEFF-3.3,respectively,agrees with the lower group of the literature values.So finally,we got the fitted yields giving more weighting to the lower part.For A=140,the result shows that with the help of ZpFit,we could decide which yields are not rea

关 键 词：裂变产额评价 Z_(p)模型 n+^(235)U 不确定度分析 

分 类 号：O571.434[理学—粒子物理与原子核物理]