中子诱发^(238)U裂变产额的统一评价

Unified Evaluation of Neutron Induced^(238)U Fission Yield

采用基于Z_(P)模型的裂变产额统一评价方法,开展中子诱发^(238)U裂变产额评价,通过拟合实验数据获得优化的模型参数,基于获得的模型参数计算入射能量为裂变谱(F)和14 MeV(H)的中子诱发^(238)U裂变的独立产额和累积产额,并建立了ENDF/B-VI格式数据库。该评价方法包含了裂变独立产额、累积产额和衰变数据相互关联的物理机制,可以获得自洽的产额数据,解决了传统评价方法产额不自洽的问题,同时可以获得缺失或者缺乏实验数据的产额。与国际现有产额数据库比较,本工作评价的累积产额与实验数据的符合度χ^(2)=7.1(F)和2.9(H),与ENDF/B-VIII.0裂变产额子库的χ^(2)=8.0(F)和57.3(H)、JEFF-3.3裂变产额子库的χ^(2)=57.0(F)和74.2(H)相比,有较好的改进。

Fission yield data is important for nuclear reactor design and operation,nuclear device design and testing,military control verification,spent fuel reprocessing,and nuclear waste management.It is also the basic data for fission physics research.This paper adopts a unified evaluation method for neutron induced^(238)U fission yield based on the Z_(P)model.The optimized model parameters are obtained by fitting experimental data.Based on the obtained model parameters,the independent and cumulative yields of neutron induced^(238)U fission with incident energies of fission spectrum(F)and 14 MeV(H)are calculated,and an ENDF/B-VI format database is established.The results are consistent since this evaluation method includes the physical mechanism of the relation among the independent yield,cumulative yield and decay data,avoid the problem of yield inconsistency in traditional method.At the same time,it could produce yield where the measurement data are lack or missing.The conformance between cumulative production of this paper and the experimental data withχ^(2)=7.1(F)and 2.9(H),which is a significant improvement compared to theχ^(2)=8.0(F)and 57.3(H)of ENDF/B-VIII.0,and theχ^(2)=57.0(F)and 74.2(H)of JEFF-3.3.