裂变产额是确定核工程宏观物理量（如裂变燃耗等）的重要基本参数。然而在核工程测试现场，用户采用的产额曲线与实验室给出的曲线不同，从而引发了长期的争议。经多方面的分析研究，认为一个可能的原因是现场与实验室的条件不同，即现场中存在短时间（~us）强中子场（10^30-10^31中子/秒，比实验室高16-17个数量级）。该强中子场与裂变产物继续发生剧烈的产生和消耗反应，导致裂变产额能量曲线与实验室结果的差异。本项目拟建立相应的核反应网络方程计算系统，模拟强中子场中裂变产物核的中子反应及衰变等复杂的核过程，计算产物核丰度在不同中子场(强度、谱形)下随时间的变化规律，研究中子场对产物的质量分布及缓发γ的影响规律，为解决上述争议提供参考依据。此研究不仅可为核工程测试、核查、剂量防护等应用提供数据基础，对研究了解裂变碎片性质、发展裂变后期理论也有相应的科学意义。

The fission product yield is a basic parameter for determining the macroscopic physical quantities, like burn-up etc. However, the data used by the users at site are different from the ones measured and evaluated in the laboratories, which lead to a long standing dispute. By the multi-analysis research, it is recognized that a possible reason is the different conditions at site from the laboratory, namely at site there is an intense neutron field (10^30-10^31 neutron /s.cm2, 16-17 order of magnitude higher than that in laboratory) in short time (~μs). The product nuclides are created and eliminated through numerous of neutron reactions, which lead to the difference of the fission product yield from the laboratory without or with weak neutron field. In this project, a program, as well as the related nuclear database, will be created to simulate the nuclear processes (neutron reactions and decays) occurred in the intense neutron field. The dependence of the fission product nuclide abundances on the field strength and energy spectrum vs. time will be calculated and analyzed. The affect of the intense neutron field on the mass distribution of fission product and the decay γ will be studied. The research of the project can find a possible reason of the discrepancy mentioned above. The research not only can provide the data basis for engineering test、nuclear inspection, radiation protection etc, also has important academic significance for exploring the nature of fission fragment and developing post-fission theory.