基于Potential-driving模型的中子诱发^(239)Pu裂变产物计算与模拟研究

Calculation and simulation on the fission products for neutron-induced ^(239)Pu fission based on Potential-driving model

当前新型核能利用系统及核数据评价的发展对快中子诱发^(239)Pu裂变核数据提出了更高的精度需求。本工作基于已提出并构建的Potential-driving模型,通过中子诱发^(239)Pu(n,f)裂变驱动势研究,计算了几个典型能量中子诱发^(239)Pu(n,f)反应发射中子前裂变碎片质量分布,并与实验数据进行了对比。结果显示:Potential-driving模型计算数据能够很好地与实验数据符合。将Potential-driving模型植入GEANT4程序,开展了快中子诱发^(239)Pu(n,f)反应相关的模拟研究,给出了14 Me V中子诱发^(239)Pu(n,f)反应的裂变碎片独立产额质量分布和电荷分布、累积产额质量分布和电荷分布、动能分布、裂变中子能谱以及^(239)Pu(n,f)反应裂变碎片平均总动能随入射中子能量的变化等数据,并与GEANT4程序原有的参数化裂变模型(G4Para Fission Model)模拟结果、ENDF/B-VII.1库评价数据以及实验数据进行了比较。结果显示:所发展的Potential-driving模型能很好地预测快中子诱发^(239)Pu(n,f)反应裂变产物数据,为快中子诱发^(239)Pu(n,f)反应裂变产物核数据的研究提供了一种更可靠的计算方法。

[Background] At present, high-precision fission nuclear data of fast neutron-induced ^239Pu（n,f） reaction is required for the study of new-generation nuclear systems. [Purpose] Based on the proposed Potential-driving model in the earlier study, the calculation and simulation methods are developed to predict the fission product data for ^239Pu（n,f） reaction in this paper. [Methods] The driving potential distribution and pre-neutron-emission mass distribution for ^239Pu（n,f） reaction are calculated based on the Potential-driving model. In addition, the Potential-driving model is implanted in the GEANT4 code for simulating the physical process of ^239Pu（n,f） reaction. The mass distribution and the charge distribution of independent and cumulative yield, the fission-fragment kinetic energy distribution and the fission neutron spectrum of post-neutron-emission for D-T neutron-induced ^239Pu（n,f） reaction are presented. Average total kinetic energy of the fission-fragment for ^239Pu（n,f） reaction as a function of the incident neutron energy is also shown. [Results] The calculated and simulated results in the Potential-driving model are compared with the experimental data, the evaluated data from ENDF/B-VII.1 and the simulated data based on the G4 Para Fission Model. It is found that the results calculated by the Potential-driving model are in good agreement with the experimental data and the ENDF/B-Ⅶ.1 evaluated data, are better than those data calculated by the G4 Para Fission Model. [Conclusions] The Potential-driving model can well describe the post-fission physical process for ^239Pu（n,f） reaction. It is a more reliable method for the study on fission-product nuclear data of fast neutron-induced ^239Pu（n,f） reaction.