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

摘要

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239Pu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239Pu(n,f)裂变驱动势研究,计算了几个典型能量中子诱发239Pu(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239Pu(n,f)反应相关的模拟研究,给出了14 MeV中子诱发239Pu(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239Pu(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(G4ParaFissionModel)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239Pu(n,f)反应裂变产物数据,为快中子诱发239Pu(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-induced239Pu(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 for239Pu(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 of239Pu(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-induced239Pu(n,f) reaction are presented. Average total kinetic energy of the fission-fragment for239Pu(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 G4ParaFissionModel.It is found thatthe 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 G4ParaFissionModel. [Conclusions] The Potential-driving model can well describe the post-fission physical process for239Pu(n,f) reaction. It is a more reliable method for the study on fission-product nuclear data of fast neutron-induced239Pu(n,f) reaction.