基于评价核数据库的连续点截面处理模块ACEXS的开发与验证

Development and Verification of Continuous Point Section Processing Module ACEXS Based on Evaluated Nuclear Database

摘要: 蒙特卡罗在反应堆物理计算中具有重要作用，而目前反应堆的蒙特卡罗程序，如MCNP、RMC等，都采用连续能量点截面，开发基于评价核数据库的连续能量点截面处理程序对于蒙特卡罗计算具有重要意义。利用倒栈法，自主开发了连续能量点截面处理模块ACEXS。ACEXS的主要功能是把ENDF数据库中的角分布和能量分布数据转化成概率表形式，包括MF4、MF5和MF6中的所有的反应道，这些反应道包括裂变、(n, 2n)、(n, 3n)等。然后基于ENDF/B-VII.1评价核数据库制作了连续能量点截面数据库，对比了ACEXS产生的概率分布与NJOY2016的结果，概率密度最大误差不超过0.5%，累积密度最大不超过0.1%。利用ICSBEP手册中的临界基准题对数据库精度进行了验证，ACEXS与ACER的结果绝对偏差小于100 pcm。最后采用快堆基准题ZPR6/7，计算了基准题有效增殖因子，ACEXS的计算结果与ACER的偏差为6 pcm,由此说明程序开发正确，计算结果与ACER的计算结果吻合较好。

Abstract: Monte Carlo plays an important role in reactor physical calculation, and the current reactor Monte Carlo program, such as MCNP, RMC, etc., all use continuous energy point cross section. It is of great significance to develop continuous energy point cross section processing program based on evaluation nuclear database for Monte Carlo calculation. A continuous energy point cross section processing module, ACEXS, is developed by using backward stack method. The main function of ACEXS is to convert the angular distribution and energy distribution data in ENDF database into probability table form, including all reaction paths in MF4, MF5 and MF6, including fission, (n, 2n), (n, 3n), etc. Then, based on ENDF/B-VII.1 evaluation kernel database, the continuous energy point cross section database was made, and the probability distribution generated by ACEXS was compared with the results of NJOY2016. The maximum error of probability density was less than 0.5%, and the maximum cumulative density was less than 0.1%. The accuracy of the database was verified by the critical benchmark in ICSBEP manual, and the absolute deviation between ACEXS and ACER was less than 100 pcm. Finally, fast reactor benchmark ZPR6/7 was used to calculate the effective proliferation factor of the benchmark. The deviation between ACEXS and ACER was 6 pcm, indicating that the program was developed correctly and the calculated results were in good agreement with those of ACER.