基于新型燃料堆芯的不确定性分析研究

Uncertainty Analysis of Novel Fuel Core

参考日本第三代实验堆JRR-3,研究了核数据、输入参数的不确定性对有效增殖因子keff的影响。针对核数据,首先开展了核数据对3维全堆芯keff的不确定性分析及对组件均匀化常数的不确定度计算;其次以组件均匀化常数库为基础,通过抽样方法,采用堆芯计算程序进行了全堆芯模拟,进行了核数据在两步法计算下的影响分析。针对输入参数,首先通过敏感性分析筛选出对keff影响较大的参数,然后使用参数统计法、非参数统计法等多种不确定性分析方法对备选参数进行量化分析。结果表明:核数据对堆芯keff的相对不确定度为0.540 6%,其中235U的平均裂变中子数和瞬发中子裂变份额具有最大的敏感性系数,而235U平均裂变中子数和Al的(n, fission)反应具有最大的不确定性;输入参数的不确定性引起keff的相对不确定度为0.2%,参数统计法与非参数统计法在对keff的容忍区间计算结果上相近。

The effects of uncertainty of nuclear data and input parameters on the effective multiplication factor(k eff)are investigated referring to the Japanese third-generation experimental reactor JRR-3.The uncertainty analysis of the effective multiplication factor of three-dimensional full core and the uncertainty calculation of the component homogenization constant are carried out.Then,based on the component homogenization constant library,a full core simulation is conducted by using a sampling method and a core calculation program,and an impact analysis of nuclear data under two-step calculation is proposed.For the input parameters,sensitivity analysis is used to screen out the parameters that have a significant impact on the effective proliferation factor.Then,various uncertainty analysis methods,such as parameter statistics and non parameter statistics,are used to quantitatively analyze the candidate parameters.The results show that the relative uncertainty of nuclear data on the effective multiplication factor of the core is 0.5406%,where the average number of fission neutrons and the instantaneous neutron fission fraction of 235 U nuclide have the highest sensitivity coefficient,while the average number of fission neutrons of 235 U nuclide and the reaction of Al nuclide have the highest sensitivity coefficient.The relative uncertainty of input parameters for k eff is 0.20%,and the results of parameter statistical method and non parameter statistical method in calculating the tolerance interval for k eff are similar.