最佳估算方法在核临界安全分析的应用研究

最佳估算方法可以同时对多个参数按概率分布进行抽样,从而模拟系统真实的物理状况,计算结果的容忍区间及置信水平与抽样数目有关。本文将最佳估算方法应用于压水堆核电站乏燃料贮存格架和燃料运输容器的临界安全分析,采用非参数抽样统计方法,多参数同时抽样,并对各抽样参数的敏感度进行分析。抽样计算的结果统计分析表明,最佳估算方法更接近真实值,证明原逐参数单独进行敏感性分析方法的保守性并得到相应的保守裕量;对于特定研究对象参数的敏感性排序是稳定的,主要取决于参数自身的敏感性,参数的范围及分布的影响较小,应在相关设备的设计与制造中重点关注敏感度高的参数。

Study on Best Estimate Method Applied to Nuclear Criticality Safety Analysis

In Best Estimate method,multiple parameters are randomly sampled at the same time according to their probability distribution. Best Estimate method aims at simulating true condition and the number of code runs is related to the tolerance percentile and confidence level. Best Estimate method is applied to the criticality analysis of spent fuel rack and fuel transport package,using nonparametric sampling approach which means that multiple parameters are sampled at the same time. The sorted sequence of parameter sensitivity is got from parameter sensitivity analysis. The statistical analysis of calculation results demonstrates that the result of Best Estimate method is closer to true-value and the method of analyzing every single parameter sensitivity is conservative. The sequence of parameter sensitivity is stable when analyzing specific condition,which mostly depends on parameter's own sensitivity. The range and distribution of parameter have little effect on the sequence. The sensitive parameters should be paid close attention to in the design and manufacturing process of relevant equipment.