非参数统计方法在DNBR限值计算中的应用

Application of nonparametric statistic method for DNBR limit calculation

非参数统计方法是一种不依赖某种特定分布的统计推断方法,它通过抽样计算得到总体在一定概率水平和置信度下的容许限。DNBR裕量是核电站设计中的重要参数,能够反映核电站的安全水平。本文应用基于Wilks公式容许限的非参数统计方法及VIPRE-01程序计算300MW核电厂在全失流事故(LOFA)下的DNBR设计限值,并与ITDP方法得到的DNBR限值相比较,以期获得一定的DNBR裕量。结果表明,相对于ITDP方法,非参数统计方法获得了2.96%的DNBR裕量,该方法由于减少了分析过程中的保守性,能够提供更大的DNBR裕量,而DNBR裕量增加有利于堆芯换料方案的改进。

Background： Nonparametric statistical method is a kind of statistical inference method not depending on a certain distribution; it calculates the tolerance limits under certain probability level and confidence through sampling methods. The DNBR margin is one important parameter of NPP design, which presents the safety level of NPP. Purpose ＆ Methods： This paper uses nonparametric statistical method basing on Wilks formula and VIPER-01 subcharmel analysis code to calculate the DNBR design limits （DL） of 300MW NPP （Nuclear Power Plant） during the complete loss of flow accident, simultaneously compared with the DL of DNBR through means of ITDP to get certain DNBR margin. Results： The results indicate that this method can gain 2.96% DNBR margin more than that obtained by ITDP methodology. Conclusions： Because of the reduction of the conservation during analysis process, the nonparametric statistical method can provide greater DNBR margin and the increase of DNBR margin is benefited for the upgrading of core refuel scheme.