最佳估算加不确定性分析方法在我国核安全审评中的应用

摘要

The methods that used in most conventional computer codes are conservative, which will lead to unnecessary excessive margins and more difficulty for nuclear power plants design and improvement.Using best-estimate plus uncertainty analysis method may reduce or eliminate these unnecessary limits.In the review process of AP1000 and CAP1400, National Nuclear Safety Agency has used the best-estimate method for large-break LOCA accident.In this paper the four best-estimate plus uncertainty analysis methods are introduced, the source of uncertainty and uncertainty statistic methods are described.Then the independent audit calculation of AP1000 NPP large-break LOCA accident is carried out with RELAP5 code based on ASTRUM method.Through calculations of 59 groups of samples, the maximum PCT is 1 070℃, and it can meet the acceptance criteria.%目前核电厂安全分析用计算机程序多是基于保守方法开发的,给核电厂的设计和分析带来了过量裕度,增加了核电厂优化和改进的难度,使用最佳估算加不确定性分析方法可以减少或消除这些不必要的限制.在AP1000和CAP1400的审评过程中,国家核安全局采用最佳估算加不确定性方法对大破口失水事故进行了审查.本文介绍了四种最佳估算加不确定性分析方法,对不确定性的来源和不确定性统计方法进行了论述.基于ASTRUM方法,利用RELAP5程序对AP1000核电厂大破口失水事故进行了独立审核计算,经59组抽样计算后,最大的燃料包壳温度值为1070℃,满足验收准则要求.