Abstract The best estimate plus uncertainty (BEPU) methodology is developed to carry out realistic safety analysis of the nuclear power plant. However, the sensitivity analysis in the conventional methodologies often leads to inaccurate results when lacking of the phenomenon identification and ranking table (PIRT) or adopting the local sensitivity analysis methods. As the initial inputs determined in short of the PIRT may neglect some important parameters or identify some unimportant parameters, and the local methods are not appropriate for complex and non-linear systems. In this study, an optimized moment-independent global sensitivity analysis method with very low computational cost was utilized to improve the sensitivity analysis framework of the BEPU methodology. The reliability as well as the applicability of the method were assessed through some tests and a large break loss of coolant accident (LBLOCA) of the LOFT facility. The improved sensitivity analysis framework was then applied to the BEPU analysis of a typical three-loop pressurized water reactor CPR1000, and the reliability of the optimized moment-independent method was further confirmed by comparing the sensitivity analysis result of the method to the results of the BEMUSE project and the Spearman method. Besides, two new parameters were identified to have great influence on the PCT, and the two parameters should be taken into consideration in the uncertainty analysis of the BEPU methodology.

中文翻译：

---

最佳估计加不确定性灵敏度分析优化及在三回路压水堆大断口失水事故中的应用

摘要 最佳估计加不确定性（BEPU）方法被开发用于对核电厂进行现实的安全分析。然而，传统方法中的敏感性分析在缺乏现象识别和排序表（PIRT）或采用局部敏感性分析方法时，往往会导致结果不准确。由于缺乏PIRT确定的初始输入可能会忽略一些重要参数或识别一些不重要的参数，并且局部方法不适用于复杂和非线性系统。在本研究中，利用优化的具有极低计算成本的与矩无关的全局灵敏度分析方法来改进 BEPU 方法的灵敏度分析框架。该方法的可靠性和适用性是通过一些测试和 LOFT 设施的冷却剂大断裂损失事故 (LBLOCA) 来评估的。将改进后的灵敏度分析框架应用于典型的三回路压水堆CPR1000的BEPU分析，通过将方法的灵敏度分析结果与该方法的灵敏度分析结果进行比较，进一步证实了优化的矩无关方法的可靠性。 BEMUSE 项目和 Spearman 方法。此外，确定了两个对 PCT 有很大影响的新参数，在 BEPU 方法的不确定性分析中应考虑这两个参数。将改进后的灵敏度分析框架应用于典型的三回路压水堆CPR1000的BEPU分析，通过将方法的灵敏度分析结果与该方法的灵敏度分析结果进行比较，进一步证实了优化的矩无关方法的可靠性。 BEMUSE 项目和 Spearman 方法。此外，确定了两个对 PCT 有很大影响的新参数，在 BEPU 方法的不确定性分析中应考虑这两个参数。将改进后的灵敏度分析框架应用于典型的三回路压水堆CPR1000的BEPU分析，通过将方法的灵敏度分析结果与该方法的灵敏度分析结果进行比较，进一步证实了优化的矩无关方法的可靠性。 BEMUSE 项目和 Spearman 方法。此外，确定了两个对 PCT 有很大影响的新参数，在 BEPU 方法的不确定性分析中应考虑这两个参数。