Abstract Uncertainties for predictions of thermal hydraulic problem are caused by the complex physical origin. Uncertainty qualification methods are designed to meet the requirement of regulation to ensure acceptable safety margins with enough confidence. Various methods are proposed for the industrial applications to achieve the proposed level of probability and confidence. However, it is not enough to obtain more statistics information with limited calculation by the full evaluation model. The present paper is based on a simplified model of large break loss of coolant accident for peak clad temperature (PCT) estimation (Catton et al. (1990)). The simplified model is based on physical foundation with sufficient uncertainty parameters and trend indication. The higher PCT during blow down phase and reflooding phase was set to be the target output parameter. The numerous parameters and distribution in the simplified model were set to the source of input uncertainty. The effects of PIRT, sample number, uncertainty distribution were studied. The results provided qualitative and quantitative results for uncertainty methods and would be beneficial for the determination of uncertainty qualification methods in engineering design.

中文翻译：

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基于简化LB LOCA模型的PCT估算不确定度定性方法初探

摘要 热力水力问题预测的不确定性是由复杂的物理成因造成的。不确定性鉴定方法旨在满足法规要求，以确保具有足够置信度的可接受的安全裕度。为工业应用提出了各种方法来实现建议的概率和置信水平。但是，通过全评价模型以有限的计算获得更多的统计信息是不够的。本论文基于用于峰值包层温度 (PCT) 估计的冷却剂大断裂事故的简化模型 (Catton 等人 (1990))。简化模型基于具有足够不确定性参数和趋势指示的物理基础。排污阶段和回灌阶段较高的 PCT 被设置为目标输出参数。简化模型中的众多参数和分布被设置为输入不确定性的来源。研究了PIRT、样本数量、不确定度分布的影响。该结果为不确定度方法提供了定性和定量结果，将有利于工程设计中不确定度鉴定方法的确定。