Sensitivity analysis based on Morris method of passive system performance under ocean conditions

Abstract

Passive safety systems, which do not require external input to operate, are widely used to enhance the inherent safety in new generation nuclear power plants. A challenging issue still to be resolved is the quantification of the functional failure probability of passive safety systems. The evaluation of functional failure relies on repeated thermal-hydraulics simulations which is usually time-consuming in practice. Response surface method has been proposed to tackle this issue. However, the number of input parameter limits its efficiency to a great extent. Therefore, it is necessary to identify the uncertain input parameters that have an important impact on the system performance, which helps reduce the dimension of the input parameters. Especially in marine nuclear power plants, the complex ocean motions will introduce more uncertainties in the passive system behavior. It’s of great significance to screen key parameters for passive safety systems under ocean conditions. In this paper, the Morris method is used to perform an efficient sensitivity analysis to identify key parameters for a passive residual heat removal system in IPWR200. Twenty-four parameters related to passive system behavior are screened and ranked for their sensitivity. The results demonstrated that four of the twenty-four parameters have a more significant influence on the passive system performance.