Development of a Software Tool for Seismic Probabilistic Safety Assessment Quantification with a Sufficiently Large Number of Bins for Enhanced Accuracy

Ji Suk Kim,Man Cheol Kim

doi:10.3390/en14061677

Abstract

Quantification in seismic probabilistic safety assessment (PSA) includes the convolution of hazard and fragility curves. Because it is difficult to find the closed-form integration for the convolution of two curves, numerical methods are widely used in practice. In practical applications, the number of ground motion level bins in numerical methods is limited, and it is not clear whether the limited number of bins leads to conservative or optimistic results. In this study, the effect of the number of bins on the quantification results with simplified assumptions is investigated. It is found that the quantification results mostly decrease as the number of bins increases. To enhance accuracy in the quantification results of seismic PSA, a method and a software tool that enable a sufficiently large number of bins to be used for the quantification of seismic PSA models are developed. The application of the developed software tool to an example seismic PSA model demonstrates how the quantification results approach accurate results as the number of bins increases. The software tool developed in this study is expected to enhance the accuracy of seismic PSA quantification results.

Highlights

A seismic event is an extremely interesting event in the evaluation of the risk of a nuclear power plant
The curve derived from the hazard analysis is generally obtained from available seismic hazard data and ground motion prediction equations and presented as the exceedance frequency of a seismic event depending on the ground motion level, such as peak ground acceleration and spectral acceleration
The software tool enables practical analysis of the seismic risk with a sufficiently large number of bins to enhance the accuracy of the quantification results; it significantly reduces the work involved in manual modeling while preserving the logical links between the primary event tree and secondary event trees

Summary

Introduction

A seismic event is an extremely interesting event in the evaluation of the risk of a nuclear power plant. One of the most important advantages of the approach that uses discrete hazard interval models to estimate the seismic risk is the preservation of the logical links between the primary seismic event tree and secondary event trees.

Effect of Number of Bins on the Quantification Results

Quantification with a Sufficiently Large Number of Bins

Application to an Example Seismic PSA Model

Findings

Conclusions