DEVELOPMENT OF RESPONSE-BASED FRAGILITY CURVES FOR SEISMIC PROBABILISTIC RISK ASSESSMENT OF NUCLEAR POWER PLANTS

摘要

Seismic probabilistic risk assessment (SPRA) determines the annual frequency of unacceptable performance of a nuclear power plant (NPP), such as core melt and release of radiation. In conventional SPRA methodologies, fragility curves express the conditional probability of failure of a structure or component for a given ground-motion parameter, such as peak ground acceleration (PGA) or spectral acceleration. However, damage and failure of NPP components are more closely tied to structural response parameters than to ground motion parameters. The use of ground-motion parameters greatly increases the dispersion in the fragility curves. In the new SPRA procedure proposed by Huang et al. (2011a, b), the fragility curves are defined in terms of structural response parameters, such as floor spectral acceleration and peak story drift. The use of structural response parameters in developing component fragility curves reduces the dispersion in the curves and enables the curves to be independent of seismic hazard and closely related to component capacity. In this study, the procedures to develop response-based fragility curves for structural components and equipment are proposed. Response-based fragility curves were developed using the proposed methodology for sample structural components and equipment in a sample NPP in Taiwan. The developed fragility curves were used in a SPRA for a sample NPP presented in the companion paper entitled "Seismic probabilistic risk assessment of nuclear power plants using response-based fragility curves" (Shen et al. 2013).