Seismic Probabilistic Risk Assessment of Nuclear Power Plants Using Response-Based Fragility Curves

Abstract

Seismic probabilistic risk assessment (SPRA) has been widely used to compute the frequencies of core damage and release of radiation of a nuclear power plant (NPP). In 2011, Huang et al. (2011a, 2011b) published a SPRA methodology with the following characteristics different from the widely used Zion method: (a) seismic fragility curves are defined as a function of structural response parameters, such as floor spectral acceleration and story drift; (b) nonlinear response-history analysis is used to estimate statistical distributions of seismic demands for structural and non-structural components of NPPs; (c) Monte Carlo simulation is used to determine damage states of structural and non-structural components. In the study presented in this paper, the seismic risk of a sample NPP was evaluated using the methodology of Huang et al. (2011a, 2011b). The seismic risk was quantified using the annual frequency of unacceptable performance defined by a sample accident sequence for a sample NPP. The values of seismic risk computed using the methodology of Huang et al. (2011a, 2011b) and Boolean Algebra were compared to evaluate the accuracy and efficiency of the methodology of Huang et al. (2011a, 2011b). The two procedures generate similar risk values and the methodology of Huang et al. (2011a, 2011b) is more efficient than the procedure using Boolean Algebra.