Study on Seismic Fragility Probability Model of Nuclear Power Plant Considering Epistemic Uncertainty

Seismic fragility model formulae considering epistemic uncertainty, which include fragility formula including confidence and mean fragility formula, were the theoretical foundation of seismic fragility analysis for nuclear power plants. In this paper, two types of formulae derivation were conducted, the parameters relationship of fragility formulae was analyzed, and the relationship of HCLPF values calculated by two types of fragility formulae was discussed. The results show that the formulae derivation type based on uncertainty of fragilities enriches the connotation of the fragility formula including confidence. For fragility model formula including confidence, the relationship between the confidence and probability of failure follows a type of distribution, while two types of uncertainties have different influences on probability of failure. When logarithmic standard deviations for two types of uncertainties approach each other, two types of HCLPF values are approximately the same.