The Seismic Fragility Analysis of a Condensate Storage Tank with Age-Related Degradation Considering Realistic Correlations

The age-related degradation of structures and passive components (SPCs) in nuclear power plants (NPPs) is generally not significant, but it can potentially affect the safety of older plants and become an important factor for their long-term operation. A seismic fragility analysis of a condensate storage tank (CST) with age-related degradation was investigated in a previous paper. In reality, however, large uncertainties exist in the degradation phenomena of the CST, and there remains no perfect knowledge in representing them. Nevertheless, there is some degree of assurance in the correlations between the degradation cases. This paper shows a stochastic approach to treat age-related degradations in the seismic fragility analysis of a CST