The damage-based fragility analysis and probabilistic safety assessment of containment under internal pressure

A new approach applicable to the probabilistic safety assessment of the prestressed concrete containment vessel (PCCV) under internal pressure is proposed. The proposed procedure uses (a) continuous damage state of the PCCV to characterize the varied damage extent under internal pressure, and (b) damage-based fragility to represent the safety performance of the PCCV. The damage-based fragility is more closely related to component performance than the conventional pressure-based fragility. The use of the continuous damage state of the PCCV enables the different performances of leakage to be considered. The results show that the suggested damage ratios can be used to determine the impact of material uncertainties on the damage behaviors of containment components. The conventional pressure-based fragility analysis method may significantly underestimate the dispersion of the conditional failure probability in comparison with the damage-based fragility method. Based on the estimated fragility results at different confidence levels, the cumulative conditional failure probability (CCFP) of the containment components is obtained by using conventional and proposed probabilistic safety assessment (PSA) methods. It is possible to deduce that the developed damage-based PSA method should be adopted to calculate the CCFP as it provides a more realistic and conservative CCFP of the containment.