Seismic fragility analysis of the transfer and purging chamber in a nuclear power plant based on incremental dynamic analysis

The seismic fragility of the transfer and purging chamber in a nuclear power plant is assessed in this paper based on the incremental dynamic analysis method. Select the peak ground acceleration as the ground motion intensity measure, and select the compressive strain of concrete, steel plate stress, and peak displacement of the structure as the damage measures. This paper calculates the dynamic response of the transfer and purging chamber under 160 seismic conditions and analyzes the conditional failure probabilities of no damage, slight damage, recoverable damage, and serious damage. The result shows that the conditional failure probabilities of concrete and steel plate have remarkable differences under the design basis ground motions, and both are lower than the criterion restriction. The conditional failure probability of peak displacement of the cantilever in the transfer and purging chamber under the design basis ground motions exceeds the criterion restriction. It indicates that peak displacement of the cantilever is overlarge in one direction caused by insufficient constraints and too small local stiffness. The failure probability of the transfer and purging chamber that does not meet operational basis performance demand is 6.32 × 10−2‱, and the failure probability of the transfer and purging chamber that does not meet safety shutdown performance demand is 1.76 × 10−3‱.