Influence of frequency content of ground motions on seismic fragility of equipment in nuclear power plant

Abstract

The objective of this study is to investigate the influence of frequency content of ground motions on the seismic fragility of nuclear power plant (NPP) equipment. Transfer functions of a steam generator, a reactor vessel and an auxiliary building of a Korean APR1400 type NPP are extracted from finite element models. The transfer functions are used to investigate the influence of frequency contents of input ground motion on the seismic fragilities of the equipment. A methodology is proposed to transform fragility functions that are defined in terms of peak ground acceleration (PGA) of the design response spectrum to those that are defined in terms of realistic response parameters. The method is applied to a three-dimensional finite element model of the auxiliary building as a case study. The results show that all equipment has a higher probability of failure when the auxiliary building is subjected to ground motions with high-frequency content.