Seismic Safety Margins Research Program Phase I final report: fragilities development (Project VI). [PWR; BWR]

The Seismic Safety Margins Research Program is an NRC-funded program directed towards estimating the conservatism in the NRC Standard Review Plan seismic safety requirements with the ultimate goal of developing improved requirements. As part of this program, calculations of the seismic risk from a typical commercial nuclear reactor are being made. These calculations require a knowledge of the probability of failure (fragility) of safety-related components in the reactor system which actively participate in the hypothesized accident scenarios. This report describes the development of the required fragility relations and the data sources and data reduction techniques upon which they are based. Both building and component fragilities are covered. The building fragilities are for the Zion Unit 1 reactor which was the specific plant used for development of methodology in the program. Some of the component fragilities are site-specific also, but most have been developed to apply to generic categories of components.