Seismic risk at the Zion nuclear power plant

This paper presents the results of a seismic risk analysis of the Zion nuclear power plant. It also shows the effects of assumptions about plant configuration, plant operation, and dependence. This analysis is part of the Seismic Safety Margins Research Program (SSMRP), a program funded by the US Nuclear Regulatory Commission. The SSMRP has developed methods and computer codes for estimating the probability of an earthquake induced radioactive release from a plant. The risk analysis begins with estimation of the seismic hazard function and a set of earthquake time histories. A dynamic structural response code computes local responses based on the earthquake time histories for many locations in the plant. (Finite element models are used in the response computations). Then, the peak responses are combined with fragility functions and fault and event trees in computing the probability of earthquake and radioactive release. (Fragility functions describe the strengths of many types of components. Fault and event trees describe radioactive release in terms of component failures). Finally, the resulting risk in man-REMs per year is estimated