Dominant contributors to seismic risk - an appraisal

The purpose of this paper is to assess existing seismic margins in the structures and equipment at a selected number of nuclear power plants for which seismic probabilistic risk assessment (PRAs) exist and to identify dominant contributors to seismic risk. The paper also discusses the causes for the seismic risk dominance of these contributors. Finally, it provides a list of structural and equipment items that should receive particular attention in any seismic margin review. The paper has utilized the quantitative results of the seismic PRAs on Zion, Indian Point Units 2 and 3, Limerick and Millstone Unit 3