Seismic IPEEE Results and Their Use in Risk-Informed Applications

摘要

The NRC has recently indicated “Risk-Informed” assessments should be used as the technical basis for futuredecisions. Accordingly, the NRC is currently changing 10CFR50 and other regulations to introduce the use of risk-informed,performance-based (RI/PB) criteria. Their objective is to focus resources on those areas which are most significant to plantrisk and to maintain a comparable level of safety performance as compared to the current licensing basis. Risk InformedRegulations are intended to increase regulatory flexibility while maintaining safety performance, and allow utilities to moreeffectively and efficiently utilize their resources. In general, the nuclear industry fully supports the NRC RI/PB initiatives.These risk-informed criteria require inclusion of all internal and external event risks, including seismic. Three majorconsiderations in this regard will be internal events, seismic and fire. Internal and fire events have industry programs toaddress the “risk-informed” process, while seismic currently does not. The seismic portion of the Individual Plant Evaluationfor External Events (IPEEE) is a major building block for the development of seismic risk-informed methods since theindustry has already spent considerable resources towards characterizing plant seismic risk via either a seismic margin studyor a seismic PRA.