ABSTRACT
Major part of the nuclear power sites house more than one reactor unit and other nuclear facilities such as spent fuel pool storage. Currently, multi-unit risks have not typically been adequately accounted for in risk assessments, since the licensing is based on unit-specific PSA with focus on a reactor accident. This paper presents an approach to site risk analysis, taking into account various dependences between the units. The dependences can be caused by external hazards, which can affect multiple units at the same time; shared operational and safety systems at the site; common staff who should manage the situations. The site risk assessment approach has been developed with aid of two pilot studies made for two Swedish sites. Preliminary results from the pilot studies are presented in the paper.
