ABSTRACT
Recently, methods and data for application within Fire PSA according to the state-ofthe-art have been further enhanced and updated. The activities on Fire PSA methods for Nuclear Power Plants (NPP) mainly include the extension of the approaches used for screening as well as for detailed in-depth analysis to all plant operational states during the entire operational life of a NPP including the long-lasting post-commercial shutdown phase until the fuel has been removed from the core and the spent fuel pool. In this context, the goal of Level l Fire PSA was additionally extended from core damage to fuel damage. Major enhancements have been made with respect to determining compartment as well as component specific fire occurrence frequencies by means of a generic approach and consideration of mainly knowledge based response activities to the fire by means of an approach using dynamic PSA methods based on simulations of the scenarios with a three-dimensional computational fluid dynamics code. Regarding the data needed for Fire PSA the update concerns three different aspects. Due to the lack of plant specific data from German NPP generic fire occurrence frequencies are needed as additional input data. Another aspect concerns data on the technical reliability of active fire protection features. The existing corresponding German database has been widely extended and enhanced determining not only failure rate and unavailability per demand for the individual components but also providing fault trees for the whole system, as e.g. the fire detection system. This has been done plant specifically and generically for six NPP units covering in total more than 120 reactor years. Last not least, data on cables as fire loads are being updated with respect to the characteristics and potential cable failure modes and effects on circuits by means of cable failure mode and effect analysis.
