Analysis of the LaSalle Unit 2 Nuclear Power Plant: Risk Methods Integration and Evaluation Program (RMIEP)

Abstract

This report is a description of the internal fire analysis performed on the LaSalle County Nuclear Generating Station, Unit II. Insights gained from the NUREG-1150 fire analyses of Peach Bottom and Surry were used to the greatest extent possible in this risk assessment. As part of this effort, a new data base for fires was constructed (NUREG/CR-4586). This data base aided in quantification of initiating event frequencies. The most detailed integration with internal events analysis to date in fire risk assessment was also accomplished. The same system fault trees used for internal events were utilized in the fire analysis, which included modeling of components down to the contact pair level. Subsidiary equations were created to map the effects of cable failures and spurious actuations. For all components modeled in the internal event fault trees, associated cables were identified and component and cable locations were traced and mapped into the fault trees. A detailed screening analysis was performed which showed most plant areas had a negligible contribution to fire-induced core damage frequency. A detailed analysis of the fire risk resulted in a total (mean) core damage frequency of 3.21E-5 per year.