Accident characterization methodology

The Nuclear Regulatory Commission (NRC) is preparing NUREG-1150 to examine the risk from a selected group of nuclear power plants. NUREG-1150 will provide technical bases for comparison of NRC research to industry results and resolution of numerous severe accident issues. In support of NUREG-1150, Sandia National Laboratories has directed the production of Level 3 Probabilistic Risk Assessments (PRAs) for the Surry, Sequoyah, Peach Bottom, and Grand Gulf nuclear power plants. The Accident Sequence Evaluation Program (ASEP) at Sandia has been responsible for the Level 1 portion of the analyses, which includes estimation of core damage frequency and characterization of the dominant sequences. The ASEP analyses are being documented in NUREG/CR-4550. The purpose of this paper is to briefly describe and evaluate the methodology utilized in these analyses. The methodology will soon be published in more detail as Reference 5. The results produced for NUREG/CR-4550 using this methodology are summarized in another paper to be presented at this conference.