247 Current Limitations of Fire PRA Methodology and Potential Areas for Future Research Activities (PSAM-0352) Available to Purchase

The U.S. Nuclear Regulatory Commission's (NRC's) Office of Nuclear Regulatory Research (RES) and the Electric Power Research Institute (EPRI) have recently issued a joint publication documenting consensus procedures for a state-of-the-art nuclear power plant (NPP) Fire Probabilistic Risk Assessment (FPRA). This consensus methodology has resolved many past fire PRA weaknesses, including those issues identified by the NRC, based on the Individual Plant Examination for External Events (IPEEE) process. The study also identified a number of remaining analytical challenges that were not fully addressed by the new methodology. This paper will discuss these identified analytical challenges where additional research may be beneficial.

The primary object of the Fire Risk Requantification Study (FRRS) was to consolidate existing methods including the incorporation of previous research results. In practice, several of the new methodological approaches represent advances that go well beyond mere consolidation. However, in the end, some areas were identified whose resolution required efforts beyond the scope of the FRRS. In addition, some remaining challenges are associated with methods advances going beyond current state-of-the-art limitations. Further advancements in these challenge areas would be beneficial to the fidelity, usefulness, and/or accuracy of FPRA results.

Specific analytical challenge areas discussed in this paper are (1) manual fire fighting analysis, (2) analysis of fire-induced spurious equipment operations, (3) event data reporting and analysis, (4) post-fire human reliability analysis (HRA), (5) treatment of administrative aspects of the fire protection program, (6) multiple concurrent fires and multiple concurrent initiating events, (7) general reliability/unavailability factors for fire protection systems and fire barriers, (8) pre-initiator human failure events (HFEs), and (9) the impact of smoke on plant equipment. The discussion will include both a technical description of the remaining challenges and an assessment of the potential benefit to FPRA of further improvements. To the extent possible, potential approaches to address each challenge area are discussed also.