EPRI/NRC-RES Fire Human Reliability Analysis Guidelines – Final Report (NUREG-1921)
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Manuscript Completed: May 2012
Date Published: July 2012
Electric Power Research Institute (EPRI)
3412 Hillview Avenue
Palo Alto, CA 94303
EPRI Project Manager: S. Lewis
U.S. NRC-RES Project Manager: S. Cooper
Office of Nuclear Regulatory Research
U.S. Nuclear Regulatory Commission
Washington, D.C. 20555-0001
During the 1990s, the Electric Power Research Institute (EPRI) developed methods for fire risk analysis to support its utility members in the preparation of responses to Generic Letter 88-20, Supplement 4, Individual Plant Examination of External Events (IPEEE). This effort produced a fire risk assessment methodology for operations at power plants that was used by the majority of U.S. nuclear power plants (NPPs) in support of the IPEEE program and by several NPPs overseas. Although these methods were acceptable for accomplishing the objectives of the IPEEE, EPRI and the U.S. Nuclear Regulatory Commission (NRC) recognized that the methods needed to be improved to support current requirements for risk-informed, performance-based (RI/PB) applications.
In 2001, EPRI and the NRC’s Office of Nuclear Regulatory Research (NRC-RES), operating under a Memorandum of Understanding (MOU), embarked on a cooperative project to improve the state of the art in fire risk assessment to support a new risk-informed environment in fire protection. This project produced a consensus document, NUREG/CR-6850 (EPRI report 1011989)—Fire PRA Methodology for Nuclear Power Facilities—which addressed fire risk for at-power operations. NUREG/CR-6850 developed high-level guidance on the process for identifying human failure events (HFEs) and for including them in the fire PRA. The guidance also defined a process for assigning quantitative screening values to these HFEs. It outlined the initial considerations of performance shaping factors (PSFs) and related fire effects that may need to be addressed in developing best-estimate human error probabilities (HEPs). NUREG/CR-6850 did not, however, describe a method to develop best-estimate HEPs reflecting the PSFs and the fire-related effects.
In 2007, EPRI and NRC-RES (again working under the MOU) initiated another cooperative project related to fire PRA to develop explicit guidance for estimating HEPs for HFEs under fire conditions, building on existing human reliability analysis (HRA) methods. This report provides a method and associated guidance for conducting a fire HRA. The process includes the identification and definition of fire HFEs, qualitative analysis, quantification, recovery analysis, dependency analysis, and the treatment of uncertainty. The report also provides three approaches to quantification: screening, scoping, and detailed HRA. Screening is based on the guidance in NUREG/CR-6850, with some additional guidance for scenarios with long time windows. Scoping is a new approach to quantification developed specifically to support the iterative nature of fire PRA quantification. Scoping is intended to provide less conservative HEPs than screening but requires less time and effort than a detailed HRA analysis. For detailed HRA quantification, guidance has been developed on how to apply existing methods to assess fire HEPs.