Risk Methods Insights Gained from Fire Incidents (NUREG/CR-6738, SAND2001-1676P)

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Publication Information

Manuscript Completed: August 2001
Date Published: September 2001

Prepared by:
S.P. Nowlen, Sandia National Laboratories
Dr. M. Kazarians, Kazarians and Associates
F. Wyant, Sandia National Laboratories

Sandia National Laboratories
Albuquerque, New Mexico 87185-0748
Operated by Sandia Corporation

Kazarians and Associates
Glendale , California 91205

H.W. Woods, NRC Project Manager

Prepared for:
Division of Risk Analysis and Applications
Office of Nuclear Regulatory Research
U.S. Nuclear Regulatory Commission
Washington, DC 20555-0001

NRC Job Code Y6037

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This report presents the findings of an effort to gain new fire probabilistic risk assessment (PRA) methodology insights from fire incidents in nuclear power plants. The study is based on the review of a specific set of 25 fire incidents including fires at both U.S. and foreign reactors. The sequence of actions and events observed in each fire incident is reconstructed based on the available information. This chain of events is then examined and compared to typical assumptions and practices of fire PRA. The review focuses on two types of actions and events. First are events that illustrate interesting insights regarding factors that fall within the scope of current fire PRA methods. Second are events observed in actual fire incidents that fall outside the scope of current fire PRA methods. Fire PRA insights are then drawn based on these observations. The review concludes that the overall structure of a typical fire PRA can appropriately capture the dominant factors involved in a fire incident. However, several areas of potential methodological improvement are identified. A few factors are also identified that fall outside the scope of current fire PRAs including the occurrence of multiple initial fires or secondary fires, multiple simultaneous initiating events, and some aspects of the smoke control and human response assessment.

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