Aerial view of nuclear reactor during 2011 Missouri River flood
All nuclear power plants must consider and evaluate external flooding risks such as flash flooding from rain, river flooding, dam failure, hurricane and tsunami. These events challenge off-site power, threaten many on-site plant mitigation components, challenge the integrity of plant structures and limit plant access. Plants must understand the impact of these events in order to fully comprehend and prepare for these plant risks. Existing plant mitigation procedures may not be adequate to deal with these types of events.
Westinghouse developed external flooding procedural guidance and alternative strategies for the mitigation of reactor coolant system and used fuel pool challenges caused by severe floods. Plants have implemented specific Westinghouse strategies that provide margin during an actual plant challenge, demonstrating that Westinghouse leads the industry in external flooding probabilistic risk assessment (PRA) experience. Westinghouse uses lessons learned from this potentially complex analysis to deliver timely solutions to market and to help its customers meet U.S. Nuclear Regulatory Commission requirements in a cost-effective manner.
Frequency of exceedance for flood elevations
As shown by the Fukushima event and more recently by the flooding along the Mississippi and Missouri rivers in the United States, external flooding risks can pose a very real and significant challenge to plant safety during both power operations and shutdown conditions. Strategies to cope with such events can be developed based upon a full understanding of the risk contributors and associated insights for the event.
Analysis steps to estimate flood exceedance curves