Dissertation/Thesis Abstract

Mitigating Consequences of Flooding in a Typical Boiling Water Reactor Similar to Fukushima Daiichi Plant in Japan
by Salehi, Kombiz, Ph.D., The University of North Carolina at Charlotte, 2018, 265; 10830545
Abstract (Summary)

The Fukushima Daiichi nuclear power plant experienced a major accident on March 11, 2011, which was caused by a seismic event of 9.0 magnitude on the Richter scale followed by a tsunami wave of about 15 meters. This combination resulted in the loss of all emergency core cooling systems, including the essential diesel generators and the station batteries. The consequence of such an event was an “accident;” that resulted in multiple degraded core conditions, including hydrogen detonation causing the breach of three containments.

There is a need for a clear approach with careful attention to detail to conduct research on how to mitigate the consequences of an accident similar to the Fukushima Daiichi Nuclear Power Plant for the U.S. nuclear power plants at the coastal states. This research identified the causal factors related to flooding during the 2011 Fukushima Daiichi accident, and evaluated how the damaging consequences of such an event could be significantly reduced for a typical boiling water reactor. To achieve this purpose, the research addressed the impact of flooding that was a major cause of the Fukushima Daiichi nuclear power plant accident.

By using an analytical approach that is common in the nuclear power industry, Probabilistic Risk Assessment, the research identified safety-related systems and key components of such systems that have the potential for failure during a flooding event. The impact of the failure of key components was examined, and how such failures could affect core damage was investigated. This research determined that a single component failure will not result in an increase in core damage. However, the research identified that if there is a loss of all AC and DC power for longer than a day, core damage may occur, even for the U.S. nuclear power plants.

The research made recommendations for both newer and older existing nuclear power plants, especially at coastal sites where Fukushima-type events, but not with the same intensity, are more likely to occur. Implementing one or more of these recommendations will significantly reduce the likelihood of a degraded core condition, even in the presence of seismic events and floodings. This research used an analytical approach to identify what went wrong at Fukushima (causes), and specify what can be done to mitigate damaging consequences (recommendations).

An essential validation of the effectiveness of the recommendations was achieved by performing a repeat analysis after implementing one or more recommendations. When the results of the analyses exhibited a larger margin in the values of core damage frequency, the verification process was completed; that is, implementing a recommendation would reduce the probability of a core damage. This process may be continued beyond the current research and into research on other systems and components after implementing more recommendations.

Indexing (document details)
Advisor: Wu, Jy, Salami, Zia
Commitee: Chan, Shen En, Diemer, John, Salami, Zia, Wu, Jy, Young, David
School: The University of North Carolina at Charlotte
Department: Infrastructure & Environmental Systems
School Location: United States -- North Carolina
Source: DAI-A 80/04(E), Dissertation Abstracts International
Subjects: Management, Environmental management, Energy
Keywords: BWR, Flooding, Fukushima Daiichi accident, Nuclear engineering, TEPCO
Publication Number: 10830545
ISBN: 9780438701724
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