Nuclear accident probability approach

Despite its shortcomings, WASH-1400 provides at this time (1978) the most complete single picture of accident probabilities associated with nuclear reactors. The fault tree/event tree approach coupled with an adequate database is the best method available to quantify these probahililies. 

CREAM Cognitive reliability and error analysis method. In CREAM, the operator model is more significant and less simplistic than that of first generation approaches. It can be used both for performance prediction as well as accident analysis. CREAM is used for evaluation of the probability of a human error for completion of a specific task. There is good application of fuzzy logic in this method. It was again started for nuclear application but has wider applications, too. 

Kim Seong, 2006a, Kim Seong, 2006b, BBNs as computational models for situation assessment of nuclear power plant operators. Used to assess probability of mis-diagnosis of plant accidents. Approach inspired by BBN applications as diagnostic/decision aid. SA... 

The Reactor Safety Study was prompted in part by a request from Senator John Pastore for a comprehensive assessment of reactor safety. The AEC s first response to this request was the WASH-1250 report entitled The Reactor Safety Study of Nuclear Power Reactors (Light Water-Cooled) and Related Facilities, which was published in final form in July 1973. However, WASH-1250 did not provide a probabilistic assessment of risk as requested in Senator Pastore s letter. At the time, relevant probabilistic estimates were quite limited in scope and/or highly subjective. For example, in a policy paper dated November 15, 1971, to the commissioners proposing an approach to the preparation of environmental reports, the regulatory staff estimated that the probability of accidents leading to substantial core meltdown was 10 per reactor-year. In retrospect, this was a highly optimistic estimate, but it typifies the degree to which meltdown accidents were considered "not credible."... 

DOE commissioned an independent safety, assessment (ISA) of the electric power systems for the Savannah River production reactors. This report (Reference 1) recommended that a graduated-risk- acteptance approach be used to determine the acceptability of the electric. power sy stem for restart. A. key point in this approach is that at one end of the risk spectrum there needs to be a very strong confidence that the systems can accommodate the postulated transients and accidents that could.occur in. the near. future. At the other end of the risk spectrum, posftulated accidents that are rare (that is extremely low probabilities) do not necessarily have to be resolved completely prior to restart. This approach is consi tent with that used by the NRC when considering the readiness of a licensed nuclear power plant to restart. The general restart criteria below are based upoh this graduated-risk-acceptance approach. 

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