ScholarWorks@중앙대학교

초록

Human actions play a crucial role in accident mitigation strategies at nuclear power plants. Thus, human failure events are key elements in probabilistic risk assessment model. Human reliability analysis is used to identify human failure events and quantify human error probabilities. Among human failure events, there is a failure mode that arises from delayed operator actions. In this failure mode, time is a critical factor in determining human error probabilities. In practice, time is influenced by several factors such as accident scenarios and plant conditions which are referred to as performance shaping factors. Due to the randomness of time, it is treated as a random variable and the performance shaping factors are modeled to affect parameters of the random variable. Additionally, in many nuclear power plant accident scenarios, sequential human actions are necessary for mitigation. In this case, human error probability depends on total time required for these actions. On the other hand, performance shaping factors may vary according to conditions and it can be uncertain. This uncertainty should be integrated into total time required and the following human error probabilities. In this context, although each time required is separately analyzed and treated as independent random variable, these times are interdependent due to shared and uncertain performance shaping factors. This paper proposes a quantification method for the dependency arising from performance shaping factors and analyzes its impacts on human error probabilities.

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