Evaluation Method of Response Reliability During an Accident and its Applicability to Fast Reactor Plants

In this study, we develop new indices that evaluate the response capability — response margin and response reliability — of a nuclear power plant in case of occurrence of a severe accident by considering the ability of the nuclear power plant to recover system safety functions, which may have been affected by the accident, to the minimum safety values. Further, we demonstrate a specific evaluation procedure for our proposed indices. While performing the evaluation, we consider margins with respect to a minimum safety function level and a time constraint along with their temporal changes. Additionally, for a simplified fast reactor (FR) plant model, we conduct a trial assessment of the recovery capacity of the system to ensure system safety based on the concept of new indices. Further, the applicability of the response reliability evaluation method to FR plants is discussed based on the viewpoints of reflecting the characteristics of each reactor type.