Development of Resilience Evaluation Method for Nuclear Power Plant (Part4: Concept of System Safety on Operating Nuclear Power Plants)
宮野 廣 Hiroshi MIYANO 山口 彰 Akira YAMAGUCHI 出町 和之 Kazuyuki DEMACHI 高田 孝 Takashi TAKATA 荒井 滋喜 Shigeki ARAI 杉山 直紀 Naoki SUGIYAMA
Accident Management and System Safety Resilience Index Safety Assessment Severe Accident
Abstract The total system design on Nuclear Plant ensures “Nuclear safety” with making practically achievable efforts to prevent and mitigate nuclear and radiological accidents. The performance based system design with “Defence in depth (D-I-D)” has been laid out as the key means in “preventing accidents”, “controlling escalation to serious consequences”, and “mitigating impact to the public”. D-I-D is extended to the management of severe accidents, and is an approach intended to provide protection against the development of a wide variety of events by means of redundant, diverse and independent protective barriers. By combining the concepts and risk assessment discrete "defense in depth", it can be expressed as a risk level corresponding to the degree of each layer of the D-I-D. Situation that exceeds the normal operation becomes an abnormal situation in which more than even the design criteria, various AM measures are taken. The ability of the resilience to recover the function until the required function, and quantified in risk level as a safety corresponding capability of the system, expressed as a resilience index. By using the resilience index, safety capability of the plant system can be quantitatively grasp, that whether the safety by the AM measured is how much improvement, what is good to select which means, etc. it can be used to for the decision.