A Quantitative Approach to Risk-Informed Safety Significance Categorization with an Early Expert Participatory

Abstract

A risk-informed safety significance categorization (RISSC) is to categorize structures, systems, or components (SSCs) of a nuclear power plant (NPP) into two or more groups, according to their safety significance using both probabilistic and deterministic insights [1]. In the conventional methods for the RISSC, SSCs are quantitatively categorized according to their importance measures for the initial categorization [2]. The final categorizations of SSCs, however, are qualitatively made by expert panel through discussions and adjustments of opinions by using the probabilistic insights compiled in the initial categorization process and combining the probabilistic insights with the deterministic insights. Therefore, owing to the qualitative decision-making process, the conventional methods have the demerits that they are very costly in terms of time and labour; and that it is not easy to reach the final decision, when the opinions of the experts are in conflict.