Insights from On-Going PRA Studies

Earlier papers (Ref. 1, 2) dealt with the subject of use of probabilistic risk assessment (PRA) techniques in safety and licensing. The last year's paper discussed an approach to establishing quantitative safety goals in the regulatory process (Ref. 3). Other authors, notably Saul Levine (e.g. Refs. 4,5), dealt with the same subjects from the perspectives of the RSS (Reactor Safety Study). PRA, as a safety assessment tool, experienced a tortuous acceptance. Prior to the Three Mile Island accident, despite existence of several studies, PRA was on the way to extinction. In the aftermath of TMI it was noted that WASH-1400 contains a similar accident sequence. This understanding began the rebirth of WASH-1400 which was completed by virtue of Kemeny Commission and Rogovin Inquiry recommendations. As a result, use of PRA techniques is rapidly becoming widespread. The objective of this paper is to provide some insights from on-going plant specific PRA Studies. Generic studies have been prolifically discussed elsewhere and are listed here primarily for the sake of completeness. The paper discusses briefly Limerick (Ref. 6), Big Rock Point (Ref. 7) and Sequoyah (Ref.8) studies from the standpoint of an outside party.