An Overview of Ontario Hydro's Nuclear Risk Assessment Program

Abstract

Ontario Hydro has in place a program of probabilistic risk assessment of its nuclear generating stations. As part of this program, a Probabilistic Safety Evaluation of the Darlington Station was completed in 1987. A similar study is currently underway for Pickering Nuclear Generating Station (NGs) A, to be followed by risk assessments of Bruce NGS A, Pickering NGS B and Bruce NGS B. This paper provides an overview of the program. It presents the methodology being used to identify and quantify accident sequences. Among the topics discussed is the utilization of event tree and fault tree logic models, supported by a component failure data base and human interaction modelling, to delineate accident sequences. The major results of the first application of this methodology in Ontario Hydro, viz., the Darlington Probabilistic Safety Evaluation, are presented. The paper also discusses the application of the logic models to operational decision making.