Use of PSA to evaluate operating strategy compliance with operating policies and principles requirements

Within the Canadian regulatory environment, the Operating Policies and Principles (OP and Ps) define the operational safety philosophy and the limits and conditions for safe operation of our nuclear generating stations. As is the case with Technical Specifications, these limits and conditions are, for the most part, based on deterministic safety analysis and engineering judgement. However, unlike the Technical Specifications, the OP and Ps are intended to specify a minimum number of key constraints, and to specify them in very broad, general terms. A program to perform level 3 Probabilistic Risk Assessments (PRAs) at all of Ontario Hydro's nuclear generating stations is being undertaken by the corporation's design organization. At present, the PRA for one station, Darlington-A nuclear Generating Station, has been completed with work underway, or planned, for the remaining nuclear generating stations. This paper describes several examples to illustrate how the Darlington PRA has been used to evaluate proposed operating strategy compliance with the requirements embodied in the broad, conceptual limits defined in the OP and Ps. The paper concludes with a discussion of planned and potential future developments, including the more extensive use of PRAs in the day-to-day operation of Darlington Nuclear Generating Station. (author). 3 refs, 4 tabs