Use of PRA and safety goals in nuclear power plant regulation

Probabilistic risk assessments (PRAs) have been performed on a number of nuclear power plants, both by the NRC and industry. The NRC has used risk perspectives gained from PRAs, both in an absolute as well as a relative sense, as an aid in making decisions on plant-specific as well as generic safety issues. However, substantial uncertainties pervade present-day risk assessments, which makes the application of the results of such analyses difficult at best in the regulation of nuclear power. Nonetheless, the Commission approved in January 1983 a policy statement on safety goals for public comment and a two year evaluation period. These safety goals include quantitative design objectives which could serve in the future as risk benchmarks for use by the NRC as part of the decision making process on matters relating to nuclear safety. While the Commission's policy statement explicitly excludes the safety goals from use both in licensing cases and in regulation for the two year evaluation period, PRA will be used generically and on a plant-specific basis more and more to assess the importance of new safety issues, prioritize resources within the agency, and test the adequacy of (or in some instances the need for) NRC's regulations.