RISK ANALYSIS AND REGULATORY SAFETY DECISIONS

摘要

The rationale for application of the proposed Swiss probabilistic safety criteria to existing and future generations of nuclear power plants is provided. These proposed criteria form the basis of a framework for regulatory and operational safety decision making, using uncertain, plant specific probabilistic safety analysis (PSA) results. For existing plants, the approach proposes to use probabilistic safety criteria to determine if major plant specific back-fits are justifiable on the basis of risk benefit analyses. Less significant procedural modifications (i.e. additional emergency operating procedures) are proposed to be evaluated using relative safety gains determined on the basis of a selected number of uncertain PSA calculated risk measures. The new plants are expected to achieve a much higher standard of safety, and therefore must be able to accommodate severe accidents within their design basis envelope, thus reducing and/or eliminating the perceived severe accident uncertainties via innovative accident prevention and mitigation design features.