Prospects for use of probabilistic safety criteria

Probabilistic Safety Assessment (PSA) is increasingly being used as a technique to analyse in a quantitative way the degree of protection against severe accidents of potentially hazardous industrial installations. It is thus necessary to develop Probabilistic Safety Criteria (PSC) which allow the quantitative results of PSAs to be judged. The paper reviews why it is necessary, and which type of PSC is needed for the various uses made of PSA at present. It then summarizes the status of PSC developments based on examples of various countries. It is recommended to develop a consistent set of PSC at all levels: 10-7 per year for individual risk from severe accidents; 10-6 per year for major releases of radioactive materials, containment performance better than 10-1 failures per demand, 10-5 per year for coremelt, and criteria at the level of safety function/systems for reference designs based on completed level 1 PSAs. It should be noted that PSC provide for a consistent approach to radiation protection and nuclear safety and to nuclear safety and industrial safety in general. (orig.)