PROBABILISTIC SAFETY ASSESSMENT FOR NON-FULL-POWER STATES OF NUCLEAR-POWER-PLANTS

It has become obvious in the last few years that non-full-power states may have a significant impact on the safety of a nuclear power plant. In a logical extension of the application of probabilistic safety assessment (PSA), plant states other than power operation states are analysed now in nearly all countries operating nuclear plants. The application to events during low-power and shutdown states requires further development of PSA methodology in many areas. This paper describes the international state of the art and presents some details of studies performed for a pressurised water reactor and a boiling water reactor.