The probabilistic safety analysis of the Muehleberg nuclear power plant

The important results of the PSA probablistic safety analysis carried out for the Muehleberg nuclear power station (KKM) in 1988-1990 (Muehleberg Safety Assessment, MUSA) are presented. MUSA consists of a Level 1 and Level 2 analysis. Altogether, the analysis covers some 40 internal trigger events and the external triggers fire, flood, earthquake and plane crashes. MUSA included a detailed analysis of the behaviour of the unit in the event of a failure of the fast reactor shutdown system (ATWS), a failure analysis of the safety vessel and full analysis of operator actions. MUSA showed a meltdown frequency for KKM of less than 10-5 per year for all internal and external trigger events. It was also shown that the source terms for more than 90% of all possible accident scenarios were very low and well below the yardsticks used by the authorities in planning emergency action. 5 tabs