DETERMINATION OF INPUT DATA FOR PROBABILISTIC SAFETY ASSESSMENT

The application of probabilistic safety assessment in decision process es depends to a great extent on the quality of the input data. The pla nt specific acquisition of these data must be performed in a way which allows a reliable prediction of system failures in the future. Comfor table computer tools are available to facilitate data processing and t o make use of data that are already available via the computerized pla nt information system. The correct classification of failure occurrenc es with respect to the PSA relevant failure modes requires thorough ev aluation of all information available in maintenance records, test rep orts, and licensing event reports. The flow of information relevant to future data acquisition must be properly organized The application of generic common cause failure data requires careful evaluation of the underlying failure causes and of the level of defence achieved in the plant under consideration to prevent too pessimistic analysis results.