Application of risk-informed probabilistic and deterministic safety approach to estimate the risk of external events

This report presents the activities performed in the frame of LP1, Objective B (Accident consequences evaluation), task B3 of PAR 2014, ADP ENEA-MSE. The study addresses the safety assessment of nuclear power plants due to external events, adopting a risk informed approach. To this aim safety analysis is thus implemented with the evaluation of some specific probabilistic aspects, related e.g. to the multi-unit risk issue, as a complement to traditional deterministic investigations. To complement the hazard assessment, a deterministic investigation of an existing plant has been carried out. In doing that aging effects, as a consequence of loadings originated by the multiple accident event, have been considered in order to highlight possibly vulnerability.