Evaluation of Site Core Damage Frequency of Multi-Unit Nuclear Power Plant Using Probabilistic Safety Assessment

The nuclear accident that took place at Fukushima (Japan 2011) highlighted the need for development of safety assessment of a multi-unit site. A systematic methodology to perform Level 1 safety assessment of a twin-unit site is presented using Probabilistic Safety Assessment (PSA) approach. The proposed approach quantifies risk from simultaneous failures of one or more systems due to internal initiating events (IE) and from shared system and components (SSC). Site core damage frequency (SCDF) is evaluated by developing an integrated multi-unit modal using fault trees as well as event trees. Major contributors to core damage are identified and analyzed from the minimal cut-sets using Risk-spectrum software.