Addressing off-site consequence criteria using Level 3 PSA — Phase 1 Status Report
Andrew Wallin Caldwell, Anders Olsson, Malin Nordqvist, Gunnar Johanson, Jan-Erik Holmberg, Carl Sunde, Ilkka Karanta,
Based on an inquiry from the Nordic PSA Group (NPSAG) and the Nordic Nuclear Safety Research group (NKS), a consortium of Swedish nuclear risk consultancies (Lloyd's Register Consulting, ES-Konsult and Risk Pilot) and the Finnish research institute VTT has begun a multi-year study of Probabilistic Off-site Consequences Analysis, commonly referred to as Level 3 Probabilistic Safety Assessment (Level 3 PSA). Level 3 PSA is infrequently performed and generally regarded as a less developed analysis when compared to Level 1 and Level 2 PSA. Interest in the Nordic countries has been spurred based on new nuclear construction projects and plans. These activities have raised interest in objective, risk-based siting analyses for new nuclear reactors in order to better understand the risks of off-site consequences in the wake of the multi-unit disaster at the Fukushima Daiichi site. The objective of this study is to further develop understanding within the Nordic countries in the field of Level 3 PSA, in order to determine the scope of its application, its limitations, the appropriate risk metrics, and the overall need and requirements for performing a Level 3 PSA. The project's first year focused on the development and analysis of an industrial survey about Level 3 PSA, which included several workshops and meetings with Nordic utilities, regulators, and safety experts. Level 3 PSA risk metrics including health, environmental, and economic effects have been researched and discussed in the first year's project report. The project has generated significant interest internationally and has interfaced with international organizations including the IAEA and the American Nuclear Society. The long term objective of the work is to set the foundation for performing a "state-of-the art" Level 3 PSA for Nordic conditions.