A preliminary site risk assessment

Abstract

Since the Fukushima accident, interest in the site probabilistic safety assessment (PSA) has increased worldwide. However, the standard process for the site risk assessment (SRA) has not yet been established. In addition, most of these studies have focused on the level 1 and 2 PSA. The offsite consequences of the multi-unit accidents may differ from that of the single-unit accidents, so that the full-scope site PSA is essential. In this paper, the preliminary site risk assessment has been performed. The level 1 multi-unit probabilistic safety assessment (MU-PSA) methodology considering the inter-unit dependency was established and carried out. And the mapping table method was adopted in the level 2 MU-PSA. For the level 3 MU-PSA, the grouping method was adopted to reduce the number of the source-term category combinations. Then, the early fatality risk and the latent cancer risk from the accidents in a site were estimated and the tendency of the site risk was analyzed. The process of performing a full-scope site PSA for a site with more than 2 units of varied reactor types presented through this application could contribute to developing the SRA methodology, risk metrics, and safety goals.