2017

Tyrväinen, Tero; Häggström, Anna; Bäckström, Ola; Björkman, Kim

In this study, a methodology is outlined to estimate the importance of multi-unit accidents for a site with more than one reactor unit. The suggested approach is based on: - Identification of dependencies - Qualitative and quantitative screening - Estimation of frequencies/probabilities for screened in dependencies - Calculation of the Multi-Unit Core Damage Frequency (MUCDF) or Multi-Unit Large Early Release Frequency (MULERF) using primarily conditional quantification of single unit models (together with the frequency/probability of the dependence) - Sum of the MUCDF/MULERF for the identified dependencies to estimate the total MUCDF/MULERF The approach is considered a conceptual approach, and there are a number of outstanding issues that could be studied further. Most importantly, the approach needs to be validated using full scope PRA models.