Development and Application of Level 3 PSA for the UK ABWR Generic Design Assessment

Abstract

A full scope Probabilistic Safety Assessment (PSA) was provided as an integral part of the safety case for the UK ABWR Generic Design Assessment (GDA) and this included a Level 3 PSA. The main objectives of the Level 3 PSA for GDA are to provide a demonstration of the compliance, for a single unit UK ABWR, with numerical risk targets defined in the UK Safety Assessment Principles and to support the ALARP assessment. This paper includes: • An overview of the methodology, PSA model development and illustration of some results. • A summary of the key assumptions made during the model development for the GDA phase of the project. Compliance with the numerical risk targets has been investigated through assessments against the individual off site risk from the facility (Target 7), facility dose bands (Target 8) and off site societal risk (Target 9). • Some conclusions of a peer review against the draft ASME/ANS standard for trial use (ASME/ANS RA-S-1.3, Feb 2016 for Level 3 Probabilistic Risk Assessment (PRA)), which was a key aspect of this study.