Adaptation of the PIRT methodology to the Severe Accident domain

Severe Accidents (SAs) dominate the risk associated with the commercial production of nuclear energy. Despite the major achievements made in their understanding, upcoming new technologies such as Advanced Technology Fuels (ATFs) and Small Modular Reactors (SMRs), more stringent safety requirements, optimization of SA management, and other factors, point the need for an efficient use of research resources in the years to come. The SEAKNOT project (SEvere Accident research and KNOwledge managemenT for LWRs), coordinated by CIEMAT, was born to address this need in all and every aspect. The present article describes how the PIRT (Phenomena Identification and Ranking Table) approach has been adapted to the entire SA domain to prioritize forthcoming research. A 13-step methodology aimed at source term (ST) release to the environment or its potential prevention/mitigation is outlined with particular emphasis on the challenges addressed while adapted. At the time this article is being written, the phenomena ranking process has already started