Proceedings of the 12th European Review Meeting on Severe Accidents Research (ERMSAR2026)

The 12th edition of the ERMSAR (European Review Meeting on Severe Accident Research) Conference was held from 18 to 22 May 2026 in Madrid, hosted and locally organized by CIEMAT, two years after the 11th edition in Stockholm. ERMSAR 2026 was organized within the framework of the EURATOM SEAKNOT project and NUGENIA Technical Area 2 of the SNETP Association, in cooperation with the International Atomic Energy Agency and the OECD Nuclear Energy Agency. The conference brought together 223 participants, including 35 students, from 27 countries. Scientific contributions originated from 84 institutions located in 26 countries, while 23% of the participants represented non-European Union institutions. The programme comprised 112 oral papers and 43 posters, making ERMSAR 2026 the largest edition in the historical series and confirming its role as a reference international forum fully devoted to severe accident research.