Nuclear Energy Agency (NEA) – Review of progress in severe accident research for existing and modern reactor designs

The Nuclear Energy Agency (NEA) supports the efforts of member countries to improve their ability to manage severe accidents through cooperative activities led by the Working Group on Accidents and Management (WGAMA).

As part of this work, the NEA co-organized the 11th^th Review Meeting on Severe Accident Research (ERMSAR 2024) from 13 to 16 May in Stockholm, Sweden. Participants reviewed progress in severe accident research, including the behaviour and coolability of corium inside and outside ships, hydrogen risk management, containment behaviour and the release of radioactive substances.

Participants also addressed severe accident analysis for existing and modern reactor designs, with sessions devoted to small modular reactors (SMRs), accident-tolerant fuels and fast reactors. The conference was co-organised with the European Commission, the International Atomic Energy Agency (IAEA), the Swedish Safety Authority, the Swedish Royal Institute of Technology and the Karlsruhe Institute of Technology.

During the plenary sessions, experts with long-standing experience in severe accident research, including WGAMA Chair Hideo Nakamura from the Japan Atomic Energy Agency (JAEA), shared their experiences and reflections on developments in the sector. Participants then also discussed regulatory perspectives and approaches to severe accident management in SMRs and joint severe accident research in this field, with plans being developed at the EC, IAEA and NEA. The conference, which was attended by 157 participants from 21 countries, underlined the need to integrate severe accident research and knowledge, including lessons learned from the Fukushima Daiichi accident, into severe accident analysis to continuously improve accident prevention and mitigation in view of the extended operation of the existing fleet and to support the use of advanced designs. The next review meeting is planned for May 2026 in Madrid, Spain.