Design Safety Considerations for Water Cooled Small Modular Reactors Incorporating Lessons Learned from the Fukushima Daiichi Accident

The global future deployment of advanced nuclear reactors for electricity generation depends primarily on the ability of nuclear industries, utilities and regulatory authorities to further enhance their reliability and economic competitiveness while satisfying stringent safety requirements. The IAEA has a project to help coordinate Member State efforts in the development and deployment of small and medium sized or small modular reactor (SMR) technology. This project aims simultaneously to facilitate SMR technology developers and potential SMR users, particularly States embarking on a nuclear power programme, in identifying key enabling technologies and enhancing capacity building by resolving issues relevant to deployment, including nuclear reactor safety. The objective of this publication is to explore common practices for Member States, which will be an essential resource for future development and deployment of SMR technology. The accident at the Fukushima Daiichi nuclear power plant was caused by an unprecedented combination of natural events: a strong earthquake, beyond th e design basis, followed by a series of tsunamis of heights exceeding the design basis tsunami considered in the flood analysis for the site. Consequently, all the operating nuclear power plants and advanced reactors under development, including SMRs, have been incorporating lessons learned from the accident to assure and enhance the performance of the engineered safety features in coping with such external events. In response to the Fukushima Daiichi accident, the IAEA established an Action Plan on Nuclear Safety. The preparation of this publication was carried out within the framework of the IAEA Action Plan on effectively utilizing research and development. The main objective of this publication is to present technology developers and user s with common considerations, approaches and measures for enhancing the defence in depth and operability of water cooled SMR design concepts to cope with extreme natural hazards. Indicative requirements to prevent such an accident from recurring are also provided for States planning to adopt water cooled SMR designs and technologies. The IAEA gratefully acknowledges the information on technology and safety aspects provided by SMR design organizations and information regarding technical requirements provided by several Member States. The IAEA officers responsible for this publication were M.H. Subki of the Division of Nuclear Power and M. Kim of the Division of Nuclear Installation Safety.