MDEP Design-Specific Common Position CP-EPRWG-02. Common position addressing Fukushima Daiichi-related issues

A severe accident involving several units took place in Japan at Fukushima Daiichi nuclear power plant (NPP) in March 2011. The immediate cause of the accident was an earthquake followed by a tsunami coupled with inadequate provisions against the consequences of such events in the design. Opportunities to improve protection against a realistic design basis tsunami were not taken. As a consequence of the tsunami, safety equipment and the related safety functions were lost at the plant, leading to core damage in three units and subsequently to large radioactive releases (INES 7). Several studies have already been performed to better understand the accident progression and detailed technical studies are still in progress in Japan and elsewhere. In the meantime, on-going studies on the behaviour of NPPs in very severe situations, similar to Fukushima Daiichi, seek to identify potential vulnerabilities in plant design and operation; to suggest reasonably practicable upgrades; or to recommend enhanced regulatory requirements and guidance to address such situations. Likewise, agencies around the world that are responsible for regulating the design, construction and operation of EPR plants are engaged in similar activities. The MDEP EPR Working Group (EPRWG) members consist of members from the United States, the United Kingdom, France, Finland, China, India and Sweden. Because not all of these countries have completed the regulatory review of their EPR applications yet, this paper identifies common preliminary approaches to address potential safety improvements for EPR plants, as well as common general expectations for new nuclear power plants, as related to lessons learned from the Fukushima Daiichi accident or Fukushima Daiichi-related issues. After the safety reviews of the EPR design applications that are currently in review are completed, the regulators will update this paper to reflect their safety conclusions regarding the EPR design and how the design could be enhanced to address Fukushima Daiichi-related issues. The common preliminary approaches are organised into five sections, namely, external hazards, reliability of safety functions, accidents with core melt, spent fuel pools, and emergency preparedness in design, supplemented by appendices related to areas where further studies were identified as necessary