The Japan Atomic Energy Agency (JAEA), Japan Atomic Power Company (JAPC), Mitsubishi Heavy Industries (MHI), and Mitsubishi FBR Systems (MFBR) have signed an Arrangement for R&D Cooperation for research, development and design review of fast reactors with the French Alternative Energies and Atomic Energy Commission (CEA – Commissariat à l’énergie Atomique et aux énergies Alternatives), EDF and Framatome.
Under the Arrangement, Japan’s experience from the Joyo and Monju fast reactors and France’s experience from the Phénix, and Superphénix reactors will be used to advance research and development of severe accidents, structural materials, core materials, fuel technology, numerical simulation tools, design review, and design requirements for the Japanese demonstration fast reactor.
The 600 MWe demonstration reactor is based on an integrated SFR architecture (pool-type reactor) already developed and implemented in France. At the request of its Japanese partners, Framatome will provide feedback and design evaluation both on the technology and the architecture of this reactor type.
The Joyo sodium-cooled fast reactor, in Oarai Town, Ibaraki Prefecture, which began operation in 1977, is Japan’s only fast reactor. Joyo was shut down in 2007 after a test subassembly became jammed in the reactor vessel. Special equipment had to be designed to retrieve it, which finally took place in 2014. JAEA is aiming to restart the reactor in the second half of fiscal 2026 after completing safety construction. Monju, which achieved criticality in 1994, was shut down in 1995 after a sodium coolant leak and fire. It was restarted in 2010 but was shut down three months later after a fuel handling machine was accidentally dropped into the reactor during a refuelling outage. It was permanently closed in 2016.
France’s Phénix, and Superphénix have both been decommissioned. The 233 MWe (590 MWt) Phénix was a prototype fast breeder that operated from 1973 to 2009. The 1,242 MWe Superphénix was intended to reprocess nuclear fuel from conventional nuclear reactors, while also generating its own power. Construction began in 1974 but cost overruns, delays and public protests delayed grid connection until 1986. It was powered down in 1996 for maintenance, and while closed faced court challenges that prevented its restart and it was closed permanently. CEA was commissioned by the French government to develop two fourth generation fast reactors including Astrid Advanced Sodium Technological Reactor for Industrial Demonstration) in 2006, and it was decided in 2009 to make Astrid a high R&D priority. However, the project was cancelled in 2019.
In December 2019, MHI and MFBR, together with JAEA, signed an agreement to cooperate on the development of fast reactors with Framatome and the CEA. The General Arrangement, which summarises details of fast reactor cooperation between Japan and France, has now been updated by Japan’s Ministry of Economy, Trade & Industry and Ministry of Education, Culture, Sports, Science & Technology and France’s CEA.
Following the update JAEA, MHI and MFBR signed a Design Cooperation Implementation Arrangement for Sodium-cooled Fast Reactors with Framatome. This calls for cooperation, taking lessons from France’s experience to develop the design and design evaluation of equipment and systems that the Japanese side considers necessary for the Japanese project.
“Framatome is proud to be able to share its experience in developing this technology with our Japanese partners,” said François Billot, Framatome Executive Vice President, Offers & Projects. “This cooperation will contribute to reinforcing and maintaining the skills acquired by Framatome in the field of sodium-cooled fast reactors. This new agreement strengthens the cooperation that began 10 years ago.” Framatome noted the agreement marks the beginning of its contribution to the new Japanese programme for the development of a demonstration SFR.
“With the conclusion of these implementing arrangements, the development track record and operating experience in France will be reflected in the conceptual design of the Japanese demonstration fast reactor and associated research and development in Japan, promoting the development of fast reactors in Japan and in France,” the Japanese partners said in a joint statement.
