Mitsubishi Heavy Industries, Ltd. (MHI) has been selected as the core company in charge of the conceptual design of an demonstration fast reactor which the Japanese Government aims to place into operation in the 2040s. MHI will oversee both the conceptual design as well as research and development (R&D) for the sodium-cooled fast reactor in partnership with Mitsubishi FBR Systems, Inc. (MFBR), an MHI Group engineering company that handles the development and design of fast reactors. The conceptual design work is scheduled to commence in fiscal 2024.

Tank type sodium-cooled fast reactor (incorporating research results of METI-commissioned project)

In the strategic roadmap for fast reactor development adopted by the Japanese Cabinet in December 2018, a policy was defined to assess the efficacy of various types of fast reactors to be developed following a technological competition among private-sector corporations. The roadmap was subsequently revised by Cabinet decision on 23 December 2022, at which time two decisions were taken:

1. to select a sodium-cooled fast reactor as the target of the conceptual design of the demonstration reactor, set to get underway in fiscal 2024; and

2. to select a manufacturer to serve as the core company in charge of the fast reactor’s design and requisite R&D which would proceed with technology development in accordance with the goals and policy directions established by the Government.

In 2007, MHI was selected as the core company in charge of a research program which was focused on the practice uses of fast reactors. The selection was made by taking into consideration MHI’s technologies and experience cultivated through its participation in the development and construction of the Joyo experimental fast reactor (Oarai, Ibaraki) and Monju prototype reactor (Tsuruga, Fukui).

Subsequently, MHI, in partnership with MFBR, established in 2007, has been undertaking plant conceptual studies and R&D toward reactor realization. Considering the lessons learned from the Fukushima Daiichi accident in 2011, MHI proposed the concept of a safety-enhanced sodium fast reactor at the Generation IV International Forum (GIF), and, together with the Japan Atomic Energy Agency (JAEA), led a study on global safety standardization.

The resulting experience has been applied in the joint design and development of France’s next-generation fast reactors starting in 2014, as well as application of those results to a feasibility study regarding the reactor’s application in Japan, and a study of the plant concept is now under process.

MHI is also involved in the US-Japan cooperation program (signature of memorandum of cooperation on sodium fast reactor technology with TerraPower, LLC in 2022). These activities will enable faster reactor development and the establishment of in-house sodium testing facilities necessary for reactor R&D.