This week, two significant announcements have emerged from the United Kingdom’s advanced reactor sector.

On June 14, Rolls-Royce, the United Kingdom National Nuclear Laboratory, and the Japan Atomic Energy Agency announced that they had signed two trilateral memorandums of cooperation to collaborate on “advanced modular reactor (AMR) technology, specifically high-temperature gas-cooled reactors (HTGR), and the coated particle fuel these reactors will use.”

Separately, on June 16, Bellevue, Wash.–based TerraPower announced that its Natrium reactor design has been formally submitted for U.K. regulatory review. The company also announced the formation of a new subsidiary, TerraPower UK Ltd.

U.K.-based Cavendish Nuclear, a subsidiary of Babcock International, will work with Amentum on the next phase of work supporting the decommissioning of Japan’s Monju prototype fast reactor under a contract awarded by the Japan Atomic Energy Agency.

Concept art of a tank type sodium-cooled fast reactor. (Image: MHI)

The Japanese government has chosen Mitsubishi Heavy Industries (MHI) to head up the conceptual design and research and development of a demonstration sodium-cooled fast reactor, the Tokyo-based engineering firm announced recently.

MHI is to oversee the work in partnership with Mitsubishi FBR Systems Inc. (MFBR), an MHI Group engineering company established in 2007 to develop and design fast breeder reactors.

Conceptual design work is scheduled to commence in fiscal year 2024, with operation of the unit slated for the 2040s.

Reactor roadmap: According to MHI’s announcement, 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 several types of technologies to be developed following a competition among private-sector companies. The roadmap was subsequently revised by the Cabinet in December 2022, at which time two decisions were made: (1) to select a sodium-cooled fast reactor as the target of the conceptual design of the demonstration unit and (2) to select a manufacturer to serve as the core company in charge of the reactor’s design and requisite R&D.

President Joe Biden and Prime Minister Fumio Kishida of Japan have announced the successful removal of more than 30 kilograms of high-enriched uranium from three Japanese sites to the United States. The news came in a May 23 statement from the Department of Energy’s National Nuclear Security Administration.

Natrium, a 345-MWe sodium fast reactor with a molten salt energy storage system, was developed by TerraPower and GE Hitachi Nuclear Energy. TerraPower is planning to build the first Natrium demonstration reactor by 2028 with 50-50 cost-shared funding of about $2 billion from the Department of Energy’s Advanced Reactor Demonstration Program. And for the requisite data and testing of reactor components to support that deployment, TerraPower is looking to Japan—a country with decades of experience developing sodium fast reactor designs and testing infrastructure.

Noting the challenges Japan will face in managing the nuclear waste that will be generated from decommissioning 79 of its nuclear research and development facilities, the International Atomic Energy Agency is recommending that the country prepare for delays in the development of disposal facilities and provide appropriate waste storage capacity for the interim period.

The recommendation was one of several that a team of IAEA experts provided to the Japan Atomic Energy Agency after reviewing the agency’s 70-year decommissioning program, called the “Back-End Roadmap,” and contained in the report, ARTEMIS Review of JAEA Back-End Roadmap, which was released on June 22,