MHI to lead development of Japanese HTGR

Wednesday, 26 July 2023

As the core company for this project, MHI will coordinate R&D, design and construction of the HTGR demonstration reactor that ANRE plans to put into operation in the 2030s.

"The selection of MHI as a core company reflects the recognition of its wealth of experience with the development of the HTGR, its proactive efforts in research and development, and its vast technical capabilities," the company said. "MHI will utilise and apply its accumulated technological expertise in the development of the HTGR demonstration reactor."

MHI has been pursuing development of HTGRs since the 1970s, and has accumulated technologies through its role as the principal company for the construction of a High Temperature Engineering Test Reactor (HTTR) for the Japan Atomic Energy Agency (JAEA). JAEA began research and development of HTGRs in 1969.

The 30 MWt graphite-moderated helium gas-cooled HTTR achieved first criticality in November 1998 and reached full power operation in 2001. It demonstrated stable heat at 950°C over 50 days in 2010. Its fuel is ceramic-coated particles with low-enriched (average 6%) uranium incorporated into hexagonal graphite prisms, giving it a high level of inherent safety. It is designed to establish a basis for the commercialisation of second-generation helium-cooled plants running at high temperatures for either industrial applications or to drive direct cycle gas turbines. The reactor resumed operation in July 2021, having been idle since February 2011 when it was taken offline for planned inspections.

In addition, since April 2022, MHI has participated in a demonstration programme to produce hydrogen using the HTTR, partnering with JAEA to connect a hydrogen production plant to the HTTR as part of a demonstration test for hydrogen production. Under the programme, the determination of specific renovations necessary to connect the hydrogen production plant, along with the licensing procedure, equipment modifications and testing, will be conducted in stages. In addition, in order to advance the hydrogen production technology in the HTTR in the future, they will consider increasing the size of some equipment (for example, the high-temperature isolation valve) to enable large-scale hydrogen production, and combine it with the high-temperature gas reactor.

Japan's Basic Energy Plan - approved by the government in October 2021 - states that high-temperature gas reactors will be used in the production of hydrogen. In addition, the Green Growth Strategy for 2050 Carbon Neutral (released in June 2021) says it will be necessary to utilise the HTTR to produce large quantities and inexpensive carbon-free hydrogen by 2030.

Earlier this month, MHI was selected by the Japanese government to lead the conceptual design of a demonstration sodium-cooled fast reactor that is to enter operation in the 2040s. MHI will oversee both the conceptual design as well as R&D for the reactor in partnership with Mitsubishi FBR Systems. The conceptual design work for the new reactor is scheduled to begin in fiscal 2024.