The UK National Nuclear Laboratory (NNL) and the Japan Atomic Energy Agency (JAEA) have signed a memorandum of collaboration (MOC) on coated particle fuel for use in high temperature gas-cooled reactors (HTGRs).

The MOC, signed by JAEA President Koguchi Masanori and NNL CEO Paul Howarth, focuses on the development of fuel manufacturing technology for an HTGR demonstration reactor. It also includes and licence arrangements defining the intellectual property rights. JAEA said it will "collaborate with NNL to establish HTGR fuel manufacturing technology, utilising the unrivalled experience from Japan, to establish a manufacturing route for fuel for HTGR demonstration reactors in both the UK and Japan".

The coated particle fuel (CPF) is especially robust because each kernel of uranium is coated in four protective layers. It is already being produced by NNL at its laboratory in Preston, in northwest England. However, the purpose of the collaboration is to learn from the experience in Japan where the fuel has been manufactured for use in the High Temperature Engineering Test Reactor (HTTR).

JAEA and NNL have been cooperating for more than two decades on areas including the nuclear fuel cycle and radioactive waste management as well as advanced reactors. The MOC follows a memorandum of cooperation in the field of HTGRs and a memorandum for collaboration on the next stage of the UK HTGR Demonstration Reactor programme signed in September 2023.

UK and Japan expect HTGRs to contribute to decarbonisation through the supply of hydrogen and high-temperature steam to the processing, steelmaking and chemical industries, considered difficult to decarbonise, to achieve carbon neutrality by 2050. JAEA is collaborating with NNL to demonstrate Japanese HTGR technology outside of Japan and to promote its "social implementation" with the aim of returning the decarbonisation technology to Japan.

Emma Vernon, NNL's Vice President for Government and New Build, said: "This agreement will further strengthen the relationship between the two laboratories and demonstrates the importance of international collaboration to innovate together to progress advanced nuclear technologies. The collaboration will bring together the skills that JAEA have developed in coated particle fuel over decades, along with the world class facilities that we have developed here in the UK to deliver sovereign fuel. This is critical technology to enable the UK to achieve net zero."

In December 2022, the UK government announced funding of £60m ($75m) for research into HTGRs, classed as advanced modular reactors (AMRs), with the aim of implementing a demonstration project by 2030. Phase A of the AMR R&D programme produced six successful bidders for pre-FEED (front end engineering design) studies for reactor demonstration and fuel demonstration. Phase B, which ends on February 2025, is "an open, competition-based programme designed to produce up to two HTGR FEED mature enough to enter regulatory review, carry out associated research and development activities, and produce robust delivery plans for a potential Phase C".

In July last year, the UK Department for Energy Security & Net Zero (DESNZ) selected a team comprising NNL and JAEA as one of the Phase B projects for which they received funding of £31m. DESNZ announced that Phase B would also push the development of an advanced fuel required for AMRs, through the Coated Particle Fuel – Step 1 Programme. NNL, working with JAEA, has been selected to deliver this fuel programme which will build expertise, knowledge and collaboration on coated particle fuel fabrication and scale-up activities. The aim of Phase C is the licensing, construction and operation of an HTGR in the early 2030s.

Following the MOC signing ceremony, the NNL delegation will visit the HTTR at Oarai, Japan. Last month, a delegation from NNL was invited to be present at the demonstration of the inherent safety features of the HTTR. This reactor is designed to cool down through natural processes even when the primary coolant flow is blocked, and the control rods are not inserted.

Nassia Tzelepi, NNL’s Technical Lead for the AMR Research, Development and Deployment Programme attended the test. “The JAEA team ran the reactor at 100% power (30MW) and an outlet temperature of 850 ˚C and then stopped the forced helium gas coolant,” she said. “As expected, after a short time, the reactor automatically decreased power and remained stable. In addition, the fuel, where the uranium kernel is encased in four layers comprising silicon carbide and carbon retained its integrity. It was an historic moment for the whole industry, and I was very excited to be a part of it.”

Image courtesy of JAEA