UK and Japan sign agreement to collaborate on nuclear fusion developments

The agreement, signed as part of wider UK–Japan discussions during Japanese Prime Minister Sanae Takaichi’s recent visit to London, has formalised a framework for “joint research, engineering development and knowledge exchange” aimed at accelerating the commercial deployment of fusion power.

The Memorandum of Cooperation (MoC) builds on a broader UK–Japan nuclear fusion memorandum agreed in June last year identifying several technical areas for collaboration.

These include:

Plasma science and materials
Breeding blanket systems for tritium production
Whole-plant engineering and integration (including robotics and autonomous systems)
Fuel-cycle and safety technologies
Measures to improve the commercial affordability of fusion.

Representatives from both organisations said the new MoC will enable targeted collaborative projects, staff exchanges and shared use of facilities, with the aim of addressing “key scientific and engineering challenges” on the path to a commercially deployable fusion power plant.

Fusion has attracted substantial public and private investment in recent years, with projects such as the UK’s Spherical Tokamak for Energy Production (Step) programme and international efforts including Iter in France.

The UK and Japan have both outlined how fusion can be used for future energy security. The UK government has backed Step as a flagship domestic effort to build a prototype fusion power plant, while Japanese research institutions have long experience in magnetic confinement devices and tritium handling.

Minister for science, innovation, research and nuclear Patrick Vallance said: “This Memorandum of Cooperation between the UKAEA and Japan’s QST on fusion energy marks a significant step in strengthening our global partnerships and accelerating progress towards clean, secure energy.

“Britain is a world leader in the fusion industry, and the UKAEA working closely with international partners will help enable us to move ever closer to unlocking fusion’s potential to provide virtually limitless clean energy.

“This builds on backing the sector with over £2.5 billion and launching our national Fusion Strategy — supporting thousands of high-skilled jobs across the country, from Nottinghamshire to Oxfordshire and South Yorkshire.”

Yasuyoshi Kakita, vice-minister for policy coordination for the Ministry of Education, Culture, Sports, Science and Technology (MEXT), commented:

“We are very pleased with the conclusion of this Memorandum of Cooperation between the National Institutes for Quantum Science and Technology and the United Kingdom Atomic Energy Authority.

“The governments of Japan and the United Kingdom signed an MOC in June 2025, agreeing to deepen collaboration in research and development, skill and workforce development, and other areas.

“This institutional cooperation further concretizes the partnership between the two countries, and we look forward to the creation of outcomes that will be of value to both nations. In Japan’s new growth strategy, fusion energy has been designated as one of 17 key strategic areas, and efforts are underway to explore initiatives toward societal implementation, including research and development.

“We hope that this cooperation with the UK will contribute to accelerating the early realization of fusion energy.”

UKAEA chief executive Tim Bestwick said: “Fusion energy is a global challenge that requires international collaboration. This cooperation with QST strengthens our long-standing partnership with Japan in fusion-related technologies and creates new opportunities to combine our expertise to tackle key challenges in delivering fusion power.

“By working together, we can accelerate progress towards commercially deployable fusion and its long-term economic and energy benefits.”

QST president Shigeo Koyasu said: “Fusion energy research and development is essential to addressing global challenges. This collaboration with UKAEA provides a new opportunity to further strengthen the long-standing partnership between Japan and the United Kingdom in fusion energy development, while bringing together the expertise of both sides to tackle key challenges toward the demonstration of fusion power generation.

“Through this cooperation, I hope this will contribute to the creation of significant social and economic value, particularly in the fields of energy and the broader economy.”

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