Gauss Fusion and UKAEA begin de-risking work on HEXA tritium breeding blanket

The HEXA tritium breeding blanket is designed to produce tritium from lithium, extract heat and shield surrounding systems from neutron exposure

(Image courtesy of Gauss Fusion)

Gauss Fusion has signed a memorandum of understanding with UKAEA that gives its HEXA tritium breeding blanket a framework for working with the LIBRTI programme. The release describes the larger LIBRTI experiment as a potential one, with initial work confined to science and engineering de-risking. Gauss Fusion’s CEO, Dr Uwe Bau, calls it a staged approach that lets the company de-risk HEXA progressively.

What the UKAEA agreement covers for the HEXA tritium breeding blanket

LIBRTI gives industry a route to test and demonstrate tritium breeder technologies, and the MoU sets out how Gauss Fusion and UKAEA will work together within it. The near-term scope is de-risking, with a larger LIBRTI experiment involving HEXA still described as a possibility.

HEXA is Gauss Fusion’s modular breeding blanket concept, designed to produce tritium from lithium while extracting heat and shielding surrounding systems from neutron exposure. It sits within a wider effort to develop and qualify the technologies a power plant will need.

Dr Uwe Bau, Gauss Fusion’s CEO, said the staged approach lets the company de-risk HEXA progressively and build evidence for its next development stages. Dr James Wade-Zhu, Lead for Experiments on LIBRTI at UKAEA, pointed to the work ahead, with the two teams set to develop technical, materials and safety concepts in the coming months. UKAEA’s view is that those concepts are what enable demonstration and testing of breeder blanket technology.

What the LIBRTI testbed offers a tritium breeding blanket developer

UKAEA is converting a Culham Campus building to hold a large neutron source inside a shielded blockhouse, with surrounding rooms for assembling and dismantling multitonne blanket prototypes. Customers will bring engineering-scale prototypes there to show they can produce tritium under neutron exposure, and UKAEA specifies a commercially available 14 MeV source. The programme is set to invest approximately £220 million between 2023 and 2030.

Tritium production at the site also carries a significant safety case. UKAEA’s hazard list for breeder work generally includes toxic constituents such as lead and beryllium, fire risk where lithium sits near water, and acidic species. Wade-Zhu’s reference to safety concepts puts that work alongside the technical and materials questions.

How tritium breeding blanket qualification fits the GIGA plant programme

Gauss Fusion is developing GIGA, its system-level architecture for stellarator power plants. When the Conceptual Design Report launched in October 2025, Frédérick Bordry, then Gauss Fusion’s CTO, said it tackles the toughest industrial challenges standing between fusion science and fusion power, including development of a closed tritium fuel cycle.

Future plants must breed enough tritium to replace what they consume, Bau said. UKAEA gives LIBRTI a matching aim, to demonstrate net tritium production.

Building the evidence base before a larger experiment

UKAEA has said LIBRTI exists to move from science experiments to giving the supply chain the confidence to support future power plants. For HEXA, that starts with the technical, materials and safety work the two teams will take up in the coming months, with any larger experiment following. Bau describes de-risking the blanket progressively, with each stage building the evidence for the next.

Stay ahead in the fusion revolution explore more breakthroughs from leading innovators in clean energy technology.