Buildings ready to host ITER Neutral Beam power supplies

The Tokamak Complex, home to the world’s largest fusion reactor, stands out in the ITER site, its sheer size a measure of the ambition of the project. Around it is a dense landscape of supporting infrastructure. Europe is in charge of constructing most of the 39 buildings and areas on the platform. The past years have seen fast progress (flick through this gallery for a bird-eye view) and nearly all buildings are in place and ready to house equipment.

The construction teams are closing the year with two more checks on the delivery list. The two buildings hosting the power supplies for Neutral Beam Heating have been completed and handed over to ITER Organization. Fusion for Energy (F4E) worked with Demathieu Bard to build both facilities, located next to the Tokamak Complex’s north wall. This achievement will lead to the successful closure of the contract with the French firm, signed in 2019.

“Demathieu Bard entered the project when site construction was well underway and quickly got up to speed. In six years of design and works, we have erected four buildings and three bridges, installed building services in several others and built two load centres and two external areas,” sums up Eric Brault, F4E Project Manager. “We’re proud of our contribution to this world-class project. We achieved it thanks to the expertise of a long chain of engineers, designers, workers, including our subcontractors. A collaborative spirit, smart planning, and pragmatism helped us deliver on schedule,” says Sébastien Berne, Major Project Director of Demathieu Bard.

The two new buildings will not remain empty for long. From next year, they will start receiving equipment to become the electrical powerhouse of one of ITER’s main heating systems. An array of converters, transformers, rectifiers and other devices will work to generate -1MV ultra-high voltage. This unprecedented power level will feed the Neutral Beam injectors to accelerate particles, which will be neutralised and fired into the plasma, delivering up to 16.5MW of heating.

Works in the area started in 2020, constructing the galleries that now lie hidden below ground. These reinforced concrete corridors route the busbars towards the injectors inside the Tokamak Complex. Later, the teams covered them with a concrete slab and erected the two buildings on top.

The largest building stands 25 meters tall and stretches 86 meters in length, supported by a structure of nearly 1000 tonnes of steel. Inside it will be some of the most powerful and complex electrical systems on site. In fact, the building includes two separate halls for the High Voltage Decks (massive insulating cages made in Europe) and their Bushing Assemblies, avoiding the risk of interference with other equipment.

The smaller building will host the lower voltage systems. Above them, a dense cabling network will run along a set of trays fixed to the ceiling. F4E and its contractor worked together to design a reinforced roof structure capable of bearing the cables’ heavy load. Between both buildings, the teams built an outdoor area for the large high-voltage transformers. It’s a distinctive sight, with separation walls arranged almost like a line of dominoes — though their purpose is exactly the opposite: preventing the propagation of potential fire.

“This has been a challenging and rewarding project, in which civil engineering met electrical engineering to build an infrastructure that is critical to the fusion experiment,” concludes Romaric Darbour, F4E Programme Manager.