ITER’s first 5,200-ton vacuum vessel built to contain plasma for fusion reactions

The first of five vacuum vessel sectors for the International Thermonuclear Experimental Reactor (ITER) has been completed. Also known as the plasma chamber, the vacuum vessel sector provides a high-vacuum environment for the plasma, improves radiation shielding and plasma stability, and acts as the primary confinement barrier for radioactivity.

Once assembled, the vacuum vessel sector will measure an impressive 19.4 meters in diameter by 11.4 meters in height and will weigh approximately 5,200 ton.

The component was completed towards the end of August and is expected to depart from Italy soon. It will be delivered to Fos-sur-Mer, the industrial port of Marseille, where it will be loaded onto a massive trailer for transport to the ITER site. Europe’s remaining four sectors are in production and will be delivered in the next two years.

Vacuum vessel is a hermetically sealed steel container

“It is the achievement of so many years of work trying to respond to several technical challenges for this one-of-a-kind component,” said Fusion For Energy’s Technical Officer based in Westinghouse Andrés Dans Alvarez De Sotomayor.

“I remember witnessing the manufacturing of raw material , starting from the casting of the ingots, that become the small forgings and plates, which slowly transformed into this massive steel structure. How the works advanced in parallel in different factories and eventually all pieces were united under the same roof .”

The vacuum vessel, a hermetically sealed steel container, houses the fusion reactions and acts as a first safety containment barrier. Within its doughnut-shaped chamber, or torus, the plasma particles spiral continuously without touching the walls .

The larger vacuum chamber volume, the easier it is to confine plasma

ITER claims that in a tokamak device, the larger the vacuum chamber volume, the easier it is to confine the plasma and achieve the type of high-energy regime that will produce significant fusion power.

The ITER vacuum vessel , with an interior volume of 1,400 m³, will provide an absolutely unique experimental arena for fusion physicists: the volume of the plasma contained within the center of the vessel (840 m³) could be ten times larger than that of the largest operational tokamak currently in existence.

With the installation of the blanket and the divertor, the vacuum vessel will weigh 8,500 tonnes. The blanket modules lining the inner surfaces of the vessel will provide shielding from the high-energy neutrons produced by the fusion reactions. Some blanket modules will also be used at later stages to test materials for tritium breeding concepts, according to ITER .

ITER also claimed that forty-four openings, or ports, in the vacuum vessel would provide access for remote handling operations, diagnostics, heating, and vacuum systems.

“The production of sector 5 has been a fascinating learning curve for Europe and its industrial suppliers. We managed to overcome the technical challenges in production, and those of schedule, successfully.” said Joan Caixas, Fusion For Energy’s Project Manager for the Vacuum Vessel.

“We followed the manufacturing process with rigor and made progress with great care and confidence. This results from the meaningful collaboration between F4E, the AMW consortium, their sub-suppliers and ITER Organization, who took part to so many meetings, contributed to the revision of strategies, and travelled to so many of our factories.”