Europe’s third ITER Vacuum Vessel sector completed

The third Vacuum Vessel sector made by Europe is on its way to ITER. The world’s largest fusion device will house the plasma inside a doughnut-shaped container, consisting of nine sectors (five from Europe, four from Korea) welded together. Fusion for Energy (F4E) is collaborating with the AMW consortium, formed by Ansaldo Nucleare, Westinghouse, and Walter Tosto, to manufacture Europe’s share.

Last weekend, Sector 9 left the Westinghouse Mangiarotti factory in Monfalcone (Italy) and set sail on the Adriatic Sea from the nearby harbour. It was a happy farewell: its departure for France, marked the completion on schedule of the project, meeting a deadline set three years ago. But getting there was not simple. The teams describe it as an “epic” industrial journey, in which perseverance and collaboration made the difference.

The ITER Vacuum Vessel is, by its size and geometry, a massive manufacturing challenge. The full chamber will measure 19.4 metres across and 11.4 metres high, and weigh approximately 5,200 tonnes (see a breakdown in this poster). It is made of stainless steel and designed to create a sealed high-vacuum environment for the plasma, which will be kept away from the walls thanks to powerful superconducting magnets. The component also provides radiation shielding and supports in-vessel equipment.

The fabrication of a sector starts with procuring large forged ingots of a stainless steel designed for ITER. The material is cut and machined into large steel plates. These are then joined to form four segments, which are later assembled and welded  to form the final sector. The chain involves thousands of tasks and over 150 professionals across various European companies. In the case of sector 9, each segment came from a different workshop: one from ENSA (Spain), one from Belleli (Italy), one from Walter Tosto (Italy), and the fourth made onsite in Westinghouse Mangiarotti, where they were all assembled.

Each Vacuum Vessel sector counts roughly 150 km of welding beads. This impressive extension increases the risk of deformations and non-conformities. When sector 9 was nearing finalisation, an inspection detected defects in some joints. The issue called for a ‘surgery’, an invasive repair that required opening a part of the sector and threatened to delay the project.

Despite the setback, the mindset of the teams quickly shifted into problem-solving to bring the project back on track. “The doubts were natural, but we always believed we could make it. Together with our partners, we revisited the design and devised a strategy to carry on with a vast number of manufacturing activities in parallel to the repairs”, explains Boris Bellesia, F4E Programme Manager.

With such time pressure, coordination was the only way forward. “The gamechanger was the close relation between F4E and the suppliers. We work as a single, integrated team,” says Andrés Dans, F4E Site Manager. Andrés has been in Monfalcone for over nine years. His office is next to the workshop, which he visits every day to see the sectors’ progress. “F4E’s presence on the ground is essential. We can follow the production first-hand and, when issues appear, we work out solutions directly with our partners,” he adds.

Throughout the process, Europe deployed experts in metrology and quality control to ensure compliance with the strict requirements. Teams of F4E and Westinghouse carried out daily checks on the welds and ran multiple campaigns of dimensional tests. The sector passed the final pressure and leak tests this month.

Its completion rewarded the efforts and offered a lesson beyond what’s purely technical: “When a united team believes in the target and pushes for it, no matter how difficult, you can arrive there. This will remain as an inspirational example to all of us,” stresses Miguel González, F4E Project Manager.

“We are proud of this outstanding milestone, achieved thanks to the dedication and skill of the AMW consortium staff and the effective collaboration with F4E and ITER Organization. The sector fully meets the stringent quality requirements of ITER and is ready for the subsequent assembly phases,” said Luca Ascione, Project Director for the AMW Consortium.

The component, protected in a custom metal stillage, will travel until Fos-sur-Mer, the industrial port of Marseille. It will then be loaded onto a large trailer and driven to the ITER site. There, it will join Europe’s sector 5, already on the Tokamak Pit, and sector 4, currently in sub-assembly. The remaining two European sectors are advancing, with their completion expected later in the year.