Europe’s fifth and final vacuum vessel sector has arrived at the ITER nuclear fusion project site in Cadarache, France. This represents the final delivery of Europe’s large-scale industrial components to the €22bn ($24.6bn) International Thermonuclear Experimental Reactor.
The sector was manufactured under a 16-year project by Fusion for Energy (F4E) – the European Union organisation managing Europe’s contribution to ITER – in collaboration with the AMW consortium, which includes Ansaldo Nucleare, Westinghouse Electric Company, and Walter Tosto. The component was completed at the Westinghouse facility in Monfalcone, Italy, and transported by French industrial logistics company DAHER by sea and land to its final destination in France.
The vacuum vessel acts as the central, stainless-steel heart of the ITER tokamak reactor. Its job is to provide a hermetically sealed, double-walled container that protects the internal environment from dust and air impurities while keeping the extreme fusion plasma – heated up to 150m degrees C – safely contained.
The completed chamber comprises nine D-shaped sectors. Europe was responsible for providing five sectors, while South Korea manufactured the remaining four. Fabricating Europe’s five kilometres of precise welding beads across a supply chain of at least 15 European companies.
When all segments are fully joined and welded into place, the final vacuum vessel will stand 11.4 metres high, measure 19.4 metres across, and weigh approximately 5,200 tonnes. With all sectors now delivered on-site, the assembly team is scheduled to have all nine pieces fully integrated in the tokamak pit by spring 2027.
Before the sectors can be welded into the reactor core, they must undergo a meticulous, multi-stage “assembly choreography”. Each 400-tonne sector is upended from its horizontal shipping layout into a perfectly vertical orientation. Inside the massive Assembly Hall, the sector is integrated with thermal shield panels and a pair of vertical, 310-tonne toroidal field magnet coils. This transforms the standalone sector into an 1,100-tonne sector module.
The completed module is lifted by an overhead beam and lowered into the Tokamak pit, where it sits on massive gravity supports. Six of the nine modules are already in position. Once the final sector modules are positioned in the pit (anticipated by mid-2027), teams will begin the highly complex task of welding all nine pieces together to form a perfectly hermetic, seamless steel ring.
In mid-2024, the ITER Organisation implemented an updated baseline schedule to correct for historical design changes, severe COVID-19 delays, and technical setbacks – specifically vacuum vessel welding defects and thermal shield corrosion. The original timeline scheduled First Plasma for 2025. The new strategy is based on a stepwise safety deployment. It targets the first scientifically robust deuterium-deuterium plasma operations in 2035. The milestone for full magnetic energy operations, maximum plasma current, and full deuterium-tritium fusion operations has been pushed to 2039.
These extensive delays and necessary component repairs have heavily driven up the total financial cost of the international project to €27bn. Despite the soaring budget, the project is now moving forward with significantly higher schedule efficiency and tighter project management.
South Korea has been a cornerstone partner for ITER, delivering its critical core components with unmatched schedule reliability and precision manufacturing. While Europe has now celebrated completing its last sector, South Korea finished and delivered all four of its assigned vacuum vessel sectors ahead of schedule, with the final piece arriving on-site in late 2024.
South Korea’s role became significantly larger than originally planned due to European delays. In the project’s early days, South Korea was only contracted to manufacture two sectors (6 and 1), while Europe was tasked with building the remaining seven.
When Europe faced major technical and scheduling delays, the ITER Organisation turned to South Korea. In 2016, ITER Korea and HD Hyundai Heavy Industries stepped in to absorb two additional sectors (7 and 8) under a KRW120bn ($89bn) contract. Manufacturing these sectors at shipyards in Ulsan required handling 45,000 inspection points and over 1.6 kilometres of precision welding per sector to maintain structural tolerances under a few millimetres.
Beyond the vacuum vessel, South Korea’s advanced industrial ecosystem has reliably supplied several other complex systems vital to the tokamak reactor. These include superconducting conductors & magnets; thermal shields and sector sub-assembly tools.
Through its domestic agency, supported by the Korea Institute of Fusion Energy (KFE), South Korea has used its strict timeline compliance to secure proprietary intellectual property. The ultimate goal is to leverage this unique technical expertise to jump-start the construction of K-DEMO, South Korea’s planned commercial fusion demonstration power plant.
At the ceremony marking receipt of the final vacuum vessel sector, F4E Director Marc Lachaise, said that the European vacuum vessel procurement programme could only have been completed through close integration with the ITER Organisation and other Domestic Agency partners. “This is an emotional moment for me and for others,” he said. “We can be proud of what we achieved.”
He added: “Europe’s final sector results from the strong partnership between F4E, the consortium of Ansaldo Nucleare, Westinghouse, and Walter Tosto. We worked as one team, in an integrated manner with ITER Organisation, and built on the lessons learnt from ITER Korea in producing the rest of the sectors.”
