ITER Receives Last Vacuum Vessel Sector, Says All Core Machine Components Are on Site

The ninth and final sector of the ITER fusion machine's vacuum vessel has reached the construction site in southern France. The ITER Organization said on October 5, 2026 that the sector had been delivered on Friday, October 2. ITER calls it the last large component of the machine. With it, ITER says, all the components needed to complete the core machine are now on site.

This is a delivery milestone, not a finished machine. Six of the nine sectors had been lowered into the assembly pit by late July 2026. All nine still have to be joined into one vessel. ITER says the parts that go inside the vessel are still to come. ITER's published timeline lists the start of research operation in 2034. The site's fusion milestones tracker follows that schedule.

What arrived at ITER on October 2?

The component is called vacuum vessel sector #2. It is one of nine wedge-shaped steel sections that will be joined into a ring. World Nuclear News reports that each sector stands more than 14 meters tall and weighs 440 metric tons.

Europe built this one. Fusion for Energy (F4E) is the European agency that manages Europe's contribution to ITER. F4E says the sector left a Westinghouse factory in Monfalcone, Italy, and traveled by sea and land. The logistics company DAHER moved it. It was unloaded at the French port of Fos-sur-Mer. ITER says it left the port of Monfalcone in mid-September.

Staff and contractors gathered at the worksite on Monday, October 5, to mark the arrival. ITER Director-General Pietro Barabaschi called the component "a monument." He said the delivery would let machine assembly continue according to schedule.

Barabaschi listed the core tokamak components that are now all on site:

• toroidal field coils, poloidal field coils and correction coils
• central solenoid magnets
• vacuum vessel sectors
• thermal shield sets

The coils and the central solenoid are the machine's magnets. By ITER's definition, the core machine is the cryostat, all the superconducting magnets, and the vacuum vessel with its thermal shield. The cryostat is a large vacuum chamber that encloses the vessel and the magnets.

What is ITER's vacuum vessel?

The vacuum vessel is the sealed chamber where the fusion reactions will take place. ITER is a tokamak. That is a machine that uses magnetic fields to hold hot, charged gas called plasma inside a doughnut-shaped chamber. ITER describes the vessel as a double-walled steel container that also acts as a first safety barrier. Cooling water flows between the two walls to remove heat.

ITER gives these figures for the finished vessel:

• 19.4 meters across and 11.4 meters high
• about 5,200 metric tons, rising to 8,500 once the blanket and divertor are installed
• an interior volume of 1,400 cubic meters
• 44 openings, called ports, for heating, fueling, diagnostics and remote handling

The blanket and the divertor are parts that will sit inside the vessel. Blanket modules will line its inner surface. ITER says they will shield against the high-energy neutrons that fusion produces.

ITER says a larger chamber makes it easier to confine the plasma and produce significant fusion power. The plasma at the center of the vessel will fill 840 cubic meters.

Who built the nine sectors?

Europe made five sectors and South Korea made four. World Nuclear News reports that Korea was first assigned two. In 2016 it agreed to make two more that had been assigned to the European Union. Korea delivered its first sector in 2020. Its fourth and last reached the site on November 8, 2024.

All five European sectors arrived within the past two years, according to ITER and F4E. F4E worked with a consortium of three companies: Ansaldo Nucleare, Westinghouse and Walter Tosto. ITER says the European effort lasted more than 16 years. It drew on a supply chain of at least 15 companies.

F4E gives these figures for Europe's five sectors:

• more than 2 million hours of work
• 750 kilometers of weld beads in total
• four segments per sector, made in Monfalcone and at Walter Tosto in Chieti

F4E Director Marc Lachaise joined the ceremony remotely. ITER says he acknowledged the Korean agency, which shared lessons from its four sectors with the European teams.

What still has to happen before ITER runs?

Arriving on site is the first of several steps. Each sector is joined with thermal shield panels and two toroidal field coils of about 310 metric tons each. The result is called a sector module. It is then lowered into the tokamak pit, where the machine is being assembled.

ITER said on July 29, 2026 that it had installed the sixth of nine modules. By ITER's own account, that was almost six months ahead of schedule. The release does not say which schedule it means. The lift took 30 hours and moved a module of about 1,100 metric tons. ITER said then that it expected to place the final module by mid-2027. The earlier estimate was December 2027. Once all nine modules are in the pit, teams will join the sectors to complete the ring.

Another module, known as sector module 9, is scheduled to move to the pit in early December 2026. The American Nuclear Society's Nuclear Newswire reported that date on September 9.

Some parts needed repair along the way. Nuclear Newswire reported that microscopic stress-corrosion cracks were found in the vessel's thermal shield in 2021. A three-year repair project ended in July 2026. In July 2024, ITER named the Covid pandemic and repairs to key machine components as the major drivers of its delay.

The milestone also leaves out the parts that go inside the vessel. ITER says in-vessel components, plant systems and other equipment are still to come. Nuclear Newswire's report on the delivery made the same point.

When is ITER due to start operating?

ITER's published timeline, as read on October 8, 2026, includes these coming dates:

• 2033: cryostat closure
• 2034: start of research operation
• 2036: full magnetic energy
• 2039: start of deuterium-tritium operation

Deuterium and tritium are two forms of hydrogen. ITER calls their reaction the most efficient fusion reaction in a laboratory setting.

The dates come from a baseline the ITER Organization proposed in 2024. It was meant to replace a plan used as a reference since 2016. ITER's timeline page still describes it as a proposal. The page says the ITER Council, the project's governing body, approved the overall approach in 2024. ITER's report on the council's June 2026 meeting refers to the project's execution under Baseline 2024. Under the new plan, full magnetic energy comes three years later than in the 2016 plan. Deuterium-tritium operation comes four years later.

ITER is an experiment, not a power plant. It is designed to produce 500 megawatts of fusion power from 50 megawatts of heating power. It will not generate electricity. Its seven members are China, the European Union, India, Japan, Korea, Russia and the United States. Europe covers 45.6% of construction costs. The other six members cover 9.1% each.

For how ITER compares with private fusion projects, see Fusion Power: How Close Are We, Really?