The 38th ITER Council Meeting successfully concluded in Saint-Paul-lez-Durance, France, noting strong project execution. The governing body reviewed milestones across construction, assembly, and licensing to advance the world’s largest magnetic confinement plasma physics experiment.
ITER is a first-of-a-kind global collaboration. As the host, Europe contributes almost half of the costs of its construction (45.6%), while the other six members of this joint international venture (China, India, Japan, South Korea, Russia and the US), contribute equally for the remaining expenses (9.1% each). However, in practice, the members deliver little monetary contribution to the project, instead providing ‘in-kind’ contributions of components, systems or buildings.
The goal of ITER is to operate at 500 MW (for at least 400 seconds continuously) with 50 MW of plasma heating power input. Some 33 nations are collaborating in the construction of ITER, which began in 2010, many of them through their Domestic Agencies (DAs).
Construction began in 2010 and the original 2018 first plasma target date was put back to 2025 by the ITER council in 2016. In June 2024, a revamped project plan was announced which aims for “a scientifically and technically robust initial phase of operations, including deuterium-deuterium fusion operation in 2035 followed by full magnetic energy and plasma current operation”. The 37th meeting of the ITER Council in December 2025 reported significant progress.
The 38th Council noted that assembly progress is marked by key actions like the final alignment of central solenoid modules and the positioning of vacuum vessel sectors. Crucial plant systems are entering testing phases, highlighted by successful helium liquefaction inside the ITER Cryoplant. France’s Authority for Nuclear Safety and Radiation Protection (ASNR – L’Autorité de Sûreté Nucléaire et de Radioprotection) agreed to exclude the ITER vacuum vessel from specific European Pressure Equipment Directive legislation. This decision will improve cost and schedule efficiencies. The Council praised the Private Sector Fusion Engagement (PSFE) project for actively transferring technical expertise and knowledge to emerging private fusion firms.
The Council Meeting confirmed that the project is successfully operating under Baseline 2024, which provides an updated framework to manage past pandemic and technical delays. The current framework establishes clear, technically sound milestones designed to streamline assembly and transparently communicate development progress.
Major physical milestones are moving ahead swiftly. The fifth sector module was successfully lowered into place in May 2026, and the final lifting and positioning of the sixth central solenoid module was finished in June 2026. The timeline is heavily supported by the newly operational Magnet Cold Test Facility, allowing components to undergo rigorous integration testing before being placed on the critical assembly path.
The timeline repairs for the ITER project were forced by severe quality control failures and technical defects discovered across two primary first-of-a-kind components: the vacuum vessel thermal shields and the vacuum vessel sector modules. The thermal shield piping showed stress corrosion. Severe cracking and helium leaks were detected in the cooling fluid pipes. High stress caused by bending and welding the pipes was worsened by a slow chemical reaction. Chlorine residues left behind during manufacturing triggered stress corrosion cracking. Engineers had to strip and replace roughly 23 kilometres of cooling pipes across all vacuum vessel and cryostat thermal shield panels.
Vacuum vessel sectors showed dimensional non-conformities. Fabricated six-story-tall steel sectors arrived with significant dimensional warp. Gaps and misalignments of up to two centimetres were found along the welding bevels where the pieces must connect. The massive component deformed out of shape due to shrinkage stresses caused during on-site and factory welding.
Technicians had to deploy a meticulous, multi-step process combining manual metal build-up, precision robotic machining, and extensive ultrasound testing to reshape the edges back to millimetre-level tolerances. Because one of these defective vessel modules had already been lowered into the machine pit, assembly had to stop completely. Teams had to lift and disassemble the entire 440-tonne component to conduct repairs in an on-site workshop.
The recent regulatory shift granted by ASNR directly protects the timeline from additional structural disruptions. ASNR formally excluded ITER’s vacuum vessel from the rigid scope of French laws implementing the European Pressure Equipment Directive. The vacuum vessel remains classified as a Protection Important Component (PIC) subject to full nuclear safety oversight. However, technical requirements and monitoring criteria are being adjusted specifically to address fusion, rather than traditional fission, characteristics. This “fit-for-purpose” approach avoids redundant administrative procedures and manufacturing constraints. Transitioning away from general pressure equipment directives removes bottlenecks, directly preventing cost overruns and building delays.
The component defects, combined with inflation and global supply chain pressures, triggered a massive budget increase. The European Court of Auditors confirmed that the new baselines will require an additional €4.2bn ($47.8bn) just from the European Union, which covers roughly 45% of the project’s overall construction costs.
To avoid future component failure, ITER leadership scrapped the original plan to use a beryllium first wall, moving to a tungsten design. This change added immense immediate material and engineering costs but will ultimately save money by preventing the wall from degrading under early high-power tests.
The original target for a low-power “first plasma” in 2025 was completely abandoned because it would have required running a machine with known, un-repaired interior defects. Instead, ITER transitioned to a “Start of Research Operations” philosophy with a drastically shifted timeline under Baseline 2024. Substantial plasma research is now set for 2034 with full scale operation in 2039. By pushing back the timeline, engineers gained the necessary time to carefully align the vacuum vessel modules in the pit without rushing the high-precision robotic repairs.
