At the speed of a person walking, reaching the ITER site from Berre-l’Étang, 70 kilometres away, takes approximately 16 hours. But if you are planning to travel only between around 10:30 p.m. and the wee hours of the following day, the journey would take the better part of five nights. Despite being equipped with an 800 HP power pack, the convoy that arrived at ITER in the early hours of Saturday 4 October could not move any faster. The “highly exceptional load” it transported was not the heaviest to have travelled the ITER itinerary, but it was the longest and, by a few dozen centimetres, the widest.The cryostat for ITER’s magnet cold test facility—into which some of the D-shaped toroidal field coils as well as PF1, the smallest of the ring-shaped poloidal field coils, will be inserted—is shaped like a giant sardine box. Measuring 22 metres in length and almost 11 metres in width for a total volume of 1,400 cubic metres, the component presented the convoy operators with unique challenges, which explain the exceptional duration of the transport. No ITER convoy until now has taken more than four nights to travel the ITER itinerary. Passing through villages, like here in the small town of Berre-l'Étang on the first leg of the journey, is one of the most challenging phases of the transport operation. Street lamps, road signs, and bus stop structures have to be temporarily dismantled prior to the convoy’s passage, and reinstalled immediately afterwards. The existence of such a component results directly from a “window of opportunity” that opened up in ITER’s plans for construction. As issues encountered with the vacuum vessel sectors and thermal shield piping interrupted the machine assembly sequence in 2022, it became apparent that toroidal field coils would remain accessible long enough to allow for the creation of a cold test facility and the testing of some of the coils—ideally at least one per supplier—at 4 K (minus 269 °C).It was no small feat that the whole cycle of designing the test bench and having the components manufactured, shipped and delivered was completed in 30 months. The contract for the largest piece of equipment—the customized cryostat that arrived last week—was signed in December 2023 with a Chinese consortium that includes the Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP), and Shanghai Electric Nuclear Power Equipment Co., Ltd. (SENPEC). The component was ready to ship in the summer of 2025. ITER director-general Pietro Barabaschi (right) was present in Berre to witness the departure of the convoy on Monday 29 September. He is seen here in a discussion with François Genevey, ITER Project Director at Global Logistics provider DAHER, and Julien Fribaud, head of convoy from transporter Capelle. Gendarmerie colonel Arnaud Estebe and his deputy are standing in the background. The 104-kilometre-long ITER itinerary is sized to accommodate the largest of the machine’s components. In 2018, a change in the transport strategy of PF6 (the second-smallest of the six poloidal field coils that encircle the vacuum vessel) had required that a narrow passage between two small cliffs, located between the Bridge of Mirabeau and the ITER site, be enlarged to allow the passage in June 2020 of the 10-metre wide component.The most recent ITER convoy carried an even wider load, but precise measurements by DAHER transport experts determined that because the magnet test facility cryostat sat higher on the transport trailer relative to the V profile of the gap between the cliffs, getting through this delicate passage would not be an issue. The total length of the trailer, however—slightly over 22 metres—would require driving exceedingly slowly. And even more streetlamps, road signs, gas pipeline beacons and bus stop structures would have to be temporarily dismantled prior to the convoy’s passage and reinstalled immediately afterwards.The 330-tonne component is now safely stored in the former Cryostat Workshop on site, where it will be equipped with reflective “super insulation” prior to its transfer to the magnet cold test facility where systems commissioning is ongoing. The first elements of the facility are now connected to the cryoplant and they have been operating at 4 K since last Friday.

Once a sector module is positioned inside the tokamak assembly pit, a lot of work remains to be done before it can be welded to its neighbours and form the toroidal volume where fusion reactions will be produced. One of the first activities, set to begin in the coming weeks on the sector modules that have already been installed—modules #6 and #7—consists of welding the in-vessel attachments, called “bosses,” that will host diagnostic system connections, cable looms and sensors.To that end, a set of four platforms has been installed inside of the 15-metre-tall modules. This “in-vessel staging” will provide manual access to all areas of the vacuum vessel inner wall. Some 1,200 bosses need to be welded to the interior surface of each module. The “in-vessel staging” is clearly visible in this image. The four platforms, including one at the lower, divertor level, will provide a safe working space from which all areas of the vacuum vessel inner wall are accessible. The platforms will also be used to finalize the connection between the thermal shield panels of the two sector modules which, for the moment, are not yet in contact. The connection, both mechanical and thermal, will be achieved by way of splice plates bolted onto the edge of the panels. Connecting two sets of sector module panels requires 124 splice plates, each between 10 and 15 centimetres wide. Principal pit construction manager Mathieu Demeyere lifts the plastic cover that protects the interface between the thermal shield panels of the two sector modules in the pit. The splice plates connecting them will fit onto the protruding bolts visible at the centre of the image. Welding the bosses and bolting the thermal shield panels will progress in parallel on the four “floors” of the in-vessel staging. 

The next generation of fusion experts is coming to ITER in November. About 150 PhD students from European universities, laboratories and institutes will gather at ITER from 4-6 November 2025 under the umbrella of FuseNet, the European fusion education network, for its annual PhD Event—an event that coincides this year with FuseNet’s fifteenth anniversary. During their three-day stay at ITER, the students will hear keynote talks about recent developments in the field of fusion energy and at ITER, join a round-table discussion about public-private partnerships in the field, and have a peek at the ITER tokamak in the making. The students will also share their own research—either as a poster presentation or in an oral presentation Pecha Kucha style. As is customary with these meet-and-greet events, students will also have many opportunities to network with fellow researchers. Click to read more about the event or to download the program. (The event is fully booked; no registration is possible.)