Inside the ITER vacuum vessel, where the fusion reactions will occur, the ultra-high vacuum is comparable to that on the Moon. Conventional mechanical pumping alone is not sufficient to create such an extreme environment. Fortunately, a simple law of physics provides a solution for finalizing the initial mechanical pumping and achieving the required vacuum conditions prior to plasma operation. When a molecule or an atom encounters an extremely cold, spongy surface, it loses the best part of its energy and slows down to near immobility. This phenomenon is called "sorption" and its intensity is proportional to the temperature: the colder the surface, the more irresistible its holding power. In ITER, a set of cryogenic pumps, “cryopumps” in short, will trap the particles inside the microscopic mesh of their carbon-coated panels cooled to a few degrees above absolute zero (4 K or minus 269 °C).Procured by Europe, six torus cryopumps will be positioned around the tokamak’s vacuum vessel and another two attached to the cryostat. Five pumps have already been delivered; the other three are expected at ITER shortly. On Wednesday 14 January, ITER Director-General Pietro Barabaschi (centre) was given a tour of the installation by Alessandra Iannetti, of the ITER Vacuum System Project, and Robert Pearce, of the Plant and Process Engineering Division. The cryopumps servicing the 1,400 m³ ITER vacuum vessel will have a double mission: achieving ultra-high vacuum prior to the injection of the fusion fuels and—through the same sorption process—extracting the unburned fuel and helium “ash” generated by the deuterium-tritium fusion reaction.Cryopumps will operate in cycles, pumping when at cryogenic temperature and releasing their catch when “regenerated” at temperatures of up to 470 K (200 °C). Because they need to perform within an extremely wide range of temperatures, the cryopumps are among the most complex components of the ITER installation. The 8-tonne, 1.6-metre-in-diameter and 3.5-metre-long steel cylinders contain precision mechanics with moving parts that form the world's largest all-metal vacuum valve. More than twenty high-technology companies in Europe were involved in their manufacturing.Like all ITER components, the torus and cryostat cryopumps are subjected to a comprehensive series of factory acceptance tests before being shipped. This is not sufficient, however, to guarantee that they will perform as expected during actual tokamak operation. To remove all uncertainty and to prepare for ITER commissioning, a test facility was created last year inside the ITER cryoplant. The core of the test installation is a large cylindrical vacuum chamber, connected to the cryoplant's fluids distribution unit. When operational, bringing the ITER cryopumps to cryogenic temperatures will account for 25% of the cryoplant’s load. Already, the test installation will be the cryoplant’s “first client.” ITER Director-General Pietro Barabaschi (third from left) praised the quality and efficiency of the collaboration between the cryoplant team, the vacuum team and INOX-CVA—the ITER India contractor that built the cold valve box and some of the connecting cryolines and that participated in the equipment’s installation. On Wednesday 14 January, ITER Director-General Pietro Barabaschi paid a visit to the installation, which is now ready to enter the commissioning phase. “We will be testing the whole range of cryogenic processes,” explains Alessandra Iannetti, an engineer in the ITER Vacuum System Project. Testing will begin this month using “hot helium” at ambient temperature to demonstrate the performance of the cryopump’s mechanical components such as valves and interlocks. Then, as soon as the fluids from the cryoplant are available, temperature in the installation will be progressively brought down to 80 K (minus 193 °C) to test potential leakage and thermal losses, and eventually to cryopump operating temperature at 4 K.Once the cryopump functionalities are verified, the teams will “get into the actual science” of particle pumping, pump regeneration, unburned fuel and “ash” capture and release. Before eventually using hydrogen, different gases with a close molecular mass, such as helium and neon, will be used as substitutes to simulate the whole range of plasma operation scenarios.Operating the cryopump test facility will provide precious feedback for another, much larger installation: the magnet cold test facility that will start cold-testing the tokamak’s massive toroidal field coils1 by the end of this year.¹The facility will be located in the partially vacated Poloidal Field Coils Winding Facility. The dimension of its cryostat will also allow for the testing of the smallest of the ITER poloidal field coils, PF1 from Russia. 

Two days ago, an extra upending tool—which ITER recently ordered from Korea to speed up operations related to vacuum vessel sector repair and sector module assembly—began its month-long journey to ITER. The more than 100-tonne structure, manufactured under tight time constraints by Yujin Mechatronics, is more versatile than the one that has been in use at ITER for the past five years. Its configuration will facilitate the “flipping” of the vacuum vessel sectors being repaired in a horizontal position to allow access to their second side.With two upending tools available, one specializing in the handling of toroidal field coils and the newest in vacuum vessel sectors, the need for regular tool reconfiguration will be avoided which could amount to time savings in the range of weeks in the assembly process schedule. Another massive benefit: the transfer and temporary “parking” of a vacuum vessel sector in the tokamak assembly pit, initially envisaged for sector 8, is not needed anymore.The upending tool and its vacuum-vessel-dedicated lifting frames are expected at Fos-sur-Mer harbour in mid-March and could be operational, after mounting the two halves of the tool together, from mid-April.

Since last year, anyone at ITER can have access to an integrated 3D model that takes them from the highest-level view of the entire site, all the way down to a millimetre-level view of any component of the machine or plant. The new solution was developed by the ITER Design Office in collaboration with ITER IT. Every week, output is extracted from all CAD tools—around 20 terabytes of data in over 100,000 files—and converted to a common format on a high-performance server. The resulting integrated model is only a few gigabytes that can be downloaded to a standard laptop or workstation, where it can be viewed through Navisworks 3D Viewer, a software package used in many other large projects.One of the reasons the integrated model can be made so much smaller is that it only needs to be viewable, not editable. But according to Mickael Chabre, a design office infrastructure engineer, the model can also be enriched with the engineering properties of components. “For example, you can look for a specific valve and visualize it in its environment,” he says. “If you want to see the properties of the valve, meaning its nominal size, its safety class, and so on, that is possible thanks to the connection between Navisworks and the engineering database.”Prior to June 2024, it was possible to view a design model in the context of its environment through a software package called 3DLive. “But that required an advanced level of CAD knowledge and could not be connected to an external engineering database to enrich the model,” says Jean-Daniel Delaplagne, group leader in IT in charge of support of the CAD infrastructure and construction tools.Designers primarily use one of two CAD software platforms to develop 3D models—Dassault System’s Catia V5 for mechanical design, and Aveva’s E3D for plant design, which includes studies like piping, HVAC systems, structural supports and electrical components. Because each platform uses proprietary formats, before last June anybody wanting to view a model with its engineering attributes had to use the CAD system the model was developed on, which requires a license. That gets costly as the number of people viewing a design increases. And people who just want to view a model generally need training to use the complex tools intended for advanced design.The new platform is user-friendly and provides a view of the entire site (see the short video clip below). License costs for the Navisworks 3D Viewer are low and there is a free version for “basic users.” The desktop version is already available as a download, but IT now plans to integrate it within the ITER Collaboration Platform (ICP), as a web version that requires no additional software. This will make it easier to access. The technology made available in June meets a need that the project and the design offices identified a long time ago: a view of any part of the plant, available to everybody. The new tool allows engineers to see everything located around a system they are designing to make sure there are no clashes. It also provides construction teams with a 3D model of what they have to install and everything around it. Finally, the model can be used to prepare a site visit, allowing hosts to see where they will be taking visitors.These use cases are just the beginning. According to Delaplagne, a new solution is now being piloted to enhance design reviews using mixed reality. Engineers and project managers can wear Meta Quest headsets to view the 3D model remotely as if they were standing in the room, which will hopefully improve productivity.“The Design Office manages the 3D CAD software,” says Chabre. “But without help from IT, we could not have automated the extraction of the data coming from CAD software and merge it into a single platform.” While Navisworks is being used now, Chabre says that if a decision is made in the future to replace it with another solution, the input data is already available and can be pushed to the new platform.The integrated model, which currently provides an as-designed view of ITER, will be updated with as-built information to enable a whole new set of use cases. Scanning is already underway in some of the buildings to collect and catalog what has already been installed. “We use a laser scanning solution, Cintoo, to manage scans of the buildings, creating billions of points down to millimetre-level precision,” says Delaplagne. “This will allow people to compare as-designed and as-built. One can be superposed on the other to reveal the delta.”