Underneath the concrete slab that supports the Tokamak Complex is a vast, dimly lit space whose only features are squat, pillar-like structures called 'plinths.' Sandwiched between the top of the pillars and the slab above, flexible seismic pads ensure that in the event of an earthquake, the integrity of the building will be protected from sudden and strong horizontal accelerations. Out of a total of 493 plinths, 90 are arranged in a circle underneath the tokamak 'crown' and the bioshield wall, which together will support the 23,000-tonne machine and absorb the brunt of the horizontal and rotational forces during operation. Only one is required directly under the centre of the machine below the central solenoid magnet. For the duration of machine assembly, however, this central point is subject to extra pressure due to the configuration of assembly tooling and requires extra support. A temporary propping system is already in place. A concrete 'crown' under the machine, radially anchored every 20 degrees in the bioshield, will support the combined mass of the vacuum vessel, magnets and cryostat (23,000 tonnes) and direct loads outward to the exceptionally thick and strong bioshield. During the assembly phase, however, the distribution of mass is quite different—with the dead weight of the installed components supported by two temporary assembly tools: the central column, anchored in the concrete slab of the Tokamak Building, and the radial beams supported between the central column and the bioshield wall. In order to compensate the pressure that the central column exerts on the central seismic plinth, a temporary propping system was installed in December 2021 at the very centre of the seismic support arrangement. This passive device will stay in place until the completion of tokamak assembly activities. Precisely positioned under the central column, below the basemat slab, 16 massive propping elements stand in a close circle around the lone central plinth. Each of the elements comprises a powerful hydraulic jack sitting on a metal stool and equipped with a rotational head and sliding bearings. 'In case of a seismic event during the assembly phase, it is essential that the propping system does not interfere with the building's behaviour,' explains Armand Gjoklaj, a nuclear engineer in ITER Buildings & Civil Works Section. 'The jacks' rotational head and the horizontal sliding bearings' Teflon sheets contribute to the building's freedom of movement.' With only one sector module installed and weighing on the central column for the moment, the portion of the present load transferred to the temporary propping system is on the order of 350 tonnes—way below its nominal capacity of 8,000 tonnes. (The vertical load from the central column in case of seismic event is conservatively estimated at 5,600 tonnes.) The system capacity is defined to also limit the relative vertical displacements of the central seismic pad (on the order of one millimetre), which are monitored in real time by an array of gauges and load cells. As more modules and other components are installed in the Tokamak assembly pit, the load transferred to the propping system will increase until installation is complete and the central column and radial beams are removed. At that time, the crown and bioshield wall will take over the heavy task of supporting the machine.

As part of a continuing commitment to improve quality culture both at the ITER Organization and at the Domestic Agencies, the Vacuum Delivery & Installation Section delivered a training session on vacuum standards and quality to 30 delegates on 31 May 2023. The one-day session at ITER comprised lectures on vacuum quality, qualification, material requirements and leak testing. In addition, a practical session on leak detection techniques was held in the B99 vacuum laboratory on site. 'Quality in vacuum is key to the success of a fusion device and an overall improvement in quality is required to minimize the risks of building a machine that does not meet the project objectives,' explains Section Leader Robert Pearce. 'If unmitigated, ITER may expect a 100 fold increase in vacuum-related problems when compared to other operating tokamaks,' he added. Sharing the message that vacuum is a critical issue with technical responsible officers, quality assurance specialists, and resident inspectors working at ITER and in the Domestic Agencies creates the opportunity to raise awareness on potential issues and promote good practices in the organizations and among suppliers. One participant—Guim Pallas, technical responsible officer for leak localization at the European Domestic Agency--had this to say after last month's session: 'I would strongly recommend the training to everyone working with or around vacuum.' 'We plan to hold the training session twice a year and interested parties should contact me to register their interest. Course content can be tailored to the delegates' interests,' says training organizer Liam Worth (liam.worth@iter.org). The training material presented can be provided on request. You can download the ITER Vacuum Handbook on this ITER webpage.

Registration for the 28th International Conference on Magnet Technology (MT-28) is open on line through 5 September 2023 on the conference website.See all fee information here, including reductions for retired participants, students and one-day attendees. The registration fee includes access to the exhibition, all technical sessions, all poster sessions, and receptions.The conference will take place in Aix-en-Provence, France (only 30 minutes from the ITER site) from 10 to 15 September 2023. ITER site visits will be organized.To register to MT-28, see this link.

From a survey of 26 private fusion companies and 34 supplier companies, the Fusion Industry Association—a US-registered non-profit independent trade association for the acceleration of the arrival of fusion power—predicts a huge growth in demand for fusion suppliers over the coming years.  Its report The Fusion Industry Supply Chain: Opportunities and Challenges calculates that from USD $500 million in 2022, the fusion supply chain is set to increase to over USD 7 billion by the time companies build their first-of-a-kind power plants. When the fusion industry reaches maturity, the supply chain is predicted to be worth trillions of dollars. Seventy percent of fusion companies surveyed, however, said their suppliers see building the capacity to meet future demand as too risky without committed orders. 'It is clear more long-term certainty is needed—through a mix of finance, regulation, risk-sharing mechanisms, and more communication—so suppliers are prepared to scale ahead of industry need." Read the full report on the Fusion Industry Association website.