In order to reach clients inside the Tokamak Building, cooling fluids produced by the ITER cryoplant flow through many kilometres of highly sophisticated piping called cryolines. Departing from and returning to the cryoplant, the cryolines must pass over an industrial bridge more than 10 metres above the boulevard below. The installation of this double set of cryolines in the cryobridge—the largest measuring one metre in diameter—began in February. Earlier this month the teams successfully performed one of the most challenging operations of the whole installation process: the precise positioning of a 9-tonne cryoline spool designed to decouple displacements between the cryobridge and the Tokamak Building in case of a seismic event. Upon exiting the cryoplant's termination cold box, which acts as a dispatcher for the different cooling fluids, two sets of cryolines leave the facility over a massive industrial bridge that starts by spanning the 75-metre distance between the cryoplant and the Assembly Hall, and then takes a 90-degree turn left to run along the building for another 50 metres before reaching the Tokamak Building at L3 level. Along with the steel bellows placed at regular intervals along both the cryolines' inner pipes and outer jackets to compensate for metal contraction due to the flow of intensely cold fluids, the decoupling spools are dimensioned to withstand the displacements that an SL-2 earthquake would cause—an event predicted to occur once every 10,000 years. "In case of a seismic event, even of a lower intensity than SL-2, the Tokamak Building, the Assembly Hall (to which the cryobridge is attached), and the cryobridge itself would each respond in a different manner," explains Lahcene Benkheira, the ITER cryogenic systems responsible officer. "Without a decoupling device, the cryoline network could rupture which—in a nuclear installation—would amount to a loss of confinement." There will be a total of six such decoupling spools in the cryobridge; three of them have already been installed. Measuring between 6 and 9 metres in length and weighing between 2.2 and 9 tonnes, the cryoline spools need to be perfectly aligned before welding operations can begin. Sometimes, a bit of pushing and pulling is necessary... The difference in the response to a seismic event stems from structural properties: the Tokamak Building is part of a 400,000-tonne reinforced concrete nuclear building (the Tokamak Complex) that sits on anti-seismic system that allows an important amplitude in lateral displacement; the Assembly Hall is a steel structure with a small degree of flexibility, as is the cryobridge attached to it. In order to decouple and absorb the specific response of these different structures, the decoupling spools are equipped with lateral and transversal gimbles that act as ball joints, a bit like the hip joint in the human body. Another major element in ensuring the integrity of the cryoline network is the quality of the welding for the 4 or 5 process pipes within every spool. One of the first challenges lies in aligning these massive components that measure between 6 and 9 metres in length and weigh between 2.2 and 9 tonnes. Once the inevitable offsets are compensated (sometimes by workers pushing and pulling) and the protruding process pipes at each end of the spools are almost in contact, the welders, duly qualified, can proceed. The task is difficult, the space constricted, the body contortions sometimes painful but the work gets done, millimetre after millimetre, for a total length of several kilometres. The welders' task is difficult, the space constricted, the body contortions sometimes painful but the work gets done, millimetre after millimetre, for a total length of several kilometres. The installation of the cryoline spools along the cryobridge leg parallel to the Assembly Hall is expected to be completed by the end of the summer, while the activities along the perpendicular leg leading to the cryoplant should be finalized by the end of the year. All in all, the cryoline network installation is now approximately 70 percent completed.

The serial production of ITER's powerful torus and cryostat cryopumps is progressing at Research Instruments, Germany, on behalf of the European Domestic Agency Fusion for Energy. Last week, the first production unit was cleared for shipment to ITER. The first ITER cryopump passed all final factory acceptance tests at Research Instruments (RI), Germany, last week, marking a major milestone in the procurement program for these one-of-a-kind components that were developed through the close collaboration of experts at ITER, Fusion for Energy and European industry.  "This achievement paves the way for delivery of the first cryopump to ITER by the end of the month and seven more by the end of the year," says Robert Pearce, ITER Vacuum System Project Leader. With a volume of nearly 1,400 m³ and 8,500 m³ respectively, the ITER vacuum vessel and cryostat range among the largest vacuum systems ever built. To create the very specific vacuum conditions that ITER requires, cryopumps—which "capture" unwanted particles by trapping them on extremely cold surfaces—are indispensable to finalizing the initial pumping done by mechanical devices. ITER will rely on six torus cryopumps to maintain ultra-high vacuum inside the ITER vacuum vessel during operation and to create low density—about one million times lower than the density of air. Two other cryopumps will provide the insulating vacuum in the cryostat that allow the superconducting magnets to remain cold. All eight are under the procurement responsibility of the European Domestic Agency Fusion for Energy. Research and prototyping have been underway for years; since 2018 the build-to-print procurement package has been in the hands of industry after the delivery of a pre-production cryopump unit for testing and the signature of the Torus and Cryostat Cryopump Procurement Arrangement.  

Take out your smart phone and search your favourite news site for "nuclear fusion" or "fusion energy." On any given day, you will find articles discussing breakthroughs or innovative approaches to fusion. Dig deeper: you will find that the fusion projects under discussion are a mix of public and private initiatives—unique, because both sectors are still in the R&D phase. Not infrequently, you will find the current state of fusion characterized as a "competition" between public enterprises such as ITER and emerging private sector initiatives. But is this the reality? Is it true that the public and private fusion sectors are in a race, and that the winner will make all others obsolete? Or—to ask a better question—if all parts of the fusion community share a common goal, what would be the ideal relationship between the public and private sector? To answer that question, next week ITER will launch an unprecedented workshop featuring the leaders of these private sector initiatives. More than 350 fusion scientists and engineers—including representatives from more than 30 private sector fusion start-ups—will converge on the ITER site to present their achievements, their challenges, and their ideas on how ITER can help them. ITER, largely, will take the role of listener, offering worksite tours, discussions with experts, and brainstorming sessions on how to optimize collaboration while remaining focused on ITER's central mission. The workshop is a first step, responding to a request from the ITER Council last November. For the Council to call for engagement with private sector fusion initiatives is, in itself, a recognition of the changing fusion R&D landscape. The nature and scope of that engagement is still to be determined. Optimally, the goal would be to take advantage of the complementarity in public and private initiatives. ITER remains a sort of convergent national lab for all its Members, designed to enable repeatable experiments and long-term testing at industrial scale. By contrast, the private sector can offer smaller scale, more agile initiatives—leading to enabling technologies (e.g., better magnets and control systems), new physics, innovative materials, and concepts that involve a higher risk of failure. Over time, the ambition is for this collaboration to lead to a "joint public-private narrative"—and, more importantly, a cross-sector approach to fusion innovation—in which the breakdown of information silos and the consolidation of knowledge can drive success.

The 30th Meeting of the ITER Council Science and Technology Advisory Committee (STAC-30) took place at ITER Headquarters from 13 to 16 May. The Science and Technology Advisory Committee (STAC) advises the ITER Council on science and technology issues that arise during the course of ITER construction and operation. In its last meeting in September 2023, the STAC reviewed the new plans for construction and operation proposed by the ITER Organization and Member's Domestic Agencies. It supported the change in blanket first wall armour material (from beryllium to tungsten) and recommended adopting the proposed outline operational plan as a basis for the further articulation of the Updated Baseline. This month, after the further consolidation of the ITER Research Plan, including the input of experts, the STAC gathered to review progress and strategy. A full report will be made to the ITER Council, which will meet on site at ITER in June. This week, the ITER Council Management Advisory Committee (MAC) also convenes at ITER Headquarters. Its role is to advise the ITER Council on strategic management issues.

Last week, in the framework of the International Conference on Plasma-Surface Interaction (PSI-26) hosted in Marseille, a lunch event organized by Women in Fusion on "Creating an Inclusive Fusion Workforce" was attended by more than 100 people. Women in Fusion (WiF) is a global platform advocating for women and women's organizations active in the fusion community (public and private sectors as well as academia) all around the globe. The group seeks to inspire and support women in the fusion field by highlighting their roles in the field, promoting their leadership, and encouraging recognition of their contributions. The conference also opened with a keynote on the importance of gender diversity and inclusion in the fusion community, delivered by Laurence Piketty (Deputy Director General of the French Alternative Energies and Atomic Energy Commission, CEA) and ITER Director-General Pietro Barabaschi.

Sven Korving, a PhD student researching nuclear fusion at the Eindhoven University of Technology in collaboration with the ITER Science Division, had his publications selected not once, but twice for the Editor's Pick of the journal Physics of Plasmas. The journal called the research "noteworthy, novel, timely, interesting, and important." In his latest paper, dated this month, Korving predicts the transport of impurities in plasmas where instabilities are suppressed by external 3D magnetic fields. His research stands out for the contrast with papers that focus on isolating a single phenomenon, while he develops models to simultaneously and consistently simulate multiple phenomena, interconnected and coupled with each other. The Eindhoven University of Technology's Department of Applied Physics and Science Education celebrated his achievements in a LinkedIn post, found here. More information on Sven's research can be found here. Korving, S. Q., Huijsmans, G. T. A., Park, J.-S., & Loarte, A. (2023, April 5). Development of the neutral model in the nonlinear MHD Code JOREK: Application to E × B drifts in ITER PFPO-1 plasmas. AIP Publishing. https://pubs.aip.org/aip/pop/article/30/4/042509/2882953/Development-of-the-neutral-model-in-the-nonlinear Korving, S. Q., Mitterauer, V., Huijsmans, G. T. A., Loarte, A., & Hoelzl, M. (2024b, May 8). Simulation of neoclassical heavy impurity transport in ASDEX Upgrade with applied 3D magnetic fields using the nonlinear MHD code JOREK. AIP Publishing. https://pubs.aip.org/aip/pop/article/31/5/052504/3290641/Simulation-of-neoclassical-heavy-impurity --Three dimensional image of the tungsten density at the plasma edge of ASDEX Upgrade modelled by the JOREK code when 3D magnetic fields are applied for ELM control, as foreseen in ITER.