The ASDEX Upgrade tokamak in Germany has been helping to establish the scientific basis for the optimization of the tokamak approach to fusion energy since 1991. Last month, as the ASDEX Upgrade team met to plan out its next plasma campaigns, ITER was invited to highlight key research needs for operating ITER with a tungsten first wall, particularly in the area of plasma-wall interactions. The ongoing ITER re-baselining exercise concerns not just modifications to plant and hardware to be installed in and around the tokamak, but also a reconfiguration of the ITER Research Plan, the main document which guides the commissioning and experimental exploitation of the device once construction is complete. An important component of the re-baseline, the switch from beryllium to tungsten for the blanket first wall armour, is also the most challenging modification in terms of impact on the Research Plan. A higher tungsten source means higher potential contamination of the plasma core and impact on the fusion power output. It can also be an obstacle to reliable plasma start-up which, in most tokamaks including ITER, is performed by growing the plasma in a configuration which directly contacts the main chamber walls. In recent years, several medium-sized research tokamaks in the ITER Member facilities have been operating with majority tungsten plasma-facing components, improving confidence that the ITER Organization proposal to modify the ITER wall material is a manageable risk. Nevertheless, some aspects require further experiments and modelling to be more confident in the extrapolation to the ITER scale. It was in this spirit that the Institute of Plasma Physics, Chinese Academy of Sciences, responded to a call from the ITER Organization in October 2023 for support in addressing some of these issues, offering to place the EAST tokamak at the service of ITER for what turned out to be a very successful multi-week plasma campaign at the beginning of 2024. They were not the only ones; teams at the full-tungsten devices WEST (CEA/IRFM Cadarache, France) and ASDEX-Upgrade (Max Planck Institute for Plasma Physics (IPP), Garching, Germany) also engaged. Some dedicated experiments are underway at WEST in the current plasma campaign. Participants in the "monasterial" gathering. The ITER Organization was invited to attend the first two days of a dedicated week-long retreat (18-22 March) of an important contingent of the ASDEX Upgrade physics team looking ahead to new plasma campaigns. The ASDEX Upgrade facility, on the other hand, is presently nearing the end of a long shutdown for major upgrades to the tokamak, but that does not mean that plans are not being made to support the ITER re-baseline. Following some discussions in late 2023 with experimental program managers, the ITER Organization was invited to attend the first two days of a dedicated week-long retreat (18-22 March) of an important contingent of the ASDEX Upgrade physics team looking ahead to the new plasma campaigns. We were also generously given the opportunity of delivering the opening presentation to highlight key issues requiring further study for ITER operation with tungsten, particularly in the area of plasma-wall interactions.This wasn't just any ordinary meeting, however. Instead of sitting together in their institute for these discussions, the group convened at the magnificent Kloster Seeon, located on Lake Klostersee, one of the smaller lakes to the north of Lake Chiemsee about 90 minutes drive south east of Munich centre. The site of a former Benedictine monastery, and a self-contained, captive environment, it provides a perfect setting for productive scientific discussion and exchange. Exchange that was not limited to the day time meeting itself, but which continued into the evenings in typical Bavarian fashion.Gathered at the retreat were members of the IPP team forming what is known internally as the E2/E2M departments, comprising a wealth of experimental and simulation expertise ranging from the H-mode pedestal in the confined plasma region all the way across the cooler peripheral plasma to the bounding surfaces where plasma meets materials. Very productive, dedicated discussions followed the ITER presentation, with some important conclusions reached as to how forthcoming ASDEX Upgrade experiments and plasma materials interaction studies can best address the outstanding ITER questions in this area. The most pressing issues where IPP can make a very significant contribution concern specific tests of the plasma chemical vapour deposition process known as boronization (a wall conditioning technique widely deployed on research tokamaks, and which has been introduced as part of the ITER re-baseline to improve plasma start-up with an all-tungsten wall); the detailed characterization of plasma start-up on tungsten; the impact of a tungsten wall on H-mode performance and the erosion, redeposition and fuel uptake of boron layers. Several of these same issues are also being addressed on WEST and EAST, but in different ways dependent on the specific capabilities of each tokamak. Only by combining results from many sources and using them to benchmark and validate plasma simulation tools, can confidence grow that extrapolations being made for ITER are sound. It has always been so in fusion research and development. The group convened at the magnificent Kloster Seeon located on Lake Klostersee, about 90 minutes southeast of Munich by car. (Photo Richard Pitts) This "monasterial" gathering was not a meeting designed to make detailed plans for the ASDEX Upgrade experimental campaigns—the team will formulate those in the coming months—but to discuss which of the outstanding issues of importance for ITER regarding living with tungsten can be addressed efficiently, on a reasonable timescale, and within the constraints of a program with a great many other research topics on the menu. The ITER Organization looks forward to the upcoming experiments and would like to thank the meeting organizers again for their hospitality and for the opportunity to be part of the discussions.  

"Is ITER the 'star of science' whose creation has been made possible by humankind's sophisticated mastery of the laws of nature and the powers of technology? Or is it only the result of a scientific marketing operation supported by a community of researchers who managed to convince policymakers that they hold the keys to our energy future? What is ITER in the end? A revolutionary programme likely to save our civilisation or yet another expensive project aimed at impressing politicians and industrialists?" These questions, drawn from the introduction to ITER: The Giant Fusion Reactor by Michel Claessens, frame the perspective from which he creates his narrative: part cheerleader, part skeptic. ITER: the Giant Fusion Reactor presents ITER as the largest scientific collaboration of all time. Yet rather than taking a purely scientific angle, Claessens presents a narrative that is part fusion science and technology, part history, with a distinct emphasis on the human ambitions and quirks that give the project its character. The history of ITER, including both the political differences and the technological challenges that needed to be overcome to bring the project into being, is well researched. As a former Head of Communication at ITER, Claessens' own encounters with many key players help to lend the narrative a personal touch. The first edition of the book was published in mid-2019. The four years that followed were eventful for ITER: the advent of the Covid-19 pandemic; the coincident arrival of the first mega-components—gigantic magnets, the first pieces of the cryostat, and the first vacuum vessel sectors; the start of machine assembly; challenges in gaining regulatory approval for key project milestones; the discovery of component defects requiring repairs; the passing of Director-General Bernard Bigot followed by an intensive search and the appointment of Pietro Barabaschi as the new Director-General in October 2022; and the subsequent effort to reform the project and work toward an updated cost and schedule baseline. Given the significance of these events, it is no wonder that Claessens felt the need for a revision. Yet the second edition is more than just an update; it also takes a shift in tone, largely for the positive. After leaving the ITER Organization in 2015, Claessens also worked for Fusion for Energy, ITER's European Domestic Agency, and for the European Commission Energy Directorate in Brussels. His experiences in all three organizations, combined with his continued observation of ITER and contact with others in the project, led him to become a vocal critic and eventually a self-described whistleblower, in some cases questioning the integrity of ITER officials and the correctness of their decisions. This perspective gave a darker quality to some of Claessens' accounts, but also added intrigue and a sharply personal tone. With the new edition, including three additional chapters, Claessens sees "much improved information transparency" since the arrival of Director-General Barabaschi, particularly in relation to the frequent candid updates on ITER technology challenges and associated repairs. The tone of the new edition is largely positive, making clear that, however critical he may at times be, Claessens genuinely wants the ITER mission to succeed. The ITER project is, above all, a human endeavour, its complexity derived not only from massive components and precisely engineered structures, but also from relationships between individuals. For readers seeking a solid historical account and a unique perspective from a writer who has lived both inside and outside the project, ITER: the Giant Fusion Reactor offers an absorbing read. Claessens does not shy away from controversy, which means not everyone will agree with his perspective or his conclusions; but that does not detract from making his work an engaging narrative.

In October 2014, close to ten years ago, five giant cranes were installed on and around the Tokamak Complex basemat slab. As work progressed to erect the Complex and further lift capacity was required, other cranes were added and strategically positioned to serve the different work areas on the ITER platform. At the peak of construction activity in 2016-2018 a total of nine cranes were operating, with "heights under the hook" ranging from 56 to 84 metres and lift capacities of 20 to 40 tonnes. Crane C2, which was dismantled last week, was one of the original five, a workhorse that handled some of the heaviest loads during the construction and equipping of the Tokamak Building. Operated by the VFR Consortium, crane C2 was particularly tall (84 metres) and stood on a sturdy lower mast (4 x 4 metres) that reinforced its resistance to the gusts of wind that can be quite violent in Provence. One of the crane's key missions—and one that determined the choice of this specific model in the manufacturer's catalogue—was to introduce into the Tokamak Building, via the cargo lift shaft, 46 thirty-tonne nuclear doors to close off the port cells around the tokamak. (The nuclear doors weighed 30 tonnes as they were delivered; once filled with concrete and installed inside the Tokamak Building they weighed approximately 50 tonnes.) The handling and delivery of the nuclear doors also determined the crane's positioning in the Hot Cell excavation area, facing the cargo lift shaft.For most of its decade-long tenure, crane C2 operated on a two-shift basis, 16 hours a day. As worksite activity intensified, the workday extended to 24 hours in three continuous shifts. "Crane C2 demonstrated exceptional performance and durability," says VFR Project Director Aurélien Gayrard-Bouzereau. "Thanks to proper maintenance and to the highly qualified personnel who operated it, the crane served the ITER Project well beyond our initial expectations. Over 10 years of intense activity, no accident or major lifting incident ever occurred which is truly remarkable." Crane C2 demonstrated exceptional performance and durability and served the ITER Project well beyond initial expectations. Last week, a mobile telescopic crane with a lifting capacity of 450 tonnes was installed in the vicinity of crane C2 for the dismantling operation. Delayed a few days because of windy conditions, the crane's cables, 26-tonne counterweight, jib, motors, winches, counterjib, pinnacle, cabin and mast were finally successively disassembled between 2 and 4 April. All in all, the operation required 30 lifts and 25 trailers to evacuate the crane elements from the Hot Cell area.With civil works in the Tokamak Complex now finalized, two other cranes, C3 and C18, are set to be dismantled in the coming weeks. A familiar landscape, marked by the cranes' towering presence, will be gone. But only temporarily as other massive works, such as Hot Cell construction, will be launched in the coming years.

In the sixth installment of ITER Japan's manga series on the project, our hero Taiyô Tenno joins veteran staff member Mirai Mitsuhashi on a visit to the QST* R&D facility for the ITER divertor. Researchers there have developed a full-scale prototype for the outer vertical target, one of components of the divertor that will have to withstand the most intense heat load. By going back in time, Mirai reviews the incredible challenge that was posed to industry and the years of development  that culminated in the successful high heat flux testing of the full-scale prototype.  Travel along with Mirai and Taiyô by downloading Volume 6 of "ITER: A Small Sun on Earth" (divertor) from the ITER Japan website or directly from the ITER Publications gallery (comics). *QST = Japan's National Institutes for Quantum Science and Technology