They are the jewels of the concrete crown that will support the combined mass of the Tokamak and its surrounding cryostat: 18 perfectly polished, chrome-plated spherical bearings, each weighing approximately 5 tonnes. The 18 cryostat support bearings will act like ball-and-socket joints to allow the smooth transfer of the tremendous forces that will be exerted on the machine in all types of situations—normal operations, vertical displacement events or even an earthquake.   Following the production and validation of a series of models (one-fourth, one-half and actual size) the ITER contractor FPC-Nuvia launched the manufacturing process for the actual bearings in January. Twenty bearings will be produced, 18 to be inserted into the supporting crown and two spares.   Late in March, Laurent Patisson and Armand Gjoklaj of the ITER Building & Civil Works Section took a trip to Montebello, near Padua, Italy, where FPC-Nuvia is assembling the first cryostat bearings of the series.   The mission, on behalf of the Buildings, Infrastructure and Power Supplies Project Team BIPS, was to "witness" and validate the assembly process of the different elements that make up a bearing.   The parts making up the ball of the bearing (the semi-spherical "lens") and the socket (lower and upper backing plates, sliding material) are precisely assembled before being tested in a powerful press tool specifically designed for ITER's needs.   The different parts of the bearings are pre-assembled before getting "squeezed" by a powerful press tool. The first results have shown that bearings withstand the pressure as required, without compressing more than 2 mm. The press will apply an axial force of close to 22 meganewtons (approximately 2,500 tonnes) to the bearing, representative of the actual load the Tokamak would exert.   "Under that tremendous pressure, the 750-millimetre-high bearing must not compress more than two millimetres. This is very difficult to achieve but the first series bearings passed the test," explains Gjoklaj.   The assembly process and procedure was deemed satisfactory by the two BIPS witnesses—with "a little fine-tuning here and a bit of optimizing there ..."   Production of the cryostat support bearings should be completed by March 2018, marking an important ITER Council milestone.   Meanwhile, in the Tokamak Building, work is ongoing to prepare for the construction of the crown beginning in early 2018. As a fastening system for the bearings, a steel transition piece will be half embedded in the concrete crown during the first phase of pouring.   Then, a high-strength top plate (3.5 tonnes of steel) will be positioned on the transition piece to receive the bearings with a mechanical blocking mechanism worthy of a Swiss watch. Permitted tolerances for the different elements of the fastening system will be less the 2 mm.

With the recent addition of the Ukraine's Kharkov Institute for Physics and Technology (KIPT), the EUROfusion consortium now encompasses 30 European fusion laboratories. As its governing body—the General Assembly—convened last week at the Château de Cadarache, Newsline sat with Jérôme Pamela, General Assembly chair and former director of JET (1999-2006), EFDA (2006-2009) and Agence Iter France (2010-2016). How would you characterize the main missions of EUROfusion?   EUROfusion, which in 2014 succeeded the European Fusion Development Agreement (EFDA), is responsible for coordinating the activities of the European fusion laboratories and institutions involved in fusion research and development. The long-term objectives are defined in the Fusion Roadmap, which aims at delivering electricity from fusion.   Within this broad mission, the consortium has two main objectives: one is to prepare the European laboratories to participate in the scientific program of ITER; the other is to design the facility that will come after ITER—the pre-industrial demonstrator DEMO—for which pre-conceptual studies are presently ongoing.   Regarding the first of these two objectives, what is in your view the "added value" provided by EUROfusion?   Unquestionably, it is the shared utilization of selected installations and facilities such as JET (UK), ASDEX Upgrade (Germany), the variable configuration tokamak TCV (Switzerland), MAST-U (UK), WEST (France) ... and a few others. What is also important is that the EUROfusion research programs are established in common and implemented by joint experimental teams from the different participating labs and institutions. In my view this is an excellent example of what Europe can do—make the best of the specificities of existing fusion installations, work together and avoid duplication in fusion research.   "A unique pool of expertise" By Bernard Bigot, Director-General, ITER Organization There are several reasons as to why EUROfusion is important for ITER. The first is the opportunity for the ITER Organization and the seven ITER Domestic Agencies to have a single point of contact for interacting with 30 European research organizations and universities on strategic issues of common interest for the development of fusion science and technology. The second is the unique pool of expertise, accumulated knowledge and high-quality equipment that ITER can call on to contribute to the design, development, manufacturing and assembly of the ITER components both now, in the present construction phase, and later, in the operation phase (which we have already started to prepare). We expect that some of the most talented scientists, engineers, technicians and operators trained and working as part of the EUROfusion consortium will be ready to join the ITER Organization when the project needs them. The third reason is the invaluable contribution of EUROfusion consortium labs to the advancement of plasma physics, which helps to prepare in a coordinated way for the decisive experiments that the ITER facility will allow the fusion community to perform and saves a lot of time and resources. Finally, EUROfusion is able to promote fusion within Europe and provide information in a decentralized way to the decision makers and the public at large in a way the ITER Organization never could. In a word, EUROfusion and the ITER Organization have a lot of good reasons to work hand-in-hand. Now DEMO ...   DEMO will be a different machine, demonstrating electricity production and tritium self-sufficiency, with a level of performance expected to go well beyond that of ITER. Our approach to the design of DEMO is based on what I would call a "reasonable extrapolation" of ITER. We know that we will face some serious challenges ... take for instance the blanket modules inside the vacuum vessel. In ITER, they are designed to be "maintained" in case one module fails; in DEMO, due to the neutron fluence, the whole blanket will need to be replaced periodically.   Whereas in ITER replacing the whole blanket (which is not foreseen) would take probably two years, in DEMO we will have to do it without significantly hampering the availability of the machine. This means developing concepts that will allow us to do it in just a few months ...   Do the pre-conceptual studies for DEMO benefit from the experience already acquired in ITER?   One of the lessons learned from ITER is that we should not seek to optimize systems individually but focus intensely on the interactivity between systems. For instance optimizing the coolant is not only a matter related to the optimal operation of the breeding blankets, but one that also impacts the choice of materials, the penetrations through the walls, safety, other systems, plant efficiency, and costs ... to name just a few.   In a few words, what was the outcome of EUROfusion's General Assembly?   We had a very busy agenda this year. First we discussed the future of JET, for which deuterium-tritium experimentation is planned in 2019. In the context of Brexit, this requires an extension of the arrangements for using the facility; at the meeting we made useful steps in that direction. We also made important decisions to upgrade European tokamaks and some other facilities in order to progress a crucial question for fusion—that of the power exhaust, i.e., the control of power by the divertor. In Europe we will be able to explore the broadest set of options in that area, which will provide essential information to operate ITER and prepare DEMO.  

They all gathered—members of the ITER-India team and contractor Larsen & Toubro—to mark a portentous moment: the start of manufacturing on the upper cylinder of the ITER cryostat. In a dedicated workshop at ITER, work is already underway to weld the segments of the cryostat base, which were delivered by the Indian Domestic Agency in late 2015 and early 2016. Just last month, the segments making up the first half (tier 1) of the cryostat lower cylinder were transported to the ITER site. (Manufacturing on the tier-2 segments is underway at Larsen & Toubro's Hazira plant.) Now, work on the third main section has started, with the welding of first upper cylinder T-ribs. The ITER cryostat will be assembled from four large sections—the base (1,250 tonnes), the lower cylinder (375 tonnes), the upper cylinder (430 tonnes), and the top lid (665 tonnes). Just over 28 metres in diameter, the upper cylinder is designed to connect to the top lid of the cryostat on one side, and the lower cylinder on the other. The steel cylinder will be 8.6 metres high when fully assembled, with 50-millimetre-thick walls and 18 rectangular ports. The cylinder is reinforced by toroidal and vertical stiffening ribs on the inner side. The traditional coconut breaking ceremony in March was attended by the head of the Indian Domestic Agency, Shishir Deshpande, and the Vice President of Larsen & Toubro's Process Plant & Nuclear Business Group, Anil Parab. 

Since the signature of a Procurement Arrangement in 2011 with Russia for switching networks, fast discharge units, DC busbars and instrumentation—all key elements of the ITER power supply and superconducting magnetic protection system—specialists from the Efremov Institute in Saint Petersburg have carried out a broad pre-manufacturing campaign including R&D, prototype and testing. In the latest news, type tests have been successfully performed on another batch of equipment prototypes. The power supply equipment procurement package signed by Russia comprises a large variety of electrotechnical components—many of them designed specifically for ITER by the Efremov Institute. The R&D, fabrication and test campaign has been one of the most technically challenging, and expensive, of the 25 systems falling within the scope of Russia's responsibility to ITER.   In late March, specialists from the Efremov Institute completed tests on prototypes of the bypass open switch, the counterpulse circuit for the toroidal field fast discharge unit, and the local control cubicle for the main circuit breaker of the switching network unit prototype.   All of the tests were witnessed by a representative of the ITER Organization, technical responsible officer Francesco Milani. "The results demonstrated the high professionalism in the design and fabrication of one of the most sophisticated power supply systems. The majority of the elements belonging to this Procurement Arrangement are one-of-a-kind components; some of them (the fast discharge units for the toroidal field coils) also classify as PIC (protection-important) components and, as such, they are subject to the regulations imposed by the French Safety Authority. I have to underline that the Russian team is facing this challenge in a very competent way."   The tests, which were completed in 10 days, demonstrated the full compliance of the prototypes with ITER requirements. This opens the way to integration tests with other components, final design reviews and manufacturing readiness reviews. One element of the latest test group—the local control cubicle—is expected for delivery before the end of the year.   Manufacturing is already underway for part of the package (busbars, tested in 2014, and switching network resistors, tested in 2015). Equipment deliveries have been underway since 2015. The delivery of all system components under this Procurement Arrangement must be completed by 2023.

Nine massive steel sectors delivered by the Domestic Agencies of Europe (five sectors) and Korea (four sectors) will be welded together on site during the assembly phase to form the torus-shaped ITER vacuum vessel.  Manufacturing and welding activities are underway now on the many sub-parts that go into the final products—each 600-tonne sector is assembled from four smaller poloidal segments; these segments in turn are created by the welding together of different subassemblies.   In Europe, the first subassembly was achieved for poloidal segment 2 (sector #5) in March.   The photo illustrates how different-sized forgings are machined into complex shapes and then joined together by welding. This sub-assembly, which represents only a fraction of the total sector, weighs more than 6 tonnes and is approximately 2 metres long by 3 metres wide.   In Europe, vacuum vessel manufacturing activities are carried out by the AMW consortium (Ansaldo Nucleare S.p.A, Mangiarotti S.p.A and Walter Tosto S.p.A) and their sub-suppliers. It took 25 metres of welds to finalize the subassembly.   Read the full article on the European Domestic Agency website.

Culham's new tokamak MAST Upgrade is to receive funding to tackle one of the hottest issues in fusion energy research—plasma exhaust. EUROfusion, the European consortium for fusion R&D, has approved the first phase of its contribution to a £21-million program of enhancements to MAST Upgrade, which is only months away from its first operations. Funding for the enhancements, which will be phased from now to 2022, will come jointly from EUROfusion and the UK's Engineering and Physical Sciences Research Council. The controlled exhaust of power and particles from a very hot tokamak fusion plasma, through the divertor area of the machine, is arguably the biggest challenge facing a future fusion power plant. The extreme power loadings (>10 megawatts per square metre—higher than that on a spacecraft re-entering Earth's atmosphere) in a conventional divertor will require regular replacement of reactor components and adversely affect the economics and cost of electricity. It is no surprise, then, that divertor and exhaust physics is a major part of EUROfusion's reactor design work as part of their EU Roadmap to the Realisation of Fusion Energy. See the original article at the Culham Centre for Fusion Energy (CCFE) to find out more about the planned enhancements.