you're currently reading the news digest published from 31 Dec 2018 to 07 Jan 2019



Toroidal field coils | First ITER magnet arrives this year

A major milepost is projected for 2019 as the first of ITER's powerful, high-field magnets is scheduled to arrive from Japan. Let's take a look behind the scenes at the last-stage fabrication activities that are mobilizing the expertise and skill of heavy industry specialists under the responsibility of Japanese QST, the National Institutes for Quantum and Radiological Science and Technology. Eleven years after completing the signatures on documents specifying technical and quality control requirements for the supply of nine toroidal field coils, the Japanese Domestic Agency is overseeing the last, spectacular sequences on its first production unit. The toroidal field coils are the ITER magnets responsible for confining the plasma inside the vacuum vessel using high-performance, internally cooled superconductors called CICC (cable-in-conduit) conductors. Following the completion of the single largest superconductor procurement in industrial history, fabrication of the final coils is proceeding in Japan (9 toroidal field coils plus 10 coil structures to be sent to Europe) and Europe (10 toroidal field coils). Each coil is made up of a superconducting winding pack and surrounding stainless steel coil case. The list of applicable superlatives is long—the toroidal field coils are the largest and most powerful superconductive magnets ever designed, with a stored magnetic energy of 41 GJ and a nominal peak field of 11.8 T. Together they weigh in at over 6,000 tonnes including superstructure, representing 60 percent of the magnetic array on the machine and over one-fourth of the Tokamak's total weight. They require 4.57 km of conductor per coil wound into 134 turns in the central core, or winding pack, of the magnet. And they have required the longest procurement lead-time of any ITER component, with six out of seven ITER Members involved in the production of 500 tonnes of niobium-tin superconducting strand (100,000 km) required for the toroidal field superconducting cables. The first winding pack to come off the assembly line in Japan is currently undergoing final inspection by the industrial consortium of Mitsubishi Heavy Industries/Mitsubishi Electric Corporation. The final sequence of testing involved high voltage tests, helium leak tests, and finally cryogenic tests, during which the winding pack is inserted into a cryostat (see top photo) and cooled to 80 K (-193 ˚ C) to confirm leak tightness. With the successful end of cold testing, the winding pack is now undergoing post-cold-test helium leak tests and high voltage tests and will soon be ready for assembly with its toroidal field coil case. Five other winding packs are in various stages of production. The 200-tonne case assemblies are also in series production. After successful fitting tests early last year, two have been delivered to Europe for insertion activities and a third will arrive this month; another completed production unit will remain at MItsubishi for the assembly of the Japanese coil that is due at ITER in 2019. The fitting tests are the most delicate stage in the coil case manufacturing process, demonstrating that sub-assemblies manufactured and welded at different factory sites can be successfully paired with gap tolerances as strict as 0.25 to 0.75 mm along 15-metre weld grooves. Please see the gallery below for a full update on manufacturing progress.

Coil manufacturing in Europe | Insertion is a success

The first superconducting winding pack made in Europe for ITER's D-shaped toroidal field coils is now ensconced in its 200-tonne protective case. The first-of-a-kind insertion operation was carried out successfully at SIMIC, in northern Italy. On the insertion rig at SIMIC, the 110-tonne winding pack is laid out flat. On either side, the two halves of the steel coil case—the straight inboard segment and the D-shaped outboard segment—have been positioned at the same height. Working within tolerances of 0.2 mm, the insertion tooling slowly brings the "pieces" together and the winding pack disappears inside the heavy steel case. This first successful insertion operation is a prelude to nine others to come, as the European Domestic Agency Fusion for Energy is procuring ten toroidal field coils from winding packs manufactured by the ASG consortium (Europe) and structural cases procured by Japan. SIMIC is the European company that has been selected for final cold testing, insertion and welding activities. Under the contract with SIMIC, winding packs shipped from ASG are cold tested at -193 degrees Celsius (80 K) using a combined cycle of nitrogen and helium. Insertion into the steel structural case comes next, in an operation requiring sophisticated laser dimensional control technology and complex tooling in order to move and fit components weighing hundreds of tonnes with millimetre-level precision. Finally the interior cover plates will be attached and welded in compliance with stringent standards. The thickness of the welds (up to 130 mm) and the fact that welding will have to be carried out from one side only adds to the challenge of this final operation. Welding is expected to take from four to six months, followed by the injection of resin to fill any gaps between the winding pack and the case. Please see the full report on the Fusion for Energy website.

Poloidal field coils | Winding activities end in Russia

Specialists of the Sredne-Nevsky Shipyard and the Efremov Institute in Saint Petersburg have completed the eight double pancake windings required for poloidal field coil #1. After the vacuum pressure impregnation of each double pancake, the team will start assembling the coil. Under the responsibility of the Russian Domestic Agency, the fabrication of poloidal field coil #1 (PF1)—the smallest of ITER's six poloidal field coils—is progressing. Eight double pancakes made from coiled layers of niobium-titanium conductor have come off the fabrication line and six have undergone vacuum pressure impregnation—the phase during which epoxy resin hardens the insulation materials wrapped around each conductor turn and creates a rigid assembly. The impregnated double pancakes will be stacked and joined electrically to form a final nine-metre-in diameter magnet coil weighing close to 300 tonnes. Double pancake winding is a highly precise technical operation that has required the development of advanced technologies and processes. The most important technologies for the fabrication of PF1 were developed at the Efremov Institute (JSC "NIIEFA"), which also designed, manufactured and tested a large part of the equipment. From the signing of the Procurement Arrangement with the ITER Organization in 2011, through the fabrication of poloidal field conductor and the latest milestone—winding completion—development and manufacturing activities have required eight years to date. Coil manufacture is underway at the Sredne-Nevsky Shipyard near Saint Petersburg, where the finalized coil assembly will leave the plant directly atop a barge for the nearby Neva River. (See more on the Shipyard's barge/assembly platform here.) The completed coil is expected early in 2021.

Central solenoid | Module #1 nears completion

US ITER and contractor General Atomics recently achieved a major milestone in the fabrication of the ITER central solenoid, completing vacuum pressure impregnation (VPI) on the first production module. The VPI process is the penultimate step of fabrication that turns almost 6 km of carefully wound superconducting conductor into a structurally strong, electrically insulated electromagnet. 'Completion of VPI is a critical step in the process and the team worked diligently and with great care to insure its success,' said John Smith, project manager for General Atomics. 'The first production unit now looks like a central solenoid module, and it won't be too much longer before it is complete and begins to function as one.' The central solenoid, often called the 'heart of ITER,' is essential for operation, serving to initiate plasma and generate the necessary current for plasma heating and sustainment. Six modules will be stacked to form the 1,000-tonne central solenoid, which will be the largest pulsed superconducting magnet in the world when it is complete. General Atomics is under contract to US ITER to fabricate the six modules plus one spare. During vacuum pressure impregnation, the team evacuates a rigid mold encasing the coil and injects a three-part epoxy mixture to impregnate the insulation materials wrapped around each conductor turn, plus the ground insulation around the module itself. The epoxy provides both electrical insulation and structural support to the module. In a final fabrication step, piping is added and the assembly undergoes final testing. Fabrication of the modules began in 2016 at the General Atomics Magnet Technologies Center in Poway, California. The manufacturing process takes approximately 22-24 months per module plus an additional 5-6 months of testing. Five modules are currently in various stages of production. General Atomics has been a pioneer in fusion research and development for over 50 years and is also home to the DIII-D National Fusion Facility, funded by the Department of Energy through the Office of Fusion Energy Sciences.

On site | Strategic and symbolic buildings change hands

Constructing and delivering the installation's buildings to the ITER Organization is a major part of Europe's contribution to the ITER Project. On Friday 21 December 2018, the last working day of the year, an important milestone was passed as a large area on the north of the platform was handed over to the ITER Organization by the European Domestic Agency Fusion for Energy. 'There is something highly symbolic in the nature of the buildings we are receiving today,' said ITER Director-General Bernard Bigot in his address. 'They all belong to the installation's heat rejection system and they are what makes ITER unique among fusion machines — a tokamak that will produce considerable amounts of energy for a significant duration and overpass the breakeven of input/output ratio.' Designing and fabricating the high-performance system that will evacuate the heat generated by the ITER plasmas was part of India's contributions to ITER; building the concrete basins and infrastructure was the work of Europe, and installing the equipment will be the responsibility of the ITER Organization. For Director-General Bigot, this realization was "yet another clear demonstration of the One Team spirit and ITER values among all the stakeholders.'


ITER Business Forum: register now

Registration is open now for the 2019 edition of the ITER Business Forum (IBF/2019) to be held in Antibes, France from 26 to 28 March. At IBF/2019, representatives of the ITER Organization, the Domestic Agencies, and main suppliers will be making presentations on industrial involvement in the project, procurement opportunities, and main future calls for tender. In specific thematic sessions, registered delegates will have the opportunity to meet potential partners or subcontractors at the French, European or international level. A 1-1 meeting schedule tool is also available on line for all registered companies. To find out more about the conference, to register to participate, or to reserve a stand, please see the IBF/2019 website.

Is fusion's future on the Moon?

Like mountaineers at the foot of Mount Everest, spacefaring nations have aimed for the Moon 'because it's there.' Now, close to 60 years after the first object from Earth landed (or more accurately 'crashed') on the surface of our satellite and half a century after Apollo 11 gently deposited two men on the Sea of Tranquility, there are very concrete incentives to 21st century lunar exploration. And one of these incentives has to do with the future of fusion. Research today is essentially focused on the fusion of hydrogen isotopes deuterium and tritium, which is the 'easiest' to achieve with our present technological capabilities. However, other energy-producing combinations of light nuclei are theoretically possible, a few of which involve the helium isotope 3 (3He). Fusing 3He with itself or with deuterium offers the immense advantage of not producing neutrons and hence avoids activating materials in the fusion chamber. Carried by solar wind, 3He is prevented from reaching the surface of our planet because of the magnetic field that protects it. On the Moon however, where the magnetic field is considerably weaker, large quantities of 3He have accumulated close to the surface. For many years, some scientists, politicians, and private companies (and even a former Apollo astronaut) have made the argument for 'mining the Moon' for 3He. Other scientists argue that mining the Moon for 3He is pure ... moonshine. Despite the controversy, 3He recently made headlines in relation with the recent landing of the Chinese rover Chang'e 4 on the dark side of the Moon. Professor Ouyang Ziyuan, the Chief Scientist of the Chinese Lunar Exploration Program, was widely quoted saying that a long-term industrial program to mine the Moon for 3He was economically justified. 'The moon is 'so rich' in helium 3,' he said, 'that it could solve humanity's energy demand for around 10,000 years at least.' Photo: The Chang'e 4 module landed on the dark side of the Moon on 3 January 2019.


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