ITER Newsline / 14 September 2017

A note to our readers: Newsline will not be published again until Monday 19 March.

ITER platform
From every angle

The ITER platform is changing fast: buildings that were just steel and concrete skeletons a few weeks ago now have roofs; ongoing cladding operations herald the architectural harmony that will be the rule for all structures (with the exception of the poloidal field coil winding facility and the Cryostat Workshop, which are not covered in mirror-like stainless steel and grey-lacquered metal); and at the heart of the installation, the bioshield seems never to stop rising ... This latest series of aerial photographs also reveals the growing density of construction projects and, when inspected closely, the intensity of traffic — vehicles of all kinds on the move to deliver material and equipment to the different zones and the multiple projects at various stages of completion. The ITER site is now home to 2,000 workers; bringing the total of people on site to more than 3,500 if one includes the scientific, technical and administrative personnel inside the ITER Headquarters and temporary office structures. That is more than four times the population of the village that hosts it.

The lid is on

At any given level of the Tokamak bioshield, different companies are involved with construction tasks; this is called 'co-activity' and it requires careful coordination. In some cases co-activity also calls for the installation of special structures to provide the required safety for all workers involved. As work progresses on the upper levels of the massive circular bioshield, construction of the Tokamak support structure (the 'crown') will soon begin on the ground floor ("B2 slab") of the Tokamak Building directly below. In order to protect workers on the the lower-level, a circular platform (the 'lid') was installed in August, supported by massive steel structures. The lid has three openings—one for the vertical support structure of the central tower crane, and two for allowing the hook to pass with material and equipment for construction projects on the the ground floor. Once delivered through the lid's opening, material and equipment will be handled by a circular gantry crane, running 360 degrees on the lowest level of the bioshield 'well.' The lid will also be used as a storage platform for materials needed by the VFR consortium for works on the upper levels of the bioshield.

Electrical power
A cascade of transformations

Before it reaches the Tokamak's superconducting magnets, the electrical power from the 400 kV switchyard undergoes a cascade of transformations. First, three very large pulsed power electrical network transformers—situated adjacent to the switchyard—bring the voltage down from 400 kV to 66 kV and 22 kV. This reduced voltage is then fed to the converter transformers inside of the twin Magnet Power Conversion buildings. The converter transformers are each dedicated to a specific magnet system (central solenoid, toroidal field coils, poloidal field coils, correction coils). Their role is to bring down the voltage further—to approximately 1 kV. (The precise voltage is determined by the individual magnet system.) All 44 converter transformers are paired with large 'rectifiers' whose function is to convert the 1 kV AC current into direct current (DC), just like an 'adapter' for laptops or cell phones transforms the 110 or 220 volts from the AC current into 9, 12, or 24 volts of DC current. China is responsible for procuring the converter transformers and rectifiers for the poloidal field coils; Korea for all the other superconducting magnets; and Russia for the 25 km of busbars that connect the different components inside the Power Conversion Buildings. (Aluminium busbars in ITER can carry up to 7,000 times more current than a washing machine power cable.) In July, the first of twelve transformers required for the central solenoid magnet system was successfully tested at the Hyosung Factory in Changwon, Korea, along with the set of high AC current busbars to connect it to the corresponding rectifier. Delivery to ITER can now be anticipated early next year. Six of the central solenoid transformers will need to be in place by First Plasma, while six others will be installed at a later phase.

Fusion world
Wendelstein 7-X resumes operation

The Wendelstein 7-X stellarator is up and running again, following a shutdown phase dedicated to equipping the machine for longer discharges and higher heating power. The world's largest fusion device of the stellarator type is back in action. Plasma experiments have resumed after a 15-month shutdown phase, during which over 8,000 graphite wall tiles and ten divertor modules were installed in the plasma vessel. This high-tech cladding that will protect the vessel walls and allow higher temperatures and plasma discharges lasting 10 seconds. The geometry of the new divertor, with plasma-facing tiles that conform exactly to the twisting contour of the plasma edge, is considered power plant relevant for the first time—particularly in the ratio of the divertor area to the plasma volume. 'We are therefore very excited that we are now able to investigate whether the divertor concept of an optimized stellarator can really work properly,' says Project Head Professor Thomas Klinger. All ten microwave transmitters of the microwave heating system have been brought on line, which will permit higher density and higher temperature plasmas and lead possibly to the enhanced thermal insulation of the plasma in the optimized device. New diagnostic instruments will also allow the observation of plasma turbulence for the first time. The goal of the Wendelstein 7-X project is to investigate the suitability of the stellarator type of fusion device for a continuous-operation fusion power plant. Following the conclusion of main assembly in 2014 at the Max Planck Institute for Plasma Physics (IPP) in Greifswald, Germany, the machine achieved its first helium plasma in December 2015 and its first hydrogen plasma in February 2016. Read the full press release on the IPP website.

Assembly Hall
Anchoring a giant tool

The first assembly activities have been carried out for the largest tool in the ITER arsenal—the giant sector sub-assembly tool (SSAT) that will be strong enough (and tall enough) to suspend a 440-tonne vacuum vessel sector during pre-assembly activities. The ground-level elements of the tool are now in place. In the first in-situ assembly operations, the rail base plates of the SSAT tool were mechanically installed onto waiting fixtures. In the next few days, these plates will be grouted onto the reinforced floor slab and the first rail components installed. The plates provide the fundamental supporting structure for the rails and the moving platform of the tool's lateral wings. Driven by precision hydraulics, the wings will rotate to deliver a D-shaped toroidal field coil and vacuum vessel thermal shield segments for installation on either side of the vacuum vessel sector. Jens Reich heads the Tokamak Assembly Section/Division that drafted the design of the plates and issued the drawings for manufacturing. His group will also control alignment throughout the installation process. 'This successful first operation of SSAT assembly is exciting for my whole team. We have been planning for the ITER installation and assembly phase for years, and now we have realized the first tangible activity.' In the Assembly Hall, two of these giant tools will be in action to equip the nine vacuum vessel sectors, one by one, before the completed sub-assemblies are transferred to the Tokamak area for installation. The rail base plates were manufactured by CNIM in Toulon, France—the company selected as the subcontractor to tool manufacturer Taekyung Heavy Industries (Korea) for onsite assembly activities. Throughout the installation and alignment of tool components ahead, the rail base plates will serve as the "zero level" reference point.

ITER Games
A sense of belonging

Like the Olympics, the ITER Games are not about winning—although there is excitement when one does! They are about participating together, meeting new people, and having fun. Seven years ago, the idea behind the Games was to create a popular event that would facilitate the integration of the ITER personnel into their new environment. This has been largely accomplished: whether they work directly for the ITER Organization, the European agency for ITER (Fusion for Energy) or for subcontracting companies, the thousand and more 'ITER families' have now acclimated into the local communities. This sense of belonging was obvious as the 7th edition of the ITER Games unfolded on Saturday in Vinon-sur-Verdon, the village nearest to the ITER site. Some 350 participants—a mix of 'ITER people' and of residents from local communities—teamed up with colleagues or with friends to compete in a number of friendly matches. The rain had been threatening since early morning. It began to pour as the participants were gathering to receive their trophies and rewards, causing everyone to move from the large plazza at the heart of the village to the nearby community centre. Sports games are like weddings: the rainier they are, the happier. More photos are available on the Agence Iter France website.

A note to our readers: not all the press clippings that appeared in the media on ITER in the last seven days can be listed here. Please see this page for a more exhaustive list.


AV ČR: Mezinárodní letní škola fyziky plazmatu


Physicists propose new way to stabilize next-generation fusion plasmas

땅 위의 '인공태양' 난제 해결

World Nuclear News

Rosatom head visits Iter, latest equipment batch sent

Казахстанский токамак готовят к запуску. Фоторепортаж

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