ITER Newsline / 21 April 2017


 
A note to our readers: Newsline will not be published until Monday 4 September.
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 FEATURED

A wide angle on progress

Whether captured from the top of a crane or from a drone hovering at an altitude of a few dozen metres, the ITER site isalways spectacular. After almost seven years of construction most of the elements of theITER scientific installation are visible,albeit in various stages of completion. Progress has been strong in the centre of the Tokamak Complex, where the bioshield now rises two storeys above the level of the platform and has become one of the most noticeable features of the worksite from overhead. Construction progress is also evidentin the zonesreserved forthe ITER cryoplant and thecooling towers/basins. Othermilestoneshave been achieved that aren't sovisible from the sky, however. On 30 March, one of the four transformers for steady-state electrical network was briefly connected to the French grid—opening the way for full switchyard "energization'in the coming months. And that's not all: inside the Poloidal Field Coils Winding Facility teams areabout to start on thefirst production winding for poloidal field coil #5; in the Radio Frequency Building 80 percent of the steel structure of has been installed and the intermediate floor slabs realized; and in themagnet power conversion area the first 'top beam' was installed on columnslast week. But better see it with your own eyes in the photo gallery below ...

Inside the arena

A visit to the deep "well" where the ITER Tokamak assembly will begin next year begins with a journey underground ... through a maze of giant pillars, omnipresent scaffolding and spiral staircases. This is a place where one can get easily lost. Access, safeguarded pathways, and metal staircases move as work progresses and once-familiar itineraries often turn into dead ends. But there's a reward to this erring. Having found (and climbed) the proper staircase, the view opens at last to what we have come to see: a concrete arena, bristling with steel rebar. Thescene that sets the stagefor one of the most awesome experiments in human history. Soon, though, the view will change. The installation of a temporary steel cap—whose purpose is to protect teams below while allowing work to continue on thebioshield, above—willhide the lowest level of the Tokamak Pit from our view.

10,000 tonnes of magnets to cool

In ITER, huge volumesof liquid helium will be circulated throughout a complex, five-kilometre network of pipes, pumps and valves to keep the 10,000-tonne magnet system at superconducting temperature. Helium will also be required to provide cooling power to the thermal shields—which reduce the large temperature gradient between the superconducting magnets and the Tokamak environment—and the cryopumps, which use extreme cold to achieve high vacuum in the plasma chamber. As a consequence, the ITER cryoplantwill be the largestin the world. Nearly 25 tonnes of liquid helium at minus 269 °C will circulate in the ITER installation during operation. Helium however is not the only ultra-cold fluid that the cryoplant will produce. Liquid nitrogen, at a temperature of minus 196 °C, will be used as a 'pre-cooler' in the liquid helium plants. Nitrogen, which accounts for approximately 78 percent of the air we breathe, will be extracted directly from the atmosphere in an on-site gaseous nitrogen generator with a production capacity of 50 tonnes per day, and then processed in two large liquid nitrogen plants. The complexity of the cooling processes, along with the flux rate required for the cooling of magnets, cryopumps and thermal shield, has dictated the size and design of the cryoplant. Construction is underway now on the buildings and technical areas of the cryoplant. The images below show recentprogress on site. Access for the first installation activities is expected in June.

Heaviest convoy yet

The triple convoy that reached ITER on Thursday 13 April wasthe heaviest ever organized since the beginning of "highly exceptional" deliveries in January 2015. Two 278-tonne electrical transformers and one 150-tonne helium tank were delivered in a three-trailer convoy that travelled at night. The two mammoth transformers are part of a set of three destinedfor ITER's pulsed power electrical network, responsible fordelivering DC current for plasma operations (power injection into the magnets, plasma heating ...). One of the transformers was delivered last June and has been installed in its permanent position on the platform;transformer "bays" have been createdto receive the two others. The helium tank is part ofEurope's contribution to the ITER cryoplant. Thetank will be installedvertically in the exterior storage area of thecryoplant zone, along with five other similar containers (see a schematic of the area here). The six-tank set, each holding 400 cubic metres of gas, will act as a buffer to keep the gas/liquid balance in the cryogenic system, and store the helium inventory when the Tokamak is in shutdown or in case of a magnet quench.

 IMAGES

United colours of ITER

The seven flags of the ITER Members—and one for the ITER Organization—fly proudly over the construction site in Saint Paul-lez-Durance, France.

 IN THE MEDIA

Fusion Now, NRFI

"국가대표라는 자부심으로 일한다" - ITER 섹터부조립장비 제작 맡은 태경중공업

Gov.UK

£21 million investment for MAST tokamak upgrade

DagensHäringsliv.se

ITER:s "tokamakarena" tar form



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