Subscribe options

Select your newsletters:


Please enter your email address:

@

News & Media

Latest ITER Newsline

  • Making remote handling less remote

    Over a wet and windy three-day period on the ITER site in November, around 90 representatives of the ITER Organization, the Domestic Agencies of Europe and Japa [...]

    Read more

  • The framework for sharing ITER intellectual property

    In signing the ITER Agreement in 2006, the seven ITER Members were agreeing not only to share in the costs of constructing and operating the ITER facility, but [...]

    Read more

  • Wendelstein achieves ultra-precise magnetic topology

    A recent article in the online journal Nature Communications confirms that the complex topology of the magnetic field of Wendelstein 7-X—the world's largest ste [...]

    Read more

  • The Matrix, rigid and fluid

    A fast-growing array of structures and buildings has been emerging across the ITER worksite platform under the control and supervision of the European Domestic [...]

    Read more

  • By road, river and sea

    They travelled by road from the Air Liquide factory near Grenoble, sailed down the Rhône River from Lyon and entered the Mediterranean to the east of Fos-sur-Me [...]

    Read more

Of Interest

See archived articles

Trying on the Tokamak crown

-R.A.

On the very place where the ''B2 slab'' mockup was standing just a few months ago, a new Tokamak support system (''crown'') mockup has been under construction since the end of 2014. (Click to view larger version...)
On the very place where the ''B2 slab'' mockup was standing just a few months ago, a new Tokamak support system (''crown'') mockup has been under construction since the end of 2014.
A crown usually sits on a king's head, or on the top of prestigious buildings such as cathedrals or skyscrapers.

In ITER, the "crown" sits under the machine: it is the structural element that supports the combined mass of the cryostat, vacuum vessel, magnet system and thermal shield—in short, the support system for the 23,000-ton machine. From both a structural and safety perspective, it is one of the most strategic parts of the installation.

Designing the ITER crown has proved an utterly complex and challenging task, involving several ITER departments as well as experts from the ITER European agency and its architect-engineer Engage.

The crown's complexity stems from the fact that the huge mass that it will support will not be an idle one. In the course of operation, the ITER Tokamak might slightly "up-lift", wobble, or shrink...causing considerable load transfers from the machine to the Tokamak Building basemat.

In late 2012, following some ten months of collaborative effort, the crown design was finalized: it will consist of a thick, circular concrete structure connected to the three-metre-thick bioshield by radial concrete walls. 

The mockup will consist in a 20° segment of the Tokamak crown, complete with a one-metre-thick radial wall and a three-metre-thick section of the bioshield. (Click to view larger version...)
The mockup will consist in a 20° segment of the Tokamak crown, complete with a one-metre-thick radial wall and a three-metre-thick section of the bioshield.
In order to allow for the smooth transfer of horizontal and rotational forces generated by the movement of the Tokamak, 18 spherical bearings acting like ball-and-socket joints will be installed between the concrete crown and the steel ring that acts as the interface with the cryostat.

Actual construction, however, is a long way from 3D design documents. When a structural element is as complex and as strategic as the ITER crown, an intermediate step is necessary to demonstrate constructability.

"Just like for the Tokamak Complex basemat slab, we need to be certain that the rebar principles we have opted for are constructible, and we need to qualify the bespoke concrete formula," explains ITER's Nuclear Buildings Section leader Laurent Patisson. "And there's only one way to do this: by trying it first on a real-size mockup."

On the very place where the "B2 slab" mockup was standing just a few months ago, a new mockup has been under construction since the end of 2014. When completed, the large structure will reproduce a 20° segment of the Tokamak crown, complete with a one-metre-thick radial wall and a three-metre-thick section of the bioshield.



return to the latest published articles