Subscribe options

Select your newsletters:


Please enter your email address:

@

News & Media

Latest ITER Newsline

  • Heating | A pinch of moondust in the ITER plasma

    One day in the distant future, fusion plants might be fuelled by helium 3—an isotope that is extremely scarce on Earth but reputed to be abundant on the Moon. B [...]

    Read more

  • Delivery | 2,000 km through canals, locks and tunnels

    When the thruway is closed, one takes the back roads. And when it's low-water season on the Rhine-Rhône canal, a barge leaving Switzerland for the Mediterranean [...]

    Read more

  • Monaco Fellows | A hand in shaping ITER

    For the sixth time, ITER is welcoming a group of five young researchers as part of the Monaco-ITER postdoctoral fellowship scheme. Working alongside experienced [...]

    Read more

  • On site | Drone survey on a perfect day

    There are days in winter when the skies over Provence are perfectly transparent. Snowy peaks 200 kilometres away appear close enough to be touched and farms, co [...]

    Read more

  • AAAS conference | ITER on the world science stage

    With more than 120,000 members globally, the American Association for the Advancement of Science (AAAS) is billed as the world's largest scientific society. The [...]

    Read more

Of Interest

See archived entries

Radial walls

Thickest rebar and most intricate geometry

The combined mass of the ITER Tokamak and its enveloping cryostat is equivalent to that of three Eiffel Towers. But not only is it heavy (23,000 tonnes) ... it is also "alive." In the course of operation the machine will jump and bounce (slightly), wobble, shrink, and expand—all the while transferring considerable force to the Tokamak Building basemat and bioshield wall.

In the cavernous space of the lower Pit, workers are implementing processes and methods that have been validated on the real-size mockup. The grey structures with orange and yellow marking are temporary supports for the massive steel transition pieces. (Click to view larger version...)
In the cavernous space of the lower Pit, workers are implementing processes and methods that have been validated on the real-size mockup. The grey structures with orange and yellow marking are temporary supports for the massive steel transition pieces.
In order to allow for the smooth transfer of these forces, the Tokamak support system will need to be extremely robust, with a strong connection to the building's structure, and yet also allow for a certain freedom of translation and rotation for the cryostat.

Connection and stability will be achieved by way of a massive pedestal—a concrete "crown" connected to walls that are radially anchored in the bioshield. Eighteen radial walls will act as the flying buttresses of a gothic cathedral, evenly distributing loads and effort.

Movement will be permitted thanks to a circular arrangement of 18 spherical bearings, acting like ball-and-socket joints that will transfer the horizontal and rotational forces generated by the tokamak.

The densest, thickest and most intricate rebar arrangements of the entire installation will be required for the crown and radial walls—to the point that it was necessary to build a full-size mockup, reproducing a 20-degree section of the structure, in order to demonstrate its full constructability.

One of the most strategic parts of ITER construction, the crown and radial walls necessitate the densest, thickest and most intricate rebar arrangements of the entire installation. The structure should be finalized by the end of the summer. (Click to view larger version...)
One of the most strategic parts of ITER construction, the crown and radial walls necessitate the densest, thickest and most intricate rebar arrangements of the entire installation. The structure should be finalized by the end of the summer.
As procedures are successively validated on the mockup, they are implemented on the actual construction underway on the floor of the Tokamak Pit.

Since the temporary "lid" split the Pit in two in August, the area has been transformed from an open arena to a cavernous place, resounding with the clanging of metal and the warning signals of the circular crane and aerial work platforms.

Workers are busy installing the steel reinforcement for each radial wall: thick rebar (up to 50 millimetres in diameter) arranged in a complex geometry, and massive steel transition pieces (three tonnes each) that will transfer and distribute the loads to the concrete civil work.

From both a structural and safety perspective, the crown and its radial walls are one of the most strategic parts of the ITER installation. They should be finalized by the end of the summer.

There is one 3-tonne steel transition piece per radial wall. Their function is to transfer and distribute the loads to the building structure. (Click to view larger version...)
There is one 3-tonne steel transition piece per radial wall. Their function is to transfer and distribute the loads to the building structure.


 


return to the latest published articles