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Latest ITER Newsline

  • Cryostat thermal shield | A "strong back" for a fragile component

    The lower cylinder thermal shield is a large silver-plated component, circular in shape and five metres tall, which fits inside the depression in the cryostat b [...]

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  • Diagnostic shielding | B4C ceramic bricks prove their worth

    A number of materials can effectively shield diagnostic equipment from the neutron flux coming from the plasma. To find the best one, the diagnostics team at IT [...]

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  • Image of the week | The cryostat top lid, batch after batch

    Batch after batch, the elements for the top lid of the ITER cryostat keep arriving from India. As of today, 7 out of the 12 required segments have been delivere [...]

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  • Cooling water system | The tanks within a tank

    Deep inside the bowels of the Tokamak Building, the entrance to one of most spectacular rooms of the whole installation resembles that of a broom cupboard. [...]

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  • ITER assembly | Last major assembly contract signed

    One year after finalizing two major machine assembly contracts, the ITER Organization has chosen the contractors who will carry out assembly and installation ac [...]

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Of Interest

See archived entries

Pouring the protective circle

Since construction of the ground support structure for the Tokamak Complex began in 2010, huge volumes of concrete have been poured to form the edifice's seismic foundations, retaining walls, and basemat. Since November 2014 work has been underway on the Complex's basement-level walls and pillars.

In the early hours of Wednesday, 21 October, workers poured the first 200° segment of the bioshield, in an all-day operation that took some 15 hours to complete. (Click to view larger version...)
In the early hours of Wednesday, 21 October, workers poured the first 200° segment of the bioshield, in an all-day operation that took some 15 hours to complete.
But concrete pouring in a nuclear building is never routine, with each pour day marking the end of months of calculations, modellization and painstaking preparation.

For the ITER bioshield—the 3.2-metre-thick "ring fortress" surrounding the machine, whose role is to protect workers and the environment from the radiation generated by the fusion reaction—preparations have been particularly complex. Realizing a "perfect pour" for such a massive and strategic structure is so important that it was practised in a specially constructed full-scale mockup on the platform.

The density of the lattice of steel reinforcement makes the use of traditional concrete vibrators—used to encourage the concrete to reach every recess—impractical. As a consequence, an extra-fluid, self-compacting concrete was selected by the contractors and trialled in the on-site mockup.

At the end of the day 600 m³ of concrete were in place (centre circle), filling over half of the bioshield's circumference. (Click to view larger version...)
At the end of the day 600 m³ of concrete were in place (centre circle), filling over half of the bioshield's circumference.
The conclusive results allowed pouring operations to begin. In the early hours of Wednesday, 21 October, workers poured the first 200° segment of the bioshield, in an all-day operation that took some 15 hours to complete.

As dusk settled on the ITER site 600 m³ of concrete were in place, filling over half of the bioshield's circumference. The pouring of the remaining 160° segment is scheduled in January 2016.


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