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  • FEC2020 | Seeking sponsors for 28th IAEA Fusion Energy Conference

    For only the third time since 1961, the International Atomic Energy Agency's Fusion Energy Conference will be taking place in France—hosted jointly by the Frenc [...]

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  • Nuclear safety | Under constant scrutiny

    Because one of the elements involved in the fusion reaction is the radioactive isotope tritium, and because the hydrogen fusion reaction itself generates a high [...]

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  • Power conversion | Alien structures and strange contraptions

    There are places in ITER that seem to belong to another world, places full of alien structures and strange contraptions. The feeling—a mixture of awe and puzzle [...]

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  • Tokamak Complex | A changing landscape

    For the past three years, the view from the top of the highest worksite crane has not changed much. Inside of the Tokamak Complex, 80 metres below, concrete gal [...]

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  • Ion cyclotron heating | How to pump 20 MW of power into 1 gram of plasma

    To power the ion cyclotron system, the ITER Organization and its partners are designing not only new antennas, which will be housed in the tokamak vessel, but a [...]

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Of Interest

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The Seismic Pit basemat is now complete

An important milestone in the project's schedule: the pouring, on 22 December, of the twenty-first and last concrete slab of the Seismic Pit Basemat. (Click to view larger version...)
An important milestone in the project's schedule: the pouring, on 22 December, of the twenty-first and last concrete slab of the Seismic Pit Basemat.
There is no traditional ceremony attached to the completion of the foundations for a future home as there is one, called a Topping Out, to celebrate the laying of a roof.

Had there been one, ITER, F4E and their contractor GTM could have raised a glass to an important milestone in the project's schedule: the pouring, on 22 December, of the twenty-first and last concrete slab of the Seismic Pit basemat.

Work on this 1.5-metre-thick structure began before dawn on a warm August day six months ago. Since then, some 18,000 m³ of concrete have been poured over a dense array of steel rebar and stirrups—some 3,400 tonnes of metal in all.

In order to insure close-to-perfect homogeneity of the basemat, each slab had to be poured in one continuous operation lasting no more than an extended workday. Considering that the pumps could deliver an average of 100 m³ of concrete per hour, the 11,500 m² surface of basemat was broken down into 21 sections, each to be filled successively with 800 m³ of concrete.

In order to ensure ''close to perfect'' homogeneity, each slab had to be poured in one continuous operation lasting no more than an extended workday. (Click to view larger version...)
In order to ensure ''close to perfect'' homogeneity, each slab had to be poured in one continuous operation lasting no more than an extended workday.
This slab-by-slab technique also reduced the forces exerted by concrete "shrinkage" on the steel rebar.

The Seismic Pit basemat was designed to be extremely strong. It supports the anti-seismic pillars and bearings upon which the Tokamak Complex basemat will rest, and will ultimately bear the 360,000 tonnes of the Tokamak Complex.

A central area of the basemat—approximately 80 m²—was reinforced to bear the weight of the mammoth central column assembly tool that will operate during the machine assembly phase on the Tokamak Complex basemat. This extra strength was achieved through an increased density of stirrups.

Upon the now-finalized basemat, 159 seismic bearings (out of a total of 493) remain to be installed over the next two months. Twenty percent of the retaining walls have been completed and two parallel operations will commence this spring: a much smaller (5,500 m²) and relatively shallow excavation for the Assembly Building basemat and, prior to rebar reinforcement, horizontal wooden formwork and scaffolding for the next basemat that will be poured: the Tokamak Complex basemat.


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