Work began in August 2011 on the ground support structure of the Tokamak Complex, the 360,000-ton edifice that comprises the Tokamak, Diagnostic and Tritium buildings.

The Seismic Isolation Pit is now done: seventeen metres below the surface of the platform, the concrete basemat, retaining walls, and seismic pads of the Seismic Isolation Pit are in place to protect the buildings and the equipment from ground motion in the case of a earthquake.

The ground support structure comprises a 1.5-metre-thick basemat and retaining walls that maintain and stabilize the surrounding rock, as well as waterproof the Seismic Pit. On the level surface of the basemat, 493 columns, or plinths, have been cast, each one topped with an anti-seismic bearing made of alternate layers of metal and rubber. With a capacity for lateral movement of 10 cm, the bearings are capable of filtering and absorbing the accelerations linked to ground motion.

The floor of the Tokamak Complex will rest on top of these seismic bearings, each plinth bearing an equal amount of load. The three buildings of the Tokamak Complex will share a single foundation: as a single, monolithic structure, the relative displacement of process pipes between buildings is avoided.

The civil works of the Tokamak Complex will be launched late 2013. Before that, the basemat for the Complex, the B2 basemat, will be created in three stages: propping and formwork (ending July 2013), reinforcement (ending September 2013) and concrete pouring (August to December 2013).

In total, the Seismic Pit basemat, the reinforced concrete walls, the 493 plinths, and the Tokamak Complex basemat will require the casting of approximately 100,000 tons of concrete. A dedicated batching plant on site, with two mixing machines and eight holding tanks, limits transportation in the area of the ITER construction site and secures supply.

To one side of the Seismic Pit, work began in May 2012 to excavate the Assembly Building. In this vast antechamber to the Tokamak Building, specialized assembly tools will be installed to carry out pre-assembly activities prior to the integration of components into the machine.

Click here to view recent videos of construction progress.