The first floor of the Tokamak Complex, known as the basemat, has been completed. This is an important achievement for F4E as it marks the end of a major civil works contract and the beginning of the construction phase.
The Tokamak slab marks the conclusion of the preparatory phase of the construction site which started in August 2010 and represents an investment of around 100 million EUR for F4E. It comes as an addition to the completion of the galleries around the Tokamak pit, the temporary road network, the Contractors Area and the underground networks.
Those four years of hard work have been challenging for all parties involved in the ITER project: ITER International Organization, F4E , the companies collaborating under the Architect Engineer contract and all F4E contractors involved in this domain.
“The design and validation process were extremely challenging because of the difficulty to combine all requirements in a sound and practical way” explains Miguel Curtido,F4E's Technical Project Officer. The B2 slab is part of the shielding and confinement barrier of the future Tokamak, and as such it is considered a “Protection Important Component” (PIC), subjected to heavy scrutiny from both ITER Organization and the French Nuclear Regulator. It is the first concrete which had to comply with the full set of nuclear safety requirements. It is worth remembering that ITER will be the biggest nuclear facility in France and the first ever nuclear fusion facility.
The combination of high density reinforcement in the central area (around 350kg/m3), with interfaces of orthogonal and radial layouts, combined with a largereinforcement diameter(40mm) and extremely tight tolerances for the placement of the embedded plates (up to 3 mm in some cases), made the execution very challenging.
“The main priority for all teams was to ensure maximum safety and quality levels given the complex construction and the tight schedule”, adds Miguel Curtido.
The concrete pouring of this huge slab, covering an area of 9600m2, started in December 2013. The hold point was released by the French Nuclear Authority on July 10, and the central 9 sections of the slab were poured within 7 weeks. This was made possible thanks to the personal commitment of all the people involved, working during the holiday period, night shifts and weekends when necessary.
150 workers have used 14000m3 of concrete, 3,600 tonnes of steel and 2,500 embedded plates in total. Ben Slee, F4E Technical Officer responsible for the building construction explains: “It is not only those working on the construction site but also hundreds of others in the areas of design, procurement, scheduling, quality assurance and finance that have been involved since the preparation and signature of the contract”.