ITER is being designed so that it could be built on the territory of any of the Parties, with options which provide the capability for conducting experiments from remote centres throughout the participating countries.

The site should cover a total available surface area of about 40 hectares with another 30 hectares available temporarily nearby for use during the construction period. Other key site requirements for ITER include thermal cooling capacity on average of 450 MW and electrical power supply of up to 120 MW steady-state.

The arrangement of the ITER buildings (for a generic site) is shown below (animated views are also available). The tokamak building is located centrally, with electrical, cooling, personnel, and waste entering or leaving from separate quadrants. This avoids crossing of services, thereby simplifying system interfaces and minimising connection distances. To the maximum extent possible, the design is made so as not to preclude future additions in system capacity.

ITER buildings house, support, protect, control access to, provide suitable environmental conditions for, and provide services to the components, systems, and operations which are located within them. The ITER buildings have been optimised to provide the lowest cost design solution which adequately meets the mission requirements and the appropriate standards for the public and workers, as well as investment protection. There are two main classes:

• radiologically controlled buildings - tokamak building, tritium building, hot cell building, low-level radwaste building, and personnel access control building;
• conventional buildings.

The tokamak building in particular is important for its contribution to plant safety, as it provides:

• a biological shield of borated concrete to avoid activation of components and to allow personnel access not long after the plasma is shut down;
• a second confinement (even containment) barrier around the neutral beam and cooling system vaults, and a third barrier against leakage of tritium;
• segregated zones around the tokamak held under differential pressure by the air conditioning system to ensure that any accidental spread of contamination is from regions of low to already higher contamination;
• appropriate shielding to allow transport of activated in-vessel components from the tokamak to the hot cell.

The tokamak and tritium building structure is made very robust by locating them on the same stiff concrete slab ("basemat") designed to resist seismic conditions. Should a seismically active site be chosen, accelerations can be kept below allowable limits by use of conventional seismic isolators.

Among the conventional buildings, the cryoplant buildings have a dual purpose, whereby they are used for PF coil fabrication early in construction, and change to their operational use later in construction. For this reason their construction is planned as early as possible, with completion planned well before the tokamak building.

Further information on all aspects of the ITER buildings can be found in the Technical Basis.