The ITER bridge cranes can work together to lift loads of up to 1,500 tons, or operate separately. Image credit: ITER Organization

In order to successfully manoeuver hundreds of very large Tokamak components into position, a very precise, made-to-order set of tools is currently under construction.

The lifting system will be comprised of a pair of independent bridge cranes mounted on rails that run the entire length of the Tokamak and Assembly buildings to form a continuous, 175 metre-long crane bay. Working together, the four 375 ton main hoists will handle loads of up to 1,500 tons. The central solenoid—the magnet in the centre of the machine—will be the tallest lift of assembly operations (18.2 metres). The heaviest single load will be the base section of the cryostat, which weighs in at 1,200 tons. In some cases, components standing 20 metres high and weighing hundreds of tons will have to be manoeuvered into position within tolerances of 2-3 millimetres.

A special "sub-assembly" tool will suspend each of the nine sectors of the vacuum vessel from its top, install associated thermal shielding, and rotate two toroidal field coils into position. Standing 22 metres tall, the "sub-assembly" tool will weigh 700 tons and be able to handle combined loads of 1,250 tons. This procedure will be repeated consecutively to achieve nine sub-assemblies, which will be transferred into the Tokamak pit for the final sector assembly. The complete sub-assembly operation will take three months. Two sub-assembly tools will be manned concurrently (fed from one upending tool) to optimize assembly operations.

In all, 161 different types of custom tools will be required to assemble, lift and finally manoeuver ITER's supersized components. The tools will have loading capacities that vary from 500 tons for the "upending" tool that will turn vacuum vessel components from horizontal to vertical, to 1,500 tons for the heavy lifting tools used to lift the sub-assembled sectors into the Tokamak pit for final assembly and welding. There, the largest purpose-built tool, the in-pit assembly tool, will grasp all nine sectors together (3,800 tons) in order to align the vessel structure.

Following main assembly and alignment of the vacuum vessel, the second assembly phase—the installation of in-vessel components—can proceed with the specialized remote-handling devices.