Toroidal field coils
Two make a pair
6 Jul 2020
One of the essential "building blocks" of the ITER Tokamak is the pre-assembly of two toroidal field coils, one vacuum vessel sector and corresponding panels of thermal shielding. Combining these different components into one ~ 1,200-tonne single assembly will be the task of the twin sector sub-assembly tools (SSATs). The operation will be repeated nine times (for nine vacuum vessel sectors) and involve 18 toroidal field coils.
Travelling along the 104-kilometre-long "ITER Itinerary," convoys transporting highly exceptional loads, such as this toroidal field coil from Japan (TF13), cross through 16 municipalities (here, Saint-Estève Janson).
One by one, the components for the first vacuum vessel pre-assembly are being delivered to ITER. Sets of thermal shielding from Korea began arriving in October last year; toroidal field coil #12, procured by Japan, reached the ITER site on 25 April; and its "partner"—toroidal field coil #13, also from Japan—was received last Friday 3 July. As for the 440-tonne vacuum vessel sector that will be paired to the two Japanese coils—Sector #6—it left the port of Busan, Korea, on 28 June and is expected to reach Marseille industrial harbour before the end of July.
In the Assembly Hall, the major tools are standing ready: the upending tool will be used to raise the heaviest elements of pre-assembly from horizontal to vertical; the overhead cranes will transport the vacuum vessel sectors and toroidal field coils in turn to the sector sub-assembly tools; and the sector sub-assembly tools will support all elements during assembly.
Stepping up on the sidewalk
The transport frame adds close to 200 tonnes to the weight of the coil proper and close to one metre to its width. As a consequence, the convoy sometimes needs to step up onto the sidewalk, brushing by the overhanging vegetation in the process.
A four-night journey
Travelling at speeds ranging from 2 to 17 kilometres per hour, convoys cover the distance between Berre, on the shores of the inland sea Étang-de-Berre, and the ITER site in four nights.
A pause under the moon
Halfway to its destination the convoy makes a 45' pause to provide drivers and operators a moment of rest. Here, on the third night of the journey from Marseille harbour to ITER, the convoy is stationed near the thruway entrance in Pertuis.