A fitting situation for first ITER subassembly

September 1, 2021, 7:00AMNuclear News
Taken from above, this photo of the subassembly tool shows the complex system of alignment units used to slowly swing two toroidal field coils (bottom left and right) into position around the vacuum vessel sector. In the background, poloidal field coil #5 sits on the floor of the Assembly Hall, awaiting installation in the assembly pit in mid-September. (Photo: ITER)

Inside the ITER Assembly Hall, aided by a 20-meter-tall sector subassembly tool known as SSAT-2, the first of nine 40-degree wedge-shaped subassemblies that will make up the device’s tokamak is taking shape. On August 30, the ITER Organization announced that all the components of the first subassembly were in place on the SSAT-2. After the wings of the subassembly tool slowly close, locking two vertical coils in place around the outside of a vacuum vessel section that is already wrapped in thermal shielding, the completed subassembly will be ready for positioning in the ITER assembly pit in late October.

Time lapse: In April, following an eight-month preparatory campaign, the first vacuum vessel section from Korea was safely docked and later equipped with its corresponding thermal shield panels. By mid-August, two twin vertical coils from Japan were moved into the SSAT-2, ready to be locked around the vacuum vessel sector.

Each of the three massive components—the vessel sector and the two vertical coils—is as heavy as a fully loaded Boeing 747, according to ITER. When all adjustments are complete, the tool's wings will begin to move slowly and bring the coils closer to the vessel sector, eventually locking them into place. The process will be carried out a total of nine times to complete the ITER torus.

27 steps: Before the first vacuum vessel subassembly is lowered into the tokamak pit, 27 construction work packages, prepared by ITER Organization teams, must be completed by two assembly contractors. As of ITER’s August 30 press release, eight of 27 steps had been achieved.

Each work package addresses a specific task, which in turn is broken down by the contractors into detailed shop floor instructions. While one contractor is preparing the work floor in the tokamak pit and installing other components, the second contractor is tasked with preparing the subassembly.

This animation, created by Brigantium Engineering France for the ITER Organization, shows how the 1,200-metric ton subassembly will be transferred from the subassembly tool to its final destination inside the assembly pit.

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