The central solenoid will be assembled from six cylindrical modules stacked one on top of the other. Weighing 110 tonnes and standing 2 metres high, each module is massive in its own right. But the modules are not the only heavy objects that will make up the overall structure.
In one corner of the ITER Assembly Hall, work has started on the central solenoid magnet tower. The first module now sits atop nine lower key blocks on a dedicated assembly platform. Five more modules will bring the tower to well over 20 metres (platform included), rivalling the height of a seven-storey residential building.
"We know we'll have to accommodate minor variations in module height, while targeting a specific height of the entire assembly," explains Carl Cormany, superconductor engineer in the Magnet Section. "And that's one of the jobs of this bottom plate. Each module is normally just over two metres tall and four metres in diameter. But for us, a deviation of 20 mm for the entire stack of six will be too much—and you can't predict the deviation until you've made the modules. A module might wind up five millimetres shorter or taller than you thought. Then the stacking process might result in further deviation. The fibreglass plates at the bottom and the top of our stack give us some capacity to adjust."
American Carl Cormany from ITER's Magnet Section works closely with the contractor team as it carries out the many assembly steps required on module one, including alignment, electrical connections, welding, and inspection and testing.
The first 110-tonne central solenoid module seen from below. US ITER is supplying seven modules (including one spare), the different elements of the central solenoid support (18 key blocks, 27 interior and exterior tie plates...), and the bespoke tools required for the assembly of the central solenoid magnet at ITER.