February 14, 2022
The two workers on the cherry picker had spent more than one hour slowly turning the three turnbuckles attached to the straps that held the load. Millimetre by millimetre they had adjusted the straps' length so that, once lifted from its frame, the 110-tonne component would be perfectly balanced and the lift perfectly vertical. Eventually, the electrical motors on the double overhead crane started purring and the load began to lift. Out of the whole operation, performed on Thursday 10 February, this was the most delicate moment: any contact with the fragile electrical connections on the central solenoid module would have had severe consequences. And the clearance was very small.
The central solenoid module is one of six more or less identical elements which, once assembled, will form the "beating heart" of the ITER Tokamak. Procured by the United States, the 1,000-tonne central solenoid has been dubbed "the most powerful magnet in the world," capable of lifting an aircraft carrier out of the water. The first module was delivered to ITER in September 2021 and the second one month later.
Like the 18 toroidal field coils that surround the vacuum vessel, the central solenoid's superconducting windings, and the protruding "lead" that feeds the high-voltage, are made of niobium-tin, a compound that, contrary to the niobium-titanium of the poloidal field coils, is quite brittle. This relative fragility explains the extreme care that went into the lift operation's preparation and execution.
Having travelled almost the whole length of the Assembly Hall, the module and its lifting frame were eventually lowered and positioned on a simple "table" where months-long tests will be performed. The module's instrumentation, sensors and superconducting joints need to be carefully checked and tested before it is transferred to the bespoke assembly platform nearby.
Lifting, stacking and assembling the six modules into a 18-metre high, 1,000-tonne magnet will require a set of high-precision tools also procured by US ITER and already delivered. The total value of the assembly tooling contracts is in excess of USD 10 million.
Once finalized, the ITER central solenoid will be placed at the very centre of the Tokamak pit where the central column (a temporary assembly tool) presently stands.
Source: ITER Organization
Last Updated: March 28, 2022 - 12:24 pm