The construction of the ITER nuclear fusion reactor reached a new milestone with the integration of the fifth of the six modules that make up the central solenoid, one of the most critical components of the system. With a height of 18 meters and a total weight of 1000 tons, this huge superconducting electromagnet will be responsible for inducing and maintaining the pulsed current that passes through the plasma inside the tokamak, enabling its control and stability.
The assembly of the fifth module of the central solenoid.
The newly installed module, which is part of a stacked cylindrical structure, was placed on November 4 on top of the previously integrated modules. Each part weighs approximately 110 tons and requires millimetric alignment to ensure that the system works together. Due to its delicate construction, the process does not allow for errors or undue vibrations, and requires custom-designed lifting tools.
Specialized engineers and technicians used a set of customized mechanisms, including a circular frame with friction pads and special slings, to hold the modules without generating structural stresses. The laser metrology played a decisive role, since the components must be adjusted to an accuracy of less than one millimeter.
The placement of the upper solenoid modules presents additional complexities. The vertical extensions of the helium-cooled cables, which power the magnets with a current of 40 kA, must avoid any contact with the lifting structure during module lowering. Any friction would compromise the integrity of the system, so the maneuver requires extreme precision and coordination.
Carl Cormany, an engineer specializing in superconductivity, supervised the entire operation together with the team from the Chinese consortium CNPE, in charge of fabrication and assembly. Lifting platforms and monitoring cameras were key to ensuring the safety and efficiency of the procedure.
The last central solenoid module is scheduled to be installed in March 2026. Subsequently, a compression structure will be incorporated to apply downward force to the assembly, ensuring its structural integrity. The solenoid will remain on its platform until the tokamak pit is ready to receive the nine sectoral vacuum chamber modules.
Source and photo: ITER