Enerpac to lift fusion magnet

When the ITER fusion tokamak vacuum sectors are completed in 2024, nine Enerpac hydraulic cylinders will lift an 11 metre diameter, 320 tonne circular poloidal magnet (PF6) into position.

To access the magnet, each customised HCL1008 hydraulic cylinder is connected to an EVO synchronised lifting system

The cylinders are currently pre-installed at the bottom of the machine and will eventually move the magnet into place at the base of the tokamak.

The PF6 magnet is situated at the bottom of the vessel on temporary supports while the ITER tokamak is constructed above it, after which it will be completely enclosed and unreachable by crane.

To access the magnet, each customised HCL1008 hydraulic cylinder is connected to an EVO synchronised lifting system, enabling each of the nine lifting points to be monitored and controlled by a single operator.

Enerpac says that the EVO pump has highly accurate positional control, to within 1 millimetre, between lagging and leading cylinders, and includes built-in warning and stop alarms to improve safety.

In addition, the PF6 lifting EVO pump features a flow control valve to reduce the lifting speed even more. During the staging lifts, the custom single acting cylinders with spring return will act as locking pins, to hold the position of the magnet.

The cylinders’ 200 millimetre stroke will allow stack beams to be inserted beneath the PF6 ring. After lowering the magnet onto the stack beams, the cylinders will be repositioned on the next level of stack beams, and the process repeated until the magnet is finally bolted to the tokamak.

“We are faced with a challenging problem: how to lift the PF6 ring to its final position and bolt it to the tokamak structure within tight space constraints and without access to a crane,” said Nello Dolgetta, of the ITER Magnet Section team, in charge of the operation.

“To raise the PF6 ring by 2 metres, we are performing a synchronised lift using the Enerpac single acting locknut cylinders and EVO system to provide a safe and secure lift operation.

“Early trials with a dummy load were very successful.”

New fusion technology

The ITER tokamak hosts the fusion reaction in which plasma particles collide and release energy at temperatures up to 150M degrees C. To prevent the plasma touching any of the tokamak walls and disrupting the reaction, magnetic confinement is used with a combination of large circular toroidal and poloidal magnets.