The ITER magnetic system includes the Toroidal Field (TF) Coils. To cope with the fatigue exercised on the TF Coils, and with the deformation resulting from the powerful magnetic fields, 3 Pre-Compression Rings (PCRs) will be placed on top of them and 3 below them. An extra set of 3 will be manufactured as spare and installed below the ITER machine in case there is a need in the future to replace the lower set.
In December 2016, F4E signed the contract with the French company CNIM for the procurement of 3 PCRs (with the option to produce 6 additional PCRs). 3 optional PCRs had been released in November 2018 so that CNIM is due to produce 6 PCRs and deliver them from May to November 2019.
This highly innovative process, proposed by CNIM and chosen by F4E, is based on a pultrusion technique that involves the manufacture of profiles of epoxy S2-glass. Each PCR is a manufacture by winding the flat pultruted profile (2mm thick and about 2800 m long) and utilizing an adhesive tape (0,12 mm thick) between layer to freeze the geometry. Finally, the PCR is machined to reach the required geometry tolerances. Each PCR will have a diameter of approximately 5 m, a cross-section of nearly 300 mm x 300 mm and will weigh approximately 3 T. The PCRs will finally be proof tested at 600MPa in hoop stress which corresponds to 1.5 time the operational hoop stress.
An extensive qualification phase has been released to prove that both materials and manufacturing technology can procure PCRs according to requirements.
This paper will describe the manufacturing processes, the results of the qualification phase and the status of the production.