Development of Materials and Manufacturing Technologies for Inter-coil Structure Components of the ITER TF Coil

Synopsis : For the ITER, 18 of the world’s largest Toroidal Field (TF) coils will be installed. The components that connect each TF coils are called Inter-coil structure components. Inter-coil structure components will be cooled down to 4 K and exposed to radiation during ITER operation. These components must ensure huge magnetic force while insulating the TF coils. In this study, the authors developed glass fiber reinforced plastic (GFRP) having a compressive strength property that minimizes degradation even in a radiation environment. The compressive strength of this GFRP is demonstrated to satisfy the required value. The authors also manufactured a customized Ni-based superalloy (Alloy718) bar from a standard product. The mechanical properties at room temperature and 4 K were obtained, and it was confirmed that these properties exceed the requirements. The Inter-coil structure components used for the interface require tight tolerance, so an alumina coating is applied on the surface of stainless steel. Next, the authors tested the alumina coating to see if it deteriorated after a thermal cycle. It is reported the optimizing the component manufacturing process requires an alumina coating and high dimensional accuracy. This views and opinions expressed herein do not necessarily reflect those of the ITER organization.