Proposal and Demonstration of Strategies for NDT of Conduit Tube of Cable in Conduit Conductors Used in ITER PF Coils

The Poloidal Field (PF) coils, made of superconducting Cable in Conduit Conductor (CICC), are important for keeping plasma inside the vacuum vessel of ITER Tokamak device. To ensure the safety of the PF coil, Non-Destructive Testing (NDT) has to be performed for each conduit tube of CICC, as it is the boundary of liquid Helium and supporting structure of the electromagnetic load. However, the complicated cross section shape of the PF conduit tube causes difficulty in its NDT. Aiming at solving the NDT problem of the PF conduit tube, two approaches are proposed and their validity is demonstrated in this paper. One is a hybrid strategy of the ultrasonic phased array and the eddy current array technology. The other is of the immersed ultrasonic testing method. The experimental results reveal that both approaches are promising for the NDT of ITER conduit tubes though the later one is more efficient.