Non-Destructive Examination Method for the ITER Toroidal Field Conductor Terminations

An electric Non-Destructive examination method has been developed in order to inspect the ITER toroidal field (TF) terminations at room temperature and give an indication of the joint performance during manufacturing, thus reducing the risks related to high-resistance joints during operation. The inspection method injects 200 A in a TF conductor close to the termination and collects the current in a scanning head which contains 61 voltage taps and 15 return electrodes. The voltage readings along and across the scanning head are used to evaluate the resistance profile along the termination. A series of mock-up samples has been prepared reproducing the geometry of the ITER TF terminations and introducing controlled defects in order to validate the inspection technique. The results of the inspection of these artificially degraded termination samples are presented, showing that large defects can be detected at room temperature if the voltage reference is in direct contact with the strand bundle.