A study on a non destructive examination system with an infrared thermography for CFC monoblock of divertor components

In the first set of ITER-divertor, the bottom segment of the inner and outer Vertical Target (VT) consists of the Carbon-Fiber-reinforced Composite (CFC) monoblock, the interlayer of the Oxygen-Free high-conductivity Cu (OFCu) and the cooling tube. In this part of the divertor, the capability to remove the high heat flux (HHF) up to 20MW/m2 meter has to be provided. Therefore, the method of quality estimation for the VT is one of key issues in procurement of the actual equipment. Non-Destructive Examination (NDE) with the infrared thermography is required as one of the quality tests to detect the overall defect in the CFC monoblock. The CFC monoblock heated at 95degC in steady state condition is rapidly cooled down to 5degC by a cold water flow. During the transient, the infrared thermography is performed via measuring the maximum temperature difference between the defect-free CFC monoblock and the test object. In this study, the thermographic examinations for VT Qualification Prototypes have been performed by the Facility of Infrared NDE for Divertor (FIND) built in the Japan Atomic Energy Agency. The FIND successfully detects the position and the magnitude of the overall defect in the CFC monoblock. Moreover, the profile of the maximum temperature difference in the FIND corresponds to that of the surface temperature of CFC in the HHF test in Russian Federation (RF). It indicates that FIND is able to predict the maximum temperature of CFC surface in HHF test. (author)