Ultrasonic studies on iter divertor and first wall prototype modules

Blanket and divertor components of ITER are complicated in design and reliable reactor operation sets special requirements on applied manufacturing methods and on quality and integrity assessment methods. R&D programmes have been implemented to develop suitable nondestructive testing method as a part of ITER Primary First Wall and Divertor component manufacturing programmes. The suitability of several nondestructive testing methods have been evaluated i.e. ultrasonic inspection, eddy current, X-ray, infrared thermography and leak testing during different manufacturing stages as a quality assurance method and after thermal fatigue tests as an integrity assessment method. In this study ultrasonic methods have been applied to evaluate structural integrity of several ITER Primary First Wall and Divertor Vertical Target mock-ups before and after thermal fatigue and high heat flux tests. The techniques used were leaky Rayleigh wave and longitudinal wave reflection techniques. The applicability of ultrasonic methods was evaluated by using small scale mock-ups with artificial manufacturing defects on different interfaces. In addition to outer surfaces of the mock-ups several dissimilar metal planar and tubular interfaces have been examined i.e. Be and Cu surfaces and Be/Cu, Cu/Cu, Cu/Stain-less steel, W/Cu and CfC/Cu interfaces. The ultrasonic examinations were carried out before and after cyclic thermal loading for ITER Primary First Wall mock-ups up to 4 MWm-2 and for ITER Divertor Vertical Target mock-up up to 15 MWm-2. The leaky Rayleigh wave technique was used to detect surface defects and interface defects in different joints. The longitudinal wave reflection was used only for interface defects. New probes were designed for inspection tasks. The NDT methods are compared briefly in this paper as well as the accuracy of detecting defects with ultrasonic testing methods.