Development of an ultrasonic test method for the non-destructive examination of ITER divertor components

Manufacturing of prototypical components by means of the two ENEA patented technologies, namely PBC (Pre-Brazed Casting) and HRP (Hot Radial Pressing) was successfully concluded in the frame of EFDA contracts. The successful results of the thermal fatigue testing performed at FE200 (200 kW electron beam facility, CEA/AREVA France) on these components are beyond ITER requirements (3000 cycles at 10 MW/m2 for 10 s on both CFC and W part, then 2000 cycles at 20/15 MW/m2 for 10 s on CFC/W part, respectively) and they have confirmed that the developed technologies are candidates for the manufacturing of monoblock divertor components. In order to reach these successful results a reliable non-destructive testing (NDT) procedure was set up. The chosen method was the ultrasonic water gap technique. This technique was chosen mainly for its reliability and because it can be applied during each step of the manufacturing route. The capability to detect any defect zones and to determine its actual position and extension was achieved by designing and assembling a suitable ultrasonic equipment. A specific software, developed at ENEA, is able to give all the required information. The NDT procedure was qualified by manufacturing several small samples containing reference defects of given size and position and by verifying the system capability to detect them. The destructive examination performed on some samples and on divertor vertical target prototypes has confirmed the reliability of the NDT equipment and procedure.