Ultrasonic non-destructive testing on CFC monoblock divertor mock-up

Non-destructive ultrasonic testing has been applied for the characterizatio n of joints by means of a polymer transducer. One of the advantages of the polymer transducer is flexibility in its shape and the possibility to insta ll multiple transducers in one probe, which can reduce the time for inspect ion. As a first step, the size effect of the transducer on the resolution a nd sensitivity was examined to detect the joint flaw Transducers with circu mferential angles of 5 degrees, 10 degrees and 30 degrees were tested. For this test a small divertor element with a drilled hole was prepared, which simulates a joint defect. The transducers with angles of 30 degrees could n ot characterize the size of the artificial joint flaw On the contrary, the size of the artificial defect was successfully detected with an accuracy of 90% by means of the transducers with angles of 5 degrees and 10 degrees. F rom the viewpoint of the sensitivity of the detection of the joint flaw, th e transducer with the angle of 10 degrees is appropriate because it could d etect the largest intensity of the reflected signal caused by the same arti ficial defect of the joint interface.