ENEA has been working on improving the ultrasonic scanning technique of Plasma Facing Units (PFUs) components for many years, obtaining increasingly accurate and easy to interpret results. The first tests were performed on small mock-ups and, due to the geometry of the component, tests were performed from inside the tube. The first issue to solve was the reduced pipe thickness and the need to direct the ultrasound beam orthogonally to the tube surface. The choice of the correct probe characteristics and its particular shape solved this issue. Subsequently, the problem of a scan along a curved tube had to be addressed. Therefore, a special probe holder, able to follow the curvature placed at the end of a flexible shaft, was designed. The definition of more stringent acceptance criteria for the plasma facing components required to increase the scanning resolution. Defect detection and sizing were improved up to 0.5 mm by working on automatic system and data analysis software. The increasing of the sample sizes up to full-scale prototype for pre-production, led to the necessity to improve speed of the scanning without losing resolution. At this point, the scan along generatrix was discarded to pass to a helical path. In this work, the system created and patented in ENEA laboratories, for scanning full-scale Inner Vertical Target PFU prototypes of ITER, is illustrated. Test results in terms of resolution and defects sizing are shown.
|Titolo:||ENEA ultrasonic test on plasma facing units|
|Data di pubblicazione:||2019|
|Appare nelle tipologie:||1.1 Articolo in rivista|