Progress on the ultrasonic testing and laser thermography techniques for NDT of tokamak plasma-facing components

• Main Authors: Cuixiang Pei, Haochen Liu, Jinxing Qiu, Tianhao Liu, Zhenmao Chen
• Format: Article
• Language: English
• Published: Elsevier 2019-05-01
• Series: Theoretical and Applied Mechanics Letters
• Online Access: http://www.sciencedirect.com/science/article/pii/S2095034919300327

ABSTRACT: During manufacturing and operation, different kinds of defects, e.g., delamination or surface cracks, may be generated in the plasma-facing components (PFCs) of a Tokamak device. To ensure the safety of the PFCs, various kinds of nondestructive testing (NDT) techniques are needed for different defect and failure mode. This paper gives a review of the recently developed ultrasonic testing (UT) and laser thermography methods for inspection of the delamination and surface cracks in PFCs. For monoblock W/Cu PFCs of divertor, the bonding quality at both W-Cu and Cu-CuCrZr interfaces was qualified by using UT with a focus probe during manufacturing. A noncontact, coupling-free and flexible ultrasonic scanning testing system with use of an electromagnetic acoustic transducer and a robotic inspection manipulator was introduced then for the in-vessel inspection of delamination defect in first wall (FW). A laser infrared thermography testing method is highlighted for the on-line inspection of delamination defect in FW through the vacuum vessel window of the Tokamak reactor. Finally, a new laser spot thermography method using laser spot array source was described for the online inspection of the surface cracks in FW. Keywords: Plasma-facing components, Ultrasonic testing, Laser thermography, Delamination, Surface crack