Development of ultrasonic waveguide techniques for under-sodium viewing

• Published in: NDT & E international : independent nondestructive testing and evaluation Vol. 49; pp. 71 - 76
• Main Authors: Wang, Ke, Chien, Hual-Te, Elmer, Thomas W., Lawrence, William P., Engel, David M., Sheen, Shuh-Haw
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.07.2012; Elsevier
• Subjects: Applied sciences; Cross-disciplinary physics: materials science; rheology; Echoes; Energy; Energy. Thermal use of fuels; Exact sciences and technology; Fission nuclear power plants; Imaging; In-service inspection; Installations for energy generation and conversion: thermal and electrical energy; Materials science; Materials testing; Physics; Prototypes; Sodium; Sodium-cooled fast reactor; Ultrasonic; Ultrasonic testing; Under-sodium viewing; Viewing; Waveguide; Waveguides; Under-sodium viewing; Sodium-cooled fast reactor; In-service inspection; Waveguide; Ultrasonic; Liquid sodium; Corrosive environment; Ultrasound imaging; Hostile environment; High temperature; Background noise; In service inspection; Nuclear reactor; Prototype tests; Ultrasonic imaging; Time of flight method; High sensitivity; Ultrasonic control; C scan; Fast reactor; Viewing system; Acoustic image; Ultrasound; Mode conversion
• ISSN: 0963-8695; 1879-1174
• DOI: 10.1016/j.ndteint.2012.03.006

An ultrasonic imaging system based on waveguide techniques was developed to provide in-service inspection of reactor core of a sodium-cooled fast reactor (SFR) and potential applications in other hostile environments. By using the ultrasonic waveguide techniques, we overcome the major technical challenge in developing an under-sodium viewing (USV) system that can withstand the high-temperature and corrosive environment. The chosen design of the prototype waveguide (WG) is a hybrid of bundle and spiraled-sheet WG. The prototypes show high detection sensitivity with minimal background noise by effectively reducing spurious echoes and mode conversions. Tests on prototype waveguide transducers were conducted in liquid sodium up to 340°C (650°F). C-scan images of the targets were successfully developed from both time-of-flight and amplitude variations of the reflected echoes. The ultrasonic waveguide imaging system demonstrates a capability of detecting defects with 1mm width and 0.5mm depth under molten sodium. ► Developed a novel ultrasonic waveguide technique for under-sodium imaging. ► Reduced the spurious echoes and mode conversions effectively. ► Demonstrated the imaging capability in molten sodium up to 650°F successfully. ► Achieved defects detection with lateral resolution of 1mm and vertical resolution of 0.5mm.