Steam generator small bore piping socket weld inspection using the phased array ultrasonic technique

Abstract

As nuclear power plants age, the likelihood of failures in the small bore piping used in those plants caused by exposure to mechanical vibrations during plant operations increases. While small bore piping failures rarely cause plant shutdown, the management of small piping has been a keen area of interest since their repair or maintenance requires a reactor trip. Steam generator (SG) drain pipe socket welds are small diameter piping connections (nominal pipe schedule 3-4 inches) susceptible to mechanical vibration. SG drain pipe socket weld failures have caused coolant leakage. Therefore, more reliable inspection technologies for small bore piping need to be developed to detect problems at an early stage and prevent pipe failures. This research aims to improve the reliability and accuracy of small bore piping inspections through the design, manufacture and application of a new phased array ultrasonic testing technique and inspection system for SG drain line socket welds.

Compact Multi-Element Ultrasonic Transducer for Inspecting Split Pins in Nuclear Power Plants

“…Even if the transducer could reach these components, the ultrasonic beams could not cover the target inspection area because of the limited scanning space. Compact ultrasonic probes have emerged as a solution to this problem (Yoon et al, 2014;Erhard et al, 2001;Song et al, 2002;Kim et al, 2016b;Abdallah and Namgung 2018). Pajnić et al (Pajnić et al, 2009) developed a slim sword-like trinary probe with a pair of time-offlight diffraction (TOFD) transducers for the detection and sizing of circumferential and axial cracks in the 3 mm gap between the inner surface of the penetration nozzle and the thermal sleeve.…”