Development of ultrasonic testing equipment using electromagnetic acoustic tranducers

In nuclear power stations, in-service inspection (ISI) is conducted during the periodic outage. During ISI, ultrasonic testing (UT) is conducted, which requires preparations such as removal of the pipe coating, surface polishing, and mounting UT equipment to enhance the reliability of UT. Because these tasks are performed in a radiation field, it is important to simplify them and reduce the inspection period. For this reason, a new type of automatic UT equipment has been developed. This equipment consists of a noncontacting ultrasonic transducer, the electromagnetic acoustic transducer (EMAT), and the vehicle that scans EMAT. This paper describes the equipment and a test result performed using the equipment. It was confirmed that EMAT can detect 1.0-mm-high notch and that locating accuracy could be kept within +2 mm by using the vehicle. Further efforts will be made to improve the signal-to-noise ratio.