An Ultrasonic Technique for the Testing of Plates Embedded in Concrete with a Multielement Probe

An ultrasonic testing technique was selected for testing the reactor containment vessel plate of a pressurized water reactor plant that was embedded in concrete. The technique used a transducer with piezoelectric elements to perform the testing on the reactor containment vessel plate. A shear horizontal wave transducer with a large and low-frequency active element composed of three parallel-connected active elements with a refractive angle of 90° was developed for testing. It was deployed for effective detection of surface thinning by corrosion and for minimizing dispersion of ultrasonic waves from steel plates to concrete. A multielement transducer with a multichannel pulser and receiver was also constructed to improve the capability of propagation over long distances. The steel plate was covered with a layer of 200 mm thick concrete on both surfaces to simulate a plate embedded in concrete. Two edges on opposite sides were left uncovered to support the mounting of the transducer.