Characterization of hydrogen concentration in Zircaloy claddings using a low-frequency acoustic microscope with a PVDF/LFB transducer

Hydrogen embrittlement is one of the major mechanisms responsible for the degradation of ductility of Zircaloy cladding materials. Currently the characterization of hydrogen concentration (HC) very often relies on destructive methods that are time-consuming and costly. In this research, an ultrasound-based nondestructive evaluation (NDE) technique is reported for the determination of HC in Zircaloy claddings. This ultrasound-based NDE technique employs a low frequency acoustic microscope (AM) with a PVDF/LFB transducer and a Fourier-based signal processing technique. With this AM technique, a relation between the ultrasound wavespeed and the HC of Zircaloy is established. A resolution of HC measurements with the current technique is demonstrated to be better than 200 ppm. This NDE technique has been developed with an aim to have a better resolution and also to be potentially applied to poolside inspection.