Non-destructive characterization of hydrogen concentration in zircaloy by a low-frequency acoustic microscope

Hydrogen embrittlement due to the uptake of hydrogen into zircaloy is one of the major factors in the degradation of ductility for the zircaloy cladding. 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 zircalloy tubes. This ultrasound-based NDE technique employs a low-frequency PVDF/LFB transducer operated in a z-scan mode and a Fourier-based signal processing technique. With this technique, a relation between the ultrasound wavespeed and the HC in zircaloy is established. A resolution in measuring the HC with the current technique is demonstrated to be better than 300 ppm.