Embrittlement of Zr−2.5%Nb pressure tubes from CANDU nuclear reactors has recently become a concern in the Canadian nuclear industry. While a full understanding of the mechanisms involved has not yet been achieved, it is known that hydrogen/deuterium, liberated through oxidization of the tube’s inner surface, is absorbed into the metal where it eventually precipitates out as weak, brittle hydride platelets. Knowledge of the nature and extent of oxide formation may thus give indications about the degree of hydrogen uptake and embrittlement in the tubes. In particular, a reliable, nondestructive technique for determining the thickness and integrity of these oxide layers is needed. Theoretically, such an evaluation is possible using ultrasonic spectroscopy.