Influence of hydrogen on the oxygen solubility in Zircaloy-4

Despite the influence of hydrogen on the behavior of zirconium fuel cladding in many nuclear safety issues, the pseudo-binary Zircaloy-4 oxygen phase diagram still lacks of data, especially above 1000 degrees C. The aim of this study was to provide experimental data to better assess the influence of hydrogen on the oxygen solubility in Zircaloy-4. Homogenized two-phase Zircaloy-4 samples were elaborated from 300 to 1000 wppm pre-hydrided samples. Local distributions were characterized thoroughly using Electron Probe Micro-Analysis (EPMA) for oxygen and Elastic Recoil Detection Analysis (ERDA) for hydrogen. The data obtained in this work were included in the pseudo-binary Zircaloy-4 - oxygen phase diagram and have shown that hydrogen has limited influence on the alpha + beta -> beta transus. Regarding the alpha -> alpha + beta transus, no influence of hydrogen concentration in the alpha phase below 400 wppm was evidenced. (C) 2015 Elsevier B.V. All rights reserved.