With increased burnups and longer life times in nuclear reactors uniform corrosion of zirconium alloy nuclear fuel cladding and the associated hydrogen pick-up can become a life-limiting degradation mechanism in existing and advanced light water reactors, since the ingress of hydrogen and precipitation of hydrides can cause cladding embrittlement. Thus, it is of great interest to limit cladding embrittlement by decreasing overall corrosion and/or by decreasing the amount of hydrogen ingress for a given corrosion rate.
Despite extensive research, the mechanisms of hydrogen pickup and especially the influence of the alloy composition and microstructure on hydrogen pickup fraction are not at all well understood. In addition, there is evidence that the hydrogen pickup fraction may vary during the corrosion process, such that different values occur at different stages of oxide film growth. Part of the difficulty in developing mechanistic understanding of hydrogen pick-up is that accurate and precise measurements of hydrogen pick-up during corrosion are difficult to obtain. The purpose of this study is to demonstrate the use of Cold Neutron Prompt Gamma Activation Analysis (CNPGAA) to investigate the variations of hydrogen pickup fraction with alloy composition, corrosion time and alloy microstructure.
- A. Couet, A. T. Motta, R. J. Comstock, and R. L. Paul, “Cold neutron prompt gamma activation analysis, a non-destructive technique for hydrogen level assessment in zirconium alloys,” Journal of Nuclear Materials, vol. 425, no. 1-3, pp. 211-217, 2012.