Zirconium alloys are used as fuel cladding in pressurised and boiling water nuclear reactors. As such these materials are exposed to a large number of environmental factors that will promote degradation mechanisms such as oxidation. At high burn-ups, i.e. extended service life, oxidation and the associated hydrogen pick-up can be a limiting factor in terms of fuel efficiency and safety. The oxidation kinetics for many zirconium alloys are cyclical, demonstrating a series of approximately cubic kinetic curves separated by transitions [1–5]. These transitions are typified by a breakdown in the protective character of the oxide and are potentially linked to a number of mechanical issues. Understanding how these issues influence oxidation is a key to developing a full mechanistic understanding of the corrosion process.
