Breakaway of Zirconium Oxide Film After High Temperature Oxidation in Steam - 21223

Zirconium is considered a suitable material for nuclear cladding due to its mechanical and chemical properties. The constant interaction between fuel rods and steam is considered one of the most relevant subjects in the nuclear industry. This research oxidized zirconium metal in steam at 800, 900, 1000, and 1100 deg. C for 1 hour to find out the lowest temperature to reach breakaway. Characterization of the oxide film and kinetics of reaction showed evidence of breakaway at 1100 deg. C since the surface cracks clearly extended through the oxide, while the calculated rate law and rate constant were 1.75 and 1.7078 mg^1.75/min, respectively.. The oxide film after steam oxidation at 800 deg. C showed indications of a protective oxide film, while the rate law followed a cubic behaviour. The oxide films showed signs of a non-protective oxide scale after isothermal oxidations at 900 and 1000 deg. C, however breakaway was not present. (authors)