SYMPOSIA PAPER Published: 01 January 1987
STP28139S

Oxidation of Zircaloy-4 in Steam at 1300 to 2400°C

Source

The oxidation kinetics of Zircaloy-4 in steam have been extended to 2400°C. Growth of the ZrO2 and α-Zr(O) layers display parabolic behavior over the entire temperature range studied; however, a discontinuity in the oxidation kinetics above 1510°C causes rates to increase above those previously established by the Baker-Just relationship. This increase coincides with the tetragonal-to-cubic phase transformation in ZrO2−x. No additional discontinuity in the oxide-growth rate is observed upon melting of Zr(O). The effects of temperature gradients have also been taken into account, and corrected values representative of near-isothermal conditions have been computed.

Experiments have been performed in steam-hydrogen mixtures at 1565 and 1815°C. Concentrations of hydrogen up to 90 mol% have no effect on the oxidation kinetics. The rate-controlling factor appears to be the available flux of oxygen atoms incident to the reaction surface and is not dependent upon hydrogen content.

Author Information

Prater, JT
Pacific Northwest Laboratory, Richland, WA
Courtright, EL
Pacific Northwest Laboratory, Richland, WA
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Details
Developed by Committee: B10
Pages: 489–501
DOI: 10.1520/STP28139S
ISBN-EB: 978-0-8031-5004-1
ISBN-13: 978-0-8031-0935-3