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Reaction rates of unalloyed uranium with super heated steam at 160°–1400°C and 1 atm pressure have been determined by a thermogravimetric method. Up to 880°C the reaction follows a linear rate law with maximum rates at approximately 300° and 750°C. Above 880°C a parabolic rate law applies for the first 60–120 min, after which corrosion is linear; the oxide formed in the initial period gives protection to the underlying metal, and the subsequent linear rate is as low as that at about 200°C. X‐ray diffraction of the reaction product indicated that uranium dioxide was formed over almost the whole temperature range.

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Binary zirconium alloys and Zircaloy 2 have been corroded in water at 325°c with and without cathodic polarization. In some cases polarization can increase hydrogen uptake or reduce the protective character of the oxide films as assessed by capacity measurements. Alloying elements significantly influence both effects, but comparison of the alloys shows no systematic relation between their hydrogen uptakes and the loss of protective character of their films. Films formed in a previous period of unpolarized corrosion are damaged when polarized at 325° and at room temperature. Possible explanations of the effects of hydrogen and of alloying elements are suggested.