Effects of oxygen partial pressure on oxidation of Zircaloy

Abstract

The effects of oxygen partial pressure on the oxidation of Zircaloy-4 were examined at 773 K under the oxygen partial pressure between 0.1 and 2 × 10 −5 MPa to study the oxidation behavior of spent fuel during dry storage. The oxidation rate at first obeyed a cubic rate law, and changed to obey a linear rate law at almost the same weight gains even at different oxygen partial pressures. The oxidation rate during posttransition period showed p O 2 0.15 dependence. The dependency of the oxidation rate in the posttransition region agreed with the results of the oxygen diffusion coefficient in zirconium oxide measured by Keneshea and Douglass. Degradation of the protective oxide film of Zircaloy-4 under low oxygen partial pressures was not observed within the oxygen partial pressure range examined. The results of this experiment showed that the oxidation rate in air can be adopted to estimate the cladding oxidation rate during dry fuel storage in air and under low oxygen partial pressures.