The coupled current charge compensation model for zirconium alloy fuel cladding oxidation: I. Parabolic oxidation of zirconium alloys

A first principles oxidation model has been developed which can rationalize the kinetics observed in various zirconium alloys using a unified theoretical approach, which predicts that space charges in the oxide have a major impact on oxidation kinetics. As a first development, the parabolic oxidation of Zr-0.4Nb alloy is fitted by the model assuming that space charges in the oxide are compensated by Nb ions. The model quantitatively reproduces the oxidation kinetics using physically significant parameters. XANES examinations show that there are enough aliovalent Nb ions in the oxide layer to verify oxide electroneutrality as predicted by the model.