Numerical modeling of oxygen diffusion in the wall thickness of Low-Tin Zircaloy-4 fuel cladding tube during high temperature (1100-1250 °C) steam oxidation

A new numerical tool has been developed by coupling the diffusion code EKINOX (Estimation Kinetics Oxidation) and the thermodynamic database ZIRCOBASE using TQ(ThermoCalc program interface). The aim of this tool is to calculate the oxygen diffusion during oxidation of Zr based alloys. The simulation results of the oxide growth kinetics and the induced oxygen diffusion profiles in the [1100-1250 degrees C] temperature range, at different times, are presented and compared to previous experimental results. An estimation of the diffusion coefficient in the alpha phase is deduced from this comparison. The results are discussed in comparison to previous models based on an analytical treatment and the influence of the choice of the thermodynamic data set on the final oxygen diffusion profile is explored. Finally, it is shown that the present modeling is able to predict quite accurately the critical oxidation time corresponding to the overall ductile-to-brittle transition of the high temperature (HT) oxidized clad. (C) 2010 Elsevier B.V. All rights reserved.