The Determination of Local Corrosion Kinetics Using Scanning Electrochemical Microscopy

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Heming He
Z. Qin
P.G. Keech
J.J. Noël
Z.F. Ding
D.W. Shoesmith

Abstract

The focus of this research is the local corrosion behaviour of a number of hyper-stoichiometric UO2+x electrodes. SECM images and SECM approach curves have been recorded on four well characterized UO2+x specimens with x values of 0.002, 0.011, 0.05, and 0.1 under natural corrosion conditions. Comparison of experimental approach curves to numerically simulated approach curves allowed a determination of the “standard” rate constant for the cathodic reduction of the mediator on the UO2+x surface. Since this reaction is coupled to the anodic dissolution of the UO2+x, it is a measure of fuel corrosion rate. The results suggest that corrosion could be enhanced in non-stoichiomnetric grain boundaries in the fuel.

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