The response of the corrosion potential of a UO2 electrode to oxidants (H2O2, O-2) produced by the alpha radiolysis of water has been measured in a thin-layer electrochemical cell. This cell allows the electrode to be brought within similar to 25 mu m of a gold-plated alpha source, thereby ensuring the uniform distribution of radiolytic oxidants in the aqueous solution filling the gap. The kinetics of water radiolysis, coupled with the surface-catalyzed decomposition of H2O2 and diffusive transport of radiolytic species out of the electrode-source gap, was modeled using a finite difference description of the cell and the commercial numerical integration software, Facsimile. Using this approach, the mechanism of UO2 corrosion in the presence of alpha radiolysis was shown to be dominated by reaction of the fuel with radiolytically produced H2O2. To explain the results, two surface-catalyzed H2O2 decomposition processes were invoked: one with H-2 to produce H2O, and a second process leading to the production of O-2 and H2O. For sufficiently high alpha source strengths, the fuel behavior becomes redox-buffered, i.e., independent of alpha source strength, due to the presence of a corrosion product deposit. (c) 2005 The Electrochemical Society.