Corrosion Behavior of Uranium Dioxide in Alpha Radiolytically Decomposed Water

The response of the corrosion potential of a electrode to oxidants 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 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 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 corrosion in the presence of alpha radiolysis was shown to be dominated by reaction of the fuel with radiolytically produced . To explain the results, two surface-catalyzed decomposition processes were invoked: one with to produce , and a second process leading to the production of and . 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.