Roles of Radiolytic and Externally Generated H2 in the Corrosion of Fractured Spent Nuclear Fuel

A 2-D model for the corrosion of spent nuclear fuel inside a failed nuclear waste container has been modified to determine the influence of various redox processes occurring within fractures in the fuel. The corrosion process is driven by reaction of the fuel with the dominant a radiolysis product, H2O2. A number of reactions are shown to moderate or suppress the corrosion rate, including H2O2 decomposition and a number of reactions involving dissolved H-2 produced either by a radiolysis or by the corrosion of the steel container vessel. Both sources of H-2 lead to the suppression of fuel corrosion, with their relative importance being determined by the radiation dose rate, the steel corrosion rate, and the dimensions of the fractures in the fuel. The combination of H-2 from these two sources can effectively prevent corrosion when only micromolar quantities of H-2 are present.