Aqueous corrosion of aluminum-based nuclear fuel

Some aluminum-based nuclear fuels may eventually be disposed in a federally approved repository. As part of the qualification process, experiments are being conducted on uranium-aluminide (UAlx) fuels to describe corrosion under conditions that could arise during permanent storage. Under the action of intermittent drips of well water at 90 °C, a thin silica-substituted hydrous aluminum oxide gel layer forms over the fuel surface. The exposed fuel oxidizes to produce hydrated aluminum and uranyl oxyhydroxide compounds. In accordance with theory and previous observations with UO2 fuels, the sequence of alteration products progressed from uranium oxides to uranyl oxyhydroxides such as dehydrated schoepite and becquerelite phases although at a rate that was much faster than for UO2 fuels. The release or leaching of uranium from the fuel was 0.97 mg U/m2/d at a pH of 8.4±0.8.