Uranium-(VI) phases are the primary alteration products of the UO{sub 2} in spent nuclear fuel and the UO{sub 2+x}, in natural uranium deposits. The U(VI)-phases generally form sheet structures of edge-sharing UO{sub 2}{sup 2+} polyhedra. The complexity of these structures offers numerous possibilities for coupled-substitutions of trace metals and radionuclides. The incorporation of radionuclides into U(VI)-structures provides a potential barrier to their release and transport in a geologic repository that experiences oxidizing conditions. In this study, natural samples of UO{sub 2+x}, have been used to study the U(VI)-phases that form during alteration and to determine the fate of the associated trace elements.

Citation: Deditius, A.P., Utsunomiya, S., Ewing, R.C. United States. Yucca Mountain Project. Alteration of U(VI)-Phases under Oxidizing Conditions.Washington, D.C.: Department of Energy, 2006.

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