Metaschoepite, [(UO2)8O2(OH)12]·10H2O, and metastudtite, UO4·4H2O, are alteration phases anticipated in a spent nuclear fuel repository following the moist oxidation of UO2 on a geologic timescale. Dissolved concentrations and hence potential mobility of other radionuclides in the fuel, such as the neptunyl cation (NpO2+), will likely be determined by the extent of their partitioning into these U(VI) solids. 237Np is of particular interest due to its potential high mobility and long half-life (2.1 x 106 years.) In this study, metaschoepite has been precipitated and subsequently transformed to studtite in the presence of dissolved Np. The metaschoepite and studtite solids that formed initially contained
Revised: June 23, 2005 |
Published: June 1, 2005
Citation
Douglas M., S.B. Clark, J.I. Friese, B.W. Arey, E.C. Buck, and B.D. Hanson. 2005.Neptunium(V) Partitioning to Uranium(VI) Oxide and Peroxide Solids.Environmental Science & Technology 39, no. 11:4117-4124.PNNL-SA-44460.