LANL

One of the key concerns for safe disposal of spent nuclear fuel and radioactive wastes is the possibility of leaching of radionuclides and their migration to the environment. In order to support our laboratory studies and ones published earlier by other authors we analyzed a number of soils from contaminated sites. X-ray fluorescence maps and x-ray absorption fine structure spectra have been measured on U- and Pu-containing particles and bulk samples of soils from Chernobyl, McGuire AFB, Mayak, Hanford, and Los Alamos collected days to decades after their original deposition. In addition to the expected U(VI) and PuO_2+x speciation that are the most stable forms for U and Pu equilibrated with air and water in the laboratory, a number of other morphologies and compositions are found.