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This interim progress report describes new experimental data collected from October 1, 1992 through May 31, 1993 as part of the Characterization Task of the Uranium in Soils Integrated Demonstration of the Office of Technology Development, Office of Environmental Restoration and Waste Management of the United States Department of Energy. X-ray absorption and optical luminescence spectroscopies have been used to analyze the uranium remaining in contaminated soils from the Fernald site after these samples were treated by various decontamination technologies under development within this Integrated Demonstration. The treatment technologies included soil washes with carbonate, citrate, Tiron, and Tiron/dithionite mixtures. The effectiveness of these procedures is discussed in a separate report from the Decontamination Task group. The characterization results indicate that following the application of all of these treatment strategies the uranium remaining in the soil is still best characterized as being primarily in the hexavalent oxidation state. However, for the A-series soils from the Incinerator Area, the speciation of this remaining uranium is different than seen previously based on the x-ray absorption data. The luminescence data for these treated soils also demonstrate that there is a decrease in size and quantity of the particulate hexavalent uranium that gives rise tomore » the structured green emission. Thus, all treatment technologies do seem to generate a more dispersed, finer-grained form of uranium. For several treated samples a characteristic luminescence signal was found indicative of a schoepite phase of uranium. New results are also reported for untreated Fernald soil samples and reference uranium mineral phases.« less |
