Uranium geochemistry in soil and groundwater at the F and H seepage basins
For 33 years, low activity liquid wastes from the chemical separation areas at the U.S. Department of Energy`s Savannah River Site were disposed of in unlined seepage basins. Soil and associated pore water samples of widely varying groundwater chemistries and contaminant concentrations were collected from the region downgradient of these basins using cone penetrometer technology. Analysis of samples using inductively coupled plasma - mass spectrometry has allowed the investigation of uranium partitioning between the aqueous phase and soil surfaces at this site. The distribution of uranium was examined with respect to the solution and soil chemistry (e.g., pH, redox potential, cation and contaminant concentration) and aqueous-phase chemical speciation modeling. The uranium soil source term at the F- and H-Area Seepage Basins (FHSB) is much smaller than has been used in previous modeling efforts. This should result in a much shorter remediation time and a greater effectiveness of a pump-and-treat design than previously predicted. Distribution coefficients at the (FHSB) were found to vary between 1.2 to 34,000 1 kg{sup {minus}1} for uranium. Differences in sorption of these elements can be explained primarily by changes in aqueous pH and the associated change in soil surface charge. Sorption models were fit directly to sorption isotherms from field samples. All models underestimated the fraction of uranium bound at low aqueous uranium concentrations. Linear models overestimated bound uranium at locations where the aqueous concentration was greater than 500 ppb. Mechanistic models provided a much better estimate of the bound uranium concentrations, especially at high aqueous concentrations. Since a large fraction of the uranium at the site is associated with the low-pH portion of the plume, consideration should be given to pumping water from the lowest pH portions of the plume in the F-Area.
- Research Organization:
- Westinghouse Savannah River Co., Aiken, SC (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC09-89SR18035
- OSTI ID:
- 10194263
- Report Number(s):
- EPD-SGS--94-307; ON: DE95002688
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
053002
11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE WASTES FROM NUCLEAR FACILITIES
54 ENVIRONMENTAL SCIENCES
540230
99 GENERAL AND MISCELLANEOUS
990200
GEOCHEMISTRY
LIQUID WASTES
LOW-LEVEL RADIOACTIVE WASTES
MATHEMATICAL MODELS
MATHEMATICS AND COMPUTERS
RADIOACTIVE EFFLUENTS
RADIOACTIVE MATERIALS MONITORING AND TRANSPORT
RADIOACTIVE WASTE DISPOSAL
RADIONUCLIDE MIGRATION
SAVANNAH RIVER PLANT
SOIL CHEMISTRY
URANIUM
WASTE DISPOSAL AND STORAGE
WASTE-ROCK INTERACTIONS