Solubility and speciation results from over- and undersaturation experiments on neptunium, plutonium, and americium in water from Yucca Mountain region well UE-25p {number_sign}1
- Lawrence Berkeley Lab., CA (United States). Earth Sciences Div.
Solubility and speciation are important in understanding aqueous radionuclide transport through the geosphere. Results are compared from solubility and speciation experiments from oversaturation and undersaturation of {sup 237}NpO{sub 2{sup +}}, {sup 239}Pu{sup 4+}, and {sup 241}Am{sup 3+}/Nd{sup 3+} in a modified UE-25p-1 groundwater (from the Yucca Mountain region, Nevada, which is being investigated as a potential high-level nuclear waste disposal site) at 60 C and three pH values (6.0, 7.0, 8.5). In the oversaturation experiments, the solubility-controlling steady-state solids were identified and the speciation and/or oxidation states present in the supernatant solutions were determined. The characterized solids were then reintroduced into fresh solutions of the modified UE-25p-1 groundwater to approach the steady state from undersaturation. For the undersaturation experiments, the solubility-controlling steady-state solids were also identified and the speciation and/or oxidation states present in the supernatant solutions were determined. The Np solubility decreased with increasing pH in both the over- and undersaturation experiments. The steady-state concentrations from the two experiments agreed to within an order of magnitude. Pu concentrations from over- and undersaturation agree very well in the pH 6 and 7 experiments. The pH 8.5 oversaturation experiment resulted in a steady-state concentration one order of magnitude above its undersaturation counterpart. For the Am/Nd solutions, the pH 6 and pH 7 experiments resulted in equivalent steady-state concentrations from both over and undersaturation. The pH 8.5 oversaturation experiment was 100 times more soluble than its undersaturation counterpart. 48 refs.
- Research Organization:
- Los Alamos National Lab., NM (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-36
- OSTI ID:
- 171272
- Report Number(s):
- LA--13017-MS; ON: DE96003989
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
54 ENVIRONMENTAL SCIENCES
AMERICIUM COMPOUNDS
EXPERIMENTAL DATA
GROUND WATER
HIGH-LEVEL RADIOACTIVE WASTES
HYDROLOGY
NEODYMIUM COMPOUNDS
NEPTUNIUM OXIDES
PLUTONIUM COMPOUNDS
RADIOACTIVE WASTE DISPOSAL
RADIONUCLIDE MIGRATION
SATURATION
SITE CHARACTERIZATION
SOLUBILITY
TEST FACILITIES
VALENCE
WATER WELLS
YUCCA MOUNTAIN