Neptunium concentrations in solutions contacting actinide-doped glass
To help predict concentrations of neptunium leached from nuclear waste repositories in geologic environments, the solubility of neptunium in a neptunium-doped borosilicate glass, which simulates a high-level waste glass, was investigated. The concentrations of neptunium in solutions contacting the crushed doped glass were found to be controlled by a neptunium solid phase that is similar to crystalline(c) NpO/sub 2/ in solubility. Thus, the maximum concentration of the neptunium leached from this waste form can be predicted from the solubility of NpO/sub 2/(c). This conclusion is based on similar neptunium concentrations in solutions contacting neptunium-doped glass, neptunium-doped glass plus NpO/sub 2/(c), and NpO/sub 2/(c) alone, under controlled redox potentials and a range of pH values. The quinhydrone used in this study was found to be a very effective redox buffer (the approximate pe + pH = 11.8). The predictions based on the thermodynamic data and the solvent extraction tests showed Np(V) to be the primary oxidation state in solution.
- Research Organization:
- Pacific Northwest Laboratory P.O. Box 999, Richland, Washington 99352
- OSTI ID:
- 6062008
- Journal Information:
- Nucl. Technol.; (United States), Journal Name: Nucl. Technol.; (United States) Vol. 58:1; ISSN NUTYB
- Country of Publication:
- United States
- Language:
- English
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ACTINIDE COMPOUNDS
ACTINIDES
BOROSILICATE GLASS
CHALCOGENIDES
CHEMICAL REACTIONS
CONCENTRATION RATIO
DISSOLUTION
DOPED MATERIALS
ELEMENTS
EXTRACTION
FORECASTING
GLASS
LEACHING
MATERIALS
METALS
NEPTUNIUM
NEPTUNIUM COMPOUNDS
NEPTUNIUM OXIDES
OXIDATION
OXIDES
OXYGEN COMPOUNDS
PH VALUE
PHYSICAL PROPERTIES
REDOX POTENTIAL
SEPARATION PROCESSES
SOLUBILITY
SOLVENT EXTRACTION
THERMODYNAMIC PROPERTIES
TRANSURANIUM COMPOUNDS
TRANSURANIUM ELEMENTS