Dissolution kinetics of UO sub 2 : Flow-through tests on UO sub 2. 00 pellets and polycrystalline schoepite samples in oxygenated, carbonate/bicarbonate buffer solutions at 25 degree C
The modelling of radionuclide release from waste forms is an important part of the performance assessment of a potential, high-level radioactive waste repository. Since spent fuel consists of UO{sub 2} containing actinide elements and other fission products, it is necessary to determine the principal parameters affecting UO{sub 2} dissolution and quantify their effects on the dissolution rate before any prediction of long term release rates of radionuclides from the spent fuel can be made. As part of a complex matrix to determine the dissolution kinetics of UO{sub 2} as a function of time, pH, carbonate/bicarbonate concentration and oxygen activity, we have measured the dissolution rates at 25{degrees} C of: (1) UO{sub 2} pellets; (2) UO{sub 2.00} powder and (3) synthetic dehydrated schoepite, UO{sub 3}.H{sub 2}O using a single-pass flow through system in an argon-atmosphere glove box. Carbonate, carbonate/bicarbonate, and bicarbonate buffers with concentrations ranging from 0.0002 M to 0.02 M and pH values form 8 to 11 have been used. Argon gas mixtures containing oxygen (from 0.002 to 0.2 atm) and carbon dioxide (from 0 to 0.011 atm) were bubbled through the buffers to stabilize their pH values. 12 refs., 2 tabs.
- Research Organization:
- Lawrence Livermore National Lab., CA (United States)
- Sponsoring Organization:
- DOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 6021724
- Report Number(s):
- UCRL-JC-107478; CONF-911109--3; ON: DE92002667
- Country of Publication:
- United States
- Language:
- English
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Atmospheric-- Radioactive Materials Monitoring & Transport-- (1990-)
ACID CARBONATES
ACTINIDE COMPOUNDS
BUFFERS
CHALCOGENIDES
CHEMICAL REACTION KINETICS
DISSOLUTION
ELEMENTS
ENERGY SOURCES
ENVIRONMENTAL TRANSPORT
FUELS
KINETICS
LEACHING
MASS TRANSFER
MATERIALS
MINERALS
NONMETALS
NUCLEAR FUELS
OXIDE MINERALS
OXIDES
OXYGEN
OXYGEN COMPOUNDS
PH VALUE
RADIOACTIVE MATERIALS
RADIOACTIVE MINERALS
RADIONUCLIDE MIGRATION
REACTION KINETICS
REACTOR MATERIALS
SCHOEPITE
SEPARATION PROCESSES
SPENT FUELS
THERMODYNAMIC ACTIVITY
URANIUM COMPOUNDS
URANIUM DIOXIDE
URANIUM MINERALS
URANIUM OXIDES
WASTE FORMS