Statistical model for grain boundary and grain volume oxidation kinetics in UO{sub 2} spent fuel
- Lawrence Livermore National Lab., CA (USA)
- Battelle - Pacific Northwest Lab., Richland, WA (USA)
The Yucca Mountain Project of the US Department of Energy is investigating the suitability of a site in the unsaturated zone at Yucca Mountain, NV, for a high-level nuclear waste repository. Most of the waste will consist of UO{sub 2} spent fuel in Zircaloy-clad rods from nuclear reactors. If failure of both the waste containers and the cladding occurs within the lifetime of the repository, then the UO{sub 2} will be exposed to oxygen in the air and higher oxides of uranium may form. The oxidation state of the spent fuel may affect its dissolution behavior if later contacted by water. A model for the kinetics of spent fuel oxidation under repository-relevant condition is thus necessary to predict the behavior of the waste form for assessing the performance of the repository with respect to the containment of radionuclides. In spent fuel experiments, the UO{sub 2} oxidation front initially propagates along grain boundaries followed by propagation into grain volumes. Thus, the oxidation kinetics is controlled by two processes and the oxidation of spent fuel fragments will depend on the density and physical attributes of grain boundaries. With this in mind, concepts from statistical mechanics are used to define a density function for grain boundaries per unit volume per unit species in a spent fuel fragment. Combining the integral forms of mass conservation and this grain boundary density function, a model for the global rate of oxidation for a spent fuel fragment is obtained. For rapid grain boundary oxidation compared to grain volume oxidation, equations of the model are solved and results compared to existing data.
- Research Organization:
- Materials Research Society, Pittsburgh, PA (United States)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 138164
- Report Number(s):
- CONF-891129--
- Country of Publication:
- United States
- Language:
- English
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Spent fuel waste form characteristics: Grain and fragment size statistical dependence for dissolution response
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Related Subjects
CERAMOGRAPHY
DISSOLUTION
FUEL CANS
GRAIN BOUNDARIES
GRAIN SIZE
GROUND WATER
HIGH-LEVEL RADIOACTIVE WASTES
LEACHING
OXYGEN
PWR TYPE REACTORS
RADIOACTIVE WASTE DISPOSAL
RADIONUCLIDE MIGRATION
REACTION KINETICS
SITE CHARACTERIZATION
SPENT FUELS
TEMPERATURE DEPENDENCE
TIME DEPENDENCE
URANIUM OXIDES
US DOE
YUCCA MOUNTAIN
Yucca Mountain Project
ZIRCALOY