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U.S. Department of Energy
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Technical test description of activities to determine the potential for spent fuel oxidation in a tuff repository

Technical Report ·
OSTI ID:59371
The potential change in the oxidation state of spent fuel during its residence in a repository must be known to evaluate its radionuclide retention capabilities. Once the container breaches, the spent fuel in a repository sited above the water table will be exposed to a moist air atmosphere at low temperatures. Thermodynamically, there is no reason why the fuel should not oxidize to a higher oxidation state under these conditions, given enough time. Depending on the rate of oxidation, higher oxides with potentially higher leach rates may eventually form or the cladding may even split open. If either of these oxidation effects occurs, the ability of spent fuel to retard radionuclide migration will be reduced. A technical test description is presented to study spent fuel oxidation at low temperatures characteristic of the post-container breach period and at high temperatures in a moist inert atmosphere characteristic of a sealed container with waterlogged fuel, early in the repository life. The approach taken will be to perform tests and evaluations to gain understanding of the operative oxidation mechanisms, to obtain oxidation rate data, and to make projections of potential long-term fuel oxidation states. Time and temperature dependence of existing models will be evaluated, and the dependence of the model projections on fuel variables will be determined. 27 refs., 7 figs., 4 tabs.
Research Organization:
Hanford Engineering Development Lab., Richland, WA (United States)
DOE Contract Number:
AC06-76FF02170
OSTI ID:
59371
Report Number(s):
HEDL--7540; ON: DE85013265
Country of Publication:
United States
Language:
English