Assessment of nitrogen as an atmosphere for dry storage of spent LWR fuel
Interim dry storage of spent light-water reactor (LWR) fuel is being developed as a licensed technology in the United States. Because it is anticipated that license agreements will specify dry storage atmospheres, the behavior of spent LWR fuel in a nitrogen atmosphere during dry storage was investigated. In particular, the thermodynamics of reaction of nitrogen compounds (expected to form in the cover gas during dry storage) and residual impurities (such as moisture and oxygen) with Zircaloy cladding and with spent fuel at sites of cladding breaches were examined. The kinetics of reaction were not considered it was assumed that the 20 to 40 years of interim dry storage would be sufficient for reactions to proceed to completion. The primary thermodynamics reactants were found to be NO/sub 2/, N/sub 2/O, H/sub 2/O/sub 2/, and O/sub 2/. The evaluation revealed that the limited inventories of these reactants produced by the source terms in hermetically sealed dry storage systems would be too low to cause significant spent fuel degradation. Furthermore, the oxidation of spent fuel to degrading O/U ratios is unlikely because the oxidation potential in moist nitrogen limits O/U ratios to values less than UO/sub 2.006/ (the equilibrium stoichiometric form in equilibrium with moist nitrogen). Tests were performed with bare spent UO/sub 2/ fuel and nonirradiated UO/sub 2/ pellets (with no Zircaloy cladding) in a nitrogen atmosphere containing moisture concentrations greater than encountered under dry storage conditions. These tests were performed for at least 1100 h at temperatures as high as 380/sup 0/C, where oxidation reactions proceed in a matter of minutes. No visible degradation was detected, and weight changes were negligible.
- Research Organization:
- Pacific Northwest Labs., Richland, WA (USA)
- DOE Contract Number:
- AC06-76RL01830
- OSTI ID:
- 5188924
- Report Number(s):
- PNL-5569; ON: DE86001944
- Country of Publication:
- United States
- Language:
- English
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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201 -- Chemical & Physicochemical Properties
ACTINIDE COMPOUNDS
ATMOSPHERES
BWR TYPE REACTORS
CHALCOGENIDES
CHEMICAL REACTIONS
CONTROLLED ATMOSPHERES
DATA
DRY STORAGE
ELEMENTS
ENERGY SOURCES
EXPERIMENTAL DATA
FUELS
HYDROGEN COMPOUNDS
HYDROGEN PEROXIDE
INFORMATION
MATERIALS
NITRIC OXIDE
NITROGEN
NITROGEN COMPOUNDS
NITROGEN OXIDES
NITROUS OXIDE
NONMETALS
NUCLEAR FUELS
NUMERICAL DATA
OXIDATION
OXIDES
OXYGEN
OXYGEN COMPOUNDS
PEROXIDES
PWR TYPE REACTORS
REACTOR MATERIALS
REACTORS
SPENT FUEL STORAGE
SPENT FUELS
STORAGE
THERMODYNAMICS
URANIUM COMPOUNDS
URANIUM DIOXIDE
URANIUM OXIDES
WATER COOLED REACTORS
WATER MODERATED REACTORS