Effects of annular air gaps surrounding an emplaced nuclear waste canister in deep geologic storage
Annular air spaces surrounding an emplaced nuclear waste canister in deep geologic storage will have significant effects on the long-term performance of the waste form. Addressed specifically in this analysis is the influence of a gap on the thermal response of the waste package. Three dimensional numerical modeling predicts temperature effects for a series of parameter variations, including the influence of gap size, surface emissivities, initial thermal power generation of the canister, and the presence/absence of a sleeve. Particular emphasis is placed on determining the effects these variables have on the canister surface temperature. We have identified critical gap sizes at which the peak transient temperature occurs when gap widths are varied for a range of power levels. It is also shown that high emissivities for the heat exchanging surfaces are desirable, while that of the canister surface has the greatest influence. Gap effects are more pronounced, and therefore more effort should be devoted to optimal design, in situations where the absolute temperature of the near field medium is high. This occurs for higher power level emplacements and in geomedia with low thermal conductivities. Finally, loosely inserting a sleeve in the borehole effectively creates two gaps and drastically raises the canister peak temperature. It is possible to use these results in the design of an optimum package configuration which will maintain the canister at acceptable temperature levels. A discussion is provided which relates these findings to NRC regulatory considerations.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Northern Arizona Univ., Flagstaff (USA)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 5277790
- Report Number(s):
- UCRL-84152; TRN: 80-011213
- Country of Publication:
- United States
- Language:
- English
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CONTAINERS
ANNULAR SPACE
TEMPERATURE EFFECTS
UNDERGROUND DISPOSAL
RADIOACTIVE WASTE DISPOSAL
BASALT
EMISSIVITY
EXPERIMENTAL DATA
HEAT TRANSFER
MATHEMATICAL MODELS
PERFORMANCE
SALT DEPOSITS
SLEEVES
SURFACES
THERMAL CONDUCTIVITY
CONFIGURATION
DATA
ENERGY TRANSFER
GEOLOGIC DEPOSITS
INFORMATION
MANAGEMENT
NUMERICAL DATA
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
SURFACE PROPERTIES
THERMODYNAMIC PROPERTIES
WASTE DISPOSAL
WASTE MANAGEMENT
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