The impact of repository heat on thermo-hydrological performance at Yucca Mountain
To safely and permanently store high-level nuclear waste, the potential Yucca Mountain repository site must mitigate the release and transport of radionuclides for tens of thousands of years. In the failure scenario of greatest concern, water would contact a waste package (WP), accelerate its failure rate, and eventually transport radionuclides to the water table. These analyses have demonstrated that the only significant source of liquid water is nonequilibrium fracture flow from: (1) meteoric sources, (2) condensate drainage generated under boiling conditions, and (3) condensate drainage generated under sub-boiling conditions. The first source of liquid water arises from the ambient system; the second and third sources are generated by repository heat. Buoyant vapor flow, occurring either on a sub-repository scale or on a mountain scale, may play an important role in the generation of the second and third sources of liquid water. By considering a wide range in bulk permeability, k{sub b}, the authors identify the threshold k{sub b} (called k{sub b}{sup hyd}) at which buoyant, vapor convection begins to dominate hydrological behavior, and the threshold k{sub b} (called k{sub b}{sup th}) at which this convection begins to dominate thermal behavior. They find that k{sub b}{sup th} is generally an order of magnitude larger than k{sub b}{sup hyd} and that the development of a large above-boiling zone suppresses the effects of buoyant vapor flow. Of particular concern are conditions that promote the focusing of vapor flow and condensate drainage, which could result in persistent two-phase conditions (often referred to as the heat-pipe effect) in the vicinity of WPs. The results of this study underscore the need for in situ heater tests to help diagnose the potential for the major repository-heat-driven sources of fracture flow.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 140362
- Report Number(s):
- UCRL-JC-114791; CONF-9309228-7; ON: DE94004349; TRN: 94:002047
- Resource Relation:
- Conference: Focus 93: site characterization and model validation, Las Vegas, NV (United States), 26-29 Sep 1993; Other Information: PBD: Sep 1993
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
54 ENVIRONMENTAL SCIENCES
YUCCA MOUNTAIN
SITE CHARACTERIZATION
TEMPERATURE DEPENDENCE
WASTE FORMS
HYDROLYSIS
RADIOACTIVE WASTE DISPOSAL
METEORIC WATER
THERMAL POLLUTION
WASTE HEAT
RADIONUCLIDE MIGRATION
PERMEABILITY
HYDROLOGY
LIQUID FLOW
GAS FLOW
EVAPORATION
VAPOR CONDENSATION
MATHEMATICAL MODELS
Yucca Mountain Project