Evaluating the Moisture Conditions in the Fractured Rock at YuccaMountain: The Impact of Natural Convection Processes in HeatedEmplacement Drifts
The energy output of the high-level radioactive waste to beemplaced in the proposed geologic repository at Yucca Mountain, Nevada,will strongly affect the thermal-hydrological (TH) conditions in thenear-drift fractured rock. Heating of rock water to above-boilingconditions will induce large water saturation changes and fluxperturbations close to the waste emplacement tunnels (drifts) that willlast several thousand years. Understanding these perturbations isimportant for the performance of the repository, because they couldincrease, for example, the amount of formation water seeping into theopen drifts and contacting waste packages. Recent computational fluiddynamics (CFD) analysis has demonstrated that the drifts will act asimportant conduits for gas flows driven by natural convection. As aresult, vapor generated from boiling of formation water nearelevated-temperature sections of the drifts may effectively betransported to cooler end sections (where no waste is emplaced), wouldcondense there, and subsequently drain into underlying rock units. Thus,natural convection processes have great potential for reducing thenear-drift moisture content in heated drift sections, which has positiveramifications for repository performance. To study these processes, wehave developed a new simulation method that couples existing tools forsimulating TH conditions in the fractured formation with modules thatapproximate natural convection and evaporation conditions in heatedemplacement drifts. The new method is applied to evaluate the future THconditions at Yucca Mountain in a three-dimensional model domaincomprising a representative emplacement drift and the surroundingfractured rock.
- Research Organization:
- Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
- Sponsoring Organization:
- USDOE Office of Civilian Radioactive WasteManagement
- DOE Contract Number:
- DE-AC02-05CH11231
- OSTI ID:
- 901670
- Report Number(s):
- LBNL-59334; R&D Project: G71774; BnR: YN1901000; TRN: US0702654
- Journal Information:
- Vadose Zone Journal, Vol. 5; Related Information: Journal Publication Date: 2006
- Country of Publication:
- United States
- Language:
- English
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