Earth Sciences Division (ESD) Department of Energy (DOE) Lawrence Berkeley National Laboratory (LBNL)

The Yucca Mountain Project: Numerical Modeling:
Thermal-Coupled Process Models

Modeled Gas Phase CO2 Concentrations (log ppmv)  in Fractures, and Matrix Temperatures (contour lines)  during the Cooling Phase of the Drift-Scale Test at 5 Years Thermal-coupled process models used for the Yucca Mountain Project were developed and used to investigate the coupling of thermal and hydrological processes. More comprehensive coupled process models were also developed and used for thermal-hydrological-chemical coupled processes and thermal-hydrological-mechanical coupled processes. All coupled process effects were investigated at the drift scale and mountain scale. Drift-scale models were used to investigate the effects of coupled processes on drift seepage rates and seepage water composition. Mountain-scale models were used to investigate the impact of coupled processes on large-scale flow patterns affecting percolation flux at and beneath the repository and effects on pore water and mineral composition. Thermal-coupled process models were based on the same geological and conceptual model framework used for the unsaturated zone flow model. Therefore, properties developed for the unsaturated zone flow model were also used for the thermal-coupled process models. Model validation for thermal-coupled process models used data from the single-heater test and drift-scale test.

Fracture Saturation and Liquid Flux for Tptpmn Submodel  with Heterogeneous Permeability Field at 1,000 Years. Certain aspects of drift-scale thermal-hydrological and thermal-hydrological-chemical coupled processes were found to have a significant impact on drift seepage and seepage water composition. Therefore, these aspects of the coupled process models were incorporated into abstraction models for seepage rate and seepage water composition used in total system performance assessment. Other aspects of coupled processes, such as thermal-hydrological-mechanical effects and mountain-scale thermal-hydrological and thermal-hydrological-chemical effects were found to have only minor effects on system behavior important for performance assessment. Therefore, these aspects of the coupled process models were used to support exclusion from performance assessment.

References

  • Wu, Y-S.; Mukhopadhyay, S.; Zhang, K.; and Bodvarsson, G.S. 2006. “A Mountain-Scale Thermal–Hydrologic Model for Simulating Fluid Flow and Heat Transfer in Unsaturated Fractured Rock.” Journal of Contaminant Hydrology, 86, 128-159. New York, New York: Elsevier. TIC: 259285.
  • Spycher, N.F.; Sonnenthal, E.L.; and Apps, J.A. 2003. “Fluid Flow and Reactive Transport Around Potential Nuclear Waste Emplacement Tunnels at Yucca Mountain, Nevada.” Journal of Contaminant Hydrology, 62-63, 653-673. New York, New York: Elsevier. TIC: 254205.
  • Birkholzer, J.T.; Mukhopadhyay, S.; and Tsang, Y.W. 2004. “Modeling Seepage into Heated Waste Emplacement Tunnels in Unsaturated Fractured Rock.” Vadose Zone Journal, 3, 819-836. Madison, Wisconsin: Soil Science Society of America. TIC: 256702.
  • Rutqvist, J. and Tsang, C-F. 2003. "Analysis of Thermal-Hydrologic-Mechanical Behavior Near an Emplacement Drift at Yucca Mountain." Journal of Contaminant Hydrology, 62-63, 637-652. New York, New York: Elsevier. TIC: 254205.
For more information, please contact:

Jim Houseworth
Yucca Mountain Project Lead
Earth Sciences Division
Phone: 702-295-4833
Fax: 702-295-7742
Email: JEHouseworth@lbl.gov