Multiscale Thermohydrologic Model Analyses of Heterogeneity and Thermal-Loading Factors for the Proposed Repository at Yucca Mountain
The MultiScale ThermoHydrologic Model (MSTHM) predicts thermohydrologic (TH) conditions in emplacement drifts and the adjoining host rock throughout the proposed nuclear-waste repository at Yucca Mountain. The MSTHM is a computationally efficient approach that accounts for TH processes occurring at a scale of a few tens of centimeters around individual waste packages and emplacement drifts, and for heat flow at the multi-kilometer scale at Yucca Mountain. We present recent MSTHM simulations that address the influence of repository-scale thermal-conductivity heterogeneity and the influence of preclosure operational factors affecting thermal-loading conditions. We can now accommodate a complex repository layout with emplacement drifts lying in non-parallel planes using a superposition process that combines results from multiple mountain-scale submodels. This development, along with other improvements to the MSTHM, enables more rigorous analyses of preclosure operational factors. These improvements include the ability to (1) predict TH conditions on a drift-by-drift basis, (2) represent sequential emplacement of waste packages along the drifts, and (3) incorporate distance- and time-dependent beat-removal efficiency associated with drift ventilation. Alternative approaches to addressing repository-scale thermal-conductivity heterogeneity are investigated. We find that only one of the four MSTHM submodel types needs to incorporate thermal-conductivity heterogeneity. For a particular repository design, we find that the most influential parameters are (1) percolation-flux distribution, (2) thermal-conductivity heterogeneity within the host-rock units, (3) the sequencing of waste-package emplacement, and (4) the duration of the preclosure ventilation period.
- Research Organization:
- Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
- Sponsoring Organization:
- US Department of Energy (US)
- DOE Contract Number:
- W-7405-ENG-48
- OSTI ID:
- 15002260
- Report Number(s):
- UCRL-JC-150011; TRN: US0400720
- Resource Relation:
- Conference: 2003 International High-Level Radioactive Waste Management Conference, Las Vegas, NV (US), 03/30/2003--04/02/2003; Other Information: PBD: 4 Nov 2002
- Country of Publication:
- United States
- Language:
- English
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Multiscale Thermohydrologic Model Analyses of Heterogeneity and Thermal-Loading Factors for a Proposed Nuclear Waste Repository
Multiscale Thermohydrologic Model Analyses of Heterogeneity and Thermal-Loading Factors for a Proposed Nuclear Waste Repository