HR: 0830h
AN: H21D-0835    [PDF]
TI: Reactive Transport Model for Fracture and Matrix Geochemistry at Yucca Mountain, Nevada
AU: * Browning, L
EM: lbrowning@cnwra.swri.edu
AF: Center for Nuclear Waste Regulatory Analyses, Southwest Research Institute, 6220 Culebra Rd., San Antonio, TX 78238 United States
AU: Murphy, W M
AF: Department of Geological and Environmental Sciences, California State University, California State University 400 W. First St., Chico, CA 95929-0205 United States
AU: Manepallyl, C
AF: Center for Nuclear Waste Regulatory Analyses, Southwest Research Institute, 6220 Culebra Rd., San Antonio, TX 78238 United States
AU: Fedors, R
AF: Center for Nuclear Waste Regulatory Analyses, Southwest Research Institute, 6220 Culebra Rd., San Antonio, TX 78238 United States
AB: Reactive transport models for the potential nuclear waste repository at Yucca Mountain (YM) provide information on evolving water chemistries and secondary mineralogies, which may affect engineered barrier system performance, radionuclide releases, and radionuclide transport. Although reactive transport models permit explicit analysis of coupled thermal-hydrological-chemical processes important to predictions of long-term repository performance, these predictions have sources of uncertainty that are difficult to quantify. Confidence in reactive transport models of YM therefore requires demonstration of their capability to represent natural conditions. Site characterization studies at YM have revealed significant differences between the hydrogeochemical properties of fracture and matrix materials in the unsaturated zone (UZ) overlying the potential waste emplacement setting. A quantitative evaluation of the most significant hydrogeochemical processes that caused these differences is required to develop detailed estimates of the quantity and chemistry of water contacting engineered materials in a thermally-perturbed repository setting-one of the most risk-significant components of performance assessment for YM. Developing a reliable explanation for observed differences between UZ matrix and fracture materials at YM thus provides a critical test for the reactive transport models that support performance assessments for a potential repository at YM. We developed a 1D, dual continuum, reactive transport model of the ambient UZ matrix/fracture system at YM in order to evaluate the origin and evolution of groundwater compositions and secondary minerals in fracture and matrix materials overlying the location of the potential repository. Sensitivity tests were conducted to gauge the importance of data and model uncertainties. This paper is an independent product of the CNWRA and does not necessarily reflect the view or regulatory position of the U.S. Nuclear Regulatory Commission.
DE: 1806 Chemistry of fresh water
DE: 1829 Groundwater hydrology
DE: 1832 Groundwater transport
DE: 1875 Unsaturated zone
SC: Hydrology [H]
MN: 2003 Fall Meeting