Direct characterization of transport parameters in near-field and engineered backfill/invert materials
Conference
Conca, JL, Robinson, BA, Triay, IR et al. (1997). Direct characterization of transport parameters in near-field and engineered backfill/invert materials
. 465
Conca, JL, Robinson, BA, Triay, IR et al. (1997). Direct characterization of transport parameters in near-field and engineered backfill/invert materials
. 465
Performance assessment of a potential repository at Yucca Mountain includes flow and transport modeling of the unsaturated zone as the critical predictive component, and involves a series of model calculations that provide predictions of the migration of important radionuclides in the inventory to the water table. The modeling requires the relevant properties of both the natural environment and the engineered systems. The Unsaturated Flow Apparatus, UFA, was used to directly measure the unsaturated and saturated transport properties of whole rock tuff cores and candidate barrier materials to provide real input parameters to the models. These properties included hydraulic conductivity, matric potential, air permeability, and diffusion coefficient, all of which are strong functions of the volumetric water content. Results show that for all recharges above 0.1 mm/yr, fractures will be partially saturated and conducting at that recharge rate. Whenever the thermal conditions relax enough to allow rewetting of the host rock, there will be dripping from the drift ceiling. Unsaturated transport of colloids through fractured cores of Topopah Spring and Prow Pass tuffs was also investigated and found to depend primarily upon colloid charge, and not size, for the rock cores investigated.
