Two-phase flow experiments in natural rock fractures from Yucca Mountain

摘要

The welded tuffs in the vadose zone of Yucca Mountain, Nevada, are being investigated as the potential site of a geologic repository for high-level nuclear wastes. The welded tuffs have very low permeability, offering protection from flowing groundwater. The repository horizon, although of low permeability, is known to be fractured, suggesting the possibility of fast paths for contaminant transport. As part of the repository evaluation, this study has been undertaken to characterize fractures from Yucca Mountain tuffs. Another purpose of this study is to gain insight into pore-level phenomena occurring during multiphase flow in fractures generally. For this reason measurements were made not only in the actual fractures, but also in transparent replicas that reproduce the fracture void geometry. Use of transparent replicas allows observation of displacement phenomena and estimation of fracture saturation.