Flow and transport of radionuclides in unsaturated fractured basalt

A modeling analysis of radionuclide transport in the vadose zone is described. The central focus of the modeling is to develop an understanding of the nature of flow and transport at the site of concern. Characterization of the site is still incomplete, including the presence of perched water, and observed contaminant migration. The problem of modeling fluid flow and transport processes is made difficult by the alternate layers of sedimentary materials and fractured basalts that characterize the geologic setting. The modeling results give qualitative agreement with monitoring data from the site --- suggesting that fracture flow is an important component of the flow system. 7 refs., 9 figs.