A STRATEGY FOR VALIDATING A CONCEPTUAL-MODEL FOR RADIONUCLIDE MIGRATION IN THE SATURATED ZONE BENEATH YUCCA MOUNTAIN

A conceptual model for radionuclide migration in the saturated zone be neath Yucca Mountain is presented. The available hydrologic data from the site is compiled to present a qualitative picture of transport of radionuclides horizontally within the first 100-200 meters of the satu rated zone. The transport model consists of flow within fractures and interchange of dissolved species between the fractures and surrounding matrix blocks via molecular diffusion. A parametric study illustrates that at the groundwater conditions expected to exist in the saturated zone, radionuclide will have ample time to diffuse fully within the m atrix blocks. The result is a predicted solute transport time several orders of magnitude greater than the groundwater travel time (GWTT). T o validate this model, a suite of interwell tracer tests are proposed at various flow rates and with conservative and sorbing species. Numer ical simulations show that these tests will allow us to discriminate b etween a matrix diffusion model and a more conventional continuum tran sport model.