More than 800 underground nuclear tests were conducted on the Nevada National Security Site (NNSS) (formerly the Nevada Test Site), including 61 "tunnel tests" in fractured rock of Rainier Mesa. In collaboration with Lawrence Livermore and Los Alamos National Labs, DRI is developing models to predict radionuclide transport from underground nuclear tests within the unsaturated zone of Rainier Mesa over the next 1,000 years. Because of the complexity of fractured rock environments, the modeling must account for variably saturated flow in factures and faults, as well as the rock matrix. Other uncertainties are the extent of perched aquifers, recharge, the potential for lateral flow, and to what extent matrix diffusion could retain radionuclides. The Rainier Mesa modeling is one component of DRI's research on the subsurface characterization, radionuclide transport and management of contaminated groundwater for the Underground Testing Area Project for the NNSS.

	Model of groundwater flow in fractures for Rainier Mesa on the Nevada National Security Site for input in a groundwater flow and contaminant model.
	Percent saturation of fracture in rocks on Rainier Mesa on the Nevada National Security Site at a recharge rate of 20 mm per year.