Modeling Long-Term Health and Environmental Risk at the Nevada Test Site GoldSim modelers at Neptune and Company have developed a contaminant transport and regulatory compliance model of a radioactive waste disposal site at the Nevada Test Site (NTS), northwest of Las Vegas, Nevada. The model is a management system tool that supports health and evironmental risk assessment and effective long-term management of the NTS low-level radioactive waste disposal facilities. In addition to the classical waterborne transport of radionuclides, Neptune's model includes transport of subsurface materials to the ground surface by burrowing animals and the transport of contamination to the surface by plants. The modeled subsurface consists of a vertically oriented cylinder of waste and alluvial overburden nested inside another cylinder of surrounding alluvium. Both the interior cylinder and the annular ring are subdivided into several cells, in order to model contaminant transport by advection of water, diffusion in the water phase, advection of alluvium by burrowing animals, and plant-induced transport. For more information, check out the full article in the Fall 2001 newsletter.