The Nevada Test Site: An analog for a nuclear repository

The United States proposes to store high level nuclear wastes underground; a site at Yucca Mountain in southern Nevada is currently under evaluation. A major concern is that radioactive materials may dissolve in the groundwater and be transported to the accessible environment. At the Nevada Test Site (NTS) adjacent to Yucca Mountain underground nuclear tests have been conducted for over 30 years. Radionuclides (unreacted fissile material, activation products, fission products) from these tests remain underground with no confinement by engineered barriers. The US Department of Energy has supported studies since 1973 designed to measure the distribution of these radionuclides and to evaluate the processes by which they might be transported by groundwater. The authors describe here some of what they have learned about how radionuclides are distributed around nuclear test cavities and how they interact with groundwater