This is important because scientists believe that groundwater is the most likely way radioactive materials could be released from a repository. Little rainfall at Yucca Mountain Yucca Mountain is in the southern part of the Great Basin, where there is very little rainfall, most of which quickly runs off the surface or evaporates. Scientists think that only an extremely small fraction of that rain could soak into the ground and actually reach the underground area where the potential repository would be located. But they are conducting studies to determine the exact nature of the movement of water through the rock. Models and data have indicated that water infiltration could be diverted laterally away from the repository level, potentially acting as a buffer against increased rainwater infiltration in the event of future climatic changes.
Geologists call the rocks and soil above the water table the unsaturated zone.
These factors significantly limit the change of water reaching the corroding waste containers and carrying radioactive material away from a repository. Earthquakes and faults of particular significance Project scientists have been studying faults and monitoring earthquakes in the region surrounding Yucca Mountain for more than 10 years. Experience with earthquakes throughout the world has shown that, generall, underground structures can withstand ground motion generated by earthquakes. Tests involving nuclear explosions underground at the Nevada Test Site have shown that underground structures can withstand ground motion greater than that anticipated from earthquakes. As part of the studies, there are major trenching programs at Yucca Mountain to study movement of faults during the past two million years.