CHM333:

Impact of Yucca Mountain on its Surrounding Environment

The U.S. Department of Energy (DOE) has compiled an Environmental Impact Statement (EIS) for the Yucca Mountain Project. This section of the web site will seek to summarize the findings of the DOE in relation to possible radioactive contamination of the environment surrounding the project.

The physical site of the proposed Yucca Mountain repository. Source

Impact on Air Quality

It has been determined that the primary radionuclide to be released from Yucca Mountain would be Radon-222 (and its radioactive decay products), which is naturally occurring. There would also be trace emissions of Krypton-85 during the operations period when wastes would be moved from their transportation casks. The DOE determined that the maximum possible radiation exposure to any member of the public would range from 0.73 millirem per year to 1.3 millirem per year and that 99.99% of this would be from Radon-222 and the products of its decay. A typical person is exposed to about 200 millirem per year as a result of radon. This increase is thus minimal.6

Impacts on Groundwater

Of all the aspects of the environment that can be contaminated, the most likely area of contamination is the groundwater running below the mountain. Although Yucca Mountain is located in a desert with little precipitation, and is also at least 200 meters below the surface and at least 160 meters above the water table, there is a slight possibility that water surface water from precipitation may be able to travel through the surface of the mountain, into the nuclear waste storage area where it will cause the waste packages to corrode and leak. The water can then mix with the leaking radioactive material and travel farther down into the mountain until it reaches the water table and contaminates the ground water.

A representation of the possible groundwater contamination threat that the Yicca Mountain repository poses. Source

The possibility of this actually occurring is very remote. It rarely rains in the Yucca Mountain vicinity, and when it does, most of the water runs off. Very little water infiltrates the rock surface. A fraction of the water that does infiltrate the rock surface of the mountain is evaporated. The remaining water that does flow through the unsaturated zone must flow through the waste storage area and come in contact with leaking waste. Also, the water may come in contact with a waste package and cause it to leak. Now the contaminated water, or leaking radioactive waste must travel down another 160 meters of thick rock. This will take a long time and is not very likely.

There are, however, several factors that increase the likelihood of this occurring. One is the presence of two faults on near the site. One fault is the Ghost Dance fault, which occurs within the repository block. Another fault is the Solitario Canyon Fault, which forms the western boundary of the repository block. These faults make it easier for water to travel through the system, and more likely that water gets into the system. Other possible factors that increase the likelihood of this scenario occurring are possible weather changes over time (in this case more annual precipitation), possible geologic changes in the mountain that allow water to leak into the system, and the gradual decay due to old age of the waste packages.7