Encyclopedia > Yucca Mountain
Yucca Mountain
Like all nuclear facilities this one is also highly controversial.
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Backgroud Spent nuclear fuel is the radioactive by-product of making electricity at commercial nuclear power plants and high-level radioactive waste is the by-product from production at defense facilities. In 1982, the US Congress established a national policy to solve the problem of nuclear waste disposal. This policy is a federal law called the Nuclear Waste Policy Act[?]. Congress based this policy on what most scientists worldwide agreed is the best way to dispose of nuclear waste.
The Nuclear Waste Policy Act made the U.S. Department of Energy responsible for finding a site, building, and operating an underground disposal facility called a geologic repository. The recommendation to use a geologic repository dates back to 1957 when the National Academy of Sciences recommended that the best means of protecting the environment and public health and safety would be to dispose of the waste in rock deep underground.
In 1983, the DOE selected nine locations in six states for consideration as potential repository sites. This was based on data collected for nearly 10 years. The nine sites were studied and results of these preliminary studies were reported in 1985. Based on these reports, the president approved three sites for intensive scientific study called site characterization. The three sites were Hanford, Washington; Deaf Smith County, Texas; and Yucca Mountain, Nevada.
In 1987, Congress amended the Nuclear Waste Policy Act and directed DOE to study only Yucca Mountain which is already located within a former nuclear test site. The Act stressed that if, at any time, Yucca Mountain is found unsuitable, studies will be stopped immediately. If that happens, the site will be restored and DOE will seek new direction from Congress.
The purpose of the Yucca Mountain project is to determine if Yucca Mountain is a suitable site for a spent nuclear fuel and high-level radioactive waste repository. Science Application International Corporation is the current contractor for the site and 1800 people work on the project. The main tunnel of the Exploratory Studies Facility is U-shaped 5 miles long and 25 feet wide. There are also several cathedral-like alcoves that branch from the main tunnel. It is in these alcoves that most of the scientific experiments are conducted.
The proposed repository zone will cover 1150 acres, be 1000 feet below the surface of the mountain and 1000 feet above the water table when/if it is completed. By early 2002, 7 billion US dollars had been spent on the project which has made Yucca Mountain the most studied piece of geology in the world.
The tunnel boring machine[?] (TBM) that excavated the main tunnel cost 13 million US dollars and was 400 feet in length when it was in operation. It now sits at its exit point at the South Portal (south entrance) of the facility. The short side tunnel alcoves were excavated using explosives.
Controversy 2010 is the projected date that the facility will begin to accept waste. This project is widely opposed in Nevada and is a hotly debated topic. The state of Nevada is with-holding the renewal of water rights[?] to the facility which has forced the contractor to truck-in water. Polls indicate that most Nevadans feel that since the US federal government lied about the safety of the nuclear bomb tests, they cannot be trusted in their current assertions the the Yucca Mountian site will be safe. There is also general resentment felt by many Nevada residents over the fact that 87% of the land in Nevada is federal property. The nuclear waste is also planned to be shipped to the site by rail which raises concerns for many people over the possibility of rail accidents, sabotage or even theft by terrorists. Officials counter by pointing to extensive testing of waste containers that show their extreme robustness in the worst situations.
On February 12, 2002 the US Secretary of Energy made the decision that this site was suitable to be the nation's nuclear repository. Nevada's governor had 90 days to object and he did so but the United States Congress overode the objection. If the objection did stand then the site would have to be cleaned-up, closed and a new site chosen.
Geology Yucca Mountain is located within Nye County in south central Nevada. The formation that makes up Yucca Mountain was created by several large eruptions from a caldera volcano and is composed of alternating layers of welded-tuff, non-welded tuff end semi-welded tuff. Tuff has special physical, chemical and thermal characteristics that make it suitable as a choice material to entomb radioactive waste for the projected 10,000 years required for the waste to become safe through radioactive decay.
Like any geologic formation, Yucca Mountain is criss-crossed by cracks and fissures. Some of these cracks extend from the planned storage area all the way to the water table 1000 feet below. It is feared by some that these cracks may provide an express route for radioactive waste after the predicted containment failure of the waste containers several hundred years from now. Officials state that the waste containers will be stored in such a way to minimized or even nearly eliminate this possibility. Even without cracks tuff is slightly permeable to water but due to the depth to the water table it is estimated that by the time the waste enters the water supply it will be safe.
However, the area around Yucca Mountain received much more rain in the geologic past and the water table was consequentely much higher than it is today. Critics contend that future climate cannot be predicted to 10,000 years so it is optimistic to assume that the area will similarly arid as it is today. Most geologists that have worked at the site still maintain that the geology will adequately slow the rate of waste seepage to protect water supplies even if the local climate becomes much wetter.
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