Yucca Mountain repository

 

 U.S. Dept. of EnergyLocation of Yucca Mountain, Nevada. Credit: U.S. Dept. of EnergyYucca Mountain Repository is the proposed United States Department of Energy (DOE) deep geological repository storage facility for spent nuclear reactor fuel and other radioactive waste. Yucca Mountain is located in a remote desert on federal land within the  boundaries of the Nevada Test Site in Nye County, Nevada. It is approximately 100 miles northwest of Las Vegas, Nevada. DOE began studying Yucca Mountain, Nevada, in 1978 to determine whether it would be suitable for the nation's first long-term geologic repository for spent nuclear fuel and high-level radioactive waste. Currently stored at 121 sites around the nation, these materials are a result of nuclear power generation and national defense programs.

The proposal to store radioactive waste in Yucca Mountain is controversial. Opponents argue that climate change, erosion, earthquakes, and other natural forces could make the site unsuitable for long term storage. DOE's Office of Civilian Radioactive Waste maintains that extensive scientific and engineering analysis of the site indicates that it is safe and secure.DOE was to begin accepting spent fuel at the Yucca Mountain Repository by January 31, 1998 but has yet to do so because of a series of delays due to legal challenges, concerns over how to transport nuclear waste to the facility, and political pressures from those opposed to the siting.

In June 2008, the DoE submitted an 8,600 page license application to the Nuclear Regulatory Commission (NRC) for the construction of the repository. The NRC  has a statute time limit of 3 to 4 years to complete its safety analysis and public hearings. The current (December, 2008) projected completion date for the project is 2017, but President-elect Obama has indicated that he may be opposed to storing waste at Yucca Mountain. 

Background

 SRNLSpent nuclear fuel rods at the Department of Energy's Savannah River National Laboratory in Aiken, South Carolina. Credit: SRNLSpent nuclear fuel is the radioactive by-product of electric power generation at commercial nuclear power plants, and high-level radioactive waste is the by-product from reprocessing spent fuel to produce fissile material for nuclear weapons. In 1982, the United States 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, which made the DOE responsible for finding a site, building, and operating an underground disposal facility called a geologic repository. 

In 1984 the DOE selected ten locations in six states for consideration as potential repository sites. The ten sites were studied and results of these preliminary studies were reported in 1985. Based on these reports, President Reagan approved three sites for intensive scientific study called site characterization: Hanford, Washington; Deaf Smith County, Texas; and Yucca Mountain. 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 provided that if, at any time, Yucca Mountain is found unsuitable, studies will be stopped immediately. If that should happen, the site will be restored and DOE will seek new directions from Congress.

On July 23, 2002, President George W. Bush signed House Joint Resolution 87, allowing the DOE to take the next step in establishing a safe repository in which to store the country's nuclear waste. On July 18, 2006 the DOE proposed March 31, 2017 as the date to open the facility and begin accepting waste based on full funding. On September 8, 2006 Ward (Edward) Sproat, a nuclear industry executive formerly of PECO energy in Pennsylvania, was nominated by President Bush to lead the Yucca Mountain Project. Following the 2006 mid-term Congressional elections, Nevada Senator Harry Reid, a long time opponent of the repository, became the Senate Majority Leader, putting him in a position to greatly affect the future of the project. Reid has said that he would continue to work to block completion of the project, and is quoted as having said: "Yucca Mountain is dead. It'll never happen."

In 2007, the DOE announced it was seeking to double the size of the Yucca Mountain repository to a capacity of 135,000 metric tons, or 300 million pounds. The capacity expansion was needed to handle the additional waste from the expansion of generation at existing nuclear power plants.

In the 2008 Omnibus Spending Bill, the Yucca Mountain Project's budget was reduced to $390 million. Despite this cut in funding, the project was able to reallocate resources and delay transportation expenditures to complete the License Application for submission on June 3, 2008. Lacking an operating repository, however, the federal government owes to the utilities somewhere between $300 and $500 million per year in compensation for failing to comply with the contract it signed to take the spent nuclear fuel by 1998.

The Facility

 U.S. Dept. of EnergyCutaway image of Yucca Mountain, its rock layers, and the planned network of repository tunnels. Source: U.S. Dept. of EnergyThe basic idea of geologic disposal is to place carefully packaged radioactive materials in tunnels deep underground. A series of barriers prevent or slow the movement of radioactive materials from a repository. These barriers include natural ones, such as thick unsaturated rock, and human-engineered barriers. These barriers are designed to reduce the total amount of any radioactivity that could eventually reach the water table where people might pump it from the ground and use it.

The current design for the potential repository calls for spent nuclear fuel and high-level radioactive waste to travel to Yucca Mountain by truck or rail in specially designed, shielded shipping containers.

Once these materials arrive at the repository, they would be removed from the shipping containers and placed in double-layered, corrosion-resistant packages for burying underground. Special rail cars would carry them underground, and remotely controlled equipment would place them on supports in an underground tunnel.

Waste Canisters

 U.S.Dept of EnergyA Transportation, Aging and Disposal (TAD) canister. Source: U.S.Dept of EnergyPrior to leaving a nuclear power plant, spent fuel rods will be placed in a canister called a Transportation, Aging and Disposal (TAD) canister. Under normal conditions, the rods will permanently remain in the TAD canister. The TAD will be placed in another outer container, depending on where in the process the waste is: transportation, aging or disposal.

  • Prior to leaving a facility for Yucca Mountain, the TAD would be placed in a transportation cask, which is radiation-shielded, sturdy, and impact-resistant. The packages would be shipped primarily by train.
  • At the Yucca Mountain site, the TADs would be removed from the transportation cask and placed in aging or emplacement packages. The TAD canister transfer takes place inside surface facilities using remote-controlled equipment.
  • TAD canisters that need to cool off, or age, before going into the repository will be placed in aging canisters and stored on aging pads located near the waste handling facilities.
  • TAD canisters ready to go directly into the repository will be placed in an additional, corrosion-resistant disposal package.

The Yucca Mountain Repository is designed to hold 70,000 metric tons of spent nuclear fuel and high-level radioactive waste in metal containers. The current design calls for a "canister within a canister" approach consisting of three containers - nested inside one another - to safely dispose of radioactive waste. First, the TAD canister that holds the waste will sit inside a stainless steel canister designed and built to provide additional strength to the package. The package is then placed in the outermost canister consisting of nickel alloy (Alloy 22), which is highly resistant to corrosion.

The Yucca Mountain waste canisters are designed to:

  • Isolate radioactive particles from the outside environment
  • Prevent physical and chemical reactions within the canister
  • Manage the heat of the radioactive content
  • Remain intact during movement, including loading, transportation and emplacement.
 Surface facilities
 U.S. Dept. of Energy3D model view looking approximately south at the planned Yucca Mountain surface facilities. Source: U.S. Dept. of EnergyThe current plan for surface nuclear waste handling facilities at the Yucca Mountain site calls for three waste handling facilities:
  • Receipt Facility – At the receipt facility, waste canisters are removed from the transportation casks and prepared for transfer to the appropriate waste handling facility. This facility also prepares unloaded transportation casks and railcars for return to the National Transportation System for continued use.
  • Initial Handling Facility – As the first building scheduled for completion, the IHF would prepare high-level radioactive waste from government facilities and spent nuclear fuel from the U.S. Navy for disposal.
  • Canister Receipt and Closure Facilities – The Canister Receipt and Closure Facility would receive all disposable canisters, except for naval spent nuclear fuel canisters, and prepare them for disposal. The facilities would be built in phases.
  • Wet Handling Facility – A small percentage of spent nuclear fuel will not arrive at the repository in TADs, but will be shipped in transportation casks designed to handle individual assemblies of spent fuel rods. The Wet Handling Facility includes a pool of water in which spent fuel rods are removed from transportation casks, placed into TAD canisters and prepared for disposal or aging.
Receving and preparing waste

When the waste arrives at the repository, workers will use remote controlled equipment to remove it from transportation casks and place it in special metal containers called waste packages.  The remote controls allow workers to operate equipment from a distance, protecting them from radiation exposure.  Other remote equipment will install and weld inner and outer lids on the waste packages. Cameras and remote sensing equipment would assure that each waste package meets rigorous safety and quality criteria before going underground. Once the waste package welding and inspection is complete, an electric transporter called a Transport and Emplacement Vehicle (TEV) will move into the waste handling facility to transport the waste package to the emplacement tunnels. The TEV travels from the surface facility, enters the main tunnel and moves each loaded waste package to an emplacement tunnel. Once the access doors are opened, the TEV moves in and places the waste package in its designated position

Emplacement tunnels

 U.S. Dept. of EnergyCutaway image showing an emplacement tunnel, waste packages, and drip shield. Source: U.S. Dept. of EnergyEmplacement tunnels, also referred to as “drifts,” are the specially constructed horizontal openings where the waste will be placed for disposal. The current design includes approximately 108 emplacement tunnels. These tunnels would be excavated in solid rock about 1,000 feet beneath the surface of the mountain and, on average, about 1,000 feet above the water table. The tunnels would be 18 feet in diameter, various lengths, and about 250 feet apart. They would be lined with perforated steel plates held in place by rock bolts to prevent rock from falling on the engineered features.

The underground location and the orientation of the emplacement tunnels are based on the following factors:

  • thickness of the overlying rock and soil
  • characteristics of the rock itself (such as porosity)
  • location of the fractures in the rock
  • distance from possible earthquake faults
  • depth to the water table
  • distance from other underground features

The design of the underground layout of the emplacement tunnels is also intended to manage the heat that would be generated by the waste. This heat will influence moisture in the rock, humidity in the tunnels, and other conditions within the repository. In addition, the tunnels are designed so that any water that enters them will drain, by gravity, downward and away from the repository.

The DOE studies suggest that the location and geology of Yucca Mountain would allow small amounts of water to filter through the mountain.  The current system  has feattures to combat any seepage that could reach the radioactive waste container. Thick, stainless steel waste packages with an outer nickel alloy shell and a drip shield designed to protect the packages from exposure to water work together to isolate the radioactive waste.

Repository Closure and Monitoring

Federal regulations require the Department of Energy to monitor the repository after closure. Post-closure activities would include controlling the land and its boundaries, monitoring and testing the surrounding environment, and implementing safeguard and security measures for future generations.

In addition, DOE is required to restore the environment at the site to as close to its original state as possible, including: removing all materials and equipment that are not part of the permanent repository; sealing all openings to the underground facilities, and removing all surface facilities.  A monitoring program would focus on providing increased understanding of the processes, such as seepage and corrosion, which are most important to repository safety.

Preventing human intrusion

 U.S. Dept. of EnergyAn artist's rendering of what one of the permanent markers at Yucca Mountain might look like. Source: U.S. Dept. of EnergyDue to the long-lived radionuclides in the repository, DOE will use different measures to discourage humans from trying to access the repository, and to prevent water from entering through such openings. A network of permanent monuments and markers will be erected around the site to warn future generations of the presence and nature of the buried waste. Detailed public records will identify the location and layout of the repository and information about the waste it contains. The NRC requires that the monuments or markers “accurately identify the location of the repository, be designed to be as permanent as practicable and convey a warning against intrusion into the underground repository, because of risk to public health and safety from radioactive wastes.”

The current plan envisions a series of tall, enduring monuments about 25 feet high would be placed along the site’s perimeter as well as on and near the mountain’s crest. They would be designed to be noticed and to endure natural events, even water from future floods or the build-up of sand dunes deposited by wind. The warning messages on the monuments would be inscribed in several languages as well as pictures and symbols. The languages that would be used are the six official languages of the United Nations: Arabic, Chinese, English, French, Russian, and Spanish. The messages may also be displayed in some simplified form of the sign language used by the hearing impaired. Linguists have recommended that a variety of picture symbols be used, including perhaps a unique international symbol for “nuclear waste repository.”

These messages would be inscribed about 40 inches or higher above the ground’s surface to prolong legibility. To better withstand corrosion and erosion, the monuments could be constructed from either granite or basalt. The messages must survive natural forces and remain legible and comprehensible as long as possible. Natural factors to be considered are abrasion from wind-borne particles, general surface erosion, and “desert varnish,” a dark coating or polish often found on rock surfaces after long exposure in desert regions; desert varnish is typically caused by a buildup of iron and manganese oxides.

The shapes and dimensions of the monuments are also important factors. The current concept calls for the perimeter monuments to be six-sided cones pointing upwards at varying angles. As shown in the schematic drawing, they would rise out of the ground above the repository near the larger monuments, as well as around the entire surface perimeter of the underground repository. They would be designed to be unnatural-looking so they would draw attention, but not be misconstrued as memorials of honor.

Nearby populations

 AmargosaValley.comIrrigated alfalfa agriculture in Amargosa Valley, Nevada. Source: AmargosaValley.comThe agricultural community of Amargosa Valley, which stretches from the southern boundary of the Nevada Test Site to the California border,  is centered about 18 miles south of Yucca Mountain. Armagosa Valley has a population of approximately 1,400.

On the northern edge of Amargosa Valley, about 12 miles south of Yucca Mountain is Lathrop Wells at the intersection of U.S. Route 95 and Nevada Route 373.  It is where the closest residents to Yucca Mountain live. There are about 15 people who live there.

The major sources of employment, farming, tourism, and government, are in and around Amargosa Valley. The closest larger town is Pahrump. It is approximately 55 miles from Yucca Mountain with about 29,000 people. The closest metropolitan area is Las Vegas, with a population of more than 1.2 million is located approximately 100 miles southeast of Yucca Mountain

Radiation Standards

In September 2008 the U.S. Environmental Protection Agency (EPA) established its final radiation standards for the proposed spent nuclear fuel and high-level radioactive waste disposal facility at Yucca Mountain

EPA is required to set standards consistent with the findings and recommendations of the National Academy of Sciences (NAS) and satisfy a July 2004 court decision to extend the standards' duration. EPA states that the Yucca Mountain standards are in line with approaches used in the international radioactive waste management community. The final standards will:

  • Set an individual protection standard for an overall dose limit of 15 millirem per year for residents living in the vicinity of Yucca Mountain during and up to 10,000 years after the repository closes. The overall annual dose limit takes into account exposure through all pathways. After 10,000 years through the period of geologic stability (out to 1 million years) the individual-protection standard is set at 100 mrem/yr.
  • Set an human intrusion standard for a dose limit of 15 millirem per year during and up to 10,000 years after the repository closes. It takes into account releases caused by a borehole going through a waste container and into the underlying ground water. After 10,000 years through the period of geologic stability (out to 1 million years) the standard is set at 100 mrem/yr.
  • Require the DOE to consider the effects of climate change, earthquakes, volcanoes, and corrosion of the waste packages to safely contain the waste during the 1 million-year period; and
  • Be consistent with the recommendations of the NAS by establishing a radiological protection standard for this facility at the time of peak dose up to 1 million years after disposal.

Radiation exposures from a repository are estimated by the Department of Energy as follows:

  • During the first 10,000 years following the closing of the proposed repository, persons living in Amargosa Valley would receive little or no increase in radiation exposure from the repository. (This community is referenced because water from Yucca Mountain flows toward the Amargosa Valley. Water is expected to be the vehicle that would move radioactive particles from a repository to the water table and from there to contact with people and the environment.)
  • The Department estimates the maximum exposure to occur some 300,000 years after the repository is closed. At that time, it is possible that some people living in the Amargosa Valley could receive an additional 260 millirem per year. This would bring their total radiation dose to around 660 millirem per year.

Human exposure to radiation varies from natural sources, such as radon and ultraviolet radiation from the sun, and other sources, such as medical X-rays. The average annual radiation exposure from both naturally occurring and manmade sources for a person living in the United States has been estimated to be 360 millirem per year.  Thus, to put the estimated repositpry dose in perspective, 660 millirem is somewhat higher than the 360 millirem national average on a yearly basis but well below levels received by people living in other parts of the United States.

Cost

In 2008 the DOE issued a revised total cost estimate of the repository. The latest estimate puts the cost of research, construction and operation of the geologic repository over a 150 year period - from when work started in 1983 through to the facility's expected closure and decommissioning in 2133 - at $96.2 billion (in 2007 dollars). This is a 67% increase on the previous published estimate in 2001 of $57.5 billion. Excluding inflation, the new estimate increased 38% to $79.3 billion.

The new estimated cost includes some $13.5 billion that has already spent on the project; $54.8 billion for the construction, operation and decommissioning of the repository; $19.5 billion for transportation of the used fuel; and, $8.4 billion for other program activities.  The DOE said that the new cost estimate reflects a 30% increase in the amount of used nuclear fuel from commercial nuclear power reactors to be disposed of in the repository. In 2000, it was estimated that some 83,800 tonnes heavy metal (tHM) of used fuel would be stored, but the latest estimates put the quantity at 109,300 tHM. This increased amount - resulting from existing and anticipated operating licence renewals at US reactors - would extend the transportation period by 16 years and the emplacement period by 25 years.

The total cost of constructing and operating the repository is divided between utility ratepayers and taxpayers, with ratepayers estimated to pay just over 80%, or $77.3 billion. The DOE  has determined that the fee currently paid to the government for the Nuclear Waste Fund by nuclear utilities of 0.1¢ per kWh of electricity they generated remains adequate to cover the nuclear utility customers' share of the total costs. It is therefore not proposing a change in this fee.

Opposition

Nevadans protest against the proposed Yucca Mountain repository at the state's capital in Reno.Nevadans protest against the proposed Yucca Mountain repository at the state's capital in Reno.The Yucca Mountain project is widely opposed in Nevada and is a hotly debated national topic. A 2006 public opinion survey conducted by the Governor's office showed that opposition to the program is very high. Statewide, 72.4% of Nevadans oppose locating a high-level nuclear waste repository at Yucca Mountain and would vote against it if given the opportunity. Only 23.9% support the project. The 2006 survey results are consistent with results from prior surveys dating back to 1989.  Many Nevadans' opposition stemmed from the so-called "Screw Nevada Bill," the 1987 legislation halting study of Hanford and Texas as potential sites for the waste before conclusions could be met.

Other individuals and organizations question the quality and accuracy of the scientific assessment of the site done by the DOE and its contractors. Of particular concern is the possible risk associated with the contaimination of groiundwater with radiaiton and the relase of radiaiton from earthquakes and other tectonic actvity. Critics charge the DOE science understimates such risks, and may be biased because the DOE has a vested interest in the project going forward.

Following the 2006 mid-term Congressional elections, Nevada Senator Harry Reid, a long time opponent of the repository, became the Senate Majority Leader, putting him in a position to greatly affect the future of the project. Reid has said that he would continue to work to block completion of the project, and is quoted as having said: "Yucca Mountain is dead. It'll never happen."

The DOE strongly rejects the claim that its scientific assessments are inadequate and/or in error, describing the Yucaa Mountain as the most intensively investgated site on Earth.
 

Litigation

The State of Nevada has filed multiple lawsuits against the federal government regarding the Yucca Mountain Project. Most of these lawsuits were consolidated into four cases that were heard at the District of Columbia Court of Appeals on January 14, 2004. The judges dismissed most of Nevada's claims, but they did rule in favor of the State's complaint against radiation standards for the nuclear waste repository. In September 2008, the EPA released revised radiation standards that it claims are consistent with the findings and recommendations of the National Academy of Sciences (NAS), and that satisfy the 2004 court decision to extend the standards' duration out to 1,000,000 years.

Sources

  • National Academy of Sciences (NAS), National Research Council, Going the Distance? The Safe Transport of Spent Nuclear Fuel and High-level Radioactive Waste in the United States, National Academies Press, Washington, DC (2006
  • Office of Civilian Radioactive Waste Management, Yucca Mountain DepositoryU.S. Department of Energy, Accessed 30 November 2008.
  • Wikipedia Contributors, Yucca Mountain nuclear waste repository, Wikipedia The Free Encyclopedia, Accessed 30 November 2008.
  • World Nuclear News, Yucca Mountain cost estimate rises to $96 billion, 06 August 2008.
  • Yucca Mountain Information Office, Eureka County, Nevada, Accessed 30 November 2008.

 

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