| Waste Isolation Pilot Plant | |
| WIPP | |
|
WIPP, a geological repository for radioactive waste
|
|
| Country | United States |
|---|---|
| State | New Mexico |
| County | Eddy County |
| Nearest city | Carlsbad |
| Location | 42 km east of Pecos River |
| - elevation | 1,038 m (3,406 ft) |
| - coordinates | |
| Geology | Permian, Salado Formation |
| Date | 26 March 1999 |
| Management | United States Department of Energy |
| Easiest access | New Mexico State Road 128 |
|
Schematic of WIPP facility
|
|
| Website: DOE: Waste Isolation Pilot Plant | |
The Waste Isolation Pilot Plant, or WIPP, is the world's third deep geological repository (after closure of Germany's Repository for radioactive waste Morsleben and the Schacht Asse II Salt Mine) licensed to permanently dispose of transuranic radioactive waste for 10,000 years[1] that is left from the research and production of nuclear weapons. It is located approximately 26 miles (42 km) east of Carlsbad, New Mexico, in eastern Eddy County.
Contents |
The Waste Isolation Pilot Plant is located in the Delaware Basin of New Mexico. This 600-meter deep salt basin was formed during the Permian Era approximately 250 million years ago.[2] An ancient sea once covering the area evaporated and left behind a nearly impermeable layer of salt that over time was covered by 300 meters of soil and rock.[3] The Delaware Basin was originally believed to be geologically similar to other basins created by evaporated seas. Geologists expected to find horizontal layers of salt and rock when drilling. However, as drilling in the salt beds began in 1975, geologists discovered that disturbances had moved the salt layer into a nearly vertical position.[3] The geological complexity of the basin has proven to be very problematic, often causing the hollowed-out caverns to be unstable.[4]
The United States Department of Energy (DOE) began studying sites for construction of the Waste Isolation Pilot Plant (WIPP) near Carlsbad, New Mexico in 1973, after the abandonment of a similar site in Lyons, Kansas. The Kansas site, tentatively selected by the Atomic Energy Commission (AEC) in 1970, was deemed unusable due to unmapped oil and gas wells located in the area. These uncharted wells were believed to potentially compromise the ability of the planned facility to contain nuclear waste. As a result of these concerns, the DOE relocated the site of the proposed nuclear waste repository to the Delaware Basin salt beds located in New Mexico.[3]
Exact placement of the construction site in the Delaware Basin changed multiple times due to do safety concerns. Brine deposits located throughout the Delaware Basin posed a major safety problem. The brine was first discovered when a 1975 drilling released a pressurized deposit of the liquid.[3] Constructing the plant near one of these deposits would severely compromise the facility’s safety. The highly corrosive brine could leak into the repository and destroy the steel waste containers, thus exposing the radioactive waste to the environment. The polluted brine could then seep into the surrounding areas and contaminate drinking wells and soil. After multiple relocations, a final site was selected. The site is located approximately 40 km east of Carlsbad.[3]
In order to address growing public unrest concerning construction of the WIPP, the New Mexico Environmental Evaluation Group (EEG) was created in 1978.[3] This group, charged with overseeing the WIPP, verified statements, facts, and studies conducted and released by the DOE regarding the facility. The stewardship this group provided effectively lowered public fear and let the facility progress with little public opposition in comparison to similar facilities around the nation such as Yucca Mountain in Nevada.
The EEG, in addition to acting as a check for the government agencies overseeing the project, acted as a valuable advisor. In a 1981 drilling, pressurized brine was again discovered. The site was set to be abandoned when the EEG stepped in and suggested a series of tests on the brine and the surrounding area. These tests were conducted and the results showed that the brine deposit was relatively small and was isolated from other deposits. Drilling in the area was deemed safe due to these results. This saved the project valuable money and time by preventing a drastic relocation.[3]
In 1979 Congress authorized construction of the facility.[5] In addition to formal authorization, Congress redefined the level of waste to be stored in the WIPP from high temperature to transuranic, or low level, waste. Transuranic waste often consists of materials which have come in contact with radioactive substances such as plutonium and uranium. This often includes gloves, tools, rags, and assorted machinery often used in the production of nuclear fuel and weapons.[2] Although much less potent than nuclear reactor byproducts, this waste still remains radioactive for approximately 24,000 years.[4] This change in classification led to a decrease in safety parameters for the proposed facility, allowing construction to continue at a faster pace.[3]
The first extensive testing of the facility was due to begin in 1988. The proposed testing procedures involved interring samples of low level waste in the newly constructed caverns. Various structural and environmental tests would then be performed on the facility to verify its integrity and to prove its ability to safely contain nuclear waste.[6] Opposition from various external organizations delayed actual testing into the early 1990s. Attempts at testing were resumed in October 1991 with US Secretary of Energy James Watkins announcing that he would begin transportation of waste to the WIPP.[4]
Despite apparent progress on the facility, construction still remained costly and complicated. Originally conceptualized in the 1970s as a warehouse for waste, the repository now had regulations similar to those of nuclear reactors. As of December 1991, the plant had been under construction for 20 years and was estimated to have cost over one billion dollars.[4] At the time, WIPP officials reported over 28 different organizations claiming authority over operations of the facility.[4]
In November 1991, a federal judge ruled that Congress must approve WIPP before any waste, even for testing purposes, was sent to the facility. This indefinitely delayed testing until Congress gave its approval.[4] The 102nd United States Congress passed legislation allowing use of the WIPP. The House of Representatives approved the facility on the 6th of October, 1992 and the Senate passed a bill allowing the opening of the facility on October 8 of the same year.[7] The bill was met with much opposition in the Senate. Senator Richard H. Bryan fought the bill based on safety issues that concerned a similar facility located in Nevada, the state for which he was serving as senator. His efforts almost prevented the bill from passing. New Mexico senators Pete V. Domenici and Jeff Bingaman effectively reassured Senator Bryan that these issues would be addressed in the 103rd Congress. The final legislation provided safety standards requested by the House and an expedited timeline requested by the Senate.[7]
The final legislation mandated that the Environmental Protection Agency (EPA) issue revised safety standards for the facility. It also required the EPA to approve testing plans for the facility within ten months. The legislation stated that the security standards mandated in the bill were only applicable to the WIPP in New Mexico and not to other facilities in the United States. This clause caused Senator Bryan to oppose the bill, as he wanted safety standards mandated by the bill to apply to the facility in Nevada as well.[7]
In 1994, Congress ordered Sandia National Laboratories to begin an extensive evaluation of the facility against the standards set forth by the EPA. Evaluation of the facility continued for four years, resulting in a cumulative total of 25 years of evaluation. In May 1998, the EPA concluded that there was “reasonable expectation” that the facility would contain the vast majority of the waste interred there.[3]
The first nuclear waste arrived to the plant on March 26, 1999. This waste shipment was from Los Alamos National Laboratory, a major nuclear weapons research and development facility located north of Albuquerque, New Mexico. Another shipment followed on April 6 of the same year. These shipments marked the beginning of plant operations.[8] As of December 2010, the plant had received and stored 9,207 shipments (72,422 cubic meters) of waste. The majority of this waste was transported to the facility via rail-road or truck.[2] The final facility contains a total of 56 storage rooms located approximately 650 meters underground. Each room is 100 yards in length.[6] The plant is estimated to continue accepting waste for 25 to 35 years and is estimated to cost a grand total of 19 billion dollars.[8]
Following the interment of waste in the facility, the storage caverns will be collapsed and sealed with 13 layers of concrete and soil. Salt will then seep into and fill the various fissures and cracks surrounding the casks of waste. After approximately 75 years, the waste will be completely isolated from the environment.[9] A major concern confronting planners of the plant is future human intrusion into the plant. It is expected that the location of the facility will be forgotten over the 10,000 year lifetime of the facility and that future generations will accidentally penetrate the facility and release radiation. In order to maintain the integrity of the facility, scientists were required to create a warning system for future generations. In 1992 the DOE assembled a 12 person panel of archaeologists, linguists, anthropologists, material scientists, astronomers, artists, and architects to design the warning system. This team discussed ideas such as physical barriers, psychological deterrents (such as large concrete spikes), and linguistic warnings.[10] The final warning system is a combination of the many ideas discussed.[11]
Waste that is to be disposed of at WIPP must meet certain "waste acceptance criteria". It accepts transuranic waste generated from DOE activities. The waste must have radioactivity exceeding 100 nCi per gram from TRUs that produce alpha radiation with a half life greater than 20 years. This criterion includes plutonium, uranium, americium, and neptunium among others. Mixed waste contains both radioactive and hazardous constituents, and WIPP first received mixed waste on September 9, 2000. Mixed waste is joint-regulated by the EPA and the New Mexico Environment Department.
The containers may also contain a limited amount of liquids. The energy released from radioactive materials will dissociate water into hydrogen and oxygen. This could then create a potentially explosive environment inside the container. The containers must be vented, as well, to prevent this from happening.
Waste is placed in rooms 2,150 feet (655 m) underground that have been excavated within a 3,000 foot (1000 m) thick salt formation (Salado and Castile Formations) where salt tectonics has been stable for more than 250 million years. Because of plasticity effects, salt and water will flow to any cracks that develop, a major reason why the area was chosen as a host medium for the WIPP project. Because drilling or excavation in the area will be hazardous long after the area is actively used, there are plans to construct markers to deter inadvertent human intrusion for the next ten thousand years.[12][13][14]
The Salado Formation is a massive bedded salt deposit (>99% NaCl) that has a simple hydrogeology. Because massive NaCl is somewhat plastic and holes close under pressure, the rock becomes non-porous by effectively closing pores and fractures. This has a significant effect on the overall hydraulic conductivities (water permeabilities) and molecular diffusion coefficients. These are on the order of ≤10−14 m/s and ≤10−15 m2/s respectively.[15][16]
Since 1991, the DOE has been working with a team of linguists, scientists, science fiction writers, anthropologists, and futurists to come up with a warning system. The markers, called "passive institutional controls", will include an outer perimeter of 32, 25-foot (7.6 m)-tall granite pillars built in a four-mile (6 km) square. These pillars will surround an earthen wall, 33 feet (10 m) tall and 100 feet (30 m) wide. Enclosed within this wall will be another 16 granite pillars. At the center, directly above the waste site, will sit a roofless, 15-foot (4.6 m) granite room providing more information. The team intends to etch warnings and informational messages into the granite slabs and pillars. This information will be recorded in the six official languages of the United Nations (English, Spanish, Russian, French, Chinese, Arabic) as well as the Native American Navajo language native to the region, with additional space for translation into future languages. Pictograms are also being considered, such as stick figure images and the iconic "The Scream" from Edvard Munch's painting. Complete details about the plant will not be stored on site; instead, they would be distributed to archives and libraries around the world. The team plans to submit their final plan to the U.S. Government by around 2028.[17]