Key Issues
Disposal of Low-Level Radioactive Waste
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Safekeeping: Disposal of Low-Level Waste
The first commercial low-level waste disposal site was established in 1963. By 1971, there were six sites: West Valley, N.Y.; Sheffield, Ill.; Maxey Flats, Ky.; Richland, Wash.; Beatty, Nev.; and Barnwell, S.C. The first three are now closed, and Beatty has stopped accepting low-level waste. There were difficulties during the operation of West Valley, Sheffield and Maxey Flats, because they were not sited or designed under the rigorous requirements in place today. But no public health problem was ever identified with any of the sites. Some practices used at Beatty—for ex-ample, the disposal of liquid waste—would not be acceptable today. Although small quantities of mobile radionuclides have been detected, the groundwater has not been affected, and the site will not pose a hazard to the public. Today, scientists and engineers have developed modern, improved waste disposal technologies, based on what has been learned at operating sites.
The Barnwell and Richland sites are still operating safely, under strict government regulations. The facility in Utah also began accepting certain commercial low-activity low-level waste (Class A) in 1995.
The NRC and the states govern the siting, operation and closure of all low-level waste disposal facilities. The purpose of low-level waste disposal is to isolate the waste from people and the environment. The NRC has set forth requirements to protect people from releases from the site, prevent inadvertent intrusion into the waste, protect workers during operation and ensure the stability of the site after closure.
The NRC regulations ensure that Class A low-level waste is contained for up to 100 years, Class B waste for up to 300 years and Class C waste for up to 500 years. Scientists and engineers have the knowledge and ability to design and build facilities to contain the waste safely for the required period and longer.
The NRC has set forth technical requirements for low-level waste disposal sites. They require, among other things, that natural resources in the area, such as wildlife preserves, be avoided; the site must be sufficiently isolated from groundwater and/or surface water; and the site must not be in an area of geological activity (such as volcanoes or earthquakes).
Regardless of design, all low-level waste disposal sites use a series of natural and engineered barriers to prevent radioactivity from reaching the biosphere. There are several designs for building disposal facilities.
Shallow Land Burial
This method was used by all U.S. low-level waste disposal facilities until 1995. Waste containers are placed in long, lined trenches 25 or more feet deep. The trenches are covered with a clay cap or other low-permeability cover, gravel drainage layers and a topsoil layer. They then are contoured and replanted with vegetation for drainage and erosion control. In addition, an intrusion barrier, such as a thick concrete slab, is added to Class C waste trenches. The sites are carefully monitored to ensure performance in compliance with the regulations. Facilities are sited in an area away from surface water and where travel of any groundwater is slow. The sites are monitored to ensure that there is no leakage.
Modular Concrete Canister Disposal
This method consists of individual waste containers placed within concrete canisters, which are then disposed of in shallow land sites. The array of canisters has an earthen cover. This additional engineered barrier system has been used at the Barnwell, S.C., facility since 1995.
Belowground Vault
This type of disposal uses a sealed structure built of masonry blocks, fabricated metal, concrete or other materials that provide a barrier to prevent waste migration. It has a drainage channel, a clay top layer and a concrete roof to keep water out, a porous backfill, and a drainage pad for the concrete vault. This design has been used successfully at a DOE disposal site.
Aboveground Vault or Engineered Berm
This is a reinforced-concrete building that provides isolation on the earth’s surface. Its walls and roof are two to three feet thick, and it has a sloping roof to aid water runoff. Some Canadian utilities use similar aboveground vaults for storing low-level waste for later disposal. For low-activity radioactive waste, aboveground engineered berms pro-vide the same isolation as shallow land burial. Envirocare of Utah uses aboveground engineered berms.
Earth-Mounded Concrete Bunkers
In these facilities, wastes are placed in belowground, concrete monoliths, and less radioactive waste is placed on top of the monoliths to create the mounds. The bunker is equipped with a drainage system and covered with impermeable clay and topsoil, giving the facility a rounded shape. These have been successfully used in France for at least two decades.
Generally, all costs of site development, operation and long-term monitoring are paid by the generators of the waste.
Safekeeping: Disposal of Low-Level Waste
The first commercial low-level waste disposal site was established in 1963. By 1971, there were six sites: West Valley, N.Y.; Sheffield, Ill.; Maxey Flats, Ky.; Richland, Wash.; Beatty, Nev.; and Barnwell, S.C. The first three are now closed, and Beatty has stopped accepting low-level waste. There were difficulties during the operation of West Valley, Sheffield and Maxey Flats, because they were not sited or designed under the rigorous requirements in place today. But no public health problem was ever identified with any of the sites. Some practices used at Beatty—for ex-ample, the disposal of liquid waste—would not be acceptable today. Although small quantities of mobile radionuclides have been detected, the groundwater has not been affected, and the site will not pose a hazard to the public. Today, scientists and engineers have developed modern, improved waste disposal technologies, based on what has been learned at operating sites.
The Barnwell and Richland sites are still operating safely, under strict government regulations. The facility in Utah also began accepting certain commercial low-activity low-level waste (Class A) in 1995.
The NRC and the states govern the siting, operation and closure of all low-level waste disposal facilities. The purpose of low-level waste disposal is to isolate the waste from people and the environment. The NRC has set forth requirements to protect people from releases from the site, prevent inadvertent intrusion into the waste, protect workers during operation and ensure the stability of the site after closure.
The NRC regulations ensure that Class A low-level waste is contained for up to 100 years, Class B waste for up to 300 years and Class C waste for up to 500 years. Scientists and engineers have the knowledge and ability to design and build facilities to contain the waste safely for the required period and longer.
The NRC has set forth technical requirements for low-level waste disposal sites. They require, among other things, that natural resources in the area, such as wildlife preserves, be avoided; the site must be sufficiently isolated from groundwater and/or surface water; and the site must not be in an area of geological activity (such as volcanoes or earthquakes).
Regardless of design, all low-level waste disposal sites use a series of natural and engineered barriers to prevent radioactivity from reaching the biosphere. There are several designs for building disposal facilities.
Shallow Land Burial
This method was used by all U.S. low-level waste disposal facilities until 1995. Waste containers are placed in long, lined trenches 25 or more feet deep. The trenches are covered with a clay cap or other low-permeability cover, gravel drainage layers and a topsoil layer. They then are contoured and replanted with vegetation for drainage and erosion control. In addition, an intrusion barrier, such as a thick concrete slab, is added to Class C waste trenches. The sites are carefully monitored to ensure performance in compliance with the regulations. Facilities are sited in an area away from surface water and where travel of any groundwater is slow. The sites are monitored to ensure that there is no leakage.
Modular Concrete Canister Disposal
This method consists of individual waste containers placed within concrete canisters, which are then disposed of in shallow land sites. The array of canisters has an earthen cover. This additional engineered barrier system has been used at the Barnwell, S.C., facility since 1995.
Belowground Vault
This type of disposal uses a sealed structure built of masonry blocks, fabricated metal, concrete or other materials that provide a barrier to prevent waste migration. It has a drainage channel, a clay top layer and a concrete roof to keep water out, a porous backfill, and a drainage pad for the concrete vault. This design has been used successfully at a DOE disposal site.
Aboveground Vault or Engineered Berm
This is a reinforced-concrete building that provides isolation on the earth’s surface. Its walls and roof are two to three feet thick, and it has a sloping roof to aid water runoff. Some Canadian utilities use similar aboveground vaults for storing low-level waste for later disposal. For low-activity radioactive waste, aboveground engineered berms pro-vide the same isolation as shallow land burial. Envirocare of Utah uses aboveground engineered berms.
Earth-Mounded Concrete Bunkers
In these facilities, wastes are placed in belowground, concrete monoliths, and less radioactive waste is placed on top of the monoliths to create the mounds. The bunker is equipped with a drainage system and covered with impermeable clay and topsoil, giving the facility a rounded shape. These have been successfully used in France for at least two decades.
Generally, all costs of site development, operation and long-term monitoring are paid by the generators of the waste.
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