Radioactive Waste

Radioactive waste (or nuclear waste) is a material deemed no longer useful that has been contaminated by or contains radionuclides. Radionuclides are unstable atoms of an element that decay, or disintegrate spontaneously, emitting energy in the form of radiation. Radioactive waste has been created by humans as a by-product of various endeavors since the discovery of radioactivity in 1896 by Antoine Henri Becquerel. Since World War II, radioactive waste has been created by military weapons production and testing; mining; electrical power generation; medical diagnosis and treatment; consumer product development, manufacturing, and treatment; biological and chemical research; and other industrial uses.

There are approximately five thousand natural and artificial radionuclides that have been identified, each with a different half-life. A half-life is a measure of time required for an amount of radioactive material to decrease by one-half of its initial amount. Half-life values for each known radionuclide are unique. The half-life of a radionuclide can vary from fractions of a second to millions of years. Some examples of radionuclides with a range of different half-lives include sodium-26 (half-life of 1.07 seconds), hydrogen-3 (half-life of 12.3 years), carbon-14 (half-life of 5,730 years), and uranium-238 (half-life of 4.47 billion years). The decay process of a radionuclide is the
mechanism by which it spontaneously releases its excess energy. Typical mechanisms for radioactive decay are alpha, beta, and gamma emission. Alpha decay is a process that is usually associated with heavy atoms, such as uranium-238 and thorium-234, where excess energy is given off with the ejection of two neutrons and two protons from the nucleus. Beta decay involves the ejection of a beta particle, which is the same as an electron, from the nucleus of an excited atom. A common example of a beta-emitter found in radioactive waste is strontium-90. After an alpha or beta decay, the nucleus of an atom is often in an excited state and still has excess energy. Rather than releasing this energy by alpha or beta decay, energy is lost by gamma emission—a pulse of electromagnetic radiation from the nucleus of an atom.

Everything on Earth is exposed to radiation. However, exposure to radiation at levels greater than natural background radiation can be hazardous. Exposure to certain high levels of radiation, such as that from high-level radioactive waste, can even cause death. Radiation exposure can also cause cancer, birth defects, and other abnormalities, depending on the time of exposure, amount of radiation, and the decay mechanism. High-level radioactive waste from nuclear reactors can be hazardous for thousands of years. Radioactive waste can be categorized by its source or point of origin. Because of this, the governments of many nations have developed waste classification systems to regulate the management of radioactive waste within their borders. The proper treatment, storage, and disposal of radioactive waste are prescribed based on the waste classification system defined in a nation's laws, rules, and regulations. The table outlines common categories of radioactive waste.

Radioactive Waste Description

Radioactive waste can vary greatly in its physical and chemical form. It can be a solid, liquid, gas, or even something in between, such as sludge. Any given radioactive waste can be primarily water, soil, paper, plastic, metal, ash, glass, ceramic, or a mixture of many different physical forms. The chemical form of radioactive waste can vary as well. Radioactive waste can contain radionuclides of very light elements, such as radioactive hydrogen (tritium), or of very heavy elements, such as uranium. Radioactive waste is classified as high, intermediate, or low level. Depending on the radionuclides contained in it, a waste can remain radioactive from seconds to minutes, or even for millions of years.

Radioactive Waste Management

Radioactive waste management includes the possession, transportation, handling, storage, and ultimate disposal of waste. The safe management of radioactive waste is necessary to protect public health. If handled improperly, potential exposures of humans to high-level radioactive waste can be dangerous, even deadly. Some radioactive wastes such as certain types of transuranic waste can cause biological effects in humans only if the radionuclides contained in the waste are directly inhaled or ingested. Most low-level radioactive wastes can be handled by humans without any measurable biological effects. Nevertheless, good handling practices of all radioactive materials and waste should be the goal to provide optimum protection to humans and the environment. There have been historic practices associated with the use of radioactive material where workers were unaware of potential risks. The radium watch dial painters of the 1920s illustrate the health effects that can be associated with improper handling practices. The painters experienced high occurrences of cancer of the larynx and tongue due to ingestion of radium.

The transportation of radioactive waste can occur via roadway, aircraft, ship/barge, and rail. The classification and physical size of radioactive waste dictate the method of transport, the packaging required, and the labeling necessary to allow for the shipment of a specific waste. There are international transportation requirements for radioactive waste, as well as more specific regulations in individual countries.

Radioactive Waste Disposal

Various methods to manage and dispose of radioactive waste have been considered. Proposed management and disposal methods have included the

following scenarios: shallow land burial; engineered disposal vaults; vertical shafts drilled into granite, salt, basalt, or volcanic rock; disposal cavities mined into specific rock formations such as salt; deeper-earth disposal into the submantle layer; above-ground isolation in engineered, concrete structures; recycling and reuse of waste material; radionuclide transmutation into nonradioactive material; ocean and seabed disposal; ice-sheet disposal; isolation disposal on a remote island; and even disposal in space.

Most of the civilian high-level radioactive waste throughout the world is currently being stored at nuclear power reactor sites. The spent nuclear fuel generated from the 103 operating civilian power reactors in the United States is currently being stored on-site at the point of generation. In Europe, prior to on-site storage, spent fuel is first sent to either the Sellafield site in the United Kingdom or the La Hague site in France to be reprocessed in order to recover usable fuel. No reprocessing of commercial spent fuel is being conducted in the United States. In the United States, spent fuel and other high-level radioactive waste awaits the construction of a central, permanent repository. It is currently stored in spent fuel pools or, in some cases, in dry casks. Spent fuel pools are water-filled, lead-lined chambers that are adjacent to reactors on civilian power reactor sites. Dry-cask storage has become necessary in some cases where the on-site spent fuel pools have reached capacity. The Office of Civilian Radioactive Waste Management at the U.S. Department of Energy (DOE) is charged with developing this federal repository. Amid local opposition, Yucca Mountain, Nevada, is presently under study to evaluate its suitability as a central repository for all U.S. high-level radioactive waste. The Yucca Mountain site has been officially designated by President George W. Bush and Congress for full-scale studies. There has been further emphasis placed on the security of spent fuel, and in general on nuclear reactor sites following the September 11, 2001, terrorist attacks. Nuclear reactor sites that store spent fuel have been identified as possible terrorist targets and, therefore, have been subject to heightened security and debate over potential vulnerabilities. France, Germany, the United Kingdom, and Japan also have plans to develop centralized repositories for high-level radioactive waste at various times in the future.

Transuranic waste generated by the DOE has an operational final repository. The Waste Isolation Pilot Project located near Carlsbad, New Mexico, accepts transuranic waste and mixed transuranic waste (i.e., transuranic waste that also has a hazardous waste component) from federal facilities throughout the United States. This facility is comprised of disposal cavities mined into a salt formation some 2,150 feet underground.

The disposal method used in the 1960s and 1970s for low-level radioactive waste was shallow land burial in earthen trenches. The infiltration of water into these trenches resulted in the migration or movement of certain radionuclides into surrounding soil and groundwater. To respond to such problems, engineered disposal units have been developed to replace shallow land burial, utilizing enhanced cover systems to reduce the potential for water infiltration. The trial-and-error nature of early radioactive waste disposal sites has rendered new facility development a slow and cautious process.

Historical Perspective

The first commercial site for the disposal of low-level radioactive waste was opened in Beatty, Nevada, in 1962. Within the next ten years, five more sites opened in the United States: in Washington, Illinois, South Carolina, New York, and Kentucky. Private companies operated these sites on land leased from state governments. Prior to 1979, the DOE routinely used commercial sites for the disposal of federal waste.

Migration problems at commercial disposal sites in the United States were first discovered in the late 1960s. Four of the six commercial low-level radioactive waste disposal sites in the United States closed. Three of the four sites that closed developed leaks due to erosion by surface water, subsidence on tops of trenches, or buried waste immersed in water. Several of these locations became federal Superfund sites due to radionuclides migrating beyond the disposal trenches, complicated by the presence of hazardous waste within the same facilities.

The historical problems experienced with commercial radioactive waste disposal in the United States resulted in the development of new regulatory requirements for site selection, construction parameters, operating practices, and waste-acceptance criteria at future disposal sites. A new U.S. disposal regulation, Title 10, Code of Federal Regulations, Part 61, "Licensing Requirements for Land Disposal of Radioactive Wastes" was introduced in 1982. This regulation outlines the requirements necessary to ensure public health, safety, and the long-term protection of the environment. Since the development of this new regulation in the United States, only one site, in Clive, Utah, has been licensed and opened for disposal of low-level radioactive waste.

Summary

Radioactive waste is being generated in the United States and throughout the world as a result of research, mining, electricity production, nuclear weapons production, and medical uses. There are many possible beneficial activities due to the use of radioactive material. Laws, rules, and regulations are made on a global scale to help ensure the safe handling of radioactive waste to protect human and environmental health. However, the question of the safe final deposition of all radioactive waste generated worldwide is still problematic.

see also Cleanup; Energy, Nuclear; Superfund; Waste, Transportation of; Yucca Mountain.

Bibliography

league of women voters education fund. (1993). the nuclear waste primer. new york: lyons & burford, publishers.

murray, raymond l. (1994). understanding radioactive waste, 4th edition. columbus, oh: battelle press.

parrington, josef r.; knox, harold d.; breneman, susan l.; baum, edward m.; and feiner, frank. (1996). nuclides and isotopes, 15th edition. san jose, ca: general electric company.

internet resources

international atomic energy agency. "world atom." available from http://www.iaea.or.at/worldatom.

u.s. department of energy, office of civilian radioactive waste management. "the yucca mountain project." available from http://www.ymp.gov.

u.s. nuclear regulatory commission. "radioactive waste." available from http://www.nrc.gov/waste.html.

waste link directory. "guide to radioactive waste." available from http://www.radwaste.org/general.htm.

Susan M. Jablonski

Radioactive Waste

Types of radioactive waste

Storage of radioactive waste

Transportation of radioactive waste

Treatment of radioactive waste

Disposal of radioactive waste

Current problems in radioactive waste

Resources

Radioactive waste is generated during the production of electricity by nuclear reactors and by the eventual disposal of the reactors and their facilities, during the manufacturing and disposal of nuclear weapons and machines used in medical diagnosis and treatment, by academic and industrial research, and by certain industrial processes. Radioactive waste produces ionizing radiation, which can damage or destroy living tissues. Ionizing radiation transfers energy when it encounters biochemicals, causing them to become electrically charged (ionized), which can damage their essential metabolic function.

Unlike conventionally toxic chemicals, the degree of danger from radioactive waste decreases over time. The half-life of a radioactive substance (or radioisotope) is the time required for one-half of an initial quantity to decay to other isotopes. Each radioisotope has a unique half-life, which can be only fractions of a second long, or as great as billions of years. The longer the half-life of a radioisotope, the longer is the period for which it must be safely stored or disposed until it is no longer hazardous.

Types of radioactive waste

Radioactive wastes are grouped into three categories: high-level waste, low-level waste, and transuranic waste. High-level waste emits intense levels of ionizing radiation for a relatively short time, and then emits lower levels for a much longer time. Most high-level waste is used nuclear fuel rods, which must be removed from the reactor core about every two to four years. Large quantities of high-level wastes are also associated with the production and disposal of nuclear weapons. In 2000, about 44,000 tons (40,000 tonnes) of spent fuel were stored at commercial nuclear power sites in the United States, a quantity expected to rise to 116,000 tons (105,000 tonnes) by 2035.

Low-level waste emits small amounts of ionizing radiation, usually for a long time, and it tends to be a high-volume waste. Low-level waste is produced from a variety of sources, such as filters and other cleaning material from nuclear plants, and used low-level radioisotopes from hospitals, universities, and industry. For example, in nuclear generating stations, tiny quantities of some radioactive materials may leak from the reactor. To protect the workers and the ambient environment, this radioactivity is removed with filters, which must periodically be replaced, becoming low-level waste.

Transuranic waste results primarily from the fabrication of plutonium as well as research activities at defense installations. Transuranics are elements, not found in nature, that are heavier than uranium. Most transuranics have special properties that increase the probability of causing damage to living tissue. Transuranic elements are found in both high-level and low-level radioactive waste. They can be separated from low-level waste, and are then treated as high-level waste.

Storage of radioactive waste

Storage can be defined as “a method of containment with a provision for retrieval.” High-level and transuranic wastes are typically stored in on-site, deepwater storage ponds with thick, stainless steel-lined concrete walls. After about five years, the spent fuel has lost much of its radioactivity and can be moved into dry storage facilities. These are usually on-site, above-ground facilities in which the waste is stored in thick, concrete canisters.

Low-level waste is stored in concrete cylinders in shallow burial sites at nuclear plants or at designated waste sites. Since these wastes are not as much of a concern as high-level wastes, the regulations for their storage are not as strict. Basically, the waste must be covered and stored so that contact with ambient water is minimal.

Transportation of radioactive waste

The regulations for transporting radioactive waste are stringent due to the possibility of a transportation accident. Various containers are used for transporting specific kinds of waste. High-level waste has the most rigorous standards, and the containers in which it is shipped must be capable of withstanding tremendous pressure, impact, and heat, and must be waterproof. There have been accidents in North America involving trucks and trains carrying radioactive waste, but no significant amount of radioactivity has ever been released to the environment as a result.

Treatment of radioactive waste

High-level radioactive waste can be treated by fuel reprocessing, which separates still-useful fuel isotopes from the rest of the waste. The useful isotopes can then be sent to a fabrication plant, which produces new nuclear fuel. Some technologists view this strategy as an excellent alternative to long-term storage, since it is essentially a re-use practice as opposed to disposal. Fuel reprocessing plants exist in Britain, France, Japan, Germany, India, and Russia. The United States, Canada, Spain, and Sweden do not have reprocessing plants, and are planning on long-term storage of their spent fuel.

Low-level radioactive waste is commonly a high-volume material, which can often be reduced prior to storage, transport, or disposal. It can be concentrated by filtering and removing the liquid portion, so only the solid residue remains for disposal. Alternatively, the material may be solidified by fusing it into glass or ceramic, which are highly stable materials.

Disposal of radioactive waste

Radioactive waste disposal refers to the long-term removal of the waste, and is designed to have minimal contact with organisms and the ambient environment. The safe disposal of high-level and transuranic wastes from nuclear power plants and nuclear weapons facilities has been the center of vigorous debate for more than 50 years, and researchers and policy-makers have yet to come up with politically acceptable solutions.

The most widely supported plan involves the burial of high-level waste deep underground in a stable geological formation. Less-popular ideas include burial under a stable glacier, or dumping into a deep oceanic trench. Part of the problem with any of these ideas is that disposal requires that the site will be secure for tens of thousands of years. This probably exceeds the time for which present governmental and social institutions will persist, so far-future generations may have to deal with the high-level nuclear wastes of the present ones. Moreover, nature can be a changeable, unpredictable, and powerful force, so there are unknown risks associated with all disposal options, and long-term, absolute guarantees cannot be given.

From 1940 to 1970, most low-level wastes were placed into steel drums and dumped into the ocean or into pits on land. However, there has been inevitable leakage from the drums, and environmentalists and the public objected to this method of disposal. Since 1970, the United States has been disposing its low-level waste at government-regulated disposal sites. In June 1990, the U. S. Nuclear Regulatory Commission (NRC) proposed that low-level radioactive waste be handled as regular garbage, due to its supposed low health risk. Epidemiologists calculated that implementing this policy might have caused 2,500 American deaths, but the NRC believed this risk was acceptable because it would save the nuclear power industry many millions of dollars every year. However, this proposal did not fully take account of recent research indicating that low-level radiation risks may be about 30 times higher than previously estimated.

Current problems in radioactive waste

The biggest technological challenge facing the nuclear industry is the long-term, safe disposal of high-level waste. The current preferred disposal option is to bury it deep underground. The United States Department of Energy proposed in 1983 that nine sites in geologically diverse locations be studied for suitability as one of two potential waste repositories. In 1987, Congress amended the Nuclear Waste Policy Act to redirect the Department of Energy to focus site characterization activities only at Yucca Mountain, Nevada. Huge sums of money have been spent in planning for this disposal option, but it remains controversial and is not yet built. The Department of Energy does predict, however, that the site will be available for disposal activities in the year 2010.

Political and scientific disagreements between the State of Nevada and the federal government have delayed the process, as have arguments presented by environmental groups. Opponents have complained

KEY TERMS

Half-life— The time required for one-half of an initial quantity of a radioactive substance to disintegrate.

High-level waste— Waste that emits intense levels of ionizing radiation for a short time, and then lower levels for a much longer time.

Ionizing radiation— Radiation that can cause tissue damage or death.

Low-level waste— Waste that emits small amounts of ionizing radiation, often for a long time.

Radioisotope— A type of atom or isotope, such as strontium-90, that exhibits radioactivity.

Transuranic waste— A special category of waste produced during the fabrication of plutonium as well as research activities at defense installations, involving non-natural elements heavier than uranium.

that the site selection process has been dominated by political decision making rather than scientific reason. Technical concerns largely center on the geological stability of the area and the potential for water infiltration into the repository causing the release of radioactive material into the environment. Moreover, there are relatively young volcanoes nearby, several faults near the site, and the potential for climate change to cause groundwater levels to rise and inundate the repository horizon. Further complicating the issue is the fact that the proposed site lies adjacent to the Nevada Test Site (NTS), the location at which approximately one thousand nuclear weapons tests have been conducted. Some have argued that the extensive radioactive contamination associated with testing at the NTS makes the Yucca Mountain site more favorable for waste disposal. They suggest that the existing, uncontrolled contamination is unlikely to be significantly worsened by the proposed disposal of nuclear wastes in a controlled, engineered system and that localization of the wastes in a previously contaminated area is preferable to the contamination of a new site.

Despite the controversy, in February 2002, the Secretary of Energy recommended to the President (George W. Bush) that the Yucca Mountain site be selected as the nation’s high-level nuclear waste repository. The President followed the Secretary’s recommendation and approved the site, only to be vetoed by the governor of the State of Nevada. However, the U.S. Congress voted to override the veto in July 2002. The State of Nevada has since filed lawsuits to stop the project and will very likely fight the licensing application with the NRC prior to the receipt of waste and operation of the repository. It seems that the only certainty is that the safe, long-term disposal of high-level radioactive wastes will continue to be an extreme challenge for technologists, and for society. A Federal appeals court found in favor of the Environmental Protection Agency in July 2004, except for finding that the 10,000-year timeframe used by the EPA’s standards was too short to be supported by the findings of the National Academy of Sciences. As of 2006, no nuclear waste had yet been stored at Yucca Mountain and its fate was still uncertain.

See also Nuclear reactor; Radiation.

Resources

BOOKS

Macfarlane, Allison M., and Rodney C. Ewing. Uncertainty Underground: Yucca Mountain and the Nation’s High-Level Nuclear Waste. Cambridge, MA: MIT Press, 2006.

Riley, Peter D. Nuclear Waste: Law, Policy, and Pragmatism. Brookfield, VT: Ashgate Publishing, 2004.

United States Department of Energy, Office of Civilian Radioactive Waste Management. Final Environmental Impact Statement for a Geologic Repository for the Disposal of Spent Nuclear Fuel and High-Level Radioactive Waste at Yucca Mountain, Nye County, NevadaNorth Las Vegas, NV: U.S. Dept. of Energy, Office of Civilian Radioactive Waste Management, 2002.

United States Department of Energy, Office of Civilian Radioactive Waste Management. Program Plan, Revision 3. North Las Vegas, NV: U.S. Dept. of Energy, Office of Civilian Radioactive Waste Management, 2000.

United States Department of Energy, Office of Civilian Radioactive Waste Management. Site Characterization Progress Report, Yucca Mountain, Nevada. North Las Vegas, NV: U.S. Dept. of Energy, Office of Civilian Radioactive Waste Management, 2001.

OTHER

Civilian Radioactive Waste management.ψ<http://www.ymp.gov/>. United States Department of Energy, Office of Civilian Radioactive Waste Management (accessed November 16, 2006).

Nuclear Regulatory Commission.ψ<http://www.nrc.gov/> (accessed November 16, 2006).

State of Nevada. “Agency for Nuclear Projects.”ψ<http://www.state.nv.us/nucwaste/> (accessed November 16, 2006).

Yucca Mountain Standards.ψ<http://www.epa.gov/radiation/yucca/>. United States Environmental Protection Agency (accessed November 16, 2006).

Jennifer LeBlanc

Radioactive waste

Radioactive waste is generated during the production of electricity by nuclear power plants, by the eventual disposal of those facilities, and during the manufacturing and disposal of nuclear weapons and machines used in medical diagnosis and treatments, academic and industrial research, and certain industrial applications. Radioactive waste produces ionizing radiation , which can damage or destroy living tissues. Ionizing radiation transfers energy when it encounters biochemicals, causing them to become electrically charged, or ionized, which can damage their essential metabolic function.

Unlike conventionally toxic chemicals, the degree of danger from radioactive waste decreases over time. The half-life of a radioactive substance (or radioisotope) is the time required for one-half of an initial quantity to decay to other isotopes. Each radioisotope has a unique half-life, which can be only fractions of a second long, or as great as billions of years. The longer the half-life of a radioisotope, the longer is the period for which it must be safely stored or disposed until it is no longer hazardous.

Types of radioactive waste

Radioactive wastes are grouped into three categories: high-level waste, low-level waste, and transuranic waste. High-level waste emits intense levels of ionizing radiation for a relatively short time, and then emits lower levels for a much longer time. Most high-level waste is used nuclear fuel rods, which must be removed from the reactor core about every 2–4 years. Large quantities of high-level wastes are also associated with the production and disposal of nuclear weapons. In 2000, about 44,000 tons (40,000 tonnes) of spent fuel were stored at commercial nuclear power sites in the United States, a quantity expected to rise to 116,000 tons (105,000 tonnes) by 2035.

Low-level waste emits small amounts of ionizing radiation, usually for a long time, and it tends to be a high-volume waste. Low-level waste is produced from a variety of sources, such as filters and other cleaning material from nuclear plants, and used low-level radioisotopes from hospitals, universities, and industry. For example, in nuclear generating stations, tiny quantities of some radioactive materials may leak from the reactor. To protect the workers and the ambient environment, this radioactivity is removed with filters, which must periodically be replaced, becoming low-level waste.

Transuranic waste results primarily from the fabrication of plutonium as well as research activities at defense installations. Transuranics are elements, not found in nature, that are heavier than uranium . Most transuranics have special properties that increase the probability of causing damage to living tissue . Transuranic elements are found in both high-level and low-level radioactive waste. They can be separated from low-level waste, and are then treated as high-level waste.

Storage of radioactive waste

Storage can be defined as "a method of containment with a provision for retrieval." High-level and transuranic wastes are typically stored in on-site, deep-water storage ponds with thick, stainless steel-lined concrete walls. After about five years, the spent fuel has lost much of its radioactivity and can be moved into dry storage facilities. These are usually on-site, above-ground facilities in which the waste is stored in thick, concrete canisters.

Low-level waste is stored in concrete cylinders in shallow burial sites at nuclear plants or at designated waste sites. Since these wastes are not as much of a concern as high-level wastes, the regulations for their storage are not as strict. Basically, the waste must be covered and stored so that contact with ambient water is minimal.

Transportation of radioactive waste

The regulations for transporting radioactive waste are stringent due to the possibility of a transportation accident. Various containers are used for transporting specific kinds of waste. High-level waste has the most rigorous standards, and the containers in which it is shipped must be capable of withstanding tremendous pressure , impact, and heat , and are waterproof. There have been accidents in North America involving trucks and trains carrying radioactive waste, but no significant amount of radioactivity has ever been released to the environment as a result.

Treatment of radioactive waste

High-level radioactive waste can be treated by fuel reprocessing, which separates still-useful fuel isotopes from the rest of the waste. The useful isotopes can then be sent to a fabrication plant, which produces new nuclear fuel. Some technologists view this strategy as an excellent alternative to long-term storage, since it is essentially a re-use practice as opposed to disposal. Fuel reprocessing plants exist in Britain, France, Japan, Germany, India, and Russia. The United States, Canada, Spain, and Sweden do not have reprocessing plants, and are planning on long-term storage of their spent fuel.

Low-level radioactive waste is commonly a high-volume material, which can often be reduced prior to storage, transport, or disposal. It can be concentrated by filtering and removing the liquid portion, so only the solid residue remains for disposal. Alternatively, the material may be solidified by fusing it into glass or ceramic, which are highly stable materials.

Disposal of radioactive waste

Radioactive waste disposal refers to the long-term removal of the waste, and is designed to have minimal contact with organisms and the ambient environment. The safe disposal of high-level and transuranic wastes from nuclear power plants and nuclear weapons facilities has been the center of vigorous debate for more than 50 years, and researchers and policy-makers have yet to come up with politically acceptable solutions.

The most widely supported plan involves the burial of high-level waste deep underground in a stable geological formation. Less-popular ideas include burial under a stable glacier, or dumping into a deep oceanic trench. Part of the problem with any of these ideas is that disposal requires that the site will be secure for tens of thousands of years. This probably exceeds the time for which present governmental and social institutions will persist, so far-future generations may have to deal with the high-level nuclear wastes of the present ones. Moreover, nature can be a changeable, unpredictable, and powerful force , so there are unknown risks associated with all disposal options, and long-term, absolute guarantees cannot be given.

From 1940–1970, most low-level wastes were placed into steel drums and dumped into the ocean or into pits on land. However, there has been inevitable leakage from the drums, and environmentalists and the public objected to this method of disposal. Since 1970, the United States has been disposing its low-level waste at government-regulated disposal sites. In June 1990, the U. S. Nuclear Regulatory Commission (NRC) proposed that low-level radioactive waste be handled as regular garbage, due to its supposed low health risk. Epidemiologists calculated that implementing this policy might have caused 2,500 American deaths, but the NRC believed this risk was acceptable because it would save the nuclear power industry many millions of dollars every year. However, this proposal did not fully take account of recent research indicating that low-level radiation risks may be about 30 times higher than previously estimated.

Current problems in radioactive waste

The biggest technological challenge presently facing the nuclear industry is the long-term, safe disposal of high-level waste. The current preferred disposal option is to bury it deep underground. The Department of Energy proposed in 1983 that nine sites in geologically diverse locations be studied for suitability as one of two potential waste repositories. In 1987, Congress amended the Nuclear Waste Policy Act to redirect the Department of Energy to focus site characterization activities only at Yucca Mountain, Nevada. Huge sums of money have been spent in planning for this disposal option, but it remains controversial and is not yet built. The Department of Energy does predict, however, that the site will be available for disposal activities in the year 2010.

Political and scientific disagreements between the State of Nevada and the federal government have delayed the process, as have arguments presented by environmental groups. Opponents have complained that the site selection process has been dominated by political decision making rather than scientific reason. Technical concerns largely center on the geological stability of the area and the potential for water infiltration into the repository causing the release of radioactive material into the environment. Moreover, there are relatively young volcanoes nearby, several faults near the site, and the potential for climate change to cause ground-water levels to rise and inundate the repository horizon. Further complicating the issue is the fact that the proposed site lies adjacent to the Nevada Test Site (NTS), the location at which approximately one thousand nuclear weapons tests have been conducted. Some have argued that the extensive radioactive contamination associated with testing at the NTS makes the Yucca Mountain site more favorable for waste disposal. They suggest that the existing, uncontrolled contamination is unlikely to be significantly worsened by the proposed disposal of nuclear wastes in a controlled, engineered system and that localization of the wastes in a previously contaminated area is preferable to the contamination of a new site.

Despite the controversy, in February 2002, the Secretary of Energy recommended to the President that the Yucca Mountain site be selected as the nation's high-level nuclear waste repository. The President followed the Secretary's recommendation and approved the site, only to be vetoed by the Governor of the State of Nevada. However, the U.S. Congress voted to override the veto in July 2002. The State of Nevada has since filed lawsuits to stop the project and will very likely fight the licensing application with the NRC prior to the receipt of waste and operation of the repository. It seems that the only certainty is that the safe, long-term disposal of high-level radioactive wastes will continue to be an extreme challenge for technologists, and for society.

See also Nuclear reactor; Radiation.

Resources

books

Cohen, B. L. The Nuclear Energy Option: An Alternative for the 90s. New York: Plenum Press, 1990.

Keller, Edward. Environmental Geology. Upper Saddle River, NJ: Prentice-Hall, Inc., 2000.

Miller, G. T., Jr. Environmental Science: Sustaining the Earth. 3rd ed. Belmont, CA: Wadsworth Publishing Company, 1991.

Price, J. The Antinuclear Movement. rev. ed. Boston, MA: Twayne Publishers, 1990.

United States Department of Energy, Office of Civilian Radioactive Waste Management. Final Environmental Impact Statement for a Geologic Repository for the Disposal of Spent Nuclear Fuel and High-Level Radioactive Waste at Yucca Mountain, Nye County, Nevada North Las Vegas, NV: U.S. Dept. of Energy, Office of Civilian Radioactive Waste Management, 2002.

United States Department of Energy, Office of Civilian Radioactive Waste Management. Program Plan, Revision 3. North Las Vegas, NV: U.S. Dept. of Energy, Office of Civilian Radioactive Waste Management, 2000.

United States Department of Energy, Office of Civilian Radioactive Waste Management. Site Characterization Progress Report, Yucca Mountain, Nevada. North Las Vegas, NV: U.S. Dept. of Energy, Office of Civilian Radioactive Waste Management, 2001.

organizations

Nuclear Regulatory Commission [cited October 17, 2002] <http://www.nrc.gov/>.

State of Nevada Nuclear Water Project Office. [cited October 17, 2002) <http://www.state.nv.us/nucwaste/>.

other

The Yucca Mountain Project. United States Department of Energy, Office of Civilian Radioactive Waste Management [cited October 17, 2002]. <http://www.ymp.gov/>.

Yucca Mountain Standards. United States Environmental Protection Agency [cited October 17, 2002]. <http://www.epa.gov/radiation/yucca/>.

Jennifer LeBlanc

KEY TERMS

Half-life

—The time required for one-half of an initial quantity of a radioactive substance to disintegrate.

High-level waste

—Waste that emits intense levels of ionizing radiation for a short time, and then lower levels for a much longer time.

Ionizing radiation

—Radiation that can cause tissue damage or death.

Low-level waste

—Waste that emits small amounts of ionizing radiation, often for a long time.

Radioisotope

—A type of atom or isotope, such as strontium-90, that exhibits radioactivity.

Transuranic waste

—A special category of waste produced during the fabrication of plutonium as well as research activities at defense installations, involving non-natural elements heavier than uranium.

Radioactive Waste

Introduction

Radioactive waste, also called nuclear waste, is any unwanted material that contains a significant number of radioactive atoms. Such material is produced in large quantities by the facilities where nuclear power and nuclear weapons are made. Critics of nuclear power contend that nuclear waste cannot be reliably isolated from the environment for the many tens of thousands of years that must pass until its radioactivity declines to safe levels. They also argue that nuclear waste is dangerously attractive to terrorists and military opponents, who may seek to breach waste facilities and spread the material in inhabited areas using dirty bombs (chemical bombs packed with nuclear waste), hijacked aircraft, or other methods. Because of the long-lived nature of many radioactive materials, in large enough quantities they can render landscapes uninhabitable for decades or longer, causing long-term economic loss in addition to lingering effects such as higher mutation and cancer rates in plants and animals (including people).

Supporters of nuclear power say that radioactive waste can be processed to make it less dangerous and that it can be safely isolated from the environment by burying it in deep, dry rock formations.

Historical Background and Scientific Foundations

Radioactive atoms are atoms that, due to the structure of their nuclei, can break apart at any moment. When they do, they eject fast-moving subatomic particles and high-energy electromagnetic waves called gamma rays, closely akin to light rays. These particles and rays can harm living tissue. If they are intense, they can kill directly, while if they are weak, they can damage DNA and so increase the risk of cancer. Although the breakdown of any single atom of a radioactive substance cannot be predicted, each type (nuclide) of radioactive atom has an average lifespan. When large numbers of atoms are present, as is the case in radioactive waste, the behavior of that mass of atoms is predictable. For example, after a certain time, almost exactly half of the atoms will have changed into other nuclides. This time is termed the half-life of the nuclide. The half-lives of various nuclides vary from a fraction of a second to billions of years. The half-life of plutonium, a substance found in waste from nuclear reactors, is about 24,000 years. After about 10 half-lives, only one one-thousandth of any quantity of a radioactive nuclide will remain, so after 240,000 years any given amount of plutonium will only be about one one-thousandth as dangerous as it was originally. This period is often cited as the amount of time that nuclear waste containing plutonium must be isolated from the environment.

Nuclear waste did not begin to be generated in large quantities until after World War II (1939–1945), when several nations began building thousands of nuclear weapons along with scores of nuclear power plants to generate electricity. Because national survival was thought to depend on building atomic bombs, radioactive waste was treated as unimportant. As a result, poorly contained wastes were created by weapons programs. In 1954, a chemical explosion at a Soviet (now Russian) waste-storage site at Kyshtym in the southern Ural Mountains contaminated about 5,800 square mi (15,000 square km) and forced the evacuation of over 10,000 people. The Soviet Union denied that the event had occurred until 1989, and reports of hundreds of deaths from the accident are still denied by the Russian government.

In the United States, from the 1940s to the 1970s, much of its military nuclear waste was created, stored in underground tanks, or dumped into the environment at the Hanford Nuclear Reservation along the banks of the

WORDS TO KNOW

GAMMA RAYS: Streams of high-energy electromagnetic radiation given off by an atomic nucleus undergoing radioactive decay.

HALF LIFE: The amount of time it takes for half an initial amount to disintegrate.

NUCLIDE: A type of atom having a specific number of protons and neutrons in its nucleus.

RADIOACTIVITY: The property possessed by some elements of spontaneously emitting energy in the form of particles or waves by disintegration of their atomic nuclei.

Columbia River in Washington. Scores of millions of gallons of highly radioactive waste were pumped into leaky tanks or poured into open ditches: An amount of radioactivity was released each day into the Columbia River that would now be considered a major nuclear accident. Radioactive nuclides are still moving through groundwater under the Hanford site, gradually entering the river. A number of these nuclides can concentrate in human tissues and cause cancer. The government did not release this information until the 1980s, when information about the waste leaks was obtained by journalists and environmentalists under the Freedom of Information Act.

Nuclear waste from power plants has been better contained. The primary form of waste from nuclear reactors is spent fuel, that is, metal rods containing pellets of radioactive metal whose mixture of nuclides is no longer suitable for generating power. These spent fuel rods, after removal from the reactor core, are first immersed in boric acid in steel-lined concrete pools. Later, when they are cooler (because some of its shorter-lived nuclides have decayed into other nuclides), they are moved into heavy steel canisters and stored near the nuclear power plant. Such facilities are not intended to contain the waste permanently. The nuclear industry and government agencies envision two possible futures for such waste: (1) It may be reprocessed to extract its plutonium, which can then be burned as a nuclear fuel. This plan must overcome the obstacle that reprocessing produces larger volumes of high-level radioactive waste than it begins with, though they contain less plutonium. (2) It may be buried in deep, dry-rock formations, where it will hopefully remain until its radioactivity has declined to safe lev

Impacts and Issues

As of 2008, radioactive waste was not yet being stored in any deep-rock permanent facilities anywhere in the world, although it seemed likely that a Finnish facility would begin accepting waste in 2020. In the United States, plans for deep disposal of nuclear waste from

IN CONTEXT: COUSTEAU’S CRUSADE AGAINST RADIOACTIVE WASTE

Jacques-Yves Cousteau (1910–1997) was one of the most famous ocean explorers of the twentieth century. He authored more than fifty books and encyclopedias about the oceans, produced numerous films and television shows featuring his adventures at sea, and founded a society for the protection of the oceans. He was a member of the National Academy of Sciences in the United States and was awarded the United Nations International Environmental Prize in 1977.

Cousteau’s voyages on his ship Calypso enchanted the public and exposed people to the beauty and fragility of many different, and often inaccessible, environments. He was able to demonstrate the threats that pollution and overexploitation posed through his dramatic images and descriptive prose. His writing, in which scientific concepts are explained in a compelling manner similar to storytelling, is a major part of his legacy, as it increased the public’s awareness of the great beauty and diversity found in environments throughout the world.

Cousteau’s success in film and writing made him a major spokesperson in the environmental movement of the late twentieth century.

Cousteau chose several environmental problems on which he focused his attention and the attention of the public. This often resulted in important changes to government policy. In 1960, Cousteau became concerned about the environmental effects of dumping radioactive waste in the Mediterranean Sea by the European Atomic Energy Community. He launched a publicity campaign pressuring governments to stop the practice. Eventually, dumping radioactive waste into the Mediterranean was banned.

more than 100 reactors around the country remain stalled. The Yucca Mountain facility was originally meant to begin receiving waste in 1998, but as of 2008, government officials said it would be at least 2017, probably later, before this could occur. The state government of Nevada strenuously opposes storage of radioactive waste at the site, and scientific concerns about the site’s geological integrity have been raised. Meanwhile, by early 2008, owners of U.S. nuclear power plants had filed 60 lawsuits against the federal government to recover costs due to delays in opening Yucca Mountain (temporary waste-storage sites are expensive for plant owners.) Government payments to industry are forecast to run from $7 billion to $35 billion or more.

See Also Nuclear Power

BIBLIOGRAPHY

Books

McFarlane, Allison, and Rodney C. Ewing, eds.Uncertainty Underground: Yucca Mountain and the Nation’s High-Level Nuclear Waste. Cambridge, MA: MIT Press, 2006.

Periodicals

Kanter, James. “Radioactive Nimby: No One Wants Nuclear Waste.” New York Times (November 7, 2007).

Wald, Matthew L. “Agency Is Seen as Unfazed on Atom Waste.” New York Times (June 12, 2004).

Wald, Matthew L. “As Nuclear Waste Languishes,Expense to U.S. Rises.” New York Times (February 17,2008).

Web Sites

National Academy of Sciences. “Health Effects of Exposure to Low-Level Ionizing Radiation: BEIR V.” http://www.nap.edu/openbook.php?isbn=0309039959 (accessed April 16, 2008).

Sierra Club. “Nuclear Waste.” http://www.sierraclub.org/nuclearwaste/nucw.asp (accessed April 16, 2008).

U.S. Department of Energy. “Yucca Mountain Repository.” http://www.ocrwm.doe.gov/ym_repository/index.shtml#skiptop (accessed April 16, 2008).

Larry Gilman

Radioactive waste

Radioactive waste is the "garbage" left as a result of the use of nuclear materials by human societies. Such waste can be categorized as low-level, intermediate-level, or high-level waste. The term transuranic waste is also used to describe materials consisting of elements heavier than uranium in the periodic table.

The term low-level radioactive waste usually refers to materials that contain a small amount of radioactivity dispersed in a large volume of material. Such materials are produced in a great variety of industrial, medical, and research procedures. A common practice is to store these materials in sealed containers until their level of radioactivity is very low and then to dispose of them by shallow burial or in other traditional solid waste disposal systems.

The assumption is that the level of radiation released by these wastes is too low to cause any harmful environmental effects. That assumption has been challenged by some scientists who believe that enough is not yet known about the long-term effects of radiation. They suggest that safer methods of disposal for such wastes need to be developed.

Intermediate-level wastes, as the name suggests, contain a higher level of radioactivity than low-level wastes, but a lower level than high-level wastes. These materials cannot be discharged directly into the environment . An important source of such wastes is the re-processing of nuclear fuels. At one time, large quantities of intermediate-level wastes were dumped into the deepest parts of the Atlantic Ocean. That practice has been discontinued and intermediate-level wastes are now being stored on land until a permanent disposal system is developed.

High-level radioactive wastes consist of materials that contain a large amount of radioactivity that will remain at dangerous levels for hundreds or even thousands of years. These materials pose the most difficult disposal problem of all since they must be completely isolated and stored for very long periods of time. The primary sources of high-level wastes are nuclear power plants and research and development of nuclear weapons .

A number of methods for the storage of high-level wastes have been suggested. Among these are burial in large chunks of concrete, encapsulation in glass or ceramic, projection of them inside rockets into outer space, and burial in the Antarctic ice sheet. Various countries around the world have developed a variety of methods for storing their high-level wastes. In Canada, such wastes have been stored in water-filled pools for more than 25 years. France, with one of the world's largest nuclear power establishments, has developed no permanent storage system but plans to build a large underground vault for its wastes by the early twenty-first century.

In the United States, Congress passed the Nuclear Waste Policy Act in 1982, outlining a complete program for the construction of a high-level waste repository in the early twenty-first century. In 1987, Yucca Mountain , Nevada, was selected as the location for that site. Current plans call for a huge vault 1,000 ft (305 m) underground as the site for long-term, high-level waste storage at this location.

See also Nuclear fission; Nuclear Regulatory Commission (NRC); Ocean dumping; Office of Civilian Radioactive Waste Management (OCRWM); Radioactive decay; Radioactive waste management

[David E. Newton ]

RESOURCES

BOOKS

Bartlett, D. L., and J. B. Steele. Forevermore: Nuclear Waste in America. New York: W. W. Norton, 1985.

Carter, L. J. Nuclear Imperatives and Public Trust: Dealing With Radioactive Waste. Baltimore: Resources for the Future, 1987.

League of Women Voters. The Nuclear Waste Primer. Washington, DC: League of Women Voters, 1985.

Managing the Nation's Nuclear Waste. Washington, DC: Office of Civilian Radioactive Waste Management, March 1990.

Resnikoff, M. Deadly Defense: Military Radioactive Landfills. New York: Radioactive Waste Campaign, 1988.

PERIODICALS

Hunt, C. B. "Disposal of Radioactive Wastes." Bulletin of the Atomic Scientists (April 1984): 44–46.