nuclear power

1. Power, especially electricity, the source of which is nuclear fission or fusion.
2. A nation or group possessing nuclear weapons.

Power derived from fission or fusion nuclear reactions. More conventionally, nuclear power is interpreted as the utilization of the fission reactions in a nuclear power reactor to produce steam for electric power production, for ship propulsion, or for process heat. Fission reactions involve the breakup of the nucleus of high-mass atoms and yield an energy release which is more than a millionfold greater than that obtained from chemical reactions involving the burning of a fuel. Successful control of the nuclear fission reactions utilizes this intensive source of energy. See also Nuclear fission.

Fission reactions provide intensive sources of energy. For example, the fissioning of an atom of uranium yields about 200 MeV, whereas the oxidation of an atom of carbon releases only 4 eV. On a weight basis, this 50 × 10⁶ energy ratio becomes about 2.5 × 10⁶. Uranium consists of several isotopes, only 0.7% of which is uranium-235, the fissile fuel currently used in reactors. Even with these considerations, including the need to enrich the fuel to several percent uranium-235, the fission reactions are attractive energy sources when coupled with abundant and relatively cheap uranium ore.

Although the main process of nuclear power is the release of energy in the fission process which occurs in the reactor, there are a number of other important processes, such as mining and waste disposal, which both precede and follow fission. Together they constitute the nuclear fuel cycle. See also Nuclear fuel cycle.

Power reactors include light-water-moderated and -cooled reactors (LWRs), including the pressurized-water reactor (PWR) and the boiling-water reactor (BWR). The high-temperature gas-cooled reactor (HTGR), and the liquid-metal-cooled fast breeder reactor (LMFBR) have reached a high level of development but are not used for commercial purposes. See also Nuclear reactor.

Critics of nuclear power consider the radioactive wastes generated by the nuclear industry to be too great a burden for society to bear. They argue that since the high-level wastes will contain highly toxic materials with long half-lives, such as a few tenths of one percent of plutonium that was in the irradiated fuel, the safekeeping of these materials must be assured for time periods longer than social orders have existed in the past. Nuclear proponents answer that the time required for isolation is much shorter, since only 500 to 1000 years is needed before the hazard posed by nuclear waste falls below that posed by common natural ore deposits in the environment. See also Radioactive waste management.

Nuclear power facilities present a potential hazard rarely encounted with other facilities; that is, radiation. A major health hazard would result if, for instance, a significant fraction of the core inventory of a power reactor were released to the atmosphere. Such a release of radioactivity is clearly unacceptable, and steps are taken to assure it could never happen. These include use of engineered safety systems, various construction and design codes, regulations on reactor operation, and periodic maintenance and inspection.

Electrical power generated by a nuclear reactor.

The use of nuclear power to generate electricity began in the late 1950s. At the close of the twentieth century, nuclear power was supplying about 20 percent of the electricity generated in the United States and about 16 percent worldwide.

Nuclear power has been the most controversial of all energy sources. Public concerns about reactor safety and environmental issues were especially heightened by the 1979 accident at Three Mile Island in Pennsylvania and the much more serious accident in 1986 at Chernobyl in Ukraine. Construction of new nuclear power plants has slowed considerably since then, and some industrialized countries may abandon this energy source. Concerns about disposal of spent nuclear fuel have also affected public confidence in nuclear power. Although many scientists believe that spent fuel and other highly radioactive wastes can be disposed of safely in a geologic repository located far below ground, disposal sites for these wastes have not been approved, and the need to store spent fuel until disposal facilities are available raises safety and environmental concerns. The public also has not supported development of new disposal facilities for low-level radioactive wastes generated at nuclear power plants and in many other commercial activities. Other factors contributing to public concerns have included environmental problems at sites operated under nuclear weapons programs and fears that plutonium produced at nuclear power plants could be diverted for use in nuclear weapons.

Public concerns about safety and environmental issues have been exacerbated by financial risks in the nuclear power industry, including the high cost of constructing and operating nuclear power plants, potentially high costs of decommissioning nuclear facilities, and costs for storage and disposal of spent fuel and other nuclear wastes. Nuclear power may not remain competitive with other energy sources unless these costs are reduced.

Proponents of nuclear power emphasize its significant benefits. Past accidents notwithstanding, the nuclear power industry has an enviable safety record in those industrialized countries that require extensive reactor safety systems. Uranium used in nuclear fuel is abundant, which reduces dependence on foreign energy supplies and preserves oil and natural gas for essential uses. Nuclear reactors produce the greatest amount of energy per amount of fuel of any nonrenewable energy source, and the environmental damage from use of nuclear power is less than with other major energy sources, especially coal. Perhaps most importantly, the use of nuclear power in place of coal, oil, and natural gas greatly reduces emissions of carbon dioxide, which is believed to be a factor in global warming, and other hazardous air pollutants.

Given these benefits, many energy experts believe that nuclear power is an important energy source for the future. A major challenge will be to address public concerns about safety and environmental issues. The keys to meeting this challenge may include resolving concerns about nuclear waste disposal, siting of new reactors in remote areas, developing smaller reactors that incorporate passive safety systems, and using standard power plant designs to lower construction and operating costs.

(SEE ALSO: Chernobyl; Energy; Not In My Backyard [NIMBY]; Nuclear Waste; Risk Assessment, Risk Management; Three Mile Island)

Bibliography

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

Gofman, J. W., and Tamplin, A. R. (1971). Poisoned Power: The Case Against Nuclear Power Plants. Emmaus, PA: Rodale Press.

Jungk, R. (1979). The New Tyranny: How Nuclear Power Enslaves Us. New York: Grosset & Dunlap, Inc.

Rhodes, R. (1993). Nuclear Renewal: Common Sense about Energy. New York: Whittle Books.

— DAVID C. KOCHER

1. a country that has nuclear weapons.

2. electric or motive power generated by a nuclear reactor.

nuclear-powered adj.

See the Introduction, Abbreviations and Pronunciation for further details.

A form of energy which uses nuclear reactions to produce steam to turn generators. Naturally occurring uranium is concentrated, enriched, and converted to uranium dioxide—the fuel used in the reactor. This fuel readily undergoes nuclear fission which produces large amounts of heat. Some of the highly radioactive spent fuel may be reprocessed while the bulk must be disposed of. Both are costly and hazardous undertakings. The main advantage of nuclear power is the relatively small amount of an abundant fuel which is required. The major disadvantages are very high construction and decommissioning costs, highly technical operations, the problem of waste disposal, and the major problems which may arise with any accident, such as the Chernobyl disaster of April 1986. Furthermore, nuclear power stations have a short lifespan.

The locational requirements of a nuclear power station include very large amounts of water as a coolant, stable and firm geological conditions, and distance from large centres of population because of the radiation hazard. In 1990, 33.5% of Western Europe's electricity was produced from nuclear power stations, major producers being Belgium (61% of total electricity generated), and France (74.5%). The UK figure was 21.7%.

For more information on nuclear power, visit Britannica.com.

Nuclear Power refers to the energy produced by fission, when atoms are split, or by fusion, when two nuclei of a light atomare fused to forma single nucleus. The energy produced can be used for weapons or for peaceful purposes. The phrase is also used to designate those nations that have Nuclear Weapons. The first five nations to declare that they had nuclear weapons were the United States (1945), the former Soviet Union (1949), Great Britain (1952), France (1960), and China (1964), known as the "Big Five." The breakup of the Soviet Union in the early 1990s resulted in the addition of Belarus, Kazakhstan, and Ukraine as nuclear-weapon states because the nuclear missiles and storage sites placed on their territory by the Soviet Union became the property of these newly independent states; all three, however, transferred their weapons to Russia. India conducted its first nuclear test in 1974, followed by Pakistan in 1998. North Korea is believed to have the capacity to develop nuclear weapons within a short time. Others, such as Israel, have likely developed one or more such weapons secretly. Some analysts believe that another group of countries, including Iraq, were trying to develop nuclear weapons at the turn of the twenty-first century.

Nuclear power also refers to plants and industry that generate electric power from nuclear sources. The possibility of using the energy in the atomic nucleus as a power source was widely recognized soon after the discovery of nuclear fission late in 1938, but only the United States was able to devote any significant effort to atomic energy development during World War II. On 2 December 1942 Enrico Fermi and others achieved the first self-sustained chain reaction at Stagg Field at the University of Chicago. This experiment made possible the construction of three large plutonium-producing reactors; each generated about 250,000 kilowatts of energy, but they were not used for electric power production.

Despite the initial popular belief that the use of nuclear power was imminent, technical progress was slow after the war. The U.S. Atomic Energy Commission (AEC), facing extreme shortages of uranium ore, supported only three small reactor projects before 1950. One of these, the Experimental Breeder Reactor No. 1, succeeded in generating a few kilowatts of electric power late in 1951, an accomplishment more symbolic than practical.

Growing industrial interest in nuclear power by 1952, basic revision in atomic energy legislation in 1954, and increasing ore supplies made a more ambitious program possible in the 1950s. The AEC adopted a five-year plan designed to test the feasibility of five different reactor systems. One of these, the pressurized water reactor (PWR)—designed and and built by a joint AEC-Navy tea munder Rear Adm. H. G. Rickover, at Shippingport, Pennsylvania—produced 60,000 kilowatts of electricity for commercial use before the end of 1957. The AEC's Argonne National Laboratory, at Lemont, Illinois, under Walter H. Zinn, successfully developed the experimental boiling water reactor (EBWR). The PWR and EBWR committed the United States almost exclusively to water-cooled reactors for the next two decades. By the end of 1957, the AEC had seven experimental reactors in operation, and American industry had started nine independent or cooperative projects expected to produce 800,000 kilowatts of electricity by the mid-1960s.

Nuclear power plants differ from hydroelectric plants—which generate electricity from the force of flowing water—and from coal-, oil-, or gas-fired electric plants, which generate electricity from the heat drawn from burning fossil fuels. Nuclear power plants generate steam to drive electric turbines by circulating liquid through a nuclear reactor. The reactor produces heat through the controlled fission of atomic fuel. Normally the fuel for power reactors is slightly enriched uranium. These differences give nuclear reactors several advantages over power generation using other fuels. Unlike fossil fuels, nuclear fuel does not foul the air and is not dependent on oil imports from unstable parts of the world. Before the environmental effects of radioactive wastes and the safety hazards of nuclear plants became apparent in the 1960s and 1970s, some environmentalists were strong advocates of nuclear power as a "clean" energy source. Others, aware of the rising costs of the world's diminishing coal, oil, and natural gas resources and the limitation on the number of hydroelectric power plants that could be built, believed that nuclear plants could be the key to an independent American energy supply.

The attraction of electricity generated by nuclear power was not limited to the United States. In contrast to the American emphasis on water-cooled reactors, both the United Kingdom and France chose to rely on gas-cooled systems. By 1957 the United Kingdom was building or planning twelve reactors with a capacity of more than 1 million kilowatts; the French were building five reactors totaling more than 350,000 kilowatts. The Soviet Union was planning a 200,000-kilowatt PWR and two smaller boiling-water reactors. By 1966 nuclear power generators were being built or operating in five countries. By 1980 there were a hundred nuclear power plants in the United States.

Technical difficulties prevented any of these national plans from being realized by the early 1960s. In the United States the AEC countered the resulting pessimism by predicting the imminence of economically competitive nuclear power and concentrating resources on the most promising reactor designs—water-cooled reactors for the immediate future and sodium-cooled breeder reactors for later decades in the century. This confidence was fulfilled by early 1964, when an American power company first announced its decision, on the basis of economics alone, to construct a nuclear power plant. Despite a temporary dampening effect of licensing delays and challenges from environmentalists protesting the dumping of radioactive wastes, the trend toward nuclear power accelerated again in the early 1970s. By the fall of 1972, the total nuclear gross generating capacity of all nations outside the Communist bloc had reached 32 million kilowatts. Of this total, the United States provided 13 million electrical kilowatts generated in twenty-eight operating plants. More than a hundred additional plants with a total capacity of more than 116 million kilowatts had been ordered or were under construction in the United States.

A serious accident at Three Mile Island in 1979 proved to be a major turning point for nuclear power in the United States, and no new nuclear generators have been ordered since. All of the increases in nuclear-generated electricity since 1979 have come from existing plants, which have boosted their national capacity factor from under 65 percent in 1970 to 76 percent in 1996.

One of the byproducts of nuclear-power generation is plutonium, a material that can be chemically processed for use in nuclear weapons. The danger of such use by nonnuclear nations led to international safeguards under the 1968 Nuclear Nonproliferation Treaty. In Article III signatory nations agreed to inspections by the International Atomic Energy Agency (IAEA), "with a view to preventing diversion of nuclear energy from peaceful uses to nuclear weapons or other nuclear explosive devices." Most of the world's nuclear and nonnuclear nations signed this treaty. Iraq in 1992 and North Korea in 1994 were subjected to IAEA inspections that proved treaty violations in the former and raised serious suspicions about the latter. Both nations were signatories of the treaty, although North Korea announced its withdrawal some months prior to inspection. Iraq's nuclear-weapon production facilities were discovered as a result of a series of highly intrusive IAEA inspections and were subsequently destroyed by the United Nations.

When Congress passed the Atomic Energy Act of 1954, it approved President Dwight D. Eisenhower's Atoms for Peace program, which included commercial development of nuclear reactors for the purpose of generating electric power. During the 1960s electricity generated by nuclear power contributed 1 to 2 percent of the nation's energy total. Since then that percentage has grown steadily, surpassing the proportion from hydroelectric sources in 1984.By 1990 nuclear power amounted to one-fifth of the nation's total generation of electricity. By 1992 nuclear generation reached 619 billion net kilowatt hours, more than double the amount generated in 1979, the year of the Three Mile Island accident.

In reaction to the 1973 oil embargo, U.S. consumers temporarily used less energy, which diminished the rate of growth in electricity generation. As a result of this and other factors, such as higher construction costs, delays brought on by antinuclear protests, increased operating costs resulting from new federal regulations, and uncertainties about disposal of high-level radioactive waste, no requests for construction of new nuclear power plants have been received by the Nuclear Regulatory Commission since 1978.The level of generation was still rising, however, because plants started in the 1970s had gone on-line, and modernization after 1979 made power plants more efficient. The rising production trend continued until the end of the twentieth century; in the year 2000, for example, 104 commercial nuclear plants in the United States produced 20.5 percent of all electricity consumed in the United States. Nuclear power's future is far from clear, however. The Energy Information Administration projected in 2001 that 27 percent of the nation's nuclear generating capacity then in existence would be retired by 2020, with no construction of new plants anticipated.

Bibliography

Department of Energy, Energy Information Administration. Annual Energy Outlook 2002 with Projections to 2020. Washington, D.C.: Department of Energy, 2001.

Deudney, Daniel, and Christopher Flavin. Renewable Energy: The Power to Choose. New York: W.W. Norton, 1983.

Duffy, Robert J. Nuclear Politics in America: A History and Theory of Government Regulation. Lawrence: University Press of Kansas, 1997.

Henderson, Harry. Nuclear Power: A Reference Handbook. Santa Barbara, Calif.: ABC-CLIO, 2000.

A form of energy produced by an atomic reaction, capable of producing an alternative source of electrical power to that supplied by coal, gas, or oil.

The dropping of the atom bomb on Hiroshima, Japan, by the United States in 1945 initiated the atomic age. Nuclear energy immediately became a military weapon of terrifying magnitude. For the physicists who worked on the atom bomb, the promise of nuclear energy was not solely military. They envisioned nuclear power as a safe, clean, cheap, and abundant source of energy that would end society's dependence on fossil fuels. At the end of World War II, leaders called for the peaceful use of nuclear energy.

Congress passed the Atomic Energy Act of 1946 (42 U.S.C.A. § 2011 et seq.), which shifted nuclear development from military to civilian government control. Very little development of commercial nuclear power occurred from 1946 to 1954 because the 1946 law maintained a federal government monopoly over the control, use, and ownership of nuclear reactors and fuels.

Congress amended the Atomic Energy Act in 1954 (68 Stat. 919) to encourage the private commercial development of nuclear power. The act ended the federal government's monopoly over nonmilitary uses of nuclear energy and allowed private ownership of reactors under licensing procedures established by the Atomic Energy Commission (AEC). Private power companies did not rush to build nuclear power plants because they feared the financial consequences of a nuclear accident. Congress responded by passing the Price-Anderson Act of 1957 (42 U.S.C.A. § 2210), which limited the liability of the nuclear power industry and assured compensation for the public. With the passage of the Price-Anderson Act, power companies began to build nuclear plants. By the 1990s approximately 110 nuclear plants were operating in the United States, supplying 20 percent of the nation's electricity.

A nuclear reactor produces energy through a chain reaction that splits a uranium nucleus, releasing energy in the form of heat. Fast breeder reactors, which use plutonium as fuel, generate more energy than they expend. Plutonium is not a natural element. It must be recycled from the excess uranium produced from a chain reaction. The radioactivity of plutonium is higher and its life is longer than that of any other element. Because of these characteristics, the public has been concerned about the safety of its development and use.

Nuclear power plants were built in the United States largely because the demand for electricity grew at a steady rate in the 1960s and coal-burning facilities were an environmentally unattractive alternative. The high price of oil during the mid-1970s continued to make nuclear power economically desirable and helped keep nuclear energy a prominent part of national energy plans.

Until 1969 the AEC did not have a formal process for evaluating the environmental impact of building nuclear power plants. In that year Congress passed the National Environmental Policy Act of 1969 (42 U.S.C.A. §§ 4321-4370), which required environmental impact statements for all major federal activities. In the 1970s the temper of nuclear regulation changed. People were no longer complacent about nuclear power safety or convinced by environmental claims made by industry and government.

This lack of public trust centered on the role of the AEC as both a promoter of nuclear technology and a regulator of the nuclear power industry. In 1974, realizing the cross purposes of promotion and safety, Congress passed the Energy Reorganization Act (42 U.S.C.A. §§ 5801-5879), which created two agencies with different missions. The Nuclear Regulatory Commission (NRC) is an independent agency responsible for safety and licensing. The Energy Research and Development Administration (ERDA), later absorbed into the Department of Energy, is responsible for promotion and development of nuclear power. This alignment did not completely remove fundamental regulatory conflict for the NRC, because the agency is responsible both for licensing plants and for safety oversight. If the NRC is too vigorous in exercising its safety role, the resulting compliance costs act as a disincentive to invest in nuclear plants.

A nuclear facility cannot be built without a construction permit issued by the NRC. An environmental impact statement that assesses the effect the facility will have on the environment must also be filed with the Environmental Protection Agency (EPA). Once built, a nuclear plant must operate pursuant to a license from the NRC. A license requires that the facility use the lowest levels of radiation necessary to reasonably and efficiently maintain operations. The NRC also issues licenses for the use of nuclear materials, for transportation of nuclear materials, and for the export and import of nuclear materials, facilities, and components.

Nuclear power regulation is highly centralized in the federal government when nuclear safety and radiological hazards are at issue. States may address the financial capability of power companies to dispose of waste and may define state tort liability for injuries suffered at nuclear facilities.

Public confidence in the nuclear power industry suffered a major blow in 1979 when an accident occurred at the Three Mile Island Nuclear Station near Harrisburg, Pennsylvania. No one was hurt during the accident although radioactive gases did escape through the plant's ventilating system. The accident did reveal, however, the nuclear power industry's lack of emergency preparedness.

Following the incident at Three Mile Island, the NRC increased safety inspections, stepped up enforcement, required the retrofitting of systems to enhance safety, and developed emergency preparedness rules. These regulations delayed the opening of new nuclear plants during the early 1980s.

Nuclear power became less attractive to energy companies in the 1980s. The problem of disposing of nuclear waste became the focal point for the industry. Congress passed the Nuclear Waste Policy Act of 1982 (42 U.S.C.A. §§ 10101-10226), which directed the Department of Energy to formally begin planning the disposal of nuclear wastes and imposed most of the costs of disposal on the industry. The escalating costs of waste disposal helped bring construction of new nuclear facilities to a stop.

The problem of what to do with nuclear waste has proved to be difficult to solve. Nuclear material is contained in fuel rods. When spent fuel rods and other waste products fill the storage capacity at utility plants, the plants must either expand their storage capacity or find permanent off-site storage. Developing permanent nuclear waste sites is imperative because nuclear waste continues to accumulate. In addition, more than one hundred of the nuclear power facilities must be permanently shut down between 2010 and 2025 because their equipment and infrastructure will no longer be safe. This will entail removing most radioactive elements within each plant's nuclear reactor and then razing the entire plant.

The federal government has encountered political controversy and public opposition when it has sought to identify potential permanent nuclear waste sites. Since 1986 it has been unsuccessful in finding an acceptable site. Yucca Mountain, Nevada, is the only place earmarked for a site study. Once a site is selected, opponents of the selection will likely challenge it in court, delaying the process even further.

The commercial prospects for nuclear energy have faded. The decommissioning of nuclear plants in the early twenty-first century will be a huge undertaking. The cost, per plant, will be more than one billion dollars. Utility customers will pay for the costs in higher utility rates, but power companies will have to devote significant amounts of time, energy, and money to complete the process.

Public confidence in the safety of nuclear energy has declined as well. The 1986 explosion of a nuclear reactor at Chernobyl in the Ukraine was devastating. Radiation fifty times higher than that at Three Mile Island exposed people nearest the reactor, and a cloud of radioactive fallout spread to Western Europe, causing the deaths of more than thirty people.

See: Energy Department; Environmental Law; Public Utilities; Solid Wastes, Hazardous Substances, and Toxic Pollutants.

After World War II, governments instituted a search for peaceful uses for nuclear energy. Comic books on "the atom" informed children that the atomic energy in a steamship ticket is enough to circle the globe hundreds of times, raising the expectations of a generation. Scientists designed nuclear reactors that some expected would become sources of unlimited power.

According to Lewis Strauss, chairman of the Atomic Energy Commission (AEC) in 1954, electricity from nuclear power would be "too cheap to meter."

The initial use of nuclear reactors was not peaceful, however. The first energy-producing reactors powered nuclear submarines, first launched by the United States in January 1954.

The Soviet Union completed in June 1954 a small reactor that delivered the first peaceful application of nuclear energy, but not in practical amounts. In the United States, experimental and submarine reactors were connected to the electric power grid in June 1955. In England a 50,000-kilowatt reactor, known as Calder Hall, started operation in October 1956.

Since then, nuclear reactors have been built in many countries. In some, such as Japan and France, nuclear power is now the main source of energy. This development made these countries independent from the use of imported oil, supplies of which can be disturbed by political crises.

Enthusiasts have heralded nuclear energy as ecologically sound because it does not produce carbon dioxide that causes global warming. However, the partial meltdown of a nuclear reactor at the Three Mile Island power plant near Harrisburg, Pennsylvania, in 1979 and the reactor explosion in Chernobyl (Ukraine) in 1986 showed that nuclear energy carries with it the potential for disaster. A second problem is cost; despite Strauss's prediction, nuclear energy is more expensive to generate than energy from fossil fuel. A third major problem is disposal of radioactive waste fuel, some parts of which remain dangerously radioactive for thousands of years.

During the 1970s, engineers began to design nuclear reactors to incorporate passive safety systems. Such systems use cooling methods that rely on gravity alone and do not require pumps that can break down. In one design, reactor vessels would be submerged in tanks of boron-laced water that would flood the reactor immediately in the case of a problem, stopping the nuclear reactions. But in the United States, at least, such designs have not been carried out. Only two new power plants have been built in the United States since 1990, partly as a result of concern for their safety, but also for economic reasons. Despite this, the United States remains the leader both in number of operating reactors and power generated.

A new concern surfaced after September 11, 2001, when it became apparent that terrorists commandeering airplanes might crash into a nuclear power plant or might try to damage such a plant with conventional explosives. Even surface dumps for nuclear waste could damage a wide region around them if struck with a large bomb. Calls for shutting down plants near heavily populated regions increased.