Background (Encyclopedia of Global Resources)
The fission reaction that occurs in a nuclear reactor releases tremendous amounts of energy in the form of heat. This heat can be used to produce steam, and the steam can be used to drive an electric generator. It appears that uranium, the fuel for nuclear reactors, will far outlast oil and coal as a source of energy. However, concerns about the safety of nuclear reactors and about the disposal of used fuel and other wastes have slowed the pace of reactor development dramatically. In addition, nuclear power plants are usually more expensive to construct than coal- or gas-fired plants.
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Scientific Principles and Historical Background (Encyclopedia of Global Resources)
Naturally occurring uranium consists of 99.3 percent uranium 238 and 0.7 percent uranium 235. The nuclei of both of these isotopes contain 92 protons. Uranium-238 nuclei also contain 146 neutrons, while uranium-235 nuclei contain 143 neutrons. When a neutron strikes the nucleus of a uranium-235 atom, the nucleus splits roughly in half. Several neutrons and considerable heat are released. This process is called fission. The neutrons that are released can cause the fission of other uranium-235 nuclei, so the process continues in a chain reaction. The smaller nuclei that result from fission are called fission products. They are highly radioactive, and this radioactivity is accompanied by significant heat generation. When 1 gram of uranium fissions, it releases the same amount of heat as burning about 3 metric tons of coal or more than 12 barrels of oil.
In 1934, Enrico Fermi, working in Rome, was bombarding uranium atoms with neutrons. He expected the neutrons to be absorbed and new, heavier atoms to result. However, the chemical properties of the atoms he produced were not what he expected. Lise Meitner, Irène Joliot-Curie (the daughter of Nobel Prize winner Marie Curie), and Otto Hahn reproduced Fermi’s experiments. They too were baffled by the results. Finally, Hahn realized what was happening: Instead of being absorbed into the uranium-235 nucleus, the neutrons were causing that nucleus to...
(The entire section is 636 words.)
Nuclear Reactor Design (Encyclopedia of Global Resources)
The electric generators and the steam turbines at a nuclear plant are similar to those at a coal-, oil-, or natural gas-fired plants. The difference lies in how the steam that drives the turbine is produced. Nuclear reactor fuel consists of uranium or plutonium oxide pellets contained inside zirconium tubes called fuel rods. These rods are arranged in a grid pattern, with space between them for coolant to flow. This part of a nuclear reactor is called the core. Movable control rods of neutron-absorbing material such as cadmium are used to regulate the fission rate in the reactor. The reactor core is housed in a strong steel container called the pressure vessel. Coolant flows into the pressure vessel, from which it flows through the core and absorbs the heat produced by fission. Then the heated coolant flows out of the pressure vessel and into other parts of the system. This heat is used to make steam. The cooling fluid can be a gas such as air or carbon dioxide, a liquid such as water, or a molten metal such as sodium. Nearly all electric power reactors in the United States are water cooled. There are two basic designs: pressurized-water reactors and boiling-water reactors.
In a pressurized-water reactor, water at very high pressure passes through the reactor core, the place where the uranium fuel is located. This water, which is called the primary water, absorbs the heat released by fission but does not boil because...
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Fusion (Encyclopedia of Global Resources)
Fusion is an entirely different process from fission. Fission is the splitting apart of the nucleus of a uranium or plutonium atom. Fusion is the joining of two light atoms to form a heavier one. For instance, two hydrogen atoms can fuse to form a helium atom. The fusion reaction is also accompanied by the release of large amounts of heat. In fact it is the fusion reaction that generates the tremendous heat that stars give off. The potential of fusion to drive nuclear reactors is being explored, but there are significant problems involved.
An ordinary hydrogen atom has a nucleus composed of a lone proton, but there are two other forms of hydrogen. Different forms of the same element are called isotopes, and the isotopes of hydrogen are called deuterium and tritium. A deuterium nucleus contains a proton and a neutron, while a tritium nucleus contains a proton and two neutrons. Deuterium occurs naturally. Some of the hydrogen atoms in natural water molecules are actually deuterium. The deuterium in a cup of coffee could produce enough energy through fusion to drive a car for about a week of normal driving.
Fusion, like fission, was first used in weapons of war. In a hydrogen bomb one deuterium nucleus and one tritium nucleus fuse to make a helium nucleus, which is composed of two protons and two neutrons, plus a free neutron. Unlike deuterium, tritium is radioactive and does not occur in nature. It is commonly made in fission...
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Reactor Safety and Nuclear Waste (Encyclopedia of Global Resources)
One of the major factors limiting the development of nuclear power is concern about reactor safety. On March 28, 1979, there was a major accident in reactor number 2 at the Three Mile Island facility near Harrisburg, Pennsylvania. The accident began when one of the turbines stopped because of a minor malfunction. Although the fission reaction was stopped by the insertion of control rods very early in the accident, the uranium fuel continued to generate considerable heat because of the radioactive decay of the atoms produced when the uranium nuclei split. Water must continue to flow over the fuel rods long after fission stops in order to remove this heat. Through a series of errors by operating personnel at Three Mile Island, this flow of water was not maintained, and later, part of the core was not even submerged in water. As a result, much of the core overheated and melted. Although a core meltdown is a serious event, in this case, the exposure of people outside the reactor complex to radioactivity was negligible. Despite widespread concern over the Three Mile Island accident, one could argue that it demonstrated that pressurized-water reactors are actually quite safe. Such was not the public perception, however, and there were no new commercial reactor contracts signed in the United States between 1979 and 1996.
On April 26, 1986, a much more serious reactor accident occurred at the Chernobyl nuclear power...
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The Revival of Nuclear Energy (Encyclopedia of Global Resources)
By the early twenty-first century, concerns with carbon dioxide emissions from coal- and oil-fired power plants and increasing energy demand had led many people to advocate the use of nuclear power. When the cost of carbon emissions from coal- or gas-fired power plants are taken into account, nuclear power becomes more cost-effective than before. Several nations are planning or building nuclear power plants, with some scheduled to be operational in the second decade of the twenty-first century. Even some Scandinavian countries that had turned against nuclear energy are returning to consideration of its use. All told, as of 2009, some forty reactors were under construction in eleven countries, with another one hundred planned to be operational by 2020; more than two hundred others were under consideration. Many of these reactors in the planning stages are in Asia. India, for example, had six reactors under construction that were expected to be completed by 2010, one of which is a prototype breeder reactor. China has eleven operating reactors and intends to quadruple its capacity by 2020. In 2009, the U.S. government agreed to provide up to $122 billion in loan guarantees for building twenty-one new reactors. The first stage of this project is projected to add seven reactors by 2015 or 2016 at a cost ranging between $5 and $12 billion.
Increasing costs for oil and coal, coupled with environmental concerns, have...
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Further Reading (Encyclopedia of Global Resources)
Bodansky, David. Nuclear Energy: Principles, Practices, and Prospects. 2d ed. New York: Springer, 2004.
Caldicott, Helen. Nuclear Power Is Not the Answer. New York: New Press, 2006.
Eerkens, Jeff W. The Nuclear Imperative: A Critical Look at the Approaching Energy Crisis. Dordrecht, the Netherlands: Springer, 2006.
Grimston, Malcolm C., and Peter Beck. Double or Quits? The Global Future of Civil Nuclear Energy. London: Earthscan, 2002.
Heppenheimer, T. A. The Man-Made Sun: The Quest for Fusion Power. Boston: Little, Brown, 1984.
Herbst, Alan M., and George W. Hopley. Nuclear Energy Now: Why the Time Has Come for the World’s Most Misunderstood Energy Source. New York: John Wiley, 2007.
Hewitt, G. F., and John G. Collier. Introduction to Nuclear Power. 2d ed. New York: Taylor & Francis, 2000.
Hodgson, Peter E. Nuclear Power, Energy, and the Environment. London: Imperial College Press, 1999.
Lake, James A., Ralph G. Bennett, and John F. Kotek. “Next Generation Nuclear Power.” In Oil and the Future of Energy. Guilford, Conn.: Lyons Press, 2007.
Morris, Robert C. The Environmental Case for Nuclear Power: Economic, Medical, and Political Considerations. St. Paul, Minn.: Paragon House, 2000.
Murray, Raymond LeRoy. Nuclear Energy: An Introduction to the Concepts,...
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Background (Encyclopedia of Global Warming)
Since the 1950’s, countries such as the United States, the Soviet Union (now Russia), and France have relied on nuclear power as an energy source. Electric power is generated in nuclear power plants by fission reactors that heat water to turn turbines. Nuclear fission produces no greenhouse gases (GHGs). Mining uranium to power the reactors causes some environmental degradation, but the most significant drawbacks of nuclear energy are the high cost of reactor construction, the long lag time required to build reactors, and the difficulty of safely disposing of the nuclear waste generated by the reactors.
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Nuclear Energy as a Power Source (Encyclopedia of Global Warming)
When several countries began to build nuclear reactors to generate electric power in the 1950’s, nuclear energy was haled as the energy of the future. Uranium was and still is in plentiful supply, and supporters of nuclear power indicated it would provide inexhaustible electric power in the future. A few countries, most notably France, engaged in extensive reactor construction, and approximately 80 percent of France’s electric power now comes from nuclear power. Other countries, such as the United States, initially built several reactors. Support for nuclear power declined in the United States, however. No new power reactors were ordered after 1978. Approximately 20 percent of the electric power produced in the United States in the first decade of the twenty-first century came from nuclear energy.
Worldwide, approximately 16 percent of all electric power is generated by nuclear energy. In the first decade of the twenty-first century, some 440 nuclear power reactors were in operation in thirty countries. Six different types of power reactor were in operation, with research underway to expand this number. The most common reactor was the pressurized water reactor (268 reactors), followed by the boiling water reactor (94 reactors).
In spite of its initial problems, nuclear power may offer some advantages in dealing with climate change generated by burning fossil fuels. The operation of fission reactors...
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Drawbacks and Liabilities of Nuclear Energy (Encyclopedia of Global Warming)
Most of the twentieth century problems with nuclear energy remain, and some new issues have been raised as well. As fears of terrorism and so-called suitcase devices have increased, the need to control even relatively small amounts of nuclear material has become more urgent, and even well-protected nuclear power plants pose security risks. Although terrorists might prefer more high profile targets than reactors and upgrading nuclear fuel is difficult, the security threat may sway public opinion against expanding nuclear energy.
Moreover, there are no ideal methods of nuclear waste disposal. Wastes with low levels of radioactivity are currently being stored underground in the United States and elsewhere. The greatest source of concern is high-level radioactive waste, such as spent fuel rods, piping, and the like. France has long followed a policy of reprocessing and reusing spent fuel rods. This is an attractive solution, but the process produces weapons-grade plutonium as a by-product. The United States and most other countries have not adopted this practice, in part out of fear that some plutonium might fall into the wrong hands.
The United States and most other countries that use nuclear energy have not solved the problem of spent nuclear fuel as yet. The United States is developing an underground storage facility at Yucca Mountain in Nevada, but it is controversial and is unlikely to be...
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Timetables for Nuclear Deployment (Encyclopedia of Global Warming)
Nuclear energy may provide some help in mitigating global warming, but its impact is unlikely to be felt in the short run. In the United States, for example, the time required to obtain a permit to build a power reactor had increased to three and one-half years by the time the last reactor was permitted in 1978. Once a permit was issued, construction required around ten additional years. Although reactors have been constructed in other countries such as France or Russia in much shorter periods of time, they are complex facilities that cannot be constructed in short order. In some nations—such as Germany or the Scandinavian countries, where power reactors have been shut down—the largely antinuclear public will have to be convinced to allow new nuclear facilities to be contructed before any such project can be considered.
A large-scale expansion of nuclear energy is not likely until the 2020’s, if then. In the United States, sixteen utilities had announced plans for potential reactor construction by 2007, but it would be several years before any of these facilities could go online. Elsewhere, the situation was much the same.
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Context (Encyclopedia of Global Warming)
Nuclear energy has much to offer as an alternative to fossil fuels. Utilization of nuclear energy can help to provide a middle-term solution to the need for clean energy until ways can be found to enable cleaner, renewable sources such as solar energy to satisfy humanity’s energy needs. In addition to environmental factors, the increasing cost of oil will help make nuclear energy more attractive. Fears of terrorism, radiation leaks, and the difficulties surrounding nuclear waste disposal are obstacles to a resurgence of nuclear energy. The length of time required to build an operational reactor negates any advantages of nuclear energy as a short-term solution to energy-related GHG emissions. Public opinion appears to be becoming more favorably inclined toward nuclear energy, but a good deal of opposition remains. As with many issues concerning global warming, the longer the wait before construction of power reactors begins, the more costly the process will be, and the less help the reactors will provide in combating the increasing emission of GHGs.
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Further Reading (Encyclopedia of Global Warming)
Caldicott, Helen. Nuclear Power Is Not the Answer. New York: New Press, 2006. Argues that the various issues facing nuclear energy are so great as to outweigh the advantages of nuclear power.
Deutch, John M., and Ernest J. Moniz. “The Nuclear Option,” Scientific American, September, 2006, 75-83. Indicates that a significant expansion of nuclear power could reduce GHG emissions in a cost-effective fashion.
Herbst, Alan M., and George W. Hopley. Nuclear Energy Now. New York: John Wiley, 2007. Primarily economic analysis of nuclear energy that advocates its adoption.
Lake, James A., Ralph G. Bennett, and John F. Kotek. “Next Generation Nuclear Power.” In Oil and the Future of Energy. Guilford, Conn.: Lyons Press, 2007. Examines the evolving technology of nuclear reactor construction.
Macfarlane, Allison M., and Rodney C. Ewing, eds. Uncertainty Underground. Cambridge, Mass.: MIT Press, 2006. Useful collection of essays about the technology of dealing with high-level nuclear waste at Yucca Mountain, as well as public policy issues.
Morris, Robert C. The Environmental Case for Nuclear Power. St. Paul, Minn.: Paragon House, 2000. Contrasts nuclear energy favorably with fossil fuels in terms of their environmental and medical effects.
Nuttall, W. J. Nuclear Renaissance: Technologies and Policies for the Future of Nuclear Power....
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Nuclear Energy (Encyclopedia of Science and Religion)
Nuclear energy, strictly conceived, has received rather scant attention within the literature of science and religion. However, if the focus is broadened to include nuclear technologyhat is, nuclear energy and nuclear weapons considered togetherhen there is a modest increase in its treatment.
Benefits and risks
Nuclear energy has long been viewed as an alternative energy source to coal and petroleum, which are currently the principal sources of energy. Coal and petroleum provide efficient sources of energy, but their combustion also generates considerable carbon dioxide that escapes into the atmosphere. Although a few dissenters remain, the vast majority of climatologists hold that the build up of carbon dioxide in the atmosphere creates a greenhouse effect. This greenhouse effect dramatically warms the planet, which leads, in turn, to global climate change, resulting in different impacts on different regions of the planet.
Nuclear energy provides an especially attractive alternative to coal and petroleum because it does not contribute to the concentration of carbon dioxide in the atmosphere. Shifting to nuclear energy could potentially lead to a cleaner, healthier environment without a reduction in the human consumption of energy. However, the benefits of nuclear energy must be weighed against its substantial costs and risks. The principal cost of nuclear energy occurs with the safe disposal of radioactive wastes. In addition to the costs of disposal, there is the risk that nuclear radiation could be released into the environment, either at the nuclear power plant or at the site of waste disposal. Such a release could be accidental, the result of equipment malfunction or human error. There is also the risk of an intentional release of nuclear radiation as an act of terrorism. Whether accidental or intentional, such a release could potentially destroy all biotic life in the affected area and make the area sterile for life for the foreseeable future.
Although as of 2002 there have been no intentional releases of nuclear radiation into the environment, there have been two serious accidents at nuclear power plants. In 1979, there was an accident at the Three Mile Island nuclear power plant in Pennsylvania. There was another accident in 1986 at the Chernobyl nuclear power plant in Ukraine. Although very little nuclear radiation escaped from the Three Mile Island accident, nuclear radiation did escape from the Chernobyl accident, causing substantial ecological damage and the deaths of a number of people.
Within the science and religion literature, Ian Barbour provides one of the few focused treatments of nuclear energy in his book Ethics in an Age of Technology (1993). Barbour begins his examination with a discussion of risk. If risk is defined as the probability of an accident multiplied by the magnitude of its consequences, then the risk posed by nuclear energy is low, compared to other daily activities, such as driving a car. However, Barbour argues that evaluations of such technological risks must also be influenced by assumptions about human nature and social institutions. Taking a Christian religious perspective, Barbour argues that the individual and social sin inherent in the human condition calls for extreme caution in the development of nuclear energy because the risks and consequences are so high.
Shifting his focus to the safe disposal of radioactive wastes, Barbour identifies three ethical issues. First, Barbour notes that an issue of regional justice arises because radioactive waste disposal imposes extreme risks for a local population in order to provide a national benefit for everyone. Intergenerational justice raises a second ethical issue. The present generation would enjoy the benefits of nuclear energy, but passes on some of the burdens and risks of waste disposal to future generations. Finally, Barbour identifies the loss of public confidence in governments and the energy industry as a third ethical issue. His point here is that historically government and industry have been secretive and have failed to protect the public, rather than being transparent and promoting public discourse concerning the benefits, costs, and risks of nuclear energy. Barbour believes that more promising energy alternatives lie in energy conservation and in the use of other renewal energy sources, such as solar power.
In the 1980s, several religious writers warned that nuclear weapons and nuclear war threatened not only human life but the ecological viability of the planet. Two Christian theologians, Gordon Kaufman and Sallie McFague, argued further that these interconnected challenges were rooted in what has become a flawed understanding of God's power. In Theology for a Nuclear Age (1985), Kaufman argues that the threat of nuclear war and annihilation elicits two contrasting responses from traditional Christian conceptions of God. On the one hand, nuclear annihilation is interpreted in eschatological terms as God's action to bring the present age to an end. On the other hand, the threat of nuclear war is discounted because of the view that an almighty creator God, who loves humans and the rest of creation, would not allow such a disaster to occur. Kaufman notes that both responses have the effect of obscuring and undermining the responsibility that humans have for their actions. While the traditional understanding of God as omnipotent may have been appropriate for earlier times, Kaufman argues that this understanding is no longer appropriate in a nuclear age. In light of the threat of nuclear weapons, Kaufman proposes that Christian theologians need to reconceive of God's power, moving from a dualistic to an interdependent understanding. This would require theologians to rethink their formulation of the symbols "God" and "Christ." McFague concurs with Kaufman's analysis in her book Models of God: Theology for an Ecological, Nuclear Age (1987). As alternative models for thinking about God, McFague proposes mother, lover, and friend.
While both Kaufman and McFague were thinking initially of the threat of nuclear annihilation, they both extend their analyses to include ecological concerns. Thus, whether conceived broadly as nuclear technology, or more narrowly as nuclear energy, the literature of science and religion has consistently seen critical ecological implications for the planet.
See also ECOLOGY; ECOLOGY, ETHICS OF; ECOLOGY, RELIGIOUS AND PHILOSOPHICAL ASPECTS; ECOLOGY, SCIENCE OF; GREENHOUSE EFFECT
Barbour, Ian. Ethics in an Age of Technology. San Francisco: Harper, 1993.
Kaufman, Gordon D. Theology for a Nuclear Age. Manchester, UK: Manchester University Press, 1985.
McFague, Sallie. Models of God: Theology for an Ecological, Nuclear Age. Philadelphia: Fortress Press, 1987.
RICHARD O. RANDOLPH