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1 Your web browser (Safari 7) is out of date. For more security, comfort and the best experience on this site: Update your browser Ignore NU CL EAR ENERGY For the complete encyclopedic entry with media resources, visit: Nuclear energy is the energy in the nucleus, or core, of an atom. Atoms are tiny units that make up all matter in the universe. Energy is what holds the nucleus together. There is a huge amount of power in an atoms dense nucleus. In fact, the power that holds the nucleus together is officially called the "strong force. Nuclear energy can be used to create electricity, but it must first be released from the atom. In nuclear fission, atoms are split to release the energy. A nuclear reactor, or power plant, is a series of machines that can control nuclear fission to produce electricity. The fuel that nuclear reactors use to produce nuclear fission is pellets of the element uranium. In a nuclear reactor, atoms of uranium are forced to break apart. As they split, the atoms release tiny particles called fission products. Fission products cause other uranium atoms to split, starting a chain reaction. The energy released from this chain reaction creates heat. The heat created by nuclear fission warms the reactors cooling agent. A cooling agent is usually water, but some nuclear reactors use liquid metal or molten salt. The cooling agent, heated by nuclear fission, produces steam. The steam turns turbines, or wheels turned by a flowing current. The turbines drive generators, or engines that create electricity. Rods of material called nuclear poison can adjust how much electricity is produced. Nuclear poisons are materials, such as a type of the element xenon, that absorb some of the fission products created by nuclear fission. The more rods of nuclear poison that are present during the chain reaction, the slower 1 of 11

2 and more controlled the reaction will be. Removing the rods will allow a stronger chain reaction and create more electricity. About 15 percent of the worlds electricity is generated by nuclear power plants. The United States has more than 100 reactors, although it creates most of its electricity from fossil fuels and hydroelectric energy. Nations such as Lithuania, France, and Slovakia create almost all of their electricity from nuclear power plants. Nuclear Food: Uranium Uranium is the fuel most widely used to produce nuclear energy. Thats because uranium atoms split apart relatively easily. Its also a very common element, found in rocks all over the world. However, the specific type of uranium used to produce nuclear energy, called U-235, is rare. U-235 makes up less than one percent of the uranium in the world. Although some of the uranium the United States uses is mined in this country, most is imported. The U.S. gets uranium from Australia, Canada, Kazakhstan, Russia, and Uzbekistan. Once uranium is mined, it must be extracted from other minerals. It must also be processed before it can be used. Because nuclear fuel can be used to create nuclear weapons as well as nuclear reactors, only nations that are part of the Nuclear Non-Proliferation Treaty (NPT) are allowed to import uranium or plutonium, another nuclear fuel. The treaty promotes the peaceful use of nuclear fuel, as well as limiting the spread of nuclear weapons. A typical nuclear reactor uses about 200 tons of uranium every year. Complex processes allow some uranium and plutonium to be re-enriched or recycled. This reduces the amount of mining, extracting, and processing that needs to be done. 2 of 11

3 Nuclear Energy and People Nuclear energy produces electricity that can be used to power homes, schools, businesses, and hospitals. The first nuclear reactor to produce electricity was located near Arco, Idaho, in the U.S. The Experimental Breeder Reactor began powering itself in The first nuclear power plant designed to provide energy to a community was established in Obninsk, Russia, in Building nuclear reactors requires a high level of technology, and only the countries that have signed the Nuclear Non-Proliferation Treaty can get the uranium or plutonium that is required. For these reasons, most nuclear power plants are located in the developed world. Nuclear power plants produce renewable, clean energy. They do not pollute the air or produce greenhouse gases. They can be built in urban or rural areas, and do not radically alter the environment around them. The steam powering the turbines and generators is ultimately recycled. It is cooled down in a separate structure called a cooling tower. The steam turns back into water and can be used again to produce more electricity. Excess steam is simply recycled into the atmosphere, where it does no harm as clean water vapor. However, the byproduct of nuclear energy is radioactive material. Radioactive material is a collection of unstable atomic nuclei. These nuclei lose their energy and can affect many materials around them, including organisms and the environment. Radioactive material can be extremely toxic, causing burns and increasing the risk for cancers, blood diseases, and bone decay. Radioactive waste is what is left over from the operation of a nuclear reactor. Radioactive waste is mostly protective clothing worn by workers, tools, and cloths that have been in contact with radioactive dust. Radioactive waste is longlasting. Materials like clothes and tools can stay radioactive for thousands of 3 of 11

4 years. The government regulates how these materials are disposed of so they dont contaminate anything else. Used fuel and rods of nuclear poison are extremely radioactive. The used uranium pellets must be stored in special containers that look like large swimming pools. Water cools the fuel and insulates the outside from contact with the radioactivity. Some nuclear plants store their used fuel in dry storage tanks above ground. The storage sites for radioactive waste have become very controversial in the United States. For years, the government planned to construct an enormous nuclear waste facility near Yucca Mountain, Nevada, for instance. Environmental groups and local citizens protested the plan. They worried about radioactive waste leaking into the water supply and the Yucca Mountain environment, about 130 kilometers (80 miles) from the large urban area of Las Vegas, Nevada. Although the government began investigating the site in 1978, it stopped planning for a nuclear waste facility in Yucca Mountain in Chernobyl Critics of nuclear energy worry that the storage facilities for radioactive waste will leak, crack, or erode. Radioactive material could then contaminate the soil and groundwater near the facility. This could lead to serious health problems for the people and organisms in the area. All communities would have to be evacuated. This is what happened in Chernobyl, Ukraine, in A steam explosion at one of the power plants four nuclear reactors caused a fire, called a plume. This plume was highly radioactive, creating a cloud of radioactive particles that fell to the ground, called fallout. The fallout spread over the Chernobyl facility, as well as the surrounding area. The fallout drifted with the wind, and the particles entered the water cycle as rain. Radioactivity traced to Chernobyl fell as rain over Scotland and Ireland. Most of the radioactive fallout fell in Belarus. 4 of 11

5 The environmental impact of the Chernobyl disaster was immediate. For kilometers around the facility, the pine forest dried up and died. The red color of the dead pines earned this area the nickname the Red Forest. Fish from the nearby Pripyat River had so much radioactivity that people could no longer eat them. Cattle and horses in the area died. More than 100,000 people were relocated after the disaster, but the number of human victims of Chernobyl is difficult to determine. The effects of radiation poisoning only appear after many years. Cancers and other diseases can be very difficult to trace to a single source. Future of Nuclear Energy Nuclear reactors use fission, or the splitting of atoms, to produce energy. Nuclear energy can also be produced through fusion, or joining (fusing) atoms together. The sun, for instance, is constantly undergoing nuclear fusion as hydrogen atoms fuse to form helium. Because all life on our planet depends on the sun, you could say that nuclear fusion makes life on Earth possible. Nuclear power plants do not have the capability to safely and reliably produce energy from nuclear fusion. Its not clear whether the process will ever be an option for producing electricity. Nuclear engineers are researching nuclear fusion, however, because the process will likely be safe and cost-effective. Vocabulary Term absorb verb to soak up. atmosphere atom 5 of 11 layers of gases surrounding a planet or other celestial body. the basic unit of an element, composed of three major parts: electrons, protons, and neutrons.

6 Term boiling-water type of nuclear power plant where steam is used to reactor power generators. burn injury caused by heat. byproduct substance that is created by the production of another material. cancer growth of abnormal cells in the body. capability ability to perform a task. cattle cows and oxen. chain reaction series of events where the previous event causes the next event. Chernobyl (1986) major accident at the nuclear power plant in disaster Chernobyl, Ukraine. clean energy electrical energy that does not pollute the atmosphere, water, or earth. contaminate verb to poison or make hazardous. continental the movement of continents resulting from the motion of drift tectonic plates. controversial questionable or leading to argument. cooling agent material used in a nuclear power plant, usually water, that is warmed by heat from nuclear fission. cooling tower structure in a nuclear power plant where steam is cooled until it turns back into water. current steady, predictable flow of fluid within a larger body of that fluid. decay verb to rot or decompose. determine verb to decide. developed a nation that has high levels of economic activity, health country care, and education. disaster terrible and damaging event. 6 of 11

7 Term electricity set of physical phenomena associated with the presence and flow of electric charge. emission discharge or release. enormous adjectivevery large. environmental incident or activity's total effect on the surrounding impact environment. erode verb to wear away. evacuate verb to leave or remove from a dangerous place. extract verb to pull out. facility a building or room that serves a specific function. fallout airborne radioactive particles that eventually fall to the ground, usually the result of a nuclear explosion. forest ecosystem filled with trees and underbrush. fossil fuel coal, oil, or natural gas. Fossil fuels formed from the remains of ancient plants and animals. fuel material that provides power or energy. fuse verb to combine or meld together. generate verb to create or begin. generator machine that converts one type of energy to another, such as mechanical energy to electricity. geothermal energy heat energy generated within the Earth. gas in the atmosphere, such as carbon dioxide, methane, greenhouse water vapor, and ozone, that absorbs solar heat gas reflected by the surface of the Earth, warming the atmosphere. groundwater water found in an aquifer. helium a light, colorless gas with the chemical symbol He. 7 of 11

8 hydroelectric energy Term energy generated by moving water converted to electricity. Also known as hydroelectricity. chemical element with the symbol H, whose most hydrogen common isotope consists of a single electron and a single proton. immediate adjectivequickly or right away. import good traded from another area. insulate verb to cover with material to prevent the escape of energy (such as heat) or sound. liquid state of matter with no fixed shape and molecules that remain loosely bound with each other. malfunction verb to not work correctly. metal category of elements that are usually solid and shiny at room temperature. mineral inorganic material that has a characteristic chemical composition and specific crystal structure. mining process of extracting ore from the Earth. molten adjectivesolid material turned to liquid by heat. nuclear energy energy released by reactions among the nuclei of atoms. nuclear process where the nucleus of an atom splits, releasing fission energy. process where the nuclei of one element, usually nuclear fusion hydrogen, fuse with each other to form the nuclei of another element, usually helium. Nuclear Non- (1970) international agreement to limit the spread of Proliferation nuclear weapons. Treaty (NPT) nuclear materials that absorb some of the products produced in poison nuclear fission reactions. 8 of 11

9 nuclear reactor nuclear waste nuclear weapon nucleus machinery that can control nuclear fission, usually producing electricity. material that has been exposed to radioactivity. Also called radioactive waste. explosive device that draws power from the splitting and combining of atomic nuclei. positively charged central region of an atom, containing protons and neutrons. particle small piece of material. pellet small, rounded object. pine type of evergreen tree with needle-shaped leaves. plate tectonics movement and interaction of the Earth's plates. plume single, upward flow of a fluid, such as water or smoke. plutonium pollute verb chemical element with the symbol Pu. Used to make nuclear weapons and as a power source. to introduce harmful materials into a natural environment. power plant industrial facility for the generation of electric energy. pressurizedwater reactor radiation poisoning type of nuclear power plant where a flow of water is used to power generators. set of illnesses, including burns, cancers, and organ damage, that results from exposure to radioactive material. radically adverb completely or extremely. radioactive radioactive waste Term having unstable atomic nuclei and emitting subatomic adjective particles and radiation. byproduct of nuclear fission that emits a type of heat, or radiation, that can damage the tissue of living organisms. recycle verb to clean or process in order to make suitable for reuse. 9 of 11

10 Red Forest dead pine forest surrounding the nuclear power plant in Chernobyl, Ukraine. regulate verb to determine and administer a set of rules for an activity. relocate rural area salt verb to move a residence or business from one place to another. steam water vapor. regions with low population density and large amounts of undeveloped land. Also called "the country." (sodium chloride, NaCl) crystalline mineral often used as a seasoning or preservative for food. storage tank large container in which liquid is usually stored. strong force technology Three Mile Island disaster toxic turbine Term power that binds parts of an atom's nucleus together. Also called the nuclear force. the science of using tools and complex machines to make human life easier or more profitable. (1979) accident at a nuclear reactor near Harrisburg, Pennsylvania. adjectivepoisonous. machine that captures the energy of a moving fluid, such as air or water. U-235 uranium isotope often used to produce nuclear fission. universe all known matter, energy, and space. unstable atomic nuclei radioactive material, or the nucleus of an atom that has an unbalanced number of protons or neutrons. Unstable atomic nuclei lose energy by emitting radiation and subatomic particles. uranium chemical element with the symbol U. Fuel used to produce nuclear energy. 10 of 11

11 Term urban area developed, densely populated area where most inhabitants have nonagricultural jobs. vapor visible liquid suspended in the air, such as fog. victim person or organization that suffers from the act of another. water cycle movement of water between atmosphere, land, and ocean. xenon chemical element with the symbol Xe. Articles & Profiles National Geographic News: Radioactive Rabbit Droppings Help Spur Nuclear Cleanup National Geographic Environment: Nuclear Power Rising a Comeback Audio & Video National Geographic Channel: World's Toughest Fixes Nuclear Turbine Websites U.S. Department of Energy: Nuclear Energy National Geographic Society. All rights reserved. 11 of 11