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Papers > Science > Nuclear energy By April R Catchings 28 page term paper
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Nuclear energy By April R Catchings 28 page term paper |
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Nuclear energy, also called atomic energy, is the powerful energy released by changes in the nucleus (core) of atoms. The heat and light of the sun result from nuclear energy. Scientists and engineers have found many uses for this energy, including the production of electric energy and the explosion of nuclear weapons. Scientists knew nothing about nuclear energy until the early 1900s, though they knew that all matter consists of atoms. ... A huge amount of energy is concentrated in the nucleus because of this force. The next step was to make nuclei let go of much of that energy. Scientists first released nuclear energy on a large scale at the University of Chicago in 1942, three years after World War II began. ... Since 1945, peaceful uses of nuclear energy have been developed. The energy released by nuclei creates large amounts of heat. This heat can be used to make steam, and the steam can be used to generate electric energy. Engineers have built devices called nuclear reactors to produce and control nuclear energy. A nuclear reactor operates somewhat like a furnace. ... And instead of burning in the reactor, the uranium fiss power production is by far the most important peaceful use of nuclear energy. Nuclear energy also powers some submarines and other ships. In addition, the fission that produces nuclear energy is valuable because it releases particles and rays called nuclear radiation that have uses in medicine, industry, and science. However, nuclear radiation can be extremely dangerous. ... Almost all the worlds electric energy is produced by hydroelectric and thermal power plants. ... Therefore, many experts predict that nuclear power will become increasingly important. Worldwide distribution of nuclear energy. In the mid-1990s, about 425 nuclear power reactors operated in about 30 countries. Nuclear power plants produced less than 20 percent of the worlds electric energy. The United States had about 110 nuclear reactors and was the worlds largest producer of nuclear energy. ... Other countries, notably France and Japan, have a large nuclear power generating capacity. Advantages and disadvantages of nuclear energy. Nuclear power plants have two main advantages over fossil-fuel plants. (1) Once built, a nuclear plant can be less expensive to operate than a fossil-fuel plant, mainly because a nuclear plant uses a much smaller volume of fuel. ... However, nuclear power plants have three major disadvantages. These drawbacks have slowed the development of nuclear energy in the United States. (1) Nuclear plants cost more to build than fossil-fuel plants. (2) Because of the need to assure that hazardous amounts of radioactive materials are not released, nuclear plants must meet certain government regulations that fossil-fuel plants do not have to meet. For example, a nuclear plant must satisfy the government that it can quickly and automatically deal with any kind of emergency. (3) Used nuclear fuel produces dangerous radiation long after it has been removed from the reactor. The full development of nuclear energy. Many experts believe that the benefits of nuclear energy outweigh any problems involved in its production. ... Canada, Germany, Russia, the United States, and some other countries have enough coal to meet their energy requirements for hundreds of years at present rates of use. ... If nuclear energy were fully developed, it could completely replace oil and coal as a source of electric power. But a number of problems must be solved before nuclear energy can be fully developed. ... Therefore, for nuclear energy to replace other energy sources, it must be based on fuel that is much more plentiful than U-235. NUCLEAR ENERGY/The science of nuclear energy The process by which a nucleus releases energy is called a nuclear reaction. To understand the various types of nuclear reactions, a person must know something about the nature of matter. ... However, electrons do not play an active part in nuclear reactions. ... Extremely strong forces, called nuclear forces, hold the protons and neutrons together in the nucleus. The nuclear forces of each type of nucleus determine the amount of energy that would be required to release its neutrons and protons. ... The uranium isotope that almost all nuclear reactors use as fuel has 143 neutrons, and so its mass number is 235. ... Nuclear reactions A nuclear reaction changes the structure of a nucleus. ... Three types of nuclear reactions release useful amounts of energy. These reactions are (1) radioactive decay, (2) nuclear fission, and (3) nuclear fusion. ... The mass is lost because it changes into energy. ... The process releases energy chiefly in the form of particles and rays called nuclear radiation. ... Nuclear reactors produce radioactive isotopes artificially. Nuclear radiation accounts for about 10 percent of the energy produced in a reactor. Nuclear radiation consists largely of alpha and beta particles and gamma rays. ... Nuclear fission is the splitting of heavy nuclei to release energy. All commercial nuclear reactors produce energy in this way. ... Nuclear fission occurs when the bombarding particle splits a nucleus in the target material into two parts called fission fragments. ... The energy is released in many forms. But most of the energy released by fission eventually takes the form of heat. ... Uranium also makes a good nuclear reactor fuel because it can sustain a continuous series of fission reactions. As a result, uranium can produce a steady supply of energy. ... Chain reactions can produce an enormous amount of energy. Only nuclei that have many more neutrons than protons, such as uranium nuclei, can produce a nuclear chain reaction. The scarce uranium isotope U-235 is the only natural material that nuclear reactors can use to produce a chain reaction. ... A fast breeder reactor that converts U-238 to plutonium can greatly extend the use of uranium as an energy resource. ... Nuclear fusion occurs when two lightweight nuclei fuse (combine) and form a nucleus of a heavier element. ... The lost mass has therefore been changed into energy. Fusion reactions that produce large amounts of energy can be created by means of extremely intense heat. ... Thermonuclear reactions produce the energy of both the sun and the hydrogen bomb. ... Scientists have not yet succeeded in harnessing the energy of fusion to produce electric energy. ... One barrel of seawater contains enough of these substances to produce as much energy as the burning of about one-fifth of a barrel of oil. ... The plasma must therefore be kept away from the walls of the container long enough for its nuclei to fuse and produce usable amounts of energy. ... All the fusion devices thus far developed, however, use much more energy than they create. ... NUCLEAR ENERGY/How nuclear energy is produced All large commercial nuclear power plants produce energy by fissioning U-235. ... 28 percent of all natural uranium is U-238. ... Nuclear fuel requires special processing before and after it is used. ... nuclear power industry. ... Most nuclear power plants cover 200 to 300 acres (80 to 120 hectares). The majority are built near a large river or lake because nuclear plants require enormous quantities of water for cooling purposes. A nuclear plant consists of several main buildings, one of which houses the reactor and its related parts. ... The concrete and steel guard against the escape of radioactive material from an accidental leak in the nuclear reactor. Power reactors that are used in nuclear power plants in the United States consist of three main parts: (1) a reactor, or pressure, vessel; (2) a core; and (3) a set of control rods. ... The core contains the nuclear fuel, in which the fission chain reaction occurs. ... Neutrons can pass from the fuel through the tube walls, but most other nuclear particles cannot. ... It carries the heat from the reactor to an energy conversion system. Thus, the coolant keeps the fuel and cladding from getting too hot, and it transfers energy to a place where electricity can be generated. ... nuclear plants are of two main types. ... Most nuclear plants in the United States use pressurized water reactors. ... In producing electric energy, a nuclear plants steam turbines and electric generators work like those in a fossil-fuel plant. ... To help solve the problem of thermal pollution, most new nuclear plants have cooling towers. ... The chief hazards of nuclear power production result from the great quantities of radioactive material that a reactor produces. ... nuclear plants. ... Safe disposal of these wastes is one of the most difficult problems involved in nuclear power. Most nuclear plants need to replace their fuel assemblies only about once a year. ... Nuclear plants cool the assemblies by storing them underwater in specially designed storage pools. In the United States, the federal government is working on guidelines for the safe and permanent disposal of nuclear wastes. ... A law passed by Congress in 1982 required the federal government to build two sites for nuclear wastes from commercial power plants. ... A storage site for nuclear waste must lie in a highly stable area that is free of earthquakes, faulting, and other geologic activity. ... In the meantime, commercial nuclear power plants in the United States continue to store used fuel assemblies and other wastes in pools of water on the plant grounds. ... Under this plan, nuclear plants would ship their used fuel assemblies to the reprocessing plants for removal of Pu-239 and unused U-235. These radioactive isotopes would then be recycled into fuel for nuclear reactors. ... In every country that has a nuclear energy industry, the government plays a role in the industry. |
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Title: Nuclear energy By April R Catchings 28 page term paper
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