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nuclear - ENVST 110 Nuclear Energy Nuclear Power Nuclear...

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ENVST 110 Nuclear Energy Nuclear Power Nuclear power is used in many countries. Some countries, like France get over 70% of their electricity from nuclear. http://www.uic.com.au/nfc.htm
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ENVST 110 Nuclear Energy Nuclear Fuel Cycle : ( http://www.uic.com.au/nfc.htm ) http://news.bbc.co.uk/2/shared/spl/hi/sci_nat/05/nuclear_fuel/html/mining.stm Uranium is the basic raw material of both civilian and military nuclear programmes. It is extracted from either open-cast pits or by underground mining. Although uranium occurs naturally all over the world, only a small fraction is found in concentrated ores. When certain atoms of uranium are split in a chain reaction, energy is released. This process is called nuclear fission. In a nuclear power station this fission occurs slowly, while in a nuclear weapon, very rapidly. In both instances, fission must be very carefully controlled. Nuclear fission works best if isotopes - atoms with the same number of protons, but different numbers of neutrons - of uranium 235 (or plutonium 239) are used. These isotopes have almost identical chemical properties, but different nuclear properties. Uranium-235 is known as a "fissile isotope" because of its propensity to split in a chain reaction, releasing energy in the form of heat. When a U-235 atom splits, it emits two or three neutrons. When other U-235 atoms are present, these neutrons collide with them causing the other atoms to split, producing more neutrons. A nuclear reaction will only take place if there are enough U-235 atoms present to allow this process to continue as a self-sustaining chain reaction. This requirement is known as "critical mass". However,
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ENVST 110 Nuclear Energy every 1,000 atoms of naturally-occurring uranium contain only seven atoms of U-235, with the remaining 993 being denser U-238. Relative Abundance of Uranium Isotopes Isotope U-238 U-235 U-234 Natural Abundance (%) 99.27 0.72 0.0055 Half-life (years) 4.47 billion 700 million 246,000 Uranium isotopes can be separated to increase the concentration of one isotope relative to another. This process is called "enrichment." The enriched fraction has increased U- 235. Uranium-235 is better for nuclear power reactors ( about 4% U-235 ), and for making nuclear weapons ( about 99% U-235 requiring many centrifuges working in concert ). The process produces huge quantities of uranium that are depleted in U-235, but are almost pure U-238, called depleted uranium , or DU. Generating Electricity from Nuclear Fission: The fission of all the nuclei of one kilogram of Uranium-235 produces as much energy as the burning of 2,500 tons of coal. http://web.ccr.jussieu.fr/radioactivite/english/indispensable.htm
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ENVST 110 Nuclear Energy Wastes (http://www.world-nuclear.org/info/inf03.html ) Wastes from the nuclear fuel cycle are categorised as high-, medium- or low-level wastes by the amount of radiation that they emit. These wastes come from a number of sources and include: low-level waste produced at all stages of the fuel cycle; intermediate-level waste produced during reactor operation and by reprocessing;
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