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Nuclear Energy

Nuclear Energy. Ch. 16 Environmental Science. 16.1 Atoms and Radioactivity. All matter is made of atoms Atoms have Proton Electron Neutrons Nucleus contains protons and neutrons has most of the mass Neutral protons = electrons. Atoms and isotopes. Properties determined by protons

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Nuclear Energy

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  1. Nuclear Energy Ch. 16 Environmental Science

  2. 16.1 Atoms and Radioactivity • All matter is made of atoms • Atoms have • Proton • Electron • Neutrons Nucleus contains protons and neutrons has most of the mass Neutral protons = electrons

  3. Atoms and isotopes • Properties determined by protons • Proton number never changes for that element • Atomic number is proton number

  4. Mass number = protons + neutrons • Isotopes – atoms of the same element that have different numbers of neutrons • Uranium • 92 protons, 146 neutrons • Mass number 238 • Isotope U-235, 143 neutrons

  5. radioactivity • Radioactive atoms • Unstable • Decay • Emit particles and energy from nuclei

  6. Radiation 1) alpha particles - 2 protons and 2 neutrons, cannot penetrate skin or paper, but dangerous in lung 2) beta particles – high speed electron, can penetrate skin, stopped with aluminum foil 3) gamma rays – electromagnetic radiation, can go through body. Can be blocked by several cm of lead or concrete, or 1 m of water

  7. Half-life • The amount of time it takes for half the atoms in a sample of radioactive element to decay • May be a few seconds to billions of years

  8. 16.2 reactions and reactors • Nuclear fission • A reaction in which the nucleus of a large atom is split into smaller nuclei • Emits large amounts of energy • May be used for electricity

  9. fission

  10. Nuclear Fission • U-235 most commonly used • Chain reaction releases energy

  11. Nuclear reactors • Nuclear reactor vessel • Where the fission of U-234 takes place • Used to produce electricity • Heat produced by fission instead of fossil fuels

  12. meltdown

  13. Breeder reactors • Changes U-238 into plutonium-239 • Pu-239 used as nuclear fuel • Not used in the US because of terrorism • Plutonium used in atomic bombs • Nuclear Reaction-Plutonium video

  14. 19.3 radioactive waste • Nuclear power plants produce radioactive waste • Radiation unhealthy to living cells • May cause cancer and genetic mutations

  15. High level waste – emit large amounts of radiation • Uranium fuel rods • Control rods • Water used to control the chain reactions • Medium-level and low-level waste are not as radioactive, although more of these are generated

  16. Waste disposal • Difficult to dispose of • Long half-lives – takes 1000’s of years to decay. • Sealed on containers that will not decay • Stored underground-geologically stable • Yucca Mountains, Nevada • Huge environmental concerns

  17. Safety and cost • Meltdown- chain reaction goes out of control and melts the reactor core. • Chernobyl, Ukraine, April 1986-meltdown • 116,000 people permanently left • At least 15,000 cases of cancer • Old plant, lacked many safety features • Utube • 20th anniv. Utube

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