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Nuclear

Nuclear. Radiation, energy and particles. Nuclear reactions. Fission (nuclear decay): a nucleus breaks apart into two or more smaller particles. *This is the type of reaction that occurs in nuclear power plants and nuclear bombs.

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Nuclear

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  1. Nuclear Radiation, energy and particles

  2. Nuclear reactions Fission (nuclear decay): a nucleus breaks apart into two or more smaller particles. *This is the type of reaction that occurs in nuclear power plants and nuclear bombs. Fusion: Two or more nuclei combine to make one larger nuclei *This is the type of reaction that occurs in stars and the core of planets.

  3. Website http://www.atomicarchive.com/Movies/index.shtml

  4. Natural Radioactive Decay • Alpha particles: helium nucleus, large, slow moving, low penetration, stopped by thick cardboard (if they enter the body through an opening, they do a lot of tissue damage) • Beta particles: electrons, small, faster than alpha particles, higher penetration, stopped by thick wood. Less tissue damage than Alpha • Gamma rays: energy, fastest, most penetrating, most tissue damage, stopped by thick concrete or lead.

  5. Symbols for Nuclear Decay • Alpha particle: • Beta particle: • Gamma ray:

  6. Example problems: Decay Reactions • Radium-226 undergoes alpha decay. • Lead-210 undergoes beta decay. • Cobalt-60 undergoes beta decay. • Americium-241 undergoes alpha decay.

  7. Effects of Radiation 0-25 rem No immediate observable effects 25-50 Small decrease in white blood cell count. 50-100 Marked decrease in white blood cell count. 100-200 Nausea, vomiting, loss of hair, blood cells die (radiation sickness) 200-300 Hemorrhaging, ulcers, death 300-500 Acute radiation sickness, 50% die in a few weeks. >700 100% die

  8. Exposure to Radiation Cosmic Rays (higher when flying in a plane) Radioisotopes in rocks, soil, groundwater Radioisotopes in the air Fallout from nuclear weapons testing Medical X-rays

  9. Half-life • Half-life is the amount of time required for half of a sample of radioactive material to decay. Carbon-14 5730 years Uranium-238 4.5 x 109 years Calcium-47 4.5 days Cobalt-60 5.26 years

  10. Half-life equations • Age or time elapsed = (length of half life)(number of half-lives) • Fraction left = (1/2)^number of half lives • Amount left = (fraction left)(original amount) C-14 original amount is 15.3 disintegrations/min (anything that was alive)

  11. Half-life Example problem #1 • A sample of wood is measured with a geiger counter and determined to give off 1.91disintegrations/min. How old is the piece of wood?

  12. Half-life Ex. #2 • A laboratory needs 1g of Au-191 to run an experiment. The half life of Au-191 is 3.4 hours. What mass of Au-191 will need to be shipped it the travel time from the supplier is 17 hours?

  13. Half-life Ex. #3 • The half-life for Cobalt-60 is 5.26 years. How old is a piece of Co-60 that has a fraction left of 0.031 out of the original sample which is still hasn’t decayed?

  14. Nuclear Binding Energy • When a nucleus forms, the mass of the nucleus is less that its component parts (protons and neutrons). This difference in mass is call the mass defect. • The equation to find the nuclear binding energy is: E = mc2 (c is the speed of light)

  15. Nuclear energy Ex. #1 • How much energy is given off when an element has a mass defect of 0.00089g?

  16. Nuclear Power Plants • Nuclear Power plants harness the nuclear binding energy from fission reactions. These are caused by shooting a neutron into U-235, making it unstable so that is breaks down into smaller nuclei and releases more neutrons. This causes a chain reaction and those neutrons his other U-235 nuclei, propagating further reactions.

  17. A Nuclear Power Plant Animation I have to minimize this and open another file to show you this.

  18. Parts of a Nuclear Plant • Fuel Rods: Uranium or Plutonium, they supply the neutrons • Control Rods: Boron or Cadmium, they absorb the neutrons • Moderator: Water, it slows the neutrons • Encasement: Concrete & Lead, keeps the radiation from going out into the environment.

  19. Dealing with Nuclear Waste • Most nuclear waste is placed into waste containers, then bundled into a larger waste container and buried 1000-2000m under the ground in mines. The problem, movement of the earth’s plates can result in movement of waste and/or a radiation leak. Total waste by 2000: 40,000 metric tons

  20. Positive Uses of Radioactive Substances Co-58: Determine intake of vitamin B12 Fe-59: Determine the rate of formation of red blood cells. Sr-85: Used in bone scans Au-198: Used in liver scans Cs-137: Treatment of shallow tumors P-32: Treatment of skin cancers Sr-90: Treatment of eye disease

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