28.3

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28.3

  1. 1. 28.3 Fission and Fusion
  2. 2. Fission <ul><li>Fission is the splitting of nuclei into smaller nuclei </li></ul><ul><li>U-235 and Pu- 239 are examples </li></ul><ul><li>In the process, a tiny amount of mass is converted to energy- </li></ul>E=mc 2
  3. 3. Figure 19.4: Unstable nucleus.
  4. 4. Fission <ul><li>Notice for every one atom split 3 neutrons are released, which can split 3 more nuclei- this is called a chain reaction </li></ul>
  5. 5. Representation of a fission process.
  6. 6. Fission <ul><li>An atomic bomb is an uncontrolled fission reaction </li></ul><ul><li>A nuclear power plant has a controlled fission reaction- how is it controlled? </li></ul><ul><li>Well, the neutrons are absorbed so that the chain reaction is carefully regulated; and neutrons are slowed down so that they will react with the fissionable material ( usually U-235) </li></ul>
  7. 7. Reactor <ul><li>Moderator </li></ul><ul><li>Control rods </li></ul><ul><li>Coolant </li></ul><ul><li>Turbine </li></ul>
  8. 8. Diagram of a nuclear power plant.
  9. 9. Schematic of the reactor core.
  10. 10. Fusion <ul><li>Fusion is the combining of light nuclei into a heavier nuclei </li></ul><ul><li>4 1 1 H +2 -1 0 e ------- 4 2 He + energy </li></ul><ul><li>Energy comes from missing mass converted into energy ( E=mc 2 ) </li></ul><ul><li>Fusion releases much more energy than fission- but needs very high temp to get started </li></ul>
  11. 11. Fusion <ul><li>Occurs in the sun </li></ul><ul><li>On earth- in labs where matter can exist as plasma- not at point where reactors have been made. </li></ul>

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