Physics 2-nuclear fission and fusion

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  • Created by: Bea.pal
  • Created on: 28-03-16 22:49
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  • Nuclear Fission is the splitting of big atomic nuclei.
    • Nuclear power stations generate electricity using nuclear reactors.
      • In a nuclear reactor a controlled chain reaction  takes place in which atomic nuclei split up and release energy in the form of heat.
        • This heat is simply used to heat water to make steam, which is used to drive a steam turbine connected to an electricity generator.
          • The fuel that splits up is usually uranium-235 or plutonium-239 or both.
    • Physics-Nuclear Fission and Fusion
      • The chain reactions
        • 1.)For a nuclear fission to happen, a sow moving neutron must be absorbed into a uranium or plutonium nucleus.the addition of a neutron makes the nucleus unstable, causing it to split.
          • 2.)Each time a uranium or plutonium nucleus splits up, it spits out 2 or 3 neutrons, one of which might hit another nucleus causing it to split also, keeping the chain reaction going.
            • 3.)When a large atom splits in two it will form 2 smaller nuclei. These two nuclei are usually radioactive because they have the wrong number of neutrons in them.
              • 4.)A nucleus splitting(called a fission)gives out a lot of energy-lots more than you get from any chemical reaction. Nuclear processes release much more energy than chemical processes do. That's why nuclear bombs are so much more powerful than normal bombs which rely on chemical reactions.
                • 5.)The main problem with nuclear power is with disposal of waste. The products left over after nuclear fission are highly radioactive, so they cant just be thrown away. They're difficult and expensive to dissolve of safely.
                  • 6.)Nuclear fuel is cheap but the overall cost of nuclear power is high due to the cost of the power plant and final decommissioning. Dismantling a nuclear power plant takes decades.
                    • Nuclear power also carries the risk of radiation leaks from a plant or a major catastrophe like chernobyl.
      • Nuclear Fusion-the joining of small atomic nuclei.
        • 1.)2 light nuclei like hydrogen for example can join to create a larger nucleus-this is called nuclear fusion.
          • 2.)Fusion releases lots of energy-more than fission for a given mass all energy released in stars comes from fusion so people are trying to develop fusion reactors to generate electricity.
            • 3.)Fusion doesn't leave behind much radioactive waste like fission and there is plenty of hydrogen knocking about to use as fuel.
              • 4.)The big problem is that fusion can only happen at really high temperatures-about 10 000 000 degrees C!
                • 5.)You cant hold the hydrogen at the high temperatures and pressures required for fusion in an ordinary container-you need an extremely strong magnetic field.
                  • 6.)There are a few experimental reactors around,but none of them are generating electricity yet. At the moment it takes more power to get up to temperature than the reactor can produce.
  • The chain reactions
    • 1.)For a nuclear fission to happen, a sow moving neutron must be absorbed into a uranium or plutonium nucleus.the addition of a neutron makes the nucleus unstable, causing it to split.
      • 2.)Each time a uranium or plutonium nucleus splits up, it spits out 2 or 3 neutrons, one of which might hit another nucleus causing it to split also, keeping the chain reaction going.
        • 3.)When a large atom splits in two it will form 2 smaller nuclei. These two nuclei are usually radioactive because they have the wrong number of neutrons in them.
          • 4.)A nucleus splitting(called a fission)gives out a lot of energy-lots more than you get from any chemical reaction. Nuclear processes release much more energy than chemical processes do. That's why nuclear bombs are so much more powerful than normal bombs which rely on chemical reactions.
            • 5.)The main problem with nuclear power is with disposal of waste. The products left over after nuclear fission are highly radioactive, so they cant just be thrown away. They're difficult and expensive to dissolve of safely.
              • 6.)Nuclear fuel is cheap but the overall cost of nuclear power is high due to the cost of the power plant and final decommissioning. Dismantling a nuclear power plant takes decades.
                • Nuclear power also carries the risk of radiation leaks from a plant or a major catastrophe like chernobyl.

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