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Nuclear Fusion and Fission

  1. Sep 17, 2004 #1
    could anyone explian how do we get energy from the nuclear fusion and fission

    isnt that fission requires bindling energy which use up energy
  2. jcsd
  3. Sep 17, 2004 #2
    If you look at the graph of binding energy per nulceon against atomic number, you'll realize that elements around the position of iron have the highest binding energy. Fission occurs only in elements which have an atomic number much larger than iron(ie. uranium), and fusion occurs in elements with a smaller atomic number compared to iron(i.e. hydrogen). Both extract energy through converting part of their mass into energy.
  4. Sep 17, 2004 #3
    great thx, in my knowledge (correct me if i am wrong)

    fusion is when combines light nucleon or elements and realese of enrgy due to mass defec.

    Bindling energy is the energy needed to seperate all nucleons from nucleus.
    (now i try to describe fission in terms of bindlng energy and fusion)

    so when seperate each nucleon from the nucleus, energy is applied, but some nucleson re-jion after that , so fusion takes place and some mass is lost, therefore the energy must be realsed as well.

    did i got anything wrong?

  5. Sep 17, 2004 #4
    First fission occurs only in very heavy nuclei such as uranium, thorium, or plutonium. Although there is some spontaneous fission in both uranium and plutonium (not sure about thorium), most fission events occur when one of these nuclei absorbs a free neutron. When one of these nuclei fission, they generally split into two large fragments and they release some more neutrons. If you add up the masses of the fragments and the released neutrons, you will find that the total mass is less than the mass of the original nucleus and the neutron that initiated the fission. This mass defect is converted to energy in accordance with Einstein's famous relationship.

    So, no "refusion" occurs.
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