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Homework Help: Fission reactor radioactivity

  1. Feb 14, 2012 #1
    Hello, I am asked to plot the activity of 137Cs in a 1Gw fission reactor over time of 100 years if the reactor is active from 0-20 years and shuts down at 20 years.

    So here are the facts:

    The reactor capacity is 1Gw
    Reactor is active for the first 20 years then shuts down
    At shutdown, all fission reactions stop and production of all radioactive fission fragments stop as well.
    * 6% of the fissions produce a 137 Cs fragment
    * There is no 137Cs in the reactor at the beginning of operation.

    So, if I'm given the progression of radioactive decay, I think I should be able to plot the activity of 137Cs.

    But, all I am given is the fact that the reactor is a 1Gw reactor.
    So I would need to know energy released per fission and what the radioactive source used is. Since this is not given in the problem, I believe it may be a standard.

    Does anybody know what radioactive isotope is used to power fission reactors? Also, how much energy is released per fission in such a case? Then if you can also tell me how the radioactive isotope we begin with decay to 137Cs, that would be wonderful.

    Thank you
  2. jcsd
  3. Feb 14, 2012 #2


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    Staff Emeritus
    Science Advisor

    You may want to try the Nuclear Engineering forum if you don't get any help here.
  4. Feb 14, 2012 #3


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    Staff: Mentor

    Actually, since this question is for schoolwork, I'm moving it to Homework Help / Advanced Physics.
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