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Homework Help: Nuclear physics problem (Chernobyl)

  1. May 22, 2008 #1

    I have a problem that i do not know how to solve.

    Activities from the fission products I(131) and I(133) were measured in the air of a city
    28/4-1986 at 17:00. The result was 0,12 Bq/m3 and 0,39Bq/m3 for I(131) and I(133), respectively. These isotopes came from the chernobyl nuclear reactor disaster.
    Use this information to calculate when the reactor container exploded. The relative amount
    of I(131) and I(133) produced in the fission of U(236) is 2,892 and 6,686 percent, respectively.

    I would appreciate it very much if someone could solve this problem.
  2. jcsd
  3. May 22, 2008 #2


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    Activity of a substance is equal to the product of the decay constant and atoms present, i.e. [itex]A\,=\,\lambda\,N[/itex].

    At the time of release the activity ratio of I-131:I-133 has a value related to their yields from the same mass of U-236. So A(131)/A(133) is proportional to 2,892/6,686.

    Simply write the Activity Ratio as a function of time from the accident and solve for the time.
  4. May 22, 2008 #3

    how do you solve it if the halflife for I(131) is given but Halflife for I(133) is unknown?
  5. May 22, 2008 #4


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    but you have the activity and the relative amount of I131 and I133 that was produced in the reactor.

    Try at last, we are not supposed to give full solutions or answers, we only kick people in the correct direction.

    This is a home work problem in the Nuclear and particle physics course @ uppsala university .. I hope for your own sake that you don't are asking us to do your hand in examinations.
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