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Homework Help: Equivalent dose rate question

  1. Sep 10, 2014 #1

    An unprotected radiation worker walks into a room which she knows is sometimes
    used to store high activity sources. She is unaware that, on that particular day, it
    contains an unshielded Co-60 γ source. The source is encapsulated in a material which
    filters out β emissions, but with negligible reduction to the γ emissions. The activity
    of the source is 2.0 × 104
    MBq. Each decay releases two γ photons with individual
    energies 1.17 MeV and 1.33 MeV - a total photon energy E = 2.50 MeV per decay.
    She is standing 6.0 m from the source. Assume the source is approximately a point
    (a) Calculate the equivalent dose rate (in µSv/h) delivered to the position of the

    2. Relevant equations

    I don't know which equation to use

    3. The attempt at a solution

    I didn't understand how to do the question but I checked the answers and I don't understand how they did this:

    H [µSv/h] = 0.14 × 2 ×104 ( MBq) ×(2.50 MeV)/ (6 m)^2
    =194 µSv / h
    ≈190 µSv / h

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Sep 11, 2014 #2


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    Staff: Mentor

    This is just [factor that takes units and absorption probability into account] * [activity of the source] * [released energy per decay] / [distance squared]. You should find this formula in your book/script/... Which part is unclear?

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