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Radiation Dose rate

  1. Mar 6, 2016 #1
    If someone was splashed with 5 ml of reactor pool water over 10 cm^2 of there skin, how much dose they will receive?
    note: the tritium was created in the reactor pool water.

    Also if they swallowed 125 ml of pool water how much dose they will receive ?

    Thanks.
     
    Last edited: Mar 6, 2016
  2. jcsd
  3. Mar 6, 2016 #2

    mfb

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    That is impossible to tell without many more details, and an analysis by an expert.
    You didn't even specify the reactor type (and no, adding this single information does not help).
     
  4. Mar 6, 2016 #3

    Astronuc

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    Insufficient information. One would need to determine the concentration of T in the water as one input. The pool water would not be 100% tritium, but could be in the ppm range.

    Exposure to the skin is considered external, while exposure from within (by inhaling or ingestion, i.e., swallowing/eating) is considered internal. On the surface of the skin, one would absorb about half of the radiation, while internally, one would absorb all the radiation, and since elements have both radioactive and biological half-lives, the internal exposure may be mitigated by excretion.
     
    Last edited: Mar 6, 2016
  5. Mar 7, 2016 #4

    mfb

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    Tritium beta radiation is very soft, so it won't get deep into the skin (and the exposure time is very short). The skin will absorb some part of the water, however, and that leads to a radiation dose. I guess you can reduce that part a bit if you put your hand into normal water quickly afterwards, to dilute the water with a higher tritium content.
     
  6. Mar 7, 2016 #5
    For skin contact there would be little if any penetration of the beta particles through the first layer of skin which is mostly dead and of course is easily removed . As noted above the concentration in pool water can be highly variable You can get an estimate of the safe limit for ingestion. The US limit for ingestion of Tritium by the general public is 740 Bq/L which is only 4% of the MPD (100 uSv). Presumably a person falling into a reactor pool would be a radiation worker whose MPD would be at least 50 times greater. So if they only swallowed 125 mL and and you allow for the fact that the internal radiation dose will only be due to this dose then the max concentration in the water could be (50)x(8)x(1/0.04)x(470 Bq/L = 2.9 MBq/L.

    However I would bee concerned about other radionuclides in the water like Cs-137 (1.18 MeV beta) and I-131(0.806 MeV beta) both much more radiotoxic compared to Tritium.
     
  7. Mar 16, 2016 #6
    Reactor pool water contamination varies due to factors such as: history of fuel pin failures, reactor type (BWR/PWR), and the effectiveness of the cleanup system (ion exchange and filter processes). I have had minor skin contaminations from contact with small droplets of water during refueling. However, at the Barseback plant in Sweden we put our bare hands into the pool with no skin contamination. The reactor is a BWR with an all-stainless loop, which is expensive and unusual. They also have a history of few fuel pin failures. We were jokingly told that we were contaminating the reactor with sodium and such from our skin.
     
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