Online Dose Rate Calculator?

Does anybody know of a good online dose rate calculator when considering shielding? For example: if I have a dose rate of 5R on one side of 1/2" lead what is the dose rate on the other side?

Thanks!

6 Replies

  • In reply to djrichards:

    Thanks djrichards.

    Does this seem correct? If I have a 20 R/Hr field, I need less than 1/4" of lead to have 100 mrem on the other side? This seems low. I deal with primary sides of SGs and they have 1/2" lead on the shield door that see much lower dose rate fields than 20R and have 250 mrem on the other side.

  • In reply to Cam Abernethy:

    Surprising myself with how much of this stuff I actually remember. Haven't worked in HP in a long time. :-)

    First of all, this is a point source calculation. Your situation is more of a plane source or line source.

    Secondly, if you have U235 in your channelhead, you have bigger problems than just the gamma dose rate. :-)

    Thirdly, U235 has a much lower energy and less prevalent gamma than you're dealing with. Depending on the plant's chemistry your primary isotope will be Co-60 or Iron 59 (Fe-59).

    Try the same calculation with one of those and you'll get a much different result.

    One other thing with regard to SG work. (I did a LOT of it.) Hopefully you aren't using just lead shielding directly over the SG opening or to shield the internal side of the diaphragm. Depending on the contamination levels, doing that can actually INCREASE your apparent gamma dose rate (actually a Bremsstrahlung X-ray) caused by "braking" the high energy Beta particles in there.

  • In reply to djrichards:

    I knew I was doing something wrong. Thanks for clearing that up.

    I think a lot of the industry steam generator shield doors are designed with as much shielding material (lead/aluminum or tungsten construction) as can be manually handled. They are taken for plant to plant and are not plant chemistry dependent.
  • In reply to Cam Abernethy:

    No worries. An easy thing to miss.

    I hope it helped.
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