In my earlier response I only answered the question asked. Another issue that may (or may not--the initial question did not discuss why the question was being asked) be relevant is what is the source of radon of concern. If the source is primarily general background, then the previous answer applies. If the concern is with a nearby significant source of increased radon releases, then "typical environmental" values for equilibrium may not be appropriate for use. In this case, additional considerations include whether the releases include the radon progeny or not, and how far from the source the receptor of concern is (time for ingrowth of progeny).
Duane.
Duane Schmidt, CHP
U.S. Nuclear Regulatory Commission
NMSS/DWM/DCB
dws2@nrc.gov
>>> Franz Schoenhofer <schoenho@via.at> 2/7/2000 2:54:22 PM >>>
At 12:14 07.02.2000 -0600, you wrote:
>Lew, Gert:
>
>NCRP Report 78 (section 6.3) provides an example of an "typical
environmental daughter activity ratio" of Rn-222/RaA/RaB/RaC equal to
1/0.9/0.7/0.7. If you converted to an equilibrium fraction, this would be
MUCH higher than 0.4.
0.4 is regarded as the mean equilibrium factor in indoor air.
Franz
<snip>
!
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