Inhalation class default for ICRP 30 -Reply

[Duane Schmidt <DWS2@nrc.gov>]

Drew Thatcher asked about default inhalation classes (D, W, Y) to use in a
pathways analysis dose assessment.

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Is there a source or reference for default absorption types that would 
apply to ICRP 30?  My primary interest is for U and Pu isotopes where the 
differences in DCFs between absorption types has an impact on my results. 
 Any/all assistance would be appreciated.

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One simple answer is that if the analysis you are performing is a screening-level
assessment, you may wish to use the solubility class that is most conservative
(highest estimated dose). 

You indicated that the assumed class has an impact on the results. If this impact is
significant to some decision you might make, this is an indication that you may want
to do more work to determine the solubility class of the actual material with which
you are dealing. This sounds like a sensitivity analysis, so a related question is: is
this parameter (solubility class) the one to which the results are most sensitive? If
not, it may help to focus on other, more sensitive parameters first. Of course there
are cost-benefit considerations on deciding which parameters to evaluate for more
site-specific values.

Hope this helps.

Duane Schmidt
U.S. Nuclear Regulatory Commission