public dose

["Les Slaback, Health Physics" <SLABACK@micf.nist.gov>]

I tried to send this directly to S. Marsh at his stated address.
It was not accepted.
Since it is of possible interest to this list I am resending via this route.
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Public dose:

While 10CFR20 provides a method of demonstrating compliance by
assuming the external and internal components are split 50:50,
and using the Appendix B values to demonstrate compliance for the
internal dose component (and using a 50 mrem limit for the
external component), this method has several
disadvantages/complications.

1. The exposures are rarely split evenly, so this method adds up
to a factor of two additional conservatism.

2. Despite the statement in 20.1302 and in the preface to App. B
that App. B represents a public dose of 50 mrem, the values in
Appendix B are clearly based on 100 mrem (based on the stated
method of calculation).  This adds some uncertainty as to just
what the dose to the public is for your release.

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So (IMHO) the best approach is the direct
calculation/determination of the total public dose for
comparision against the 100 mrem public dose limit.
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Also, do not forget the need to meet the EPA 40CFR61 limit for
airborne releases.

SLABACK@MICF.NIST.GOV
   ...a little risk, like a bit of spice, adds flavor to life