Re: Multiple Dosimetry - ANSI N13.41 vs. Reg guide 8.34

[Wes Van Pelt <VanPeltW@IDT.NET>]

Lester.Slaback@nist.gov wrote:
> 
> There is not much interpretation involved.
> 10CFR20.1201 states that the assigned deep-dose and
> shallow-dose shall be based on the highest exposed
> portion of the body.  Hence no averaging or wieghted
> summing is allowed.
> 
> If there are other words from NRC that change this rule
> I hope someone will point them out.
> 
> Note that as a byproduct to this requirement the recorded
> doses are (or can be) very artificial.
> 
Les and Fellow Radsafers,

Yes, the NRC regulation 10 CFR 20.1201 says that you must record the
deep dose equivalent (DDE) for the highest exposed portion of the body.
(I believe this is aimed at the 50 rem/y non-stochastic dose limit.)

HOWEVER, read footnote 2 to the definition of Organ Dose Weighting
Factors, which says,

"For the purpose of weighting the external whole body dose (for adding
it to the internal dose) a single weighting factor, wr=1.0, has been
specified. The use of other weighting factors for external exposure will
be approved on a case-by-case basis until such time as specific guidance
is issued."

So, the NRC recognizes the issue of determining effective dose
equivalent for external radiation, and leaves an opening for those brave
licensees who wish to retreat from easy "conservative" assumptions.

Wes

-- 
Wesley R. Van Pelt, Ph.D., CIH, CHP                KF2LG
President, Van Pelt Associates, Inc.     
Consulting in radiological health and safety.
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