Re: Area Postings for Beta

[William V Lipton <liptonw@dteenergy.com>]

The definition of "radiation level" in 49 CFR 173.403 is:  "the radiation
dose-equivalent rate expressed in millisievert(s) per  hour or mSv/h
(millirem(s) per hour or mrem/h).  Neutron flux densities may be converted into
radiation levels according to Table 1 ..."  (DOT has gone metric; it's a pain in
the ****, but, fortunately does not affect too many people other than the
shippers and carriers.  The RP Techs report the survey results in traditional
units, and we make the conversions as necessary.)  I take this to include beta
dose rate.  This would generally only apply to the surface dose rate.  It's
especially important when evaluating an exclusive use vehicle for free release,
since there is a fixed contamination limit - see 49 CFR 173.443(c):  "... A
vehicle may not be returned to service until the radiation dose rate at each
accessible surface is 0.005 mSv per hour (0.5 mrem per hour) or less ..."  This
should definitely include any beta component of the dose rate.

The opinions expressed are strictly mine.
It's not about dose, it's about trust.

Bill Lipton
liptonw@dteenergy.com

Robert Denne wrote:

> Anyone know of a similar reference for DOT?  I've always labeled and shipped
> based on the sum of all radiations involved.  This is particularly necessary
> in the case of shipping spent nuclear fuels (which of course not many of you
> are doing).  Also, the limits expressed in 49CFR173.443 (c) and (d) for
> returning vehicles back to service could be greatly affected by beta dose
> rates if used.  (I have always considered beta when meeting these limits.)
>
> As a note to plant posting, I have also posted some areas around
> penetrations based on a sum of neutron and gamma.
>
> Bob Denne
> ATG, Richland

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