wrong DoT label, contact dose rate

[Lester Slaback <Lester.Slaback@NIST.GOV>]

While the rules use a 'contact' dose rate reading to classify a pkg for
labeling that measurement is not explicitly defined.  The NRC Reg Guide for
making distance corrections to extract a hypothetical surface dose rate
from any measuement was explicitly withdrawn long ago.

The purpose of the rule is to provide information on dose to folks who pick
up pkgs and hold them in close proximity to their body.  From that point of
view the measurement process (in terms of a large or small detector) is not
very critical.  Note that it is not an issue of skin dose or extremity
dose.  The limits for those modes of exposure are sufficiently less
restrictive than the whole body limit that they are not an issue.

As pointed out the results of a contact reading can be highly variable
depending on the source geometry and detector type.  In fact it is so
variable that one wonders at the usefulness of the limit.  Further the
existence of the variability creates the regulatory hair-splitting issues
raised by results slightly above the limit.  It seems a bit silly to have a
regulatory criterion on which you might be cited for being 20% over (e.g.,
0.6 instead of 0.5) when the measurement process can be variable by 200%
(or more).

Please be reminded: DoT is asking for comments on the transportation rules,
and specifically on IAEA ST-1, in anticipation of the next round of
revisions.  If you do not comment you cannot complain about the idiocy of
certain rules (well you can, but you should be ignored).

Disclaimer:  the above are the personal musings of the author, and do not
represent any past, present, or future position of NIST, the U.S. government,
or anyone else who might think that they are in a position of authority. 
Lester Slaback, Jr.  [Lester.Slaback@NIST.GOV] 
NBSR Health Physics 
Center for Neutron Research 
NIST
100 Bureau Dr.  STOP 3543 
Gaithersburg, MD  20899-3543 
301 975-5810 voice
301 921-9847 fax
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