Schedule B (10 CFR 30.71) Activity Values -- How Were They Calculated/Derived

[David W Lee <lee_david_w@lanl.gov>]

Dear Radsafers:

        As in the past, hopefully some of the NRC experts on the Radsafe net
may be able to provide a definitive answer to the questions posed below:

        Title 10 CFR 30.71 is a listing of various byproduct material
isotopes by listed threshold activity in microcuries above which one must
get an NRC license to possess that particular radionuclide in
sealed/unsealed form, and below which one does not need an NRC/Agreement
State license.

        While this Table includes such low-energy emitting nuclides as H-3
and Fe-55, the vast majority of the listed nuclides emit penetrating
radiation.  More curiously, however, as Radsafers Keith Brown and Wes Dunn
have pointed out, only one alpha-emitting (nonpenetrating
radiation-emitting) nuclide is listed, Po-210.  My present focus concerns
Po-210 in the sense that I am running out of intuition in trying to discern
why the licensing threshold activity for this nuclide is such a paltry 0.1
microcuries.  

        The footnote at the end of Schedule B lists three Federal Register
citations.  I have found all three of these citations on microfiche in our
local research library.  These FRs merely make additions/corrections to the
Schedule B, itself; none contain any explanation as to how the activity
threshold values were originally calculated/derived, unlike the footnotes of
10 CFR 20, Appendix B and C.

        Are there any 'old timers' out there in Radsafe land who remember
where these values came from or who can point to a reference wherein the
calculation of these values is described?  How old are these values anyway?

Thank-you.

David Lee
(505) 667-8085
(505) 667-9726 (FAX)       
David W. Lee
Radiation Protection Policy
& Programs Analysis Group (ESH-12)
Los Alamos National Laboratory
PO Box 1663, MS K483
Los Alamos, NM  87545
Ph:  (505) 667-8085
FAX: (505) 667-9726