[ RadSafe ] Regulatory guidance re: piece of the Chicago Pile

[Carl Willis]

Hello RADSAFErs,

I recently acquired a piece of the Chicago Pile (CP-1; the first
nuclear reactor) from the wife of its original owner, Herbert L.
Anderson.  And it potentially poses some regulatory challenges here in
the USA that I feel I should address head-on in the interests of
owning the item responsibly and bringing it to an appreciative public
audience through museum loans and so forth.  I have already shared my
questions with our own Carl Sullivan at the New Mexico Radiation
Control Bureau via email, and await his response as well.

The artifact under consideration is a "live block" from CP-1 composed
of AGOT graphite milled with two holes in which are installed two
2.56-kg cylindrical fuel elements made of uranium metal. Photos and
HPGe gamma spectra are available over private email; I don't think
RADSAFE is able to handle attachments.  The graphite block is
displayed in an acrylic case (the original was popping apart and the
seams and I replaced it with modern solvent-welded acrylic).  It is
mounted on a felt-bottomed wood base with a descriptive brass plaque
announcing that the contents are "graphite and uranium used in the
first self-sustaining nuclear chain reaction."  Contact exposure rate
is about 7.5 mR / hr falling to about 3 mR / hr at four inches.  It
has been in the home of Herb and his wife from the time it was given
to Herb (posited to be the 10th anniversary of the CP-1 criticality,
although I am now somewhat in doubt of that timeline...read on) until
just this month, when it was given to me.

And here is the regulatory question for anyone qualified to opine: In
my initial assessment of the item's regulatory status I relied on
CP-1's known history of essentially zero-power operation over less
than three months to ASSUME that the two uranium fuel pieces
constituted an unimportant quantity of source material.  However, in
my subsequent measurement of gamma spectra with a germanium detector,
it is apparent that the dominant external radiation from the fuel is
from byproduct material, i.e. Cs-137, and that the approximate fuel
exposure amounts to some 100-200 kW-days per metric ton of
U--inconsistent with CP-1 itself by orders of magnitude.  The logical
explanation is that this fuel stringer was also used in CP-2 (the
rebuild of CP-1) before being turned into the commemorative item.
And, with that information in hand, I'm not sure I can make the
argument that the item falls under the unimportant source material
general-license provisions.  I should emphasize that my goals in
ownership of this unique historic artifact are to (A) take care of it
properly of course; and (B) facilitate its loan to various museums,
schools, or institutions where it may be appreciated by a curious and
inquisitive public.  So should I try to pursue a specific license for
it at the state level or via the NRC directly?  Should I still treat
it as unimportant source material?  Does its creation predate the
regulatory mandate of the NRC?  Should I just sit on it unless and
until someone belly-aches about it, and deal with any issues as they
may arise?

I am happy to discuss further; phone is 505-412-3277 or get in touch
with me via email.

Best regards
Carl Willis