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Re: Field Detection of Pu -Reply

Ditto on the FIDLER.  We used a Ludlum
2221 CaF2 crystal and the Bicron NaI at
Johnston Atoll screening coral sands for
WGP.  I believe on the 2221 you can
switch from the 17-keV photon from Pu
to the 59.5- (or 60-) keV photon from the
ingrowth of Am-241.  This worked very
well.  We also setup two FIDLERs
side-by-side to cover the swath of the
conveyor belt to screen for Pu.  This
worked well also.

David Harrison
DOE Los Alamos Area Office
528 35th Street
Los Alamos, NM 87544

>>> Craig Reed <jreed@utk.edu>
04/23/98 05:55pm >>>
The absence of beta in the presence if
significant alpha would certainly be an
indicator of potential HEU/Pu. 
Unfortunately, I wouldn't want to open the
alpha source "dry" enough to make that
assessment possible.  A fidler probe (i.e.,
thin crystal for seeing low energy photons)
with a multichannel analyzer might be of
use with practice.  Might want to borrow a
Fidler probe from someone to see what the
"background" spectrum will allow in the
way of MDA's for the non-DU

Craig Reed
Legacy Waste

Bates Estabrooks wrote:

>           RADSAFERs:
>           Maybe some of you all could offer
a suggestion.
>           Rocky Flats will, in a few weeks,
begin excavating a
>           1950s-vintage trench in which
drums of depleted uranium chips
>           and turnings (mixed with cutting
coolants)  were buried.
>           As each intact drum (highly
unlikely), or its carcass with
>           contents (very likely), is excavated,
we would like to know
>           rather promptly whether we have
any "surprises" such as Pu or
>           highly-enriched uranium.  We
know that large quantities of DU
>           are buried there, but since the
facility also worked with Pu
>           and HEU, there is a small chance
of these things being found
>           also.
>           Therefore, can anyone recommend
a quick screen using field
>           instruments that we might be able
to perform on each backhoe
>           bucket of stuff to indicate whether
either of these fissile
>           substances (pu or HEU) are
present in significant quantities?
>           We have a fairly broad range of
portables including the SAIC
>           AP-2.
>           Thanks for your help.
>           Bates Estabrooks
>           bates.estabrooks@rfets.gov
>           303-966-3769