[ RadSafe ] Low background Shielding Material

Fri Jun 9 10:36:33 CDT 2006

This is the story as I recall also.  I had actually found this discussed in
one of the older NCRU or ICRU reports many years ago, but am not sure if I
can put my hands on the reference again.  I'll check my old notes at home
and let you know.

By the way, the reason I found out about this was that I was once doing
background measurements with an early portable HPGe detector in the WIPP
mine, long before it went hot (around 1982).  The background was very low,
but I kept finding small CO-60 peaks in the spectrum that couldn't be
explained (they wouldn't have been detectable in a normal background area).
Turned out it was probably the steel tripod that I had mounted the system
on.

Doug Minnema, PhD, CHP
National Nuclear Security Administration, US DOE

-----Original Message-----
From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl]On
Behalf Of john.gumnick at exeloncorp.com
Sent: Thursday, June 08, 2006 6:44 PM
To: radsafe at radlab.nl
Subject: RE: [ RadSafe ] Low background Shielding Material

Cobalt-60 is used as a wear detector in blast furnace applications. Small
Co-60 sources are embeded in the firebrick furnace lining at a known
distance from the hotface. These are readily detectable from the outside of
the furnace. When the liner has worn to a certain point the source
disappears into the melt and is no longer detectable from the outside. A
typical furnace might have 50 sources in the 1-5 mCi range embeded at
various distances from the hotface, and a quick survey will tell you whether
they're still in place or not. This technology has been used since the
isotope became available for industrial applications, at least since the
'50s.

John Gumnick, CHP
Exelon Nuclear
Corporate RP Technical Manager
630-657-2700

-----Original Message-----
From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl]On
Behalf Of John R Johnson
Sent: Thursday, June 08, 2006 4:27 PM
To: chemitech at chemitech.com; radsafe at radlab.nl
Subject: RE: [ RadSafe ] Low background Shielding Material

Radsafers

Information on fallout is available in the UNSCREAR reports. They are at
http://www.unscear.org/unscear/en/publications.html

 _________________
John R Johnson, Ph.D.
*****
President, IDIAS, Inc
4535 West 9-Th Ave
Vancouver B. C.
V6R 2E2
(604) 222-9840
idias at interchange.ubc.ca

-----Original Message-----
From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl]On
Behalf Of Marco Caceci
Sent: June 8, 2006 1:40 PM
To: radsafe at radlab.nl
Subject: RE: [ RadSafe ] Low background Shielding Material

I remember reading they find fallout Ru (Ru-106?) in new steel (from rain)
and of course Co60 etc. in recycled stuff. Sorry, no references, but it
makes sense.

Marco

-----Mensaje original-----
De: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] En nombre
de Vernig, Peter G.
Enviado el: jueves, 08 de junio de 2006 17:09
Para: radsafe at radlab.nl
Asunto: [ RadSafe ] Low background Shielding Material

Group,

I have heard many times that "Pre World War II battleship steel" is used for
extremely low background shielding.  I had always wondered about that as it
seemed that an infinitesimal amount of fallout would find its way into
steel.  But then I heard another explanation that made more sense something
to do with the fabrication process that apparently changed post WWII and
involved a small amount of Co-60 I think.

Does anybody out there know what the explanation is?

Any opinions in this e-mail are solely those of the author, and are not
represented as those of the VA Eastern Colorado HCS, the Dept. of Veterans
Affairs, or the US Government.

Peter G. Vernig, Radiation Safety Officer, MS-115, VA Eastern Colorado
Health Care System, 1055 Clermont St. Denver, CO 80220, peter.vernig at va.gov,
Phone= 303.399.8020 x2447; Fax = 303.393.5026, alternate fax, 303.393.5248

"...whatever is true, whatever is noble, whatever is lovely, whatever is
admirable, if anything is found to be excellent or praiseworthy, let your
mind dwell on these things."

Paul of Tarsus

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