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Re: sodium iodide scintillation detectors
FYI
Rexell is Rexon at (216) 292-7373
http://www.rexon.com/
FB
----- Original Message -----
From: "Syd H. Levine" <syd.levine@MINDSPRING.COM>
To: <John_Sukosky@DOM.COM>; "Dave Oshlo" <doshlo@mgpi.com>
Cc: <radsafe@list.Vanderbilt.Edu>
Sent: Friday, August 06, 2004 3:28 PM
Subject: Re: sodium iodide scintillation detectors
> There is no excuse for a crystal failure due to the glue. Though more
> expensive, we use special ruggedized hermetically sealed crystals, usually
> in stainless steel, in well logging sondes. I have some of these built in
> the 1970's still working perfectly. If I were you, I would talk to other
> manufacturers than just St. Gobain (they own what was Harshaw / Bicron /
> Solon). There is an outfit in that same area called Rexell that is more
> responsive, and usually a bit cheaper. Also try Gintek in South Carolina,
> and a new outfit down near Huntsville (the name slips my mind).
>
> Syd H. Levine
> AnaLog Services, Inc.
> Phone: 270-276-5671
> Telefax: 270-276-5588
> E-mail: analog@logwell.com
> URL: www.logwell.com
>
> ----- Original Message -----
> From: <John_Sukosky@DOM.COM>
> To: "Dave Oshlo" <doshlo@mgpi.com>
> Cc: <radsafe@list.vanderbilt.edu>
> Sent: Friday, August 06, 2004 6:58 AM
> Subject: Re: sodium iodide scintillation detectors
>
>
> >
> >
> >
> >
> > Dave,
> >
> > Based on our experience with two 4 x 4 x 16 inch NaI detectors used in
our
> > standup whole body counter, the life expectancy is about 12 years. The
> > limiting factor is not the crystals themselves but the glue used to seal
> > the detector housing the NaI crystal. The glue starts to degrade after
> > about ten years allowing humidity to invade the crystal. When the glue
is
> > degrading and conditions are humid (e.g., summertime in Virginia), the
NaI
> > crystal absorbs water and you'll see a significant decrease in detector
> > efficiency. When conditions are dry (e.g. wintertime), the NaI crystal
> > will start to dry out and you'll see a corresponding increase in
detector
> > efficiency. The good news is that you can send your NaI detectors back
to
> > the manufacturer (e.g., St. Grobain) and they dry out the crystal and
> > reseal it into another detector housing. By doing this you can
> > indefinitely extend the life of your NaI detector. The drying out and
> > resealing process takes about a month for the large 4 x 4 x 16 NaI
> > detectors.
> >
> > I'm not sure what the shelf life of NaI detectors are in a warehouse.
> > However, it's likely to also be dependent on the glue that's used as a
> > sealant. Check with a crystal manufacturer such as St. Grobain to get a
> > definitive answer to this. Hopefully, the glue they're using today is
> > better than what they used 20 years ago.
> >
> > John M. Sukosky, CHP
> > Dominion
> > Surry Power Station
> > (757)-365-2594 (Tieline: 8-798-2594)
> >
> >
> >
> >
> > "Dave Oshlo"
> > <doshlo@mgpi.com> To:
> <radsafe@list.Vanderbilt.Edu>
> > Sent by: cc:
> > owner-radsafe@list.Van Subject: sodium
> iodide scintillation detectors
> > derbilt.Edu
> >
> >
> > 08/05/2004 02:46 PM
> > Please respond to
> > "Dave Oshlo"
> >
> >
> >
> >
> >
> >
> > Dear radsafers,
> >
> >
> > I’m looking for two pieces of data on a typical sodium iodide
> scintillation
> > detector but can find inadequate documentation.
> >
> >
> > 1. What is the life expectancy of a sodium iodide scintillation
> > detector in an operational nuclear power plant environment?
> >
> >
> > 2. What is the shelf life of a sodium iodide scintillation detector
> > (in the warehouse as a spare part)?
> >
> >
> > An exhaustive web search has not provided any solutions. If someone
could
> > point me in the right direction, I would be much obliged.
> >
> >
> > Thanks,
> >
> >
> > Dave Oshlo
> >
> >
> > MGP Instruments
> >
> >
> >
> >
> >
> >
> >
> > ************************************************************************
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> >
> >
>
>
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