RE: Fluorescent Lights in TLD Handling Room

["Walker, Scottie" <swwalke@sandia.gov>]

John:

I believe the problem with the teflon sensitivity was an initial quality
control problem for Harshaw (now Bicron/NE) and that it has largely been
eliminated.  We performed a test for light sensitivity back in 1995 and did
find some signal that was induced by both regular fluorescent lights as well
as direct sunlight.

We found that we could minimize the signal induced by keeping the cards
inside a container of some type (we use black plastic boxes) and by handling
the bare cards under yellow fluorescent lights.  The lights we use are GTE
Gold F40 GO 40 Watt.  We performed another test of the light sensitivity in
1998 and found that the problem had been reduced quite a bit, but that there
was still a small induced signal.  For a site where exposures are routine, I
doubt the signal would be enough to result in a positive dose.  However, for
our lab, where doses are not very prevalent and we have to deal with a large
environmental background signal, we chose to continue using the yellow
lights as a precautionary measure in the front part of our lab.  I don't
believe that Oak Ridge National Laboratory or Pacific Northwest National
Laboratory uses yellow lights in the processing facilities.

I haven't done any significant testing of the dosimeters that are placed
onto Kapton, but I can tell you that our batches seem very prone to sunlight
induced signals.

Hope this helps.

Scottie Walker
External Dosimetry Project Leader
Sandia National Laboratories
P. O. Box 5800 MS-0651
Albuquerque, NM 87185-0651
(505) 844-5241
swwalke@sandia.gov


> -----Original Message-----
> From: CHASE John -NUCLEAR 
> [mailto:john.chase@ontariopowergeneration.com]
> Sent: May 08, 2000 2:02 PM
> To: Multiple recipients of list
> Subject: Fluorescent Lights in TLD Handling Room
> 
> 
> We have a need to move the facility where we change out the 
> TLD cards in our
> TLD badges to a room with fluorescent lights. I need the 
> answer to some
> questions:
> 
> 1.	Does anyone know the right kind of fluorescent lights 
> to minimize
> the exposure of the TLD cards to UV (they are Harshaw cards 
> with TLD-700
> (LiF:Mg,Ti) chips in Teflon)?
> 2.	Does anyone know of North American suppliers for metric 
> (1160 mm) UV
> lights?
> 3.	What are people's experiences with UV lights for TLD-700?
> 
> Thanks in advance
> 
> John Chase
> Sr. Specialist, Dosimetry
> Radiological Protection Division
> Ontario Power Generation Nuclear
> (905) 430-2215, ext. 3242
> 
> john.chase@ontariopowergeneration.com
> <mailto:john.chase@ontariopowergeneration.com> 
> 
> 
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