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RE: Colorado Pocket Dosimeter Requirements
> We (a DOE contractor, responding to a requirement in the "old" DOE
> RadCon Manual) have had a similar procedure in place for several
> years. It requires that an investigation be done if results from
> pocket and/or electronic dosimeters vary from the primary dosimeter
> results by more than 50% and the primary dosimeter result is greater
> than 100 mrem. There is a "TLD Investigation" button on our access
> control entry system reports page that does the comparison for us.
> It then prints out all the monthly and quarterly results that meet the
> criteria.
Les,
Is this criteria standard within the DOE world? In the power reactor world, there is
generally an assessment when the difference is >25%. In cases where the doses
are < 100 mrem, most facilities perform an assessment where there is a difference
of 60 mrem.
I also believe that the primary reason why a pencil type dosimeter is usually higher
than the TLD is due to the errors associated with the primary influence quantities.
The TLD algorithm will accurately assess photon, low energy x-rays and high as
well as low energy beta. The TLD is going to respond accurately. The reason the
pencil dosimeter is usually higher is that there is rarely a dosimeter specific
calibration. The dose recorded is usually an eye-ball reading, and even when using
a reader, they often are not very accurate. The pencil dosimeter generally is very
poor in monitoring low energy x-rays and even most higher energy betas, will not
penetrate the wall.
All of the above ultimately led to the electronic dosimeter, which is much more
accurate, as long as they are calibrated to the energy and type of radiation of
interest.
------------------------------------------------------------------------
Sandy Perle Tel:(714) 545-0100 / (800) 548-5100
Director, Technical Extension 2306
ICN Worldwide Dosimetry Service Fax:(714) 668-3149
ICN Pharmaceuticals, Inc. E-Mail: sandyfl@earthlink.net
ICN Plaza, 3300 Hyland Avenue E-Mail: sperle@icnpharm.com
Costa Mesa, CA 92626
Personal Website: http://sandy-travels.com
ICN Worldwide Dosimetry Website: http://www.dosimetry.com
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