RE: False alarms on DMC model 90 electronic dosimeters

["LANNI, MARC" <MLANNI@entergy.com>]

John,

  Any power loss on the histogram?  Had the same problem attributed
to an electronics glitch in the DMC2000's. Don't know if the same 
problem occurs in 90's. Basically the dosimeter saw a power loss, then
gave an incredible dose rate and dose. This dose also did not get erased
from the eprom so the next worker to use the dosimeter recieved the
same dose. We found it with the histograms.

     Marc

-----Original Message-----
From: Leamon, John A. [mailto:jaleamon@tva.gov]
Sent: Wednesday, October 06, 1999 7:37 PM
To: Multiple recipients of list
Subject: False alarms on DMC model 90 electronic dosimeters


Does anyone out there, especially those of you working at a plant site, have
practical experience dealing with false alarms on Merlin Gerin Model 90
electronic dosimeters.  We are using these dosimeters with the Merlin Gerin
LDM101 reader with 549C firmware and Windows 95 based HIS20 Access Control
software.  

Several times each day, a small percentage of workers are exiting the RCA
where known and confirmed radiation levels are less than 5 mrem/hour but the
ED indicates a much, much higher value (sometimes in the hundreds or
thousands of mrem/hour).  Needless to say, this is quite disturbing to the
Rad workers, the Radcon staff, and other interested parties.  

We have been struggling with this issue for a month without success.  Any
good ideas are appreciated to help get this behind opportunity behind us and
move on to more worthwhile efforts.

Contact me, John A. Leamon, at 423-751-7038 or email at jaleamon@tva.gov

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