AW: PCM-2 turning off detectors by itself yet showing "green" light(operational)

["Franz Schoenhofer" <franz.schoenhofer@CHELLO.AT>]

What about a temporary and short power failure?



Franz





    -----Ursprüngliche Nachricht-----

    Von: owner-radsafe@list.vanderbilt.edu

[mailto:owner-radsafe@list.vanderbilt.edu]Im Auftrag von Pmink@bnfl-ettp.com

    Gesendet: Dienstag, 15. Juni 2004 18:05

    An: radsafe@list.vanderbilt.edu

    Betreff: PCM-2 turning off detectors by itself yet showing "green" light

(operational)







    Greetings!



    We had an interesting problem happen recently and I thought I would

check with the Radsafe community to see if anyone's had a similar problem.

A PCM-2 apparently disabled all 34 alpha and 34 beta channels by itself, yet

it still appeared to the workers that it was operational, i.e., had the

green light.  It would go through the motions of performing a personnel

survey and indicate that the person had nothing over the limits on them, but

all detectors were inactive.  The Instrumentation RCT found the PCM in this

disabled state when he went to perform a source check on it.  He then went

to pull the PCM log data at my request so we could determine the approximate

time frame this happened.  After pulling the data file (involves exiting the

PCM program to DOS), the RCT restarted the PCM program and the unit went

back to the state it was in prior to all channels being turned off.  We've

investigated this and have rule! d out operator error and sabotage.  The

high-level password required to access the menus to turn off the detectors

had just been changed and only three Instrumentation RCTs had it.



    BNFL had Thermo Eberline modify the PCM program last year so that a tech

couldn't accidentally turn off all the detector channels with a single

keystroke.  This accidentally happened last year when one of the field RCTs,

trying to help out, accidentally did this.  The menu options to turn off a

single detector channel and to turn off ALL detector channels are right next

to each other in the menu and the screens for each of them look exactly

alike, except one says "all detector channels."  The modification Thermo

made for BNFL requires that each detector channel has to be individually

turned off, so someone would have to send a lot of time to turn off a total

of 68 channels.  The last incident was issued as a "Lessons Learned" through

the DOE system, which warned that the PCMs will still show a green light

(i.e., appears to be operational) even if all detectors are off.



    Anyone seen anything similar to this?



    Thanks -



    Paul J. Mink, SAIC

    Lead Radiological Engineer/Technical Support

    BNFL-ETTP RADCON K-1550-T trailer

    Office (865) 576-2123

    Fax     (865) 241-0452

    Alpha pager 1-800-622-6576  (http://www.arch.com/message/)

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