Re: Electronic Dosimeter Positioning

[Gv1@AOL.COM]

In a message dated 2/5/02 1:12:58 PM Central Standard Time, lglande@ENTERGY.COM writes:



> What positioning do you use for Electronic Dosimeters relative to PCs?  Is
>
> the dosimeter on a lanyard?  Do you place it inside or outside of the outer
>
> PC? Do you tape it?  Have you ever had a reported difficulty hearing an
>
> audible alarm due to dosimeter placement?  I am especially interested in
>
> responses from power reactor applications.


Being that you are from Entergy, I believe you have the DMC-2000 electronic dosimeter (ED).  I believe the most correct placement when in PC's is to clip the TLD and ED on the outside of the pocket.  This placement ensures the beta window on the TLD is not obstructed.  If the ED is clipped onto the pocket then the display is easy to read and the speaker is not obstructed.  I know the ED wears very well on a lanyard, so much so that you often forget to take it off.  We try to stay away from lanyards and PC's just because the ED swings forward when worker's lean over that hot valve.  Your more likely to contam the ED and record higher dose to the ED swinging forward in some cases.


Recently, some have gone to putting the ED and TLD in the pocket.  They get jumbled around, even get turned around backwards.  Even worse, the worker will clip the ED in the pocket backwards.  This will keep the ED clean, but you get an under-response and very likely not be able to hear the speaker in the real plant environment.  


I believe your utility uses also uses additional straps on the DMC-2000 to help hold them in place on the pocket.  The previous DMC models were larger with more robust clips such that they were less likely to become stripped off of a PC pocket.  If you tape the ED when clipped to the pocket, just make sure you don't cover the speaker.   A single inch wide strip of duct tape 8" long should handle the ED and TLD.  It seems that all of the current generation of ED's are pretty much beeper sized.  The shorter length of the new ED's also make them more likely to roll a PC pocket outwards when compared to their longer predecessors.


Regards to speaker sound and volume.  The speaker is essentially the same as that of the Siemens ED as well.  Both speakers need to be open to free air to prevent muting of their speakers.  I believe the similarity of the speakers between the two manufacturers is just do to size and power requirements.  Both ED's meet industry specs, but we just have to be smarter users.


Glen Vickers

Braidwood Nuclear Station