RE: Firefighters and Dosemetry in the UK.

[wln@inel.gov (Wilbur l Nees)]

We've started using EPDs with INEEL firefighters this year.  So far they have not had to use them in an actual accident situation.  The fire department seems quite happy with them so far.  The approach that I favor is wearing the EPD outside of the bunker gear and the TLD inside.  This would be the most conservative approach.  Having the EPD alarm early, but have the TLD shielded by the clothing the firefighter are wearing to measure the actual dose.  We use two different calibartion points for the EPDs at the INEEL, with the EPDs using different color face plates for the low and high energy calibration points.  The fire department uses the high energy calibrated EPD.  Fortunately, the regular  firefighter's bunker gear does a fair job of shielding the low energy photons.  It should be noted that the pocket dosimeters that were used earlier had these same issues involved in their use.

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From: 	Sandy Perle[SMTP:sandyfl@ix.netcom.com]
Sent: 	Saturday, February 15, 1997 11:53 AM
To: 	Multiple recipients of list
Subject: 	Re: Firefighters and Dosemetry in the UK.

Problems with Electronic Personnel Dosimetry are directly related to 
the concers Neil raised, i.e., energy dependence which is highly 
affected by the EPD itself. The problem is enhanced when additional 
attenuation is provided over the dosimetry. Generally speaking, in a 
nuclear power plant, during normal opertaion, the EPD is not a 
problem, if the EPD is correctly calibrated againast a known source 
and energy. However, the EPD falls way short when in a low-energy 
photon environment. I would suspect that radiopharmaceutical 
shipmens, and any incident encountered would be one where the 
individual would be exposed to the low-energy photons. Therefore, the 
individual wearing the EPD needs to have additional correction 
factors available to apply to the readings, after the fact, to gain a 
better knowledge of what the true exsposure rate was, and the 
cummulative exposure for the time period.

EPDs are highly energy dependent, and depending on which EPD is used, 
the battery pack seriously affects the readings of the instrument. 

The alarm in some cases will not function properly, and in cases 
where it does, the alarm more likely than not, will not be heard. I 
suggest that if you are concerned with the alarm, which I know you 
are, then a vibrator function needs to be added to the alarm. The 
critical point to be made is at what kevel do you want the alarm to 
sound (vibrate)? You need to consider both the rate and cummulative 
exposure.

Contamination would be a serious problem, for it will adversely 
affect the instrument .. for the entire period and beyond.

I am not familiar with many firefighting groups using the EPD in this 
country, yet. I'd be interested in hearing about any who do and the 
problems that they encounter.

A very good topic for discussion....

------------------
Sandy Perle
Technical Director
ICN Dosimetry Division
Costa Mesa, CA 92626
Office: (800) 548-5100 x2306 
Fax:    (714) 668-3149
  
mailto:sandyfl@ix.netcom.com
mailto:sperle@icnpharm.com

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