I'd like to suggest caution on publishing a ion chamber beta activity 
correction factor.  It is very energy dependent as well as geometry dependent.

In my opinion, if you need a factor, It is better to determine it for the 
particular occasion.  A correlation can be determined by measuring some 
activity near the upper end of a frisker then counting it on an ion-chamber.  
This should get you a reasonably close conversion factor that is appropriate 
for the beta energies being measured.

David Brehm
Fort Calhoun Nuclear Station
Supervisor - Radiological Equipment & Dosimetry
Office: 402.533.7582
Cellular: 402.214.0107
Pager: 402.561.3310

From: [email protected] [mailto:[email protected]] On Behalf Of 
[email protected]
Sent: Saturday, November 06, 2010 6:33 AM
To: [email protected]
Subject: Powernet: Ion chamber reading to dpm conversion

With respect to determining contamination levels using an ion chamber 
instrument, there appears to be two schools of thought:

 1.  The ion chamber open window reading in mR/h is converted to dpm according 
to the following relation ship:
1 mR/h = 50 kdpm
 2.  The difference of open window minus closed window is multiplied by the BCF 
and the result is converted to dpm according to the relationship:
1 mR/h = 50 kdpm
What method do you use and do you have (or know of) a reference for your method?
Thanks in advance,

Jeffrey J. Cady, CHP, RPT
Mgr RP Technical Support
Exelon Nuclear
Dresden Station
Phone: (815) 416-2719
[email protected]


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