Re: Job coverage for contaminated filters

[BRZGV@ccmail.ceco.com]

     I have heard references to Be-7 as being produced by spallation 
     interactions in the atmosphere and therefore being "naturally 
     occurring".  It is postulated that the only reason this usually shows 
     up in large Mega-cfm samples is due to the small amounts produced.  
     I've seen large outside-air intake filters show up with activity 
     amounts that could only be seen with GeLi count systems with 15 to 30 
     minute count times and activities around 10E-10 microCi or less for a 
     450 ml sample of torn up filter media.
     
     I work at a nuclear power station, so we have a few other isotopes to 
     worry about.  If Be-7 were to show up with the usual Pb, Ac, Bi, with 
     the absence of activation or fission products, it would be classified 
     as only possessing naturally occurring nuclides and not subject to any 
     radiological control.
     
     What type of facility do you have?  What type of sources and what do 
     you credit as the source of Be-7?
     
     
     Glen Vickers
     HP, Nuclear Power Generation
     BRZGV@ccmail.ceco.com
     815-458-2801 ext. 2792
     
     Usual disclaimer...Any comments out there?


______________________________ Reply Separator _________________________________
Subject: Job coverage for contaminated filters
Author:  radsafe@romulus.ehs.uiuc.edu at INTERNET
Date:    4/2/96 12:31 PM


OK experts, please provide any nifty ideas and solutions to the following 
hypothetical problem.
     
Provide contamination control for changing filters on an air handling system 
which tends to build up Be-7 in the filters.  These are regular 24"x24" 
'boulder catcher' pleated paper filters.  There is a bank of about 16 of 
them.  The air handler just recirculates the air through the filters, a 
cooling coil, and back out into the space.
     
Now for the fun part - the air handler is ~ 60' up in the air at the top of 
a dome shaped "hall".  There is no catwalk.  An aerial "manlift" is used to 
access the area (it sways a lot).
     
What's the cheapest, easiest way to deal with this?  Anyone familiar with 
rolling prefilters, special containments, or anything we could adapt to the 
device itself?  Is there a reasonable substitute for a catwalk? (the main 
hazard of the job is the aerial lift)
     
Lastly, how do I check people and items for Be-7 contamination at the 
rediculously low limit of 1000dpm/100cm^2  IN THE FIELD.  (a pancake GM sees 
this nuclide at around 100 cpm per 15,000 dpm)
     
Did I mention, this is just a hypothetical case?
     
     
My employer did not review or approve this. 
Keith Welch
CEBAF
welch@cebaf.gov
KW