Air Sample Channeling

["ERIC GOLDIN"<goldinem@songs.sce.com>]

     Regarding the "channeling" of radioiodine:  consideration of 
     "channeling" in radioiodine charcoal cartridges was recommended 
     in NRC Regulatory Guide 4.8, 1975, guidance for environmental 
     technical specifications (essentially effluent and environmental 
     monitoring programs for nuclear plants).  Factors such as 
     cartridge packing density, pore size, sampling flow rate, 
     velocity and particle size and chemical makeup all need to be 
     considered, but our experience has been that using standard 
     conditions and quality commercially procured cartridges, we've 
     never seen any channeling.  One thing to look for is vibration 
     induced channeling due to the sample pump.
     
     Eric Goldin
     <goldinem@songs.sce.com>

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