H-3 sampling

["Les Slaback, Health Physics" <SLABACK@micf.nist.gov>]

For most air sampling situations tritium is in the form of an oxide, so         
basically you are sampling tritiated water.  Given its low specific activity    
in the airborne water and given the difficulty of separating the tritiated      
water from normal water it is unlikely that there would be any significant      
sample lossesin any kind of tubing, tygon, teflon, or any other.  If there      
was such losses you would see a pretty soggy situation pretty quickly, and      
even then would presumably quickly reach an equilibrium situation.              
  On the other hand, it is not surprizing that you have observed contamination. 
Tritium tends to label surfaces and stick very well.  But this observation in   
itself does not prove or even strongly indicate significant sampling losses.    
                                                                                
If you are sampling tritium in a form where you do not have a significant       
chemical dilution, or that chemical form is highly reactive, then tubing        
choice might be an issue.  But even then it comes down to residence time,       
and the flow rate thru most sampling tubes tends to minimize this (at least     
for local sampling).  It might be an issue for an installed, building-wide      
monitoring system using 100's of feet of tubing if the chemical form is         
reactive, e.g., T+ or HT.                                                       
                                                                                
SLABACK@MICF.NIST.GOV  [NBSR Health Physics Group]                              
    ...a little risk, like a bit of spice, adds flavor to life                  
                                                                               
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