Re: H-3 in desiccant (Drierite)?

[Schoenhofer <schoenho@via.at>]

At 11:21 05.02.1997 -0600, you wrote:

>A 0.2 ml sample of the original pump oil suspended in scintillation 
>cocktail read 1500 CPM.  The vacuum pump was rinsed with fresh oil 
>that was also analyzed.  The "rinse oil" had readings 
>indistinguishable from background.  

I imagine that the oil may be coloured and therefore exhibit quench. The
result "1500 CPM" does not allow any conclusions as to the activity
concentration (Bq/ml or pCi/ml). Tritium results are very sensitive to
quenching. I would recommend to use the good old internal standard method,
adding a known amount of tritium (with much higher specific activity) to the
sample you measured already, in order to determine efficiency and the real
activity concentration. Then you can decide how to dispose of the oil
without violating any prescriptions of maximum contaminant levels. 

>They plan to mix the two oil samples with one gallon of xylene and 
>dispose of it as flammable waste.  


>The Question is:  How can the desiccant be counted?  Drierite 
>consists of coarse morsels that change color when moisture is 
>absorbed.  Is it possible to get a valid reading when these morsels 
>are suspended in scintillation cocktail and counted?  

I do not know "Drierite", but you mentioned MgSO4. I would recommend to
dissolve a very small quantity in a few milliliters of distilled water and
mix it with a gel forming cocktail. You might have to test for mixing ratios
or follow the cocktail manufacturers instruction for aqueous solutions if
available. Again a second count with addition of a high specific activity
tritium spike will be necessary to determine the activity concentration. Be
careful! Tritiated water will evaporate from the desiccant and might
contaminate the surroundings. Keep the desiccant well closed.

If more information is necessary, contact me by e-mail or fax -43-1-495 53 08.

Franz
Schoenhofer
Habichergasse 31/7
A-1160 WIEN
AUSTRIA/EUROPE
Tel./Fax:	+43-1-4955308
Tel.:		+43-664-3380333
e-mail:		schoenho@via.at