Re: Contaminated Lead Products Update

["Schoenhofer" <schoenho@via.at>]

Schoenhofer
Habichergasse 31/7
A-1160 Wien
AUSTRIA
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e-mail: schoenho@via.at

----------
> Von: Dwnarm@aol.com
> An: Multiple recipients of list <radsafe@romulus.ehs.uiuc.edu>
> Betreff: Re: Contaminated Lead Products Update
> Datum: Sonntag, 24. August 1997 21:11
> 
> The following is just an uneducated guess:
> 
> Assuming that the smelter byproduct material in question is a slag type
> material,  that this material actually forms on top of the melting
> feedstock,and there is no chemical separation of the U, Th or Ra during
the
> smelting process.
> 
> Is it then possible that the Radon eminating from the melting feedstock
gets
> trapped during the formation the slag material and that the high
> concentration of the Pb-210 is a result of the low slag to product ratio?
> 
> It seems to me that for the same reasons Radium is not present in the
Natural
> Gas filters or pigging materials while Pb-210 is that the same
explanation
> holds true here. That being the decay of essentially "trapped" Radon in
the
> slag.  Since the source of Radon is cut off upon slag removal, in a
couple of
> weeks all that remains in the slag is Pb-210.
>  ----------------------------------------------------------------------

The Pb-210 had millions of years to accumulate from decay of uranium via
radium in the lead ore. Pb-210 behaves the same way like stable lead and
follows therefore stables lead in the smelting process. If I remember
correctly Pb-210 has a half life of 22 years - this means that it would
take 22 years until half of the radon activity concentration would show up
as Pb-210 if there was a constant supply of Radon of course from the
equilibrium with radium. 

Concerning the high activity concentrations of Pb-210 in lead I do not
understand, why this is called "contamination". Under the term of
"contamination" one usually understands an activity which has been added to
some product. But in the case of Pb-210 it is present from the very
beginning in the ore. 

Franz