AW: AW: Article: Radiation in Water Stumps Experts

["Franz Schoenhofer" <franz.schoenhofer@CHELLO.AT>]

    -----Ursprüngliche Nachricht-----

    Von: Bernard L. Cohen [mailto:blc+@pitt.edu]

    Gesendet: Mittwoch, 11. Februar 2004 06:12

    An: Franz Schoenhofer

    Cc: Barry E. Muller; John Jacobus; radsafe; know_nukes

    Betreff: Re: AW: Article: Radiation in Water Stumps Experts









    Franz Schoenhofer wrote:







            Barry,



            The only method I know about the determination of "gross alpha"

and "gross beta" is the evaporation of a water sample and measuring it with

some gas-flow low-level proportional counter, assigning the counts per

minute to some more or less (rather more) undefined "activities", which are

derived from "standards" of some more or less (rather more) arbitrary

selected radionuclides (Sr-90+Y-90, K-40 or similar for betas and "natural

uranium" or similar for alphas). These undefined values are corrected for

the source thickness, adding the final uncertainty.



           At least for radon, lliquid scintillation is an excellent way.

Add scintillant such as toluene or xylene and shake well, which transfers

the radon from the water into the scintillant. Put scintillant into a liquid

scintillation counter. .







            One thing is for sure in this procedure: The radon (and tritium

as well as any other volatile compound) will be removed. So changes in

"gross whatsoever" cannot be attributed to radon and your explanation cannot

be accepted.

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            Sorry to say, but your comment is not related at all to my

comment about gross-alpha and gross-beta, nor to my reasoning that in the

standard procedure radon will be removed and therefore the explanation given

by Barry cannot be valid and radon cannot be the reason for high

gross-whatsoever-values.



            Furthermore I would like to emphasize that I have measured

several thousand samples for radon in water and several tens of thousands of

samples for radon in air, using activated carbon. I have been active in

measuring water samples by liquid scintillation for compliance with

legislation for almost ten years. I gave a paper on that topic at the ACS

meeting last September in New York. So I dare say, that my comment is coming

from practice and not from hearsay.



            One more detail: Xylene and toluene are not scintillators, they

may serve as solvents for scintillators. Because of their chemical toxicity

these solvents are more or less "outlawed" and since more than 15 years

usually mineral oil based cocktails are used.



            Anybody interested in details is of course invited to contact me

for information at franz.schoenhofer@chello.at..



            Best regards,



            Franz