Re: lab equipment for drinking water testing

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

-----Ursprüngliche Nachricht-----

Von: Hudson, Scott A Mr CHPPMEUR <Scott.Hudson@CPE.AMEDD.ARMY.MIL>

An: 'radsafe@list.vanderbilt.edu' <radsafe@list.vanderbilt.edu>

Datum: Mittwoch, 11. Juli 2001 15:56

Betreff: lab equipment for drinking water testing





>Hello esteemed Radsafers:

>

>I'm posting a request for someone who works in one of our labs:

>

>What equipment are people using to count radionuclides in drinking water,

to

>comply with EPA requirements?  Brand names, software, suggestions and

>opinions are welcomed.  I expect mostly liquid scintillation systems, but

>descriptions of other techniques are invited, too.





Scott,



I do not have the new US regulations at hand, because I do my RADSAFE

activities from my computer at home, but I sure am not mistaken, that there

was not too much change from the previous ones and that it still is the

question of gross-radioactivity measurements and a gross-radium value as

well as uranium.



I have done drinking water surveillance in Austria for many years and we

measured thousands of samples. We used the "Quantulus", ultra low-level

liquid scintillation spectrometer, which due to its extremely low background

enabled us to use very simple methods, which I partially developed and which

cause extremely low costs for chemicals and personnel. For gross alpha+beta

activity we achieved by simply mixing 8 ml of sample with 12 ml of a

carefully selected cocktail an LLD of about 0.7 Bq/l. I give LLDs based on 3

sigma of the background and 500 min counting time. Any elevated activities

of betas or alphas can be detected by inspecting the spectra provided by the

spectrometer. Additionally we determined Ra-226 with another similarily

simple method and using alpha-beta discrimination, achieving an LLD of less

than 30 mBq/l. Recently I have worked out with a collegue a very simple

method for the simultaneous determination of Ra-226, Ra-224, Ra-228 and

Pb-210 by liquid scintillation spectrometry. I presented it last October at

the BAER-meeting in Seattle and a paper is in press in 'Radioactivity and

Radiochemistry'.



The methods we used work only with the "Quantulus" with its extremely low

background. The simplicity of the methods, the saving of costs for

chemicals, personell and time more than compensate the maybe somewhat higher

costs of the instrument compared with conventional equipment.



If you need more information, please do not hesitate to contact me.



Franz







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