Re:DOE Sites Reporting a less than number

[Franz Schoenhofer <schoenho@via.at>]

At 15:06 29.08.2000 -0500, you wrote:
>Other than for environmental monitoring programs, reporting of "less than"
>values is probably industry standard for radiological surveys.  

I respectfully disagree. I have worked for more than 25 years in
environmental and food monitoring. It was in my opinion a really necessary
practice, to determine the LLD of the method for a given counting time (we
used gamma-spectrometry and liquid scintillation spectrometry). The
counting time and other important factors were adjusted so that reasonable
LLD's could be achieved. Regarding the Cs-137 contamination after the
Chernobyl accident: For most food a MPC of 600 Bq/kg was (and still is) in
force. For checking compliance with regulations it is not necessary to
determine the mBq/kg, though it is not so difficult, you just would have to
chose a proper sample size and counting time. I always refused to go down
to this concentration range. 
For export and import purposes it was necessary to check for compliance,
which is: less than 600 Bq/kg. Internally we measured usually to an LLD of
less than 10 Bq/kg, which would satisfy even some of the environmentalists. 

For much different reasons it might be advisable to measure to lower levels
than just compliance and this is also mentioned for instance in European
Union directives, that the LLD's have to be at for instance 10 % of the
MPC. But even then, when the values (not) measured are lower, the values
are to be given as "less than". I know enough reports, excluding my owns,
about environmental surveillance, where over dozens of pages all values
given are "less than".  

So in principle, I do not understand why one should not give values as
"less than". The final question is the level, the value is "less than". If
the DOE inspectors do not like the expression "less than", then I think
they should give a reason why. Sure it cannot be that MPC's are simply not
considered, but that somebody would have to concentrate radionuclides from
tons of sludge or cubicmeters of water in order to obtain a values above
the LLD. If "nothing" can be detected, then it is below the LLD or DL,
(which has to be given in the result). You can never say that the value is
zero and you cannot attribute any value lower than the LLD - this would be
totally wrong in my opinion.

Regards,

Franz


Franz Schoenhofer
Habicherg. 31/7
A-1160 Vienna
Austria
Tel.: +43-1-495 53 08
Fax.: same number
mobile phone: +43-664-338 0 333
e-mail: schoenho@via.at


Please note my new telephone number at my office!

Office:
Ministerialrat Dr. Franz Schoenhofer
Federal Ministry of Agriculture, Forestry, Environment and Water Management
Radiation Protection Department (BMLFUW I/8 U)
Radetzkystr. 2
A-1031 Vienna
AUSTRIA

phone: -43-1-71100-4458
fax: -43-1-7122331

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