Re: Respect

[Franz Schoenhofer <schoenho@via.at>]

Dear Diana,

I read with some surprise your recent mail and after having read, that you
know everything about this topic, all the shortcomings and that you are
aware that the answer to your original question can be found in textbooks I
am even more surprised, why you posted your question. I have offered you to
give you information on possible tricky questions, but in spite of your
mail I  still do not think that RADSAFE is a forum for really basic
questions, which should be covered by basic training. Looking up a textbook
is in my opinion not an extensive research.

I am concerned with the attitude to measure radionuclides, which are
difficult to measure because they are alpha- and/or beta emitters with the
most simple equipment. If it has to be done, then the appropriate equipment
and the appropriately trained personell has to be provided. If both
equipment and personell cannot be provided then the measurements cannot be
done - it is that simple. 

As to your original question:

I understand from your last mail that the LUDLUM 3 is a GM pancake
detector, which I have no practical experience with. With this you will not
be able to measure tritium, so any measurement done with this instrument
will not suffer from any interference from tritium. C-14 is a pure
beta-emitter, but you will most probably not be able to measure a
radionuclide with this low energy with the instrument you mentioned.
Further pure beta emitters are of course Sr-90 and Y-90, but their
measurement will hardly be possible in any matrix without chemical
separation and special measurement equipment. As has been pointed out in
one answer, Cs-137 is a beta emitter, but in practice Cs-137  is nowadays
measured via the gamma-rays of the very shortlived daughter Ba-137m. Y-91
it to my knowledge a pure beta-emitter, but it is shortlived and only
present in fresh fallout from a nuclear accident. Other pure beta-emitters
from the natural decay chains are associated with gamma-emitting daughters,
so their concentration can be measured by gamma-spectrometry.

In principle I have always had and still have the opinion that activity
concentration measurements with GM-detectors in contamination monitors are
not possible, unless only one radionuclide is present and it has been
carefully calibrated with the same radionuclide in question and the same
geometry. We have successfully used liquid scintillation spectrometry for
measurement of beta-emitters and developed simple methods for various
radionuclides.

Any specific questions are welcome and I will try to delete in the future
all basic ones.

With my best 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

Office:
Federal Institute for Food Control and Research
Department of Radiochemistry
Kinderspitalg. 15
A-1095 Vienna
Austria
Tel.: +43-1-40 491 520
Fax.: +43-1-40 491 540
e-mail: schoenhofer@baluf.via.at
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