Re: Respect

[Franz Schoenhofer <schoenho@via.at>]

At 18:43 04.09.1998 -0500, you wrote:
>I can't give a very good LLD for H3 with a pancake but it would probably be
>in the curie range and would vary with the matrix that the tritium is in.
>
I work in a low-level measurements laboratory and in this case I would try
to remove the source so quick, that at the Olympics I would win the 100 m
race...... Tritium is a very nasty thing. 



>As for the Ni-63, we were dealing with ionization sources from Ion Mobility
>Spectrometers.  They were essentialy screens that had been electroplated.
>The researcher had cut a screen with tin snips so it would fit into his
>device.  In order to prove that the contamination was from him and not
>legacy (which was not too improbable for this lab) we took swipes of known
>Ni-63 and tritium contamination.  We then printed out the energy spectrums,
>turned them into transparencies and overlayed them on the spectrums from
>his lab.  And imagine our suprise when the Ni-63 spectrum matched his to a
>tee.  It also helped that the spectrum tailed off around the 30 keV area
>which obviously discounts tritium.   Not a very scientific approach but it
>was good enough.

I think it is a very scientific approach, because it resembles very much
the "internal standard method". We have used this method successfully for
instance to prove that a contamination in the waste water of a nuclear
research institute was not caused by plutonium, by simply comparing the
spectra. (We have published a paper, if you or other radsafers are
interested in it, I can fax it.)

Did you experience any interference by chemiluminescene? The interference
of chemiluminescence with low energy beta-emitters was a thread on RADSAFE
not so long ago.

 His sources, which were about 10 mCi were easily detected
>with a PGM.

Could you also give a LLD for that? For smear samples (like for electron
captur detectors) this method might probably not be easily applicable.


Anybody on radsafe who has experience with Ni-63 smearsamples from EC
detectors and LSC measurement? 

Thanks for your information.

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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