Ultra Low-Level Liquid
Scintillation Spectrometry, Application to Rapid Measurement and Decision
Making
Franz
Schönhofer
Federal
Ministry for Agriculture, Forestry, Environment and Water Management,
Department of Radiation Protection
Liquid scintillation spectrometry (LSC) is an excellent
tool for counting of beta- and alpha-emitters. Development of new counters
since 1983, which among other new features are equipped with active shield, MCA
technique and alpha-beta separation, has led to very interesting applications
not only in ultra low-level counting, but also to the use in other applications
which were not possible before. This
paper describes the use of ultra-low-level liquid scintillation counters for
applications like fast survey measurements, using the advantages of these new
instrumentation. Time, manpower, costs for chemicals etc. can be saved and in
cases, when very quick decisions have to be made, for instance after accidents,
the saying “Time is money” becomes an essential feature. The four instruments
“Quantulus“, (Wallac Oy), which we have used both for routine purposes and to
answer urgent, rather unconventional questions, have not only very low
background, which cuts measurement time considerably, but from the pulse height
spectra much information about the nature of the radionuclides present - and
often about the absence of specific radionuclides - can be extracted.
Several examples will be given for the application of ultra
low-level liquid scintillation spectrometers for instance concerning the
Chernobyl accident, detection and identification of contamination, fast
decision
of compliance of waste water from nuclear installations including a
semi-quantitative determination and nuclide specific identification of
contaminants, ground water contamination with artificial and natural
radionuclides, incorporation of radionuclides, as well as fast drinking water
surveillance and rapid determination of radon-222 in hundreds of samples within
short time.