A new approach to simultaneous activity measurements of the complex radionuclide mixtures using liquid scintillation counting, which is applicable to the analysis of the environmental and technological samples, is presented. The method is based on specially developed software 'SpectraDec', realized on a Windows 95/98/NT platform and a spectra library created for different kinds and levels of quenching. The method allows analysis of complex mixtures when the activity ratios of the individual components vary considerably, For example, the radionuclide concentrations were successfully determined in the following complex mixture: H-3, Ni-63, Sr-90 + Y-90, Cs-137, Am-241 (model mixture), where the Sr-90 + Y-90/H-3 activity ratio was 1/2500 (0.2 Bq/500 Bq) and Sr-90, Cs-137, Cs-134, Th-232, Ra-226 (IAEA-reference sample), where the Sr-90/Cs-137 activity ratio was 1/50 (92 Bq/4515 Bq) with an accuracy of about 20%, The limitations of the given approach to the LS analysis of the radionuclide mixtures are considered. (C) 2000 Published by Elsevier Science Ltd. All rights reserved.
