The experience of exploitation of a a§b-radiometer UMF-2000 with «SpDec» software in spectrometric mode was described. Good linear approximation was shown for energ calibration curve for a-emitters (18 isotopes), whereas the similar energy calibration curve for bemitters (8 isotopes) showed bad linear approximation. Some limitations in identification of a-emitters due to low energy resolution of spectra, emanation of radon isotopes from sources and difference in source thickness were described. The device was tested using two samples of natural water with a high uranium content.