Non radiochemical technique for

Nondestructive methods of 90Sr determination were developed for small biological objects, such as small rodents, to keep biological object going for further research even in presence of essential contamination of the same object by 137Cs. To carry out 137Cs input registration in proper way, we used 2 different methods: a) The method of Cs and Sr electrons filtering using thin filters with subsequent measurement of residual Y-spectrum. Comparative results of measurements for calibrated and studied samples were found not hard to obtain the amount of 90Sr. Obtained result is close to the real one if the ratio between Cs and Sr is comparable. In opposite case the method requires several measurements depending on 137Cs/90Sr relation b) Method of beta-gamma spectrometry with specially elaborated beta-gamma spectrometer and corresponding software. General distinction of this spectrometer from the standard one is using the special procedure of experimental spectrum operation, and the use of thin (~1mm and 0,1mm) scintillator as a detector that allows to have the effectiveness of registration of gamma quanta of 661 keV in one-two orders less than for electrons with the same energy. The experimental spectrum operation was realised by the method of inserting into one of the calibrated spectrums, which had been measured on the same spectrometer from specially fabricated phantoms of mice with known contents of 137Cs and 90Sr+90Y. Method provides contemporary content of 90Sr and 137Cs. Procedure of standard radiochemical determination for 90Sr contents conducted in 13 mice on the final stage of studies has confirmed the method reliability