RADIOACTIVE METHOD FOR THE DETERMINATION OF TRACE TECHNETIUM-99 IN URANIUM HEXAFLUORIDE

An analytical method was recommended in this paper. The ~(99)Tc was extrac-ted from the Na_2CO_3 solution containing large quantities of uranium and fluorineusing methyl ethyl ketone as an extractant and was determined by counting its β-particules. The extractive characteristics of methyl ethyl ketone, 2,6--dimethylpyridine,tetraamine--7402 and methyl isobutyl ketone and the effect of the time of equili-brium and of the concentrations of carbonate, uranium and fluorine in the aqueoussolution on the extraction and the removal of radioactive impurities werestudies. Samples of UF_6 were analysed and the results were compared using threecounting devices (liquid scintillation counter, low background counter, with abackground of only 1.5--2 cpm and ordinary GM counter, with a background ofabout 30 cpm). The results indicated that the three devides was satisfactory for the countingwhen the quantities of ~(99)Tc was more than 0.25μg in 100 mg U samples. The method is simple, ripid and sensitive. The relative standard deviation for10 parallel samples is 2.5%. The percentage recovery is 98--101%. The decon--tamination factor for the removal of the radioactive impurities is more than 1×10~3.