Simultaneous analysis of uranium and plutonium using thermal ionization mass spectrometry

Simultaneous isotopic analysis of uranium and plutonium using thermal ionization mass spectrometer coupled to a multi-collector detection assembly with 9 Faraday cups has been reported earlier. Subsequently investigations have been carried out to understand the applicability of correction methodologies available to account for the contribution of 238Pu at 238U and to evaluate the effectiveness of these methodologies on the accuracy of 235U/238U atom ratio being determined, particularly when samples containing different U/Pu atom ratios. Isotopic fractionation for both U and Pu in the simultaneous isotopic analysis has been compared with the results of the individual analysis of these elements. The different isotopic fractionation factors observed for U were attributed to different conditions of analysis. There was no significant difference in the isotopic fractionation patterns for Pu. The consideration to extend this method to actual samples from our observation on synthetic samples with different U/Pu atom ratios containing U and Pu isotopic reference standards is described. (author) 23 refs.; 9 tabs