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 as sembly with 9 Faraday cups has been reported earlier, Subsequently inv estigations have been carried out (1) to understand the applicability of correction methodologies available to account for the contribution of Pu-238 at U-238 and (2) to evaluate the effectiveness of these meth odologies on the accuracy of U-235/U-238 atom ratio being determined, particularly when samples containing different U/Pu atom ratios. Isoto pic fractionation for both U and Pu in the simultaneous isotopic analy sis has been compared with the results of the individual analysis of t hese elements. The different isotopic fractionation factors observed f or 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 ob servations on synthetic samples with diferent U/Pu atom ratios contain ing U and Pu isotopic reference standards is described.