HIGH-PRECISION ISOTOPIC ANALYSES OF URANIUM AND PLUTONIUM BY TOTAL SAMPLE VOLATILIZATION AND SIGNAL INTEGRATION

Techniques have been developed that permit rapid, high-precision analyses of uranium and plutonium by multiple-filament thermal ionization mass spectrometry utilizing a commercial multicollector instrument. The salient feature of the method is volatilization of the entire sample while simultaneously integrating the signal from each isotope, thus virtually eliminating the effects of isotope fractionation in the evaporation process. The method permits the analysis of samples much smaller than required for conventional techniques using Faraday collectors and is expected to have application in the analysis of many elements in addition to uranium and plutonium. Run-to-run reproducibilities of < 0.02% RSD have been obtained for isotope ratios of uranium and plutonium.