Isotopic Analysis of Uranium Hexafluoride

Once a sample is collected, the isotopic composition of uranium must be determined as the content is one of the main factors that determine the price of the product. Several mass spectrometric techniques have been developed for direct isotope analysis of gaseous UFg and for indirect analysis (usually after hydrolysis) of liquid and gaseous UFg samples. The use of a thermal ionization mass spectrometer (TIMS), nowadays equipped with several detectors (i.e., multicollector TIMS), has been the method of choice for many years, but the sample must be hydrolyzed to liquid form (uranyl fluoride or uranyl nitrate solutions) and the uranium must be purified (usually not a problem for UFg samples), as mentioned, for example, by ASTM (C1413 2011). The method is used for hydrolyzed samples of UFg (UOjFj (uranyl fluoride)) or for [Pg.83]

Direct determination of the isotopic composition of uranium in gaseous UFg requires no sample preparation and purification, but the accuracy of the method was limited. However, a dedicated UFg gas source mass spectrometer (GSMS) was used and a procedure for accurate measurement of the isotopic composition of uranium was developed (Richter et al. 2013). A memory corrected double standard (MCDS) procedure was implemented and the results were favorably compared with those obtained with a TIMS device employing modified total evaporation. [Pg.85]

The potential of an online uranium enrichment monitor for assaying the isotopic ratio in UFg gas at a centrifuge enrichment plant, based on calculations and Monte Carlo modeling, was presented (Smith and Lebrun 2011). The unattended monitor would be located on the high-pressure header pipes that receive the gas flow from multiple cascades. The online monitor is to be equipped with a Nal gamma detector for measurement of the 186 keV line from U. The major uncertainties are due to [Pg.85]

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