Modeling Vapor-Liquid Equilibrium of UF6 (uranium hexaflouride) and Common Impurities.

摘要

In the safe handling and processing of uranium hexafluoride (UF sub 6 ), it is often desirable to calculate vapor composition and pressure from known liquid composition and temperature. Furthermore, it would be economically advantageous to the International Atomic Energy Agency (IAEA), in its international safeguards program, and to uranium enrichment operators to be able to use analyses of equilibrium vapor-phase samples to calculate liquid-phase compositions. Either type of calculation could be performed with a multicomponent vapor-liquid equilibrium (VLE) model if this model were shown to apply to UF sub 6 and its common impurities. In the present and earlier studies, the model and computer programs developed by J.M. Prausnitz and his coworkers has been adapted and tested for their ability to correlate experimental data on vapor-liquid equilibria between UF sub 6 and some of its many potential impurities. Because of its polymerization, hydrogen fluoride must be treated as a special component. However, VLE of the balance of components, including N sub 2 , O sub 2 , F sub 2 , SiF sub 4 , and ClF sub 3 , are accurately described by treating vapor-phase nonidealities by the Haydon-O'Connell equation and liquid-phase nonidealities by the UNIQUAC equation in the model of Prausnitz et al. This report describes the results of analyzing VLE involving UF sub 6 as a solute for some known impurities. It also describes the formation of F sub 2 and lower uranium fluorides from the self alpha -radiolytic decomposition of UF sub 6 . 68 refs., 7 figs., 7 tabs. (ERA citation 14:026314)