Abstract

The uranium enrichment enterprise in the United States uses the gaseous diffusion method to achieve the desired level of enrichment of the ²³⁵U isotope. The feedstock for this process is gaseous uranium hexafluoride (UF₆). In addition to the current production facilities there are also facilities which have been idled due to programmatic reasons, but may still contain residual, low levels of (UF₆). For the case of certain of these industrial processes or laboratory scale applications, the need to observe low levels of uranium hexafluoride (UF₆), often in the presence of other gases, is an important, but difficult, problem. UF₆ is a highly reactive gas particularly when acting as a fluorinating agent, and is very reactive with even trace levels of moisture. For these reasons, meticulous chemical drying techniques and containment vessels of suitable materials must be used. An accepted manner of analysis for the detection of UF₆ is to use a Fourier-transform infrared (FTIR) spectrometer. These units work reasonably well for observing UF₆ levels on the order of a few dozen ppm, but the reactive nature of the gas greatly limits the choice of infrared windows. The fundamental vibration of interest in UF₆ is the v₃ band at ~ 625 wavenumbers, but spectral interferences can occur from other gaseous species which may be mixed with the UF₆ thereby complicating the analysis. We describe a laser technique which can provide sub-ppm levels of detection for UF₆ in the presence of other gases using commonly available laser hardware.

© 1996 Optical Society of America