A Gas-Phase UF₆ Enrichment Monitor

A NaI(Tl)-based in-line enrichment monitor has been developed for the gas-phase UF₆ feed stream of an enrichment plant to provide real-time material-accountancy and/or containment-surveillance data. The method has produced assay results that are independent of operating UF₆ pressure, with an assay accuracy of better than 1% (1σ) relative over the range of UF₆ enrichments of 0.72 to 5.4 at.%. For 1.0%-enriched UF₆ at 700 Torr, a 0.74% relative precision was obtained for a 1000-s counting time. As a result of these measurements, an in-line gas-phase enrichment monitor has been installed in the Paducah-product feed line of the Oak Ridge Gaseous Diffusion Plant for field test and evaluation.