Year
2011
Abstract
Nuclear safeguards at enrichment facilities largely relies on environmental sampling, where uranium particulate material is collected in swipe samples for mass spectrometric analysis. The fluorine-bearing uranium particles (UO2F2) found in these swipe samples are the reaction product of small releases of UF6 to the atmosphere. Even though mass spectrometric analysis remains the primary analytical method used in environmental sampling, additional morphological, elemental and spectral characterization of the collected particulate material would provide a more complete picture of the activities at the inspected facility. In this study, scanning electron microscopy combined with energy-dispersive X-ray analysis (SEM-EDX), nano-scale secondary ion mass spectrometry (NanoSIMS) and micro-Raman spectroscopy were applied in a multi-technique approach to the characterization of lab-synthesized UO2F2 particles. An important part of this work was devoted to the development of a relocation method that enabled the characterization of the same set of particles by SEM and NanoSIMS. Selected UO2F2 particles of specific morphology were identified and characterized by SEM before and after NanoSIMS analysis to determine whether a correlation exists between the particle morphology, the level of sputtering and the relative amount of fluorine.