Year
2007
Abstract
In the oversight of the nuclear non-proliferation treaty and as part of the Additional Protocol of the International Atomic Energy Agency, environmental sampling has become an important tool for the detection of non-declared nuclear activities. Micrometer-sized uranium particles are collected from nuclear installations using swipes and are subsequently analyzed by highly sensitive and selective methods. In order to improve the accuracy and detection efficiency of the different measurements techniques, reference uranium particles are needed that are similar in physical and chemical characteristics to the particles found in swipes. The method that is currently under development at the Institute for Reference Materials and Measurements focuses on enrichment facilities and is based on the controlled hydrolysis of uranium hexafluoride with a certified isotopic composition. The morphology and composition of the particles produced was found to be dependent on the relative humidity of the air, the exposure to ultraviolet light and the time elapsed after formation. The particles were characterized using scanning electron microscopy combined with energy dispersive-X-ray analysis, micro-Raman and secondary ion mass spectrometry. The particles will be used for nuclear signatures inter-laboratory measurement evaluation programs (NUSIMEP).