Title: Uranium Microparticle Production - Support of IAEA's Analytical Capabilities
Publisher: ESARDA
Publication Year: 2017
JRC N°: JRC105413
URI: https://esarda.jrc.ec.europa.eu/index.php?option=com_content&view=article&id=303&Itemid=350
Type: Articles in periodicals and books
Abstract: The goal of a collaborative effort between the International Atomic Energy Agency (IAEA) and the Forschungszentrum Jülich GmbH (FZJ) is to produce monodisperse microparticles for nuclear safeguards applications in order to strengthen the IAEA's analytical capabilities to detect illicit nuclear activities. These particles are intended to serve for quality control purposes and eventually as certified reference materials for mass spectrometry. Therefore, the principal requirement is the consistency concerning the number of uranium atoms per particle, but also a homogenous size distribution, a consistent isotopic composition and uniform particle morphology. This work focuses on different aspects of the particle production process, including (1) development and implementation of the particle generation process and (2) particle collection techniques as well as (3) substrate and sample preparation techniques for further analysis and (4) particle size distribution using scanning electron microscopy (SEM) and large geometry secondary ionization mass spectrometry (LG-SIMS) for determination of the isotopic ratios. A working microparticle setup was developed and implemented at FZJ. The entire setup is designed as a closed system to mitigate the risk of contaminations. Monodisperse uranium oxide particles are generated by spray pyrolysis and particles are collected by inertial impaction on vitreous carbon substrates. Furthermore, substrates can be prepared in advance with reference marks to facilitate particle identification and relocation of single particles with high precision in different analytical instruments. Customizable reference marks were engraved using a laser micro dissection instrument (LMD). Collection efficiency assessment of two different inertial impactor designs, a one-stage inertial impactor and a modified cyclone impactor, are in agreement with the theoretical predictions. A consistent particle size distribution, a homogeneous morphology and the presence of uranium was confirmed using SEM-EDX. LG-SIMS analysis performed on single uranium microparticles confirmed consistency of the uranium isotopic ratios in comparison to the initial precursor solutions.
JRC Directorate:Nuclear Safety and Security

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