Year
2022
Abstract
One of the International Atomic Energy Agency’s (IAEA) main tasks is to verify the peaceful use of nuclear material and technologies concerning the Treaty on Non-Proliferation. Hence, technical measures – the IAEA Safeguards - were introduced to assure the compliance with the treaty by its member states. Among other safeguard measures, the IAEA conducts inspections of nuclear facilities, during which swipe samples are taken by the delegates. These environmental samples are sent to the IAEA and its dedicated Network of Analytical Laboratories (NWAL) for elemental and isotopic analysis of the microparticles attached to these swipe samples. To ensure the quality of these measurements, microparticle reference materials that are similar to the environmental samples in size and shape as well as isotopic and elemental composition are needed. The first certified microparticle reference materials were produced in the laboratories of the Forschungszentrum Jülich (FZJ) using a Vibrating Orifice Aerosol Generator (VOAG).
For a sustainable application of a potential reference material, a certain shelf-life must be guaranteed. However, previous studies have demonstrated that uranium oxide microparticles undergo alteration leading to formation of uranium hydroxides. To investigate the alteration of uranium microparticles, a systematic shelf-life study has been launched. Uranium microparticles deposited on graphite planchets are stored under different atmospheric conditions as well as in different solvent media, and regularly measured using Scanning Electron Microscopy (SEM), µ-Raman Spectroscopy and Secondary Ion Mass Spectrometry (SIMS). These methods are used to check the stability of the particles in suspension and under atmospheric conditions to identify the optimal storage conditions for potential uranium microparticle reference materials. In this presentation first results of both, atmospheric and suspension shelf-life studies will be discussed.