<> "The repository administrator has not yet configured an RDF license."^^ . <> . . "Characterization of Uranium Oxide Microparticles for Quality Control in Nuclear Safeguards Applications"^^ . "The International Atomic Energy Agency’s (IAEA) main goal is the support and development of nuclear technology for non-military purposes. This includes the verification of peaceful use of nuclear material and technologies within the Treaty on the Non-Proliferation of Nuclear Weapons (NPT). Therefore, technical measures – the IAEA Safeguards – were introduced to assure the compliance with the treaty by its member states. Among other safeguards measures, the IAEA conducts inspections of nuclear facilities during which environmental swipe samples are taken by the delegates. The dust grains in these environmental samples are shipped to the IAEA Safeguards Analytical Services’ Environmental Sampling Laboratory (SGAS-ESL) and IAEA’s worldwide partners in the Network of Analytical Laboratories (NWAL) for isotopic abundance analysis using mass-spectrometric techniques such as Large Geometry-Secondary Ion Mass Spectrometry (LG-SIMS). The goal of these analyses is either to confirm the handling of nuclear material according to the member state’s declarations to the IAEA or to reveal undeclared activities.\r\nTo ensure the quality of these measurements, microparticle reference materials that are similar to the environmental samples in shape and size as well as elemental and isotopic composition are of dire need. In the safeguards laboratories of Forschungszentrum Jülich (FZJ), an aerosol-based process is used for the production of potential uranium oxide microparticle reference materials. However, capacities for characterization measurements of potential reference materials are limited. Thus, the microparticles produced in FZJ are analyzed in the Heidelberg Ion Probe (HIP) laboratories at the Institute of Earth Sciences, Heidelberg University as part of a cooperation program.\r\nIn this thesis, the implementation of a transparent and effective measurement setup at the HIP lab is described. First approaches built up on an already prevalent configuration yielded promising results for the isotopic abundance measurements of single particles, but were not suitable for the characterization of an entire particle population with the CAMECA-developed Automated Particle Measurement (APM) software. A second approach based on the IAEA SGAS-ESL measurement protocol resulted in satisfying results for both single particle analyses and measurements of entire particle planchets with the APM software. The functionality of this setup was confirmed by the measurement of FZJ-produced aerosol-generated uranium oxide microparticles and certified reference materials from New Brunswick Laboratory’s (NBL) “CRM U” series.\r\nWithin the work of this thesis, three IAEA-requested batches of microparticulate reference materials were characterized using LG-SIMS. The characterization process of two batches, FZJ-3050P and FZJ-3090P is described here. The measurements confirmed the compliance with the IAEA requirements for potential reference materials. The isotopic composition of a pre-defined number of random single particles measurements was in good agreement with the certificate values of the source material. APM measurements excluded the possibility of contamination with material of different uranium isotopic composition and confirmed the requested number of particles on a sample planchet as well as their homogeneous distributionThe results for both particle batches together with quality control measurements for the cleaning step used in the FZJ safeguards laboratories verified the suitability and high-quality standards of the aerosol-based microparticle production process used by the particle producers of FZJ.\r\nA core requirement for a potential microparticulate reference material is the assurance of a practical shelf-life. Previous studies of uranium oxide microparticles produced with an aerosol-based process demonstrated possible alteration leading to the formation of uranium hydroxides like schoepite. To address these issues, a comprehensive shelf-life investigation of uranium oxide microparticles was conducted. Particle stability in three different potentially suitable atmospheric storage conditions with an additional sample in an unrealistically harsh fourth environment to accelerate possible alteration was investigated. Accordingly, particle shelf-life in dispersions with four alcoholic potential long-term storage media was examined. After more than one year, the investigations confirmed the hypothesis that the microparticle shelf-life heavily depends on the amount of water in the respective storage conditions. Continuous storage in a water-saturated atmosphere lead to alteration, formation of uranyl hydroperoxides, uranium mobilization and fractionation and therefore rendered the particles useless for the purpose as reference material. The other three conditions kept the particles stable over the course of the investigation with an inert argon atmosphere showing the most promising results. Accordingly, the isotopic abundance in all four alcoholic storage media remained unchanged over the course of nearly two years. Particles stored in tert-butanol showed the highest stability.\r\nSome additional insights for the measurement of uranium oxide microparticles could be obtained in measurement sessions over the course of three years. Examples are the possible influence of secondary ion beam aberrations, measurement dependency on sample stage focus and sample area signal. This leads to the conclusion, that a reliable measurement setup for uranium microparticles needs continuous review and development."^^ . "2025" . . . . . . . "Simon"^^ . "Hammerich"^^ . "Simon Hammerich"^^ . . . . . . "Characterization of Uranium Oxide Microparticles for Quality Control in Nuclear Safeguards Applications (PDF)"^^ . . . "DissertationSimonHammerich.pdf"^^ . . . "Characterization of Uranium Oxide Microparticles for Quality Control in Nuclear Safeguards Applications (Other)"^^ . . . . . . "indexcodes.txt"^^ . . . "Characterization of Uranium Oxide Microparticles for Quality Control in Nuclear Safeguards Applications (Other)"^^ . . . . . . "lightbox.jpg"^^ . . . "Characterization of Uranium Oxide Microparticles for Quality Control in Nuclear Safeguards Applications (Other)"^^ . . . . . . "preview.jpg"^^ . . . "Characterization of Uranium Oxide Microparticles for Quality Control in Nuclear Safeguards Applications (Other)"^^ . . . . . . "medium.jpg"^^ . . . "Characterization of Uranium Oxide Microparticles for Quality Control in Nuclear Safeguards Applications (Other)"^^ . . . . . . "small.jpg"^^ . . "HTML Summary of #35847 \n\nCharacterization of Uranium Oxide Microparticles for Quality Control in Nuclear Safeguards Applications\n\n" . "text/html" . . . "550 Geowissenschaften"@de . "550 Earth sciences"@en . .