Book/Dissertation / PhD Thesis

FZJ-2017-07401

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Monazite-type ceramics for conditioning of minor actinides: structural characterization and properties

Babelot, C. (Corresponding author)FZJ*

2013
Forschungszentrum Jülich GmbH Zentralbibliothek,Verlag Jülich
ISBN: 978-3-89336-889-1

Please use a persistent id in citations: http://hdl.handle.net/2128/15815

Abstract: The minor actinides (MA) neptunium, americium, and curium are mainly responsible for the long-term radiotoxicity of the High Active Waste (HAW) generated during thenuclear power operation. If these long-lived radionuclides are removed from the HAW by partitioning and converted by neutron fission (transmutation) into shorter-lived or stable elements, the remaining waste loses most of its long-term radiotoxicity. Thus, partitioning and transmutation (P&T) are considered as attractive options for reducing the burden on geological disposals. As an alternative, these separated MA can also be conditioned (P&C strategy) in specifically adapted ceramics to ensure their safe finaldisposal over long periods. At the moment, spent fuel elements are foreseen either for direct disposal in deep geological repositories or for reprocessing. The highly activeliquid waste that is produced during reprocessing is conditioned industrially using a vitrification process before final disposal. Although the widely used borosilicate glassesmeet most of the specifications needed, ceramic host matrices appear to be even more suitable in terms of resistance to corrosion. The development of new materials based on tailor-made highly specific ceramics with extremely stable behavior would make it possible to improve the final storage of long-lived high-level radiotoxic waste.In the framework of this PhD research project, monazite-type ceramics were chosen as promising host matrices for the conditioning of trivalent actinides. The focus on themonazite-type ceramics is justified by their properties such as high chemical durability. REPO$_{4}$ ceramics are named monazite for RE = La - Gd (monoclinic symmetry) and xenotime for RE = Tb - Lu and Y (tetragonal symmetry). The objective of this study is to contribute to the understanding of the alteration behavior of such ceramics under the repository conditions. REPO$_{4}$ (with RE = La, Eu) is prepared by hydrothermal synthesis at 200°C. Structural and morphological characteristics (using X-ray diffraction (XRD) and scanning electron microscope (SEM)) combined with physical and thermal properties of samples (using thermogravimetry, differential scanning calorimetry (TG-DSC) and dilatometry) are realized in order to study the behavior of monazite-type powder and pellets. The access to short-range-order spectroscopy (time resolved laser fluorescence spectroscopy (TRLFS) and extended X-ray absorption fine structure (EXAFS)) permits to [...]

Keyword(s): Monazit

Note: Dissertation, RWTH Aachen, 2012

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Contributing Institute(s):

1. Nukleare Entsorgung und Reaktorsicherheit (IEK-6)

Research Program(s):

1. 899 - ohne Topic (POF3-899) (POF3-899)

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Database coverage:

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