Multi-scale structural investigation of uranium-plutonium mixed oxides (U1-yPuy)O2-x with high plutonium content

• Published in: Journal of nuclear materials 2023-11, Vol.585, p.154645, Article 154645
• Main Authors: Desagulier, M-M., Martinez, J., Martin, P.M., Lebreton, F., Guéneau, C., Clavier, N.
• Format: Article
• Language: English
• Subjects: Chemical Sciences; Chracterizations; Co-milling; Manufacturing; Material chemistry; Mixed-oxides
• ISSN: 0022-3115; 1873-4820
• DOI: 10.1016/j.jnucmat.2023.154645

Uranium-Plutonium mixed oxides U1-yPuyO2-x are considered as the reference fuels for Sodium-cooled Fast neutron Reactors (SFRs). Nevertheless, there is a lack of experimental data on their thermal properties for a Pu content above 0.45. The first step to fill this gap is to manufacture samples with high plutonium contents, which is the purpose of this work. Here, the manufacturing of U1-yPuyO2 samples with y = 0.60, 0.65 and 0.70 by a co-milling powder metallurgy process is detailed. Relying on an optimization of each manufacturing step (blending, co-milling, sieving, pelletizing and sintering), in order to obtain dense, monophasic, stoichiometric and homogenous materials. A multi-scale characterization strategy was used to determine sample microstructural properties including density measurements, Thermal-Ionization Mass Spectrometer (TIMS), ceramography, Electron Probe Micro Analyses, µ-Raman Spectroscopy and X-Ray Diffraction. The results obtained show that dense (> 95% TD), homogenous (chemical distribution of cations and oxygen), monophasic and stoichiometric (O/M = 2.00) samples have been achieved. These properties correspond to those needed to optimize the thermo-physical properties measurements. This also shows that the coupling of multi-scale characterizations is mandatory to evaluate the structural and microstructural properties of this kind of material.