U1-xAmxO2±δ solid solution study


U1-xAmxO2±δ solid solution study

Lebreton, F.; Martin, P. M.; Belin, R. C.; Horlait, D.; Dardenne, K.; Rothe, J.; Rossberg, A.; Scheinost, A. C.; Delahaye, T.; Blanchart, P.

Americium isotopes are produced in nuclear fuels in low amounts (< 0.1 wt.%) by successive neutron captures during irradiation in power reactors. Due to its high activity and long half-life, this element is responsible for the second highest contribution (after plutonium isotopes) to the radiotoxicity and heat load of spent fuels after a hundred years. In order to lower this radiotoxicity and decrease the ecological footprint of ultimate nuclear wastes, transmutation of americium in fast neutron reactors appears to be a possible solution, notably in heterogeneous mode, i.e., through the use of (U,Am)O2 MABB (Minor Actinide Bearing Blanket) fuels destined for the periphery of the core.
In this context, research is being conducted at the Atalante facility not only on the development of fabrication processes for such fuels, but also on the acquisition of data on their fundamental properties. In this work, we report recent experiments performed notably by HT-XRD (high-temperature X-ray diffraction) and XAS (X-ray absorption spectroscopy) which seek a better understanding of the U1-xAmxO2 solid solution over a wide range of compositions (up to x = 0.5). The discussion is mainly focused on: (1) the specific cationic charge distribution in these materials, (2) its influence on the solid solution formation via solid state reaction and (3) on their oxidation behaviour when in contact with different atmospheres (reducing, neutral).

Keywords: Fourth generation nuclear fuel; Americium; oxidation state; ROBL; XANES

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Publ.-Id: 18820