Synthesis and characterization of homogeneous (U,Am)O2 and (U,Pu,Am)O2 nanopowders

This paper details on the first dedicated production of homogeneous nanocrystalline particles of mixed actinide oxide solid solutions with americium content. The target compositions were U0.75Pu0.20Am0.05O2, U0.90Am0.10O2 and U0.80Am0.20O2. After successful synthesis and chemical characterisation, the nanocrystals were sintered and their structure and behaviour under self-irradiation were studied by powder XRD. Cationic charge distribution was investigated for as pre-prepared nanocrystalline and for sintered U0.80Am0.20O2 applying U M4 and Am M5 edge high energy resolution XANES (HR-XANES). Typical oxidation states detected for the cations are U(IV)/U(V) and Am(III)/Am(IV). The measured crystallographic swelling was systematically smaller for the as-synthesised nanoparticles than compared to the sintered products. For sintered pellets, the maximal volumetric swelling was about 0.8 % at saturation, in line with PuO2, AmO2, (U,Pu)O2 or (U,Am)O2.

VIGIER Jean-Francois;  FREIS Daniel;  WALTER Olaf;  DIESTE BLANCO Oliver;  BOUEXIERE Daniel;  ZULEGER Evelyn;  PALINA Natalie;  VITOVA Tonya;  KONINGS Rudy;  POPA Karin; 

2022-09-26

ROYAL SOC CHEMISTRY

JRC129071

1466-8033 (online),   

https://pubs.rsc.org/en/content/articlelanding/2022/ce/d2ce00527a,    https://publications.jrc.ec.europa.eu/repository/handle/JRC129071,   

10.1039/d2ce00527a (online),