The stability under irradiation of hollandite ceramics, specific radioactive cesium-host wasteforms
Résumé
Investigations are currently performed on matrices for the specific immobilization of long-lived radionuclides such as fission products resulting from an enhanced reprocessing of spent fuel. Hollandite (nominally BaAl2Ti6O16), one of the phases constituting Synroc, receives renewed interest as specific Cs-host wasteform. The radioactive cesium isotopes decay involves the emission of $\beta$ particles, $\gama$ rays and the transmutation of Cs to stable Ba ions. This study deals with the synthesis of hollandite ceramics by oxide route and single crystals by a flux method having the BaxCsy(Al,Fe)2x+yTi8-2x-yO16 composition type (1 <= x <= 1.28; 0 <= y <= 0.28). The influence of the hollandite chemical composition on the hollandite structure and microstructure is studied. To estimate the hollandite radiation resistance, external electron irradiation experiments, simulating the $\beta$ particles emitted by radioactive cesium, were carried on single phase materials. The radiation effects were characterized by electron paramagnetic resonance (EPR) and Mössbauer spectroscopy.
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