Fission-product behaviour in irradiated TRISO-coated particles: Results of the HFR-EU1bis experiment and their interpretation

► The microstructure and FPs in UO2 TRISO particles (10% FIMA, 1573 K) were studied. ► Very large porosities (>10 μm) were observed in the high temperature particles. ► Significant Xe and Cs releases from the kernel were observed. ► Mo and Ru are mainly present in the metallic precipitates in the kernel.