Characterization of high thermal conductivity fuel surrogates before and after ion irradiation

•Thermal conductivity of UO2 surrogates was enhanced during sintering using aluminum oxide and silicon carbide additives.•Compositions were stable up to 5 dpa and 700 °C while a decrease in their mechanical properties was observed at 15 dpa.•Microcrack formation due to anisotropic swelling of the additives was not observed.