Neutron irradiation effects on the low cycle thermal fatigue performance of first wall mock-ups

•Comparative high heat flux experiments on Be-armored first wall test components.•Five mock-ups neutron irradiated up to 1 dpa and five non-irradiated references.•Heat loads from 1 MW/m2 to 3.75 MW/m2 with a maximum of 2300 cycles.•All irradiated components could sustain at least 500 cycles at 2.4 MW/m2 without deterioration.•A spontaneous, brittle detachment was the failure mode for the highly (1 dpa) damaged tiles.