Evaluation of neutron irradiation-induced displacement damage in heat pipe reactor

•Neutron irradiation-induced displacement damage in a 5 MW HPR is evaluated.•91 maximum DPA is obtained for the SS316 monolith after a reactivity-determined cycle length.•The more than 4% swelling of the monolith leads the refueling to be difficult.•The maximum neutron irradiation dose in the Al2O3 reflector is beyond available experimental data.•Two factors are proposed to convert the fast neutron fluences into DPA for Al2O3.