AbstractIn laser IFE reactors the reflectivity and absorptivity of the grazing incidence metal mirror (GIMM) depend on the neutron dose received by the mirror surface. In addition to this effect, surface deformation caused by neutron-irradiation-induced swelling and due to thermal load changes the focusing quality of the mirror. In the present work, we present the database for material selection of the final GIMM of the Prometheus-L IFE reactor. A unique design for the GIMM, which accounts for mirror surface deformation by thermal and swelling effects is then presented.