This work shows an ongoing study of the influence of neutron irradiation on the hardness of first wall structure materials. EUROFER97 and boron-doped steels have been neutron-irradiated in the European High Flux Reactor (HFR) with an average dose of up to 16 dpa at temperatures between 250 and 450 °C. The irradiated samples are investigated by the advanced method of a registering hardness measurement that is used to perform experiments at temperatures of up to 450 °C. The first part of this work examines the hardening of EUROFER97 depending on the irradiation temperature at different test temperatures.
In addition, post-irradiation annealing is applied to EUROFER97 and to the boron-doped steels. The different contents of boron lead to different amounts of helium generated by neutron-irradiation. Since post-irradiation annealing is known to enable the neutron-induced Frenkel pairs and nanoscale defects to recombine, the remaining hardening after the annealing process can be attributed mostly to products of transmutation reactions. Thus, the potential as well as the limits of this promising treatment are explored.