[en] Specimens of reactor pressure vessel steel 15Kh2MFA have been neutron irradiated in the Rossendorf research reactor up to neutron fluences of 1.4 x 10¹⁹ n/cm² (E > 1 MeV) at temperatures between 92 and 156 ⁰C. Strength and deformation parameters obtained from tensile test measurements clearly indicate the effect of neutron embrittlement and radiation hardening. Correlations could be found between the nondestructively measured properties hardness, coercive force and positron annihilation parameter S and yield strength as well as ultimate tensile strength. By thermal annealing of irradiated specimens it was impossible to reach the non-irradiated state of the steel, characterized by positron annihilation parameter S and hardness. (author)