[en] In order to study the elementary damaging processes of neutron-irradiated metals, damage parameters such as the PKA energy spectrum, the integrated damage energy due to PKAs below an energy E_PKA and the gas atom production were calculated for various neutron energy spectra. The present status of computer simulations of the formation of displacement damage cascades is summarized. We carried out the cryotransfer electron microscope observation of neutron-irradiated specimens to examine the structure of displacement damage cascades after the cooling phase of their formation. It is clarified that damage formation processes in neutron-irradiated metals are dynamical and indispensable to understand fully the damage structure evolution on high temperature irradiation. (author)