Fundamental study of electron irradiation effects on nuclear materials

The objective of this study is to clarify the fundamental process of the evolution of the damage structure by the electron irradiation in the nuclear materials, such as Fe-Cu alloy and others by means of the experimental methods and computer simulation technique. Furthermore, basic properties of defect clusters which are very responsible for the establishment of damage structure has been widely investigated. In the low temperature electron irradiated Fe-Cu alloys it was made clear that radiation induced defects strongly interact with Cu atoms, and radiation enhanced precipitation of Cu atoms occurs by means of the positron annihilation lifetime measurement and the electrical resistivity measurement. In the computer simulation of small interstitial clusters in Fe and Ni the very high mobility of clusters was found and this result supported the production bias concept developed in the recent cascade damage simulation. The interaction between a dislocation and defects, defect clusters was also made clear in atomic level, which contributes to the understanding of the mechanism of radiation hardening. (J.P.N.)