Microstructural analysis on ion- and neutron-irradiated reactor pressure vessel steel using XAFS methods

Iwata, Keiko ; Ha, Yoosung  ; Takamizawa, Hisashi ; Shimodaira, Masaki ; Katsuyama, Jinya  ; Okamoto, Yoshihiro  ; Honda, Mitsunori   ; Toyama, Takeshi*; Nishiyama, Yutaka 

In this study, we performed that extended X-ray absorption fine structure (EXAFS) analysis for ion- and neutron-irradiated reactor pressure vessel (RPV) steel to investigate microstructural changes of solute atom clusters induced by irradiation. To verify changes of EXAFS spectra recognized in ion-irradiated samples, we constructed lattice structure models with defects induced by irradiation and calculated theoretical EXAFS spectra for these models. Comparison between measured spectra and EXAFS simulations suggests that tensile-type interstitials or vacancy defects could be located around Cu and Ni atoms. Although the improvement for decreasing of noise in measured spectra at Cu K-edge, we will indicate that microstructure around Cu atoms may change from bcc structure due to irradiation.