Precipitate stability and swelling resistance of high-nickel alloy during irradiation

Inoue, Toshihiko ; Yamashita, Shinichiro   ; Yamagata, Ichiro ; Yoshitake, Tsunemitsu ; Kaito, Takeji ; Sekio, Yoshihiro  ; Hayashi, Takehiro

Precipitation-strengthened high-nickel alloys have been developed for fuel cladding material in advanced reactor because of their intrinsic superior swelling property. In most case, Nimonic PE16 and these high-nickel alloys are strengthened by an intermetalic compound such as ordered phase gannma- formed in the matrix. The most important issue in development of high-nickel alloy is considered to be the improvement of mechanical properties at elevated temperature; the significant ductility loss due to irradiation at high temperature. The cause of this problem was believed to be the re-distribution of ordered phase gannma- and solute segregation to defect sink sites, such as grain boundary, dislocation and void surface, during irradiation. In this study, several types of precipitation-strengthened high-nickel alloys, which were stabilized by were carbide/nitride and gannma double prime phase, were developed and then the phase stability (precipitate stability and swelling resistance) in these alloys during irradiation was evaluated by utilizing TIARA facility. In the results, high nickel steel were confirmed more higher resistance of swelling than PNC316 steels.