Study on Radiation Effects in Austenitic Stainless Steels Used in Light Water Reactors

摘要

Irradiation-assisted stress-corrosion cracking (LASCC) in core internals made of austenitic stainless steels has become one of the most pressing problems in both pressurized water reactors (PWRs) and boiling water reactors (BWRs). Besides, more attention has been paid these days for void swelling problem of long-term used core internals. In this study, existing and alternative alloys for core internals were irradiated with light ion beams using Dynamitron accelerator in Tohoku University. The test alloy consisted of SUS304 SUS347, SUS310+Nb and XM-19. The light ion irradiation was carried out through two steps using two ion particles: 3 MeV helium ion was implanted at room temperature up to 15 appm to simulate Ni(n,α) reaction in austenitic stainless steel followed by 2 MeV H2~+ ion irradiation at 300 ℃ up to a dose of ldpa. The dose rate of the H2~+ ion irradiation was approximately 4 X10~(-5) dpa/sec. Following the irradiation, small cavities and an increase in dislocation density were observed for all the test alloys irradiated in this study. The size and density of the cavities significantly depended on He pre-injection and dose of irradiated H2~+ ion of the test alloys. Based on the TEM observation, the results were discussed focusing on a relationship between dose of irradiated H2~+ ion and radiation effects on microstructure. This report shows the part of the result of joint R&D program which was carried out by, The Kansai Electric Power Co.,INC, Tohoku university and Nuclear Fuel Industries Ltd.