Cracking behavior and microstructure of austenitic stainless steels and alloy 690 irradiated in BOR-60 reactor, phase I.

Chen, Y. ; Chopra, O. K. ; Soppet, W. K. ; Shack, W. J. ; Yang, Y. ; Allen, T. R. ; Univ. of Wisconsin at Madison

关键词: AIR;    ALLOYS;    BOR-60 REACTOR;    DEFECTS;    ELONGATION;    FRACTURES;    IRRADIATION;    MICROSTRUCTURE;    PWR TYPE REACTORS;    SCREW DISLOCATIONS;    STAINLESS STEELS;    STRAIN RATE;    STRESS CORROSION;    TRA;   

DOI  :  10.2172/972196
RP-ID  :  ANL/09-32
PID  :  OSTI ID: 972196
Others  :  TRN: US1001956

美国|英语

来源: SciTech Connect

【 摘 要 】

Cracking behavior of stainless steels specimens irradiated in the BOR-60 at about 320 C is studied. The primary objective of this research is to improve the mechanistic understanding of irradiation-assisted stress corrosion cracking (IASCC) of core internal components under conditions relevant to pressurized water reactors. The current report covers several baseline tests in air, a comparison study in high-dissolved-oxygen environment, and TEM characterization of irradiation defect structure. Slow strain rate tensile (SSRT) tests were conducted in air and in high-dissolved-oxygen (DO) water with selected 5- and 10-dpa specimens. The results in high-DO water were compared with those from earlier tests with identical materials irradiated in the Halden reactor to a similar dose. The SSRT tests produced similar results among different materials irradiated in the Halden and BOR-60 reactors. However, the post-irradiation strength for the BOR-60 specimens was consistently lower than that of the corresponding Halden specimens. The elongation of the BOR-60 specimens was also greater than that of their Halden specimens. Intergranular cracking in high-DO water was consistent for most of the tested materials in the Halden and BOR-60 irradiations. Nonetheless, the BOR-60 irradiation was somewhat less effective in stimulating IG fracture among the tested materials. Microstructural characterization was also carried out using transmission electron microscopy on selected BOR-60 specimens irradiated to {approx}25 dpa. No voids were observed in irradiated austenitic stainless steels and cast stainless steels, while a few voids were found in base and grain-boundary-engineered Alloy 690. All the irradiated microstructures were dominated by a high density of Frank loops, which varied in mean size and density for different alloys.