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The Complexity and Challenges of Irradiation-Induced Phase Instability Phenomenon in Nuclear Power Plant Components

by Merezhko D A, Merezhko M S, Maxim N Gussev, Thomas M Rosseel, Francis Garner
Publication Type
Conference Paper
Book Title
20th International Conference on Environmental Degradation of Materials in Nuclear Power Systems-Water Reactors
Publication Date
Page Numbers
1 to 12
Publisher Location
Pittsburg, Pennsylvania, United States of America
Conference Name
20th International Conference on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors (EnvDeg)
Conference Location
Snowmass Village, Colorado, United States of America
Conference Sponsor
Conference Date

High energy irradiation by neutrons or ions of metastable austenitic 300-series steels appears to initiate formation of bcc-phases with different morphology and elemental composition compared to that of retained ferrite. Extensive formation of specific Fe-rich ferrite was observed on the grain boundaries of annealed Russian steel 12Cr18Ni10Ti, an analog of AISI 321, after irradiation in the center-core region of sodium-cooled BN-350 fast reactor (SFR) doses up to 57 dpa at ~1×10-6dpa/sec. The ferrite fraction determined from scanning electron microscopy (SEM) closely matched the magnetic fraction determined using a ferritscope confirmed by X-ray diffraction analysis and selected area diffraction patterns. Chemical composition of the secondary phases was determined by energy dispersive X-ray analysis using transmission electron microscope, showing Fe-rich ferrite domains. Fe-ion irradiation (2.3 MeV) was used to study the accumulation of ferrite and martensite phases at higher dpa rates. The very high etchability of these ferrite particles in alcohol-based solutions may signal a very high etching in hot water, leading to accelerated intergranular cracking, especially upon long-term exposure during extended plant lifetimes.