Abstract
Irradiation at PWR-relevant temperatures leads to multiple material degradation modes, including second-phase formation. It is known that formation of irradiation-induced bcc-ferrite can occur within austenite grains due to the tendency of nickel to segregate near the grain boundaries or void surfaces. In addition to affecting mechanical properties, ferrite may also affect cracking and corrosion behavior in water coolant, especially if the ferrite forms on grain boundaries. This work presents new high-fluence data derived from the BN-350 fast reactor to examine the potential for ferrite formation on grain boundaries in PWRs. The very low (<300°C) inlet temperature of BN-350 allows examination at PWR-relevant temperatures directly. When combined with several recent data sets at lower PWR-relevant dpa rates from BOR-60, which has a slightly higher (320-330°C) inlet temperature, it appears that very large amounts of ferrite can form on grain boundaries at temperatures and dose rates characteristic of PWR internals, allowing the possibility that a new degradation mechanism may assert itself at beyond-life-extension conditions, moving from previously second-order importance to a first-order concern at higher exposure levels.
Original language | English |
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Pages | 615-624 |
Number of pages | 10 |
State | Published - 2019 |
Event | 19th International Conference on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors, EnvDeg 2019 - Boston, United States Duration: Aug 18 2019 → Aug 22 2019 |
Conference
Conference | 19th International Conference on Environmental Degradation of Materials in Nuclear Power Systems - Water Reactors, EnvDeg 2019 |
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Country/Territory | United States |
City | Boston |
Period | 08/18/19 → 08/22/19 |
Funding
This research was supported by the Ministry of Education and Science in the Project № АР 05130527.