About this Abstract |
| Meeting |
Materials in Nuclear Energy Systems (MiNES) 2025
|
| Symposium
|
Materials in Nuclear Energy Systems (MiNES) 2025
|
| Presentation Title |
Impact of Post-Irradiation Annealing on Mechanical Properties and Microstructure of High Fluence RPV Steel and Weldments |
| Author(s) |
Timothy G. Lach, Mikhail Sokolov, Kun Wang, Kyle Everett, Xiang (Frank) Chen |
| On-Site Speaker (Planned) |
Timothy G. Lach |
| Abstract Scope |
The reactor pressure vessel (RPV) is one of the largest and most critical components in light water reactors (LWRs) and is the primary lifetime-limiting component due to its size and costs to replace. The RPV steels are low alloy steels containing small additions of Ni, Mn, and Mo as alloying elements for various performance improvements, and Cu, P, and Si as impurities. Life-limitation of the RPV arises from embrittlement and hardening caused by irradiation at reactor operating temperatures and is manifested as an increase in the ductile-to-brittle-transition temperature and decrease in upper shelf energy. This embrittlement is a result of high-density precipitation of nanometer-sized Mn-Ni-Si-rich clusters and Cu-rich clusters, with their size, number density, and composition depending on the concentration in the steel and the irradiation dose and temperature. Post-irradiation annealing is a promising option to dissolve the clusters and recover the fracture toughness of the RPV steel and weldments. Here, we report on the microstructural characterization and mechanical behavior before and after post-irradiation annealing of high fluence (1.9×10^20 n/cm2; E>1MeV) RPV steel and weldment harvested from the surveillance capsule of the Palisades nuclear power plant. Using transmission electron microscopy and atom probe tomography combined with mechanical testing, the extent of dissolution of precipitates and change in mechanical behavior will be analyzed as a function of annealing time and temperature. The analysis will provide insights into the feasibility of using post-irradiation annealing to recover fracture toughness of RPV after high fluence radiation and to extend the LWR powerplant lifetimes. |
| Proceedings Inclusion? |
Undecided |