NSUF 15-565: Atom probe tomography evaluation of irradiated and annealed RPV surveillance specimens from the R. E. Ginna reactor
Embrittlement of reactor pressure vessel (RPV) steels by irradiation is a critical issue that is accepted to be the limiting factor for plant life of light-water reactors (LWRs). The primary objective of the DOE Light-Water Reactor Sustainability (LWRS) Program RPV task is the development of robust predictions of transition temperature shifts (TTS) at high neutron fluences (E > 1 MeV) pertinent to pressurized water reactor (PWR) plant operation up to 80 years. Surveillance specimens from the Westinghouse 2-loop PWR reactor, R. E. Ginna (Ginna) that has been operating for ~ 40 years (30.5 effective full power years, EFPY) are key samples due to their high fluence irradiation.Embrittlement of RPV steels is known to occur due to microstructural evolution in the form of copper-enriched, or Mn-Ni-Si precipitates. In high nickel materials, the so-called late blooming phases associated with the Mn-Ni-Si precipitates that form at high fluences are of particular interest. Atom probe tomography is a technique ideally suited to the study of these precipitates, due to their nanoscale size, the chemical sensitivity and the role of solutes, particularly Cu and Ni. To mitigate the effect of these nanoscale precipitates, RPVs may be subjected to an annealing process of 450 °C for 168 hours to force the precipitate solutes back into solid solution and recover the fracture toughness of the material. These annealing conditions are predicated on historical data and it is as yet unknown if this is sufficient for high fluence irradiated materials.The proposed project seeks to characterize surveillance specimens following irradiation and annealing to examine any microstructural features such as Cu and/or Ni-Mn-Si precipitates. This information will then be used to further develop plant life extension models, thereby improving the current state-of-the-art knowledge base, and providing information that may directly impact plant life extension in operating LWR power plants.
Additional Info
| Field | Value |
|---|---|
| Abstract | Embrittlement of reactor pressure vessel (RPV) steels by irradiation is a critical issue that is accepted to be the limiting factor for plant life of light-water reactors (LWRs). The primary objective of the DOE Light-Water Reactor Sustainability (LWRS) Program RPV task is the development of robust predictions of transition temperature shifts (TTS) at high neutron fluences (E > 1 MeV) pertinent to pressurized water reactor (PWR) plant operation up to 80 years. Surveillance specimens from the Westinghouse 2-loop PWR reactor, R. E. Ginna (Ginna) that has been operating for ~ 40 years (30.5 effective full power years, EFPY) are key samples due to their high fluence irradiation.Embrittlement of RPV steels is known to occur due to microstructural evolution in the form of copper-enriched, or Mn-Ni-Si precipitates. In high nickel materials, the so-called late blooming phases associated with the Mn-Ni-Si precipitates that form at high fluences are of particular interest. Atom probe tomography is a technique ideally suited to the study of these precipitates, due to their nanoscale size, the chemical sensitivity and the role of solutes, particularly Cu and Ni. To mitigate the effect of these nanoscale precipitates, RPVs may be subjected to an annealing process of 450 °C for 168 hours to force the precipitate solutes back into solid solution and recover the fracture toughness of the material. These annealing conditions are predicated on historical data and it is as yet unknown if this is sufficient for high fluence irradiated materials.The proposed project seeks to characterize surveillance specimens following irradiation and annealing to examine any microstructural features such as Cu and/or Ni-Mn-Si precipitates. This information will then be used to further develop plant life extension models, thereby improving the current state-of-the-art knowledge base, and providing information that may directly impact plant life extension in operating LWR power plants. |
| Award Announced Date | 2015-04-22T00:00:00 |
| Awarded Institution | None |
| Facility | None |
| Facility Tech Lead | Yaqiao Wu |
| Irradiation Facility | None |
| PI | Philip Edmondson |
| PI Email | [email protected] |
| Project Type | RTE |
| RTE Number | 565 |