NSUF 19-1765: Temperature shift evaluation for G-phase nanocluster evolution in ferritic/martensitic alloys
The objective of this project is to validate the temperature shift requirements for irradiation-induced nanocluster evolution in three separate ferritic-martensitic alloys, as predicted by two unique nanocluster evolution calculation models. Ferritic/martensitic (F/M) alloys are leading candidates for structural and fuel cladding applications for advanced nuclear reactor designs due to their high strength and thermal conductivity. To date, studies evaluating nanocluster evolution in the commercial F/M alloys HCM12A and HT9 have exhibited variable nanocluster evolution of Cu-rich, Si-Mn-Ni-rich and Cr-rich nanoclusters after irradiation with protons, Fe2+ ions, or neutrons to otherwise common conditions of ~3dpa at 500°C. Recent analysis of F/M alloy T91 at the same irradiation conditions has demonstrated similar varying results in nanocluster evolution with the higher dose rate irradiation resulting is coarser nanocluster distribution. These trends suggest the need for an experimental temperature shift when irradiating with charged particles at higher dose rates to accurately emulate neutron irradiation.
Two different calculation models are developed to simulate irradiation-induced nanocluster evolution in these alloys. We first use an existing cluster dynamics (CD) model to describe nucleation and coarsening of Si-Mn-Ni-rich nanoclusters in b.c.c. Fe-based alloys, previously shown to be successful with RPV steels and prior proton irradiations of T91 at 400°C. In our study, we only modify the model parameters to reflect our irradiation conditions (Fe2+, proton, or neutron irradiation at 500°C) and the alloy compositions of T91, HCM12A and HT9, respectively, from our experiments. As with the previous studies, CD reasonably simulates the nanocluster evolution up to 3 dpa, predicting larger nanoclusters with self-ion irradiation at a higher dose rate. Through evaluation of temperature sensitivity, the model also predicts that Fe2+ irradiation at a revised temperature of 360–380°C would result in a close emulation of the neutron irradiation result at 500°C, suggesting a negative temperature shift is merited for Fe2+ irradiation. This negative temperature shift is corroborated [4] with another model based on rate theory and the work of Nelson, Hudson, and Mazey (NHM), which also simulates experimental results well and predicts a negative temperature shift for higher dose rate irradiation.
This project aims to conduct one self-ion irradiation with 5 MeV Fe2+ ions to 3 dpa at 370°C on the commercial F/M alloys T91, HCM12A and HT9 at the Michigan Ion Beam Laboratory (MIBL). Following irradiation, post irradiation examination (PIE) is planned to characterize microstructure and nanocluster irradiation evolution, enabling direct comparison with previously analyzed specimens irradiated with Fe2+ ions or fast neutrons to 3 dpa at 500°C. This comparison will allow us to verify any temperature shift requirements for nanocluster irradiation evolution and validate the efficacy of the two calculation models developed. Improved confidence in these models will provide valuable tools to aid nanofeatured alloy development for advanced nuclear reactor environments. The total project including irradiation and PIE is expected to take 6-9 months.
Допълнителна информация
| Поле | Стойност |
|---|---|
| Abstract | The objective of this project is to validate the temperature shift requirements for irradiation-induced nanocluster evolution in three separate ferritic-martensitic alloys, as predicted by two unique nanocluster evolution calculation models. Ferritic/martensitic (F/M) alloys are leading candidates for structural and fuel cladding applications for advanced nuclear reactor designs due to their high strength and thermal conductivity. To date, studies evaluating nanocluster evolution in the commercial F/M alloys HCM12A and HT9 have exhibited variable nanocluster evolution of Cu-rich, Si-Mn-Ni-rich and Cr-rich nanoclusters after irradiation with protons, Fe2+ ions, or neutrons to otherwise common conditions of ~3dpa at 500°C. Recent analysis of F/M alloy T91 at the same irradiation conditions has demonstrated similar varying results in nanocluster evolution with the higher dose rate irradiation resulting is coarser nanocluster distribution. These trends suggest the need for an experimental temperature shift when irradiating with charged particles at higher dose rates to accurately emulate neutron irradiation. Two different calculation models are developed to simulate irradiation-induced nanocluster evolution in these alloys. We first use an existing cluster dynamics (CD) model to describe nucleation and coarsening of Si-Mn-Ni-rich nanoclusters in b.c.c. Fe-based alloys, previously shown to be successful with RPV steels and prior proton irradiations of T91 at 400°C. In our study, we only modify the model parameters to reflect our irradiation conditions (Fe2+, proton, or neutron irradiation at 500°C) and the alloy compositions of T91, HCM12A and HT9, respectively, from our experiments. As with the previous studies, CD reasonably simulates the nanocluster evolution up to 3 dpa, predicting larger nanoclusters with self-ion irradiation at a higher dose rate. Through evaluation of temperature sensitivity, the model also predicts that Fe2+ irradiation at a revised temperature of 360–380°C would result in a close emulation of the neutron irradiation result at 500°C, suggesting a negative temperature shift is merited for Fe2+ irradiation. This negative temperature shift is corroborated [4] with another model based on rate theory and the work of Nelson, Hudson, and Mazey (NHM), which also simulates experimental results well and predicts a negative temperature shift for higher dose rate irradiation. This project aims to conduct one self-ion irradiation with 5 MeV Fe2+ ions to 3 dpa at 370°C on the commercial F/M alloys T91, HCM12A and HT9 at the Michigan Ion Beam Laboratory (MIBL). Following irradiation, post irradiation examination (PIE) is planned to characterize microstructure and nanocluster irradiation evolution, enabling direct comparison with previously analyzed specimens irradiated with Fe2+ ions or fast neutrons to 3 dpa at 500°C. This comparison will allow us to verify any temperature shift requirements for nanocluster irradiation evolution and validate the efficacy of the two calculation models developed. Improved confidence in these models will provide valuable tools to aid nanofeatured alloy development for advanced nuclear reactor environments. The total project including irradiation and PIE is expected to take 6-9 months. |
| Award Announced Date | 2019-05-15T09:43:10.827 |
| Awarded Institution | None |
| Facility | None |
| Facility Tech Lead | Kevin Field, Yaqiao Wu |
| Irradiation Facility | Michigan Ion Beam Laboratory |
| PI | Matthew Swenson |
| PI Email | [email protected] |
| Project Type | RTE |
| RTE Number | 1765 |