NSUF 18-1176: Atom Probe Tomography Investigations of nm-Scale Precipitates in Reactor Pressure Vessel Steels in the UCSB Advanced Test Reactor (ATR-2) Neutron Irradiation Experiment
This proposal covers APT characterization of a set of key RPV alloys to build on a growing Small Angle X-Ray Scattering (SAXS), Small-Angle Neutron Scattering (SANS), XRD, and APT database. This work will continue to fill remaining gaps in composition and irradiation conditions not yet characterized. The unique combination of characterization tools (SANS, SAXS, XRD, APT) will provide vital insights into MNSPs including: volume fraction, size, number density, composition, crystal structure and magnetic character. The steels were primarily irradiated to a fluence of ˜ 1.4x1020 n/cm2 at Tirr ˜ 250°C in the UCSB ATR-2 experiment. Several past RTEs from UCSB characterized these same alloys with APT at Tirr ˜ 290°C. While the majority of LWRs operate at ˜ 290°C, the Tirr for others ranges down ˜ 250°C or lower. Understanding the effect of Tirr on precipitate formation is important for developing advanced thermo-kinetic models of precipitation. These results will then be compared with other UCSB databases covering a wide range of flux, fluence and alloy composition, including: APT, SAXS, SANS data from steels irradiated at 290°C at the same flux and fluence to isolate the role of Tirr. Overall, this project should be seen as programmatic sponsored work aimed at supporting the LWRSP RPV task and is an important contribution to the PI’s PhD thesis. The primary experimental objectives of this proposal include: 1) Measure volume fraction, size, number densities and precipitate compositions of MNSPs formed under irradiation at high fluence ˜ 1.4x1020 n/cm2 to fill in condition/composition gaps, including at Tirr ˜ 250°C. 2) Examine and quantify segregation of Ni/Mn/Si/P to microstructural features such as grain boundaries, dislocations and dislocation loops. These experimental objectives will be achieved within 6 months of the date of the award. The expected period to finish all FIB sample preparation is within one week. APT at CAES will be scheduled directly following this time period as APT needle samples become available. Data analysis will be performed over the next several months by PI.
Additional Info
| Field | Value |
|---|---|
| Abstract | This proposal covers APT characterization of a set of key RPV alloys to build on a growing Small Angle X-Ray Scattering (SAXS), Small-Angle Neutron Scattering (SANS), XRD, and APT database. This work will continue to fill remaining gaps in composition and irradiation conditions not yet characterized. The unique combination of characterization tools (SANS, SAXS, XRD, APT) will provide vital insights into MNSPs including: volume fraction, size, number density, composition, crystal structure and magnetic character. The steels were primarily irradiated to a fluence of ˜ 1.4x1020 n/cm2 at Tirr ˜ 250°C in the UCSB ATR-2 experiment. Several past RTEs from UCSB characterized these same alloys with APT at Tirr ˜ 290°C. While the majority of LWRs operate at ˜ 290°C, the Tirr for others ranges down ˜ 250°C or lower. Understanding the effect of Tirr on precipitate formation is important for developing advanced thermo-kinetic models of precipitation. These results will then be compared with other UCSB databases covering a wide range of flux, fluence and alloy composition, including: APT, SAXS, SANS data from steels irradiated at 290°C at the same flux and fluence to isolate the role of Tirr. Overall, this project should be seen as programmatic sponsored work aimed at supporting the LWRSP RPV task and is an important contribution to the PI’s PhD thesis. The primary experimental objectives of this proposal include: 1) Measure volume fraction, size, number densities and precipitate compositions of MNSPs formed under irradiation at high fluence ˜ 1.4x1020 n/cm2 to fill in condition/composition gaps, including at Tirr ˜ 250°C. 2) Examine and quantify segregation of Ni/Mn/Si/P to microstructural features such as grain boundaries, dislocations and dislocation loops. These experimental objectives will be achieved within 6 months of the date of the award. The expected period to finish all FIB sample preparation is within one week. APT at CAES will be scheduled directly following this time period as APT needle samples become available. Data analysis will be performed over the next several months by PI. |
| Award Announced Date | 2018-02-01T14:12:32.103 |
| Awarded Institution | None |
| Facility | None |
| Facility Tech Lead | Yaqiao Wu |
| Irradiation Facility | None |
| PI | Nathan Almirall |
| PI Email | [email protected] |
| Project Type | RTE |
| RTE Number | 1176 |