NSUF 16-802: Microstructural Characterization of Archival Surveillance Steels from the Advanced Test Reactor (ATR-2) Neutron Irradiation Experiment
This proposal covers characterization of a number of different RPV surveillance alloys by scanning/transmission electron microscopy. These steels were irradiated to a fluence of ˜ 1.4x10^20 n/cm2 at ˜ 290°C in the UCSB ATR-2 experiment. The steels have variations in Cu, Ni, Mn and Si contents, as shown in Table 1 in the attached proposal narrative. S/TEM studies will help to quantify the precipitates that formed under irradiation and will help to link to the observed changes in mechanical properties, which have already been measured. Resolving these flux effects from higher flux test reactor databases is critical to reliably predicting TTS in much lower RPV fluxes. All essential equipment is available in the ORNL Low Activation Materials Development and Analysis (LAMDA) laboratory. This includes a dual-beam FIB and FEI Talos S/TEM to characterize the matrix of surveillance steels in Table 1 from the proposal narrative. S/TEM has been shown to accurately identify the precipitate volume fraction, size, number density and composition. The Talos’s precise EDS signal detection capabilities allows the high resolution chemical mapping of the precipitates. We will also attempt to identify Cu-MNSPs core-shell and core shell appendage structures to gain a thorough understanding of LBPs formation mechanisms.
A particular analysis focus post-S/TEM will be on microstructural comparisons to previous test reactor irradiations and mechanical property data from extensive surveillance programs to characterize the effect of a wide range of flux and fluence on the volume fraction, number density, average size, composition and character of precipitates and defect-solute complexes that form under irradiation.
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 of MNSPs and carry out compositional mapping of precipitates as well as dislocation loop densities.
2) Examine and quantify segregation of Cu/Ni/Mn/Si/P to microstructural features such as grain boundaries and dislocation loops.
These experimental objectives will be achieved within 6 months of the date of the award. The expected period to finish FIB sample preparation is 2 months. S/TEM Talos will be scheduled during this time period as FIB electron-transparent samples become available. Data analysis will be performed over the next several months with assistance from ORNL technicians and staff scientists.
Additional Info
| Field | Value |
|---|---|
| Abstract | This proposal covers characterization of a number of different RPV surveillance alloys by scanning/transmission electron microscopy. These steels were irradiated to a fluence of ˜ 1.4x10^20 n/cm2 at ˜ 290°C in the UCSB ATR-2 experiment. The steels have variations in Cu, Ni, Mn and Si contents, as shown in Table 1 in the attached proposal narrative. S/TEM studies will help to quantify the precipitates that formed under irradiation and will help to link to the observed changes in mechanical properties, which have already been measured. Resolving these flux effects from higher flux test reactor databases is critical to reliably predicting TTS in much lower RPV fluxes. All essential equipment is available in the ORNL Low Activation Materials Development and Analysis (LAMDA) laboratory. This includes a dual-beam FIB and FEI Talos S/TEM to characterize the matrix of surveillance steels in Table 1 from the proposal narrative. S/TEM has been shown to accurately identify the precipitate volume fraction, size, number density and composition. The Talos’s precise EDS signal detection capabilities allows the high resolution chemical mapping of the precipitates. We will also attempt to identify Cu-MNSPs core-shell and core shell appendage structures to gain a thorough understanding of LBPs formation mechanisms. A particular analysis focus post-S/TEM will be on microstructural comparisons to previous test reactor irradiations and mechanical property data from extensive surveillance programs to characterize the effect of a wide range of flux and fluence on the volume fraction, number density, average size, composition and character of precipitates and defect-solute complexes that form under irradiation. 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 of MNSPs and carry out compositional mapping of precipitates as well as dislocation loop densities. 2) Examine and quantify segregation of Cu/Ni/Mn/Si/P to microstructural features such as grain boundaries and dislocation loops. These experimental objectives will be achieved within 6 months of the date of the award. The expected period to finish FIB sample preparation is 2 months. S/TEM Talos will be scheduled during this time period as FIB electron-transparent samples become available. Data analysis will be performed over the next several months with assistance from ORNL technicians and staff scientists. |
| Award Announced Date | 2016-12-16T07:45:49.423 |
| Awarded Institution | None |
| Facility | None |
| Facility Tech Lead | Kory Linton |
| Irradiation Facility | None |
| PI | Nathan Almirall |
| PI Email | [email protected] |
| Project Type | RTE |
| RTE Number | 802 |