NSUF 18-1162: Pair distribution function analysis on recovery of irradiation induced defects in SiC
Recently, through an Advanced Fuel Campaign and NSUF RTE sponsored research efforts, high purity chemical vapor deposited SiC materials have been neutron irradiated over a range of fluences in the HFIR at ~80°C, and then the Wigner energy has been evaluated using a differential scanning calorimeter. Findings of this work show that the Wigner energy of SiC can be an issue; the stored energy release will exceed the specific heat depending on irradiation condition and heating rate. The objective of this proposed work is acquisition of critical experimental data to understand the microstructural source of this energy release. To do so, it is needed to understand what kind of structural changes occur during annealing. This study proposes to employ pair distribution function (PDF) analysis of XRD on neutron irradiated SiC samples with and without annealing at 700°C at NSLS II X-ray Powder Diffraction Beamline at Brookhaven National Laboratory (BNL). Synchrotron x-ray is needed to access the high values of momentum transfer (Q). Experimental PDF’s of high real-space resolution can be obtained that reveal changes in the short and medium range oredr. The 2D detector images will be reduced and converted to PDF (G(r): and then refined to extract quantitative, inter-atomic distance distributions (bond length), structural coherence length and the disorder as a function of neutron dose and annealing temperature. Comparison of the atomic structure before and after annealing will provide information on structural recovery by annealing. We will correlate such structural recovery and the previously obtained stored energy to understand the source of the energy release. Samples are currently in the LAMDA laboratory at the Oak Ridge National Laboratory, and they will be shipped to BNL. The specific designation of the irradiated samples are: PC-1-M1 (80°C/0.02 dpa), PC-2-M2 (80°C/0.1 dpa), PC-3-M3 (80°C/0.5 dpa), PC-4-M4 (80°C/2 dpa), and PC-5-M5(80°C/20 dpa) samples. It is anticipated that the duration of the testing will be less than six months.
Additional Info
| Field | Value |
|---|---|
| Abstract | Recently, through an Advanced Fuel Campaign and NSUF RTE sponsored research efforts, high purity chemical vapor deposited SiC materials have been neutron irradiated over a range of fluences in the HFIR at ~80°C, and then the Wigner energy has been evaluated using a differential scanning calorimeter. Findings of this work show that the Wigner energy of SiC can be an issue; the stored energy release will exceed the specific heat depending on irradiation condition and heating rate. The objective of this proposed work is acquisition of critical experimental data to understand the microstructural source of this energy release. To do so, it is needed to understand what kind of structural changes occur during annealing. This study proposes to employ pair distribution function (PDF) analysis of XRD on neutron irradiated SiC samples with and without annealing at 700°C at NSLS II X-ray Powder Diffraction Beamline at Brookhaven National Laboratory (BNL). Synchrotron x-ray is needed to access the high values of momentum transfer (Q). Experimental PDF’s of high real-space resolution can be obtained that reveal changes in the short and medium range oredr. The 2D detector images will be reduced and converted to PDF (G(r): and then refined to extract quantitative, inter-atomic distance distributions (bond length), structural coherence length and the disorder as a function of neutron dose and annealing temperature. Comparison of the atomic structure before and after annealing will provide information on structural recovery by annealing. We will correlate such structural recovery and the previously obtained stored energy to understand the source of the energy release. Samples are currently in the LAMDA laboratory at the Oak Ridge National Laboratory, and they will be shipped to BNL. The specific designation of the irradiated samples are: PC-1-M1 (80°C/0.02 dpa), PC-2-M2 (80°C/0.1 dpa), PC-3-M3 (80°C/0.5 dpa), PC-4-M4 (80°C/2 dpa), and PC-5-M5(80°C/20 dpa) samples. It is anticipated that the duration of the testing will be less than six months. |
| Award Announced Date | 2018-02-01T14:11:44.617 |
| Awarded Institution | None |
| Facility | None |
| Facility Tech Lead | Simerjeet Gill |
| Irradiation Facility | None |
| PI | TAKAAKI KOYANAGI |
| PI Email | [email protected] |
| Project Type | RTE |
| RTE Number | 1162 |