NSUF 18-1165: Elevated Temperature In-situ SEM micro compression of UO2
Micro compression pillars will be used to measure the yield stress and produce stress versus strain curves for UO2 in the temperature range from RT-700 ºC in order to increase the mechanical property database for the modeling of fuel. The micro compression pillars will be manufactured using a focused ion beam instrument on a single crystal of UO2. The use of a single crystal is desired for the measurements as it would remove the elastic anisotropy and porosity scatter of a polycrystalline UO2 sample. This removal allows an investigation into the intrinsic material scatter of the UO2 which is desirable for predictive modeling efforts. Having all of the pillars in a single crystal would give individual grain or subgrain properties which is a need in modeling efforts of UO2 fuel. In addition, having all of the pillars in a single orientation allows for direct comparison of the pillars at different temperatures. The micro compression testing will be performed with a Hyistron PI-88 system. After the micro compression testing is conducted the SEM/FIB system, at UC Berkeley will be used to manufacture TEM foils of the deformed pillars to evaluate the microstructure and deformation mechanisms. This would allow the ability to compare the deformation of the UO2 at room temperature and elevated temperature (~700 ºC). At room temperature, it is expected that UO2 will fail in brittle manner while at temperature there could some ductility in the UO2. The TEM foils with techniques such as transmission electron backscatter diffraction and scanning transmission electron microscopy which are available on the SEM/FIB system at UC Berkeley would allow for evaluation of the deformation of UO2 at the different temperatures. This mechanical and microstructural data collected will assist in the development of advanced fuel modeling in the MARMOT-BISON-MOOSE framework. The successful use of these techniques on the single crystal UO2 would allow for their use on irradiated fuel greatly reducing the volumes needed which would greatly reduce the dose to the worker while still gaining mechanical properties of the material. In addition, it would allow the ability to probe different regions of an irradiated fuel pellet or different grains in a polycrystalline UO2 pellet to increase the knowledge of the mechanical properties throughout the pellet. This proposal seeks to measure the mechanical properties of UO2 in the temperature range RT-700 ºC using small scale mechanical testing in order to increase the mechanical data for modeling efforts and develop new mechanical testing techniques for the investigation of actinide oxides. The above-proposed investigation will be conducted at the Berkeley NSUF facility utilizing the SEM/FIB and Hysitron PI-88 system. We request 6 days to manufacture the pillars and test them. The time will also be used to perform the T-EBSD and SEM-STEM on the foils prepared from deformed pillars.
Additional Info
| Field | Value |
|---|---|
| Abstract | Micro compression pillars will be used to measure the yield stress and produce stress versus strain curves for UO2 in the temperature range from RT-700 ºC in order to increase the mechanical property database for the modeling of fuel. The micro compression pillars will be manufactured using a focused ion beam instrument on a single crystal of UO2. The use of a single crystal is desired for the measurements as it would remove the elastic anisotropy and porosity scatter of a polycrystalline UO2 sample. This removal allows an investigation into the intrinsic material scatter of the UO2 which is desirable for predictive modeling efforts. Having all of the pillars in a single crystal would give individual grain or subgrain properties which is a need in modeling efforts of UO2 fuel. In addition, having all of the pillars in a single orientation allows for direct comparison of the pillars at different temperatures. The micro compression testing will be performed with a Hyistron PI-88 system. After the micro compression testing is conducted the SEM/FIB system, at UC Berkeley will be used to manufacture TEM foils of the deformed pillars to evaluate the microstructure and deformation mechanisms. This would allow the ability to compare the deformation of the UO2 at room temperature and elevated temperature (~700 ºC). At room temperature, it is expected that UO2 will fail in brittle manner while at temperature there could some ductility in the UO2. The TEM foils with techniques such as transmission electron backscatter diffraction and scanning transmission electron microscopy which are available on the SEM/FIB system at UC Berkeley would allow for evaluation of the deformation of UO2 at the different temperatures. This mechanical and microstructural data collected will assist in the development of advanced fuel modeling in the MARMOT-BISON-MOOSE framework. The successful use of these techniques on the single crystal UO2 would allow for their use on irradiated fuel greatly reducing the volumes needed which would greatly reduce the dose to the worker while still gaining mechanical properties of the material. In addition, it would allow the ability to probe different regions of an irradiated fuel pellet or different grains in a polycrystalline UO2 pellet to increase the knowledge of the mechanical properties throughout the pellet. This proposal seeks to measure the mechanical properties of UO2 in the temperature range RT-700 ºC using small scale mechanical testing in order to increase the mechanical data for modeling efforts and develop new mechanical testing techniques for the investigation of actinide oxides. The above-proposed investigation will be conducted at the Berkeley NSUF facility utilizing the SEM/FIB and Hysitron PI-88 system. We request 6 days to manufacture the pillars and test them. The time will also be used to perform the T-EBSD and SEM-STEM on the foils prepared from deformed pillars. |
| Award Announced Date | 2018-02-01T14:12:06.93 |
| Awarded Institution | None |
| Facility | None |
| Facility Tech Lead | Peter Hosemann |
| Irradiation Facility | None |
| PI | David Frazer |
| PI Email | [email protected] |
| Project Type | RTE |
| RTE Number | 1165 |