NSUF 18-1437: In-Situ Phase Analysis of Phase Transitions in U-(6, 10, 20, 30) wt%Zr Fresh Fuels.
Understanding the microstructural evolution of U-Zr samples, including phase stability, texture, crystal structure, and mechanical properties is crucial to tailor and accommodate these phenomena in our fuel systems and models. By utilizing the High-Pressure-Preferred Orientation (HIPPO) neutron diffractometer and the Spectrometer for Materials Research at Temperature and Stress (SMARTS) stations at Los Alamos Neutron Science Center (LANSCE), we will be able to quantify these features, specifically phases, phase fractions, texture, microstrain, dislocation density, and crystallite sizes, in fresh fuel and directly relate them to phenomena observed during irradiation. The first information being sought at HIPPO is the texture and crystal structure (phase) of these U-Zr samples. Due to a 95+%thickness reduction through rolling, a massive amount of stress and texture is introduced. The proposed samples are a 10mm cross section from cold-rolled foils of each of the four alloys. These samples would be characterized by neutron diffraction at HIPPO with the primary goal of texture analysis. Data would be collected continuously starting at room temperature and focus on intermediate phases (550, 640, 673, and 700 C) and evolution at 800 C. The 800 C sample will be held for two hours, matching the annealing process used in fabrication. We will then bring the samples back down to room temperature at a rate of 200C/hr, as this mimics the fabrication process and produces a microstructure similar to homogenized induction casted fuel rods. These four samples are estimated to take approximately 20 hours each, as such, four days are being requested at HIPPO. In conjunction with the HIPPO characterization, additional samples can be analyzed at SMARTS to assess phases, residual stresses, grain microstrain, dislocation density, and crystallite sizes. Lower fidelity texturing to avoid the long data collection times seen at HIPPO [4]. This study would focus in on U-10wt%Zr and U-30wt%Zr stress evolution throughout fabrication. The novel fabrication technique has multiple steps of interest including hot rolling, post hot rolling annealing for stress relief, cold rolling, and the final anneal. Acquiring a sample from each of these steps from both alloys would total eight samples. These would be used to understand texture evolution and recrystallization as a function of fabrication steps as seen in uranium-molybdenum by Brown, Okuniewski, et al. Overall, this work would directly provide insight into fabrication processes in the community, as well as aid in connecting modern experiments to those historically done on U-Zr. As a byproduct of the techniques being used, it will also be possible to observe the onset of various phase transformations, which is not well known in UZr. This data can be utilized to better understanding in the U-Zr binary phase diagram. Additionally, this data would serve as a baseline for future experiments on identical samples that are being irradiated as well as give a better understanding of how in-pile samples evolve at low burnups across these temperature ranges.
Additional Info
| Field | Value |
|---|---|
| Abstract | Understanding the microstructural evolution of U-Zr samples, including phase stability, texture, crystal structure, and mechanical properties is crucial to tailor and accommodate these phenomena in our fuel systems and models. By utilizing the High-Pressure-Preferred Orientation (HIPPO) neutron diffractometer and the Spectrometer for Materials Research at Temperature and Stress (SMARTS) stations at Los Alamos Neutron Science Center (LANSCE), we will be able to quantify these features, specifically phases, phase fractions, texture, microstrain, dislocation density, and crystallite sizes, in fresh fuel and directly relate them to phenomena observed during irradiation. The first information being sought at HIPPO is the texture and crystal structure (phase) of these U-Zr samples. Due to a 95+%thickness reduction through rolling, a massive amount of stress and texture is introduced. The proposed samples are a 10mm cross section from cold-rolled foils of each of the four alloys. These samples would be characterized by neutron diffraction at HIPPO with the primary goal of texture analysis. Data would be collected continuously starting at room temperature and focus on intermediate phases (550, 640, 673, and 700 C) and evolution at 800 C. The 800 C sample will be held for two hours, matching the annealing process used in fabrication. We will then bring the samples back down to room temperature at a rate of 200C/hr, as this mimics the fabrication process and produces a microstructure similar to homogenized induction casted fuel rods. These four samples are estimated to take approximately 20 hours each, as such, four days are being requested at HIPPO. In conjunction with the HIPPO characterization, additional samples can be analyzed at SMARTS to assess phases, residual stresses, grain microstrain, dislocation density, and crystallite sizes. Lower fidelity texturing to avoid the long data collection times seen at HIPPO [4]. This study would focus in on U-10wt%Zr and U-30wt%Zr stress evolution throughout fabrication. The novel fabrication technique has multiple steps of interest including hot rolling, post hot rolling annealing for stress relief, cold rolling, and the final anneal. Acquiring a sample from each of these steps from both alloys would total eight samples. These would be used to understand texture evolution and recrystallization as a function of fabrication steps as seen in uranium-molybdenum by Brown, Okuniewski, et al. Overall, this work would directly provide insight into fabrication processes in the community, as well as aid in connecting modern experiments to those historically done on U-Zr. As a byproduct of the techniques being used, it will also be possible to observe the onset of various phase transformations, which is not well known in UZr. This data can be utilized to better understanding in the U-Zr binary phase diagram. Additionally, this data would serve as a baseline for future experiments on identical samples that are being irradiated as well as give a better understanding of how in-pile samples evolve at low burnups across these temperature ranges. |
| Award Announced Date | 2018-05-17T11:07:37.72 |
| Awarded Institution | None |
| Facility | None |
| Facility Tech Lead | Tarik Saleh |
| Irradiation Facility | None |
| PI | Walter Williams |
| PI Email | [email protected] |
| Project Type | RTE |
| RTE Number | 1437 |