NSUF 22-4446: Effects of the fabrication technique and composition on microstructural evolution in uranium-molybdenum alloys neutron irradiated up to 1 dpa at low temperatures.
This proposed research will evaluate the effects of fabrication techniques (induction cast and rolled) and compositions on microstructural evolution in uranium-molybdenum (U-Mo) alloys irradiated up to 1 dpa at low temperatures. First, it is expected that the fractions of the decomposed phases will be higher in as-rolled U-10Mo alloy foil than in as-cast U-10Mo alloy at the same neutron fluence and irradiated temperature. It is hypothesized that a high concentration of dislocations, introduced by cold rolling, will provide additional stored energy, and more sites for the decomposed phases to be nucleated. Second, it is anticipated that a fraction of decomposed phases will increase as the neutron fluence and irradiation temperature increase in both the as-cast U-10Mo alloy and as-rolled U-10Mo alloy foil. It is hypothesized that more time will be required for the decomposed phases to be nucleated at comparatively low irradiation temperatures (150°C). Thus, the U-10Mo alloys irradiated at 350°C will have the higher fraction of the decomposed phases than those irradiated at 150°C. Furthermore, the density of irradiation-induced defects such as dislocation loops, which act as nucleation sites, will be increased as the neutron fluence increases to 1 dpa. Thus, more regions will exist for the decomposed phases to be nucleated. Third, it is expected that the lattice parameter of the γ-phase is expected to decrease with an increase in neutron fluence and irradiation temperature since interstitials have higher mobility than vacancies, created under irradiation. The number of interstitials annihilated at the sinks will be greater than that of vacancies, resulting in the lattice shrinkage. Lastly, it is expected that the fraction of the decomposed phases U-7Mo alloy foil will be greater than in U-10Mo alloy foil since Mo serves as the γ-phase stabilizer, slowing the phase transformation kinetics as shown in the time-temperature-transformation curves. It is proposed that synchrotron x-ray diffraction (XRD) and pair distribution function (PDF) experiments are conducted at the X-ray Powder Diffraction (XPD) beamline 28-ID-2 at National Synchrotron Light Source-ll. Synchrotron XRD will provide microstructural information such as phases present, phase fractions, lattice parameters, crystallite size, and microstrain with superior resolution, which a benchtop x-ray diffractometer is unable to do. Synchrotron PDF will also provide information on not only short-range and long-range disorder, but also lattice parameter with superior resolution. The proposed experiment timeline is 2 days (1 day for synchrotron XRD and 1 day for synchrotron PDF). This project will be the first attempt to understand and quantify the irradiation damage in U-Mo alloys of different fabrication methodologies and compositions with respect to the neutron fluence, irradiation temperature at the low fluence regime. This project will be useful to optimize nuclear fuel fabrication techniques (e.g. rolling versus casting) and compositions to enhance fuel lifetime and safety. The quantified results will also offer valuable input parameters into U-Mo fuel behavior models.
Additional Info
| Field | Value |
|---|---|
| Abstract | This proposed research will evaluate the effects of fabrication techniques (induction cast and rolled) and compositions on microstructural evolution in uranium-molybdenum (U-Mo) alloys irradiated up to 1 dpa at low temperatures. First, it is expected that the fractions of the decomposed phases will be higher in as-rolled U-10Mo alloy foil than in as-cast U-10Mo alloy at the same neutron fluence and irradiated temperature. It is hypothesized that a high concentration of dislocations, introduced by cold rolling, will provide additional stored energy, and more sites for the decomposed phases to be nucleated. Second, it is anticipated that a fraction of decomposed phases will increase as the neutron fluence and irradiation temperature increase in both the as-cast U-10Mo alloy and as-rolled U-10Mo alloy foil. It is hypothesized that more time will be required for the decomposed phases to be nucleated at comparatively low irradiation temperatures (150°C). Thus, the U-10Mo alloys irradiated at 350°C will have the higher fraction of the decomposed phases than those irradiated at 150°C. Furthermore, the density of irradiation-induced defects such as dislocation loops, which act as nucleation sites, will be increased as the neutron fluence increases to 1 dpa. Thus, more regions will exist for the decomposed phases to be nucleated. Third, it is expected that the lattice parameter of the γ-phase is expected to decrease with an increase in neutron fluence and irradiation temperature since interstitials have higher mobility than vacancies, created under irradiation. The number of interstitials annihilated at the sinks will be greater than that of vacancies, resulting in the lattice shrinkage. Lastly, it is expected that the fraction of the decomposed phases U-7Mo alloy foil will be greater than in U-10Mo alloy foil since Mo serves as the γ-phase stabilizer, slowing the phase transformation kinetics as shown in the time-temperature-transformation curves. It is proposed that synchrotron x-ray diffraction (XRD) and pair distribution function (PDF) experiments are conducted at the X-ray Powder Diffraction (XPD) beamline 28-ID-2 at National Synchrotron Light Source-ll. Synchrotron XRD will provide microstructural information such as phases present, phase fractions, lattice parameters, crystallite size, and microstrain with superior resolution, which a benchtop x-ray diffractometer is unable to do. Synchrotron PDF will also provide information on not only short-range and long-range disorder, but also lattice parameter with superior resolution. The proposed experiment timeline is 2 days (1 day for synchrotron XRD and 1 day for synchrotron PDF). This project will be the first attempt to understand and quantify the irradiation damage in U-Mo alloys of different fabrication methodologies and compositions with respect to the neutron fluence, irradiation temperature at the low fluence regime. This project will be useful to optimize nuclear fuel fabrication techniques (e.g. rolling versus casting) and compositions to enhance fuel lifetime and safety. The quantified results will also offer valuable input parameters into U-Mo fuel behavior models. |
| Award Announced Date | 2022-06-14T07:24:44.667 |
| Awarded Institution | None |
| Facility | None |
| Facility Tech Lead | Alina Zackrone, Simerjeet Gill |
| Irradiation Facility | None |
| PI | Maria Okuniewski |
| PI Email | [email protected] |
| Project Type | RTE |
| RTE Number | 4446 |