| Abstract: | An irradiation test using the uranium 10 wt.% zirconium (U-10Zr) alloy has been prepared for insertion in the Advanced Test Reactor (ATR) at Idaho National Laboratory (INL). The overall objective is to demonstrate the direct validation of microstructural evolution and thermal behavior models being developed for U-10Zr as part of the MARMOT code. The work reported here is part of a larger project enabled through the U.S. Department of Energy⁰́₉s Nuclear Energy University Program that is being performed in collaboration with the Nuclear Science User Facilities (NSUF). More specifically, while the larger project involves an ongoing irradiation campaign in ATR, this portion of the project included the preparation and characterization of alloy materials for testing and participating in the pre-irradiation characterization activities carried out by NSUF researchers. Once complete, pre- and post-irradiation data will be available at different material damage and burnup levels for model validation and direct comparison of changes in physical behavior and microstructural evolution. In summary, four U-10 Zr alloy types were prepared for this experiment. The first three types used depleted uranium (DU) and were prepared to have notably different initial microstructures: 1) annealed, 2) quenched, and 3) extruded. The fourth alloy was prepared at INL using 31 at.%high enriched uranium to create a parallel sample set. The intent is to characterize the microstructural evolution of the DU samples as a separate effects test whereas the HEU alloy will provide control data with actual nuclear fuel behavior. The alloys were machined by INL to form thin discs (4.8 mm x 0.4 mm) and very small whiskers (1mm x 0.3 mm) and placed into four irradiation capsules with identical sample counts from each type. The capsules are to be removed after four different irradiation cycles to provide low to high exposure/burnup rates to enable the observation of changes over time. Pre-irradiation characterizations were performed to document the following parameters for each alloy type before the onset of irradiation: 1) density, 2) electron microscopy, 3) Electron Probe Micro Analyzer (Wavelength Dispersive Spectroscopy and Energy Dispersive Spectroscopy), 4) Thermal Conductivity measurements, and 5) X-ray diffraction. The electronic version of this dissertation is accessible from https://hdl.handle.net/1969.1/197343 |
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