b'Constituent RedistributionSimulating nuclear reactor temperature conditions enables faster and lower-in Nuclear Fuels cost discovery of new nuclear fuels.T he objective of this research was to develop and demonstrate an apparatus capable of generating a temperature gradient in a nuclear fuel pin that can be applied to any existing or novel nuclear fuel pin composition. Out-of-pile testing is a crucial component of understanding fuel behavior for both existing and new fuel compositions. Compared with a reactor experiment, an out-of-pile TOTAL APPROVED AMOUNT: experiment takes weeks or months instead of years and does not have the post- $1,065,000 over 3 years irradiation fuel handling requirements. To be as effective as possible, out-of-pile PROJECT NUMBER:testing needs to reproduce reactor conditions as closely as possible. To this end, 19A39-100 control of the temperature gradient has been incorporated into the experiments. This allows for the simulation of the temperature gradient found in nuclear fuel during PRINCIPAL INVESTIGATOR:irradiation and simulation of off-normal events. This research provides significant Michael Benson cost-savings over traditional reactor experiments and provides necessary information CO-INVESTIGATORS: to the nuclear fuel modeling effort.James King, INL Different compositions of uranium-molybdenum-titanium-zirconium (U-Mo-Ti-Zr) Pavel Medvedev, INL fuel alloys were characterized as part of this effort. This composition was chosen for Jinsuo Zhang, Virginia Tech multiple reasons, such as the fact that molybdenum and zirconium have significantly different redistribution behavior and the potential to maintain gamma () phase at the temperatures found in a fast reactor. As an example, the alloy U-1.5Mo-1.5Ti-7.0Zr (U-MT7Z) undergoes a phase transition from the alpha () phase to thephase on annealing above 675C. The phase transitions were determined by DSC, X-ray diffraction, and scanning electron microscopy. Understanding these phase transitions is fundamental to understanding metal alloy fuel behavior.TALENT PIPELINE:Weiqian Zhou, student at Virginia Polytechnic Institute and State UniversityHuali Wu, postdoc at Virginia Polytechnic Institute and State UniversityPUBLICATIONS:Zhuo, W., Y. Xie, M. T. Benson, J. B. Ge, R. D. Mariani, and J. Zhang, XRD and SEM/EDS characterization of two quaternary fuel alloys (U-2.5Mo-2.5Ti-5.0Zr and U-1.5Mo-1.5Ti-7.0Zr in wt. %) for fast reactors, Materials Characterization 170 (2020) 110696.Zhuo, W., H. Wu, Y. Xie, M. T. Benson, and J. Zhang, Solid-state phase transitions of two quaternary metallic fuel alloys (U-2.5Mo-2.5Ti-5.0Zr and U-1.5Mo-1.5Ti-7.0Zr in wt. %), Journal of Nuclear Materials 555 (2021) 153134.(a) X-ray diffraction results for U-MT7Z alloy, as quenched from high temperatures. (b) Scanning electron microscopy image of U-MT7Z annealed and quenched from 600C. (c) Scanning electron microscopy image of U-MT7Z annealed and quenched from 675C.59'