Nuclear Science User Facilities 126 Figure 6 (label a) shows the as-cast microstructure of U-10Zr, which exhibits in-solution variation of U and Zr content. Figure 6 (label b) shows the rolled and annealed U-10Zr alloy exhibiting a typical lamellar microstructure.The irradiation-vehicle fabrication is currently underway.An example of a U-Zr foil that is loaded into a Zr specimen holder is pictured in Figure 7. Future Activities The irradiation vehicle is slated for irradiation in the BR2 reactor in the fall of 2019. Prior to this, multiple awarded rapid-turnaround experi- ments (RTEs) are scheduled.These RTEs include in situ neutron-diffraction experiments to investigate texture, crystallography, and microstrain evolu- tion, as well as phase transitions during thermal cycling. Following this experi- ment, in situ thermal treatments during transmission electron microscopy will be carried out on identical samples to investigate phase-transformation kinetics.This pre-irradiation character- ization will provide a reference point for the post-irradiation characterization of this fuel, as well as provide a more in-depth understanding of the crystal- lography and kinetics of the U-Zr and U-Mo fuel systems. Publications [1.] M.K. Meyer, J. Gan, J.F. Jue, D.D. Keiser, E. Perez,A.B. Robinson, D.M.Wachs, N.Woolstenhulme, G.L. Hofman,Y.S. Kim, “Irradiation performance of U-Mo monolithic fuel,” Nucl. Eng.Technol.Vol. 46 (2014), pp. 169–182. [2.] S. van den Berghe, P. Lemoine, “Re- view of 15 years of high-density lowenriched UMo dispersion fuel development for research reactors in Europe,” Nucl. Eng.Technol.Vol. 46 (2014), pp. 125–146. [3.] D.E. Janney, S.L Hayes, “Experi- mentally Known Properties of U-10Zr Alloys:A Critical Review,” Nucl.Technol.Vol. 203 (2018), pp. 109–128. [4.] G.L. Hofman, L.C.Walters,T.H. Bauer, “Metallic fast reactor fuels,” Prog. Nucl. Energy.Vol. 31 (1997), pp. 83–110. [5.] SCK-CEN, BR2 refurbishment operation, (2019) http://science. BR2_refurbishment. Figure 6. Scanning electron microscopy backscatter micrograph of U-Zr samples following fabrication from an (a) as-cast and (b) rolled and annealed foil. The dark regions are Zr-rich while the light regions are U-rich.