Microstructural development from interdiffusion and reaction between U Mo and AA6061 alloys annealed at 600° and 550 °C

Abstract

The U.S. Material Management and Minimization Reactor Conversion Program is developing low enrichment fuel systems encased in Al-alloy for use in research and test reactors. Monolithic fuel plates have local regions where the U-Mo fuel plate may come into contact with the Al-alloy 6061 (AA6061) cladding. This results in the development of interdiffusion zones with complex microstructures with multiple phases. In this study, the microstructural development of diffusion couples, U-7wt.%Mo, U-10wt.%Mo, and U-12wt.%Mo vs. AA6061, annealed at 600°C for 24 hours and at 550°C for 1, 5 and 20 hours, were analyzed by scanning electron microscopy with x-ray energy dispersive spectroscopy. The microstructural development and kinetics were compared to diffusion couples U-Mo vs. high purity Al and binary Al-Si alloys. The diffusion couples developed complex interaction regions where phase development was influenced by the alloying additions of the AA6061.

Observed Changes in As-Fabricated U-10Mo Monolithic Fuel Microstructures After Irradiation in the Advanced Test Reactor

“…8 At the U-10Mo/Al-6061 interface, phases can be present that contain U, Mo, Al, Mg, and/or Si. 9 Zr can also be present due to the presence of the diffusion barrier layer. 5 This paper describes the microstructural changes at some regions of interest during irradiation within samples characterized to date, produced using lab-oratory-scale fabrication methods that were not optimized.…”

Evaluation of Uranium-235 Measurement Techniques

“…Metallic uranium exhibits higher radiation tolerance in the high temperature (>775°C) γ-U phase with the body-centered cubic crystal structure (Perez et al 2016), which is more malleable and ductile than the low temperature orthorhombic-structure α-U phase. Alloying with 6-10% Mo stabilizes the γ-U phase as the material is quenched from high temperature.…”