Doping UO2 with aliovalent transition metals to increase grain size during sintering. The dopants segregates to grain boundaries (GBs) which cause local restructuring of GBs due to defects compensating mechanisms for charge balancing.

3D reconstructed microstructure (top row) and segmented porosity (bottom row) from X-ray tomography of U-10Zr fuel samples extracted at increasing radial distances: Center, Middle, Edge, and Fuel–Cladding interface. Each cube represents a 50 μm field of view. Segmented pore volumes (in blue) reveal changes in pore morphology and connectivity from the fuel center to the outer cladding interface, where larger, more interconnected porosity is observed near the edge and cladding.

Evolution of a Ni microcrystal’s Bragg peak during PWR coolant simulation. (A) Bragg peak cross sections are shown perpendicular to each axis. (B) First row: 3D phase isosurface evolution as visualized in ParaView. Second and third rows: Phase evolution at midsection slices in the ZX and YX planes, respectively. Dislocations are marked C–E with arrows indicating the direction of the phase spiral. An isometric view of the phase isosurface at 32.5 h is shown to the right of the phase plot, as rendered in ParaView.

Nickel microcrystal on SiO2/Si(001) support. Strain relaxation from X-ray beam exposure in reciprocal (top) and real (middle) space. The strain field energy (bottom) presents a quantitative decrease of the strain field inside the crystal.

Time evolution of a NiCo microcrystal in PWR coolant chemistry. A screw dislocation is observed starting at 6 hours of exposure.

Research Overview

Nuclear energy has become essential to decarbonize the world’s economy. Advanced reactors and propulsion concepts are expected to operate at much higher temperatures and irradiation doses compared to the current fleet of light water reactors. Developing advanced materials that can satisfactorily perform for the reactor lifetime under these extreme conditions is critical for successful deployment of advanced reactors. Discovering and developing high-performance structural materials and accident-tolerant fuels remains a grand challenge. Our overarching research goal is to address this challenge by improving existing materials and engineering new ones using coupled experiments, atomistic simulations and data science in ways that provide atomic to mesoscale level understanding that informs the rational design of these materials while gaining mechanistic understanding of materials behavior under normal and off-normal reactor conditions.

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