Chemical and heat transport in uranium oxide

International Conference and Expo on Ceramics

August 17-18, 2015 Chicago, USA

Marius Stan1, Zhi-Gang Mei1, Anders D R Andersson2, John J Low1, Alexander Thompson3, Alejandro Lopez Bezanilla1, Christopher R Stanek2, Christopher M Wolveron3 and Peter B Littlewood1

Scientific Tracks Abstracts: J Material Sci Eng

Abstract :

Modern society has increasing energy needs that require new materials with significantly improved properties. Advanced
mathematical modeling and high performance computer simulation, coupled with experimental validation, contribute
to enhancing the understanding of the complex phenomena that occur in materials at multiple time and length scales. This
presentation reviews recent computational materials science results focused on improving the understanding of heat and chemical
(oxygen, fission products) transport in uranium oxide – a ceramic material of high importance for nuclear energy applications.
After a brief description of the multi-scale methodology – density functional theory (DFT+U), molecular dynamics (MD), and
continuum (FEM) methods – recent results capturing temperature effects and the impact of defects on oxygen diffusivity and
thermal conductivity of UO2 are discussed, with an emphasis on the complezxity of the physics and chemistry of the material.
The results show a strong driving force for oxygen interstitials to form clusters, wth significant impact on the properties of the
UO2 fluorite phase and neighboring compounds. The diffusion properties are a function of the cluster size, with the large clusters
exhibiting high mobility through a multi-step mechanism. Experimental validation is also examined, especially the need for
dedicated validation experiments. The presentation ends with a discussion of opportunities in the high-performance computing
space for improved simulations of heat and chemical species transport in ceramics in general, and in UO2 in particular.

Biography :

Marius Stan is the National Technical Director of the Nuclear Energy Advanced Modeling and Simulation (NEAMS) program. He is also a Senior Computational
Energy Scientist at Argonne National Laboratory, a Senior Fellow of the Computation Institute at University of Chicago, and a Senior Fellow of the Institute for
Science and Engineering at Northwestern University. His main research interests include multi-scale and multi-physics models and simulations of heat and mass
transport in ceramics and metals for energy applications.