Berlin 2018 – scientific programme

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MM: Fachverband Metall- und Materialphysik

MM 37: Microstructure and Phase Transformations

MM 37.4: Talk

Wednesday, March 14, 2018, 12:30–12:45, TC 010

Oxide texture as cause and effect in the corrosion of zirconium fuel cladding - an atomistic simulation and electron microscopy study — •Maria S Yankova, Felicity Baxter, Alistair Garner, Philipp Frankel, and Christopher P Race — School of Materials, University of Manchester, UK

Oxidation of the Zr alloy fuel cladding in light water reactors is one of the key degradation mechanisms, limiting the amount of fuel burned. The structural and electronic properties of monoclinic and tetragonal zirconia grain boundaries strongly affect the transport of species through the oxide layer. Hence, changes in oxide texture and phase fractions under irradiation can significantly alter the oxidation kinetics. We are exploiting a combination of density functional theory (DFT) simulation, scanning precession electron diffraction in the transmission electron microscope (TEM) and novel Python-based texture analysis to obtain an improved mechanistic understanding of the oxide microstructure. We have performed DFT calculations of the stiffness of key lattice planes in bulk zirconia to explore the effect of transformational stresses on the growth of grain orientations strongly represented in our experimental texture maps. We have revealed a correlation between the metal-oxide interface and a preferred texture orientation previously hidden by conventional texture analysis. We have investigated the effect of irradiation-induced defects and alloying elements on the structural and electronic properties of representative oxide grain boundaries using DFT and have identified the dominant point defects that control the oxide growth in an electrochemical environment.