Molecular Dynamics Studies of Anisotropy in Grain Boundary Energy and Mobility in UO₂

Nuclear energy is a proven large-scale, emission-free, around-the-clock energy source. As part of improving the nuclear energy efficiency and safety, a significant amount of effort is being expended to understand how the microstructural evolution of nuclear fuels affects the overall fuel performance. Grain growth is an important aspect of microstructural evolution in nuclear fuels because grain size can affect many fuel performance properties. In this work, the anisotropy of grain boundary energy and mobility, which are two important properties for grain growth, is examined for the light water reactor fuel uranium dioxide (UO₂) by molecular dynamics simulations. The dependence of these properties on both misorientation angle and rotation axis is studied. The anisotropy in grain boundary energy is found to be insignificant in UO₂. However, grain boundary mobility shows significant anisotropy. For both 20º and 45º misorientation angles, the anisotropy in grain boundary mobility follows a trend of M₁₁₁>M₁₀₀>M₁₁₀, consistent with previous experimental results of face-centered-cubic metals. Evidences of grain rotation during grain growth are presented. The rotation behavior is found to be very complex: counterclockwise, clockwise, and no rotation are all observed.

Name thesis:degree_name

M.S.

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Materials Science and Engineering

Department dc:contributor.department

Materials Science and Engineering

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

2019

Author dc:creator

• French, Jarin C.

Chair dc:contributor.committeechair

• Bai, Xianming

Committee members dc:contributor.committeemember

• Cai, Wenjun
• Corcoran, Sean G.

• Grain boundary energy
• Grain boundary mobility
• Anisotropy
• Uranium dioxide
• Molecular dynamics

Statement dc:rights

• Creative Commons Attribution-NoDerivatives 3.0 United States

Licence dc:rights.uri

• http://creativecommons.org/licenses/by-nd/3.0/us/

Language dc:language.iso

en_US

Handle dc:identifier.uri

http://hdl.handle.net/10919/89643

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/89643