Title:

Quantum-Mechanical Calculations and Monte Carlo Simulation of the Thermodynamic Properties of Mixing for Tetravalent AO2 Nuclear Materials

Speaker:

Dr. Lindsay Shuller-Nickles

Affiliation:

Clemson University

When:

Monday, October 17, 2011 at 11:00:00 AM   Add to Calendar

Where:

Boggs Building, Room 3-47

Host:

Dr. Chaitanya Deo
chaitanya.deo@nre.gatech.edu

Abstract

Experimental and theoretical studies have been conducted on AIVO2 (AIV = Zr, Ce, Th, U) solid solutions to determine in-reactor performance based primarily on neutronic and thermal properties; however, the thermodynamic mixing properties of these solid solutions also have implications for fuel fabrication, in-reactor performance, and fuel stability. Atomic-scale measurements or simulations of cation ordering and the associated thermodynamic properties of such systems have yet to be determined. This study employs a combination of density-functional theory, Monte-Carlo methods, and thermodynamic integration to calculate thermodynamic properties of the ThxU1-xO2, ThxZr1-xO2, CexZr1-xO2, and CexTh1-xO2 binaries (ÄHmix, ÄGmix, ÄSmix). Phase diagrams are generated based on the ÄGmix and miscibility gaps are identified. The competitive kinetic hindrances derived from the strain caused by the lattice mismatch at the lamellae interfaces are estimated and compared with the tendency towards exsolution in order to fully understand the thermodynamics of the oxide binaries.

Biography

Dr. Shuller-Nickles recently joined the Environmental Engineering and Earth Science faculty at Clemson University after having completed her Ph.D. and post-doctoral work at University of Michigan in Materials Science and Engineering and Geological Sciences, respectively. Her research and teaching interests are in environmental mineralogy, nuclear fuels and waste forms, geochemistry, and computational materials science. She integrates computational and experimental techniques to evaluate the stability of nuclear materials and waste streams throughout the nuclear fuel cycle.