Ying Chen University of Tokyo

Event Info

Title:  Computational Study of Defects Behavior in Ceramics Fuels

Date: Nov 3, 2008
Location: 3105 Etcheverry Hall
Time: 4-5pm

Abstract

It is well known that the performance of ceramics nuclear fuel is quite related to the defects behavior under irradiation. In UO2, one of most widely used fuel materials, a characteristic defective structure is found to be emerged after some complex processes under the high burn-up. This so called “Rim structure” induces swelling of the lattice then influences the burning effect and life of the fuel. To investigate the microscopic mechanism of the defective structure behavior in the ceramics fuel, computational study from first principles approach to molecular dynamics has been performed for . for UO2, as well as CeO2, a simulation materials of UO2 used in the accelerator experiments due to its similar structural and thermodynamic properties. These calculations revealed the origin of similarities and differences between these two systems from electronic structure level, and give an explanation on the nonstoichiometric features manifested in the phase diagrams of U-O and Ce-O based on point defects model. Further calculations on defect clusters clarified the ambiguousness remaining for long in the structure of nonstoichiometric UO2+x, proposed a new model of oxygen cluster stability. Meanwhile, the molecular dynamics is applied to large scale simulation of planer defect included one of main fission products, Xe atoms. It showed that a planar distribution is meta-stable for Xe atoms under thermodynamic perturbations.

Speaker Biography

Dr. Ying Chen (Ph. D., Quantum Engineering and System Science, The University of Tokyo, 1996; M. S., Solid States Physics, 1986, Beijing University of Science and Technology; B. S. Physics, Beijing Normal University, 1982) works as an Associate Professor at the Department of Quantum Engineering and Systems Science, School of Engineering, The University of Tokyo. Her main research filed is the theoretical research of materials design, including studying materials properties (phase stability, phase equilibria of alloys, irradiation effect of nuclear materials, etc.) by first principles calculation combined with statistical and thermodynamic method, investigating regularities among crystal structure, properties and materials and the constitutional elements so as to discovery new materials by integrating data mining and physical modeling.