Study of Thorium Dioxide Nano-particle Sintering by Molecular Dynamics Simulations

• Main Authors: Wan-ChinChao, 趙婉琴
• Other Authors: Wen-Dung Hsu
• Format: Others
• Language: zh-TW
• Published: 2014
• Online Access: http://ndltd.ncl.edu.tw/handle/48570507540774572888

碩士 === 國立成功大學 === 材料科學及工程學系 === 102 === In recent times, thorium-based materials have regained interest as a nuclear fuel due to their unique characteristics such as abundant resource, long fuel cycles, high burn up, and improved waste form characteristics, etc. However, the higher sintering temperature (〉2200K) has hampered the commercialization of thorium dioxide fuel. To overcome the issue, molecular dynamics (MD) simulations is used to study the microstructure evolution of ThO2 nanoparticles during sintering at T=1800K-2200K below melting point. We used two sizes of ThO2 nanoparticles 3.36nm and 4.49nm in different crystal orientations, and the innovative three-dimensional fcc model was adopted to mimic the real sintering process. The effect of sintering temperature, porosity, the angle of particle reorientation, mean square displacement of Th and O in different regimes of ThO2 particle and grain growth were investigated. By the results, we found that the system densified very well as the particle size is small and as T≧1900K. Here we classify three governing sintering mechanisms: particle reorientation, contact plane adjustment and surface diffusion in different stages. The simulation results would provide useful information on the synthesis of ThO2 nuclear fuel pellet.