Optimizing HTGR Spherical Fuel Element Manufacture Technology through Dispersion Fuel Press Processing

Abstract

This thesis presents an in-depth analysis of the dispersion fuel press process for High- Temperature Gas-Cooled Reactors (HTGRs), focusing on optimizing key parameters that influence the quality and performance of HTGR fuel elements. Through comprehensive simulations performed utilizing COMSOL Multiphysics(FEM), this study systematically investigates the effects of pressing pressure and TRISO-coated particle count on the stress during the pressing process of spherical fuel elements. The research is structured into two main phases. The first phase examines the impact of applying varying pressures (20 to 35 MPa) on graphite powder within a rubber mold, emphasizing the necessity of achieving uniform compaction and material integrity. The second phase extends the investigation to incorporating TRISO-coated particles, analyzing how varying counts of these particles (ranging from 8000 to 20000) affect stress distri- bution, displacement, and volumetric strain within the fuel spheres. These simulations provide critical insights into optimizing the dispersion fuel press process, highlighting the balance between pressure application and particle count for enhancing fuel element fabrication. Key findings reveal that precise control and uniform application of pressure are cru- cial for ensuring the desired compaction and structural integrity of fuel spheres. Moreover, the study demonstrates that an optimized distribution of TRISO particles significantly in- fluences the mechanical behavior and resilience of the fuel elements, offering pathways to improve fuel performance and reactor efficiency. The research outcomes contribute valuable guidelines for the design, optimization, and manufacturing of HTGR fuel ele- ments, proposing advancements that could enhance the safety, efficiency, and reliability of nuclear reactors. This thesis underscores the importance of meticulous parameter optimization in HTGR fuel fabrication, providing a foundation for future research and development in nuclear fuel technology. By advancing our understanding of the dispersion fuel press process, this work aims to contribute to the nuclear energy sector’s efforts to develop safer, more efficient, and sustainable reactors.