SINTERED UO2 FUELS BY FIELD ASSISTED SINTERING TECHNOLOGY – ACCIDENT TOLERANCE AND FUEL PERFORMANCE MODELING

The advanced ceramic fuel development program is exploring revolutionary ceramic fuels with the potential of “game-changing” impact on reactor operation & response to beyond design scenario. Key properties of advanced fuels include high thermal conductivity, oxidation resistance, high temperature mechanical properties, and thus improved accident tolerance. Composite ceramic fuels possess distinct advantages to fulfill these key requirements. On the other hand, the US Nuclear Energy Advanced Modeling and Simulation (NEAMS) program is developing science-based next generation fuel performance modeling capability in order to facilitate the predictive capability of nuclear fuel performance and assist the design and analysis of reactor systems. Critical experimental data are needed to validate MARMOT models, particularly on effective thermal transport, fracture behavior and grain growth kinetics. The fabrication of sintered fuel pellets with well-controlled microstructure is prerequisite to establish the correlation of the microstructure features and fuel behavior.

In this talk, recent advancements of using field-assisted sintering technologies, specifically spark plasma sintering (SPS), in fabricating advanced fuels and engineering fuel matrix as the target systems will be reviewed. The fuel behaviors are characterized with the focus on the thermal-mechanical properties and accident tolerance. Composite UO₂ fuels are fabricated in which heterogeneous secondary phases are used as the additives to improve thermal conductivity and mechanical properties of the composite. The monolithic UO₂ fuels are also fabricated with by SPS with well controlled microstructure, grain size and porosity across multiple length scales from nano-metered to micron-sizes. The impacts of the microstructure on the thermal-mechanical properties, oxidation behavior and grain growth kinetics are discussed within the context of the MARMOT modeling.