Internal Flaws in the Silicon Carbide Coating of Fuel Particles for High-Temperature Gas-Cooled Reactors

Internal flaws in the silicon carbide (SiC) coating of fuel particles have been characterized. The internal flaws of the SiC coating were seen as external discolored spots. The porous flaws formed circumferentially during SiC deposition. These flaws may have a harmful effect on the mechanical integrity and the diffusion barrier of the particle. The SiC coating experiments were performed under systematically selected conditions to study the mechanism of flaw formation. The most important factor influencing flaw formation was found to be the mode of particle fluidization. Internal flaws were eliminated from the particles fabricated in a mass-production coater by controlling particle fluidization.