NUCLEAR-FUEL COATED PARTICLE DEVELOPMENT IN REACTOR-FUEL ELEMENT LABORATORIES OF UK-ATOMIC-ENERGY-AUTHORITY

The principles of the RFL pyrocarbon (PyC) and silicon carbide (SiC) coating processes, together with the experience of coating particles on a large scale-kernel batch sizes up to 25 kg-ave delineated. The understanding of the important parameters controlling deposition processes has led to optimum specifications for coater design and process route such that high sphericity is maintained throughout coating with a minimum spread in coat properties. More recent detailed investigations of process variables have identified the factors controlling PyC microstructure and the effect that coat defects and substrate shapes have on the ability of SiC to contain the gaseous fission products released by the fuel kernel during in-reactor operation.