CERAMIC COATED PARTICLES FOR SAFE OPERATION IN HTRS AND IN LONG- TERM STORAGE

摘要

The fully ceramic core of a High-Temperature Gas-Cooled Reactor (HTR) consists of graphite internals and graphitic fuel elements that contain coated particles. These are fissile kernels that are surrounded by several coating layers. In BISO particles, the coating consists of a buffer layer and a dense pyrocarbon layer, in the TRISO particles there is a SiC interlayer interspersed between two dense pyrocarbon layers. While coatings originally had only been introduced for the handling in the fuel, they have been optimized in the meantime to withstand operational gas pressures, to retain fission products generated during irradiation and to keep them inside in accidents. The latest development showed the dense coating layers also to be efficient in long-term storage of HTR fuel.