Today, pyrocarbon (PyC) is the most common material used for the coating of nuclear fuel particles for the fuel elements of the high-temperature gas-cooled reactor. During recent years, many procedures have been developed for this material that have yielded a broad spectrum of information and have thereby improved knowledge of PyC. The characterization methods that are suitable for out-line quality control include coating layer density determination by sink float techniques, coating layer thickness by x-ray projection or by contact microscopy, and orientation anisotropy. Many other techniques are available for laboratory use.
