TEM/STEM observation of ZrC-coating layer for advanced high-temperature gas-cooled reactor fuel

Aihara, Jun ; Ueta, Shohei   ; Yasuda, Atsushi; Ishibashi, Hideharu; Takayama, Tomoo; Sawa, Kazuhiro; Motohashi, Yoshinobu*

Japan Atomic Energy Agency (JAEA) has started to study and develop ZrC coated fuel particles for advanced high temperature gas cooled reactors. This paper mainly focuses on the microstructures of the ZrC and isotropic dense pyrolytic carbon (PyC) coating layer produced in the early stage of the project. The structure of free carbon region in the ZrC coating layer appears to be such that c-plane was along with the ZrC grain boundary. It appears that the existence of the free carbon phase, especially with such structure, deteriorates the fission product (FP) retention performance in addition to the mechanical strength of ZrC. The PyC coating layer appears to be a medium-range ordered amorphous structure.