THE STUDY ON PYROLYTIC CARBON POWDER IN THE COATING PROCESS OF FUEL PARTICLE FOR HIGH-TEMPERATURE GAS-COOLED REACTOR

摘要

The R&D of coating process of fuel particles is one of the most important key technologies in the research work of high-temperature gas-cooled reactor (HTGR). A safe and reliable coating process is expected and related to the prospect of large-scale utilization of nuclear energy. The related research of the carbon black powder which is the main byproduct generated in the coating process is important, because it relates to the impact of coating process on the surrounding environment and is also helpful to understand the deposit mechanism of PyC (pyrolytic carbon) layer coated on the fuel particle. In the present study, the microstructure of the pyrolytic carbon powder were systemati-cally investigated by scanning electron microscope (SEM), trans-mission electron microscopy (TEM), laser Raman spectroscopy and particle size analysis (PSA). It can be found that the car-bon powder in the cyclone separator is composed of the nano-spherical particles with the diameter of about 50nm. The ring-layered nano-structured carbon particles could be found from the electron micrographs. The comparison between Raman spectra of carbon powder and pyrolytic carbon coated on the fuel par-ticle showed that the droplet deposit mechanism was suitable to explain the PyC deposition process. The nano-particles agglom-erate into the irregular floc and the diameters of the stable par-ticle clusters are mainly 1 μm and 10 μm. The disposal methods of carbon black powder are also discussed.