Behavior of Binder Materials in Graphite Matrix Powder for HTGR Fuel Compact

摘要

The fuel element for HTGR is manufactured by mixing coated fuel particles with matrix graphite powder and forming into either pebble type or cylindrical type compacts depending on their use in different HTGR cores.[1] The coated fuel particle, the so-called TRISO particle, consists of 500-μm spherical UO_2 particles coated with the low density buffer Pyrolytic Carbon (PyC) layer, the inner and outer high density PyC layer and SiC layer sandwiched between the two inner and outer PyC layers. The coated TRISO particles, after overcoating with a finer portion of matrix graphite powder, are mixed with a matrix graphite powder properly prepared and pressed into a spherical shape or a cylindrical compact, and then finally heat-treated at about 1900℃. These fuel elements can have different sizes and forms of compact.