| 摘要 |
PROBLEM TO BE SOLVED: To provide a vitrification-solidification method for removing heat emitted from a radioactive substance when a fuel kernel is vitrified-and-solidified for the purpose of storing or disposing of the fuel kernel of a spent nuclear fuel waste, a vitrification-solidification method capable of avoiding an excessive thermal stress accumulated in the fuel kernel and a vitrification-solidification method capable of uniformly dispersing the fuel kernel in a vitrified melt. SOLUTION: A pebble is made by removing carbon/graphite matrix from the fuel kernel (26), coating with a glass layer a silicon carbide layer of the fuel kernel thus exposed (32) and dispersing it in the vitrified melt and vitrifying-and-solidifying it. The glass layer having a variable thermal expansion coefficient is made to have a thermal expansion coefficient equal to a thermal expansion coefficient of the vitrified melt and the silicon carbide layer adjacent to the glass layer (34 and 36). The glass layer coated on the fuel kernel has a softening temperature higher than that of the vitrified melt so that the glass can keep its state even if heat is radiated. The fuel kernel is made to have a specific gravity equal to that of the vitrified melt (50) so that the kernel is uniformly dispersed in the melt. COPYRIGHT: (C)2004,JPO
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