| 摘要 |
1,130,111. Fuel elements. COMMISSARIAT A L'ENERGIE ATOMIQUE. 14 Jan., 1966 [21 Jan., 1965], No. 1934/66. Heading G6C. A spherical fuel element for a pebble-bed reactor is made by moulding a paste comprising a mixture of particles of enriched uranium dioxide and graphite together with a binding agent. The moulding produces a cylindrical fuel kernel which is rendered impermeable by a heating operation in which the kernel is impregnated with gaseous hydrocarbons at 800‹ to 1000‹ C. The fuel kernel is next coated with a layer of paste comprising a mixture of graphite and a binding agent and this layer is similarly heat treated with gaseous hydrocarbons at 800‹ to 1000‹ C. Finally, the coated fuel kernel is inserted in a recess formed in a ball of graphite and the recess is closed by a plug bonded in position. In a modification, the fuel kernel has a central core of graphite and the fuel mixture forms a layer around the core. In both constructions, since the mechanical strength of the fuel kernel is greater than that of the graphite ball by a ratio of at least 1.5 to 1, the fuel may be readily separated from the ball after irradiation for reprocessing, by merely applying sufficient crushing force to break the ba.1, the kernel remaining intact. |
