| 摘要 |
PURPOSE: To avoid the intrusion of steam into a secondary sodium loop toward a reactor vessel when a tube bursting accident happens in the upper section of a steam generator or its vicinity, by providing a concentric auxiliary flow passage from the upper section to a plenum in the lower section of the generator. CONSTITUTION: When, for example, an accident happens at a part 300 in a steam generator M, a diaphragm D in a cylindrical nozzle 270 at the position of a plenum 64 immediately bursts. Then steam flows to the diaphragm D from the reactive part 300 through the spaces between sound tube groups in an area 78, but only part of the gas produced by the large violent reaction is discharged. Another flow passage exists between an inner cylindrical vessel 62 and an intermediate cylindrical vessel 63. When all sodium is discharged, the gas flows upward from the part 300, enters the a coated gas area C' which has become empty, and reaches the top of the intermediate cylindrical vessel 63. Then the gas directly flows to the diaphragm D from the top of the vessel 63 and is discharged. In addition, the steam and supplied water from the part 300 move along a conduit tube 18. Therefore, the accident does not spread to the reactor.
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