| 摘要 |
PURPOSE: To reduce the occurrence of carry-over and carry-under so as to improve the efficiency of an offset chimney having an offset in height by combinedly using the chimney with a drier having an offset in height. CONSTITUTION: A chimney 110 is composed of many divisions and the divisions become taller as going toward the center from the periphery of the chimney 110. Since the central divisions of the chimney 110 are farther from the side wall of a reactor than the peripheral divisions, the steam from the central division takes a long time to get out of the flow of a recirculating flow as compared with the steam from the peripheral divisions. When an offset drier 112 is used, in addition, the flow passage of the steam can be made uniform. Namely, a more preferable carry-over distribution is obtained, because a steam flow passage having an advantageous length to the central divisions is obtained. The taller central divisions of the chimney 110 support taller steam columns, but this generates a large differential pressure, increases the recirculating quantity, drops the bubble fraction at the central part of the core of the reactor, and improves the neutron efficiency.
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