| 摘要 |
PROBLEM TO BE SOLVED: To suppress lowering of reactor pressure during a transition by extending tubing from a drain opening to a reactor liquid surface in a second stage, and constituting a flow passage in which drain does not come directly into contact with a steam dome. SOLUTION: When a transition phenomenon in which a reactor closing a main steam tube and a condensate tube scrams occurs, the steam separator 8 introduces rising gas-liquid two-phase flow into a cylinder after heating, and a swirl flow is given by a wing or the like. Thereby centrifugal force is produced, the liquid phase of large density is collected on the outer peripheral part of a swirl drum 102, separated from steam flowing in the center part in a pick-off ring 103, and drained through the drain passage 104 of the liquid phase and a drain outlet 105. Then, tubing 201 is extended to a reactor liquid surface from the drain outlet 105 in the second stage 102, drainage of subcooled water flowing therein is not directly heat-exchanged with the steam of a steam dome, and a heat transfer area is also markedly reduced. Thus, the lowering width of reactor pressure is also lessened, and pressure lowering is suppressed.
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