Patent ID: 8908822

Claim:
A nuclear reactor comprising: a pressure vessel that includes a coolant inlet nozzle and a coolant outlet nozzle at an upper portion thereof; a core barrel being disposed in the pressure vessel; a core being disposed in the core barrel; a lower plenum being partitioned by the pressure vessel and a bottom portion of the core barrel; and a downcomer portion being partitioned by the pressure vessel and a side wall of the core barrel, and being connected to the coolant inlet nozzle and the lower plenum; a lower core support plate provided at the lower portion of the core barrel; a plurality of columns suspended from the lower core support plate; and a straightener member including an upper straightening ring and a lower straightening ring, the upper straightening ring and the lower straightening ring being connected by the columns to be disposed in the lower plenum, to form two vortex suppressing rings, wherein the lower straightening ring includes a lower outer ring, a lower inner ring, and a plurality of lower spokes disposed radially between the lower outer ring and the lower inner ring, the upper straightening ring includes an upper outer ring, an upper inner ring, and a plurality of upper spokes disposed radially between the upper outer ring and the upper inner ring, and the plurality of columns suspended from the lower core support plate are connected to the upper outer ring and the lower outer ring, and are arranged in the circumferential direction of the upper outer ring and the lower outer ring.