Patent ID: 9230697
Filing Date: 2016-01-05
CPC Classification: F22B,G21C,G21D,Y02E

Claim Text:
1. A nuclear reactor steam generator, comprising: three or four plenums proximate with a first plane; three or four plenums proximate with a second plane; and a plurality of steam-generating tubes that form a coolant flowpath from one of the three or four plenums located proximate with the first plane to at least one of the three or four plenums proximate with the second plane, wherein the steam generator is configured to be installed in a reactor vessel such that the first plane intersects a bottom portion of a riser column positioned in the reactor vessel and the second plane intersects a top portion of the riser column, wherein each of the three or four plenums proximate with the first plane and each of the three or four plenums proximate with the second plane includes an approximately flat tubesheet that faces in a direction of a middle portion of the riser column, and wherein the approximately flat tubesheet includes a plurality of perforations, the perforations being of lower density near an edge closer to the riser column than near an edge closer to a reactor vessel wall.