Patent Number: 055531075
Section: claims

1. A pressurized water nuclear reactor pressure vessel, comprising: an upper core support plate having passageways for the passage of coolant;  an upper support plate above the upper core support plate, the upper support plate and the upper core support plate defining a plenum; and  peripheral hollow support columns extending upwardly through the plenum above the passageways in the upper core support plate with each of the peripheral hollow support columns being aligned with a passageway for supporting the upper support plate above the upper core support plate and for guiding coolant from the passageways into the plenum,  each peripheral support column having an unslotted axial lower portion for guiding the coolant flowing through the aligned passageway upwardly through the peripheral support column and having a peripherally slotted upper axial portion for guiding the coolant in the peripheral support column into the plenum. 2. The pressurized water nuclear reactor vessel of claim 1 wherein the vessel has a hot leg nozzle and the peripheral support columns are unslotted below the hot leg nozzle. 3. The pressurized water nuclear reactor vessel of claim 1 wherein the slots in each peripheral support column comprises at least 50% of the peripheral surface area of the upper portion of the support column. 4. The pressurized water nuclear reactor vessel of claim 3 wherein the slots in each peripheral support column comprises from 50% to 66% of the peripheral surface area of the upper portion of the support column. 5. The pressurized water nuclear reactor vessel of claim 1 wherein guide tubes extend from the upper core support plate to the upper support plate, the guide tubes having peripheral slots for guiding coolant into the plenum, and wherein the slotted portion of each peripheral support column is above the slots of the guide tubes.