Integral reactor pressure vessel tube sheet

A reactor pressure vessel tube sheet comprising:

• a horizontally oriented plate that divides a reactor pressure vessel into an upper reactor pressure vessel region located above the plate and a lower reactor pressure vessel region located below the plate, wherein the plate the plate is configured to provide a barrier between a pressurized volume located within the upper reactor pressure vessel region and primary coolant located within the lower reactor pressure vessel region;
• a number of mounting holes located within the plate and configured to receive a plurality of heat transfer tubes that transmit a secondary coolant into the reactor pressure vessel;
• and
• a number of orifices located within the plate and configured to controllably allow the primary coolant to pass from the lower reactor pressure vessel region to the upper reactor pressure vessel region, and configured to pass the primary coolant and the secondary coolant through the plate without becoming comingled with each other.