Patent Number: 
Section: claims

1. A modular pressurized water reactor having a primary circuit including a reactive core, an upper internals, a steam generator heat exchanger and pressurizer housed within a reactor pressure vessel which is enclosed within a substantially close fitting containment, including a primary coolant hot leg between a coolant flow exit from the core and an upstream side of the steam generator heat exchanger and a coolant cold leg between a downstream side of the steam generator heat exchanger and a coolant flow entrance to the core, the hot leg and cold leg being housed within the reactor pressure vessel, the modular pressurized water reactor further including a combined passive heat removal system and high-head water injection system comprising:a core makeup tank including:a heat exchange assembly supported within the core makeup tank, the heat exchange assembly having a primary side and a secondary side, the primary side having an interior flow path within the heat exchange assembly with a primary side inlet and a primary side outlet, the interior flow path being maintained at a pressure at least equal to a pressure within the reactive core;a primary side inlet plenum that is in fluid communication with the inlet of the interior flow path of the heat exchange assembly and the hot leg exiting the core;a primary side outlet plenum that is in fluid communication with the outlet of the interior flow path of the heat exchange assembly and the cold leg between the downstream side of the steam generator heat exchanger and the coolant flow entrance to the core; anda secondary side plenum within the secondary side of the heat exchange assembly having an inlet end and an outlet end and a secondary side flow path over an exterior of the heat exchange assembly interior flow path, connecting the inlet end to the outlet end of the secondary side plenum;an ultimate heat sink heat exchanger is connected to the core makeup tank between the inlet end and the outlet end of the secondary side plenum, wherein the secondary side plenum and a connection with the ultimate heat sink heat exchanger is pressurized to an extent to prevent boiling under accident conditions; andmeans for isolating the primary side of the heat exchange assembly from the core. 2. The modular reactor of claim 1 wherein the core makeup tank is positioned at an elevation above an elevation of the core. 3. The modular reactor of claim 2 wherein the ultimate heat sink heat exchanger is at an elevation above the elevation of the core makeup tank. 4. The modular reactor of claim 1 wherein the core makeup tank is supported outside of the reactor pressure vessel. 5. The modular reactor of claim 4 wherein the core makeup tank is enclosed within the containment. 6. The modular reactor of claim 5 wherein the ultimate heat sink is positioned outside of the containment. 7. The modular reactor of claim 1 wherein the primary side of the heat exchange assembly is pressurized to at least the same pressure as the core. 8. The modular reactor of claim 7 wherein the primary side of the heat exchange assembly is pressurized to substantially the same pressure as the core. 9. The modular reactor of claim 1 wherein the heat exchange assembly is a tube and shell heat exchanger. 10. The modular reactor of claim 9 wherein the primary side inlet plenum is at a top of the core makeup tank and the primary side outlet plenum is at a bottom of the core makeup tank. 11. The modular reactor of claim 1 wherein the means for isolating the primary side of the heat exchange assembly from the core is a valve in fluid communication with the primary side outlet between the primary side outlet plenum and the cold leg. 12. The modular reactor of claim 1 wherein the ultimate heat sink heat exchanger includes a primary side connected to the secondary side of the core makeup tank heat exchange assembly and a secondary side in heat exchange relationship with a pool of coolant. 13. The modular reactor of claim 1 including a plurality of core makeup tanks. 14. The modular reactor of claim 12 wherein the ultimate heat sink is outside the containment and the pool of coolant is substantially at atmospheric pressure of the surrounding environment.