Patent Number: 051184664
Section: abstract

A nuclear reactor coolant pump has a casing defining an inlet nozzle for receiving a reactor coolant fluid, an outlet nozzle for discharging the fluid, and a passage interconnecting the inlet and outlet nozzles through which the fluid can flow in a main stream from the inlet nozzle to outlet nozzle. The pump also has a central rotor with one end disposed adjacent the annular passage of the casing and opposite bearings rotatably mounting the rotor to the casing. A motor is disposed about the rotor and between the bearings and is operable for rotatably driving the central rotor. An impeller is mounted to the one end of the rotor in communication with the annular passage and the flow of fluid therethrough. The impeller rotates with the rotor to create a lower pressure at the inlet nozzle than at the outlet nozzle for drawing the reactor coolant fluid into the casing through the inlet nozzle and discharging the fluid from the casing through the outlet nozzle. A self-cooling arrangement provided in the pump defines a fluid flow loop in communication with the annular passage and in heat transfer relationship with the bearings and motor. The self-cooling arrangement is operable for diverting only a fraction of the fluid from and back to the main stream through the annular passage to cool the bearings and motor. Foreign particle deflectors are provided to minimize passage of particles into the fluid flow loop.