Abstract: In a nuclear reactor water cleanup pump, a purge fluid is continuously delivered during at least the operation of the pump into the cavities containing the bearings and the electrical motor at a desired flow rate. The desired flow rate being based on the heat loss from said pump and a differential temperature defined as being the difference between the predetermined temperature of the purge fluid delivered into the pump and the desired temperature for the purge fluid exiting the pump.

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.