Abstract: A pump powered by a canned motor has a removable stator cartridge. One end of a generally hollow pressure housing is secured to a pump housing. An annular stator cartridge is removably secured in the pressure housing. An annular gap between the inner surface of the pressure housing and the outer surface of the stator cartridge defines a flow path for cooling fluid to permit the stator cartridge to be surrounded by cooling fluid. A rotor is operatively positioned inside the stator cartridge to form an electric motor when the stator cartridge is energized. The output shaft of the rotor is connected to an impeller in the pump housing. The rotor is rotatably supported by bearings. An end cap is removably secured to the other end of the pressure housing. Removal of the end cap permits access to and removal of the stator cartridge without requiting removal of the motor from the pump housing.

Abstract: A hydraulic lock for latching a displacer rod drive mechanism in an up position. A piston having a truncated cone-shaped valve element is formed at an end of the drive rod. A complementary truncated cone-shaped valve seat is formed in the cap of the reactor housing. When the drive rod is activated to the up position, the valve element seats against the valve seat creating a seal and a pressure boundary. The piston is provided with piston rings. The pressure differential acting across the piston is transferred to the area of contact between the valve element and valve seat thus maintaining the drive rod in the up position and preventing leakage flow from around the piston rings. A hydraulic control system for operating the hydraulic latch is also disclosed.

Abstract: A vent system for controlling hydraulically actuated drive means for selectively moving pluralities of rod clusters respectively connected to the plurality of drive means between fully inserted positions within the lower barrel assembly of the vessel in telescoping relationship with fuel rod assemblies contained therein, and a fully withdrawn position. Each drive means responds to the reactor coolant fluid pressure and includes a leakage passage and an outlet channel through which a leakage flow may pass under control of the vent system, the latter comprising a valve arrangement, flow restrictors and a common orifice through which the outlet channels are selectively connected to essentially ambient pressure, for establishing a pressure differential within each drive means producing a net force for moving the drive rods and associated clusters to the withdrawn position at which the drive means mechanically latch the fully withdrawn clusters for mechanically supporting same in the fully withdrawn position.