A motor-driven centrifugal pump for circulating a coolant in a primary circuit of a nuclear reactor comprises a sealed motor unit, a hydraulic part and a shaft which is immersed in the coolant, turned by the sealed motor unit and pumping the coolant by means of an impeller of the hydraulic part secured to the shaft; the motor unit comprising a dry stator and an immersed rotor mounted securely on the shaft. The motor-driven pump also comprises an immersed flywheel mounted securely on the shaft between the rotor of the motor unit and the impeller of the hydraulic part, allowing a minimum slowing-down time after the electrical power supply is cut; the flywheel comprising a vaned wheel generating a circulation of the coolant to cool the motor unit.

A canned rotodynamic flow machine (1) configured for operating with a working fluid such as molten salt of a molten salt nuclear reactor. The stator windings are formed by one or more electrically conductive solid bars (12).

A thermal actuator for a rotating shaft shutdown seal that has a piston with a portion of its axial length enclosed within a chamber shell with a material that expands upon a rise in temperature. The portion of the actual length of the piston within the chamber has at least two different diameters with the larger diameter leading in the direction of travel of the piston. Upon a rise in temperature, expansion of the material surrounding the piston within the chamber creates a force on the piston in the desired direction of travel. Below a preselected temperature the piston is positively locked with a passive release when the preselected temperature is reached.

A thermal actuator for a rotating shaft shutdown seal that has a piston with a portion of its axial length enclosed within a chamber shell with a material that expands upon a rise in temperature. The portion of the actual length of the piston within the chamber has at least two different diameters with the larger diameter leading in the direction of travel of the piston. Upon a rise in temperature, expansion of the material surrounding the piston within the chamber creates a force on the piston in the desired direction of travel. Below a preselected temperature the piston is positively locked with a passive release when the preselected temperature is reached.

A pressurized water reactor (PWR) includes a vertical cylindrical pressure vessel having a lower portion containing a nuclear reactor core and a vessel head defining an internal pressurizer. A reactor coolant pump (RCP) mounted on the vessel head includes an impeller inside the pressure vessel, a pump motor outside the pressure vessel, and a vertical drive shaft connecting the motor and impeller. The drive shaft does not pass through the internal pressurizer. A central riser may be disposed concentrically inside the pressure vessel, and the RCP impels primary coolant downward into a downcomer annulus between the central riser and the pressure vessel. A steam generator may be disposed in the downcomer annulus and spaced apart from with the impeller by an outlet plenum. A manway may access the outlet plenum so tube plugging can be performed on the steam generator via access through the manway without removing the RCP.

A pressurized water reactor (PWR) includes a vertical cylindrical pressure vessel having a lower portion containing a nuclear reactor core and a vessel head defining an internal pressurizer. A reactor coolant pump (RCP) mounted on the vessel head includes an impeller inside the pressure vessel, a pump motor outside the pressure vessel, and a vertical drive shaft connecting the motor and impeller. The drive shaft does not pass through the internal pressurizer. A central riser may be disposed concentrically inside the pressure vessel, and the RCP impels primary coolant downward into a downcomer annulus between the central riser and the pressure vessel. A steam generator may be disposed in the downcomer annulus and spaced apart from with the impeller by an outlet plenum. A manway may access the outlet plenum so tube plugging can be performed on the steam generator via access through the manway without removing the RCP.

The invention relates to a device for sealing a pump of a nuclear power station. Said includes: a mechanical packing and a fluid header. The header includes: a first plurality of surfaces that cooperate with said mechanical packing; a second plurality of surfaces that are designed to cooperate with a pump housing; and a plurality of ducts. The plurality of ducts form, in an operating state, a first fluid circuit that constitutes a thermal barrier between the first plurality of surfaces and the second plurality of surfaces, and a second fluid circuit that supplies fluid to said mechanical packing in order to cool it.

The invention relates to a device for sealing a pump of a nuclear power station. Said includes: a mechanical packing and a fluid header. The header includes: a first plurality of surfaces that cooperate with said mechanical packing; a second plurality of surfaces that are designed to cooperate with a pump housing; and a plurality of ducts. The plurality of ducts form, in an operating state, a first fluid circuit that constitutes a thermal barrier between the first plurality of surfaces and the second plurality of surfaces, and a second fluid circuit that supplies fluid to said mechanical packing in order to cool it.

A method for carrying out emergent shaft sealing for a reactor coolant pump and a shaft sealing assembly is provided. The method comprises the steps that a passive stopping sealing member is arranged in a first sealing assembly and forms an opening under the normal operation condition, without affecting the first sealing assembly using a liquid film formed by fluid static pressure to prevent reactor coolant from leaking along a pump shaft; under the station blackout condition, after sensing high-temperature fluid flowing into the first sealing assembly, the passive stopping sealing member is closed and holds the pump shaft of the reactor coolant pump tightly, the gap between the first sealing assembly and the pump shaft of the reactor coolant pump is blocked, and therefore the reactor coolant is prevented from leaking along the pump shaft.

A method for carrying out emergent shaft sealing for a reactor coolant pump and a shaft sealing assembly is provided. The method comprises the steps that a passive stopping sealing member is arranged in a first sealing assembly and forms an opening under the normal operation condition, without affecting the first sealing assembly using a liquid film formed by fluid static pressure to prevent reactor coolant from leaking along a pump shaft; under the station blackout condition, after sensing high-temperature fluid flowing into the first sealing assembly, the passive stopping sealing member is closed and holds the pump shaft of the reactor coolant pump tightly, the gap between the first sealing assembly and the pump shaft of the reactor coolant pump is blocked, and therefore the reactor coolant is prevented from leaking along the pump shaft.