Abstract: A representative cooling system for a nuclear reactor control rod drive mechanism (CRDM) includes an evaporation section located within or next to the CRDM and a condensation section fluidly coupled to the evaporation section. The cooling system includes a set of heat fins coupled to drive coils in the CRDM and heat pipes that extend through the drive coils and heat fins. A fluid evaporates while in the evaporation section of the heat pipes from heat generated by the CRDM and moves out of the evaporation section into the condensation section in the heat fins. The fluid cools and condensates while in the condensation section, recirculating back into the evaporation section. This passive natural circulation cooling system reduces or eliminates the number of water hoses, piping, and other water pumping equipment typically used for cooling a CRDM thereby increasing nuclear reactor reliability and simplifying nuclear reactor operation and maintenance.

Abstract: The drive assembly includes annular drive magnets extending around a top end of a drive shaft and annular drive coils extending around the drive magnets, separated by a pressure boundary. A latch assembly is coupled to the drive magnets and engages with the drive shaft in response to actuation of the drive assembly. The drive coils also rotate the drive magnets and the engaged latch assembly to axially displace the drive shaft. Deactivating the drive coils disengages the latch assembly from the drive shaft, dropping a connected control rod assembly via gravity into a nuclear fuel assembly.

Abstract: A cooling system for a nuclear reactor control rod drive mechanism (CRDM) includes an evaporation section located within or next to the CRDM and a condensation section fluidly coupled to the evaporation section. The cooling system may include a set of heat fins that extend up from drive coils in the CRDM and heat pipes that extend through the drive coils and heat fins. A fluid evaporates while in the evaporation section of the heat pipes from heat generated by the CRDM and moves out of the evaporation section into the condensation section in the heat fins. The fluid cools and condensates while in the condensation section, recirculating back into the evaporation section. This passive natural circulation cooling system reduces or eliminates the number of water hoses, piping, and other water pumping equipment typically used for cooling CRDM, or the requirement for air cooling, increasing nuclear reactor reliability and simplifying nuclear reactor operation and maintenance.

Abstract: The drive assembly includes annular drive magnets extending around a top end of a drive shaft and annular drive coils extending around the drive magnets, separated by a pressure boundary. A latch assembly is coupled to the drive magnets and engages with the drive shaft in response to actuation of the drive assembly. The drive coils also rotate the drive magnets and the engaged latch assembly to axially displace the drive shaft. Deactivating the drive coils disengages the latch assembly from the drive shaft, dropping a connected control rod assembly via gravity into a nuclear fuel assembly. A disconnect assembly includes a disconnect magnet coupled to the top end of a disconnect rod that extends through the drive shaft. Annular disconnect coils extend around the disconnect magnet, separated by a pressure boundary, to hold the disconnect magnet and the disconnect rod in a raised position to remotely disconnect from, or reconnect the drive shaft to, the control rod assembly.

Abstract: A heat transfer system includes a plenum configured to provide a secondary side fluid such as feedwater to a plurality of heat transfer tubes from a primary side fluid, and a tube sheet coupled to the plurality of heat transfer tubes. An orifice plate is mounted within the plenum and located adjacent to the tube sheet, and one or more orifice devices are supported by the orifice plate and are configured for insertion into or sealing against the plurality of heat transfer tubes. The one or more orifice devices may include center flow orifices, and/or rectangular or helical shaped transition stepped annular flow orifices, and an insertion of a number of the transition steps into the plurality of heat transfer tubes may determine a corresponding pressure drop of the secondary side fluid in the heat transfer system.

Abstract: A heat transfer system includes a plenum configured to provide a secondary side fluid such as feedwater to a plurality of heat transfer tubes from a primary side fluid, and a tube sheet coupled to the plurality of heat transfer tubes. An orifice plate is mounted within the plenum and located adjacent to the tube sheet, and one or more orifice devices are supported by the orifice plate and are configured for insertion into or sealing against the plurality of heat transfer tubes. The one or more orifice devices may include center flow orifices, and/or rectangular or helical shaped transition stepped annular flow orifices, and an insertion of a number of the transition steps into the plurality of heat transfer tubes may determine a corresponding pressure drop of the secondary side fluid in the heat transfer system.