A control rod drive mechanism having a torque tube, a control rod assembly including a connecting rod and a spider, a lock cam assembly rotatably secured to a bottom end of the connecting rod and including a locking cam, and a locking collar disposed non-rotatably within the spider, the locking collar including a locking recess with an entry slot, wherein in a first axial position the lock cam assembly is rotatable with respect to the torque tube, and a second axial position the lock cam assembly is non-rotatable with respect to the torque tube.

A control rod drive mechanism having a torque tube, a control rod assembly including a connecting rod and a spider, a lock cam assembly rotatably secured to a bottom end of the connecting rod and including a locking cam, and a locking collar disposed non-rotatably within the spider, the locking collar including a locking recess with an entry slot, wherein in a first axial position the lock cam assembly is rotatable with respect to the torque tube, and a second axial position the lock cam assembly is non-rotatable with respect to the torque tube.

A control rod drive mechanism having a torque tube, a control rod assembly including a connecting rod disposed within the torque tube and including an annular collar defining a key slot, an elongated key that is slidably receivable within the key slot, a lock cam assembly rotatably secured to a top end of the connecting rod and including a locking cam, and a holdout collar disposed non-rotatably within the torque tube, the holdout collar including a locking recess with an entry slot, wherein in a first axial position the lock cam assembly is rotatable with respect to the torque tube, and a second axial position the lock cam assembly is non-rotatable with respect to the torque tube.

A control rod drive mechanism having a torque tube, a control rod assembly including a connecting rod disposed within the torque tube and including an annular collar defining a key slot, an elongated key that is slidably receivable within the key slot, a lock cam assembly rotatably secured to a top end of the connecting rod and including a locking cam, and a holdout collar disposed non-rotatably within the torque tube, the holdout collar including a locking recess with an entry slot, wherein in a first axial position the lock cam assembly is rotatable with respect to the torque tube, and a second axial position the lock cam assembly is non-rotatable with respect to the torque tube.

A control rod drive mechanism having a torque tube with an inner surface defining a central bore, a control rod assembly including a connecting rod including a cam extending radially-outwardly therefrom and an annular collar defining a key slot, an elongated key that is slidably receivable within the key slot, and a holdout collar disposed non-rotatably within the torque tube and defining a locking recess, wherein the connecting rod is axially-movable with respect to the torque tube between a first position in which the elongated key is disposed within the key slot so that the connecting rod is non-rotatable with respect to the torque tube, and a second position in which the elongated key is removed from the key slot and the connecting rod is rotatable with respect to the torque tube.

A control rod drive mechanism having a torque tube with an inner surface defining a central bore, a control rod assembly including a connecting rod including a cam extending radially-outwardly therefrom and an annular collar defining a key slot, an elongated key that is slidably receivable within the key slot, and a holdout collar disposed non-rotatably within the torque tube and defining a locking recess, wherein the connecting rod is axially-movable with respect to the torque tube between a first position in which the elongated key is disposed within the key slot so that the connecting rod is non-rotatable with respect to the torque tube, and a second position in which the elongated key is removed from the key slot and the connecting rod is rotatable with respect to the torque tube.

A stationary control rod that controls overall nuclear reactivity and axial reactivity distribution of a fuel assembly, such that power level and axial power distribution within the fuel assembly is controlled without the need for movable control rods and associated hardware. The device uses magnetic fields to control the concentration and distribution of a magneto-rheological fluid containing a material with a very high neutron capture cross section, contained in one or more enclosed thimbles placed within existing thimbles in a fuel assembly. The magnetic fields are generated from electricity produced from interactions of the radiation particles within the core, or supplied using electrical cables that attach to fuel assembly top nozzles. The electricity drives a device that encloses associated wire coil assemblies that surround different axial regions of a tube that contains the magneto-rheological fluid.

A stationary control rod that controls overall nuclear reactivity and axial reactivity distribution of a fuel assembly, such that power level and axial power distribution within the fuel assembly is controlled without the need for movable control rods and associated hardware. The device uses magnetic fields to control the concentration and distribution of a magneto-rheological fluid containing a material with a very high neutron capture cross section, contained in one or more enclosed thimbles placed within existing thimbles in a fuel assembly. The magnetic fields are generated from electricity produced from interactions of the radiation particles within the core, or supplied using electrical cables that attach to fuel assembly top nozzles. The electricity drives a device that encloses associated wire coil assemblies that surround different axial regions of a tube that contains the magneto-rheological fluid.

A control rod assembly having a connecting rod, a spider, a plurality of control rods, a coupling sleeve secured to the connecting rod and including a body portion defining at least one cam pin, and a barrel cam defining a cam track, the barrel cam being rotatably secured to the spider. The cam track includes a first camming surface and a second camming surface that are configured so that the barrel cam rotates in a first direction as the at least one cam pin slides along the first and second camming surfaces. The barrel cam rod is rotatable between a first position in which the spider is connected to the connecting rod and a second position in which the spider is disconnected from the connecting rod.

A control rod assembly having a connecting rod, a spider, a plurality of control rods, a coupling sleeve secured to the connecting rod and including a body portion defining at least one cam pin, and a barrel cam defining a cam track, the barrel cam being rotatably secured to the spider. The cam track includes a first camming surface and a second camming surface that are configured so that the barrel cam rotates in a first direction as the at least one cam pin slides along the first and second camming surfaces. The barrel cam rod is rotatable between a first position in which the spider is connected to the connecting rod and a second position in which the spider is disconnected from the connecting rod.