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.

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 subcritical reactivity monitor that utilizes one or more primarily gamma sensitive (prompt responding) self-powered detector style radiation measurement devices located within the core of a nuclear reactor to determine the amount that the reactor multiplication factor (K.sub.eff) is below the reactivity required to achieve or maintain a self-sustaining nuclear chain reaction. This invention utilizes measured changes in the self-powered detectors' current(s) to allow a reactor operator to measure the value of K.sub.eff at essentially any desired interval while the reactor is shutdown with a K.sub.eff value less than the critical value of 1.0. This invention will enable integration of the output of the value of K.sub.eff directly into the Reactor Protection System, which will enable the elimination of the operational and core design analysis constraint costs associated with the current Boron Dilution Accident prevention methodology and enable automatic control of the Chemical Volume Control System.

A subcritical reactivity monitor that utilizes one or more primarily gamma sensitive (prompt responding) self-powered detector style radiation measurement devices located within the core of a nuclear reactor to determine the amount that the reactor multiplication factor (K.sub.eff) is below the reactivity required to achieve or maintain a self-sustaining nuclear chain reaction. This invention utilizes measured changes in the self-powered detectors' current(s) to allow a reactor operator to measure the value of K.sub.eff at essentially any desired interval while the reactor is shutdown with a K.sub.eff value less than the critical value of 1.0. This invention will enable integration of the output of the value of K.sub.eff directly into the Reactor Protection System, which will enable the elimination of the operational and core design analysis constraint costs associated with the current Boron Dilution Accident prevention methodology and enable automatic control of the Chemical Volume Control System.

A control rod drive mechanism for use in a nuclear reactor including a reactor core disposed in a pressure vessel, including a control rod configured for insertion into the reactor core, a lead screw, the control rod being secured to the bottom end of the lead screw, a drive mechanism including a torque tube having a top end and a bottom end, a pair of segment arms that are pivotably mounted to the torque tube, a pair of roller nuts, each roller nut being rotatably secured to the bottom end of a respective segment arm, and a drive motor including a stator and a rotor secured to the top end of the torque tube that includes a plurality of permanent magnets embedded therein, wherein the stator defines a central bore in which the rotor is disposed, and a latch coil assembly including a latch coil, wherein the latch coil assembly defines a central bore in which the top ends of the segment arms are disposed radially-inwardly of the latch coil.

A rotation apparatus is usable with a control drum in a nuclear environment. The control drum is situated on a shaft that is rotatable about a horizontal axis of rotation, and the control drum includes an absorber portion and a reflector portion. The rotation apparatus includes a rotation mechanism that is structured to apply to the shaft in an operational position a force that biases the shaft to rotate toward a shutdown position, with the force being resisted by a motor to retain the shaft in the operational position when the motor is powered. The force is not resisted when the motor is unpowered. The rotation apparatus further includes a rotation management system that controls the rotation of the shaft.

A rotation apparatus is usable with a control drum in a nuclear environment. The control drum is situated on a shaft that is rotatable about a horizontal axis of rotation, and the control drum includes an absorber portion and a reflector portion. The rotation apparatus includes a rotation mechanism that is structured to apply to the shaft in an operational position a force that biases the shaft to rotate toward a shutdown position, with the force being resisted by a motor to retain the shaft in the operational position when the motor is powered. The force is not resisted when the motor is unpowered. The rotation apparatus further includes a rotation management system that controls the rotation of the shaft.

Control rod drives include linearly-moveable control elements inside an isolation barrier. Control rod drives move the control element through a motor and rotor powering a linear screw internal to an isolation barrier. Induction coils may generate magnetic fields and be moveable across a full stroke length of the control element in the reactor. The magnetic fields hold closed a releasable latch to disconnect the control elements from the linear drives. A control rod assembly may join to the control element. The control rod assembly may lock with magnetic overtravel latches inside the isolation barrier to maintain an overtravel position. Overtravel release coils outside the isolation barrier may release the latches to leave the overtravel position. Operation includes moving the magnetic fields and releasable latch together on opposite sides of an isolation barrier to drive the control element to desired insertion points, including full insertion by gravity following de-energization.

An electro-technical device includes a first coil connected to a first sensor for receiving a current therefrom representative of a sensed condition, the first coil being anchored at first and second ends. A second coil is connected to a second sensor for receiving a current therefrom representative of a sensed condition, the second coil being anchored at first and second ends and being adjacent to the first coil. When the first and second coils receive an increased current from the first and second sensors, the first and second coils each create a magnetic flux that repel one another in order to cause at least one of the coils to break so that a shutdown signal can be sent.

An electro-technical device includes a first coil connected to a first sensor for receiving a current therefrom representative of a sensed condition, the first coil being anchored at first and second ends. A second coil is connected to a second sensor for receiving a current therefrom representative of a sensed condition, the second coil being anchored at first and second ends and being adjacent to the first coil. When the first and second coils receive an increased current from the first and second sensors, the first and second coils each create a magnetic flux that repel one another in order to cause at least one of the coils to break so that a shutdown signal can be sent.