Systems join with a control rod drive and expand or contract to displace elements necessary for decoupling. Joining structures affix to on sides of the control rod drive allow discriminatory jacking by a powered drive also in contact with the control rod drive. A moveable piston tube can be displaced by this jacking with hundreds or thousands of pounds of force with respect to the control rod drive. Probes and other instrumentation and sensors are useable in the systems to accurately measure any of piston tube displacement, temperature, malfunction; drive power status, displacement or speed; and communications status. Manual interaction with the systems are not required during the jacking, and installation and removal of the systems requires no tools or great amount of time or effort. Through remote operation and brief installation, human exposure to radiation about control rod drives is minimized.

Systems join with a control rod drive and expand or contract to displace elements necessary for decoupling. Joining structures affix to on sides of the control rod drive allow discriminatory jacking by a powered drive also in contact with the control rod drive. A moveable piston tube can be displaced by this jacking with hundreds or thousands of pounds of force with respect to the control rod drive. Probes and other instrumentation and sensors are useable in the systems to accurately measure any of piston tube displacement, temperature, malfunction; drive power status, displacement or speed; and communications status. Manual interaction with the systems are not required during the jacking, and installation and removal of the systems requires no tools or great amount of time or effort. Through remote operation and brief installation, human exposure to radiation about control rod drives is minimized.

Disclosed is an apparatus, system, and method for monitoring a position of a control rod disposed in a nuclear reactor vessel in a radioactive environment. A data processing unit located outside a containment structure includes a processor and a memory storing executable instructions. A nuclear reactor vessel includes a plurality of control rods proximate to the control rod and a coil stack of a plurality of control rod position indicator coils. A data cabinet mounted on the nuclear reactor vessel head inside the containment structure includes an analog multiplexer and a communication circuit. The processor executes the instructions to select a control rod position indicator coil through the analog multiplexer, pass a signal from the control rod position indicator coil through the analog multiplexer, receive the signal from the analog multiplexer through the communication circuit, and determine a position of the control rod based on the received signal.

Arrangements and devices for reducing and/or preventing wear of a thermal sleeve in a nuclear reactor are disclosed. Arrangements include a first structure provided on or in one the thermal sleeve and a second structure provided on or in the head penetration adapter. At least a portion of the first structure and at least another portion of the second structure interact to resist, reduce, and/or prevent rotation of the thermal sleeve about its central axis relative to the head penetration adapter. Devices include a base for coupling to a guide tube of the reactor and a plurality of protruding members extending upward from the base. Each member having a portion for engaging a corresponding portion of a guide funnel of the thermal sleeve.

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.

A nuclear reactor is provided. The reactor includes a reactor pressure vessel housing plural fuel rods containing fissile material, the reactor pressure vessel having an upper, removable, vessel head. The reactor further includes control rods, each made of a neutron-absorbing material. The control rods are inserted into the reactor through the vessel head and between the fuel rods to control the rate of the fuel rods' fission reaction. The control rods are movable over a normal range of insertion positions relative to the vessel head to control the power output of the reactor when it is critical and generating useful power, and to put the reactor in a sub-critical shutdown state. The reactor further includes control rod drive mechanisms carried by the vessel head and operable to drive the movements of the control rods. The control rod drive mechanisms are controllable to release the control rods when a vessel opening operation is performed in which the reactor is in the shutdown state and the vessel head is lifted upwards from the reactor pressure vessel such that the control rods slide therethrough to remain stationary relative to the fuel rods to maintain the shutdown state. The reactor further has monitoring unit to identify whether a control rod is accidently lifting with the vessel head.

A compact nuclear reactor system can include a set of nuclear reactor each including: a moderating body; a heat pipe disposed within the moderating body and arranged substantially parallel to the longitudinal axis; nuclear fuel arranged within the moderating body and configured to heat a working fluid passable through the heat pipe; and a neutron moderator arranged within the moderating body and configured to slow a rate of fission within the moderating body. The compact nuclear reactor system can also include a control system including: a rotatable sleeve defining a first portion including a neutron poison material; and a second portion including a neutron transparent material. The compact nuclear reactor system can also include a drive system connected to the sleeve and configured to rotate the sleeve about the sleeve axis to control neutron flux between the set of nuclear reactor cores.

A compact nuclear reactor system can include a set of nuclear reactor each including: a moderating body; a heat pipe disposed within the moderating body and arranged substantially parallel to the longitudinal axis; nuclear fuel arranged within the moderating body and configured to heat a working fluid passable through the heat pipe; and a neutron moderator arranged within the moderating body and configured to slow a rate of fission within the moderating body. The compact nuclear reactor system can also include a control system including: a rotatable sleeve defining a first portion including a neutron poison material; and a second portion including a neutron transparent material. The compact nuclear reactor system can also include a drive system connected to the sleeve and configured to rotate the sleeve about the sleeve axis to control neutron flux between the set of nuclear reactor cores.

Detachable connection of a linear motor tubular armature and a vertical cylindrical rod of a nuclear reactor actuator, the rod, located in a guide pipe, is installed in the armature with an annular gap, in which a tubular fork with pins is placed. L-shaped slots are made at the end of the armature, vertical slots are made above them and the lower part of the armature is closed with a longitudinally fixed plug. On the side surface of the plug, -shaped grooves are made for the insertion or removal of the fork pins. Also, radial protrusions are made on the rod, and in the guide pipe, below the vertical slots of the armature, a bushing with -shaped grooves is fixed coaxially to the armature with the possibility of inserting the protrusions of the rod into, or removing the protrusions of the rod from, the grooves.