Disclosed is a diagnostic apparatus structured to be electrically connected with a coil stack of a drive mechanism of a control device of a nuclear reactor. The coil stack has a plurality of coils. The diagnostic apparatus includes a power supply and a controller including a processor and a memory that stores a number of routines including a number of instructions. When executed on the processor the instructions cause the diagnostic apparatus to apply to a coil a voltage that varies as a function of time, detect a current in the coil as a function of time, identify in the current a first inflection point and a second inflection point, and determine, based upon an electronic evaluation that includes the first inflection point and the second inflection point, that the coil is one of functioning properly and in a state of at least partial failure.

Disclosed is a diagnostic apparatus structured to be electrically connected with a coil stack of a drive mechanism of a control device of a nuclear reactor. The coil stack has a plurality of coils. The diagnostic apparatus includes a power supply and a controller including a processor and a memory that stores a number of routines including a number of instructions. When executed on the processor the instructions cause the diagnostic apparatus to apply to a coil a voltage that varies as a function of time, detect a current in the coil as a function of time, identify in the current a first inflection point and a second inflection point, and determine, based upon an electronic evaluation that includes the first inflection point and the second inflection point, that the coil is one of functioning properly and in a state of at least partial failure.

A standoff supporting a control rod drive mechanism (CRDM) in a nuclear reactor is connected to a distribution plate which provides electrical power and hydraulics. The standoff has connectors that require no action to effectuate the electrical connection to the distribution plate other than placement of the standoff onto the distribution plate. This facilitates replacement of the CRDM. In addition to the connectors, the standoff has alignment features to ensure the CRDM is connected in the correct orientation. After placement, the standoff may be secured to the distribution plate by bolts or other fasteners. The distribution plate may be a single plate that contains the electrical and hydraulic lines and also is strong enough to provide support to the CRDMs or may comprise a stack of two or more plates.

A standoff supporting a control rod drive mechanism (CRDM) in a nuclear reactor is connected to a distribution plate which provides electrical power and hydraulics. The standoff has connectors that require no action to effectuate the electrical connection to the distribution plate other than placement of the standoff onto the distribution plate. This facilitates replacement of the CRDM. In addition to the connectors, the standoff has alignment features to ensure the CRDM is connected in the correct orientation. After placement, the standoff may be secured to the distribution plate by bolts or other fasteners. The distribution plate may be a single plate that contains the electrical and hydraulic lines and also is strong enough to provide support to the CRDMs or may comprise a stack of two or more plates.

A nuclear reactor (10) includes a vessel (12) containing a primary liquid, a core (14) comprising nuclear fuel and arranged in the internal volume of the vessel (12), at least one primary pump generating a main primary flow (56) of primary liquid in the vessel (12), at least one control member (16) for controlling the reactivity of the core (14), at least one movement mechanism (18) for moving the control member (16), arranged in the internal volume of the vessel (12) and linked to the control member (16), and a pressurizer (20) situated in a top portion of the vessel (12). The movement mechanism (18) comprises an electrical actuator and a transmission mechanism. The electrical actuator is completely immersed in the primary fluid and situated outside the main primary flow (56).

A nuclear reactor (10) includes a vessel (12) containing a primary liquid, a core (14) comprising nuclear fuel and arranged in the internal volume of the vessel (12), at least one primary pump generating a main primary flow (56) of primary liquid in the vessel (12), at least one control member (16) for controlling the reactivity of the core (14), at least one movement mechanism (18) for moving the control member (16), arranged in the internal volume of the vessel (12) and linked to the control member (16), and a pressurizer (20) situated in a top portion of the vessel (12). The movement mechanism (18) comprises an electrical actuator and a transmission mechanism. The electrical actuator is completely immersed in the primary fluid and situated outside the main primary flow (56).

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 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.

Actuator of a nuclear reactor control and protection system comprises: a linear step motor comprising an armature; a rod being coaxial with and connected to the armature to enable joint vertical movement and rotation about a common vertical axis, which rod can form an L-shaped bayonet connection with a working member; and a lock to prevent spontaneous rotation of the rod. The lock comprises a guiding inside the armature and provided with a flange and longitudinal through slot; a cross-member connected to the armature, mounted in the slot and capable of vertical movement therein; a fixed ring, on which the inner surface of the flange rests; and a vertical pin. Through slots are arranged equidistantly in the outside rim of the flange, the vertical pin being mounted in one of several openings arranged equidistantly about the circumference of the fixed ring to pass through one of the through slots.

Actuator of a nuclear reactor control and protection system comprises: a linear step motor comprising an armature; a rod being coaxial with and connected to the armature to enable joint vertical movement and rotation about a common vertical axis, which rod can form an L-shaped bayonet connection with a working member; and a lock to prevent spontaneous rotation of the rod. The lock comprises a guiding inside the armature and provided with a flange and longitudinal through slot; a cross-member connected to the armature, mounted in the slot and capable of vertical movement therein; a fixed ring, on which the inner surface of the flange rests; and a vertical pin. Through slots are arranged equidistantly in the outside rim of the flange, the vertical pin being mounted in one of several openings arranged equidistantly about the circumference of the fixed ring to pass through one of the through slots.