Cover gas control systems include a reservoir and injection path for direct injection into fuel transfer machinery. If seals in the fuel handling machinery leak, cover gas is provided from the reservoir to flow to the leak without contamination from a reactor to which the fuel transfer machinery is joined. This providing cover gas may be passive or automatic in response to a detected low pressure level, detected ambient air ingress, low volume level of cover gas, or manually actuated through an operator. The cover gas may be injected from below the leak but above the reactor. A limitation in the injection path keeps cover gas injection at rates sufficient to allow operator reaction and sealing before the reservoir is depleted. A pressure pulse transmitter, blowout preventer, and transfer port plug are useable in the systems, which can be implemented in fuel handling machinery for reactors using a cover gas.

An installation includes: a plurality of pilings securable to a bed under a surface of a body of water; a base structure disposed atop the plurality of pilings; and a module disposable on the base structure, wherein the module is positioned and securable on the base structure after being floated on the surface of the body of water over the base structure.

An entire nuclear fuel core comprising a plurality of fuel assemblies is preassembled in a nuclear fuel cartridge having a self-supporting unitary support structure. During a refueling operation, the unitary support structure is moved into a nuclear reactor vessel. The unitary support structure may be formed by top and bottom core plates coupled together by vertically-oriented connecting rods which compress the fuel assemblies therebetween. A plurality of reflector wall segments circumscribe the core and are the coupled together between the core plates by the connecting rods which are coupled to the core plates. The connecting rods may extend through the wall segments.

An entire nuclear fuel core comprising a plurality of fuel assemblies is preassembled in a nuclear fuel cartridge having a self-supporting unitary support structure. During a refueling operation, the unitary support structure is moved into a nuclear reactor vessel. The unitary support structure may be formed by top and bottom core plates coupled together by vertically-oriented connecting rods which compress the fuel assemblies therebetween. A plurality of reflector wall segments circumscribe the core and are the coupled together between the core plates by the connecting rods which are coupled to the core plates. The connecting rods may extend through the wall segments.

Portable nuclear fuel cartridge comprising a unitary support structure and plurality of nuclear fuel assemblies that collectively form a nuclear fuel core. Control rod drive system for a nuclear reactor. A nuclear steam supply system having a shutdown system for removing residual decay heat generated by a nuclear fuel core. A nuclear reactor including a cylindrical body having an internal cavity, nuclear fuel core, and a shroud disposed in the cavity. A nuclear reactor cooling system with passive cooling capabilities operable during a loss-of-coolant accident (LOCA) without available electric power.

An assembly to be inserted into a nuclear reactor, such as a liquid sodium-cooled fast neutron reactor, includes an assembly hollow body of elongate shape along a longitudinal axis X. The wall of the hollow body includes at least one through-opening. The assembly also includes an assembly element inserted into the hollow body. The assembly element includes at least one flexible blade of which the free end is shaped into a clip-fastening hook collaborating in clip-fastening fashion with the through-opening from inside the hollow body, so as to connect the assembly element to the hollow body. The assembly also includes at least one removable structure for locking the flexible blade clip-fastened into the through-opening. The removable locking structure makes it possible to prevent the flexible blade from flexing and thus the removable locking structure makes it possible to lock a connection between the assembly element and the hollow body.

An assembly to be inserted into a nuclear reactor, such as a liquid sodium-cooled fast neutron reactor, includes an assembly hollow body of elongate shape along a longitudinal axis X. The wall of the hollow body includes at least one through-opening. The assembly also includes an assembly element inserted into the hollow body. The assembly element includes at least one flexible blade of which the free end is shaped into a clip-fastening hook collaborating in clip-fastening fashion with the through-opening from inside the hollow body, so as to connect the assembly element to the hollow body. The assembly also includes at least one removable structure for locking the flexible blade clip-fastened into the through-opening. The removable locking structure makes it possible to prevent the flexible blade from flexing and thus the removable locking structure makes it possible to lock a connection between the assembly element and the hollow body.

Chimneys include several combinable parts useable in nuclear reactors. The parts are modular and removably joinable without destruction for use in directing flow in an operating nuclear reactor and directly fit in storage area during non-operation. Chimney parts are joinable through flanges and connecting structures. Chimney parts may include partitions that divide or direct energetic coolant flow from a nuclear core as well as steam separating and drying structures. The parts each individually fit within storage areas of the nuclear plant, including equipment or buffer pools in the refueling floor of the plant. Methods move the chimney parts between the reactor and storage areas, and multiple parts may be stacked or nested in such moves. Methods are useable underwater and with storage pools to prevent exposure of chimney parts during an outage. During operation, chimneys are useable in place of existing single-piece chimneys.

A nuclear reactor can include a pressure vessel for containing a pressurized moderator at a first pressure. The nuclear reactor can also include a plurality of fuel channels for a coolant fluid at a second pressure. The plurality of fuel channels are fluidly connected at inlet ends thereof to a coolant supply conduit and are adapted to receive nuclear fuel bundles and to be mounted within the pressure vessel and surrounded by the moderator. The outlet ends of the fuel channels are fluidly connected to a coolant outlet conduit to enable the coolant fluid to circulate from the coolant supply conduit through the fuel channels to the coolant outlet conduit. The plurality of fuel channels maintain separation between the coolant fluid circulating within the fuel channels and the moderator.

A nuclear reactor can include a pressure vessel for containing a pressurized moderator at a first pressure. The nuclear reactor can also include a plurality of fuel channels for a coolant fluid at a second pressure. The plurality of fuel channels are fluidly connected at inlet ends thereof to a coolant supply conduit and are adapted to receive nuclear fuel bundles and to be mounted within the pressure vessel and surrounded by the moderator. The outlet ends of the fuel channels are fluidly connected to a coolant outlet conduit to enable the coolant fluid to circulate from the coolant supply conduit through the fuel channels to the coolant outlet conduit. The plurality of fuel channels maintain separation between the coolant fluid circulating within the fuel channels and the moderator.