Abstract: A sodium cooled fast ractor comprises a reactor vessel in which a liquid metal coolant is accommodated, a core disposed substantially a lower central portion of the reactor vessel in an installed state, a core support structure secured to the reactor vessel for supporting the core, the core support structure dividing an interior of the reactor vessel into a high-pressure plenum below the core and a low-pressure plenum above the high-pressure plenum, a circulation pump unit for applying a discharge pressure to the liquid metal coolant and circulating the same, and an intermediate heat exchanger for performing a heat exchanging operation of the coolant in the reactor vessel. The circulation pump unit is composed of an electromagnetic circulation pump provided with a discharge port and a closed gas space, which is filled up with a closed gas, defined above and communicated with the discharge port.

Abstract: Stator coils for linear flow electromagnetic induction pumps for pumping liquid metal circulating through a hydraulic system are provided with advantageous deployments of coil power terminals and leads.

Abstract: A tank type nuclear reactor comprises an outer shielding wall structure, a reactor vessel installed in the shielding wall structure and provided with an inner sealed space in which a primary liquid coolant circulates, a reactor core disposed in the reactor vessel and charged with a number of fuel assemblies, a core support structure disposed to a bottom of the reactor vessel, a partition wall structure disposed on the core support structure defining the inner space of the reactor vessel into a hot pool region and a cold pool region, intermediate heat exchangers disposed in the reactor vessel for carrying out heat exchanging operation between the liquid coolant flow from the hot pool region and a secondary side heat medium, and electromagnetic pumps disposed in the reactor vessel for feeding the primary coolant into the core. The partition wall structure has a vertically cylindrical wall structure including a lower portion constituting a core tank portion surrounding an outer periphery of the core.

Abstract: A fuel bundle for a natural-circulation boiling-water reactor includes at least one coolant bypass tube which is at least partially open at both its top and bottom and extends about 2/3 of the bundle height. Water within the bypass tube remains liquid. As it exits the top of the bypass tubes, it merges with and "cools" the flow exterior to the tube. This arrangement reduces the pressure drop across the core, increasing coolant flow. In addition, the merging coolant helps improve heat transfer at the maximum heat flux levels within the core. Lateral holes through the bypass tube can further enhance with heat transfer distribution in the core. The reduced pressure drop in the core and the more uniform heat flux distribution both permit a reactor to operate at higher power ratings.

Abstract: A nuclear reactor coolant pump has a casing defining an inlet nozzle for receiving a reactor coolant fluid, an outlet nozzle for discharging the fluid, and a passage interconnecting the inlet and outlet nozzles through which the fluid can flow in a main stream from the inlet nozzle to outlet nozzle. The pump also has a central rotor with one end disposed adjacent the annular passage of the casing and opposite bearings rotatably mounting the rotor to the casing. A motor is disposed about the rotor and between the bearings and is operable for rotatably driving the central rotor. An impeller is mounted to the one end of the rotor in communication with the annular passage and the flow of fluid therethrough. The impeller rotates with the rotor to create a lower pressure at the inlet nozzle than at the outlet nozzle for drawing the reactor coolant fluid into the casing through the inlet nozzle and discharging the fluid from the casing through the outlet nozzle.

Abstract: A nuclear reactor coolant pump for pumping reactor coolant fluid in a reactor coolant system includes a casing, a rotor and an impeller. The casing defines an inlet nozzle for receiving the fluid, a peripheral outlet nozzle for discharging the fluid, and a passage interconnecting the inlet and outlet nozzles through which the fluid can flow from the inlet to outlet nozzle. The rotor extends axially through the casing and has an end disposed adjacent passage. The impeller is mounted to the end of the rotor and disposed in communication with the passage and offset axially from the outlet nozzle of the casing. The impeller is rotatable with the rotor for drawing fluid into the casing through the inlet nozzle and discharging fluid from the casing tangentially through the peripheral outlet nozzle after flow through the passage. The outlet nozzle is composed of first and second wall portions defined above and below a plane extending generally parallel to the rotation axis of the impeller.

Abstract: A water cooled nuclear reactor comprises a reactor core, a primary water coolant circuit and a pressurizer arranged as an integral unit in a pressure vessel. The pressure vessel is divided into an upper chamber and a lower chamber by a casing, the reactor core and primary coolant circuit are arranged in the lower chamber and the pressuriser is arranged in the upper chamber.A plurality of pipes interconnect a steam space of the pressuriser with an upper portion of the primary coolant circuit via ports in the casing. A plurality of re-entrant surge ports interconnect a water space of the pressuriser with a lower portion of the primary coolant circuit. The surge ports have low flow resistance for water from the water space to the primary coolant circuit and high flow resistance in the opposite direction.

Abstract: A fuel assembly has a water rod which consists of a coolant ascending path and a coolant descending path, the coolant ascending path opening below a fuel support of a lower tie plate, the coolant descending path opening above the fuel support and adapted to guide downwardly the coolant that has flowed up the coolant ascending path to the upper portion of the water rod. The lateral cross section of the coolant ascending path is more than 25 times that of the coolant descending path.The nuclear reactor with these fuel assemblies loaded in the core is operated as follows. After startup of the reactor when the reactor power is low, all the control rods inserted in the core are withdrawn completely. Then, the reactor power is controlled by regulating a liquid level formed in the water rods. This reactor operation method prolongs the lifetime of the control rods, thereby reducing the number of times they have to be replaced.

Abstract: A pressurized water nuclear reactor includes a reactor core, a nuclear reactor fuel assembly disposed in the reactor core, a fuel rod disposed in the fuel assembly, and a nuclear fuel column disposed in the fuel rod being enriched to a variable extent with fissionable nuclei over the length thereof. The reactor core has an inlet for liquid water acting as coolant closest one end of the fuel rod and of the fuel assembly and an outlet for the liquid water closest to the other end of the fuel rod and of the fuel assembly. A steam generator has a primary tube connected to the inlet and the outlet. One half of the nuclear fuel column at the outlet having an average enrichment being less than the average enrichment of the other half of the fuel column, and/or the nuclear fuel column having a depletion zone with an average enrichment being less than the average enrichment over the entire length of the column.

Abstract: A device for suspending a core cover from a sealing slab of a fast neutron nuclear reactor of the type comprising a vertically axed vessel structure filled with liquid metal, closed by the slab and containing the reactor core. The device comprises an upper row and a lower row of superimposed, generally flat, planar, metal plates enabling the rows to be joined to the slab and to the core cover, each row of plates defining a closed convex envelope. The plates are flexible in a direction radial relative to the envelope, while being rigid in a direction circumferential with respect to the envelope. The two rows of flexible plates are interconnected by a lattice of rigid bars in an "X" or "V" form. The upper row plates have upper edges rigidly fixed in position relative to the slab and lower edges rigidly fixed in position relative to the lattice. The lower row plates have upper edges rigidly fixed in position relative to the lattice and lower edges rigidly fixed in position relative to the core cover.

Abstract: Integrated nuclear reactor cooled by a liquid metal and incorporating a main vessel sealed in its upper part by a slab, an inner vessel containing the core, the latter resting on a system for the positioning and supply of the core with liquid metal and which is called the support, the latter itself resting on a supporting structure bearing on the bottom of the main vessel of the reactor, wherein it comprises an inner baffle cladding the side wall and bottom of the main vessel and defining with the latter an intermediate space filled with the liquid metal, tubes for supplying a liquid metal to the intermediate space below the bottom of the main vessel and tubes for returning said liquid metal to an auxiliary exchanger in order to remove heat from the intermediate space.

Abstract: A temperature control system for liquid plant is comprised of liquid metal, plant members, heaters for heating these liquid metal and the plant members at respective control points, a temperature control unit and a control unit. The plant members include a vessel containing liquid metal, pipe lines through which the liquid metal circulates, and valves. Further, temperature sensors, a level detector for detecting the level of the liquid metal, and a meter for detecting the flow rate of the liquid metal, are mounted to the plant members. Temperature sensors produce output signals relating to the condition parameter of the plant which data is delivered via an interface to the temperature control system and the control unit, as the information at each control point. The control unit previously stores the operating schedule of the plant members and transfers, the input signal relating to the plant condition to the temperature control system, with reference to the temperature control schedule.

Abstract: A fuel pin for a liquid metal nuclear reactor is provided. The fuel pin includes a generally cylindrical cladding member with metallic fuel material disposed therein. At least a portion of the fuel material extends radially outwardly to the inner diameter of the cladding member to promote efficient transfer of heat to the reactor coolant system. The fuel material defines at least one void space therein to facilitate swelling of the fuel material during fission.