Abstract: A reactor unit cell is disclosed including a graphite moderator structure, a heat pipe positioned in the graphite moderator structure, and a fuel assembly positioned in the graphite moderator structure. The fuel assembly comprises at least one fuel rod. Each fuel rod comprises a beryllium-oxide sleeve and nuclear fuel positioned in the beryllium-oxide sleeve.

Abstract: A nuclear reactor includes a vessel having an outer wall and vessel bottom, and an enclosure delimited by a cylindrical inner wall disposed inside the vessel such that the inner wall and outer wall define a circuit with an annular cross-section. A support element is located adjacent the bottom of the enclosure to hold control elements of the core. A flow diffusion element is positioned between the support element and the vessel bottom and has a circular flat surface portion including disc shaped orifices of the same diameter. The space between the flat portion and the vessel bottom forms an unobstructed mixing zone to allow uniform distribution of flow rates of fluid circulated through the enclosure.

Abstract: Disclosed embodiments include nuclear fission reactor cores, nuclear fission reactors, methods of operating a nuclear fission reactor, and methods of managing excess reactivity in a nuclear fission reactor.

Abstract: A method of loading fuel in multiple reactor cores associated with a plurality of fuel cycles. The method includes, in a first fuel cycle, loading a first reactor core with a first fuel assembly selected from a first batch of fuel, loading the first reactor core with a first partially spent fuel assembly from a second batch of fuel, loading a second reactor core with a second fuel assembly from the first batch of fuel, and loading the second reactor core with a second partially spent fuel assembly from the second batch of fuel. In a second fuel cycle, which is performed after a completion of the first fuel cycle, the method includes loading the second reactor core with a fresh fuel assembly, and loading the second reactor core with the first fuel assembly from the first batch of fuel.

Abstract: There is provided a core of a boiling water reactor that can be operated without loading a new fuel assembly at an operation cycle before decommissioning. The core of the boiling water reactor includes multiple fuel assemblies loaded in a square lattice shape. The multiple fuel assemblies are arranged in the core based on the number of residence cycles of fuel assemblies laterally adjacent and longitudinally adjacent to a fuel assembly having the shortest loading period in core cross section. The arrangement of fuel assemblies is also based on the number of residence cycles of fuel assemblies diagonally adjacent to the fuel assembly having the shortest loading period.

Abstract: A reactor pressure vessel assembly may include a housing surrounding a reactor core, steam separators, and a chimney. Inner surfaces of the chimney and reactor core define a conduit for transporting a two phase flow stream from the reactor core through the chimney to the steam separators. The housing defines an opening. An inner surface of the housing and outer surfaces of the chimney and reactor core define an annulus in fluid communication with the opening and conduit. A feedwater sparger in the housing is connected to the at least one opening and configured to deliver a sub-cooled feedwater into the annulus. A flow barrier structure between the chimney and the steam separators may force mixing between the sub-cooled feedwater and a downcomer fluid from the steam separators. An outer steam separator may be vertically over a portion of the flow barrier structure in a plan view.

Abstract: Illustrative embodiments provide methods and systems for migrating fuel assemblies in a nuclear fission reactor, methods of operating a nuclear fission traveling wave reactor, methods of controlling a nuclear fission traveling wave reactor, systems for controlling a nuclear fission traveling wave reactor, computer software program products for controlling a nuclear fission traveling wave reactor, and nuclear fission traveling wave reactors with systems for migrating fuel assemblies.

Abstract: An advanced initial core fuel configuration is for improving the fuel management efficiency and thus economics for a nuclear reactor. The advanced initial core fuel configuration includes a plurality of fuel assemblies having different average enrichments of uranium 235 and arranging the fuel assemblies in an initial core configuration structured to emulate a known equilibrium reload cycle core at least in terms of spatial reactivity distribution. The resulting average enrichment within the initial core ranges from below about 1.0 percent weight of uranium 235 to about 5.0 percent weight of uranium 235. An advanced lattice design is also disclosed.

Abstract: Illustrative embodiments provide methods and systems for migrating fuel assemblies in a nuclear fission reactor, methods of operating a nuclear fission traveling wave reactor, methods of controlling a nuclear fission traveling wave reactor, systems for controlling a nuclear fission traveling wave reactor, computer software program products for controlling a nuclear fission traveling wave reactor, and nuclear fission traveling wave reactors with systems for migrating fuel assemblies.

Abstract: Disclosed embodiments include nuclear fission reactor cores, nuclear fission reactors, methods of operating a nuclear fission reactor, and methods of managing excess reactivity in a nuclear fission reactor.

Abstract: Disclosed embodiments include nuclear fission reactor cores, nuclear fission reactors, methods of operating a nuclear fission reactor, and methods of managing excess reactivity in a nuclear fission reactor.

Abstract: An advanced initial core fuel configuration is for improving the fuel management efficiency and thus economics for a nuclear reactor. A method of implementing such an initial core involves providing a plurality of fuel assemblies having different average enrichments of uranium 235 and arranging the fuel assemblies in an initial core configuration structured to emulate a known equilibrium reload cycle core at least in terms of spatial reactivity distribution. The resulting average enrichment within the initial core ranges from below about 1.0 percent weight of uranium 235 to about 5.0 percent weight of uranium 235. An advanced lattice design is also disclosed.

Abstract: Fuel assemblies include an outer channel having a physical configuration optimized for a position of the fuel assembly within a core of a nuclear reactor. The position of the fuel assembly with respect to an employed control blade in the nuclear reactor determines if the outer channel may be thickened, reinforced, and/or fabricated of Zircaloy-4 or similar distortion-resistant material, so as to reduce or prevent distortion of the channel against the control blade, or thinned so as to increase water volume and enhance reactivity in the assembly. Reactor cores having configured fuel assemblies include fuel assemblies having different outer channels. Methods include determining operational characteristics of the fuel assembly, including likelihood of being placed directly adjacent to an employed control blade, and physically selecting or modifying the outer channel of the fuel assembly based thereon.

Abstract: The invention provides an automatic mapping method for a distribution network based on logical layout. The method includes: (1) pretreating a model of the distribution network model by analyzing it, and partitioning and striping the distribution network model to generate a plurality of partial models; (2) analyzing an automatic mapping algorithm to be utilized by comparing a distribution network graph obtained by the algorithm with the distribution network model; (3) achieving automatic layout of the partial models or the whole distribution network model on the basis of analysis of the automatic mapping algorithm to be utilized; and (4) analyzing and treating the automatic layout to achieve the generation of the distribution network graph with a desired practical effect.

Abstract: A method for joint configuration of nuclear power plant fuel includes the following steps: (S1) for at least one operating unit, based on an equilibrium cycle or transition cycle reactor core design, at least one new fuel element is added to at least one operating unit; (S2) after running a combustion cycle, and on basis of the new fuel elements in step (S1), more first spent fuel elements are obtained from the at least one operating unit than are obtained from the equilibrium cycle or transition cycle reactor core design, and said first spent fuel elements are kept in reserve; (S3) for at least one new starting unit, a scheduled number of new fuel elements, as well as the first spent fuel elements obtained for reserve in step (S2), are set in the first reactor cores of at least one new starting unit.

Abstract: A system for transferring fuel elements between an upper pool and a lower pool of a nuclear plant has a conveyor tube having an upper end at the upper pool and a lower end at the lower pool. A transport basket movable internally along the tube and into which at least one of the fuel elements can be placed can travel through the conveyor tube. A blocking element at one end of the tube that can fully close the conveyor tube at the respective end. A cable hoist has a traction cable guided through the conveyor tube for raising and lowering the transport basket through the conveyor tube. An intermediate partially closing blocking element offset from the fully closing blocking element in the tube is formed with a cable passage through which the traction cable can pass in the closed position.

Abstract: Fuel elements are moved between an upper pool and a lower pool of a nuclear plant by a conveyor tube having an upper end at the upper pool and a lower end at the lower pool and extending at an acute angle to the vertical between the ends. A plurality of transport baskets can move through the conveyor tube, each holding at least one of the fuel. An upper transfer device at the upper end in the upper pool loads the fuel elements into or unloads them from the transport baskets. A lower transfer device in the lower pool loads fuel elements into or unloads them from the transport baskets. Each transfer device can hold two of the transport baskets that are displaceable for positioning above or below the conveyor tube and movable during displacement through the tube between a vertical transfer position and an angled transport position.

Abstract: A system for transfer of fuel elements between an upper pool and a lower pool of a nuclear plant has a conveyor tube having an upper end in the upper pool and a lower end in the lower pool, formed below the upper end with a laterally open port, and extending between the ends at an acute angle to the vertical. A transport basket into which the fuel elements can be placed can be moved through the conveyor tube by a cable hoist having a cable winch outside the tube and a traction cable guided through the conveyor tube and out of the port and extending along and inside the tube. An upper blocking element can close the upper end of the conveyor tube. The cable port is preferably formed by a lateral hole in the conveyor tube preferably provided directly below the upper blocking element.

Abstract: Enhanced reception in a communication system is achieved by applying a time domain generated time-reversed channel response to signals transmitted from a group of transmitter to a group of receivers. The time-reversed channel response is generated from a radio frequency channel response derived from signals previously received from the group of receivers, but reversed in the time domain. The time-reversed channel response is convolved with an information signal that when transmitted in a coordinated fashion from the group of transmitters, the signals arrive at each receiver in the group of distant receiving communication devices at approximately the same time where the signals coherently combine, thereby increasing signal power at the receivers. This permits detection at a greater range or with a lower bit error rate. In addition, the many-to-many configuration enables signal power from each transmitter to be focused temporarily and spatially on each receiver.

Abstract: Nuclear reactor systems and methods are described having many unique features tailored to address the special conditions and needs of emerging markets. The fast neutron spectrum nuclear reactor system may include a reactor having a reactor tank. A reactor core may be located within the reactor tank. The reactor core may include a fuel column of metal or cermet fuel using liquid sodium as a heat transfer medium. A pump may circulate the liquid sodium through a heat exchanger. The system may include a balance of plant with no nuclear safety function. The reactor may be modular, and may produce approximately 100 MWe.

Abstract: A method is provided for operating a nuclear reactor. The method includes operating the nuclear reactor for an initial cycle during which a core contains initial nuclear fuel assemblies; then operating the nuclear reactor for transition cycles, at least some of the initial nuclear fuel assemblies being progressively replaced, during the replacement steps preceding the transition cycles, with transition nuclear fuel assemblies or with plutonium-equilibrium nuclear fuel assemblies; and then operating the nuclear reactor for at least one plutonium equilibrium cycle during which the core contains only plutonium-equilibrium nuclear fuel assemblies.

Abstract: A spring mounting device in a cladding tube for nuclear fuel, comprising a spring distributor, a spring loader in the cladding tube, the distributor supplying the springs to the loader, said loader comprising a longitudinal slide to receive the spring, a pusher in order to set the spring into place in the cladding tube and is able to move in the slide, means of displacement of said pusher, said device comprising mechanical means in order to associate the actuation of the means of displacement with that of the spring distributor.

Abstract: Cores include different types of control cells in different numbers and positions. A periphery of the core just inside the perimeter may have higher reactivity fuel in outer control cells, and lower reactivity cells may be placed in an inner core inside the inner ring. Cores can include about half fresh fuel positioned in higher proportions in the inner ring and away from inner control cells. Cores are compatible with multiple core control cell setups, including BWRs, ESBWRs, ABWRs, etc. Cores can be loaded during conventional outages. Cores can be operated with control elements in only the inner ring control cells for reactivity adjustment. Control elements in outer control cells need be moved only at sequence exchanges. Near end of cycle, reactivity in the core may be controlled with inner control cells alone, and control elements in outer control cells can be fully withdrawn.

Abstract: The present invention relates generally to nuclear reactors, and more particularly, to nuclear reactors having fuel assemblies that employ support grids. A method of reducing friction and physical contact between a fuel rod and support grid in a nuclear fuel assembly is provided. The method includes applying a lubricant composition to the outer surface of the fuel rod during fuel assembly fabrication and removing the lubricant composition afterward.

Abstract: A method for selecting a loading map for a nuclear reactor core including the following steps: a) providing production data relating to the nuclear fuel assemblies, b) providing neutron data which are representative of the operation of the core, c) calculating the three-dimensional distribution of the local power in the core, d) calculating the extreme value reached by at least one thermomechanical parameter within the nuclear fuel assemblies, and e) selecting, in accordance with the extreme values calculated, a loading map from the loading maps envisaged. A system, computer program and storage medium for selecting a loading map for a nuclear reactor.

Abstract: A nuclear-characteristic calculating program for calculating a nuclear characteristic of a fuel rod that contains nuclear fuel and burnable poison includes a first scattering model that can represent a simple scattering of the neutron and a second scattering model that can represent a complicated scattering of the neutron. The nuclear-characteristic calculating program includes step of calculating, when a burnup of the fuel rod is before a set burnup at which the burnable poison is considered to lose neutron absorption capability, the nuclear characteristic of the fuel rod by using the second scattering model, step of switching, when the burnup of the fuel rod is the set burnup, the scattering model from the second scattering model to the first scattering model, and step of calculating, after performing step of switching, the nuclear characteristic of the fuel rod by using the first scattering model.

Abstract: In a method for improving the energy generating output of a nuclear reactor containing one or more fuel rods in one or more fuel rod bundles while satisfying a maximum subcritical banked withdrawal position (MSBWP) reactivity limit, enrichments of individual fuel rods in an axial cross-section of a lattice being evaluated at the top of the fuel bundle are ranked, and the fuel pins of the highest ranked rod location in the lattice are replaced with pins containing natural uranium. A core simulation is then performed to determine whether there is any margin to a MSBWP reactivity limit. For each lower ranked candidate rod position, the pin replacing and core simulation functions are repeated until no rod location violates the MSBWP reactivity limit, so as to achieve a desired lattice design for the top of the fuel bundle.

Abstract: Most modern integrated circuit transceivers, especially wireless LAN, utilize a direct conversion radio architecture, which is highly advantageous from the perspectives of cost and flexibility, there exist several performance impairments, including gain and phase imbalances between the in-phase (I) and quadrature (Q) of a transmitter or receiver. Disclosed herein is a signal processing methodology and system for compensation of I/Q imbalance for a direct conversion packet-switched OFDM communications system. The imbalance, which accounts for transmitter I/Q imbalance, RX I/Q imbalance, phase/frequency error, and dispersive multipath fading. Both frequency dependent I/Q imbalance and frequency independent cases are considered, covering both wideband and narrowband modulation. The proposed estimation algorithms operate within the fully compliant framework of existing multi-user OFDM radio standards (WLAN, LTE, WimAX).

Abstract: 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.

Abstract: In an initial core of a nuclear reactor, a plurality of water regions having a square cross section for occupying a cross sectional area capable of disposing four fuel assemblies are formed. No fuel assemblies are loaded in these water regions. In the initial core, each fuel assembly is supported by fuel supports. A pressure loss of a first orifice installed in a cooling water supply passage formed in first fuel supports disposed in a central portion of the initial core is larger than that of a second orifice installed in a cooling water supply passage formed in second fuel supports disposed in a peripheral portion surrounding the central portion. Each water region is formed right above a part of the first fuel supports disposed in the central portion. The control rod operation in the nuclear reactor can be simplified by action of cooling water in the water regions.

Abstract: An advanced initial core fuel configuration is for improving the fuel management efficiency and thus economics for a nuclear reactor. A method of implementing such an initial core involves providing a plurality of fuel assemblies having different average enrichments of uranium 235 and arranging the fuel assemblies in an initial core configuration structured to emulate a known equilibrium reload cycle core at least in terms of spatial reactivity distribution. The resulting average enrichment within the initial core ranges from below about 1.0 percent weight of uranium 235 to about 5.0 percent weight of uranium 235. An advanced lattice design is also disclosed.

Abstract: A nuclear installation 10 comprises a cavity 22 which is defined by at least one cavity wall 20 and which is arranged to contain nuclear fuel and a liquid for shielding radiation emitted from the fuel. A barrier 30 is arranged to be deployed within the cavity 22 to define a sub-region 34 within the cavity 20 within which fuel can be contained or transported so as to keep the fuel away from the at least one cavity wall 22 by a predetermined distance. The invention also concerns a method for refuelling a reactor vessel 18.

Abstract: A method is provided for operating a nuclear reactor. The method includes operating the nuclear reactor for at least one plutonium equilibrium cycle during which the core contains plutonium-equilibrium nuclear fuel assemblies; subsequently, operating the reactor for transition cycles, at least some of the plutonium-equilibrium nuclear fuel assemblies being progressively replaced with transition nuclear fuel assemblies and then with uranium-equilibrium nuclear fuel assemblies; and then operating the nuclear reactor for at least one uranium equilibrium cycle.

Abstract: A method is provided for operating a nuclear reactor. The method includes operating the nuclear reactor for an initial cycle during which a core contains initial nuclear fuel assemblies; then operating the nuclear reactor for transition cycles, at least some of the initial nuclear fuel assemblies being progressively replaced, during the replacement steps preceding the transition cycles, with transition nuclear fuel assemblies or with plutonium-equilibrium nuclear fuel assemblies; and then operating the nuclear reactor for at least one plutonium equilibrium cycle during which the core contains only plutonium-equilibrium nuclear fuel assemblies.

Abstract: A method for joint configuration of nuclear power plant fuel includes the following steps: (S1) for at least one operating unit, based on an equilibrium cycle or transition cycle reactor core design, at least one new fuel element is added to at least one operating unit; (S2) after running a combustion cycle, and on basis of the new fuel elements in step (S1), more first spent fuel elements are obtained from the at least one operating unit than are obtained from the equilibrium cycle or transition cycle reactor core design, and said first spent fuel elements are kept in reserve; (S3) for at least one new starting unit, a scheduled number of new fuel elements, as well as the first spent fuel elements obtained for reserve in step (S2), are set in the first reactor cores of at least one new starting unit.

Abstract: The invention relates to a nuclear power station comprising: at least one high temperature reactor; a storage installation (14) for fuel elements (5); means (32) for transferring the fuel elements (5) between the core (4) and the storage installation (14). According to the invention, the transfer means (32) comprise a tunnel (34) for transferring the fuel elements between the reactor core (4) and the storage installation (14).

Abstract: A reactor core, comprising: an outermost region; a core region surrounded by said outermost region; a plurality of fuel support members, each of which is disposed at a lower end portion of said outermost region and said core region; and a plurality of fuel assemblies loaded in said outermost region and said core region and supported by said fuel support members, wherein a plurality of fuel assemblies disposed in said core region include a plurality of first fuel assemblies, each of which is inserted into a first coolant passage which is formed in said fuel support member and has a first resistor having an opening, and a plurality of second fuel assemblies, each of which is individually inserted into each of second coolant passage which is formed in said fuel support member and has a second resistor having an opening and a larger pressure loss than that of said first resistor; and, four fuel assemblies, each of which is adjacent to each of four lateral sides of each of a plurality of first fuel assemblies,

Abstract: A method and apparatus for the permissive control of a mast and fuel grapple to be used in the movement of reactor fuel components, including fuel assemblies, single blade and double blade guides, to be used in a Boiling Water Reactor (BWR) nuclear reactor. The Permissive Control System reduces the chance of human error associated with the movement of reactor components by assisting in controlling the location (plant coordinate) of the mast for picking-up and dropping-off reactor components, the sequence of reactor component movements, the orientation (angular rotation) of the mast and fuel grapple, the raising and lowering of the grapple, and the opening and closing of the fuel grapple.

Abstract: Disclosed embodiments include nuclear fission reactor cores, nuclear fission reactors, methods of operating a nuclear fission reactor, and methods of managing excess reactivity in a nuclear fission reactor.

Abstract: The invention refers to a method for operating a nuclear light water reactor during an operation cycle including a cardinal cycle and a number of successive control rod cycles. The reactor includes a plurality of elongated fuel units containing a nuclear fuel in the form a fissible material, a burnable absorber, and a plurality of control rods introduceable in a respective control rod position. Substantially all control rods are introduced in the core before the reactor is started and an operation cycle is initiated. The reactor is operated during the cardinal cycle with a first control rod configuration with a first group of control rods at least partly introduced and the remaining control rods extracted. The reactor is operated during the subsequent control rod cycles with a respective control rod configuration which each includes a different group of control rods at least partly introduced, wherein the cardinal cycle is substantially longer than each of the subsequent control rod cycles.

Abstract: The present invention relates generally to nuclear reactors, and more particularly, to nuclear reactors having fuel assemblies that employ support grids. A method of reducing friction and physical contact between a fuel rod and support grid in a nuclear fuel assembly is provided. The method includes applying a lubricant composition to the outer surface of the fuel rod during fuel assembly fabrication and removing the lubricant composition afterward.

Abstract: The apparatus for creating and editing a nuclear reactor core template includes a graphical user interface and a processor controlling the graphical user interface to allow a user to selectively populate a loading map with fuel bundles residing in at least one fuel pool.

Abstract: Illustrative embodiments provide for the operation and simulation of the operation of fission reactors, including the movement of materials within reactors. Illustrative embodiments and aspects include, without limitation, nuclear fission reactors and reactor modules, including modular nuclear fission reactors and reactor modules, nuclear fission deflagration wave reactors and reactor modules, modular nuclear fission deflagration wave reactors and modules, methods of operating nuclear reactors and modules including the aforementioned, methods of simulating operating nuclear reactors and modules including the aforementioned, and the like.

Abstract: A method for selecting a loading map for a nuclear reactor core including the following steps: a) providing production data relating to the nuclear fuel assemblies, b) providing neutron data which are representative of the operation of the core, c) calculating the three-dimensional distribution of the local power in the core, d) calculating the extreme value reached by at least one thermomechanical parameter within the nuclear fuel assemblies, and e) selecting, in accordance with the extreme values calculated, a loading map from the loading maps envisaged. A system, computer program and storage medium for selecting a loading map for a nuclear reactor.

Abstract: A handling method for a natural circulation boiling water reactor having a chimney having cylindrical chimney shell disposed above a core in a reactor pressure vessel, a plurality of square tubes disposed in the chimney shell, and a grid support plate with grid holes supporting and in communication with a lower end portion of the square tubes so that adjacent square tubes are disposed at an interval which exceeds the width of one square tube between them. The method includes steps shifting predetermined ones of the square tubes to the interval between the square tubes, and performing maintenance and inspection of members around a core via the grid holes which appear at positions from which the predetermined square tubes are taken out due to the shift of the predetermined square tubes.

Abstract: The apparatus for creating and editing a nuclear reactor core template includes a graphical user interface and a processor controlling the graphical user interface to allow a user to selectively populate a loading map with fuel bundles residing in at least one fuel pool.

Abstract: The core of a pressurized water reactor is assembled in such a way that if the fuel elements on the edge of the core are bent, these fuel elements are oriented such that the bending of the fuel elements points outwards in a convex manner. When the reactor is in operation, forces arise which increase the size of small gaps between the fuel elements at the expense of greater gaps and counteract the bending effect of the fuel elements.

Abstract: A nuclear-powered plant of a portable type with a confinement section where the reaction takes place in a core having a reactive thorium/uranium-233 composition, and where an external neutron source is used as a modulated neutron multiplier for the reactor core output. The core is housed in a containment structure that radiates thermal energy captured in a multiple-paths heat exchanger. The exchanger heat energy output is put to use in a conventional gas-to-water heat exchanger to produce commercial quality steam.

Abstract: The apparatus for creating and editing a nuclear reactor core template includes a graphical user interface and a processor controlling the graphical user interface to allow a user to selectively populate a loading map with fuel bundles residing in at least one fuel pool.

Abstract: A method of fuel bundle consideration in a reactor. The method includes creating or editing bundle groups including fuel bundles.