Abstract: A system for injecting hydrogen into Boiling Water Reactor (BWR) reactor support systems in operation during reactor startup and/or shutdown. The system the hydrogen injection system includes at least one hydrogen source, flow control equipment, and pressure control equipment. The pressure control equipment being configured to regulate a pressure of a hydrogen flow between the at least one hydrogen source and the at least one first BWR support system based upon an operating pressure of the at least one first BWR support system.

Abstract: A chimney of a nuclear reactor may include a hollow body with an interior surface and an opposing exterior surface; and a plurality of trip structures on the exterior surface of the hollow body. The chimney may be used in a method of improving a core inlet enthalpy of a nuclear reactor. The method may include interrupting a downward flow of water within a downcomer region of a reactor pressure vessel with a plurality of first trip structures. The downcomer region is an annular space defined by the reactor pressure vessel and a chimney within the reactor pressure vessel. The plurality of first trip structures are disposed on an exterior surface of the chimney.

Abstract: A pyrotechnic-actuated valve assembly may include an insert body having an inlet, an outlet, and a flow path extending from the inlet to the outlet. The insert body is formed of a first alloy. A shear structure is bonded to the outlet of the insert body so as to close the flow path. The shear structure is formed of a second alloy. The second alloy of the shear structure is bonded to the first alloy of the insert body so as to form a hermetic seal. The dual-alloy nature of the valve assembly allows a relatively clean shearing of the shear structure during actuation, thus reducing or preventing the occurrence of deformation and/or material fragments in the flow path.

Abstract: An insulated solution injector may include an outer tube and an inner tube arranged within the outer tube. The outer tube and the inner tube may define an annular space therebetween, and the inner tube may define a solution space within. The annular space may be configured so as to insulate the solution within the solution space. As a result, the solution may be kept to a temperature below its decomposition temperature prior to injection. Accordingly, the decomposition of the solution and the resulting deposition of its constituents within the solution space may be reduced or prevented, thereby decreasing or precluding the occurrence of a blockage.

Abstract: A reinforcement assembly may be provided for a bracket configured to constrain a cooling pipe of a spent fuel pool of a nuclear reactor. The reinforcement assembly includes a base structure defining back slots, angled slots, side slots, and/or front slots. Back boss structures may be configured to slidably engage with the back slots of the base structure. Pipe boss structures may be configured to slidably engage with the angled slots of the base structure. Side clamps may be configured to slidably engage with the side slots of the base structure. Each of the side clamps may define a vertical slot. Vertical clamps may be configured to slidably engage with the vertical slot of each of the side clamps. Front clamps may be configured to slidably engage with the front slots of the base structure.

Abstract: A reactor pressure vessel includes a reactor pressure vessel body, a nozzle structure connected to the reactor pressure vessel body, a conduit structure connected to the nozzle structure, and a restraint device attached around a portion of the conduit structure. The restraint device includes collar parts that have cross sections corresponding to respective segments of a periphery of the portion of the conduit structure, brackets attached to the nozzle structure, and rods connecting the brackets to the collar parts. The collar parts are connected end-to-end to each other such that a cross section of the collar parts connected to each other corresponds to the periphery of the portion of the conduit structure. The collar parts are pinned to each other. The brackets spaced apart from each other around a periphery of the nozzle structure.

Abstract: An entrainment-reducing assembly may include a container configured to hold a liquid. A venting arrangement may extend into an upper portion of the container and be configured to direct condensable and non-condensable gases into the container. A suction structure may extend into a lower portion of the container and be configured to carry out an extraction of excess liquid from the container caused by condensed gases. A deflector may be disposed between the suction structure and the venting arrangement within the container. As a result, an entrainment of uncondensed gases during the extraction of the liquid by the suction structure may be reduced or prevented, thereby protecting the pump from cavitation and failure.

Abstract: A sodium-cooled nuclear reactor includes at least one electromagnetic pump assembly and a backflow reduction pipe. The backflow reduction pipe may include an inlet, an outlet, at least one tubular section having a first length and a first diameter, and at least one fluid diode section between the inlet and the outlet.

Abstract: Seals are positioned between abutting nuclear reactor components. Example seals are held in position by gravity, grooves, retainers, direct joining, or other mating structures to seal the abutting components. Compression of example seals drives the seals against the joining components, preventing fluid passage therebetween. Example seals may include a cavity opening to a higher pressure fluid outside the joined components to drive expansion or sealing of the seal. Seals may have a C-shaped, E-shaped, O-ring, coiled, helical, or other cross-section to provide such a cavity. Example seals may be flexible materials compatible with radiation and heat encountered in a nuclear reactor. Seals may be continuous or sectional about the abutment of the components. An annular seal may extend continuously around a perimeter of removably joined core plates, supports, shrouds, and/or chimney heads and structures. Seals can be installed between and in the components at any time access is available to the components.

Abstract: A jet pump slip joint repair assembly includes at least one clamp and a bushing configured to be inserted in a bore of a diffuser and to surround a portion of an inlet mixer. The clamp includes a gripping surface and a gripping collar. The bushing includes a generally cylindrical sidewall, the sidewall configured to surround the portion of the inlet mixer, a grooved flange on an upper surface of the sidewall, at least one cutout between adjacent portions of the grooved flange, and a groove on an inner, bottom surface of the sidewall. The assembly also includes a seal in the groove. The seal is flexible and formed of a metallic material. The seal is configured to be compressed when the at least one clamp engages the bushing.

Abstract: Methods implemented by at least one electronic processor for generating pointwise fast neutron spectra may include receiving composition data; receiving source data or calculating the source data; receiving nuclear data; and calculating the pointwise fast neutron spectrum based on numerical integration using the composition, source, and nuclear data. Systems for generating pointwise fast neutron spectra may include a bus; at least one electronic processor connected to the bus; an input device connected to the bus; and a communication link connected to the bus. The at least one electronic processor may be configured to receive composition data from the input device via the bus, to receive source data from the input device via the bus or to calculate the source data, to receive nuclear data from the communication link via the bus, and to calculate the pointwise fast neutron spectrum based on numerical integration using the composition, source, and nuclear data.

Abstract: A breaker valve assembly for a nuclear reactor containment includes a valve body, a valve body insert, and a lid. The valve body includes a first side wall defining a chamber, a first opening in a top portion of the first side wall, and a second opening in a bottom portion of the first side wall. The second opening communicates with the first opening of the valve body. The valve insert body includes a second side wall defining a second chamber, and a third opening in a bottom portion of the second side wall. The valve insert body is nested in the valve body. The lid is arranged on an upper edge of the side wall of the valve insert body. The valve insert body is configured to move substantially vertically with respect to the valve body.

Abstract: A reinforcement assembly may be provided for a bracket configured to constrain a cooling pipe of a spent fuel pool of a nuclear reactor. The reinforcement assembly includes a base structure defining back slots, angled slots, side slots, and/or front slots. Back boss structures may be configured to slidably engage with the back slots of the base structure. Pipe boss structures may be configured to slidably engage with the angled slots of the base structure. Side clamps may be configured to slidably engage with the side slots of the base structure. Each of the side clamps may define a vertical slot. Vertical clamps may be configured to slidably engage with the vertical slot of each of the side clamps. Front clamps may be configured to slidably engage with the front slots of the base structure.

Abstract: A fuel bundle temperature sensing device may include an indicating rod made of a first material; an outer housing having an upper opening, the outer housing being made of a second material and surrounding at least a portion of the indicating rod; and a rod holder attached to an inner surface of the outer housing, the rod holder being made of a third material and being configured to support the indicating rod such that a top surface of the rod extends out of the upper opening of the outer housing, the third material having a lower melting point than the first and second materials.

Abstract: A method and system for external alternate suppression pool cooling for a Boiling Water Nuclear Reactor (BWR) that does not breach the Mark I primary containment. The external cooling system may include a heat sink fluidly coupled to cooling coils surrounding the suppression pool. Cool water may be pumped through the cooling coils without the need for normal plant electrical power, which is ideal during a plant emergency. The cooling system may also be operated and controlled from a remote location to protect the safety of plant personnel.

Abstract: A sodium-cooled nuclear reactor includes at least one electromagnetic pump assembly and a backflow reduction pipe. The backflow reduction pipe may include an inlet, an outlet, at least one tubular section having a first length and a first diameter, and at least one fluid diode section between the inlet and the outlet.

Abstract: A passive safety system for removing decay heat from a nuclear power system may comprise a shroud structure and a heat generator that is within the shroud structure. A thermoelectric device may be disposed in thermal contact with the heat generator. The thermoelectric device is configured to generate a voltage based on a temperature difference between opposite parts of the thermoelectric device. A fan arrangement is disposed above the heat generator and in electrical connection with the thermoelectric device. The fan arrangement is configured to increase a coolant flow through the coolant passage to the outlet opening based on the voltage from the thermoelectric device.

Abstract: A sodium-cooled nuclear reactor includes at least one electromagnetic pump assembly and a backflow reduction pipe. The backflow reduction pipe may include an inlet, an outlet, at least one tubular section having a first length and a first diameter, and at least one fluid diode section between the inlet and the outlet.

Abstract: A generator is installed on and provides electrical power from a turbine by converting the turbine's mechanical energy to electricity. The generated electrical power is used to power controls of the turbine so that the turbine can remain in use through its own energy. The turbine can be a safety-related turbine in a nuclear power plant, such that, through the generator, loss of plant power will not result in loss of use of the turbine and safety-related functions powered by the same. Appropriate circuitry and electrical connections condition the generator to work in tandem with any other power sources present, while providing electrical power with properties required to safely power the controls.

Abstract: An inspection apparatus may include an installation platform and a scan head. The scan head may be configured to engage in an index movement, a theta movement, a wrist fold movement, and a scan movement. During the scan movement, a transducer of the scan head travels a circumferential path so as to allow an inspection of a surface that is opposite of a surface on which the installation platform is mounted. The inspection apparatus may be used to inspect a reactor component in a nuclear reactor.