Abstract: A multi-modular power plant includes a plurality of on-site nuclear power modules that generate a power plant output, and a number of power plant systems which operate using electricity associated with a house load of the power plant. A switchyard associated with the power plant may electrically connect the power plant to a distributed electrical grid. The distributed electrical grid may be configured to service a plurality of geographically distributed consumers. Additionally, the switchyard may electrically connect the power plant to a dedicated electrical grid. The dedicated electrical grid may provide electricity generated from the power plant output to a dedicated service load, and the power plant output may be equal to or greater than a combined load of the dedicated service load and the house load. At least a portion of the power plant output may be distributed to both the power plant systems and the dedicated electrical grid.

Abstract: A multi-modular power plant may include a plurality of on-site nuclear power modules configured to generate a power plant output, wherein one or more of the nuclear power modules may be designated as service module units which are configured to generate a first portion of the power plant output. A remainder of the nuclear power modules may be configured to generate a second portion of the power plant output. A number of power plant systems may be configured to operate using electricity associated with a house load of the power plant, wherein the first portion of the power plant output is equal to or greater than the house load. Additionally, a switchyard may be configured to electrically connect the power plant to a distributed electrical grid. The distributed electrical grid may be configured to service a plurality of geographically distributed consumers, and the switchyard may be configured to apply the second portion of the power plant output to the distributed electrical grid.

Abstract: A pipe restraint assembly includes a restraint body configured to be removably attached to a portion of pipe. The portion of pipe is associated with a postulated pipe failure associated with a release of high pressure fluid. A plurality of apertures penetrate through the restraint body and are positioned proximate to a location of the postulated pipe failure. The apertures are configured to provide a number of passageways for the fluid to exit from the location of the postulated pipe failure and to be released outside of the restraint body. One or more restraint devices maintain the position of the apertures relative to the location of the postulated pipe failure.

Abstract: A cooling system for a reactor module includes a reactor pressure vessel that houses primary coolant and a steam generator that lowers a temperature of the reactor pressure vessel by transferring heat from the primary coolant to a secondary coolant that circulates through the steam generator. The steam generator releases at least a portion of the secondary coolant as steam. Additionally, the cooling system includes a containment vessel that at least partially surrounds the reactor vessel in a containment region. The containment region is dry during normal operation of the reactor module. A controller introduces a source of water into the containment region in response to a non-emergency shut down of the reactor module. The source of water is located external to the containment vessel, and the water is introduced into the containment region after the steam generator has initially lowered the temperature of the reactor pressure vessel in response to releasing the steam.

Abstract: A steam generator tube probe includes a probe head comprising an electronic probe coupled between a proximal portion of the head that is configured for entry into a steam generator tube and a distal portion of the head; and a probe shaft coupled to the distal portion of the shaft and comprising a flexible metallic conduit that comprises a plurality of interlocking portions, each interlocking portion moveably affixed to at least one adjacent interlocking portion.

Abstract: A rod position indication system includes a drive rod operably coupled to a control rod that is configured to be both withdrawn from and inserted into a reactor core. A number of sensing devices are arranged along a path of the drive rod, and an end of the drive rod passes by or through one or more of the sensing devices in response to movement of the control rod relative to the reactor core. The sensing devices are arranged into a plurality of groups, and each group includes two or more of the sensing devices electrically coupled together. The rod position indication system further includes a control rod monitoring device electrically coupled to each group of sensing devices by a routing wire.

Abstract: A support structure for attenuating seismic forces in one or more reactor modules housed in a reactor building includes a mounting structure that may be configured to securely connect the support structure to a floor of the reactor building. A receiving area may be sized to receive a lower portion of a reactor module, and the support structure may be configured to at least partially surround the lower portion of the reactor module within the receiving area. The support structure may further include a retention system located near a top surface of the support structure. The retention system may be configured to contact the reactor module during a seismic event, and an upper portion of the reactor module may extend above the retention system without contacting the support structure.

Abstract: A stable startup system includes a reactor vessel containing coolant, a reactor core submerged in the coolant, and a heat exchanger configured to remove heat from the coolant. The stable startup system further includes one or more heaters configured to add heat to the coolant during a startup operation and prior to the reactor core going critical.

Abstract: A steam generation system may include a plurality of heat transfer tubes configured to circulate a secondary coolant of the steam generation system. The steam generation system may be thermally coupled to a reactor vessel, and the reactor vessel may be configured to house a primary coolant. Heat generated from within the reactor vessel may be transferred from the primary coolant to the secondary coolant. The steam generation system may further include an inclined tube sheet fluidly coupled to the plurality of heat transfer tubes. The inclined tube sheet may be attached to a wall of the reactor vessel in a non-horizontal orientation.

Abstract: A steam generator includes a lower integrated tubesheet and plenum (ITP) configured to receive feedwater and a first set of heat transfer tubes fluidly coupled to a plurality of stubs protruding from a first side of the lower ITP. A second set of heat transfer tubes fluidly couples to plurality of stubs protruding from a second side of the lower ITP. The first set of heat transfer tubes is coiled in a substantially clock-wise direction, and the second set of heat transfer tubes is coiled in a substantially counter-clockwise direction. The steam generator further includes an upper ITP fluidly coupled to the first and second set of heat transfer tubes, wherein the feedwater entering the lower ITP is converted to steam in the first and second sets of heat transfer tubes. The upper ITP is configured to transport the steam away from the steam generator.

Abstract: A spent nuclear fuel rod canister includes a submersible pressure vessel including a casing that defines an interior cavity, the casing including a corrosion resistant and heat conductive material with a thermal conductivity of above about 7.0 watts per meter per kelvin; and a rack enclosed within the interior cavity and configured to support one or more spent nuclear fuel rods.

Abstract: A system for draining a containment vessel may include a drain inlet located in a lower portion of the containment vessel. The containment vessel may be at least partially filled with a liquid, and the drain inlet may be located below a surface of the liquid. The system may further comprise an inlet located in an upper portion of the containment vessel. The inlet may be configured to insert pressurized gas into the containment vessel to form a pressurized region above the surface of the liquid, and the pressurized region may operate to apply a surface pressure that forces the liquid into the drain inlet. Additionally, a fluid separation device may be operatively connected to the drain inlet. The fluid separation device may be configured to separate the liquid from the pressurized gas that enters the drain inlet after the surface of the liquid falls below the drain inlet.

Abstract: A stable startup system includes a reactor vessel containing coolant, a reactor core submerged in the coolant, and a heat exchanger configured to remove heat from the coolant. The stable startup system further includes one or more heaters configured to add heat to the coolant during a startup operation and prior to the reactor core going critical.

Abstract: A stable startup system includes a reactor vessel containing coolant, a reactor core submerged in the coolant, and a heat exchanger configured to remove heat from the coolant. The stable startup system further includes one or more heaters configured to add heat to the coolant during a startup operation and prior to the reactor core going critical.

Abstract: An electrical power system for a nuclear power facility includes an active alternating current (AC) power bus configured to be electrically coupled to a plurality of engineered safety feature (ESF) loads of a plurality of nuclear power systems, each of the ESF loads configured to fail to a safe position upon loss of primary AC power; a critical battery system electrically coupled to the active AC bus, the critical battery system comprising a plurality of valve regulated lead acid (VRLA) batteries; and a primary AC power source electrically coupled to the active AC bus.

Abstract: A system for storing nuclear fuel assemblies includes a plurality of cells housed within a support structure. A first cell may house a first fuel assembly and a second cell may house a second fuel assembly. A plurality of compartments separate the plurality of cells and provide passageways for coolant entering a bottom end of the support structure to remove heat from the nuclear fuel assemblies. A first perforation transfers coolant between the first cell and one or more of the compartments, and a second perforation transfers coolant between the second cell and the one or more compartments. At least a portion of the coolant entering the bottom end of the support structure is transferred between the plurality of cells and the plurality of compartments. Two or more fuel storage racks may be stacked together in alternating fuel patterns to facilitate cooling the fuel assemblies with liquid or air.

Abstract: A system for measuring flow rate within a volume includes one or more transmission devices that transmit one or more signals through fluid contained within the volume. The volume may be bounded, at least in part, by an outer structure and by an object at least partially contained within the outer structure. A transmission device located at a first location of the outer structure transmits a first signal to a second location of the outer structure. A second signal is transmitted through the fluid from the second location to a third location of the outer structure. The flow rate of the fluid within the volume may be determined based, at least in part, on the time of flight of both the first signal and the second signal.

Abstract: A steam generator for a nuclear reactor comprises plenums proximate with a first plane, wherein the first plane intersects a bottom portion of a riser column of a reactor vessel. The steam generator may further comprise plenums proximate with a second plane, approximately parallel with the first plane, wherein the second plane intersects a top portion of the riser column of the reactor vessel. The steam generator may further include a plurality of steam generator tubes that convey coolant from a plenum located proximate with the first plane to one of the plenums proximate with the second plane.

Abstract: A system for monitoring a reactor module housed in a reactor bay may include a mounting structure and one or more extendable attachment mechanisms connected to the mounting structure. Additionally, one or more monitoring devices may be operably coupled to the one or more extendable attachment mechanism, and the one or more extendable attachment mechanisms may be configured to selectively position the one or more monitoring devices at varying distances from a wall of the reactor bay to place the one or monitoring devices in proximity to the reactor module.

Abstract: A steam generator includes a lower integrated tubesheet and plenum (ITP) configured to receive feedwater and a first set of heat transfer tubes fluidly coupled to a plurality of stubs protruding from a first side of the lower ITP. A second set of heat transfer tubes fluidly couples to plurality of stubs protruding from a second side of the lower ITP. The first set of heat transfer tubes is coiled in a substantially clock-wise direction, and the second set of heat transfer tubes is coiled in a substantially counter-clockwise direction. The steam generator further includes an upper ITP fluidly coupled to the first and second set of heat transfer tubes, wherein the feedwater entering the lower ITP is converted to steam in the first and second sets of heat transfer tubes. The upper ITP is configured to transport the steam away from the steam generator.