Abstract: A nuclear plant includes a nuclear reactor, a containment structure that at least partially defines a containment environment of the nuclear reactor, and a passive containment cooling system that causes coolant fluid to flow downwards from a coolant reservoir to a bottom of a coolant channel coupled to the containment structure and rise through the coolant channel toward the coolant reservoir due to absorbing heat from the nuclear reactor. A check valve assembly, in fluid communication with the coolant reservoir, selectively enables one-way flow of a containment fluid from the containment environment to the coolant reservoir, based on a pressure at an inlet being equal to or greater than a threshold magnitude. A fusible plug, in fluid communication with the coolant reservoir at a bottom vertical depth below the bottom of the coolant reservoir, enables coolant fluid to flow into the containment structure based on at least partially melting.

Abstract: Combined cleanup and heat sink systems work with nuclear reactor coolant loops. Combined systems may join hotter and colder sections of the coolant loops in parallel with any steam generator or other extractor and provide optional heat removal between the same. Combined systems also remove impurities or debris from a fluid coolant without significant heat loss from the coolant. A cooler in the combined system may increase in capacity or be augmented in number to move between purifying cooling and major heat removal from the coolant, potentially as an emergency cooler. The cooler may be joined to the hotter and colder sections through valved flow paths depending on desired functionality. Sections of the coolant loops may be fully above the cooler, which may be above the reactor, to drive flow by gravity and enhance isolation of sections of the coolant loop.

Abstract: Clamps can be secured to a slip joint and limit flow through the same by seating on a diffuser axially regardless of wear and damage in the slip joint. An extension from the clamp seats to the inlet mixer. These extensions can be adjusted from outside the clamp to achieve an individual preload or flow limitation through the slip joint. The extension may be an O-ring or other shape. A biasing drive may connect to and move the extension from an outside surface of the clamp. The biasing drive may include a threaded cap in an outer groove that is linked to a plunger via a spring. Clamps are fabricated of materials that maintain their physical properties when exposed to an operating nuclear reactor environment and may be relatively rigid and resilient metals.

Abstract: According to at least some example embodiments, a dome collector separation stage includes an inner side wall that defines an inner channel; and an outer side wall that, together with the inner side wall, defines an outer channel, the inner channel being configured to receive a two-phase flow stream (FS) of water and steam, and pass the two-phase FS to the outer channel via inlets included in the inner side wall, the outer channel being configured to separate at least some water from the two-phase FS, and pass moisture-reduced steam out of the steam separator stage via outlets included in the outer side wall.

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: 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: Steam generators in power plants exchange energy from a primary medium to a secondary medium for energy extraction. Steam generators include one or more primary conduits and one or more secondary conduits. The conduits do not intermix the mediums and may thus discriminate among different fluid sources and destinations. One conduit may boil feedwater while another reheats steam for use in lower and higher-pressure turbines, respectively. Valves and other selectors divert steam and/or water into the steam generator or to other turbines or the environment for load balancing and other operational characteristics. Conduits circulate around an interior perimeter of the steam generator immersed in the primary medium and may have different cross-sections, radii, and internal structures depending on contained. A water conduit may have less flow area and a tighter coil radius. A steam conduit may include a swirler and rivulet stopper to intermix water in any steam flow.

Abstract: Vibration-based flowmeters are useable in inaccessible nuclear reactor spaces. Pipe-organ-type flowmeters include a passage with an opening constricted, and subsequent widening section. An extension and outlet that create turbulence in the flow at the outlet create a standing wave and vibration in the extension and/or entire flowmeter. A flow rate of the fluid through the flowmeter can be calculated using length of the passage and/or known properties of the fluid. Multiple flowmeters of customized physical properties and types are useable together.

Abstract: A nuclear plant includes a nuclear reactor, a containment structure that at least partially defines a containment environment of the nuclear reactor, and a passive containment cooling system that causes coolant fluid to flow downwards from a coolant reservoir to a bottom of a coolant channel coupled to the containment structure and rise through the coolant channel toward the coolant reservoir due to absorbing heat from the nuclear reactor. A check valve assembly, in fluid communication with the coolant reservoir, selectively enables one-way flow of a containment fluid from the containment environment to the coolant reservoir, based on a pressure at an inlet being equal to or greater than a threshold magnitude. A fusible plug, in fluid communication with the coolant reservoir at a bottom vertical depth below the bottom of the coolant reservoir, enables coolant fluid to flow into the containment structure based on at least partially melting.

Abstract: Control rod drives include linearly-moveable control elements inside an isolation barrier. Control rod drives move the control element through a motor and rotor powering a linear screw internal to an isolation barrier. Induction coils may generate magnetic fields and be moveable across a full stroke length of the control element in the reactor. The magnetic fields hold closed a releasable latch to disconnect the control elements from the linear drives. A control rod assembly may join to the control element. The control rod assembly may lock with magnetic overtravel latches inside the isolation barrier to maintain an overtravel position. Overtravel release coils outside the isolation barrier may release the latches to leave the overtravel position. Operation includes moving the magnetic fields and releasable latch together on opposite sides of an isolation barrier to drive the control element to desired insertion points, including full insertion by gravity following de-energization.

Abstract: Passive safety systems cool reactors using surrounding ground as a heat sink. A coolant flow channel may loop around the reactor and then pass outside, potentially through a containment building, into surrounding ground. No active components need be used in example embodiment safety systems, which may be driven entirely by gravity-based natural circulation. The coolant loop may be air-tight and seismically-hardened and filled with any coolant such as water, air, nitrogen, a noble gas, a refrigerant, etc. The ground may include a soil of grey limestone, soft grey fine sandy clay, grey slightly silty sandy gravel, etc. or any other fill with desired heat-transfer characteristics. Coolant fins and/or jackets with secondary coolants may be used on the coolant loop. The coolant loop may be buried at any constant or variable depth, and the reactor and containment may also be buried in the ground.

Abstract: A nuclear reactor facility may include a reactor building, a reactor vessel housed within the reactor building, and an auxiliary cooling system integrated with the reactor building. The reactor building has a visible section above a ground level and a buried section below the ground level. The reactor vessel contains a fuel core and is housed within the buried section of the reactor building below the ground level. The auxiliary cooling system includes a plurality of ducts integrated with the reactor building and is configured to passively cool the reactor vessel via natural air circulation.

Abstract: A nuclear power plant includes a nuclear structure, a frontline support equipment, and a support structure. The nuclear structure includes, and is configured to protect from incurring damage due to a damaging event, at least one of a nuclear reactor or a nuclear fuel storage. The frontline support equipment is configured to perform a fundamental safety function. The support structure is spatially separate from the nuclear structure and includes an initiating support equipment configured to trigger the frontline support equipment to perform the fundamental safety function such that the fundamental safety function is performed independently of the initiating support equipment subsequent to the triggering. The support structure may be a non-protected structure that is not configured to protect the initiating support equipment from incurring damage due to the damaging event.

Abstract: A nuclear plant including a nuclear reactor and a natural circulation air cooling system configured to provide cooling of the nuclear reactor based on circulating ambient air from an air inlet opening to absorb nuclear reactor rejected heat through an outlet air opening, due to natural circulation of said ambient air induced by the ambient air absorbing said rejected heat, may further include a pile structure covering at least one opening of the air inlet opening or the air outlet opening. The pile structure may include a pile of packing objects covering the at least one opening, such that the at least one opening is obscured from direct exposure to the ambient environment by the pile of the packing objects.

Abstract: Casks shield materials and passively remove heat via heat transport paths from deep inside to outside the cask. The transport path may be heat pipes and conductive rods that are non-linear so that radiation is always shielded by the cask. A damper may surround an end of the heat transport path to control heat loss from the cask. A jacket of fluid or meltable material that conducts heat by convection may surround stored materials ensure an even temperature within the cask, and the heat transport path may absorb heat from the jacket. Casks are useable to safely store, transport, and dispose of any sensitive or heat-generating material. Casks may be opened or closed to simultaneously load and offload materials at a consistent operating temperature provided by heaters in the cask.

Abstract: A remote pulse TDR liquid level measurement system and method may include inserting a probe into a body of water. The probe has a probe/air interface, and the body of water includes an air/water interface. A narrow pulse is remotely transmitted to the probe via a coaxial cable. A first impedance mismatch is received from the probe/air interface in a form of a positive reflected pulse, and a second impedance mismatch is received from the air/water interface in a form of a negative reflected pulse. A time between the positive reflected pulse and the negative reflected pulse is calculated, and the time is converted to a distance, the distance being indicative of the water level.

Abstract: A combined blade guide and exchange tool, include a blade guide tool having a lower end and an upper end and a plurality of frame rails supporting a pair of lower collet housings at a lower end of the blade guide tool. A pair of fuel support grapple actuating rods are supported between the plurality of frame rails and have a first end engaging a pair of collets within the pair of lower collet housings and a second end disposed at the upper end of the blade guide tool. A blade exchange tool is releasably mounted to the upper end of the blade guide tool and includes a pair of upper collets for engaging the pair of fuel support grapple actuating rods. The blade exchange tool further including a slider and hook assembly attached to a cable guided by the blade exchange tool and adapted for engaging a control rod.

Abstract: A method of cleaning a jet pump assembly of a nuclear reactor may comprise inserting a cleaning tool into the jet pump assembly such that a front face of the cleaning tool is adjacent to an inner surface of the jet pump assembly and below a level of a first liquid in the jet pump assembly. The method may additionally comprise directing a plurality of front jets of a second liquid from a plurality of front orifices on the front face of the cleaning tool such that the plurality of front jets of the second liquid strikes the inner surface of the jet pump assembly. The method may further comprise maintaining a standoff distance between the front face of the cleaning tool and the inner surface of the jet pump assembly during the cleaning of the jet pump assembly.

Abstract: Various example embodiments are directed towards an improved control drum, as well as systems, apparatuses, and/or methods for operating a nuclear reactor with a plurality of improved control drums. The control drum includes an outer shell, an inner shell, a plurality of tubes, the plurality of tubes including at least one neutron absorbing tube and at least one neutron scattering tube, and at least one baffle plate arranged between the outer shell and the inner shell, the at least one baffle plate including a plurality of perforations, and at least one perforation of the plurality of perforations configured to support a tube of the plurality of tubes.

Abstract: An integrated passive cooling containment structure for a nuclear reactor includes a concentric arrangement of an inner steel cylindrical shell and an outer steel cylindrical shell that define both a lateral boundary of a containment environment of the nuclear reactor that is configured to accommodate a nuclear reactor and an annular gap space between the inner and outer steel cylindrical shells, a concrete donut structure at a bottom of the annular gap space, and a plurality of concrete columns spaced apart azimuthally around a circumference of the annular gap and extending in parallel from a top surface of the concrete donut structure to a top of the annular gap space. The outer and inner steel cylindrical shells and the concrete donut structure at least partially define one or more coolant channels extending through the annular gap space.