Abstract: There is provided a swim-in-place spa, comprising a basin for containing water, a circulation subsystem having a primary conduit extending from an inlet in the basin, a pump fluidly connected to the primary conduit to pump water from the inlet, a swim-in-place jet affixed to the basin, and a secondary conduit extending from the pump to the swim-in-place jet, in operation the pump inducing a flow of water toward the swim-in-place jet. The swim-in-place jet has a nozzle and a diffuser downstream of the nozzle relative to the flow of water, a nozzle outlet smaller than a diffuser inlet, the nozzle outlet and the diffuser inlet disposed in a spaced-apart relationship defining a gap for receiving a flow of entrained water. The circulation subsystem is configured for creating a water jet matching a cross-section of a swimmer.

Abstract: Systems repair jet pump elbow joining structures like RS1 and RS2 welds. Systems include a base having legs that secure to ends of the elbow in different directions, and a drive plate that joins to flow conduits where they meet the elbow. The drive plate and base may then be pushed together, resulting in compression or joining of the elbow and flow conduit. Multiple drive plates may be used with a single base to compress multiple flow conduits to the base. The base and the drive plates can be driven together with a driving bolt extending through the base and driving plate. To provide a better fit, grooves can be created in the flow conduits through machining from the installed base. The drive plate may be seated into the groove to achieve a desired orientation with less slippage. Example embodiments and methods do not require welding or a welding base.

Abstract: A method for heating primary coolant in a nuclear supply system in one embodiment includes filling a primary coolant loop within a reactor vessel and a steam generating vessel that are fluidly coupled together with a primary coolant, drawing a portion of the primary coolant from the primary coolant loop and into a start-up sub-system, heating the portion of the primary coolant to form a heated portion of the primary coolant, and injecting the heated portion of the primary coolant back into the primary coolant loop. The primary coolant may be heated to a no-load operating temperature.

Abstract: A method of repairing a slip joint on a jet pump assembly between an inlet mixer and a diffuser, with the diffuser having an opening that receives the inlet mixer with a given spacing between an outside diameter of the inlet mixer and an inside diameter of the opening in the diffuser forming an annulus whose spacing is a product of manufacture and vibration wear. The method comprises the steps of remotely accessing the annulus and narrowing a radial dimension of the annulus.

Abstract: A bolt fixing device is configured so that a lock cap is pushed up by elastic force of an elastic member and engages upper surface teeth with lower surface teeth, the upper surface teeth being formed on the upper surface of a flange of a lock cap, the lower surface teeth being formed on the lower surface of an engagement flange of a body housing. Thus, the head bolt of a jet pump beam is fixed. With the configuration, when installing an inlet mixer, the head bolt of the jet pump beam is simply and reliably locked against rotation.

Abstract: A lock plate for a locking device of a jet pump beam, the locking device including a locking sleeve including a lower portion, may include a beam bolt opening sized to receive the locking sleeve, and a spring arm including plurality of spring a ratchet teeth sized to mesh with locking sleeve ratchet teeth included in the lower portion of the locking sleeve, the spring arm being structured such that the spring arm has both i) an engaged position where the locking sleeve is in the beam bolt opening and at least a portion of the capture feature overlaps vertically with an upper surface of the lower portion of the locking sleeve, and ii) a disengaged position where the locking sleeve is in the beam bolt opening and the capture feature does not overlap vertically with the upper surface.

Abstract: A jet pump beam (hereinafter, referred to as a beam) is fitted into a pair of projecting portions installed to a transition piece, and after the beam is arched, a beam bolt engaged with the beam is tightened. An end of the beam bolt comes in contact with a top surface of an insert member fitted into an elbow disposed between the pair of projecting portions. An ultrasonic sensor head is fixed to the beam bolt, and ultrasonic waves are sent to the beam bolt from the ultrasonic sensor in the ultrasonic sensor head. An ultrasonic measuring apparatus obtains echo intensity of each of reflected waves generated at the end of the beam bolt and a bottom surface of the insert member, and based on the echo intensities, an echo intensity ratio R is calculated. The installed state of the beam is checked using the echo intensity ratio R.

Abstract: A method and apparatus for providing a Boiling Water Reactor (BWR) jet pump three point slip joint clamp to mitigate sleep joint leakage flow induced vibration of a BWR jet pump assembly. A collar, provided as one seamless component or in separate portions, is installed on the upper crown of a diffuser. The collar includes a lower set of fasteners and an upper set of fasteners that contact the inlet mixer and diffuser, respectively, to horizontally stabilize the inlet mixer in a fixed position inside of the diffuser. The upper fasteners may be anchored by bosses that ensure a light-weight design of the collar. An optional cantilevered seal (including a cantilevered overhang and a lip) may mitigate leakage from the slip joint interface.

Abstract: A jet pump measuring pipe repair method that repairs a ruptured part of a measuring pipe horizontally installed to a lower portion of a jet pump provided in reactor water inside a reactor pressure vessel. The repair method includes: fixing a support member to the jet pump near the measuring pipe left remained; mounting, after the support member fixing, a measuring pipe connector provided with a pipe-repairing pipe having both ends over which connecting pipes are fitted, respectively, to the support member; connecting, after the connector mounting, the remaining measuring pipe and connecting pipe using the measuring pipe connector.

Abstract: A jet pump beam is made of improved heat-treated precipitation-hardened nickel base alloy excellent in anti-stress corrosion cracking properties and high-temperature strength, and having high ductility and a high elastic modulus. A jet pump beam 27 made of improved heat-treated nickel base alloy is produced by preparing a precipitation-strengthened nickel base alloy material having a component composition containing by mass %, Ni: 50.0% to 55.0%, Cr: 17.0% to 21.0%, Nb+Ta: 4.75% to 5.50%, Mo: 2.8% to 3.3%, Ti: 0.65% to 1.15%, Al: 0.2% to 0.8%, C: 0.08% or less, Mn: 0.35% or less, Si: 0.35% or less, S: 0.015% or less, P: 0.03% or less, Cu: 0.30% or less, B: 0.006% or less, and Co: 1.0% or less, and Fe and inevitable impurities constituting a remaining part, subjecting the nickel base alloy material to solution heat treatment at a temperature of 1010° C. to 1090° C., and subjecting the nickel base alloy material to age-hardening heat treatment at a temperature of 694° C. to 714° C.

Abstract: A jet pump which can restrain self-excited vibration in a connection portion between an inlet mixer pipe and a diffuser pipe without inhibiting a structural deformation due to thermal expansion and the like includes a slip joint structure connecting the inlet mixer pipe and the diffuser pipe to each other by inserting the inlet mixer pipe into an upper end opening of the diffuser pipe with a clearance left therebetween; and a self vibration damping structure configured such that when the clearance defined by an outer pipe wall of the inlet mixer pipe and an inner pipe wall of the diffuser pipe is widening or narrowing due to vibration of the inlet mixer pipe or the diffuser pipe, a flow path resistance inside a clearance flow path for pumped coolant water defined by the clearance is not smaller than a fluid inertia force all over the clearance flow path.

Abstract: Disclosed are various wedges that may be used in a restrainer bracket of a jet pump assembly. The jet pump assembly may include a restrainer bracket having an upper bracket and a lower bracket connected to an inlet mixer. A wedge may be provided between the upper bracket and the lower bracket and a wedge rod may pass through a slotted hole of the wedge. Ends of the wedge rod may be attached to the upper and lower brackets. The restrainer bracket may further include a yolk-like member which surrounds the inlet mixer and is connected to a riser pipe. The wedge may include an inclined surface which is configured to engage with a restrainer bracket pad of the yolk-like member. The wedges may further include inner curved surfaces which contact the wedge rod and the inner curved surfaces may be part of an insert that may be inserted in the wedge.

Abstract: A lock plate for a locking device of a jet pump beam, the locking device including a locking sleeve including a lower portion, may include a beam bolt opening sized to receive the locking sleeve, and a spring arm including plurality of spring a ratchet teeth sized to mesh with locking sleeve ratchet teeth included in the lower portion of the locking sleeve, the spring arm being structured such that the spring arm has both i) an engaged position where the locking sleeve is in the beam bolt opening and at least a portion of the capture feature overlaps vertically with an upper surface of the lower portion of the locking sleeve, and ii) a disengaged position where the locking sleeve is in the beam bolt opening and the capture feature does not overlap vertically with the upper surface.

Abstract: A method and apparatus for a Boiling Water Reactor (BWR) jet pump inlet mixer support that provides rigid support for inlet mixers. The inlet mixer support attaches to a conventional BWR jet pump assembly to pull the inlet mixer away from the centerline of a riser pipe or maintain the existing inlet mixer position. The inlet mixer support may provide redundant support that may otherwise be provided by set screws of a conventional restrainer assembly. The inlet mixer support may, alternatively, be used in lieu of conventional set screws. The inlet mixer support may also counter-act additional side loading that may be applied to inlet mixers to stabilize inlet mixer movement and vibration when the BWR jet pump assembly is in operation. Optionally, the inlet mixer support may also prevent removal of existing restrainer bracket set screws.

Abstract: A method and apparatus for physically restraining an inlet mixer of a boiling water reactor (BWR) jet pump assembly. An inlet mixer clamp assembly is attached to the top of a transition piece of the BWR jet pump assembly, to provides a downward clamping force on the top of the inlet mixer. The clamping force restrains the inlet mixer from experiencing vibration and mitigates leakage between the inlet mixer and the transition piece sealing surfaces of the jet pump assembly. The clamping force also restrains the inlet mixer from undesirable rotation, especially during operation of the jet pump assembly. The inlet mixer clamp assembly may be used as an alternative to conventional jet pump beam assemblies. Alternatively, the inlet mixer clamp assembly may be used as a redundant physical restraint in addition to the conventional jet pump beam assemblies.

Abstract: A retainer provided at lower portion of a pump beam of a jet pump for circulating cooling water to a reactor core or a bolt for fastening the retainer is cut through an underwater-remote control to remove the bolt and the retainer is removed through the underwater-remote control.

Abstract: An apparatus for reinforcing a jet pump riser includes: an elbow upper clamp for covering a riser elbow coupled to a thermal sleeve from an upper side thereof; an elbow lower clamping member for clamping the riser elbow from a lower side thereof; an elbow vertical portion clamping member for covering a vertical portion of the riser elbow; and an elbow horizontal portion clamping member for covering a horizontal portion of the riser elbow. These members are disposed in different orientations with respect to the elbow upper clamp so as to fix the thermal sleeve, the riser elbow and the riser pipe.

Abstract: A jet pump has a plurality of nozzles installed to a nozzle base, a throat and a diffuser. A first nozzle straight-tube portion, a first nozzle narrowing portion, a second nozzle straight-tube portion, a second nozzle narrowing portion, and a nozzle lower end portion formed in those nozzles are disposed in this order from the nozzle base to a ejection outlet. A narrowing angle of the second nozzle narrowing portion is larger than of the first nozzle narrowing portion. The jet pump forms, in a lower end portion of the throat, a flow passage narrowing portion having a flow passage cross-sectional area that gradually diminishes. This flow passage narrowing portion is inserted into an upper end portion of the diffuser.

Abstract: Hard stops are useable in an operating nuclear reactor to separate and bias restrainer brackets and inlet mixers. Hard stops include a lip clamp that clamps to a restrainer bracket and a wedge member that biases against the inlet mixer. The wedge member and lip clamp are engaged such that the two components can slide against one another to bias the restrainer bracket and inlet mixer. The lip clamp includes a clamp arm and an engagement member to clamp opposite sides of the restrainer bracket. Ratchet assemblies maintain selective positioning various components of the hard stops. Hard stops may be used in several different numbers, positions, and configurations in repair or modification systems. Hard stops may be installed by determining location on an outside of a restrainer bracket for the hard stop, securing the hard stop at the location, and biasing the hard stop between two components at the location.

Abstract: A support clamp assembly for mechanically securing a thermal sleeve to an elbow conduit in a jet pump of a nuclear reactor vessel, the support clamp assembly including: a tension shaft having a first end extendable through an opening in a sidewall of the elbow conduit and an opposite end with a head; a cruciform assembly having a base with an opening to receive the tension shaft and to abut the head of the shaft, wherein the cruciform assembly seats in the thermal sleeve; a boss slidable over the first end of the tension shaft and having a curved surface seating an outside surface of the elbow conduit, and a coupling device engaging the first end of the tension shaft and abutting the boss, wherein the coupling device places the tension shaft under tension to secure the cruciform assembly to the thermal sleeve and the boss to the elbow conduit.

Abstract: An auxiliary wedge positioning apparatus/assembly 100 for use in a nuclear reactor pressure vessel 12 having riser piping 44 and 144 and a jet pump assembly 46 and 120, the apparatus 100 having a combination slide wedge 105 and spring 103 mounted on a restraint bracket body 102 having a transverse rail 110 with end gull-wing hooked protrusions 111 with sections 150, 152, 156 and wing stability attachment 155, the slide wedge used for placement between the riser piping 44 and 144 and jet pump assembly 46 and 120 to control vibrations during operation of the reactor vessel 12.

Abstract: A method and apparatus for providing a Boiling Water Reactor (BWR) jet pump inlet-mixer integral slip joint clamp to constrain the inlet mixer and diffuser to mitigate inlet mixer flow induced vibration of a BWR jet pump assembly. The slip joint clamp includes horizontally projecting flanges with vertical sidewalls that protrude toward a lowest distal end of the inlet mixer. Fasteners penetrating the flanges provide a biasing load on the diffusers by being tightened to press against an upper crown on the diffuser. One or more flanges may be used. Laterally disposed gaps between the flanges may provide a clearance for guide ears of the diffuser to fit between the flanges.

Abstract: A slip joint of the jet pump assembly inlet-mixer is the interface between a diffuser and an inlet-mixer. The diffuser is coated with a first hardfacing alloy, and the inlet-mixer is coated with a second hardfacing alloy different from the first hardfacing alloy. The first hardfacing alloy may be a cobalt-based alloy and the second hardfacing alloy may be a cobalt-free alloy, i.e., at least one of an iron-based and nickel-based hardfacing alloy.

Abstract: An apparatus for controlling movement of a first component integrated with a second component may include a first clamp configured to engage the first component, a second clamp configured to engage the second component, and a plurality of connectors configured to connect the first and second clamps. The connectors may allow movement of the first clamp relative to the second clamp in a first direction between the first and second clamps. The connectors may limit movement of the first clamp relative to the second clamp in a second direction perpendicular to the first direction.

Abstract: Disclosed are various torsional restraint systems for torsionally restraining a jet pump assembly, wherein the jet pump assembly includes a riser pipe, a transition assembly on the riser pipe, and a restrainer bracket connecting a first and a second inlet mixer to the riser pipe. The torsional restraint system includes a first contact member operatively attached to a side of the jet pump assembly and a second contact member operatively attached to the side of the jet pump assembly and disposed from the first contact member such that the first and second contact members restrain the riser pipe from rotating about a centerline of the riser pipe.

Abstract: A jet pump sensing line support clamp may be used for sensing line repair, replacement, and damage prevention or reduction. The clamp may affix to jet pump sensing line supports and confine the individual jet pump sensing lines. The clamp may provide for further access or securing of the lines in the support through the clamp. Methods of installing the clamp may include attaching and tightening the clamp against the sensing lines.

Abstract: A nozzle apparatus of a jet pump includes a nozzle base member, and a plurality of nozzles installed to the nozzle base member and forming a plurality of narrowing portions, in which a fluid passage cross-sectional area of a driving fluid passage formed in the nozzle is reduced.

Abstract: An embodiment of the present invention provides an apparatus and system for repairing and/or maintaining a position of a first component in relation to a second component. The first and second components may be located within a reactor pressure vessel of a nuclear powerplant. The apparatus and system may attach at least one bearing plate to a horizontal surface of the first component. The apparatus and system includes structure to apply a pre-load to the first component. This may assist in maintaining the position of the first component relative to the second component.

Abstract: An embodiment of the present invention takes the form of an apparatus or system that may reduce the level of vibration experienced by an inlet riser or other similar object within a reactor pressure vessel. An embodiment of the present invention may eliminate the need for welding the riser brace to the inlet riser. An embodiment of the present invention provides at least one riser brace clamp that generally clamps the riser brace to the inlet riser. After installation, the riser brace clamp may lower the amplitude of, and/or change the frequency of, the vibration experienced by the inlet riser.

Abstract: A pressurized water reactor (PWR) includes a vertical cylindrical pressure vessel and a nuclear reactor core disposed in a lower vessel section. A hollow cylindrical central riser is disposed concentrically inside the pressure vessel. A downcomer annulus is defined between the central riser and the pressure vessel. A reactor coolant pump (RCP) includes (i) an impeller disposed above the nuclear reactor core and in fluid communication with the downcomer annulus to impel primary coolant downward through the downcomer annulus, (ii) a pump motor disposed outside of the pressure vessel, and (iii) a drive shaft operatively connecting the pump motor with the impeller. The PWR may include an internal steam generator in the downcomer annulus, with the impeller is disposed below the steam generator. The impeller may be disposed in the downcomer annulus. The RCP may further comprise a pump casing that with the impeller defines a centrifugal pump.

Abstract: A jet pump comprising: a nozzle apparatus having a header portion including, inside, a first pipe member forming a suction fluid passage for introducing suction fluid and the header portion surrounding the first pipe member, for introducing driving fluid, and a nozzle portion connected to the header portion, surrounding the first pipe member and forming an annular ejection outlet for ejecting the driving fluid; a jet pump body for mixing the driving fluid and the suction fluid sucked by the ejection of the driving fluid, and discharging the mixed fluid; and a second pipe member having one end connected to the nozzle apparatus, for introducing the driving fluid to the header portion, wherein the first pipe member is disposed through the one end inside a driving fluid passage formed in the second pipe member, and forms an opening portion of the suction fluid passage opened to the outside of the second pipe member; and the driving fluid passage is formed so that the driving fluid flowing toward the one end hi

Abstract: A boiling water nuclear reactor (BWR) multi-stage jet pump mixer assembly according to a non-limiting embodiment of the present invention may include at least one nozzle disposed above a first throat structure which is arranged within a second throat structure. The multi-stage jet pump mixer assembly is configured such that when a drive flow is discharged from the nozzle into the first throat structure, a first suction stage occurs in that a first entrained flow is drawn into the first entrainment entrance and forms a mixed flow. The mixed flow exiting the first throat structure then induces a second entrained flow into the second entrainment entrance during a second suction stage. By employing a multi-stage approach, jet pump efficiency may be improved.

Abstract: Example embodiment clamps may be used to clamp two components together, with a degree of freedom of motion between the clamped components, including both rotational and translational motion. Example embodiment clamps may clamp a BWR jet pump sensing line to a diffuser as a repair or installation of a sensing line support. Example clamps may include a ball subassembly that holds a component and allows rotation and twisting of the component within the clamp. Example clamps may further include jaws holding the ball subassembly and a biasing element that permits tightening of the clamp.

Abstract: A method for retrofitting a boiling water reactor is provided. The method includes removing a mixing chamber from a slip joint defined by a diffuser and the mixing chamber, the mixing chamber having an inner surface and a bottom edge directing flow to the diffuser such that a recirculation zone at an entrance to the slip joint creates a diverging effective path for the leakage flow entering the slip joint. The method also includes providing a new inner surface and new bottom edge, the new inner surface and the new bottom edge being reshaped to decrease the size of the recirculation zone. A jet pump is also provided.

Abstract: A method and apparatus for providing a Boiling Water Reactor (BWR) jet pump three point slip joint clamp to mitigate sleep joint leakage flow induced vibration of a BWR jet pump assembly. A collar, provided as one seamless component or in separate portions, is installed on the upper crown of a diffuser. The collar includes a lower set of fasteners and an upper set of fasteners that contact the inlet mixer and diffuser, respectively, to horizontally stabilize the inlet mixer in a fixed position inside of the diffuser. The upper fasteners may be anchored by bosses that ensure a light-weight design of the collar. An optional cantilevered seal (including a cantilevered overhang and a lip) may mitigate leakage from the slip joint interface.

Abstract: A method and apparatus for providing a Boiling Water Reactor (BWR) jet pump inlet-mixer integral slip joint clamp to constrain the inlet mixer and diffuser to mitigate inlet mixer flow induced vibration of a BWR jet pump assembly. The slip joint clamp includes horizontally projecting flanges with vertical sidewalls that protrude toward a lowest distal end of the inlet mixer. Fasteners penetrating the flanges provide a biasing load on the diffusers by being tightened to press against an upper crown on the diffuser. One or more flanges may be used. Laterally disposed gaps between the flanges may provide a clearance for guide ears of the diffuser to fit between the flanges.

Abstract: Hard stops are useable in an operating nuclear reactor to separate and bias restrainer brackets and inlet mixers. Hard stops include a lip clamp that clamps to a restrainer bracket and a wedge member that biases against the inlet mixer. The wedge member and lip clamp are engaged such that the two components can slide against one another to bias the restrainer bracket and inlet mixer. The lip clamp includes a clamp arm and an engagement member to clamp opposite sides of the restrainer bracket. Ratchet assemblies maintain selective positioning various components of the hard stops. Hard stops may be used in several different numbers, positions, and configurations in repair or modification systems. Hard stops may be installed by determining location on an outside of a restrainer bracket for the hard stop, securing the hard stop at the location, and biasing the hard stop between two components at the location.

Abstract: Slip joint clamps are installed against guide ears of diffusers at jet pump slip joints. Clamps may prevent vibration and/or movement in the slip joint while not being rigidly attached to the diffuser. Clamps include a compression flipper pressing against a guide ear of the diffuser in a substantially radial direction, a biasing member between the compression member and guide ear that presses the flipper against the guide ear, and supporting structures that hold the flipper and biasing member to the inlet mixer about the guide ear. Systems of slip joint clamps are installed against several guide ears of a single diffuser. Each clamp may radially stabilize the diffuser and inlet mixer while permitting upward relative movement of the inlet mixer. Placement and tensioning of clamps in such systems may be varied so as to prevent or reduce vibrations and/or oscillations between an inlet mixer and diffuser.

Abstract: An embodiment of the present invention takes the form of an apparatus or system that may reduce the level of vibration experienced by an inlet riser or other similar object within a reactor pressure vessel. An embodiment of the present invention may eliminate the need for welding the riser brace to the inlet riser. An embodiment of the present invention provides at least one riser brace clamp that generally clamps the riser brace to the inlet riser. After installation, the riser brace clamp may lower the amplitude of, and/or change the frequency of, the vibration experienced by the inlet riser.

Abstract: A support clamp assembly for mechanically securing a thermal sleeve to an elbow conduit in a jet pump of a nuclear reactor vessel, the support clamp assembly including: a tension shaft having a first end extendable through an opening in a sidewall of the elbow conduit and an opposite end with a head; a cruciform assembly having a base with an opening to receive the tension shaft and to abut the head of the shaft, wherein the cruciform assembly seats in the thermal sleeve; a boss slidable over the first end of the tension shaft and having a curved surface seating an outside surface of the elbow conduit, and a coupling device engaging the first end of the tension shaft and abutting the boss, wherein the coupling device places the tension shaft under tension to secure the cruciform assembly to the thermal sleeve and the boss to the elbow conduit.

Abstract: A method and apparatus for a Boiling Water Reactor (BWR) jet pump inlet mixer support that provides rigid support for inlet mixers. The inlet mixer support attaches to a conventional BWR jet pump assembly to pull the inlet mixer away from the centerline of a riser pipe or maintain the existing inlet mixer position. The inlet mixer support may provide redundant support that may otherwise be provided by set screws of a conventional restrainer assembly. The inlet mixer support may, alternatively, be used in lieu of conventional set screws. The inlet mixer support may also counter-act additional side loading that may be applied to inlet mixers to stabilize inlet mixer movement and vibration when the BWR jet pump assembly is in operation. Optionally, the inlet mixer support may also prevent removal of existing restrainer bracket set screws.

Abstract: A method and apparatus for physically restraining an inlet mixer of a boiling water reactor (BWR) jet pump assembly. An inlet mixer clamp assembly is attached to the top of a transition piece of the BWR jet pump assembly, to provides a downward clamping force on the top of the inlet mixer. The clamping force restrains the inlet mixer from experiencing vibration and mitigates leakage between the inlet mixer and the transition piece sealing surfaces of the jet pump assembly. The clamping force also restrains the inlet mixer from undesirable rotation, especially during operation of the jet pump assembly. The inlet mixer clamp assembly may be used as an alternative to conventional jet pump beam assemblies. Alternatively, the inlet mixer clamp assembly may be used as a redundant physical restraint in addition to the conventional jet pump beam assemblies.

Abstract: The present invention has an object to provide a jet pump, which can restrain self-excited vibration in a connection portion between an inlet mixer pipe and a diffuser pipe without inhibiting a structural deformation due to thermal expansion and the like. The jet pump includes: a slip joint structure connecting the inlet mixer pipe and the diffuser pipe to each other by inserting the inlet mixer pipe into an upper end opening of the diffuser pipe with a clearance left therebetween; and a self vibration damping structure configured such that when the clearance defined by an outer pipe wall of the inlet mixer pipe and an inner pipe wall of the diffuser pipe is widening or narrowing due to vibration of the inlet mixer pipe or the diffuser pipe, a flow path resistance inside a clearance flow path for pumped coolant water defined by the clearance is not smaller than a fluid inertia force all over the clearance flow path.

Abstract: Example embodiment damping devices may include a housing capturing a piston. The housing may be filled and/or able to be filled with a damping fluid compatible with the nuclear reactor coolant, so that a leak from the housing or coolant passing into the housing does not damage the reactor or example embodiment devices. Example embodiments may further include one or more springs that provide an elastic force opposing movement between the piston and housing. A shaft of the piston and an end of the housing may be connected to two nuclear reactor components with relative motion or vibration to be damped. Example methods may use example embodiment damping devices to reduce and/or prevent relative motion and vibration among components of a nuclear reactor.

Abstract: A boiling water nuclear reactor (BWR) multi-stage jet pump mixer assembly according to a non-limiting embodiment of the present invention may include at least one nozzle disposed above a first throat structure which is arranged within a second throat structure. The multi-stage jet pump mixer assembly is configured such that when a drive flow is discharged from the nozzle into the first throat structure, a first suction stage occurs in that a first entrained flow is drawn into the first entrainment entrance and forms a mixed flow. The mixed flow exiting the first throat structure then induces a second entrained flow into the second entrainment entrance during a second suction stage. By employing a multi-stage approach, jet pump efficiency may be improved.

Abstract: A support clamp assembly for mechanically securing a thermal sleeve to an elbow conduit in a jet pump of a nuclear reactor vessel, the support clamp assembly including: a tension shaft having a first end extendable through an opening in a sidewall of the elbow conduit and an opposite end with a head; a cruciform assembly having a base with an opening to receive the tension shaft and to abut the head of the shaft, wherein the cruciform assembly seats in the thermal sleeve; a boss slidable over the first end of the tension shaft and having a curved surface seating an outside surface of the elbow conduit, and a coupling device engaging the first end of the tension shaft and abutting the boss, wherein the coupling device places the tension shaft under tension to secure the cruciform assembly to the thermal sleeve and the boss to the elbow conduit.

Abstract: An auxiliary wedge positioning apparatus/assembly 100 for use in a nuclear reactor pressure vessel 12 having riser piping 44 and 144 and a jet pump assembly 46 and 120, the apparatus 100 having a combination slide wedge 105 and spring 103 mounted on a restraint bracket body 102 having a transverse rail 110 with end gull-wing hooked protrusions 111 with sections 150, 152, 156 and wing stability attachment 155, the slide wedge used for placement between the riser piping 44 and 144 and jet pump assembly 46 and 120 to control vibrations during operation of the reactor vessel 12.

Abstract: A jet pump beam is made of improved heat-treated precipitation-hardened nickel base alloy excellent in anti-stress corrosion cracking properties and high-temperature strength, and having high ductility and a high elastic modulus. A jet pump beam 27 made of improved heat-treated nickel base alloy is produced by preparing a precipitation-strengthened nickel base alloy material having a component composition containing by mass %, Ni: 50.0% to 55.0%, Cr: 17.0% to 21.0%, Nb+Ta: 4.75% to 5.50%, Mo: 2.8% to 3.3%, Ti: 0.65% to 1.15%, Al: 0.2% to 0.8%, C: 0.08% or less, Mn: 0.35% or less, Si: 0.35% or less, S: 0.015% or less, P: 0.03% or less, Cu: 0.30% or less, B: 0.006% or less, and Co: 1.0% or less, and Fe and inevitable impurities constituting a remaining part, subjecting the nickel base alloy material to solution heat treatment at a temperature of 1010° C. to 1090° C., and subjecting the nickel base alloy material to age-hardening heat treatment at a temperature of 694° C. to 714° C.

Abstract: Disclosed is a method for reducing electrostatic deposition of charged particles on wetted surfaces that are exposed, periodically or substantially continuously to high velocity fluid flow within a coolant flow path in a nuclear reactor. The method includes depositing a first or base dielectric layer and a second or outer dielectric layer on a conductive surface that forms a portion of a high velocity flow path. The first dielectric layer material is selected to provide improved adhesion and insulation to the conductive surface and the second dielectric layer material is selected to provide suitable adhesion to the first dielectric layer and improved corrosion and/or mechanical resistance in the anticipated operating environment.

Abstract: An embodiment of the present invention provides an apparatus and system for repairing and/or maintaining a position of a first component in relation to a second component. The first and second components may be located within a reactor pressure vessel of a nuclear powerplant. The apparatus and system may attach at least one bearing plate to a horizontal surface of the first component. The apparatus and system includes structure to apply a pre-load to the first component. This may assist in maintaining the position of the first component relative to the second component.