Abstract: A method and apparatus for securely fastening a pipe collar or a bracket to a riser pipe of a boiling water reactor (BWR) jet pump assembly. A pipe plug assembly includes an angled pipe plug that acts as a wedge to expand a bushing assembly as the pipe plug is drawn into the overall pipe plug assembly. Expansion of the bushing assembly allows a tight tolerance to exist between an outer diameter of the pipe plug and an inner diameter of the collar/bracket and riser pipe. Expansion of the bushing assembly allows a straight hole to be match drilled into the collar/bracket and riser pipe, thereby avoiding a more complicated tapered hole to be drilled into the collar/bracket and riser pipe. An ensuing tight fit between the pipe plug assembly, the collar/bracket and the riser pipe mitigates vibration of components and minimizes leakage to acceptable levels for use in the flooded environment of the annulus region where the jet pump assembly exists in the BWR.

Abstract: A method and apparatus for repairing and/or reinforcing a Boiling Water Reactor (BWR) jet pump riser pipe. The repair includes attaching two collars to the riser pipe using match drilling to drill holes through the collars and the riser pipe and plugging the holes with expandable plugs. Support columns are attached to the collars. Brace supports are slideably attached to the support columns. Gaps between each brace support and its respective collar are then narrowed as ratchet bolts may apply a force that pulls downward on an upper collar and pulls upward on a lower collar, thereby exerting a compression force on the riser pipe. A clamp assembly may also be located between the two collars that applies a hoop force on the riser pipe.

Abstract: A preventive maintenance/repair device 10 of the present invention includes: a device body 11, and holding mechanisms 13a and 13b connected to the device body 11, the holding mechanisms 13a and 13b being configured to hold the device body 11 on an outer circumferential surface of a cylindrical structure 19. Further, the device body 11 is equipped with a traveling and driving part configured to be circumferentially movable along the outer circumferential surface of the cylindrical structure 19. Furthermore, each of the holding mechanisms 13a and 13b is equipped with a maintenance/repair mechanism 16 configured to maintain and repair the cylindrical structure 19.

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 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 pressurized water reactor (PWR) includes a pressure vessel containing a nuclear core comprising a fissile material immersed in primary coolant water. A reactor coolant pump (RCP) is configured to pump primary coolant water in the pressure vessel. The RCP includes a hydraulically driven turbo pump disposed in the pressure vessel. The turbo pump includes an impeller performing pumping of primary coolant water in the pressure vessel, and a hydraulically driven turbine mechanically coupled with the impeller to drive the impeller. The RCP may further include a hydraulic pump configured pump primary coolant water to generate hydraulic working fluid that drives the hydraulically driven turbine. The hydraulic pump may be a canned pump having a casing defining a portion of the pressure boundary of the pressure vessel. The casing includes electrical feedthroughs delivering electrical power to the hydraulic pump.

Abstract: A nuclear reactor includes a nuclear core comprising a fissile material, and a pressure vessel containing the nuclear core immersed in primary coolant water. Turbo pumps disposed in the pressure vessel provide active circulation of primary coolant water in the pressure vessel. Each turbo pump includes a turbine driving an impeller. A manifold plenum chamber is disposed in the pressure vessel, and is in fluid communication with inlets of the turbines of the turbo pumps. An electrically driven pump operatively connected with the manifold plenum chamber to pressurize the manifold plenum chamber with primary coolant water. The turbo pumps may be disposed in openings passing through the manifold plenum chamber. The pressure vessel may be vertically oriented and cylindrical, with a cylindrical riser oriented coaxially inside, and the manifold plenum chamber may be annular and disposed in a downcomer annulus defined between the cylindrical riser and the cylindrical pressure vessel.

Abstract: An integral pressurized water reactor (PWR) includes a cylindrical pressure vessel, a cylindrical central riser disposed coaxially inside the cylindrical pressure vessel wherein a downcomer annulus is defined between the cylindrical central riser and the cylindrical pressure vessel, a nuclear core comprising a fissile material, and a steam generator disposed in the downcomer annulus. A reactor coolant pump (RCP) includes a jet pump disposed in the downcomer annulus above or below the steam generator, and a hydraulic pump configured to pump primary coolant into a nozzle of the jet pump. The hydraulic pump includes an electric motor mounted externally on the pressure vessel.

Abstract: A reactor coolant pump (RCP) generates primary coolant flow in a nuclear reactor. The RCP includes a flow amplification device, such as a turbo pump, disposed in the pressure vessel of the nuclear reactor, and an electrically driven pump (e.g. a centrifugal pump). The inlet of the electrically driven pump receives primary coolant water from the pressure vessel and the outlet discharges into the driving inlet of the flow amplification device (e.g. into the turbine of a turbo pump) such that the centrifugal pump drives the flow amplification device to pump primary coolant water. A divider is disposed in the pressure vessel and separates the pumping inlet of the flow amplification device from the pumping outlet of the flow amplification device. The electrically driven pump may include hydraulic drive shaft bearings and starting mechanical drive shaft bearings that disengage at operating speed due to axial shift of the drive shaft.

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: Example embodiments are directed to jet pump inspection apparatuses including an encoded probe driver coupled to a guide funnel. In an example embodiment, the encoded probe driver and the guide funnel are located on the body of the apparatus in order to decrease the time required for inspection, thereby limiting exposure to personnel of radioactive contamination.

Abstract: A method and apparatus for a boiling water reactor (BWR) jet pump inlet mixer compliant stop. The inlet mixer compliant stop may be installed in a pocket area between a riser pipe and an inlet mixer of a BWR jet pump assembly. The inlet mixer compliant stop includes a main body and a foot that are separated via the tightening of one or more jacking bolts used to connect the main body and the foot. A cold spring attached to the main body provides a lateral force that is imparted on the inlet mixer, to force the inlet mixer away from a centerline of the riser pipe. A precise lateral force may be imparted on the inlet mixer by gauging a width of a gap between opposing bosses on a front face of the main body and a distal end of the cold spring. The inlet mixer compliant stop imparts a greater lateral force on the inlet mixer as the jacking bolts are tightened, further separating the main body from the foot, as the gap between the opposing bosses is reduced.

Abstract: A method and apparatus for repairing and/or reinforcing a Boiling Water Reactor (BWR) jet pump riser pipe. The repair includes attaching two collars to the riser pipe using match drilling to drill holes through the collars and the riser pipe and plugging the holes with expandable plugs. Support columns are attached to the collars. Brace supports are slideably attached to the support columns. Gaps between each brace support and its respective collar are then narrowed as ratchet bolts may apply a force that pulls downward on an upper collar and pulls upward on a lower collar, thereby exerting a compression force on the riser pipe. A clamp assembly may also be located between the two collars that applies a hoop force on the riser pipe.

Abstract: A method and apparatus for securely fastening a pipe collar or a bracket to a riser pipe of a boiling water reactor (BWR) jet pump assembly. A pipe plug assembly includes an angled pipe plug that acts as a wedge to expand a bushing assembly as the pipe plug is drawn into the overall pipe plug assembly. Expansion of the bushing assembly allows a tight tolerance to exist between an outer diameter of the pipe plug and an inner diameter of the collar/bracket and riser pipe. Expansion of the bushing assembly allows a straight hole to be match drilled into the collar/bracket and riser pipe, thereby avoiding a more complicated tapered hole to be drilled into the collar/bracket and riser pipe. An ensuing tight fit between the pipe plug assembly, the collar/bracket and the riser pipe mitigates vibration of components and minimizes leakage to acceptable levels for use in the flooded environment of the annulus region where the jet pump assembly exists in the BWR.

Abstract: Systems and method for tensioning jet pump beam bolts in a nuclear reactor are disclosed. The nuclear reactor may include at least one jet pump with each jet pump having a jet pump beam and a jet pump beam bolt. The system may include an actuating apparatus and a tensioning apparatus. The actuating apparatus may include a socket member for engaging the jet pump beam bolts, a sleeve member for engaging a handling pole, and an actuator hex positioned between the socket member and the sleeve member. The tensioning apparatus may include a base block having an opening for accommodating the jet pump beam bolt, a top plate having an opening for accommodating the actuator hex, and a hydraulic actuator for providing tension to the jet pump beam bolt in accordance to measurements of the actuating apparatus.

Abstract: A clamp assembly connects a diffuser adapter or lower ring to a diffuser tail pipe of a jet pump diffuser in a boiling water nuclear reactor. The clamp assembly includes at least two clamp segments shaped generally corresponding to an exterior circumference of the diffuser, a swivel link affixed at each end of each of the clamp segments, and at least two connecting bands pivotably secured to the swivel links between the ends of the clamp segments. The clamp segments each includes a locking assembly engageable with the diffuser adapter or lower ring and the diffuser tail pipe. The clamp assembly structurally replaces/repairs the weld joining the diffuser adapter or lower ring and the diffuser tail pipe.

Abstract: An apparatus and method are provided which are designed to structurally replace welds that attach a riser brace assembly to a jet pump riser pipe. The riser brace assembly may include an upper clamp assembly, a lower clamp assembly, and a plurality of mechanical fasteners to provide clamping forces to the upper clamp assembly and the lower clamp assembly. The upper clamp assembly and the lower clamp assembly sandwich a riser brace support, wherein the riser brace support is provided with at least one through-hole to accommodate the plurality of mechanical fasteners.

Abstract: Object of this invention is to provide an axial torsional vibration measurement device of the reactor internal pump capable of measuring the axial torsional vibration easily. The vibration detector 2 that detects vibration in the radial direction, and the sound detector 3 that detects vibration in the circumferential direction are fitted on cylindrical motor casing 6, which contains the motor of a reactor internal pump. The dimension of both signals of a vibration waveform signal detected by the vibration detector 2, and a sound waveform signal detected by the sound detector 3 are matched in vibration calculating device 15, to thereby obtain an axial torsion vibration of a motor from the difference of both signals.

Abstract: Object of this invention is to provide an axial torsional vibration measurement device of the reactor internal pump capable of measuring the axial torsional vibration easily. The vibration detector 2 that detects vibration in the radial direction, and the sound detector 3 that detects vibration in the circumferential direction are fitted on cylindrical motor casing 6, which contains the motor of a reactor internal pump. The dimension of both signals of a vibration waveform signal detected by the vibration detector 2, and a sound waveform signal detected by the sound detector 3 are matched in vibration calculating device 15, to thereby obtain an axial torsion vibration of a motor from the difference of both signals.

Abstract: The invention relates to a method of repairing the labyrinth seal of a diffuser in a primary pump, the diffuser being of the type comprising a peripheral skirt and a circular end wall having an orifice provided with the labyrinth seal. The method consists in making a bore in the circular end wall having a diameter greater than that of the orifice, in reducing the thickness of the remaining portion of the end wall, in forming a chamfer on the edge of the bore, in positioning a replacement part in said bore, the replacement part including a central orifice and a chamfer on its own peripheral edge, in making a bead of welding between the chamfers, and in making a new labyrinth seal in the central orifice of the replacement part.

Abstract: Methods for cutting a labyrinth seal in a nuclear reactor jet pump assembly are described. In one embodiment, the method includes removing an irradiated jet pump inlet mixer from the jet pump assembly, positioning the jet pump inlet mixer underwater, and cutting at least one circumferential groove in an inlet mixer outside surface.

Abstract: A reactor pressure vessel (RPV) for a nuclear reactor that permits measurement of the flow through each reactor internal pump (RIP) is described. The reactor pressure vessel also includes at least one reactor internal pump that includes an impeller and a pump diffuser. At least two seal rings extend circumferentially around an outer surface of the diffuser housing outer wall and are located in circumferential grooves in the housing outer wall. At least one lateral bore extends through the housing outer wall into a diffuser housing longitudinal flow passage. Each lateral bore is located in an area between two adjacent seal rings, with each inter-seal ring area containing one lateral bore. At least one pressure tap bore extends from the outer surface of the RPV bottom head petal, through the pump deck to an inner surface of a pump deck opening. Each pressure tap bore is aligned with an area in the RIP containing a corresponding lateral bore.

Abstract: An auxiliary wedge apparatus configured to couple to the restrainer bracket of a jet pump assembly is described. In one embodiment, the auxiliary wedge apparatus includes a support block configured to couple to the restrainer bracket, and a wedge configured to slidingly couple to a wedge channel in the support block, and to engage the inlet mixer to restore a tight rigid fit-up of the jet pump components. The support block includes a wedge channel having tongues depending from the parallel sides of the channel and a hook shaped portion configured to receive the restrainer bracket. The support block also includes a lock screw to couple the support block to the restrainer bracket. The wedge includes grooves in the parallel sides of the wedge configured to slidingly engage the tongues extending in the wedge channel.

Abstract: A jet pump assembly for recirculating coolant through a recirculation loop of a boiling water reactor vessel, the jet pump assembly comprises a jet pump in operative association with the recirculation loop for forcing the coolant through the recirculation loop. A beam is positioned adjacent and in operative association with the jet pump for assisting in maintaining the positional relationship of the jet pump. A bolt is inserted in the beam for resisting the hydraulic forces generated in the jet pump, and an insert is disposed in said beam for receiving and surrounding the bolt which, in turn, reduces stress on the beam.

Abstract: A system of extracting fluid samples, either liquid or gas, from the interior of a nuclear reactor containment utilizes a jet pump. To extract the sample fluid, a nonradioactive motive fluid is forced through the inlet and discharge ports of a jet pump located outside the containment, creating a suction that draws the sample fluid from the containment through a sample conduit connected to the pump suction port. The mixture of motive fluid and sample fluid is discharged through a return conduit to the interior of the containment. The jet pump and means for removing a portion of the sample fluid from the sample conduit can be located in a shielded sample grab station located next to the containment. A non-nuclear grade active pump can be located outside the grab sampling station and the containment to pump the nonradioactive motive fluid through the jet pump.

Abstract: A ventilating system for an enclosure in a nuclear power plant is provided. The enclosure houses an emergency feedwater pump and its driver steam turbine. An eductor mounted in the enclosure is supplied with steam exhausting from the driver steam turbine. The steam jet formed by the eductor draw hot air out of the enclosure, thereby preventing the excessive build-up of heat in the enclousre. An air inlet formed in another wall of the enclosure supplies the enclosure with cool ambient air. The eductor and air inlet are situated to ensure the incoming air flows over the pump, thereby cooling it. A duct transports the steam/air mixture discharged by the eductor to the atmosphere.

Abstract: The multistage injection of water into the pressure vessel of a nuclear reactor including the steam-driven injection of water using steam generated by the reactor, the stages of injection subject to the cooling of water heated by the steam, whereby the pressure level of the water injected is boosted in stages.

Abstract: The system removes heat from a vessel containing the source of heat, utilizing hot water heated by energy released in the vessel as the power supply. The hot water passes through a subcooler and a convergent-divergent nozzle of a flash jet pump where it is accelerated to supersonic velocity. Cold water is drawn into the flash jet pump by the supersonic flow generated and mixes with the water flashed into steam. The mixture is condensed and forced under pressure through connecting pipes into the pressure vessel. A second flash jet pump is utilized to initially fill the vessel with coolant water.