Abstract: The present invention provides passive safety equipment, comprising: a cooling part formed to cool a first fluid, which is emitted from a reactor coolant system or a steam generator, and a second fluid in a housing; and a circulation induction sprayer which is formed to spray the first fluid emitted from the reactor coolant system or the steam generator into the cooling part, has at least part thereof open to the inside of the housing such that the second fluid flows thereinto according to a drop in pressure caused by the spraying of the first fluid, and sprays the second fluid with the inflown first fluid.

Abstract: Flow induced vibration (FIV) at the slip joint between a nuclear reactor jet pump mixer and diffuser is suppressed without installing additional parts or altering the jet pump construction. The disclosed method determines a relationship between reactor operating conditions that trigger FIV and the magnitude of a mixer/diffuser transverse contact load. A mathematical analysis on a representative jet pump configuration determines the quantitative relationship between mixer/diffuser cold positions and their positions when the reactor is operating. Thus, a prediction can be made as to whether an installed jet pump will experience FIV, and the mixer and diffuser can be positioned by a mixer adjustment tool when the reactor is cold to provide the necessary operational transverse contact load. Alternatively, a contact load measuring tool directly measures the magnitude and direction of the cold mixer/diffuser transverse contact load to determine if FIV will be suppressed when the reactor is operating.

Abstract: An embodiment of the present invention takes the form of a system that may reduce the level of flow-induced vibration (FIV) experienced by a jet pump assembly or other similar object within a pressure vessel. Essentially, an embodiment of the present invention may reduce the slip-joint leakage, which may be a cause of the FIVs, by adding a flow-limiting component to an outlet of the slip joint. This component may take the form of a collar, channel, and/or other component that may be connectable to a component of the jet pump assembly. After installation, an embodiment of the present invention may lower the amplitude of, and/or change the frequency of, the FIVs experienced by the jet pump assembly.

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: 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: 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: 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: Example embodiments relate to a method and apparatus 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 may include 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 to attain the apparatus. 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: 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: 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: A jet pump including a riser as a coolant supply tube, an inlet mixer forming a turn-around path for the coolant, a diffuser, and a jet pump beam provided with a bolt fixing device is disclosed. The bolt fixing device includes: a head bolt of a jet pump beam for pushing and supporting the inlet mixer from an upper side of the riser, the head bolt being provided with a polygonal head portion; a lock cap provided on the polygonal head portion of the head bolt; a body housing disposed on an upper surface of the jet pump beam and adapted to accommodate the lock pin; a plurality of tapered external teeth formed on an outer peripheral side surface of the lock cap; and a plurality of internal tooth-shaped grooves formed to the body housing to fix the head bolt of the jet pump beam.

Abstract: A jet pump assembly according to an example embodiment of the present invention includes an inlet body arranged in proximity with a throat structure so as to provide an entrainment entrance between a discharge end of the inlet body and the throat structure. A drive flow of a motive fluid is supplied at a first velocity to the inlet body and is discharged through at least one nozzle at a higher second velocity, thereby creating a pressure drop in the throat structure. The pressure drop facilitates a first entrained flow of suction fluid into the entrainment entrance and a second entrained flow of suction fluid through at least one channel passing through the inlet body. The at least one channel is configured such that the second entrained flow is isolated from the drive flow while passing through the inlet body.

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 vertical spring wedge restores a tight fitup against an adjacent structure, such as between an inlet mixer and an adjacent restrainer bracket in a boiling water nuclear reactor jet pump. The vertical spring wedge includes a U-shaped bracket including a pair of guiding portions and a pair of bracket holes. A pair of wedge assemblies are coupled with the bracket, each of the wedge assemblies including a wedge segment attached to a spring-loaded guide rod. The guide rods are displaceable in the bracket holes between a retracted position and an extended position. The wedge segments engage the guiding portions, and a combination of the bracket and wedge assemblies have a first width when the guide rods are in the retracted position and have a second width wider than the first width when the guide rods are in the extended position.

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: A composite sparger for use in elevated temperature and corrosive environments. The composite sparger is formed from a thermally conductive non-combustible metal substrate. The surfaces of the conductive non-combustible metal exposed to the reactor environment are protected with a corrosion resistant layer. The corrosion resistant layer protects the substrate material from the corrosive environment of the reactor vessel and the substrate material conducts heat away from the corrosion resistant layer to prevent combustion of the corrosion resistant layer. The substrate material and corrosion resistant material may be selected so as to provide for sufficient thermal conduction to prevent combustion of the corrosion resistant material.

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 steam injector is characteristic in its high pressure and improved start-up. It uses an axial drain (10) positioned in the centre of the neck (5) downstream from the mixing chamber (4) and inserted in the diffuser (7) for the purpose of narrowing the section of the neck (5) and evacuating a large part of the steam which has not been condensed. The axial drain (10) may be mounted so that it is axially mobile. Application to the water supply for steam generators in pressurized water nuclear reactors.

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: A remotely installable piping support device includes a pair of mating tapered wedge segments extending from lever arms connected with a spiral wound spring. The spring is machined integrally with the left lever arm and has a projecting center square drive hub with an internal mounting thread. The right lever arm has an internal square drive which mates with the drive hub. A bolt engages the drive hub and secures the lever arms together. The spring preload on the wedge acting across the shallow angled wedge surfaces maintains rigid contact between jet pump components and takes up the clearance from wear during operation.

Abstract: A seal apparatus for a jet pump slip joint in a boiling water nuclear reactor pressure vessel, in an exemplary embodiment, includes a split seal ring and a segmented diaphragm spring engaging the split seal ring at an inner circumference of the diaphragm spring. The diaphragm spring includes a plurality of latch assemblies spaced circumferentially around an outer circumference. A plurality of slots, spaced circumferentially around the inner circumference, extend from the inner circumference to the support portion. Each latch assembly includes a latch bolt extending through and threadendly engaging a corresponding latch bolt opening in the diaphragm spring. Each latch bolt includes a head and a plurality of ratchet teeth spaced around the periphery of the latch bolt head. A locking spring is positioned to engage the ratchet teeth of the latch bolt head. The latch assembly further includes a latch arm coupled to the latch bolt. The latch arm includes a slot sized to receive a diffuser guide ear.

Abstract: A jet pump beam bolt locking assembly includes a locking sleeve having a plurality of ratchet teeth extending around the periphery of a base portion, and a lock plate having a beam bolt opening, and an integral beam spring arm having a plurality of ratchet teeth extending from at least a portion of a side of the spring arm. The spring arm ratchet teeth are sized to mesh with the locking sleeve ratchet teeth. The lock plate also includes a lip extending at least partially around the beam bolt opening which captures the locking sleeve. The spring arm is movable between a first position where a lock plate detent is positioned in a spring arm notch which permits engagement of the ratchet teeth, and a second position where the side of the spring arm is in contact with the detent which disengages the ratchet teeth to permit loosening of the beam bolt.

Abstract: A remotely installable piping support device includes a pair of mating tapered wedge segments extending from lever arms connected with a spiral wound spring. The spring is machined integrally with the left lever arm and has a projecting center square drive hub with an internal mounting thread. The right lever arm has an internal square drive which mates with the drive hub. A bolt engages the drive hub and secures the lever arms together. The spring preload on the wedge acting across the shallow angled wedge surfaces maintains rigid contact between jet pump components and takes up the clearance from wear during operation.

Abstract: A locking device for use in restraining a jet pump downcomer of a nuclear reactor, including an upper jaw; a lower jaw placed in an opposing position below the upper jaw; and a tightening screw movably supporting the upper jaw and the lower jaw. When installed on a jet pump downcomer, the complete assembly includes a restraining ring; a downcomer carried by the restraining ring; a wedge supported by the restraining ring and the downcomer; and a guide bolt extending in an axial direction in relation to the downcomer such that the wedge is movably supported by the guide bolt. The wedge is interposed between the upper jaw and the lower jaw, and one end of the upper jaw and a corresponding end of the lower jaw are moveably supported by the guide bolt. The upper jaw and lower jaw are supported at their respective opposite ends by the tightening screw.

Abstract: A locking device for use in restraining a jet pump downcomer of a nuclear reactor, including an upper jaw; a lower jaw placed in an opposing position below the upper jaw; and a tightening screw movably supporting the upper jaw and the lower jaw. When installed on a jet pump downcomer, the complete assembly includes a restraining ring; a downcomer carried by the restraining ring; a wedge supported by the restraining ring and the downcomer; and a guide bolt extending in an axial direction in relation to the downcomer such that the wedge is movably supported by the guide bolt. The wedge is interposed between the upper jaw and the lower jaw, and one end of the upper jaw and a corresponding end of the lower jaw are moveably supported by the guide bolt. The upper jaw and lower jaw are supported at their respective opposite ends by the tightening screw.

Abstract: Apparatus for supporting the lower elbow assembly of a jet pump in a reactor pressure vessel (RPV) of a nuclear reactor are described. The clamp apparatus includes a lower clamp element and an upper clamp element. The upper and lower elements are configured to be positioned at the interface between the thermal sleeve and the jet pump riser elbow. The upper and lower elements include extended ridges that are configured to fit in circumferential grooves precisely machined into the sleeve-elbow assembly on opposing sides of the interface.

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 depressurization system (1) for pressurized steam operated plant employing injection of cold water contained in a superelevated tank (5), said injection being triggered rapidly and in a manner independent of the magnitude of the damage and of the presence of incondensible gases, by means of a natural circulation of steam in a closed loop of pipes (19, 20, 21, 22) around said plant (2, 3, 4), caused by the condensation of steam in a condenser (10), placed on said pipes, during the occurence of an accident, comprises a first siphon-type hydraulic shutoff (32), on said pipe loop (19, 20, 21, 22) and arranged close to the inlet collector (14) of said condenser (10), a second siphon-type hydraulic shutoff (29), on the cold water delivery pipe (26) and placed close to the pressurized steam operated plant (2, 3, 4), said second siphon-type hydraulic shutoff (29) being below said first siphon-type hydraulic shutoff (32).

Abstract: The injector (B) designed specifically to supply a steam generator (G) with water at high pressure when necessary, is supplied by steam that may originate from the generator itself, and by pressurized water from an ejector (C) supplied during the start up phase by a water circuit (D) pressurized by steam, and during the steady state phase, by an extraction circuit (R) connected on the downstream side of the injector. This device entrains water originating from a tank at low pressure (73) into injector (B), to pressurize it at a pressure exceeding the steam pressure.Application to safety devices in nuclear power stations.

Abstract: Internal condenser system for discharging vapor from a circuit into a tank or pool to reduce pressure in said circuit.The internal condensation conduit (47) comprises a diaphragm (52) just upstream of a cold liquid feed orifice (55); the jet of vapor passing through orifice (53) of the diaphragm creates a zone of significantly negative pressure around this jet and downstream of the diaphragm causing cold liquid to be sucked up. This causes the vapor to condense in the mixing chamber (56).One possible application relates to primary circuits of a nuclear reactor.

Abstract: A depressurizing system (1) for depressurizing plants, operating with pressurized steam and including a steam head (16), by injection of cold water under gravity from a reservoir (2) located at a higher level than the pressurized plant and connected thereto by a delivery duct (24) which forms a syphon (24a, 24b, 24c) and which is connected to the narrow section (10) of an ejector (6) into which steam flows in the event of an incident, the steam being drawn from a condenser (7) located downstream of the ejector (6), causing a drop in pressure which draws cold water from the tank (2) through the syphon which is thus overcome, enabling cold water to be injected into the pressurized plant.

Abstract: A reactor core coolant flow rate control system for a BWR type nuclear power plant in which electric power is generated by a turbine-driven generator driven by a steam turbine rotating under the work of a main steam generated from a cooling water recirculated through a boiling water reactor includes an internal pump driving unit comprised of an electric motor driven by an electric power generated by the turbine-driven generator, a fluid coupling for transmitting an output torque of the electric motor and a variable-frequency generator whose rotation number is changed in accordance with the torque transmitted by way of the fluid coupling, a fluid coupling control signal generating unit for generating a fluid coupling control signal for the fluid coupling in response to at least one of deviation in a load and a rotation speed of the turbine-driven generator and deviation in a rotation speed of the internal pumps, and a plurality of internal pumps for recirculating the cooling water.

Abstract: A jet condenser injects steam from a steam generator into a mixing tube, where it combines with coolant water from a heat exchanger. The steam completely condenses Upon mixing with the water because the ratio of the mass flow rate of water to that of steam is relatively high at any given combination of temperatures and pressures. The mixture of coolant water and condensate then enters a divergent tube. This action enhances dynamic natural convection in the condenser loop, which provides the forces that move the water through the loop. A small portion of the water is returned to the steam generator; the remainder is diverted to the heat exchanger. The mass flow of the steam in the jet condenser is equal to that of the condensate returned to the steam generator, thereby maintaining a constant coolant water inventory. During an accident, radioactive fission products would be retained within the closed jet condenser loop.

Abstract: A nozzle includes a barrel being integral with a vessel and includes a first bore. A safe end is joined at one end to the barrel by a first weld and at an opposite end to an inlet pipe at a second weld. A first thermal sleeve is disposed inside the first bore and has one end disposed in an interference fit with a second bore of the safe end. In order to repair the nozzle for reducing leakage at the interference fit between the first and second bores, a method includes removing a portion of the inlet pipe and the weld at the safe end and installing a replacement extension therefor. The extension includes a tubular body having a first fork at one end joined to the safe end by a replacement weld, and having a distal end joined to the inlet pipe at a third weld. A second fork is disposed concentrically inside the body and is integrally joined at one end with an intermediate portion of the body, and includes a distal end extending toward the safe end.

Abstract: A steam injector system comprises a plurality of steam injectors each being provided with with a check valve adapted for water supply, a check valve adapted for steam supply, a check valve adapted for overflow and a check valve adapted for discharge and the respective water check valves, steam check valves, overflow check valves and discharge check valves are connected. In another aspect, a steam injector system comprises a plurality of first to last stage steam injectors arranged in series with each other, the last stage steam injector being provided with a relief valve disposed at a last stage overflow drain port, and a pressure pulsation absorbing device is disposed at least between the last stage overflow drain valve and the relief valve.

Abstract: A BWR coolant recirculation system includes a pump deck disposed in a downcomer and fixedly joined to a reactor pressure vessel and reactor core shroud. A plurality of circumferentially spaced reactor internal pumps (RIPs) are joined to the deck and operable in a pumping mode for pumping downwardly a reactor coolant from the downcomer and into a core inlet. In a pump inoperable mode, a portion of the coolant bypasses the RIPs for allowing increased natural recirculation of the coolant from the downcomer and into the core inlet.

Abstract: A recirculation system is disclosed for driving reactor coolant water contained in an annular downcomer defined between a reactor vessel and a reactor core spaced radially inwardly therefrom. The system includes a plurality of circumferentially spaced pumps disposed in the downcomer, each pump including an inlet for receiving coolant water from the downcomer as pump inlet flow, and an outlet for discharging the pressurized water. The recirculation system firstly increases the pressure of the pump inlet flow at the pump inlet before being sucked into the pump for being further pressurized by the 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: A recirculation system for a boiling water reactor includes a plurality of circumferentially spaced impeller-driven reactor internal pumps disposed in a downcomer for pumping a first portion of reactor coolant, and a plurality of circumferentially spaced fluid-driven jet pumps disposed in the downcomer for pumping a remaining portion of the coolant in the downcomer. In an exemplary embodiment, the jet pumps are driven by a portion of feedwater provided to the reactor.

Abstract: An intermediate heat transport system is disclosed for providing steam generation from the secondary nonradioactive liquid sodium heat extraction loop from a sodium cooled nuclear reactor. The transport system includes a unitary module combining the steam generating heat exchanger, the pump for the circulation of the liquid sodium coolant, and the surge volume required for differential expansion between the sodium and the vessels that contain the sodium. Two concentric cylindrical and vertically standing vessels are provided for containing the liquid sodium; one vessel is outer and larger; the other inner vessel is of a double wall construction and open on its lower end hung from the top of the longer vessel. The outer and larger cylindrical vessel has four feedwater inlet plenums (typical number) at the bottom and four steam outlet plenums at the top. Tube sheets terminate each plenum to a tube bundle extending between the inlet and outlet plenums.

Abstract: The invention relates to an ejector to be placed in rooms which are inaccible to human beings. It comprises a casing with a diffuser bore, a head chamber, and a space for a working fluid including a lateral working fluid connection. The working fluid nozzle comprises a working fluid chamber which is connected through bores with the working fluid space and, inside the casing, it seals the head chamber from the working fluid space. The nozzle of the working fluid chamber opens into the head chamber and faces the diffuser bore. The invention is characterized in that the ends of the casing and of the working fluid nozzle each are embodied as a radial flange which flanges are held together by bolts adapted to be operated by a manipulator. At the end of the working fluid nozzle flange there is a handle which is operable by a manipulator to pull the working fluid nozzle out of the casing and to reintroduce it, respectively.

Abstract: Jet pumps and a feed water sparger are disposed in a reactor pressure vessel incorporating a core. A first feed water pipe supplies a portion of feed water to the jet pumps as their driving water. A second feed water pipe connected to the first feed water pipe supplies the remaining portion of the feed water to the feed water sparger. A first feed water heater is disposed in the first feed water pipe downstream of a connecting point of the first feed water pipe and the second feed water pipe. An amount of extracted steam introduced into the first feed water heater is controlled on the basis of a difference in the temperature between feed water flowing through the first feed water pipe and the feed water flowing through the second feed water pipe.

Abstract: Pressurized water reactor with a primary circuit including therein a reactor pressure vessel, a steam generator and a main coolant pump, and with an auxiliary system having high pressure pumps for feeding water into the primary circuit, including a line extending from an upper side of the pressure vessel and having at least one shut-off valve therein, the line connecting the reactor pressure vessel and a part of the auxiliary system wherein a lower pressure prevails than in the reactor pressure vessel.

Abstract: The invention does away with the necessity of moving parts such as a check valve in a nuclear reactor cooling system. Instead, a jet pump, in combination with a TEMP, is employed to assure safe cooling of a nuclear reactor after shutdown. A main flow exists for a reactor coolant. A point of withdrawal is provided for a secondary flow. A TEMP, responsive to the heat from said coolant in the secondary flow path, automatically pumps said withdrawn coolant to a higher pressure and thus higher velocity compared to the main flow. The high velocity coolant is applied as a driver flow for the jet pump which has a main flow chamber located in the main flow circulation pump. Upon nuclear shutdown and loss of power for the main reactor pumping system, the TEMP/jet pump combination continues to boost the coolant flow in the direction it is already circulating.

Abstract: A pressurized water nuclear reactor comprises a reactor vessel arranged in a pool made in the form of a pressure vessel, the pool being filled with a strongly neutron-absorbing liquid, for example borated water. The reactor vessel, in addition to being connected to a primary system, is provided with a lower shutdown opening, arranged below the reactor core, for pool liquid and with an upper shutdown opening, arranged above the core, for pool liquid.