Abstract: A sparger includes a main pipe connecting inside and outside of a water tank having a storage space therein for storing cooling water, so as to define a flow path through which steam and air containing radioactive materials generated outside the water tank are discharged into the cooling water, a header part connected to one end portion of the main pipe located in the storage space, and having a storage chamber in which the steam and air transferred through the main pipe are collected, and a plurality of discharge nozzles disposed in a spacing manner, each having inlet and outlet formed on one end located in the storage chamber and another end located in the storage space, respectively, to discharge the steam and air from the storage chamber to the storage space, and at least some of the plurality of discharge nozzles protruding from the header part by different lengths.

Abstract: Arrangements and devices for reducing and/or preventing wear of a thermal sleeve in a nuclear reactor are disclosed. Arrangements include a first structure provided on or in one the thermal sleeve and a second structure provided on or in the head penetration adapter. At least a portion of the first structure and at least another portion of the second structure interact to resist, reduce, and/or prevent rotation of the thermal sleeve about its central axis relative to the head penetration adapter. Devices include a base for coupling to a guide tube of the reactor and a plurality of protruding members extending upward from the base. Each member having a portion for engaging a corresponding portion of a guide funnel of the thermal sleeve.

Abstract: A nuclear reactor comprises a pressure vessel containing a nuclear reactor core. A reactor core cooling system comprises a standpipe including a plurality of orifices in fluid communication with a refueling water storage tank (RWST) to drain water from the RWST into the standpipe, and an injection line configured to drain water from the standpipe to the pressure vessel. In some embodiments the standpipe is disposed in the RWST, while in other embodiments the standpipe is disposed outside of the RWST and cross-connection pipes connect the plurality of orifices with the RWST. The reactor core cooling system may further comprise a valve configured to control flow through one orifice of the plurality of orifices in fluid communication with the RWST based on water level in the standpipe. The valve may comprise a float valve having its float disposed in the standpipe.

Abstract: A method and apparatus for extending the period a nuclear steam supply system spent fuel pool can be safely passively cooled by storing the spent fuel offloaded from the reactor, in the containment for one reactor operating cycle. During a refueling the spent fuel that is not to be returned to the reactor and the spent fuel that will be returned to the reactor are stored separately in shielded locations within the containment. After one operating cycle, the spent fuel stored within the containment that was not returned to the reactor just prior to the last operating cycle, is offloaded to the spent fuel pool and replaced by the newly offloaded spent fuel that is being retired.

Abstract: Nuclear power plant (NPP) containment building separation system dividing the NPP containment building into isolated containment building rooms. The system includes containment building separation shutters located in the circular gap which divides the containment building rooms and the containment building walls; an air supply unit connected to a manifold ring which, in turn, is connected to the air-inflated shutters designed to ensure insulation of the airspace inside the containment building rooms when inflated and to connect the airspace when deflated. In emergency mode the air supply to the air-inflated shutters is terminated, and the shutters get deflated and fully open the circular gap which ensures convection process throughout the whole area of containment building.

Abstract: The present invention discloses a nuclear reactor coolant pump that does not rely on an electric motor, but is operated by means of driving force generated inside a nuclear power plant, so a to be capable of maintaining the safety of the nuclear reactor when the nuclear reactor is operating normally and also in the event of an accident in the nuclear reactor. The nuclear reactor coolant pump comprises: a pump impeller rotatably installed in a first fluid passage of a nuclear reactor coolant system to circulate a first fluid inside the nuclear reactor coolant system; a drive unit receiving steam from a steam generator to generate driving force to rotate the pump impeller, and rotating about the same rotating shaft as the pump impeller to transfer the generated driving force to the pump impeller; and a steam supplying unit forming a passage between the steam generator and the drive unit to supply at least a portion of the steam released from the steam generator to the drive unit.

Abstract: A sealing mechanism for a reactor vessel (RV) cable penetration tube improves the functional and structural integrity of a cable inserted in an RV through a penetration tube due to use of a precise thimble. The sealing mechanism includes a penetration tube configured to penetrate an RV from an outside to an inside thereof and having a penetration hole for communication with the inside of the RV, a cable configured to be inserted in the RV through the penetration hole of the penetration tube, and a thimble placed between the cable and the penetration tube, wherein a dimple groove portion is provided on the thimble in a direction from an outer surface of the penetration hole toward the cable.

Abstract: A pressurized water reactor (PWR) includes a vertical cylindrical pressure vessel having a lower portion containing a nuclear reactor core and a vessel head defining an internal pressurizer. A reactor coolant pump (RCP) mounted on the vessel head includes an impeller inside the pressure vessel, a pump motor outside the pressure vessel, and a vertical drive shaft connecting the motor and impeller. The drive shaft does not pass through the internal pressurizer. A central riser may be disposed concentrically inside the pressure vessel, and the RCP impels primary coolant downward into a downcomer annulus between the central riser and the pressure vessel. A steam generator may be disposed in the downcomer annulus and spaced apart from with the impeller by an outlet plenum. A manway may access the outlet plenum so tube plugging can be performed on the steam generator via access through the manway without removing the RCP.

Abstract: An emission monitoring system for a venting system of a nuclear power plant is configured for low consumption of energy and high reliability. The emission monitoring system has a pressure relief line connected to a containment and contains a high-pressure section, a low-pressure section, and a sampling line. The sampling line opens into the low-pressure section of the pressure relief line and is guided from there to a functional path and through the sampling line steam flows. A jet pump containing a pump fluid connector, a suction connector and an outlet connector is provided. A pump fluid feed line has an inlet side opening into the high-pressure section of the pressure relief line and is guided from there to the jet pump and connected to the pump fluid connector. A sample return line is guided from the functional path to the jet pump and connected to the suction connector.

Abstract: An emergency core cooling system is provided with at least four active safety divisions each equipped with a motor-driven active safety system, and at least one passive safety division equipped with passive system that does not require to be electrically driven. The number of active safety divisions is grater than the number of active safety divisions needed during a design basis accident by two or more, and each active safety division is provided with one motor-driven active safety system. The passive safety system can cool the reactor core without being re-supplied with cooling water from the outside during the time period needed for the active safety system subjected to online maintenance to recover if an accident occurred during online maintenance of one active safety system.

Abstract: A passively-cooled spent nuclear fuel pool system comprising: a spent nuclear fuel pool comprising a body of liquid water having a surface level, at least one spent nuclear fuel rod submerged therein that heats the water; a lid covering the spent nuclear fuel pool to create a hermetically sealed vapor space between the surface level and the lid; and a passive heat exchange sub-system including a riser conduit comprising first and second riser inlet sections and a primary riser section that receives water vapor therefrom. Each riser inlet section has a respective inlet positioned in a respective section of the vapor space. A downcomer receives and condenses water vapor from the primary section forming condensed water vapor. A return conduit fluidly coupled to the downcomer and having an outlet located in the body of liquid water returns the condensed water vapor thereto.

Abstract: A steering gear mechanism for motor vehicles may include a steering system housing in which a toothed rack is mounted and displaceable along a longitudinal axis. The toothed rack may be connected to steerable wheels of a motor vehicle and configured to pivot the steerable wheels. The toothed rack can include a first toothed segment that meshes with a first pinion of a pinion shaft, with the pinion shaft being connectable to a steering wheel via an input shaft. The toothed rack may further include a second toothed segment that is situated opposite the first toothed segment with respect to the longitudinal axis and engages with a second pinion. Further, an electric motor can drive the first pinion in a first direction, which by way of direct or indirect coupling causes the second pinion to rotate in a second direction opposite the first direction. The electric motor may drive a gear mechanism shaft that surrounds the pinion shaft and is connected to the pinion shaft by way of a gear mechanism.

Abstract: A nuclear reactor cooling system with passive cooling capabilities operable during a reactor shutdown event without available electric power. In one embodiment, the system includes a reactor vessel with nuclear fuel core and a steam generator fluidly coupled thereto. Primary coolant circulates in a flow loop between the reactor vessel and steam generator to heat secondary coolant in the steam generator producing steam. The steam flows to a heat exchanger containing an inventory of cooling water in which a submerged tube bundle is immersed. The steam is condensed in the heat exchanger and returned to the steam generator forming a closed flow loop in which the secondary coolant flow is driven by natural gravity via changes in density from the heating and cooling cycles. In other embodiments, the cooling system is configured to extract and cool the primary coolant directly using the submerged tube bundle heat exchanger.

Abstract: The closure element includes a tensioning pin which can be tensioned and a head part of which forms a closure disc that can be spread apart by the tensioning pin. The closure disc is pressed, in the installed state, against an inner wall of the bore to be closed. When a specific tensile stress is reached, the tensioning pin is separated from the closure disc at a predetermined breaking point of the tensioning pin. The easy-to-handle tensioning pin facilitates the installation of the closure in the bore in the component. Since the closure disc is pressed against an outer counterholder during the installation process, it can be inserted into a continuously smooth bore. The limitation of the tensile stress effected by way of the predetermined breaking point also ensures that the bore is closed with a defined closing force.

Abstract: A permanent seal for a refueling canal of a nuclear power plant. The seal includes a support structure and a membrane. The support structure includes a first annular plate with ribs connected to and extending from a lower surface of the annular plate. The support structure is positioned atop the shield wall on the refueling canal floor, encircling and positioned near the annulus. The membrane includes a first end that is connected to the seal ledge and a second end that is connected to the refueling canal floor. The membrane has a stepped profile, with side walls extending substantially perpendicularly from a central annular plate to form a pocket configured to fit over the support structure. Loads imparted to the membrane are transferred through the support structure annular plate and ribs to the refueling canal floor.

Abstract: A method for retracting in-core instrument thimble tubes from the reactor core prior to refueling a nuclear reactor with top mounted instrumentation. The apparatus includes a penetration flange interposed between the head flange and the reactor vessel flange through which the instrumentation cabling passes. The penetration flange is connected to the upper internals and is raised relative thereto to retract instrumentation thimbles from the core prior to removal of the upper internals from the reactor vessel for refueling. The penetration flange is removed from the vessel with the upper internals.

Abstract: A sealed stopper for an opening in a tubing for joining a chamber and a piping including a fastening ring is provided. The stopper includes a rigid bearing plate and a sealing member carried by the bearing plate, and includes a seal having a planar and flexible central portion with a reduced thickness extending below the bearing plate and a peripheral portion radially deformable by a central expander of the peripheral portion against the inner surface of the fastening ring.

Abstract: Apparatus and a method for retracting in-core instrument thimble tubes from the reactor core prior to refueling a nuclear reactor with top mounted instrumentation. The apparatus includes a penetration flange interposed between the head flange and the reactor vessel flange through which the instrumentation cabling passes. The penetration flange is connected to the upper internals and can be raised relative thereto to retract instrumentation thimbles from the core prior to removal of the upper internals from the reactor vessel for refueling. The penetration flange is removed from the vessel with the upper internals.

Abstract: A plug for heat-conducting tubes is equipped with: a plug main body, which is formed so as to be capable of being inserted into the heat-conducting tubes; a columnar member, which is capable of being inserted into and removed from the plug main body from the cylindrical open end of the plug main body, and has at its outer circumference a tapered surface; and a wedge member, which is formed so as to be capable of being inserted into and removed from the plug main body from the cylindrical open end of the plug main body, and has at its inner circumference a tapered surface which opposes the tapered surface of the columnar member when the wedge member is inserted into the plug main body.

Abstract: Internal head vents are usable in nuclear reactors and include piping inside of the reactor pressure vessel with a vent in the reactor upper head. Piping extends downward from the upper head and passes outside of the reactor to permit the gas to escape or be forcibly vented outside of the reactor without external piping on the upper head. The piping may include upper and lowers section that removably mate where the upper head joins to the reactor pressure vessel. The removable mating may include a compressible bellows and corresponding funnel. The piping is fabricated of nuclear-reactor-safe materials, including carbon steel, stainless steel, and/or a Ni—Cr—Fe alloy. Methods install an internal head vent in a nuclear reactor by securing piping to an internal surface of an upper head of the nuclear reactor and/or securing piping to an internal surface of a reactor pressure vessel.

Abstract: An improved permanent seal for a refueling canal of a nuclear power plant is disclosed and claimed. The seal includes a support structure and a membrane. The support structure includes a first annular plate with a number of ribs connected to and extending from a to surface of the support structure annular plate. The support structure is positioned atop the shield wall on the refueling canal floor, encircling and positioned near the annulus. The membrane includes a first end that is connected to the seal ledge and a second end that is connected to the refueling canal floor. The membrane has a stepped profile, with side walls extending substantially perpendicularly from a central annular plate to form a pocket configured to fit over the support structure. Loads imparted to the membrane are transferred through the support structure annular plate and ribs to the refueling canal floor.

Abstract: [Problem to be Solved] To easily perform assembly at the time of plugging an inspection hole.

Abstract: A sealing device for a device for measuring a fill level in a fluid container, particularly in a pressure container of a nuclear facility, includes at least one thermocouple which is connected by a pressure pipe to the pressure container and a pipeline connected to the pressure pipe to an evaluation unit. The pressure pipe and the pipeline are connected to each other by a pipe screw connection including a central part having two threaded pieces. One threaded piece is connected by a screw connection to a pipe sleeve and the other threaded piece is connected by a further screw connection to the pressure pipe.

Abstract: A covering for a containment pool, tank or enclosure, in particular a containment enclosure for a nuclear power plant, is produced by placing metal sheets parallel to a first wall at a predetermined distance from the latter, each sheet comprising anchoring elements, on a first face arranged facing the first wall, placing a rail situated between the anchoring elements and comprising side walls and a base delineating a space facing the area to be welded with two adjacent sheets, making a weld bead by full-penetration butt welding of the adjacent metal sheets, and pouring concrete between said first wall and the metal sheets, the anchoring elements of the metal sheets being completely independent from the weld bead after the concrete has been poured.

Abstract: A boiling water reactor assembly includes a bayonet plate closure between a control rod guide tube and a drive housing pipe. The bayonet plate closure has a bayonet plate constructed in two parts including a central bayonet ring mounted rotatably about its longitudinal axis and an outer ring completely surrounding the bayonet ring. The outer ring is mounted on the periphery of the bayonet ring and reaches inwards under the bayonet ring periphery. The ring is furthermore permanently supported in the axial direction on the drive housing pipe by spring pressure acting on the control rod guide tube, in order to produce a frictional connection. The spring pressure can be released unhindered from the reactor side by tools.

Abstract: A compression sleeve for use in BWR jet pump sensing line repairs is configured to maintain its physical characteristics in an operating nuclear reactor environment. The sleeve includes shaped ends to accommodate deformation and flow of the sleeve so as to form a seal between jet pump sensing line components. A mechanical coupling assembly for repairing a jet pump sensing line is configured to include the compression sleeve.

Abstract: A locking mechanism for securing hatches internal to a steam generator that is made up of only mechanical locking elements with fully captured moving parts. The mechanism employs a locking pin with redundant mechanisms to secure the pin in the closed position. The moving parts of the device can be attached directly to a removable hatch so that installation and repairs that may be required can be performed outside of the pressure vessel of the steam generator.

Abstract: The invention relates to a sealing element fastening system for at least one sealing element of a pressure vessel, which has at least one opening and a sealing part, in particular a cover, provided for the opening. In the operating state of the pressure vessel each sealing element is at least partially inserted in an accommodating groove in the sealing part and corresponding sealing element fastening devices are positioned in each case in an indentation in the sealing part. The indentations are in each case sealed by a fill element in the operating state of the pressure vessel.

Abstract: A nuclear reactor having a penetration seal ring interposed between the reactor vessel flange and a mating flange on the reactor vessel head. Radial ports through the flange provide passage into the interior of the reactor vessel for utility conduits that can be used to convey signal cables, power cables or hydraulic lines to the components within the interior of the pressure vessel. A double o-ring seal is provided on both sides of the penetration flange and partial J-welds on the inside diameter of the flange between the flange and the utility conduits secure the pressure boundary.

Abstract: A pump leakage mitigation device includes one or more clamp arms on an outer surface of a pump that can be driven by a biasing element to seat against a shaft of the pump to seal or reduce fluid flow through a breakdown of the pump. The biasing element engages only at threshold temperatures, such as those associated with breakdown orifice failure when additional sealing may be necessary. Clamp arms of any number and shape can be used to achieve the desired seal and based on the pump geometry. A sealant surface and/or keeping mechanism are useable with the leakage mitigation device to enhance fluid flow blockage throughout a pump failure transient scenario. Pump leakage mitigation devices are installed on an outside of a variety of different pump types and can thus be installed, actuated, manipulated, disengaged, and/or removed without having to destroy or disassemble the pump.

Abstract: Disclosed are the apparatus and methods for closing a canister that stores and transports spent nuclear fuel. In one embodiment, the canister includes a canister shell that includes an open end. A closure lid is inserted within the open end of the canister shell. The closure lid engages the open end of the canister shell to provide a weld area that is substantially on the outer circumference of the closure lid. The weld area includes a first weld layer and a second weld layer. The first weld layer welds the closure lid to the canister shell at the weld area and closes the canister. The second weld layer also welds the closure lid to the canister shell at the weld area, providing a redundant closure seal, and is disposed substantially on top of the first weld layer. The method for closing the canister is provided herein.

Abstract: A shut-off device for a nuclear reactor component duct is provided that includes a plurality of elastic sealing rings, each radially expandable with respect to a common longitudinal axis between a retracted position at a distance from a wall of the duct and an expanded position for leaktight contact with the wall of the duct; a device provided for selectively moving the sealing rings between their retracted positions and their expanded positions; at least one member for locking in position the shut-off device in the duct to be shut off, distinct from the sealing rings, radially expandable with respect to the central axis between a retracted position in which the locking member is moved away from the wall of the duct and a locking position in which the locking member bears against the wall of the duct; a device provided for selectively moving the locking member between its retracted position and its locking position.

Abstract: An electrical switching apparatus is for another apparatus including a number of insulators, a number of temperature sensors operatively associated with the number of insulators, and a number of conductors operatively associated with the number of insulators. The electrical switching apparatus includes a number of separable contacts, an operating mechanism structured to open and close the separable contacts, a number of sensors structured to sense a number of currents flowing through the separable contacts and through the conductors, a processor structured to input the sensed currents from the sensors, and an output. The processor calculates at least one of: (a) a thermal age of the other apparatus from a number of sensed temperatures from the temperature sensors, and (b) the thermal age of the other apparatus from the sensed currents. The output includes the thermal age of the other apparatus.

Abstract: A system and method for reducing tritium migration. In one aspect, the invention is a method of reducing tritium mitigation from a spent nuclear fuel pool containing a body of tritiated water having an exposed surface, the method comprising hermetically sealing the exposed surface of the body of tritiated water with a cover movable between an open-state and a close-state.

Abstract: A sealing device for a device for measuring a fill level in a fluid container, particularly in a pressure container of a nuclear facility, includes at least one thermocouple which is connected by a pressure pipe to the pressure container and a pipeline connected to the pressure pipe to an evaluation unit. The pressure pipe and the pipeline are connected to each other by a pipe screw connection including a central part having two threaded pieces. One threaded piece is connected by a screw connection to a pipe sleeve and the other threaded piece is connected by a further screw connection to the pressure pipe.

Abstract: An opening and closing device that opens and closes an access port opened from a substantially cylindrical working platform disposed inside a reactor vessel and used to access a nozzle stub of the reactor vessel from the inside of the working platform, the opening and closing device includes: a cover that is slidable along an outer peripheral surface or an inner peripheral surface of the working platform from a closing position where the access port is closed to an opening position where the access port is opened; and moving device for sliding the cover.

Abstract: Sealing means comprising a seal carrier and a seal connected thereto, wherein the seal carrier is removably fixable between two areas insulated from each other, and a transfer device between two chambers, which are separated by a wall, wherein said transfer device comprises a transfer mechanism and at least one sealing means according to the invention which is positioned between the wall and the transfer mechanism.

Abstract: [Problem to be Solved] To easily perform assembly at the time of plugging an inspection hole.

Abstract: A heating laser beam is emitted to a cracked portion to remove moisture from the cracked portion, and subsequently, a welding laser beam is emitted to the cracked portion to heat and melt the cracked portion. The heating laser beam and the welding laser beam are emitted to an entire surface of the cylindrical body inside the reactor such as a stub tube penetrating through and fixed to a reactor bottom portion and a crack of the welded portion between the cylindrical body and the reactor bottom portion to thereby prevent a new crack from occurring and reactor water from leaking.

Abstract: A permanent cavity seal ring that replaces the function of the temporary cavity seal ring typically used in narrow thermal expansion gap pressurized water reactors, to seal the gap between the reactor cavity well and the reactor during refueling. The permanent seal ring uses a C-shaped flexure that is shielded by a rigid cantilevered support arm from any accidentally dropped equipment from above in the refueling canal. The construction accommodates the thermal expansion of the reactor vessel while permitting the reactor cavity cooling air to exit the annulus between the vessel and the reactor cavity wall during plant operation, without a significant increase in pressure drop.

Abstract: Sealing means comprising a seal carrier and a seal connected thereto, wherein the seal carrier is removably fixable between two areas insulated from each other, and a transfer device between two chambers, which are separated by a wall, wherein said transfer device comprises a transfer mechanism and at least one sealing means according to the invention which is positioned between the wall and the transfer mechanism.

Abstract: The invention relates to a device (20) for shutting off an inner orifice of a bundle wrapper of a steam generator comprising a movable shaft (21) comprising a pair of lower half-flanges (25, 26), a pair of upper half-flanges (27, 28) which can be rotated by the said shaft (21) substantially through 180° between a low position facing the lower half-flanges (25, 26), for introduction into the orifices of the casing and the wrapper of the steam generator, and a high position opposite the said lower half-flanges (25, 26), and means (22) for clamping the lower half-flanges (25, 26) and the upper half-flanges (27, 28) on the peripheries arranged on either side of the inner orifice, in order to shut off this inner orifice. The invention also relates to a shutting-off method and to a tooling for installing and removing the shut-off device.

Abstract: The invention is a support system for use with a reactor vessel that defines a reactor zone and has an inlet manway providing an opening into the reactor zone. The support system comprises a manway insert that is supported by the inlet manway and extends through the opening of the inlet manway and into the reactor zone. Attached to the manway insert is attachment means for connecting a support hanger to the manway insert and for transferring the load from the support hanger to the manway insert. The support hanger has an upper end and a lower end with the upper end being fixedly attached to the attachment means and the lower end being fixedly attached to support structure means for supporting a load.

Abstract: A compression sleeve for use in BWR jet pump sensing line repairs is configured to maintain its physical characteristics in an operating nuclear reactor environment. The sleeve includes shaped ends to accommodate deformation and flow of the sleeve so as to form a seal between jet pump sensing line components. A mechanical coupling assembly for repairing a jet pump sensing line is configured to include the compression sleeve.

Abstract: A nuclear reactor including: a vessel including at least two parts; a reactor core placed in the vessel and containing fuel rod assemblies; at least one internal structure located within the vessel and having a flange portion sandwiched between the two parts of the vessel; an insertion unit for inserting a neutron-absorbing liquid in the fuel rod assemblies, placed in the vessel; and external control devices placed outside the vessel and connected to the insertion unit through conduits placed inside the internal structure, including the flange portion, wherein the insertion unit comprises a transmission unit partly placed in the conduits.

Abstract: In a method for sealing a hollow, elongate member within a reactor pressure vessel of a nuclear reactor, a section of the elongate member may be removed to separate the elongate member into an upper portion and a lower portion with an opening there between. The lower portion may be attached to a surface of the reactor pressure vessel in-situ, so as to seal off a potential leakage path through the elongate member.

Abstract: The invention relates to a guide tube especially for an instrumentation lance extending into a reactor pressure vessel. The guide tube includes a lower tube section and an upper tube section that extends into the interior of the reactor pressure vessel. In order to prevent radioactively contaminated particles from reaching the lower tube section disposed outside the reactor pressure vessel from forming a source of radiation, a separator is arranged in the upper tube section. The separator has a separation chamber in which the particles are deposited and are removed from the water.

Abstract: A method and apparatus is disclosed for smoothly inserting a fuel rod loader through the skeleton of a fuel cell and then for pulling an attached fuel rod into the fuel rod skeleton while keeping the fuel rod under constant tension and preventing the bowing of the fuel rod. The pulling mechanism comprises a smooth collet with a smooth bullet end cap for guiding the puller mechanism into and through the skeleton where the bullet end cap is removed and the fuel rod is attached with a unique ball and slide mechanism actuated by a long puller rod that grabs the end of the fuel rod by a forward motion of the puller rod and is easily removed from the fuel rod by reversing this motion once the fuel rod is in place.

Abstract: A reactor closure head assembly has guide tube nozzles which are integral with the reactor closure head. A dome-shaped forging having a concave surface is prepared with extra thickness equal to or greater than the desired nozzle height. Nozzles having bores therethrough are machined opposite the concave surface. Weld buttering is applied to the ends of the nozzles, the concave surface is clad with a corrosion resistant layer, and the forging is then heat treated. A guide tube flange is attached to the ends of the nozzles. The surfaces of the nozzle bores are covered with a protective layer which is preferably applied without heating, for example by electrochemical deposition, thereby avoiding the need for subsequent post weld heat treatment.

Abstract: The method facilitates sealing a control rod drive (CRD) housing to a stub tube in a reactor pressure vessel of a nuclear reactor, if any cracks develop proximate a heat affected zone of the stub tube at a CRD housing re-attachment weld. The method includes cutting the CRD housing to separate an upper portion of the CRD housing from a lower portion of the CRD housing. The lower portion remains in place and in substantial alignment with the upper portion of the CRD housing. A lower portion member, which may be the lower portion that was cut, is re-attached to the reactor vessel by a re-attachment weld at a location below potential differential leakage paths along the CRD housing. The heat affected zone (e.g., at the re-attachment weld) is covered with a corrosion resistant material to prevent future leaking, and to protect the weld from inter-granular stress corrosion cracking (IGSCC).