Abstract: A device for closing and sealing a lead-through (1), comprising means intended to open, clean and again close the lead-through. A cone (2) with a head (21), a rod-shaped part (22) and a sealing surface (23) arranged between said head and said rod-shaped part is arranged with the head inserted into the lead-through. In the end of the cone opposite to the head, the cone is provided with means (24) for connecting the cone to a flush pipe (5) arranged in the form of an extension of the rod-shaped part of the cone. An annular flange (3) is attached to the lead-through and around said rod-shaped cone, inserted into the lead-through, to retain the head of the cone in the lead-through. A sealing surface (31), arranged on the annular flange in the form of a seat, is adapted to correspond to and make contact with the sealing surface of the cone to close and seal the lead-through.

Abstract: The device includes a removable supporting end piece (26) which comes to rest on the top end part of a support assembly (21) fixed to the end of a port adapter of the head of the vessel of a nuclear reactor, and a pressure plate (28) including an odd number of lifting screws (31), so as to move the instrumentation column (22) upward and to clamp it against a support surface (24). A tightening assembly (35) for the lifting screws includes a tightening spindle (42a) having an end part (45) shaped to receive a tool (40) for rotating the spindle, and in turn rotates tightening spindles mounted so as to idle in the mounting plate (38) of the tightening assembly (35). The tightening spindles comprise shaped end parts (46a) coming into engagement with drive parts (31b) of the lifting screws (31) of the pressure plate (28), so as to tighten all the lifting screws simultaneously.

Abstract: A bellows-like construction which automatically extends upon immersion in water, is used to provide a relatively inexpensive water-tight enclosure for lifting equipment and the like. The lower end of the bellows is connected to the top of a rigid tubular member which extends up from a hook box or like type of structure, in a manner to form a hermetic seal. The upper end of the bellows-like arrangement is provided with a buoyant member which provides sufficient lift that, when the lifting equipment is lowered into the water to a predetermined depth, the buoyant member floats on the surface of the water in a manner which elongates a corrugated tubular portion of the arrangement and prevents radioactive water from spilling over into the box thus preventing contamination of a hook, hook block and associated apparatus which are enclosed therein.

Abstract: In order to provide a relatively inexpensive water-tight telescopic enclosure which can extend automatically upon demand, a tubular extension piece is reciprocally mounted on a container-like hook box structure. A tube seal which interconnects the hook box and the tubular extension provides a watertight connection between the two members and also provides an air space in a folded portion in which air can collect and produce buoyancy as the hook box is lowered into water. The tubular extension also has a larger cross-sectional area than the hook box and thus produces additional buoyancy. When the hook box is lowered into water the extension piece automatically floats upwardly to prevent the intrusion of water into the interior of the hook box and thus prevent contamination of pieces of apparatus enclosed therein.

Abstract: A system is directed for remotely securing a canopy seal about a broken omega seal site between the control drive mechanism and the adapter tube of a nuclear reactor vessel so as to contain any radioactive leakage therebetween. The system includes a stalk measuring device for initially measuring the diameter of the adapter tube, a split canopy installation fixture which is adjusted according to the measurement detected by the stalk measuring device to position a two-piece canopy seal about the omega seal site, and a robotic weld arm for performing the upper and lower radial welds about the canopy seal as well as C-shaped vertical welds between the two-piece canopy seal.

Abstract: A nuclear reactor vessel cavity seal plate. An annular support plate is positioned over the cavity between the reactor vessel and the shield structure and seal welded to the shield structure. Inner and outer support rings attached to the annular plate are supported by the existing beams in the annular cavity. A U-shaped flexible annular expansion ring positioned between the annular plate and reactor vessel flange has its inner diameter seal welded to the reactor vessel flange and its outer diameter seal welded to the annular plate. Ports in the annular plate provide access to nuclear instruments below the annular plate. A cover plate is removably attachable to each port to seal the ports. A closable drain is provided in the annular expansion ring. This provides a permanent seal plate that allows flooding of the cavity for refueling with it being necessary to remove only the cover plates for normal reactor operations.

Abstract: A shutdown cooling system for a nuclear reactor operates during lapse of normal power and emergency power and has an independent power source fo removing residual heat while cooling the seals of the main reactor coolant pump. A high pressure pump delivers cooling water to the reactor cooling pump seals, a low pressure pump circulates core coolant, and a cooling mechanism discharges the decay heat. Electrical power for the pumps and associated valves and controls is provided by a dedicated power source apart from the regular residual heat removal apparatus of the reactor, and apart from the emergency generators provided for regular power failure backup.

Abstract: A nozzle dam automatically latches on an annular ledge surrounding the nozzle opening. A pivotal latch arm on the dam, biased to the locked position is forced toward the unlocked position by a cam on the ledge as the nozzle is pressed on the ledge, and snaps into engagement with the ledge when the dam is fully seated over the opening. A bias arm may be operated by a wrench to pivot the latch arm toward the unlocked position until a detent locks the latch arm in the unlocked position.

Abstract: A nuclear reactor containment arrangement has a permanent seal ring across the thermal expansion gap defined by the reactor vessel wall and the containment wall. The seal ring allows for lateral translation of the reactor vessel, in addition to radial and axial expansion and contraction. The seal ring features an outer attachment arrangement characterized by a radially corrugated cylinder extending vertically between two annular Belleville plates having different diameters. The corrugations of the cylinder extend longitudinally between the cylinder edges, and flex during lateral movement of the reactor vessel relative to the containment wall. The Belleville plates accommodate axial expansion and contraction of the vessel, and an inner attachment arrangement accommodates radial expansion and contraction.

Abstract: The method of repairing in situ a damaged or malfunctioning electrical connector (10) of a safety related nuclear reactor instrument (14) and its associated sheathed cable (18) wherein the damaged or malfunctioning connector portion (20) is cut from its associated cable (18) and replaced by a new connector portion. The wires of the cut cable are connected with the replacement connector portion and are suitably insulated. The cut cable and new connector portion are then secured together by a special alloy coupling (34) which is positioned in spanning relation with the cut cable (18) and the replacement connector portion (20). This special alloy has the property that it can be expanded within limits and upon being heated above a critical temperature will return to its original dimension. The tubular coupling accordingly has an expanded diameter slightly larger than that of the replacement connector portion and the sheath of the cut cable but an original inner diameter slightly smaller.

Abstract: A device for sealing a penetration in a pressurizer of a nuclear steam supply system includes a hollow cylinder adapted to be inserted into the heater sleeve, in place of the heater. The cylinder includes a nose portion formed with a number of axially extending slots defining therein a number of radially displaceable segments, each of which has an outwardly extending flange, proximate its distal end, which is engageable with the heater sleeve to resist blowout. A rod, inserted into the cylinder, seals the passage therethrough while locking the displaceable nose portion segments in their sleeve-engaging position. An annular soft nickel band on the outside of the cylinder engages the inner surface of the heater sleeve to provide an effective seal therebetween.

Abstract: Self-locking plug for plugging a hole defined by a surrounding structure, which structure may be a nuclear power reactor pressure vessel core barrel flange. When the hole is plugged, transient hydraulic forces generated in the pressure vessel will tend to force the plug from the hole. The plug includes a plug body sized to be disposed in the hole and a locking member pivotally connected to the plug for locking the plug body to the flange, so that the plug is not inadvertently forced from the hole by the transient hydraulic forces. A cam, which is capable of engaging the locking mechanism for outwardly pivoting the locking mechanism, is slidably connected to the plug body. A movable piston is connected to the cam for driving the cam into engagement with the locking mechanism. Moreover, the locking mechanism pivots to engage the flange as the cam engages the locking member. A ram, which is also connected to the plug body, is provided to ram the plug body into the hole for snugly plugging the hole.

Abstract: A permanent annular ring seal and refueling deck assembly providing an effective water barrier over the annular space between a nuclear reactor vessel flange and a surrounding annular ledge includes annular platform, a support and a joint seal.The joint seal has an upper straight walled cylindrical section and a lower flexible coil or arcuate shaped section which provides for greater accommodation of vessel radial, axial and rotational movements, and reduces joint stress.

Abstract: A system is directed for remotely securing a canopy seal about a broken omega seal site between the control drive mechanism and the adapter tube of a nuclear reactor vessel so as to contain any radioactive leakage therebetween. The system includes a stalk measuring device for initially measuring the diameter of the adapter tube, a split canopy installation fixture which is adjusted according to the measurement detected by the stalk measuring device to position a two-piece canopy seal about the omega seal site, and a robotic weld arm for performing the upper and lower radial welds about the canopy seal as well as C-shaped vertical welds between the two-piece canopy seal.

Abstract: Apparatus for sealing a joint between an inclined base surface having a leak path and a mating end surface of a hollow body surrounding the leak path. Compression gasket means receive an asymmetric preload force applied through the hollow body from an environmental pressure preloading element having a variable spring constant in register with the joint. The preloading element is a ring-shaped body of a given thickness of an asymmetric radial structure defined by a plurality of unlike radially inwardly directed through slots open to its periphery and axially stacked.

Abstract: A plug assembly for plugging the flow hole of a core support barrel employs a pair of plug members which are initially collapsable to permit positioning between the core support barrel and the adjacent thermal shield. The plug assembly is activated to a projected plugged configuration by pneumatic or hydraulic pressure to provide a sealing engagement by a cooperative arrangement between circumferential locking barbs and a sealing lip.

Abstract: A shielded access door for a nuclear steam generator manway port having a beam of radiation streaming therethrough, the port being surrounded by a manway flange. The door comprises a bracket adapted to be removably connected to the flange. A plurality of swing arms have the first end portion thereof pivotally connected to the bracket. A first shield member is connected to the second end portions of the arms and is disposed parallel and adjacent to the port for shielding against the beam of radiation. The first shield member and the port define a gap therebetween for allowing access to the steam generator interiorly of the port while simultaneously shielding against the beam of radiation. The first shield member has a ventilation hole therethrough in communication with the port for ventilating the port, so that air-borne radioactive particles present interiorly of the steam generator are exhausted from the steam generator.

Abstract: An apparatus and method for plugging an access hole in a steam generator, having a shell, a wrapper, and an annulus positioned between the shell and the wrapper, includes attaching a plate, having a first mating connection and at least one aperture, to the wrapper of the steam generator. A plug, having a second mating connection and at least one aperture, is positioned within a bore of the plate. The plug is rotated approximately 90.degree. for engaging the first mating connection of the plate with a second mating connection of the plug and for aligning the aperture of the plug with the aperture of the plate. A sleeve, having a bore therethrough and at least one aperture, is positioned on the plug and the aperture of the sleeve is aligned with the apertures of the plate and the plug. A pin is installed in the aligned apertures of the plate, the plug, and the sleeve. A retaining nut is positioned on the plug after installation of the sleeve.

Abstract: A fastener structure for fastening together a plurality of members, such as the plurality of members comprising a tube plug, and a method for plugging an opening in a solid member, which may be a tube, for preventing the flow of fluid through the opening in a solid member or through the tube, such as a nuclear steam generator tube, comprises a first member, such as a shell, a second member, such as bolt structure, and locking structure. A deformable tab portion of the locking structure may have an undercut positioned so that when the second member is installed within the first member, a first surface of the undercut is bent toward a second surface of the undercut thereby plastically deforming the tab portion into a recess in at least one of the first and the second members for automatically securing together the plurality of members.

Abstract: A remotely controlled robotic welding arm is provided that is designed to service the omega seal site between the control rod drive mechanism and adapter tube of a nuclear reactor stalk head and is specifically concerned with welding the canopy seal to contain radioactive steam released in the event of an omega seal failure.

Abstract: A plug assembly for plugging the flow hole of a core support barrel employs an offset arm for securing the plug to the core support barrel above the flow hole and the adjacent thermal shield. The disclosed embodiments do not require the cutting of an access opening through the thermal shield.

Abstract: A nuclear reactor vessel cavity seal plate. An annular support plate is positioned over the cavity between the reactor vessel and the shield structure. The inner diameter of the support plate rests freely upon the reactor vessel flange to allow movement of the vessel thereunder during thermal expansion and contraction. A flexible annular seal positioned over the support plate has its inner diameter seal welded to the reactor vessel flange and its outer diameter seal welded to the shield structure. Matching ports in the support plate and seal provide access to nuclear instruments below the support plate. A mounting block around each port accepts a cover plate that seals the port. This provides a permanent seal plate that allows flooding of the cavity for refueling with it only being necessary to remove the cove plates for normal reactor operations.

Abstract: A method for sealing a leak between a control rod drive (CRD) stub tube (3) arranged in a reactor wall (2) and a tubular CRD housing (1) extending through the CRD stub tube (3) and the vessel wall (2). According to the invention, this sealing is obtained by deforming a suitably shaped element of memory metal below the transition temperature of the memory metal in such a way that it can be inserted, in the form of a sleeve (5) or a ring, into or around the CRD housing (1) where said housing passes through the vessel wall (2), or alternatively replace part of the CRD housing (1) at the passage through the vessel wall (2). Then when the memory metal is heated to above the transition temperature, it strives to resume its original shape which shall then have been such that the desired seal is obtained.

Abstract: A plugging device, such as a tube plug, and method for plugging a tubular member, such as a nuclear steam generator tube, comprises a locking cup for securing together the plurality of members comprising the tube plug. The plugging device may comprise a first member, such as a shell of a tube plug, a second member, such as bolt means of a tube plug and an annular locking cup disposed in a bore of the first member and having outside diameter threads. The outside diameter threads of the locking cup have a deformed portion with a wave-like pattern for providing resistance during threading and unthreading of the locking cup into and out of the first member. At least one of the second member and the locking cup has at least one recess for receiving a deformable portion of the other of the second member and the locking cup for securing the first member, the second member, and the locking cup together.

Abstract: Method and apparatus for maintaining a water level which immerses heat exchanger tubes, containing radioactive emitting material, within an inner shell of a steam generator while permitting space between the inner shell and a coaxial outer shell to be free of water during operations performed by workmen in such space after the apparatus is installed thereby reducing exposure of the workmen to harmful radiation. Seal support segments are installed around the inner shell at the lower end of the space and in engagement with the inner and outer shells. A pair of inflatable tubes are placed end-to-end on the support segments so as to encircle the inner shell. Seal retention segments which, together, form a ring around the inner shell are placed on the inflatable tubes and the latter tubes are inflated to form a water tight seal between the shells.

Abstract: The fixed structure (10) incorporates an abutment surface (10a) upon which a corresponding abutment surface (8a) of the transportable element (1) comes to bear, with the interposition between the abutment surfaces (8a, 10a) of at least two concentric annular sealing joints (13a, 13b). The pressure in the space (18) between the sealing joints (13a, 13b) and bounded by the abutment surfaces (8a, 10a) is measured during the emplacement of the transportable element (1) to determine whether it is leakproof. The measured maximum pressure and/or the variation of pressure measured over time is compared with predetermined values corresponding to a correct emplacement of the transportable element (1).

Abstract: Apparatus for sealing or blocking conduits, such as the primary nozzles of a nuclear steam generator. The invention includes an annular bracket sealingly attached to the rim of the open end of the nozzle, the bracket having a plurality of threaded holes therein. Mounted atop the bracket is a generally circular nozzle dam that includes a first side section hingedly pivotably connected to a second side section for allowing the nozzle dam to be foldable. Removably connected to each side section is a center section, the center section and the side sections defining the generally circular nozzle dam for covering the opening defined by the annular bracket. The periphery portions of the center section and of the side sections have bores therethrough. A plurality of threaded bolts extend through the bores in the nozzle dam and into the threaded holes in the bracket for removably bolting the nozzle dam to the bracket.

Abstract: The device comprises, in positions adjacent to the bearing surface (15) of the transportable container (1) on the fixed structure, a first member (16) for plugging the central channel (3) of the container (1), and a second member (17) for plugging the upper end of the well (18). These members are arranged inside a zone of contact of at least one o-ring seal (13) with the bearing surface (15). Each of the plugging members (16, 17) comprises a planar surface arranged, in its closing position, in the planar bearing surface (15) of the container or in the planar bearing surface of the fixed structure, respectively. At least one of the plugging members (16, 17) can move in the axial direction of the well (18) and of the central channel (3) of the container (1) and in a transverse direction perpendicular to the axial direction, between its closing position and its opening position.

Abstract: A pump assembly which overcomes a shaft and cover cracking problem comprising a means for heating the seal purge water flowing along the shaft before it exits into an annulus (mixing region) thus reducing the temperature difference between the cooler seal purge water and the hotter product water prior to the mixing of the two waters.

Abstract: A plug and method for plugging a penetration in a pressure vessel wall having a sleeve protruding through the penetration. The sleeve is cut at a point between the interior and exterior surfaces of the pressure vessel wall. The cut portion of the sleeve extending beyond the exterior surface of the pressure vessel wall is removed. A plug sized to fit within the penetration is inserted into the penetration so that one end of the plug is flush with the exterior surface of the pressure vessel wall. A weld pad is deposited on the end of the plug and the exterior surface of the pressure vessel wall.

Abstract: The invention relates to a sealing joint for pipes (3) or pipe sockets (2) in, for example, a nuclear reactor. The joint comprises at least two sealing bodies (4, 5) contacting each other in a contact surface (8) and provided with through holes (6, 7). The holes (6, 7) are delimited by envelope surfaces (9, 10) and form a tubular channel (11) through the sealing bodies (4, 5) and the contact surface (8). The sealing bodies (4, 5) are displaceable in relation to each other along the contact surface (8). Around the channel (11) a sealing member (12) is arranged between the sealing bodies (4, 5). Each one of the sealing bodies (4, 5) is divided into at least two discs (4a, 4b; 5a, 5b, respectively) in a plane intersecting the associated envelope surface (9, 10) along a closed curve. Between the discs belonging to a sealing body (4, 5), a slot (13 ) has been provided which is delimited by the associated envelope surface (9, 10). A flexible sealing ring (13a) is inserted into the slot (13).

Abstract: The invention relates to a sealing sleeve for sealing a leak in, for example, a pipe, a pipe socket or the like in a nuclear reactor. The sleeve comprises a bellows-like mid-portion (1) with annular ends, at least these or part of these (2) being made of a memory metal with a suitable transition temperature. At a temperature above the transition temperature, that part of these annular ends which consists of memory metal has been given an inner diameter suitable for achieving sealing around the relevant pipe section on each side of the leak. The mentioned part of the ends has thereafter, at a temperature below the transition temperature, been deformed into a diameter which permits the sleeve to be freely fitted onto the pipe. In fitted position, the sleeve is then heated to above the transition temperature, the memory metal then striving to recover its previous shape and shrinks the sleeve so as to obtain sealing.

Abstract: The shutoff device consists of a housing (14) inserted in the conduit, in which a movable shutter (32) is mounted for oscillation about a horizontal axis (33) in the housing (14) and comprising a closing member (35) returned into a position of closing a channel (28) by a counterweight (36). A manometer (43) enables the pressure inside the housing (14) to be measured. The shutoff device, wholly passive in operation, can be employed in particular in a conduit for guiding a measurement probe employed in a pressurized water nuclear reactor.

Abstract: A nuclear steam generator 10 with economizer 32 adjacent secondary side feedwater inlets 38a and 38b includes a secondary side divider plate 36 and handholes 40 at opposing 180.degree. locations in alignment with the ends of the plate 36. Notches 42 in the ends of the plate 36 adjacent the aligned handholes 40 facilitate inspection and maintenance access on the secondary side above tubesheet 22. To prevent bypass flow from one side of the divider plate 36 to the other, a novel flow blocker 50 of cylindrical shape is provided for mounting in handholes 40 and notches 42. The flow blocker 50 is defined by telescopically assembled member 52 and 62 which are biased in opposite directions by pre-loaded spring 64 therein to insure stability against vibration and flow induced loads. The flow blocker 50 fits sungly in notch 42 and handhole 40 and is bolted to the inside of closure plate 74 of handhole 40.

Abstract: A permanent pool seal and neutron shield 30 for providing an effective water barrier over the annular space 28 between a nuclear reactor vessel flange 24 and a surrounding annular ledge 22 includes annular deck sections 32 supported on spaced ribs 46.Flexible membranes 50,52 on the deck section peripheries accommodate relative movement. Openings 42, each with a removable plug structure which includes cover 44 and tapered can 60, provide vessel cavity 14 with ventilation and maintenance access. All cans 60 and similar containers 56 and 59 under the deck structure and flange 24 contain a shielding material 58 in the form of a boron-containing concrete. Supported below the cans is refractory insulating material 54.

Abstract: The device comprises a threaded rod (11a) capable of being screwed into the threaded bore (10') traversing the core (10) and solid, at one of its ends, with a blocking element (11b) the external diameter of which is greater that the diameter of the rod (11a) and which comes into engagement in that end (7) of the casing (4) of the plug (3) opposite the closure base (5) of the plug when the threaded rod (11a) is screwed into the core (10). The blocking element (11b) cooperates with the end of the casing (4) of the plug to achieve the blocking, against rotation and/or translation, of the obturating device (11). The threaded rod (11a) may comprise a transverse orifice in which a braking part is engaged.

Abstract: A replacement heater sleeve for nuclear reactor coolant system pressurizer and method for replacing a damaged original heater nozzle. The original heater and heater nozzle are removed from the pressurizer and the original bore is enlarged. An outer sleeve is installed in the enlarged bore on the same center as the original heater nozzle and is substantially flush with the interior of the pressurizer. The outer sleeve is welded to the pressurizer on its interior and exterior surfaces. An inner sleeve is installed in the inner diameter of the outer sleeve and extends beyond the outer sleeve into the pressurizer. The inner sleeve is welded to the lower end of the outer sleeve and is provided with an inner diameter sized to receive a heater of the same size as that originally installed in the pressurizer. The inner sleeve also maintains the original heater alignment in the pressurizer.

Abstract: The bearing unit of the sealing device of the thermocouple column (40) has an end part (23) in which is provided the bearing area (48) for the thermocouple column (40). This end part has two successive sections in the axial direction, a first section (25) being fastened to the outer end of the follower and a second section (26) being superposed on the first. The first section (25) has a peripheral annular throat (28) and at least three openings (29) traversing the sections (25) in an axial direction so as to open into the peripheral throat (28). The second section has openings (32) in the extension of the openings (29) of the first section. A mounting piece (30) consisting of two half-rings is introduced into the peripheral throat (28) and has tapped openings (35) in the extension of the openings (29, 32) of the first and of the second sections into which screws (36) are introduced and screws into the tapped openings ( 35). A sealing strip (31) is placed between the two sections (25, 26).

Abstract: An auxiliary flexible vacuum seal for preparing a reactor coolant pump for vacuum degasification of the reactor coolant system employs a flexible boot member having a pair of longitudinally-displaced opposite open end portions and a pair of side-by-side longitudinally-extending side portions in the form of flanges defining a split in the boot member along a side thereof and extending between the open end portions for allowing flexing of the boot member between open and closed side configurations to permit its installation and removal on and from the pump. The seal also employs clamping brackets and fasteners for releasably and sealably clamping together the flanges of the boot member at the split to retain the boot member in its closed configuration.

Abstract: A ceramic-based coating is provided on a sealing surface of a sealing assembly component by processing and applying a powder mixture of ceramic particles and metal binder, encasing the coating of powder on the sealing surface by applying a metallic cover thereover, evacuating the atmosphere between the cover and coating, hot isostatic pressing the component and coating, cooling the component and coating, and after cooling thereof removing the cover from the coating.

Abstract: A cylindrical coffer dam assembly is described for use in temporary shielding personnel from nuclear reactor stored internals' radiation. The coffer dam is made up of substantially equal segments small enough to pass through the equipment hatch of the reactor containment building. The segments are pre-fabricated at a factory, transported to the plant, introduced individually into the containment building, and assembled together in sealing relation at the operating floor into a complete coffer dam. The coffer dam is moved to the reactor vessel and connected to the reactor vessel upper flange in sealing relation. The coffer dam can be disconnected, disassembled, removed and re-used at other nuclear reactors.

Abstract: The device for pressure-sealed obturation comprises a flexible tubular casing (22) having an open end along the perimeter of which the casing constitutes an inflatable toric seal (30) and a base (22a) in the form of a glove finger on which there is fixed the end of a shaft (21) disposed at the central part of the casing (22). The shaft (21) passes through the base (22a) of the casing (22) in a sealed manner. The device also comprises a plate (38) for retaining the casing (22) comprising at least two parts articulated to one another as well as retention plate (41) for fixing the retaining plate (38) under the base (22a). Ring shaped elements (43) are retained against the toric seal (30) by an articulated spacing device (47).

Abstract: A system is directed for remotely securing a canopy seal about a broken omega seal site between the control drive mechanism and the adapter tube of a nuclear reactor vessel so as to contain any radioactive leakage therebetween. The system includes a stalk measuring device for initially measuring the diameter of the adapter tube, a split canopy installation fixture which is adjusted according to the measurement detected by the stalk measuring device to position a two-piece canopy seal about the omega seal site, and a robotic weld arm for performing the upper and lower radial welds about the canopy seal as well as C-shaped vertical welds between the two-piece canopy seal.

Abstract: A hollow plug for blocking a heat exchanger tube includes an expansion zone expanded into a frictional connection with the heat exchanger tube. An outer surface in the expansion zone has a first part with a relatively greater surface hardness and a second part with a relatively lesser surface hardness. The first part has a greater surface hardness than the heat exchanger tube. The second part has a lesser surface hardness than the heat exchanger tube. The first part also has a relief pattern.

Abstract: A sealing device for sealing a leak occurring inside a reactor pressure vessel at the vicinity of a weld between a control rod drive (CRD) tube and a surrounding CRD stub tube which communicates with an opening in the wall of the pressure vessel. An inner sealing sleeve of a soft metallic material and with an outer frusto-conical surface is fitted over the tube and the CRD stub tube, and an outer sealing sleeve of a hard metallic material and with an inner frusto-conical surface is fitted over the inner sealing sleeve. On each side of the crack special contact surfaces are formed between the inner sealing sleeve and the tube or the CRD stub tube. As the outer sealing sleeve is pressed in over the inner sealing sleeve, the inner sealing sleeve is pressed by the frusto-conical surfaces, moving against each other, against the tube and the CRD stub tube, thus providing sealing at the contact surfaces.

Abstract: A HP/LP seal arrangement is provided for a guide tube and thimble extending outwardly from the core of a nuclear reactor to a seal table where the guide tube is welded to the seal table to provide a high pressure seal relative thereto. A tubular seal fitting is disposed in alignment with the guide tube with the thimble extending therethrough on the low pressure side of the seal table.A first high pressure seal couples one end of the fitting to an end of the guide tube to prevent leakage from within the guide tube. Inwardly facing threading is disposed adjacent the other and outer end of the seal fitting. A nut is disposed about the thimble and it is provided with outwardly facing threading in mating engagement with the fitting threading.The fitting has a seal seat spaced longitudinally inwardly from the threading and facing the fitting outer end and extending annularly about the inner surface of the fitting.

Abstract: The device comprises a measurement conduit (10) mounted movably in a guide tube connecting the reactor vessel to an instrumentation room which the measurement conduit (10) enters by passing through a sealing nozzle (25). The measurement conduit encloses peripheral sheaths (14) fastened around a central sheath (13). Measuring probes are fastened to the end of cables (16) and mounted movably, each inside a leakproof peripheral sheath (14). The nozzle (25) comprises a leakproof chamber (40). At their ends, each of the peripheral sheaths (14) of the conduit (10) comprises a leakproof passage (50, 50') for the sliding exit of the measurement cable (16) into the chamber (40). Leakproof passge devices (52) for each of the cables (16) are also placed in an exit wall (42) of the chamber (40) of the nozzle (25).

Abstract: A hydro-ball in-core instrumentation system employs detector strings each comprising a wire having radiation sensitive balls affixed diametrically at spaced positions therealong and opposite tip ends of which are transportable by fluid drag through interior passageways through which primary coolant is caused to flow selectively in first and second opposite directions for transporting the detector strings from stored positions in an exterior chamber to inserted positions within the instrumentation thimbles of the fuel rod assemblies of a pressure vessel, and for return. The coolant pressure within the detector passageways is the same as that within the vessel; face contact, disconnectable joints between sections of the interior passageways within the vessel facilitate assembly and disassembly of the vessel for refueling and routine maintenance operations.

Abstract: In methods and devices for removing a blower from a gas-cooled nuclear reactor, removal bells have previously been used which require considerable free space above the blower in the case of vertically extending blower configurations. In order to achieve a lower structural height according to the invention, the periphery of the connection location between the blower housing and the steam generator housing is overlapped by a flange ring attached to the steam generator housing. The blower housing performs a vertical moving maneuver within the range of the height of the flange ring, during which a sealing cover and a transport cover are inserted through a lateral opening in the flange ring. The sealing cover is deposited on the edge of the opening of the steam generator housing and the transport cover is coupled to the bottom region of the blower housing. The blower housing is then removed together with the blower.

Abstract: A plug for sealing the internally threaded circular cylindrical stud holes in the flange of a nuclear reactor vessel during refueling comprises a circular cylindrical body of dense wear resistant polymer, a circular reaction plate axially spaced from one end face of the plug, an annular grommet of elastomer resistant to weak acid held between the reaction plate and the body having an exterior conical surface. A tool extends into the body and applies a torque for turning threads into the internal threads of the stud hole thus drawing the grommet into the stud hole such that it deforms against the interior of the stud hole and the surface of the flange adjacent the stud hole.