Abstract: A fluid conduit connector includes a monolithic body having a first opening at a first side and a second opening at a second side. A throughbore extends from the first opening to the second opening. A first array of holes in the first side is positioned around the first opening, each hole of the first array of holes terminating within the body. A second array of holes in the first side is positioned around the first array of holes, each hole of the second array of holes extending through the body to the second side.

Abstract: Provided is a flange for connecting to a complementary flange, and wherein the flange includes a first flange-segment and a second flange-segment, wherein a) the first flange-segment includes a primary bolt circle including an annular arrangement of inclined openings; and a first annular connection face adapted to lie against a complementary second annular connection face of the second flange-segment; and b) the second flange-segment includes on two opposite sides annular connection faces adapted to lie against complementary annular connection faces; a primary aperture circle including an annular arrangement of openings; and a second body section with a secondary bolt circle including an annular arrangement of openings. Also provided is respective flange-segments, a method for manufacturing such flange and a tower construction.

Abstract: A block fitting assembly comprises a first block having a first fastener aperture formed therethrough, a second block having a second fastener aperture formed therethrough in axial alignment with the first fastener aperture, and a fastener extending through the first fastener aperture and the second fastener aperture to couple the first block to the second block. The block fitting assembly includes a thermal expansion compliancy feature in the form of at least one of an inner surface of the second block defining the second fastener aperture including an axially extending non-threaded portion adjacent a threaded portion thereof or the fastener including a necked portion having a smaller outer diameter than a minor thread diameter of a threaded portion of the fastener.

Abstract: A catalytic reactor comprises a load distributor assembly to evenly transfer a load from equipment (internals) to a reactor support ring or support structure fixed within the reactor shell, thereby maximizing the possible load to be applied to the support ring or support structure without any hot-work modifications and without exceeding the allowable tensions/stress.

Abstract: An emergency core cooling system removes decay heat generated by a reactor core of a reactor system. A reactor vessel uses water as a coolant. A containment structure surrounds the reactor system. A reactor cavity surrounds the reactor vessel. A first cavity pipe extends into the reactor vessel and provides a recirculation loop of cooling water by discharging vapor generated in the reactor vessel and supplying condensed water collected in the reactor cavity in an opposite direction.

Abstract: A nuclear steam supply system includes an elongated reactor vessel having an internal cavity with a central axis, a reactor core having nuclear fuel disposed within the internal cavity, and a steam generating vessel having at least one heat exchanger section, the steam generating vessel being fluidicly coupled to the reactor vessel. The reactor vessel includes a shell having an upper flange portion and a head having a head flange portion. The upper flange portion is coupled to the head flange portion, wherein the upper flange portion extends into the internal cavity, and the head flange portion extends outward from the internal cavity.

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: A pressure vessel, including: a body portion; and an inclined nozzle projecting from the body portion along an axis inclined relative to an inner surface of the body portion, wherein: a through hole of a circular section is formed through both the body portion and the inclined nozzle. At an intersecting portion between the inner surface of the body portion and a surface surrounding the through hole, there are formed round portions. The radius of each of the round portions at two positions in a major axis direction is smaller than the radius of each of round portions.

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 method including placing around the shoulder of the lid a ring-shaped gasket formed by a metal strip maintained on the vertical wall of the shoulder by self-maintaining members firmly attached to the strip, placing the lid bearing the ring-shaped gasket above the vessel by positioning it at a determined height, carrying out a cleanliness inspection of the gasket plane, lowering and laying the lid on the vessel so that the end side edges of the strip will come into contact with a horizontal wall of the lid and of the vessel flange respectively and attaching this lid on the vessel.

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: A method including placing around the shoulder of the lid a ring-shaped gasket formed by a metal strip maintained on the vertical wall of the shoulder by self-maintaining members firmly attached to the strip, placing the lid bearing the ring-shaped gasket above the vessel by positioning it at a determined height, carrying out a cleanliness inspection of the gasket plane, lowering and laying the lid on the vessel so that the end side edges of the strip will come into contact with a horizontal wall of the lid and of the vessel flange respectively and attaching this lid on the vessel.

Abstract: The invention relates to a method for the water filling and air blow-off of a main primary circuit (1) of a nuclear unit after stopping the same, said main primary circuit (1) including a tank (2) located in a pool of a reactor building (4), primary pumps (5), at least one steam generator (6) including a plurality of steam generating tubes (7) located above the level of the tank (2), and a pressuriser (8).

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: A covering element for a reactor core of a nuclear installation provides a secure and tight closure of the reactor core in an operating state and at the same time being simple and cost effective to produce. The covering element is easily disassemblable during maintenance or loading processes and provides good possibilities for intervention in the reactor core. For this purpose, the covering element has a closure head and a separate support ring. The support ring is joined form-lockingly and/or force-lockingly to the closure head.

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: A sealing device (10) comprising a first sealing element (12) having a housing (18) with an internal chamber (26) therein and a second sealing element (14) having a shaft (34). When the first (12) and second sealing elements (14) are connected, the shaft (34) of the second sealing element (14) extends into the internal chamber (26) of the first sealing element (12) through an opening in its housing. According to an important aspect of the invention, the first sealing element (12) comprises a pressure sensor (46) connected to the internal chamber (26) for sensing a pressure in the internal chamber (26); and a transmitter (48) for receiving a signal indicative of the pressure in the internal chamber and for transmitting the signal to a monitoring station.

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: A reactor pressure vessel supports the flanges of a core barrel assembly and an upper support plate. These flanges have aligned holes for diverting inlet coolant water to the vessel head for cooling the head. The aligned holes have different cross-sectional areas for controlling unexpected backflow of coolant water from the vessel head around the periphery of the upper support plate.

Abstract: A reactor pressure vessel supports the flanges of a core barrel assembly and an upper support plate. These flanges have aligned holes for diverting inlet coolant water to the vessel head for cooling the head. The aligned holes have different cross-sectional areas for controlling unexpected backflow of coolant water from the vessel head around the periphery of the upper support plate.

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: A reactor pressure vessel supports the flanges of a core barrel assembly and an upper support plate. These flanges have aligned holes for diverting inlet coolant water to the vessel head for cooling the head. The aligned holes have different cross-sectional areas for controlling unexpected backflow of coolant water from the vessel head around the periphery of the upper support plate.

Abstract: A device for sealing a tube in an opening which is located in a component. The tube is in particular a lance shaft and the component is in particular a nozzle connected to a cover of a reactor pressure vessel. A pressure element is in operative connection with the tube. As a result, the tube is pressed against the component. Provision is made for the pressure element to be driven hydraulically.

Abstract: The present invention is used to reduce thermal load itself, being the cause to generate stress, which develops near liquid surface in a nuclear reactor wall and to contribute to further improvement of safety. A partition member (5) is arranged above a coolant liquid surface (9) in an annulus space (3) between a reactor vessel (1) and a guard vessel (2), a low-temperature gas is circulated through the annulus space above the partition member to cool down, the gas is circulated through the annulus space from under the coolant liquid surface to the partition member, and the high-temperature gas heated under the coolant liquid surface is used to raise the temperature above the coolant liquid surface.

Abstract: A seal arrangement for providing a seal between a nuclear reactor in-core instrument housing and an instrument contained within the housing includes a lower seal assembly surrounding an outer portion of the in-core instrument housing, an upper seal assembly surrounding an outer portion of the in-core instrument, a seal housing enclosing the lower and upper seal assemblies, and lower and upper compression assemblies positioned on respective ends of the seal housing. The compression assemblies each include a drive nut and a compression collar. The compression collars engage and apply an axial load on the seal assemblies to maintain a reliable seal between the seal housing and the outer portion of the in-core instrument housing, and between the seal housing and the outer portion of the in-core instrument.

Abstract: A nuclear power plant comprising a casing which encloses a primary space, a reactor vessel arranged in the primary space, and a reactor core provided in the reactor vessel. The plant further comprises an upper space provided above the casing. The reactor core is separated from the upper space by means of an openable cover arrangement. The casing is designed in such a manner that the primary space is completely closed against the environment to at least the level corresponding to the most highly located part of the reactor core. The upper space is arranged to house a volume of a liquid sufficiently large to permit the filling of the primary space with the liquid to a level located above the most highly located part of the reactor core.

Abstract: A method of temporarily sealing a reactor pressure vessel during an outage permits the water level in the vessel to be drawn down to a level which enables the interior surfaces of associated structures and equipment in the primary coolant loop to be inspected while dry when the vessel is submerged in a pool of water. A reactor pressure vessel internals lifting rig is used to position a temporary reactor pressure vessel head having an elliptical shaped dome with a circumferential flange retaining a pair of spaced apart, circumferential seal rings onto a reactor pressure vessel circumferential flange without marking or damaging the reactor pressure vessel flange.

Abstract: A canopy seal clamp assembly (40) for stopping leaking in a canopy seal weld (42) located between a nuclear reactor vessel nozzle (30) and an elongated housing (24) includes an upper plate (44) having a central aperture (50) and an inner flange (52) spaced apart from a lower plate (60) having a central aperture (66) and an inner flange (68), a seal carrier (70) located adjacent the lower plate carriers a seal (72) for contacting an outer surface of a leaking weld (42) and connector (56) between the upper and lower plate maintain a compressive load to tightly seal the leaking weld and the compressive load tends to close and arrest further crack propagation in the weld. A method for repairing a weld is also described.

Abstract: A top mount canopy seal mechanical clamp assembly 20 for repair of a leaking canopy seal weld 16 between a nuclear reactor head penetration nozzle 12 and a mating part 14 has an annular housing 24 with insert support halves 28 and 30 for surrounding the nozzle. A top plate 34 is urged toward the support halves and housing by Belleville washers mounted on cap screws 42 threaded in bores 44 of the housing. A flexible graphite seal annulus 22 is compressed by the clamping action against the canopy seal weld 16 to create a flexible graphite leak stopping seal at the weld.

Abstract: A tool fixture device for positioning tools to repair defects adjacent to the sealing grooves in a pressure vessel head. The device includes a two pair of parallel, spaced apart, arcuate segments adapted to fit into one of the sealing grooves. A support plate is attached to the first and the second pair of parallel, spaced apart, arcuate segments. The fixture includes a plurality of threaded rods for expanding the ends of the parallel arcuate segments to engage the inside walls of one of the grooves to hold the fixture in place. In the preferred embodiment, a tool positioner is adapted to be attached to the support plate for positioning a repair tool to permit the repair tool to be used to repair defects adjacent to the sealing grooves. The tool positioner includes a planar table and a tool jig attached to the planar table for receiving the repair tool.

Abstract: A bottom head dome assembly which includes, in one embodiment, a bottom head dome and a liner configured to be positioned proximate the bottom head dome is described. The bottom head dome has a plurality of openings extending therethrough. The liner also has a plurality of openings extending therethrough, and each liner opening aligns with a respective bottom head dome opening. A seal is formed, such as by welding, between the liner and the bottom head dome to resist entry of water between the liner and the bottom head dome at the edge of the liner. In the one embodiment, a plurality of stub tubes are secured to the liner. Each stub tube has a bore extending therethrough, and each stub tube bore is coaxially aligned with a respective liner opening. A seat portion is formed by each liner opening for receiving a portion of the respective stub tube. The assembly also includes a plurality of support shims positioned between the bottom head dome and the liner for supporting the liner.

Abstract: A joint for interfacing a steel head closure and a steel-lined prestressed concrete reactor vessel (PCRV). The steel head closure is bolted to a thick steel annular plate and a thermal barrier is arranged in a volume bounded by the head ring, the liner and the concrete of the PCRV wall. The thermal barrier is made of zirconia sand or other material having a low thermal conductivity, a high bulk modulus equal to that of concrete, and a low shear modulus. Differential thermal expansion of the vessel head closure and PCRV is accommodated by a flexible connection of the PCRV liner to the inner periphery of the head ring. In the alternative, the steel head closure is interfaced to the top of the PCRV via a sliding joint or a thermal stress relief ring. In accordance with a further alternative, thermal stresses in the steel vessel head closure are mitigated by reducing the temperature of the head closure by installing thermal insulation on all internal surfaces thereof.

Abstract: A nuclear containment arrangement has a permanent pool cavity seal extending across an annular gap between a reactor pressure vessel and a refueling pool wall to provide a water tight seal therebetween. A seal plate has a support ring with a cylindrical section weldedly connected to an outer seal ring on an embedded ring. A J-shaped flexible ring attached to the seal plate allows axial and radial movement of the reactor vessel during thermal expansion and contraction. The inner portion of the seal plate overhangs the J-shaped flexible ring thereby to protect it from damage resulting from an object dropped thereon. Cooperating access holes and access hole covers in the seal plate provide access to the refueling pool cavity. Support arms underneath the seal plate are provided. Each support arm may have leveling screws to adjust the level of the seal plate.

Abstract: An omega seal (32) between a housing (24) having a circumferential omega lip (38) including a free end, and a reactor vessel nozzle (22) having a complimentary omega lip (40) including a free end. A semi-rigid, annular seat member (60) is placed within one of the lips, and the housing is positioned in vertical alignment with the nozzle so that the free end of the housing lip and the free end of the nozzle lip are juxtaposed, thereby forming an omega structure having a cavity (44) occupied by the seat member, a gap (42) between the free ends of the lips, and an outer surface (47,49) on either side of the gap. A semi-rigid ring (46) is positioned in conforming relation to the outside surface of the omega structure. A compressive force is applied and maintained on the exterior of the seal ring, thereby extruding a portion of the ring into the gap.

Abstract: A fluid tight mechanical clamp for creating a compressed graphite seal between a resistance temperature detector nozzle and a NSSS piping hot or cold leg pipe is provided which includes a split graphite seal ring, a peripheral seal back-up ring, a split load sleeve to axially compress and radially expand the split seal ring, a reactor plate and load ring with bolts to drive the load sleeve and compress the seal, and a blowout retainer to prevent the nozzle from blowing out of its seat in the pipe wall in the event of a weld failure. Extensive welding procedures to repair nozzle leaks are thus eliminated.

Abstract: A system for inspection and mending in a reactor vessel of a nuclear reactor comprises a track mechanism, support mechanisms for supporting the track mechanism, an inspection apparatus traveling on the track mechanism, at least one mending apparatus traveling on the track mechanism, a setting mechanism for lowering all the above-described mechanisms and apparatus in the reactor vessel, each of which is composed so as to pass through a hole of an upper grid of a reactor, and an installing mechanism for positioning the support mechanisms fixed with two of the upper grid, a core support plate and internal structures below the core support plate and the track mechanism at the inside of the reactor vessel by remote control and for attaching the inspection apparatus and the mending apparatus to the same track mechanism by remote control.

Abstract: In order to reduce the time and difficulty of disassembling a seal arrangement in a cramped radioactive environment, a nozzle assembly hub is provided with a step bore which receives a seal arrangement, a compression collar, and a retaining nut which presses the seal arrangement into engagement with an inner wall portion of the hub and an outer wall portion of an ICI (in-core instrument) seal plug assembly. The ICI units remain connected to the seal plug assembly during normal disassembly operations. In this manner, the nozzle assembly may be disassembled by merely removing the retaining nut, compression collar, and seal arrangement and lifting the reactor head, along with the nozzle assembly, over the ICI units. The compression collar extends outside the retaining nut such that the collar can be engaged and compressed by an hydraulic loading tool while threading the retaining nut onto the hub.

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 cylindrical section and a lower flexible corrugated or arcuate shaped section which accommodates radial, axial and rotational movements of the vessel, and reduces joint stress.

Abstract: Extrusion-resistant seal assembly for sealing a gap defined between a first structure spaced-apart from a second structure, which first structure and second structure may be an annular first flange and an annular second flange belonging to an instrumentation column of the kind typically found penetrating nuclear reactor pressure vessels. The seal assembly includes an annular retainer disposed in a gap defined between the first flange and the second flange, the first flange and the second flange capable of being moved into close proximity to reduce the gap therebetween. The retainer includes a first surface thereon having a first recess extending therearound. The retainer also has a second surface thereon having a second recess extending therearound. An annular first gasket is retained in the first recess and an annular second gasket is retained in the second recess.

Abstract: The equipment comprises a bottom plate formed with outlet openings for the coolant, a top plate, spacer rods interconnecting the plates, and cluster guides for guiding control clusters. At least some of the guides have respective top lengths that project above the top plate and bottom lengths that extend between the plates. Each bottom length includes a base bearing against a frustoconical seat secured to the bottom plate, and it is subjected to the force of resilient means. Together, the lengths of each guide constitute a one-piece cartridge suitable for insertion in a corresponding column. The guide also includes a cap for receiving the top length, which cap is fixed to the top plate against which the resilient means bear.

Abstract: A method of refueling a nuclear reactor whereby the drive mechanism is disengaged and removed by activating a jacking mechanism that raises the closure head. The area between the barrier plate and closure head is exhausted through the closure head penetrations. The closure head, upper drive mechanism, and bellows seal are lifted away and transported to a safe area. The barrier plate acts as the primary boundary and each drive and control rod penetration has an elastomer seal preventing excessive tritium gases from escaping. The individual instrumentation plugs are disengaged allowing the corresponding fuel assembly to be sealed and replaced.

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: Disclosed is a means for increasing coolant flow through the areas adjacent to where the removable top head closure is bolted to the body of pressurized water nuclear reactor. A circumferential plenum for coolant is provided between the upper flange of the core barrel, the inner wall of the pressure vessel body and the upper circular support plate and providing a plurality of orifices for coolant in the upper flange of the core barrel and the upper circular support plate whereby a coolant may be circulated through the core barrel flange, the circumferential plenum and the upper support plate and into the space enclosed by the removable top closure head.

Abstract: In order to reduce the time and difficulty of disassembling a seal arrangement which includes a Grayloc flange, in a cramped radioactive environment, the Grayloc hub is modified to include a step bore which receives a seal arrangement and a retaining nut which presses the seal into engagement with an inner wall portion of the hub and outer wall portion of an ICI (in core instrument) supporting column. A loading ring is threaded onto a portion of the column. Bolts associated with the ring are screwed down onto a belleville washer which is disposed between the loading ring and the top of the retaining nut for maintaining a desired amount of load on the seals irrespective of thermal variations.

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: A device 20 for cleaning threaded studs 14 securing the dome-shaped head of a nuclear reactor pressure vessel to the vessel body 10 comprises a cylindrical brush holder 24 rotatably carried in a housing 22. An annular steel wire brush 28, disposed on the inner surface of the brush holder 24, is adapted to fit over and engage the threaded portion 14a of a stud 14. An electric motor 26 mounted on the housing 22 rotates the brush holder 24 as it is lowered onto an upstanding stud 14. A vacuum source connected to the housing 22 captures any particulate matter removed from the stud 14.

Abstract: A head for closing a nuclear reactor pressure vessel shell includes an arcuate dome having an integral head flange which includes a mating surface for sealingly mating with the shell upon assembly therewith. The head flange includes an internal passage extending therethrough with a first port being disposed on the head mating surface. A vent line includes a proximal end disposed in flow communication with the head internal passage, and a distal end disposed in flow communication with the inside of the dome for channeling a fluid therethrough. The vent line is fixedly joined to the dome and is carried therewith when the head is assembled to and disassembled from the shell.

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.