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: An ICM housing welded to a wall of a reactor pressure vessel in operation is provided with a molten metal layer containing 4 wt. % or more .delta. ferrite at a portion of an inner peripheral surface thereof which corresponds to a weld. A sleeve made of stainless steel is located at the competent portion of the inner peripheral surface of the ICM housing stainless steel so as to be molten by means of a TIG welding machine to form the molten metal layer. The molten metal layer prevents stress corrosion cracking of the ICM housing.

Abstract: The plug (8) comprises a body in two parts (9, 10) in the form of flanges assembled together so as to be locked against rotation about their common axis and movable in axial translational motion relative to one another. A gasket (11) made of flexible material is inserted between the peripheral parts of the two flanges, and the flanges are axially clamped. The space (12) between the flanges (9, 10) can be evacuated before such clamping.

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: An expendable closure assembly is provided for use (in multiple units) with a lockable pressure vessel cover along its rim, such as of an autoclave. This assembly is suited to variable compressive contact and locking with the vessel lid sealing gasket. The closure assembly consists of a thick walled sleeve insert for retention in the under bores fabricated in the cover periphery and the sleeve is provided with internal threading only. A snap serves as a retainer on the underside of the sleeve, locking it into an under bore retention channel. Finally, a standard elongate externally threaded bolt is sized for mating cooperation with the so positioned sleeve, whereby the location of the bolt shaft in the cover bore hole determines its compressive contact on the underlying gasket.

Abstract: A device for wedging and positioning the upper support plate of the guides of control clusters in relation to a bearing surface linked to the vessel of a pressurized-water nuclear reactor, comprising an upper ring (22) and a lower ring (23) laid onto the cluster guide support plate (8) and the bearing surface (9), respectively, and between which is seated a stack of preloaded elastic washers (24). The device comprises a hollow connecting shank (26) with an axial channel (44) and passing through the two rings, to engage in a bore (20, 21) formed in the support plate or the bearing surface, the lower ring (23) being connectable to the shank, while the upper ring is mounted slidably relative to the lower ring (23) under the effect of the load exerted on the elastic washers.

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: A reactor vessel O-ring spring clip designed to hold the tubular O-ring in the groove of a reactor vessel head flange, especially during head lifting. The spring clip is designed such that the weight of the O-ring acts to increase the friction force between the spring clip and the, typically, threaded hole into which it is inserted. The end of the clip adapted to be inserted through a slot in the tubular O-ring for securement thereto has a circular member thereon which prevents the spring clip from becoming disengaged from the O-ring during head lifting.

Abstract: A radiation reducing door assembly comprises a mounting bracket having hinge means affixed thereto, said hinge means defining different axes of rotation for doors of at least two types, the doors being sized and shaped to overlie at least a portion of the opening with which the assembly is associated. The door assembly also includes means for rotatably coupling the removable doors to the hinge means whereby the mounted door is supported from said bracket and may be pivoted between open and closed positions.

Abstract: The reactor vessel thread protector is a metal cover that is placed over the exposed stud, nut and washer projecting above the closure head to protect the threads from accidental corrosive leakage impingement emitted from mechanical seals on the top of the reactor vessel head. The stud protector includes a drip pan to collect any such fluid being emitted from the reactor vessel. Additionally, the reactor vessel stud thread protector will provide protection from accidental deformation to a stud due to operator maintenance around adjacent studs. The reactor vessel stud thread protector can be in the form of a cylinder which would cover a single stud bolt or a curved box having a rectangular cross-section that would cover a plurality of stud bolts.

Abstract: Disclosed is a reactor internals hold down spring and upper head region cooling passage. The hold down spring utilizes a plurality of stacks of Belleville spring washers to provide spring load and deflection capability to hold down the reactor vessel internals. Each spring assembly includes a generally leak tight means for passing an adjustable coolant flow to the upper reactor vessel head region in order to maintain that region at inlet coolant temperature. The spring assemblies are angularly spaced about a core barrel support flange to cooperate with coolant flow passage formed therein.

Abstract: An annular plate is mounted on and sealed to the spaced apart pressure vessel flange and vessel containment structure of a nuclear reactor to form a leak-proof bottom for a refueling canal for the reactor. The sealing arrangement for the plate establishes redundant seals to each of the flange and containment structure, the seals being pneumatically expandable to enhance the integrity thereof.

Abstract: An improvement in a reactor cavity pool seal which includes a seal plate between the reactor and the cavity wall and an inflatable annular seal, wherein the inflatable seal operates between a seal ring and bearing plate which are elements in addition to the seal plate and cavity wall, thereby eliminating problems of eccentricity and clearance.

Abstract: An annular ring seal for establishing a permanent seal across an annular thermal expansion gap defined between a peripheral wall of a nuclear reactor vessel and a containment wall, which containment wall is spaced apart and surrounds the peripheral wall of the reactor vessel, which collectively define a nuclear reactor containment arrangement. The annular ring seal comprises an annular ring plate having an outer peripheral surface affixed to the containment wall and an inner peripheral surface proximate the reactor vessel; and a flexure member having an annular base plate, which sealingly engages and is affixed to the annular ring plate near the inner peripheral surface thereof, and having a leg which is joined to and extends upwardly from the annular base plate and which is affixed to the peripheral wall of the reaction vessel to thereby seal the annular thermal expansion gap.

Abstract: The invention relates to floating roof tanks for liquids, of the type comprising a cylindrical wall (2), a floating roof (3), and a flexible membrane (4) connecting the periphery of the floating roof to the wall. In accordance with the invention, the tank further includes an overflow duct for providing protection against over-filling when the roof (3) is in its top position. The overflow duct (26) is mounted on the outside of the tank and has an upsidedown U-shaped portion disposed at a height corresponding to a maximum predetermined level for liquid inside the tank when the roof is in its top position. The invention is applicable to the nuclear power industry for storage tanks for topping up the primary circuit of a nuclear reactor with de-gassed water.

Abstract: A pressure tight seal is formed between the confronting planar sealing surfaces on the flanges of a nuclear reactor pressure vessel and its hemispherical head, by a toroidal, crushable tubular seal member which is locked into a flat annular spacer member by a resilient annular member, such as a circular coil spring seated in a V-shaped recess in the inner surface of the flat annular member. The thickness of the flat annular member and the resiliency of the circular coil spring control the deformation of the tubular seal member as the sealing surfaces are drawn toward each other by flange bolts. The flat annular member is provided with axial bores which register with the flange bolts to provide positive positioning of the tubular seal member without the necessity of providing grooves in the confronting planar sealing surfaces.

Abstract: Disclosed is a prestressed concrete pressure vessel having a vessel opening which is closed by a concrete cover. Two separate gaskets are disposed between the cover and the pressure vessel, and bordering on an annular channel. The annular channel is connected with a gas detector by means of a connecting channel. At the same time, the inner area of the cover rises from the pressure vessel at a slight angle. The vertical prestress by which the cover is pressed down is larger than the force acting against it (the internal pressure). Additionally, the horizontal annular prestress of the cover is larger in its upper region than in the lower region. In this manner, a constant seal is combined with means for monitoring the seal.

Abstract: A fast neutron nuclear reactor, in which the main vessel and the slab for sealing said vessel are separately suspended on the upper part of the vessel shaft. An outer ferrule of the slab is directly anchored in the vessel shaft by tie rods and is supported by an annular ring embedded in the concrete. The upper edge of the main vessel is welded beneath the ring, the vessel being supported by a second annular ring embedded in the concrete. The upper faces of the slab and the vessel shaft are consequently at the same level, thereby reducing the heights of the vessel shaft and the safety vessel.

Abstract: A deep beam head for a nuclear reactor and an improved reactor containing such a head where the upper horizontal support plate of a calandria in the reactor forms a sealing plate for the reactor vessel. The sealing plate has a ring member about the upper periphery thereof that is secured to the top of the pressure vessel cylindrical wall and reinforcing members extend across the sealing plate and are welded to the ring, while transverse cross-members extend across the sealing plate and are welded to the reinforcing members. The calandria may be removed from the reactor while attached to the ring member to provide ready access to the reactor internals.

Abstract: A liquid metal cooled nuclear reactor of the kind in which the reactor core is disposed in a pool of liquid metal contained in the inner vessel of a double-walled steel tank supported in a vault having a roof the reactor has the roof supported by a conical support skirt carried by the wall of the vault, a single annular weld securing a main roof member to the skirt, and the conical skirt including a forked part providing inner and outer annular skirt portions from which the inner and outer vessels of the tank are carried respectively.

Abstract: A hydrostatic seal for sealing an annular gap between two flat substantially horizontal coplanar surfaces, and particularly a gap in a nuclear reactor cavity which comprises a generally flat annular plate of a width sufficient to span the gap between the two surfaces, compressible annular sealing rings or gaskets disposed on the bottom surface of the flat annular plate for sealingly engaging the two flat surfaces when a downward force is exerted on the plate, and a plurality of fastening arrangements, distributed along the center line of the plate, for releasably fastening the plate in a position to span the gap and exert a downward force on the plate.

Abstract: Annular slab for closing the vessel of a fast nuclear reactor, comprising at least one downwardly divergent frusto-conical sleeve coaxial with the inner and outer sleeves delimiting the slab, dividing the slab envelope into upper and lower parts respectively filled with concrete incorporating metal reinforcements and with concrete for radiation protection.

Abstract: In combination, a vessel (10), opening means (16) in the vessel, a cover (18), flange means (20) surrounding the opening means, a primary closing means (22, 24) for the cover including a plurality of studs (22) securing the cover onto the vessel, the studs having inner ends threaded into openings (26) in the vessel, nuts (24) cooperating with the outer ends of each of the studs, secondary closing means (32, 34, 38, 40) for the cover including cylindrical clamp means (30, 32) made up of more than one piece, a protruding ledge (34) on the cover over which the clamp means extends, an annular groove (36) in the flange means into which the clamp means extends, a circular retaining ring (38) which surrounds the clamp means, a plurality of threaded openings (42) in the retaining ring, and a plurality of set screws (40) threaded into the openings, so that their ends force the clamp means into tight clamping engagement with the ledge on the cover and the groove in the flange means.

Abstract: The invention relates to a fast neutron nuclear reactor in which the primary pumps and exchangers are suspended on the rigid slab sealing the vessel containing the reactor core.The slab has in its thickness housings of reduced dimensions in which are confined the heads of the exchangers and the primary pumps. The flywheels of the pumps and part of the pipes of the secondary circuits are also contained in the housings. Other housings can be provided in the slab, particularly for the handling of fuels.Application to the improvement of the safety and reliability of fast neutron reactors is taught.

Abstract: A nuclear reactor in which the space between a reactor vessel and a guard vessel disposed outside the reactor vessel is kept in a pressurized, sealed state. The sealed space and the space outside the guard vessel are communicate only through a liquid manometer structure, which is kept sealed with liquid.

Abstract: A closure hold-down system for a prestressed concrete reactor vessel is disclosed which employs a concrete plug having an annular liner thereon and adapted to be received within the upper open end of a cavity in the reactor vessel. A prestressed concrete retaining ring is mounted on the reactor vessel concentric to the plug through a plurality of circumferentially spaced prestressed tendons anchored directly to the reactor vessel, and engages the concrete plug so that pressure forces acting on the plug from within the cavity are transmitted directly from the plug to the prestressed retaining ring through a contact surface therebetween. An omega seal is disposed between the closure plug and a cavity liner to prevent escape of fluid pressure from the cavity.

Abstract: In a nuclear fuel reactor well, storage pool or the like, a lightweight, removable pneumatic action sealing means is disclosed for providing a leak-tight seal between the walls of said well and an access gate. The sealing means comprises a lightweight metallic beam structure removably supported by the gate and arranged between the gate and portions of the adjacent wall. Inflatable sealing members are mounted on the lightweight beam structure and are operable when the gate is in a locked position to expand between the gate and wall, thereby forming a leak-tight seal. The beam structure includes connector flanges so that a hoisting apparatus may be attached to the lightweight structure to lift the entire sealing means from the gate for repair, maintenance or replacement.

Abstract: A pool type nuclear reactor including a number of reactor components located within a vertically extending cavity which is located under a reactor deck arrangement and which is defined by a circumferential cavity wall assembly is disclosed herein. The reactor also includes a reactor vessel separate and distinct from the deck arrangement and the cavity wall assembly for containing the reactor components just recited. This vessel includes a main body located within the cavity and an upper circumferential rim forming a support flange located and interlocked between the deck arrangement and an upper section of the cavity wall assembly whereby to support the vessel body in place.

Abstract: A detachable and leaktight device for closing an orifice of a nuclear reactor vessel during hydraulic pressure testing comprises a body which bears, inside the vessel, on an internal part of the vessel which is resistant to the thrust stresses during the application of pressure, sealing means for producing a seal between the interior and the exterior of the vessel and being mounted on the body, and operating means for fixing and/or demounting the device, the operating means being accessible and operable from outside the vessel.