Abstract: The invention relates to a device for thermal protection of a component of a fast-neutron nuclear reactor consisting of at least one shell (10, 11) of a diameter smaller than the diameter of the passage (2) for the component (4) but greater than the diameter of the component (4). The length of the shell (10, 11) fixed under the flange (5) of the component (4) is greater than the slab thickness (1). Circulation of blanket gas (13) is established in the annular space (7) between the component (4) and the passage (2).The invention applies in particular to nuclear reactors cooled with liquid sodium whose upper level is under an argon blanket.

Abstract: A nuclear reactor is equipped with a cooling water circulation system which includes a water-feed conduit and a drain conduit to circulate the cooling water to and from a pressure vessel which surrounds a reactor core, the cooling water having a free liquid level maintained above the reactor core. The drain conduit is inserted in the pressure vessel from the upper side toward the lower side relative to the free liquid level. A double tube consisting of an inner tube and an outer tube maintaining a gap therebetween is formed in the end portion of the drain conduit. The inner tube and outer tube being continuous with the drain conduit, the opening at the lower end of the inner tube is located below said free liquid level but above the reactor core. The opening at the upper end of the outer tube is located above the free liquid level. The opening at the lower end of said outer tube is located below the reactor core.

Abstract: Device for the homogeneous mixing of liquids flowing at different temperatures comprising a member connected to an inlet tube and to an outlet tube of a main circuit in which circulates a hot liquid, a cylindrical inlet of the member being connected to a secondary tube of a secondary circuit in which circulates a cold liquid, a cylindrical circuit sealingly fixed to the member on the outlet side thereof and having openings on the inlet tube side, wherein (1) an envelope formed, as from the inlet tube, by a cylindrical part, a frustum-shaped part and a cylinder surrounds the cylindrical pipe providing an annular space with the latter over part thereof located on the side of the inlet tube and having the said openings; (2) the envelope forms a first annular channel with the member; (3) a connecting tube connected to the secondary tube and to the cylinder forms, with a cylindrical inlet of the member, a second annular channel linked to the first annular channel; and (4) the cylindrical pipe has a series of holes

Abstract: A pipework junction (10, 11) has internal insulation to limit the effect of thermal shock in the form of a two part (14, 15) internal sleeve in which the parts of the sleeve are joined (34) and are, for the most part of their external surfaces, spaced from the junction by a small clearance (20) adequate to ensure that they do not lock to the junction when subjected to thermal shock. Piston rings (62) may be provided to restrain flow along the small clearance and the sleeve may be stabilized in the junction by having an expanded part (63) engaging a recess (64), which also serves to restrain flow along the small clearance.

Abstract: A self-supporting pipe rupture and whip restraint system (10) for a process fluid pipe (12) of a nuclear reactor steam generator pressure vessel (14) includes a guard pipe (26) concentrically disposed about the process pipe (12) so as to entirely encase the process pipe (12) from the pressure vessel nozzle 18 to a terminal end fitting component (36) disposed exteriorly of the reactor facility building wall (32), the guard pipe (26) being integrally fixed to the process pipe (12) through means of the nozzle (18) and the component (36). Under postulated rupture conditions of the process pipe (12), pipe whipping of the process pipe (12) is restrained by the guard pipe (26), and the process fluid effluent from the process pipe (12) is contained within the guard pipe (26). Leak detection apparatus (50) is operatively associated with the annular space (30) defined between the process pipe (12) and the guard pipe (26) so as to detect ruptures or fractures within either the process pipe (12) or the guard pipe (26).

Abstract: The invention is directed to an arrangement for centering conduits to facilitate coupling an end flange of a stationary conduit with an end flange of a conduit section removable in the vertical direction. The conduits interconnect materials processing apparatus in a large-area cell for reprocessing irradiated nuclear fuel. The interface separating the connected flanges is in a vertical plane. The joining of the stationary end flange to the end flange of the movable conduit section is carried out by remote handling and the operator performs the connecting process with the aid of a television monitor. To enable the process of coupling the flanges to be carried out quickly, safely, and in a simple manner, the arrangement of the invention includes an upwardly projecting vertical centering key mounted on the stationary pipe conduit. A V-shaped guide defining mutually adjacent centering surfaces is mounted on the removable conduit section.

Abstract: Nuclear reactor cooled by a liquid metal comprising a main vessel sealed by a sealing slab, said vessel containing liquid metal overhung by a covering of inert gas, the reactor core being placed in a primary vessel integrated into the main vessel in such a way that the primary vessel at the outlet from the core constitutes a hot collector for the liquid metal and the space defined between the main vessel and the primary vessel constitutes a cold collector for the liquid metal, at least one heat exchanger supplied by the liquid metal contained in the hot collector under the action of at least primary pumps located in the main vessel, wherein the exchanger is positioned outside the main vessel at a level above that of the sealing slab and communicates with the hot collector by at least one intake pipe and with the cold collector by at least one outlet pipe, it being possible to empty the exchanger and pipes into the main vessel by gravity, the upper part of each exchanger being filled with the inert gas coverin

Abstract: A reactor cavity surrounding a reactor coolant inlet or outlet pipe is designed to reduce pressurization of the cavity in the event of a LOCA pipe break therein.

Abstract: A passage through a reinforced concrete pressure vessel is provided, wherein the tolerance ranges required for the fastening of the components in the passage may be produced safely and without excessive expenditures. This is achieved by an arrangement including a lining having a first, outer tube resting against the concrete and a second tube arranged within the first tube.

Abstract: A single guide tube and tube sheet tube, as an upper extension, carries a nuclear control rod in storage, poised for downward insertion into the guide tube. An inner tube, termed a bypass tube, is mounted within the cylindrical tube sheet tube and fitted closely about the control rod. Mounting connections between the upper and lower ends of the bypass tube and the tube sheet tube are provided to route the coolant in control of the rod vibration.

Abstract: A high-temperature nuclear power plant, includes a reactor, an inner vessel enclosing the reactor, an outer reactor pressure vessel disposed outside the inner vessel, a stub integral with the outer vessel, and a hot gas pipeline disposed in the stub, the improvement comprises a screw connection being releasable from outside the outer vessel for fastening the hot gas pipeline to the inner vessel, and a device connected to the hot gas pipeline for applying a force to the hot gas pipeline in a direction tending to separate the hot gas pipeline from the inner vessel.

Abstract: Disclosed is a remotely operable releasable sealing coupling which provides fluid-tight joinder of upper and a lower conduit sections. Each conduit section has a concave conical sealing surface adjacent its end portion. A tubular sleeve having convex spherical ends is inserted between the conduit ends to form line contact with the concave conical end portions. An inwardly projecting lip located at one end of the sleeve cooperates with a retaining collar formed on the upper pipe end to provide swivel capture for the sleeve. The upper conduit section also includes a tapered lower end portion which engages the inside surface of the sleeve to limit misalignment of the connected conduit sections.

Abstract: A junction device between the delivery duct of a primary pump and a duct joined to the core support of a liquid metal cooled fast neutron nuclear reactor comprises a frusto-conical sleeve (6) widening out towards the inlet (2) of the duct joined to the core support, a connecting member (7) joined to the sleeve (6), a sealing device (18) interposed between the outlet end of the sleeve (6) and the inlet (2) of the duct joined to the core support, and an elastic means (6) interposed between the outlet end of the sleeve (6) and a support member joined to the core support. In its central portion the connecting member (7) carries the movable portion (14) of an articulated connection element the fixed portion (16) of which is carried by the pump. On its periphery this member (7) is connected sealingly and articulatedly to the delivery duct of the pump at the level of a spherical surface (9).

Abstract: Heat retarding closure system for partitions having pressure relief openings formed therein especially in nuclear reactor buildings where main coolant nozzles of a reactor pressure vessel penetrate a biological shield, including lightweight construction closure elements having a side facing the reactor and anchors for holding the closure elements, the closure elements being pushable out of the anchors by an overpressure in a given pressure difference direction on the reactor side, and an outer sealing blowout skin, the closure elements being in the form of heat-retarding cassette inserts having a front surface with a peripheral shearing edge formed thereon resting against the blowout skin, and the blowout skin having a given thickness in the given pressure difference direction enabling the cassette insert to shear off the blowout skin and be pushed out of the anchors when a given pressure difference is at least reached.

Abstract: The invention pertains to a containment system for a nuclear power plant which provides protection in the event of a loss of coolant accident or other malfunctions wherein the stored energy within the components of the system is contained and absorbed by the use of a plurality of coolant reservoirs capable of absorbing steam and supplying coolant to the reactor coolant system and feedwater to the secondary systems. The system includes a plurality of steam generators which may selectively be employed as an energy source during cooldown, and the design of the reservoirs provides high initial energy absorption as well as extended energy dissipation during cooldown.

Abstract: The present invention relates to a device providing anti-seismic support for an apparatus immersed in the bath of liquid alkali metal surrounding a fast neutron nuclear reactor, and abutting by a flange on a slab traversed by the apparatus and resistant to the load that it constitutes, wherein the flange for supporting the apparatus is connected to a sleeve for elastically taking up the horizontal displacements of its top part, independently of an inner envelope of the apparatus and on which a framework for supporting the apparatus whose bottom part is connected to the inner envelope, is fixed at a level determined as a function of the most dangerous earth tremor frequencies.

Abstract: Nuclear boiler comprising a vessel sealed in its upper part by a removable cover, a basket-shaped member carrying the reactor core and separating the vessel into a hot inner area and a cold outer area, at least one steam generator positioned within the vessel and comprising a tightly sealed enclosure and a tube plate separating the enclosure into a primary part or water box and a secondary part, the tube plate carrying U-tubes, whose ends issue into a cold area and a hot area of the water box, defined by an inner structure, two linear, coaxial tubes defining an inner pipe and an annular outer pipe respectively connecting the hot areas and cold areas of the vessel and the water box, wherein a removable safety sleeve, whose wall is designed to resist the pressure in the primary circuit, is arranged coaxially within the outer annular pipe and defines with the latter a calibrated clearance making it possible to limit to a given value the leakage flow if the outer tube fractures.

Abstract: An improved design for shielding the component parts of a gas turbine power plant from radiation in a gas transport conduit is disclosed. The radiation shield and shielded gas conduit utilize a shielding arrangement comprising a displacement body arranged centrally within the conduit and a shielding annulus surrounding the displacement body. A shielding device provides for a first annular flow path for reactor cooling gas between the displacement body and shielding annulus and a second annular flow path for reactor cooling gas between the shielding annulus and the conduit housing. The shielding device provides protection against radiation without significantly disrupting the flow of the cooling gas in the conduits.

Abstract: The present invention relates to a nuclear boiler comprising a vessel whose top is closed by a dismountable cover, a cage bearing the core of the reactor and separating the vessel into an inner hot zone and an outer cold zone, at least one steam generator disposed outside the vessel and comprising a tight enclosure, a tube plate, separating the enclosure into a primary part, or water box, and a secondary part, and bearing U-shaped tubes whose ends open into two concentric zones of the water box separated by an internal structure, at least one hot connecting pipe and one cold connecting pipe respectively connecting the hot zone and the cold zone of the vessel to each of the concentric zones of the water box, wherein the tube plate, the tubes and the secondary part of the enclosure of the steam generator define a sub-assembly dismountable from the primary part of the enclosure, the hot connecting pipe being dismountably mounted between the cage and the internal structure of the water box, this strucutre itself

Abstract: Fast neutron nuclear reactor cooled by a liquid metal, comprising a main vessel sealed by an upper slab and within said main vessel at least one heat exchanger between the said liquid metal and a second fluid, at least one pump for circulating the liquid metal, a cylindrical inner vessel with a vertical axis and placed on flooring resting on the bottom of the main vessel, the inner vessel containing the reactor core which rests on a support bearing against the bottom of the main vessel by means of the said flooring, the liquid metal circulating from bottom to top through the reactor core, wherein the said inner vessel incorporates an internal baffle which revolves about the vertical axis of the inner vessel, said baffle comprising an upper cylindrical part adjacent to the inner vessel and arranged above the core, and a lower cylindrical part surrounding the core and having a smaller diameter than the upper part, said lower part being connected to the upper part by a frustum-shaped part, whereby the baffle con