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: Steam generators are used in pressurized water-cooled nuclear reactors for generating steam which issues from the generator through a large bore steam outlet. Heat-exchange tubes through which feed water flows are surrounded by hot cooling water from the reactor. The tubes must be capable of being inspected and repaired. To simplify inspection and repair, the tubes are U-shaped and each end of each tube is connected upwardly to a tube plate in the steam generator, whereby each end of each tube can be reached in a simple manner through an outgoing steam outlet.

Abstract: A core of a light water boiling reactor comprises a plurality of vertical fuel assemblies (10) and a plurality of control rods, each control rod comprising four vertical blades arranged in a cruciform. The control rods are arranged with each one of their blades between two fuel assemblies located in the same row, such that each control rod together with four fuel assemblies arranged around the blades of the control rod form a unit, the control rod unit (30, 30-o), having an at least substantially square cross-section. The control rod units are arranged in a symmetrical lattice with each control rod unit included in two rows of control rod units perpendicular to each other.

Abstract: To be able to design a smaller unit of a nuclear power plant, the containment of pre-stressed concrete has been made in the form of a bottle. In this way, a "conventional" pump with a shaft packing and a dry motor can be used by locating the motor, for driving the pump for circulation of the process water, in a sealed, detachably connected steel dome (16). When being removed, the detachably connected steel dome (16) provides access to the riser (1) for refuelling.

Abstract: The invention relates to a fuel assembly for a nuclear reactor comprising a bundle of longitudinal fuel rods which are insertable into the fuel assembly and held together by spacers (1), consisting of cells, arranged along the bundle. The wall of the fuel assembly towards the bundle of fuel rods is provided with a number of first locking members (5) arranged in the longitudial direction of the wall, and the spacers (1) are provided with a second locking member. The second locking member comprises at least two interconnected rods (3), one rod consisting of material having a low coefficient of thermal expansion and the other rod consisting of material having a high coefficient of thermal expansion. These rods have been adapted, in dependence on the temperature in the reactor in operation, to bring the second locking member into engagement with the first locking members (5) and to release the same when the reactor is shutdown.

Abstract: A bimetallic spacer for supporting fuel rods in position in a nuclear reactor fuel assembly substantially comprises inner and outer structural elements of a first metallic material and spring elements of a second metallic material. The structural and spring elements together define a lattice, the interstices of which receive the individual fuel rods. The structural elements and spring elements in the spacer are connected together by forming the structural elements with openings and fitting the ends of the spring elements in the openings. At one end of the opening in the structural element, two slots can be provided for forming a tongue-shaped member which is moved aside to make space for the spring element and then moves back when the end of the spring element is in position, thus preventing a possible vertical return movement of the end of the spring element.

Abstract: A fuel assembly for a boiling water reactor is provided with at least one vertical channel for a by-pass flow through the fuel assembly. The channel is supplied with water through a vertical supply tube surrounded by the base of the assembly, the supply tube being arranged with its lower end in the vicinity of the lower end of the base.

Abstract: A gripping mechanism for gripping a retraction cone attached to a workpiece includes an outer shroud formed of an outer tubular part and an outer funnel-shaped part; a gripping device which is axially movable within the outer shroud, the gripping device including a tubular sleeve which has wings axially movable with axial slots in the outer tubular part and a plurality of finger elements with hook-shaped ends attached to the wings; an operating device which includes an independently rotatable sleeve threadingly engaged in the tubular sleeve and an inner funnel which is attached to the outer funnel-shaped part and which includes control slots for the finger elements; and a motor for rotating the rotatable sleeve so as to either axially move the tubular sleeve within the outer shroud such that the finger elements move towards the retraction cone for gripping the retraction cone or, after having gripped the retraction cone, in an opposite direction to position the retraction cone within the inner funnel.

Abstract: A nuclear fuel assembly for a boiling reactor comprises a plurality of fuel rods arranged in four sub-bundles surrounded by a fuel channel of substantially square cross-section. A vertical channel-formed support member for the passage of water, separates the sub-bundles of fuel rods. By arranging each sub-bundle with a reduced corner portion by not locating a fuel rod in that corner of the sub-bundle towards the center of the fuel assembly, the sub-bundles can be located in a separating channel-formed support member with an enlarged central channel. The enlarged central channel makes it possible to contain a larger quantity of non-boiling water in the central part of the fuel assembly, which results in better neutron moderation in the central part of the fuel assembly.

Abstract: A layer of small-sized particles of an organic ion exchange resin is applied to a support matrix, permeable to liquid, of a filter element (7) which is arranged in a chamber (5) in an ion-exchange filter (1) for filtering of liquids containing radioactive constituents. The filter and a mixer (11), consisting of a tube with a number of stationary mixing elements arranged one after the other in the longitudinal direction of the tube, are arranged in a circulation system (10) for water. The mixing elements successively divide up a material flow, supplied at the inlet end of the mixer, into a number of sub-flows containing different parts of the original material flow and the sub-flows are reunited, before they reach the outlet end of the tube. Suspended ion-exchange resin (13a, 16a) is supplied to the inlet end (11a) of the mixer for the circulating water while the water is being circulated in the circulation system.

Abstract: The present invention relates to a method for replacing an insert unit included in an insert valve assembly belonging to a subsea production system for gas and oil. In carrying out the method, a manipulator (1) is brought by means of a sheave (2), a hoisting cable (3) and guide wires (4, 5) down to a predetermined location on the bottom of the sea. The manipulator comprises a telescopic arm (15, 16) which is then moved towards and fixed by means of a hook (20) and a lug (21) to a valve tree (17) which supports a valve (22), the insert unit (26) of which is to be unscrewed from the respective valve housing and be replaced. A carriage (18) located in the manipulator and comprising retracting, aligning and fixing devices (32, 33, 34) is brought with the aid of the telescopic arm and a rail, located on the top side of the carriage, towards the valve tree and is fixed to retraction cones (35, 36, 37) mounted on the valve tree.

Abstract: A rotating drum pump having a plurality of fluid driven pistons includes a pump housing with an enclosed rotating drum, and connection openings for a supplied and discharged driving fluid and for a supplied and discharged pump flow located in end walls of the housing. The drum comprises several cylinder spaces arranged axially in pairs and concentrically arranged inside the envelope surface thereof. In the cylinder spaces, which are arranged axially in pairs and are separated by a partition, there are arranged a drive piston and a pump piston interconnected by a piston rod passing in a sealed manner through the partition.

Abstract: A control rod for a nuclear reactor comprises a number of elongated absorber plates (13-16) which are each provided with a plurality of channels (18b), said channels extending substantially perpendicularly to the longitudinal direction of the absorber plate, containing powdered boron carbide or other powdered absorber material which gives off gas and swells upon irradiation, and being hermetically separated from the surroundings of the control rod by an edge portion (30), which is arranged at an edge (31) running in the longitudinal direction of the absorber plate and comprises a gas-tight edge (31) and a longitudinal space (32) arranged inside said edge and being in open communication with and permitting a gas flow between the different channels in the absorber plate.

Abstract: A separation means for a liquid medium containing undissolved constituents comprises a chamber (10) with dynamic membrane (11, 12) arranged therein, said membrane consisting of a porous support matrix (11a, 12a) or other support matrix with through holes, and a layer (11b, 12b) of a small-sized particle material generated thereon in the chamber. In such a separation means the flow of the liquid medium is split into two streams, one constituting the permeate stream which penetrates through the membrane and the other constituting the reject stream which flows past the membrane.

Abstract: A fuel assembly for a boiling water reactor has a fuel channel of generally square cross-section and provided with four walls, which fuel channel surrounds a plurality of fuel rods. Adjacent to its upper edge, the fuel channel is provided with a spacer having a corner portion and two arms extending from the corner portion and making an angle of 90.degree. with each other. The corner portion of the spacer engages a first corner of the fuel channel, and the two arms each make contact with the outer sides of the two fuel channel walls that meet at the first corner. Each arm is provided, at its outermost part, with a diagonally directed, horizontal projection which is inserted into a corresponding aperture in the adjacent fuel channel wall, the two projections thereby bridging across a respective one of the two corners of the fuel channel which are closest to the said first corner.

Abstract: A sealing member in the form of a plate (15) for a connection piece or a similar connection part for a conduit for liquid or gas on a container comprises a portion with a number of sheet elements (15b-15f) having a shape resembling a U-beam and comprising a web part (15'b-15'f) and flange parts (15"b-15"f). The web part of such a sheet element is arranged to constitute part of the flat sides (18, 19) of the plate, and each flange part of such a sheet element is arranged close to a flange part of an adjoining such sheet element or close to a flange part (15"a-15"g) of another sheet element (15a, 15g) located outside said portion and otherwise comprising a part (15'a, 15'g) arranged to constitute a part of the flat sides of the plate. Flange parts arranged adjacent to each other are connected by a hinge (21) at those edges of the flange parts which are facing away from the flat sides of the plate, the plate thus being foldable.

Abstract: A fuel assembly for a boiling water reactor has a bundle of fuel rods consisting of a top tie plate and a bottom part which, together with a plurality of fuel rods, constitutes a rigid unit. The fuel rod bundle is surrounded by a fuel channel (1), to which there is attached a fixing member (2) cast in stainless steel. The fixing member (2) is attached to a vertical projection (3), extending from the top tie plate, by means of a bolt (4) which is loaded with a tensile force and a sleeve (10) which is loaded with a compressive force and which surrounds the bolt and is arranged in the fixing member, the coefficients of thermal expansion of the bolt and the sleeve being less than that of the fixing member.

Abstract: A heat-generating member (4) is arranged in a water-filled pressure vessel (1) which is provided with a pressure relief valve or the like. The water of the pressure vessel can be partly evaporated, thereby acting as a heat sink for the generated heat. The walls of an outer vessel (6) surround at least a lower part of the pressure vessel (1) in such a way that a closed, relatively small auxiliary space (7) is formed between the two vessels. The auxiliary space (7) communicates via at least one tube (8) with an open evaporation pool (9), which is arranged above the cover (2) of the pressure vessel (1). A tube coil (10), disposed in an upper part of the pressure vessel, is connected by both ends to the evaporation pool (9).

Abstract: During local cleaning of metallic surfaces (15, 24) on parts included in the primary circuit of a nuclear reactor, which surfaces are coated with corrosion products, in connection with inspection of the surfaces, the coated surface, while being located below the surface of the reactor water (13) in the reactor vessel (10) or reactor pool (12) of the nuclear reactor, is arranged in contact with an electrolytically permeable spacer (16) of an electrically insulating material which, at a distance from the coated surface, is arranged in contact with a body (170 of electrically conductive material. An electrolyte (21) is supplied to the spacer and an electrical potential difference is maintained between the coated metallic surface and the body of conductive material by connecting the surface to the positive pole (18) and the body to the negative pole (19) of a voltage source (20).

Abstract: The water flowing in a nuclear reactor is analyzed, while the reactor is in operation, by conducting water from the reactor vessel substantially without reduction in pressure or temperature past test surfaces (e.g. tubes) with different electrochemical potentials relative to the reactor water. Deposits formed on the test surfaces, which are substantially caused by colloidal particles in the water, are examined, preferably with regard to radioactive content.