Abstract: A device for determining, by detection and calculation, nuclide contents of radioactive inert gases. The device includes a measuring chamber (1) which contains the inert gases, a detector (3) which detects gamma radiation emitted from the radioactive inert gases, calculating members (5) which, based on the detected gamma radiation, calculate the content of the different nuclides.

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: The present invention relates to a fuel assembly (1) and a method therefor. The fuel assembly is intended for a light-water cooled nuclear reactor and comprises a first and a second locking member (9a, 9b, 10), a plurality of elongated elements (3, 3a) wherein each of the lower ends of the elongated elements is provided with an end plug (3b). The end plug (3b) is arranged guided or locked in an end plate (6) which comprises at least two adjacently disposed plug holes (6b) for receiving one end plug (3b) each. The first locking member (9a, 9b) is made in an end plug (3b) and has a concave shape and the second locking member (10) is arranged slidable in a locking hole (6c) which is adapted to extend between the two adjacently disposed plug holes (6b) and opening out into these. The second locking member (10) is made with a length exceeding the length of the locking hole (6c) and has end surfaces with shapes intended for cooperation with the concave surface of the first locking member (9a, 9b).

Abstract: A nuclear reactor plant with a light water reactor comprises a containment (1) having an upper space (2) and a lower space (3). The lower space is separated from the upper space by a separating member (4) and arranged to house a cooling medium (16). Furthermore, the plant comprises a reactor vessel (9) housing a reactor core (10) and provided in the upper space (2). The separating member (4) comprises a portion (7) which is arranged to be located at such a position that the surface portion (7) facing the lower space (3) is in contact with the cooling medium (16). The reactor vessel is provided above the portion (7).

Abstract: The present invention relates to a fuel assembly with a substantially square cross section for a light-water reactor. The light-water reactor comprises a plurality of fuel rods (4) extending between a top tie plate (5) and a bottom tie plate (6). A fuel rod (4) comprises a cladding tube (7a) with a first and a second end which surround a column with fissionable material (7b). According to one aspect of the invention, at least one fuel rod (4) is provided with an axial gap (19) in the fissionable material (7b), such that fissionable material (7b) is arranged on both sides of the axial gap (19) in the fuel rod (4).

Abstract: A fuel assembly for a boiling water reactor comprising at least one rotary cell (13a-13d) which has fuel rods (4) arranged in a number of concentric rings with a substantially circular shape, and a steam conducting channel (17a-17d) arranged in the centre of the concentric rings through which steam flows upwards through the fuel assembly. At least certain of the fuel rods in the rings are arranged such that their upper ends are displaced in relation to their lower ends in the tangential direction such that water and steam are brought to rotate around the steam conducting channel.

Abstract: The present invention relates to a fuel assembly for a light-water nuclear reactor with a substantially square cross section which comprises fuel rods (4) extending between a bottom tie plate (16) and a top tie plate (17). A coolant is adapted, during operation, to flow upwards through the fuel assembly. According to one aspect of the invention, the fuel assembly comprises a plurality of fuel units (3) stacked on top of each other, wherein each fuel unit (3) comprises a plurality of fuel rods (4) extending between a top tie plate (17) and a bottom tie plate (16). The fuel units are arranged attached to a support structure (4a, 14, 14a, 14b) extending through the whole fuel assembly such that axial gaps are formed between the fuel units (3). One of the tie plates is freely movable relative to the support structure.

Abstract: A fuel assembly (1) comprising a plurality of elongated elements (3) filled with nuclear fuel and at least one component (5, 6, 7) for retaining the elongated elements (3), wherein the retaining component (5, 6, 7) is completely or partly made of a ceramic material.

Abstract: A fuel assembly (1) for a boiling water nuclear reactor comprising a plurality of vertical fuel rods (3) which are arranged in spaced relationship between a bottom tie plate (6) and a top tie plate (5). The bottom tie plate (6) is provided with through-holes (6a) for the passage of a coolant (F). Further, the fuel assembly (1) comprises a bottom support (10) which is formed substantially from a downstream and an upstream flat surface (12, 13) and four side surfaces (14). The flat surfaces (12, 13) and the side surfaces (14) form a parallelepiped which surrounds a cavity. A filtering member is arranged in the upstream flat surface (13) and comprises a plurality of through-holes (11).

Abstract: A fuel box for a nuclear fuel bundle for a boiling water reactor is manufactured by zirconium alloy plates. The plates have a composition such that the material after beta quenching and heat treatment will have a ductile, so called basketweave structure.

Abstract: A reactor core for a boiling water nuclear reactor includes a plurality of fuel assemblies (40) with a plurality of vertical fuel rods (10) and possibly occasional vertical water-filled rods or channels (32, 48, 49, 50, 51) which are surrounded by a fuel channel (1). Between the fuel assemblies (40) there are arranged water gaps (37a, 37b). At least one fuel assembly (40) has at least one outer, reduced corner portion (41) facing a gap (37a, 37bb), and the number of fuel rods (10) in each such fuel assembly (40) is reduced by a number corresponding to the number of reduced corner portions (41) therein.

Abstract: The present invention provides a method and apparatus for fuel handling in a nuclear reactor. The nuclear reactor has a reactor vessel comprising a reactor core with a plurality of fuel assemblies and control rods. A fuel pool is arranged adjacent to the reactor vessel. A group comprising at least a plurality of fuel assemblies is simultaneously lifted out of or into the reactor vessel with a single gripper, the gripper having a plurality of gripping devices. The group is transported between the reactor vessel and the fuel pool by means of the gripper.

Abstract: The invention relates to a nuclear fuel element for pressurized-water reactors comprising a fuel cladding of a zirconium alloy composed of two parts. The inner part constitutes a supporting part of a conventional zirconium and the outer part a corrosion-resistant layer of zirconium with 0.65-0.95% Sn and 0.4-0.5% Fe. The difference in Sn content between the inner and outer parts must not exceed 0.7%. The cladding is finally heat-treated within the range 450 to 510.degree. C.

Abstract: The present invention relates to a method and a device for correction of the movements of a suspension device and positioning thereof in a fluid. The suspension device is provided with a first and a second end, and the first end is suspended from a point (S). A correction device is arranged at the second end of the suspension device and adapted to generate a force which provides an acceleration in the fluid so that the position of the second end of the suspension device is corrected.

Abstract: Metal ions are added to a circuit (20, 30) for the reactor water or feed water of a nuclear plant. This is accomplished by dissolving a soluble metal compound the counter-ion of which is possible to decompose to gaseous products and water in water in a reaction vessel (41) in an equipment arrangement (40). The solution is subsequently conducted to a series of vessels (42) for the decomposition of the counter-ion. The solution is then possibly transformed to a mixture or a slurry which is conducted to a vessel (43) for degassing the gaseous products before the addition to the circuit (20, 30) for the reactor water or feed water.

Abstract: The present invention is used in fuel handling for lifting of fuel assemblies and/or control rods out of/into a reactor vessel in a nuclear reactor. The reactor vessel comprises a reactor core with a plurality of fuel assemblies and control rods. A fuel pool is arranged adjacent the reactor vessel. A cassette comprising a plurality of storage positions for fuel assemblies and/or control rods is arranged near the reactor core, whereupon fuel assemblies and/or control rods are lifted out of the reactor core and arranged in the cassette. The cassette is then transported to the fuel pool for temporary storage.

Abstract: The present invention relates to a fuel assembly in or for a boiling water reactor, comprising a plurality of vertical fuel rods extending between a top and a bottom tie plate and surrounded by a sleeve-formed casing where the fuel rods are positioned with the aid of a plurality of axially separated spacers. The invention is characterized in that only one fuel rod is detachably arranged in the top tie plate and in the bottom tie plate and in that at least one of the other fuel rods is fixed to the bottom tie plate and adapted to extend above the top tie plate to obtain a tensile-force-transmitting connection with the bottom tie plate.

Abstract: A fuel assembly for a boiling water reactor comprises a plurality of first full-length fuel rods arranged in an orthogonal lattice, wherein each fuel rod is included in two rows of fuel rods perpendicular to each other, and a number of second fuel rods arranged in parallel with the first fuel rods and having the length considerably smaller than the length of the first fuel rods. The second fuel rods are arranged in the lower part of the fuel assembly in the space which is formed between a number of first fuel rods located adjacent to each other, that is, in a position which does not belong to the orthogonal lattice.

Abstract: A spacer for retaining and positioning elongated elements at one or a plurality of levels in a nuclear reactor fuel assembly comprises a grid structure of joined-together sleeve cells. A coolant is adapted to flow upwards through the fuel assembly. The majority of the sleeve cells are provided with an upstream edge with a waveform. The edge is waveformed in such a way that the upwardly flowing coolant first encounters a peak of the wave which is disposed between the joints of the sleeves and thereafter a valley of the wave which is disposed at the joints of the sleeves. The peaks are arranged closer to a center of the sleeve cell than the valleys. Between the peaks and valleys, oblique edges are formed.

Abstract: A spacer including a plurality of cells to retain and mutually fix parallel, elongated elements, extending through the cells, in a bundle in a fuel assembly for a nuclear reactor where a coolant is adapted to flow from below and upwards. Between the cells, secondary channels are formed. At least one of the spacers includes at least two deflection members being substantially arranged so as to be surrounded by the cells. The deflection members are axially spaced-apart in the direction of flow of the coolant and relative to each other at a pitch angle for stepwise axial and radial deflection and guiding of at least part of the coolant flow towards fuel rods included in the bundle. The fuel rods are arranged close to the secondary channels.