Abstract: Spacers (10) with a cell-formed lattice-work for retaining parallel elongated elements such as fuel rods (5) into a bundle in a nuclear reactor fuel assembly are arranged in a suitable spaced relationship to each other along the bundle, and the cells are formed from tubular sleeves (1). Each one of these sleeves (1) offers a passage for one of the elements in order to fix the elements in relation to each other. Substantially half the number of sleeves (1) in a spacer (10), distributed evenly over the cross section of the bundle, are located in a first plane across the bundle and are joined to each other inside a first frame (11) surrounding the bundle, thereby forming a lattice of sleeves (1) and gaps (13). The remaining sleeves (1) of the spacer (10) are joined together inside a second frame (12) surrounding the bundle and are located in a second plane, separate from the first plane, across the bundle.

Abstract: A spacer for retaining parallel, elongated fuel rods includes a plurality of cells which are formed from tubular sleeves internally provided with fixed supports and at least one spring arranged opposite to the fixed supports. The spring is intended to make contact with a fuel rod inserted into the sleeve and is formed as a leaf spring which is cut out of the wall of the sleeve and which, when the sleeve is empty, is bent into the sleeve. The leaf spring is adapted, in tensioned position when the fuel rod is inserted into the sleeve, to be returned to a position substantially coinciding with the wall of the sleeve.

Abstract: A fuel assembly for a nuclear reactor with a number of parallel fuel rods which are retained by means of spacer lattices and guide tubes (3), which guide tubes (3) are also fixed to the spacer lattices, a top tie plate (4) and a bottom tie plate between which the guide tubes (3) with associated fuel rods are fixed. The top tie plate (4) has been provided with through-holes (10) for connection to a top sleeve (7) joined to the upper end surface of the respective guide tube (3). According to the invention, there is arranged inside the top sleeve (7) a first locking element (9) for cooperation with a second locking element (13). This is arranged on a guide sleeve (11) which is insertable through a hole (10) in the top tie plate (4), which hole corresponds to the respective top sleeve (7).

Abstract: A fuel assembly in the form of an elongated channel having several corners is connected to a coolant intended to flow through the channel. A bundle of similarly elongated fuel rods, retained by a plurality of spacers, is arranged in the channel, and arranged in the upper part of the fuel assembly, at least between a pair of spacers, is a sleeve formed of a sheet around the bundle. The sleeve has an external shape which conforms closely to the walls of the fuel assembly and is perforated by a large number of openings, the total surface of which is at least as large as the sheet surface remaining on one side of the sleeve.

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 nuclear reactor assembly including a substantially cylindrically-shaped and vertically extending pressure vessel. A uniquely constructed bracket assembly is arranged for mounting a water distributor against an inner wall of the cylindrically-shaped pressure vessel, with the bracket assembly including a spring assembly capable of biasing an inlet conduit of the water distributor into abutting contact with an inlet nozzle extending through a wall of the pressure vessel.

Abstract: In a water moderated reactor, which has a plurality of vertically arranged fuel assemblies enclosed in a moderator tank provided with a cover and positioned by an upper core grid, a sprinkling device is arranged above the core grid and below the cover. The sprinkling device is composed of a plurality of substantially horizontal main sprinkling tubes each provided with a plurality of nozzles. A common distributing pipe supplies sprinkling water to the main sprinkling tubes. There are a auxiliary tubes above the main sprinkling tubes and connected to them hydraulically and mechanically by a plurality of transverse metal tubes. The cover has a detachable lower part in the form of a ring to which the sprinkling device is connected.