Abstract: Waste from a nuclear power plant, containing organic ion-exchange resin containing radioactive metals, is decomposed to form volatile substances by means of oxidation in an acid, aqueous liquid (8). Radioactive metal ions thus dissolved in the liquid, which are precipitable with hydroxide, are then caused to precipitate by the addition of a hydroxide (10) at a pH value of at least 9, and the metal compounds thus precipitated are separated from at least most of the liquid. Radioactive caesium and strontium ions in this liquid are removed therefrom. The liquid (24) separated from precipitated metal compounds and freed from caesium and strontium ions is released to a recipient, with the remaining substances still dissolved in it, and the precipitated metal compounds (11k, 11s) are solidified in a deposition container (22). The ion-exchange resin preferably consists at least partially of sulphonated ion-exchange resin and the hydroxide preferably of sodium hydroxide or some other alkali metal hydroxide.

Abstract: A nuclear fuel assembly containing a plurality of vertical fuel rods and possibly occasional vertical water-filled rods, which are surrounded by a fuel channel of substantially square cross-section and which are divided, by means of a vertical channel for water of substantially cruciform cross-section, into four sub-bundles. Each fuel rod contains a stack of circular-cylindrical pellets of a nuclear fuel arranged in a cladding tube. Each sub-bundle consists of, in all, twenty-five rods arranged in a lattice containing 5.times.5 rods. The cladding tube of each fuel rod has a wall thickness in the range 0.50 to 0.70 mm and an external diameter in the range 8.5 to 10.3 mm.

Abstract: Sintered nuclear fuel bodies are manufactured by pressing a powder of UO.sub.2 containing 1-20 percent by weight Gd.sub.2 O.sub.3 and up to 20 percent by weight U.sub.3 O.sub.8 into a pressed body and sintering the pressed body, the Gd.sub.2 O.sub.3 at least partly consisting of monoclinic Gd.sub.2 O.sub.3. The monoclinic Gd.sub.2 O.sub.3 used can be manufactured by heat treatment of cubic Gd.sub.2 O.sub.3 at a temperature of at least 1250.degree. C. By employing monoclinic Gd.sub.2 O.sub.3 a considerably increased homogeneity with respect to solid solution of gadolinium in the UO.sub.2 structure is obtained. Particularly favorable results are obtained if the sintering is carried out in a sintering atmosphere which, at 1750.degree. C., has an oxygen partial pressure which is higher than 10.sup.-7 atm.

Abstract: The invention relates to a spacer arranged to retain and fix elongated fuel rods into bundles insertable into a nuclear reactor fuel assembly, said spacer being of a zirconium alloy having a low neutron absorption. To counteract play and hence wear in case of increasing burnup when the springs relax and the rod diameter is reduced by shrinkage, the spacer is made with different textures in the springs (2, 3) and the surrounding structure (1, 6). The difference in texture gives the springs a great axial irradiation growth and the surrounding structure a small axial irradiation growth, which contributes to a remaining deflection tendency of the springs in relation to the surrounding structure during the life of the fuel assembly.

Abstract: Nuclear fuel assembly having four bundles of fuel rods, at least one fuel bundle being made with twenty symmetrically arranged fuel rod positions, the number of fuel rod positions in each of the remaining fuel rod bundles being at least sixteen and at most twenty-five.

Abstract: A method for simultaneously testing a plurality of fuel rod assemblies for leakage of radioactive gas, comprising the steps of removing the cover from a nuclear vessel containing the fuel rods, positioning a fixture over the fuel rods, reducing the hydrostatic pressure surrounding the fuel rods allowing gas to leak into the surrounding water, collecting water from about each fuel rod assembly in a separate chamber, separating gas from the water and testing the gas for the presence of radioactivity.

Abstract: Boiling reactor comprising a reactor vessel and a moderator tank arranged therein which surrounds a reactor core with a plurality of vertically arranged fuel boxes. A moderator tank space located below the reactor core is provided with inlet openings for cooling water streaming through the reactor core and is in direct hydraulic connection with the lower ends of the fuel boxes. The wall of the rector vessel is provided with an opening for the supply of a first feed water flow to the cooling water flowing into the lower end of the reactor core, with the upper ends of the fuel boxes being arranged in hydraulic connection with a plurality of riser tubes by the aid of which a steam and water mixture flowing out from the fuel boxes is conducted to a plurality of water separators.

Abstract: A spacer assembly for vertically supporting a bundle of fuel rods, wherein the spacer assembly comprises a plurality of separate cells each surrounding a separate fuel rod. Each cell includes a pair of polygonally shaped members interconnected by at least one spring assembly, wherein the spring assembly provides a horizontal component of motion to cooling water circulating vertically through the bundle of fuel rods.

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.

Abstract: A fuel assembly includes a bundle of vertical fuel rods. Some of the rods are tying rods provided with extended upper end plugs, and the rest of the rods are spring-furnished ones, the spring forces balancing the tying forces exerted by the tying rods between a top plate and a bottom plate. The top plate is grid-like and provided with attachment holes for the upper end plugs. The lower end plugs of the tying rods are screwed in threaded holes in the bottom plate. Each of the upper end plugs of the tying rods has a portion located above the top plate and provided with a nut. Rotation of the nut is limited by at least one downwardly directed projection on the nut, the end surface of which lies below the upper edge of the top plate. The maximally allowable length of this projection is less than the maximum shortening of the springs that can be carried out by exerting a downwardly directed force on the top plate.

Abstract: A device for transporting nuclear fuel rod cladding tubes transversely along a production line has a travel surface for the tubes and a transport chain running in the direction of transport parallel to the travel surface. The chain has a plurality of two-armed levers pivotally mounted thereon and springs pulling these levers in the direction of the travel of the chain. The levers have rollers at their ends which can engage between tubes on the travel surface. The springs are of such strength that the resistance to movement of a predetermined number of tubes prevents them from rising up, so that the rollers roll underneath the tubes, but permits them to rise up when a small number of tubes is in front of them to engage the tubes and pull them along the track. This provides in effect a storage if too many tubes are found on the track at any one time.