Abstract: A protection flap provided on mixing vanes of structural or mid-span mixer grids in order to eliminate or substantially reduce fretting of fuel rods retained by such grids. The flap is an extension or addition of vane material bent upwardly so as to be substantially parallel to the longitudinal axis of the fuel rod being retained. The flap provides a smooth, vertical surface against which the fuel rod contacts in case of vibration, bowing or shifting.

Abstract: An eddy-current probe (10) is moved in the axial direction of the clad of the rod (1), a first position of the probe (10) is determined in the axial direction, for which a signal from the probe is representative of the presence of the internal surface of the bottom end plug of the rod (1) and at least one second position for which the signal from the probe is representative of the presence of the end part of the spring of the fuel rod (1) or of the internal surface of the top end plug of the fuel rod (1). The total length and/or the length of the fissile stack are calculated from the first position and from the second position of the probe (10). The measurements may be performed inside the spent fuel storage pond of a reactor.

Abstract: A spacer grid spring (6) consists of a single metal leaf including two end parts (6a, 6b) substantially in the same plane and a central part (6c) out of the plane of the end parts (6a, 6b). At least one of the end parts (6a, 6b) is laterally provided with two flanges (6d, 6e) folded out of the plane of the end part (6a, 6b), in the opposite direction from the central part (6c) of the spring (6). The call wall (5) intended to receive the spring (6) includes, in an arrangement adjacent to each of two dimples (7a, 7b) placed at the ends of the wall (5), a part (8a,8b) for holding an end (6a, 6b) of the spring, and an opening (10a, 10b) passing through the wall (5) adjacent to the holding part (8a, 8b).

Abstract: The present invention is directed to a rod connector assembly for removably securing a control rod to a spider structure. The rod connector assembly includes a tubular boss fixedly secured to the spider structure and a mounting assembly which includes a receiving structure and a biasing structure. The assembly also includes a cap having a cavity formed therein, the biasing structure including a driver and disposed in the cavity such that the driver extends outwardly from the cavity and into the boss, and wherein the cap is secured to the boss. When the control rod is in a prescribed position with respect to the boss, the mounting assembly is operative to resist rotation of the control rod upon application to the control rod of an amount of torque less than a predetermined amount of torque.

Abstract: A rod connector assembly for removably securing a control rod to a spider structure and adapted for use in conjunction with a crimping tool. The rod connector assembly includes a tubular boss fixedly secured to the spider structure, the boss including at least one access hole and interior threads formed on an interior surface of the boss. A securement structure includes a coupling adapted to be fixedly secured to the control rod. The coupling includes a shaft having external threads, an upper end, and a lower end, the lower end of the shaft adapted to be fixedly secured to the control rod; a deformable collar projecting upwardly from the upper end of the shaft; and a cap adapted to be fixedly secured to an upper end of the boss and including at least one groove corresponding to the access hole(s).

Abstract: A process for treating an aqueous solution mainly containing nitric acid and hydrofluoric acid. The process involves distilling to provide an aqueous solution concentrated in nitric acid and hydrofluoric acid for the separation thereof, then separating by distillation.

Abstract: The lower part (31) of the pole (10) carries an expansible bush (40) engaged and fixed on the outer surface of the part (31) by one of the ends (41) of the bush and comprising longitudinally extending slots defining resiliently bendable strips. A group of balls (39) mounted to be radially movable in openings (38) in the lower part (31) of the pole (10) and bearing against the bendable strips of the expansion bush are movable between a retracted position and a position for expanding the bush (40), by a cylindrical cam (36) connected to an actuating rod (20). The device permits inserting the locking sleeve (8) in the guide tube (13) without risk of deformation of the end strips of the guide tube (13).

Abstract: The invention relates to the dissolving of plutonium and/or other radioactive elements in an aqueous solution by microwave heating.According to the invention, solid or liquid products containing plutonium and/or other radioactive elements are introduced into a container (7) containing an acid solution, comprising hydrofluoric acid and nitric solution, followed by the microwave heating of the solution containing these products using a chamber or tank (5) placed in a tight enclosure (1), which is supplied with microwaves by means of a coaxial cable or a waveguide (11) connected to the generator (9) located outside the enclosure.The solid products can be plutonium dioxide PuO.sub.2 or organic or mineral radioactive waste materials such as gloves, cellulose products, ion exchange resins, etc. The liquid products can be contaminated organic solvents such as tributyl phosphate in dodecane.

Abstract: A method of excavating an underground area liable to flooding or collapsing during excavation, wherein the area is susceptible to disaggregation by high pressure water jet and is located above rock of strength suitable for drifting a gallery comprises drifting a gallery in the rock beneath the area, freezing at least a perimeter of the area to form a frozen perimeter, and excavating material from within the frozen perimeter using a high pressure water jet and one or more boreholes between the gallery and the area. Preferably the whole area is frozen for excavation.

Abstract: The device comprises a platform (13) fixed in a horizontal position on a support structure (3) for the fuel assembly (4) placed under water in a pool (1). The platform (13) includes a table (14) for shifting a carriage (35) in two crossed directions in a horizontal plane and an arrangement (27) for clamping the fuel assembly so as to immobilize it in the machining position. The fuel assembly (4) is placed in the machining position by a hoisting device (6). A table (15) mounted on the table (14) for movement in one of said crossed directions in the horizontal plane is returned elastically (40) in the direction toward the assembly (4). A frame (16) is fixed on the table (15) and permits shifting a tool-carrying carriage (49) in a direction defined by the frame (16). A motorized grinding unit (17) is fixed on the tool-carrying carriage. The device may be used in particular for cutting or levelling the surface of a spacer-grid (8) of a used fuel assembly (4).

Abstract: The invention concerns the recovery of Pu (IV) by using crown compounds.According to the invention, the aqueous solution containing the plutonium (IV) is placed in contact with at least one crown compound, for example DCH 18C6, dissolved in an organic diluting agent, such as benzonitrile. In the case where the solution only contains traces of Pu, it is possible to use a crown compound secured to a solid phase, such as silica.The aqueous solution is a concentrated solution of fission products, an effluent originating from an irradiated nuclear fuel reprocessing installation or a concentrated solution of plutonium with americium.

Abstract: Process for carrying out an inspection or monitoring round of a nuclear site (5) consisting of recording in a central computer (22) connected to a radiofrequency transmitter/receiver or transceiver (24) a combination or sequence of different collection or reading points (12) grouping sensors (10) constituting the round to be performed. This sequence is copied again into a memory of a portable microcomputer (26) carried by the watchman during the round and connected to a radiofrequency transceiver (28). Each connection point (12) is validated and this validation is transmitted to the central computer (22). The sensors are checked and any abnormal condition is indicated to the central computer (22). All the checks carried out are recorded in the portable microcomputer (26) and copied again at the end of the round into a central computer (22) in such a way that they can be processed.

Abstract: The duplex tube (1) comprises a tubular core (2) and a cladding or covering layer (3) made from an alloy, the base metal of which is identical to the base metal of the alloy constituting the tubular core (2).

Abstract: Oxidation treatments by ionic bombardment or post-discharge result in the formation on the surface of passivatable metals and alloys of a layer of oxide having a thickness of a few micrometers which protects the substrates from subsequent corrosion. The gas activated by the electric discharge is put in contact with the surface of the part (2) to be oxidized, which is brought to a temperature of 350.degree. to 650.degree. C. The treatment may be employed in particular for forming a protective covering on an element or a complete framework composed of a zirconium alloy of a fuel assembly of a water-cooled nuclear reactor.

Abstract: The disclosure describes an apparatus for performing at least two successive chemical reactions in the same container. In order to successively carry out several chemical reactions in the same container (10), e.g. dosing uranium in the presence of plutonium and fission products, the container is placed in a working station above which issue tubes (16, 20) for supplying the products necessary for the reactions. When a product has to be introduced, a computer controls the descent of the corresponding tube. When the product may react inopportunely if it drops into the container (10) outside the time intended for this purpose, the lower end of the product supply tube (16) is automatically laterally displaced with respect to the container, when the tube is in the top position, e.g. by the cooperation of a pawl (102) with a slot (100) forming a cam.

Abstract: For taking liquid samples, such as active solutions in an irradiated nuclear fuel processing plant within a confined area (10) located below a protective slab (12), use is made of vacuum pots (44), which are pneumatically transferred into a vessel (14) located beneath the slab and which are engaged on needles (40) supplied with fluid to be sampled and projecting into the bottom of the vessel. A pot (44) is moved pneumatically into a nacelle, pod or basket (76) of a rotary drum (72) by means of a transfer duct (60), which passes through a slab element (62) installed in a rotary plug (20). The positioning of the pot vertically with respect to a needle (40) is ensured by the combined rotations of the drum (72) and the plug (20). A vertical displacement of the slab element (62) ensures the sampling before the filled pot is pneumatically evacuated by the reverse path.

Abstract: A head for taking liquid samples and intended to be used in a sampling system associated with a nuclear fuel processing installation, includes a sampling tank (10) in which is removably received a needle body (16), which supports a sampling needle, to which can be fixed a vacuum sampling container (46). The needle body (16) has an extension (34) provided with holes, which surrounds the lower part of the needle (18) immersed in a cavity (26) of the sampling tank (10). The lower end (36) of said extension (34) seals a draining passage (32), which opens into the bottom of the cavity (26). This makes it possible to ensure a larger liquid quantity.

Abstract: The invention relates to a glove holder unit for a confinement enclosure.The aim of the invention is to produce a unit making it possible to easily change a protective glove for the hand.This aim is achieved with the aid of a glove holder unit having a sleeve (11), for protecting the arm and the forearm, assembled to a working glove (15), protecting the hand, and placed in an enclosure. The glove holder unit comprises means (49) for locking an assembly means (17) of the glove (15) and the protective sleeve (11). The locking means (49) being mobile between a locked position, in which they maintain the assembly means (17) and the glove (15) outside the enclosure (1) and an unlocked position in which they allow the passage of the glove (15) and its assembly means (17) between the interior and the exterior of the enclosure.

Abstract: The adaptor plate (11) comprises ribs (12) which are substantially perpendicular to its faces, projecting from its lower face, delimiting between them cells and zones (15) into each of which emerges a plurality of through-openings (16) of substantially square cross-section which are arranged in a predetermined pattern.

Abstract: A process and apparatus for the transfer out of a tight enclosure of a fluid solution contained in a polluted container (R1). The transfer is accomplished without removing the polluted container from the enclosure and without breaking the seal of the polluted container. After a clean container (R2) is placed in a receptacle (30) normally isolated from the remainder of the enclosure, the solution is transferred into the clean container (R2) vacuum by a needle. Transfer of the clean container out of the enclosure takes place pneumatically following rotation of a casing containing the receptacle.