Abstract: A fuel rod alignment template and method for loading fuel rods in a nuclear fuel assembly. Front and rear guide plates are provided with a plurality of holes corresponding to cells in the fuel assembly to be loaded. The guide plates are rigidly connected together by connecting rods that extend beyond the front guide plate and are sized to be received in the guide tubes of the fuel assembly. When attached to the fuel assembly with the front guide plate abutting the guide tubes the holes in the guide plates and cells in the grid assemblies of the fuel assembly are in coaxial alignment. This provides positive guidance to the fuel rods as they are inserted into the fuel assembly to prevent mis-tracking and damage to the fuel assembly.

Abstract: The filtration plate (10), arranged in the lower part of the fuel assembly and ensuring the retention of particles contained in the cooling fluid of the reactor, has at least one active zone where it is pierced with holes (12) of a size determined according to the size of the particles to be retained. The active zones of the filtration plate come into alignment with a water-passage hole through the lower core plate of the reactor when the assembly is in operation. The water-passage orifices of the filtration plate (10) can consist of cutouts of square or triangular form or of stamped parts of the plate or be delimited by parallel lamellae constituting a grating.

Abstract: A method for lowering the corrosion potential on components formed from carbon steel, alloy steel, stainless steel, nickel based alloys, or cobalt based alloys, and exposed to high-temperature water comprised of oxidizing species, comprising: providing a reducing species in the high temperature water that can combine with the oxidizing species, and forming the component to have a catalytic layer of a platinum group metal.

Abstract: A high energy, charged particle accelerator, and radiation sources utilizing such accelerator are provided. More particularly, a high yield neutron generator and apparatus for the use of such generator are provided. The generator utilizes an ion source, a target adapted to generate neutrons when bombarded by high energy ions and an accelerator tube between the source and target. A multistage cascade rectifier is paraxial with the accelerator tube and has a voltage gradient which substantially matches that of the accelerator tube. The cascade rectifier preferably surrounds the accelerator tube and has equipotential metal plates on each side of each stage, the potential gradients between each pair of plates being substantially uniform and being substantially equal to the voltage gradient in the adjacent section of the accelerator tube. Generator elements may be enclosed in a pressure vessel and a moderator may be provided in the vessel, near the target to thermalize neutrons emitted from the target.

Abstract: A process for dissolving plutonium, and in particular, delta-phase plutonium. The process includes heating a mixture of nitric acid, hydroxylammonium nitrate (HAN) and potassium fluoride to a temperature between 40.degree. and 70.degree. C., then immersing the metal in the mixture. Preferably, the nitric acid has a concentration of not more than 2M, the HAN approximately 0.66M, and the potassium fluoride 0.1M. Additionally, a small amount of sulfamic acid, such as 0.1M can be added to assure stability of the HAN in the presence of nitric acid. The oxide layer that forms on plutonium metal may be removed with a non-oxidizing acid as a pre-treatment step.

Abstract: A BWR coolant recirculation system includes a pump deck disposed in a downcomer and fixedly joined to a reactor pressure vessel and reactor core shroud. A plurality of circumferentially spaced reactor internal pumps (RIPs) are joined to the deck and operable in a pumping mode for pumping downwardly a reactor coolant from the downcomer and into a core inlet. In a pump inoperable mode, a portion of the coolant bypasses the RIPs for allowing increased natural recirculation of the coolant from the downcomer and into the core inlet.

Abstract: The invention makes it possible to measure the degree of radioactive radiation emitted by large pieces. It includes two large gamma ray detectors (12A, 12B) placed opposite each other and whose spacing is adjustable. They are completed by a photoelectron multiplier (14A, 14B). The piece (2) to be measured is suspended so as to be brought between the two detectors (12A, 12B). The positioning of these detectors is obtained with the aid of a computer and a system (22) for recognizing the shape of the piece (2) functioning with the aid of optical clip-on lenses. The fact that the two detectors are position-adjustable makes it possible to take account of the shape of the piece to be measured. An application is the recovery of materials originating from nuclear installations with the view to re-using the materials.

Abstract: A plug and method for plugging a penetration in a pressure vessel wall having a sleeve protruding through the penetration. The sleeve is cut at a point between the interior and exterior surfaces of the pressure vessel wall. The cut portion of the sleeve extending beyond the exterior surface of the pressure vessel wall is removed. A plug sized to fit within the penetration is inserted into the penetration so that one end of the plug is flush with the exterior surface of the pressure vessel wall. A weld pad is deposited on the end of the plug and the exterior surface of the pressure vessel wall.

Abstract: There is disclosed a grid in a nuclear fuel assembly for supporting fuel rods and thimbles, which includes a plurality of elongated straps intersecting perpendicularly with each other to define a plurality of grid cells. A plurality of engaging units are provided on the grid cells for supporting thimbles, respectively. Each engaging unit includes at least one engaging member provided on at least one of the opposite ends of the straps of the grid cell and defining an engaging portion. A plurality of cylindrical sleeves are arranged in the grid cells for supporting thimbles, respectively. Each sleeve has at least one engaging projection associated with the engaging portion of the engaging member. The engaging projection of the sleeve and the engaging portion of the engaging member are formed such that when the sleeve is turned circumferentially, the engaging projection is held in engagement with the engaging portion.

Abstract: There is disclosed a process and a plant for bleaching cellulosic materials by aid of ozone. A concentrated solution of ozone in an aqueous medium (strong water) is supplied under pressure to the materials suspended in an aqueous medium and is mixed therewith in a mixing device. The mixture is conducted through a reaction vessel, the bleached material is separated from the bleaching liquor, and possibly present residual ozone is destroyed. The plant includes an arrangement for preparing a pulp suspension, at least one bleaching tower to receive the mixture of pulp suspension and concentrated ozone solution, an arrangement for producing an ozonic gas, filtering means, pumps and ducts for connecting the plant parts. The arrangement for producing ozone is flow-connected with an absorption column for preparing the concentrated ozone solution and a mixing arrangement is provided for mixing the pulp suspension with the concentrated ozone solution.

Abstract: The centering device comprises a centering plate (23) mounted on a carrier member (21) for rotation about an axis parallel to the axis of the steam generator tubes and carrying two radial expansion fastening grippers (39), and a drive (22, 27, 28) for orientation of the plate (23) about its axis. The fastening grippers (39) are disposed on the plate in relative positions corresponding to openings provided in the tube plate (18) for the passage of the tubes (13).

Abstract: A fuel assembly includes an array of fuel rods and guide thimbles disposed in laterally spaced relation to one another. The guide thimbles have upper ends extending above the upper ends of the fuel rods. The fuel assembly also includes a top nozzle defined solely by a flat rectangular adapter plate having a main central portion and a peripheral portion surrounding and merging with the main central portion. The main central portion of the adapter plate has a plurality of attachment holes receiving the upper ends of guide thimbles for attachment of the adapter plate upon the guide thimble upper ends in spaced relation above the fuel rod upper ends. A first sest of holes are defined through one pair of diagonal corners of the adapter plate for use in attaching sets of spring assemblies directly to and upon the adapter plate for alignment along the peripheral portions thereof.

Abstract: A high intensity, high temperature UV Lamp reactor system for treating aqueous media on a continuous flow basis is provided.

Abstract: The concentrations of residual heavy metal contaminants in the particulate material in a slurry produced in a particulate material washing process are monitored on-line and can be used to control the washing process. In alternative embodiments of the invention, x-rays, thermal neutrons or laser beams are directed at the slurry as it flows through a flow cell to induce emission of secondary x-rays, gamma rays or light, respectively, characteristic of the heavy metal contaminants and constituents representative of the solids contents of the slurry. These characteristic energies are measured and used to determine the concentration in ppm of the residual heavy metal contaminants in the particulate material within the slurry.

Abstract: The invention relates to a process for the extraction of uranium (VI) and/or plutonium (IV) present in an acid aqueous solution by means of a mixture of N,N-dialkyl amides usable for the reprocessing of irradiated nuclear fuels.In (50 or 52) contacting takes place between an aqueous solution containing U(VI) and Pu(IV) and an organic solvent incorporating a mixture of two N,N-dialkyl amides, e.g. of formulas: ##STR1## and then by separating (in 50 or 52) the organic solvent containing either U(VI) and Pu(IV), or U(VI).

Abstract: A nuclear reactor having a chemical decontamination system is provided in which every piece of decontamination equipment which processes radioactive materials is located within the containment chamber of the nuclear reactor. This decontamination system therefore presents advantageous safety benefits over an outside of containment system in the unlikely event of a leak of radioactive materials from the decontamination system.

Abstract: A process for producing porous articles from metal powders. A slurry including metal powders is deposited on a horizontally moving surface. The slurry/moving surface combination is passed through an evaporating zone, a calender zone and a sintering zone to form the desired article. The article is then separated from the moving surface.

Abstract: Apparatus and a method for producing submicron and smaller metal alloy pacles using a main chamber having a longitudinal axis and a feeder for introducing a quantity of molten alloy under pulsed gas pressure in a direction generally radial to the axis. The feeder has a gas stream for forming metal droplets from said alloy. A gas accelerator directs axially flowing gas against the droplets from the feeder in the chamber. The accelerator directs the droplets in an axial direction to a substrate located along the axis and in the direction of flow from the accelerator to receive the droplets at a predetermined distance from the feeder, whereby the particles are produced.

Abstract: A process is disclosed for installing an elastomeric liner in a pressure vessel. The process comprises winding a tacky ribbon around an expandable mandrel, inserting it in the vessel shell, expanding the mandrel and optionally curing the wound ribbon.

Abstract: A process to produce a free flowing fine polymer powder is provided. The process comprises the steps of: providing a polymer cement comprising a polymer either melt or dissolved in a solvent to form a polymer cement; dispersing an antiblocking agent within a stream consisting of steam to form atomization steam; atomizing the polymer cement; contacting the atomized polymer cement with the atomization steam; and recovering polymeric particles. Polymeric particles so prepared have an average particle size of between 100 and 1000 microns. In a preferred embodiment, the polymers produced are rubbery polymers which are free flowing.