Abstract: A method for simulating the fluid flow in a vessel of a nuclear reactor is provided. The reactor includes a core inside the vessel, the core including a lower plate, an upper plate and fuel assemblies extending between the plates, and having a volume axially delimited by first and second interfaces corresponding to the plates. The method includes computing, for the core volume, the fluid pressure and speed, from an initial value of the speed or pressure in the first interface and respectively in the second interface, and using the fluid mass, movement quantity and energy balance equations.

Abstract: A micro-alloyed austenitic stainless steel for hot forging is provided. The micro-alloyed austenitic stainless steel has the following composition in weight %: 16.0%?Cr?25.0%; 8.0%?Ni?25.0%; traces?Mo?6.0%; traces?C?0.08%; traces?Si?1.0%; traces?Mn?3.0%; traces?P 21 0.045%; traces?S?0.035%; traces?Cu?2.0%; traces?N?0.2%; traces?V?0.3%; traces?Ti?0.3%; traces?B?0.005%; traces?W?3.0%; 0.015%?Nb?0.100%, the remainder being iron and inevitable manufacturing impurities.

Abstract: An assembly is provided including a mobile structure including a main pipe equipped with a first end intended to be connected to a water supply and a second end intended to be connected to a circuit connected to the primary circuit of the reactor, and including between these two ends in the direction of circulation of the water, a pump, a water heating device, an injector for continuously injecting the powdered neutron-absorbing element into the water of the main pipe, a first mixer for mixing and dissolving powder with water and a controller driving and controlling the flow rate of the water and the flow rate of the powder injected.

Abstract: The present invention relates to a method for detecting the drop of a cluster in a pressurized-water nuclear reactor, comprising the steps of: detecting a negative time derivative of the neutron flux, and comparing the absolute value of said time derivative to a first threshold value (S1); triggering a time delay (?T) if said absolute value is greater than said threshold value (S1); detecting a positive time derivative of said neutron flux, and comparing the absolute value of said time-derivative to a second threshold value (S2); and triggering the emergency shutdown of the reactor if the absolute value of said positive time derivative of said flux becomes greater than said second threshold value (S2) during said time delay (?T).

Abstract: A handling system including a tool for lifting the container, wherein the lifting tool includes a lifting carrier to be suspended and a member for gripping the container comprising removable devices for fastening the container onto the gripping member. According to one aspect of the invention, the gripping member is mounted so that it may rotate on the lifting carrier about a substantially horizontal rotation axis when the lifting carrier is suspended.

Abstract: A treatment process for a zirconium alloy is provided. The process includes the following steps: a zirconium alloy ingot is prepared, the composition of which is: 0.40%?Nb?1.05%; traces?Sn?2%; (0.5Nb?0.25)%?Fe?0.50%; traces?Ni?0.10%; traces?(Cr+V)%?0.50%; traces?S?35 ppm; 600 ppm?O?2000 ppm, preferably 1200 ppm?O?1600 ppm; traces?Si?120 ppm; traces?C?150 ppm; the remaining being Zr and unavoidable impurities; the ingot undergoes at least one reheating and hot shaping step, and possibly a reheating and quenching step following a hot shaping step; optionally the hot-shaped ingot undergoes an annealing; the hot-shaped and possibly annealed ingot undergoes at least one cycle of cold rolling-annealing steps; the annealing of at least one of the cold rolling-annealing steps being performed at a temperature comprised between 600° C. and the lowest of either 700° C. or (710?20×Nb %)° C., and the annealings of the other cold rolling-annealing steps, if any, being performed at a temperature not higher than 600° C.

Abstract: The installation provided includes at least one structure for receiving and holding guide tubes and structural elements; a carriage movable parallel to the guide tubes; at least one welding tool; and displacement means for moving the welding tool, the displacement means connecting the pincer to the carriage and presenting at least six degrees of freedom.

Abstract: An anchor device and a nuclear facility comprising such an anchor device are provided. This anchor device comprises a female part and a male part, the female part comprising a groove extending along a longitudinal axis, the groove having a width which decreases longitudinally and a transverse section, the male part comprising a slider with a shape mating that of the groove and able to be longitudinally inserted into the groove, the transverse section of the groove being configured so as to prevent the extraction of the slider out of the groove transversely to the longitudinal axis. The anchor device comprises a locking device able to prevent the slider from longitudinally sliding out of the groove.

Abstract: A nuclear fuel assembly having varying spacing between fuel rods is provided. The nuclear fuel assembly includes a bundle of fuel rods. The fuel rods are arranged in a first lattice with a non-uniform pitch between the fuel rods in the lowermost section of the fuel assembly and in a second lattice with a uniform pitch between the fuel rods in the uppermost section of the fuel assembly.

Abstract: A fuel rod support insert for a nuclear fuel assembly spacer grid, a spacer grid and a nuclear fuel assembly are provided. The support insert is for a nuclear fuel assembly spacer grid comprising interlaced straps defining a lattice of cells for receiving fuel rods, the insert being adapted to be secured to the straps for extending in at least one cell. The insert extends along an axis intended to be parallel to that of a cell and comprises two axially spaced end portions for connecting the insert to the straps and at least one elongated blade-like spring extending axially between the end portions for supporting a fuel rod. The spring has a non-rectilinear cross-section in each plane perpendicular to the insert axis.

Abstract: A method is provided for manufacturing a bundle of plates for a heat exchanger made up of a stack of plates. The method includes reducing by machining the initial thickness of each plate by making at least at the periphery of the plate, at least one connecting shoe having a height greater than the thickness of the machined plate, forming on the central portion of the plate, corrugations, to be superposed pairwise on the plates, connecting the shoes in contact with the plates of each pair through a weld bead, superposing the pairs of plates and connecting the shoes in contact with the pairs of plates through a sealed weld bead by arranging a superposition of open or closed ends for alternate inflow or outflow of said fluid.

Abstract: A sealed stopper for an opening in a tubing for joining a chamber and a piping including a fastening ring is provided. The stopper includes a rigid bearing plate and a sealing member carried by the bearing plate, and includes a seal having a planar and flexible central portion with a reduced thickness extending below the bearing plate and a peripheral portion radially deformable by a central expander of the peripheral portion against the inner surface of the fastening ring.

Abstract: The rod contains substantially cylindrical oxide nuclear fuel pellets based on enriched uranium oxide. The H/D ratio of the height over the diameter of the pellets lies in the range 0.4 to 0.6. The initial diametral clearance between the pellets and the cladding does not exceed 200 ?m.

Abstract: A sintered fuel pellet for a water nuclear reactor fuel rod including a peripheral wall extending along a central axis and two end faces. At least one of the end faces includes at least a first chamfer extending from the peripheral wall towards the central axis with a first non-zero slope with respect to a plane perpendicular to the central axis and a second chamfer extending from the first chamfer towards the central axis with a second non-zero slope with respect to a plane perpendicular to the central axis, wherein the first slope is different from the second slope.

Abstract: A nuclear fuel cladding is provided. The nuclear fuel cladding includes a base cladding; and at least one nanomaterial layer deposited on a surface of the base cladding, the nanomaterial layer having an average grain size of between 5 to 400 nanometers. A method of manufacturing nuclear fuel cladding is also provided. The method includes depositing nanoparticles on a base cladding to form at least one nanomaterial layer, the nanoparticles having an average grain size of between 5 to 400 nanometers.

Abstract: A nuclear fuel assembly tie plate is provided. The nuclear fuel assembly tie plate is formed by intersecting strips delimiting between them tubular guide cells each for allowing a fuel rod to extend through the tie plate. The strips delimit between them tubular flow cells separate from the guide cells, each flow cell for allowing coolant flow through the tie plate. Guide cells and flow cells are arranged at nodes of a lattice defined by a repeating pattern comprising four corner nodes in a square lattice arrangement and a central node at the center of the four corner nodes, with one guide cell at each corner nodes, separated by a pair of parallel spaced strips intersecting a pair of parallel spaced strips, the two pairs of strips delimiting a four-walled central flow cell at the center node.

Abstract: A method of operating a nuclear reactor is provided. The method includes defining a layer increment of a deposit layer modeling a deposit on a heat transfer surface of the nuclear reactor; periodically updating a thickness of the deposit layer by adding the layer increment to the deposit layer; recalculating properties of the deposit layer after each layer increment is added to the deposit layer; determining a temperature related variable of the heat transfer surface as a function of the recalculated properties of the deposit layer; and altering operation of the nuclear reactor when the temperature related variable of the heat transfer surface reaches a predetermined value. A method of modeling a deposit on a heat transfer surface of a nuclear reactor is also provided.

Abstract: Method of stabilizing radium present in radium-containing effluent, in which the effluent and a metal chloride are mixed, then the previously obtained mixture is reacted with a sulfate ion to obtain effluent containing stabilized radium. The chloride can be a barium, strontium or lead chloride. The sulfate ion can be supplied by the addition of sulfuric acid, sulfuric anhydride, soluable sulfate or soluble sulfate salt. The method applies in particular to the treatment of solid radium-containing effluents or effluents containing substances in suspension coming from chemistry or metallurgy of zirconium or treatment of uranium-containing minerals.

Abstract: A method for manufacturing a bi-material sleeve is provided. The sleeve includes an annular outer sleeve and an annular inner sleeve bonded to each other. The bottom pouring of the outer sleeve is carried out in a casting space delimited by a wall of a first ingot mold and by an outer upwardly moveable wall of a second ingot mold concentric with the first. The moveable wall of the second ingot mold is raised so as to uncover the skin of the outer sleeve which has solidified thereagainst. The bottom pouring and the solidification of the inner sleeve are carried out in a casting space delimited by said skin and an inner stationary wall of said second ingot mold, the bonding of both sleeves being effected by diffusion between said sleeves. Forging and/or machining of one of said bonded sleeves are optionally carried out. A device for using this method and a sleeve produced by this method are also provided.

Abstract: A nuclear power plant with an improved cooling system using nanoparticles in solid or fluid form is provided. The nanoparticles are delivered in locations such as the cold leg accumulator and high and low pressure pumps of an emergency core cooling system. Motor driven valves and pressurization can aid in the delivery. Methods for providing the nanoparticles are also provided.