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 method is provided for operating a nuclear reactor. The method includes operating the nuclear reactor for at least one plutonium equilibrium cycle during which the core contains plutonium-equilibrium nuclear fuel assemblies; subsequently, operating the reactor for transition cycles, at least some of the plutonium-equilibrium nuclear fuel assemblies being progressively replaced with transition nuclear fuel assemblies and then with uranium-equilibrium nuclear fuel assemblies; and then operating the nuclear reactor for at least one uranium equilibrium cycle.

Abstract: A photonic spectrometry device is provided. The photonic spectrometry device includes at least one sensor capable of detecting photons, at least one photon-emitting calibrating source having a reference spectral line, and processing means capable of providing, for the or each sensor, a measurement spectrum corresponding to the measurements, made by the or each sensor, of the radiation from a product during a time interval, and establishing, on the basis of the or each measurement spectrum, a net corrected spectrum according to a measured characteristic line corresponding to the or each calibrating source. The or each calibrating source is positioned outside the or each sensor.

Abstract: A debris filter for a nuclear reactor installation is provided. The debris filter comprises a plurality of plates arranged side-by-side in a spaced relationship and delimiting between them flow passages extending through the debris filter from a lower inlet face to an upper outlet face of the debris filter, each passage having an intermediate section offset with respect to an inlet section and an outlet section. At least one of the plates is formed with debris catching features distributed along the plate and protruding into at least one passage delimited by the plate.

Abstract: A device for turning a container about a turning axis is provided. The device includes a stationary holding member and two bearing members which are spaced apart along the turning axis on each side of a space for receiving a container, and which are capable of being used for bearing on the container while enabling the rotation of the container about the turning axis relative to the bearing members. The device includes a movable holding member that is mounted onto the stationary holding member so as to rotate about the turning axis, at least one bearing member being supported by the movable holding member while being mounted onto the movable holding member so as to rotate about the drive axis, the or each bearing member supported by the movable holding member not rotating about the turning axis relative to the stationary holding member when the movable holding member rotates about the turning axis relative to the stationary holding member.

Abstract: An ultrasonic probe for examining an object with ultrasound and a corresponding examination method are provided. The probe includes a plurality of emitter elements able to emit ultrasonic waves for emitting a focused ultrasonic beam into the object through an active area of a surface of the object, and a profilometer for determining the profile of the surface of the object and for controlling the emission of the ultrasonic beam depending on the determined profile. The profilometer includes an image-taking apparatus for taking at least one digital image of the active area and an image processing module able to determine the profile of the active area by analyzing the optical blurring of the or at least one image.

Abstract: A method for working on a defective heating element of a pressurizer comprising a tank lying flat along a longitudinal axis and elongate heating elements extending within the tank, and at least one spacer plate through which the heating elements pass and which is capable of maintaining a transverse spacing between the heating elements is provided. The method includes cutting at least one spacer plate around the heating element so as to detach said heating element from said spacer plate, and then extracting the heating element from the tank in one single piece.

Abstract: A large-capacity electrical energy storage device is provided. The electrical energy storage device includes a plurality of electrolytic cells and a four-quadrant charger/inverter. In each electrolytic cell, the negative electrode and the positive electrode are positioned opposite one another, the electrolytic cell comprising a device for rotating the negative electrode relative to the positive electrode around a rotation axis.

Abstract: A nuclear fuel assembly for a boiling water reactor is provided. The nuclear fuel assembly includes a base, a head and a bundle of full length fuel rods and partial length fuel rods. The bundle extends longitudinally between the base and the head, at least one partial length fuel rod having a lower end received in a housing provided in the base and delimited by a closed bottom larger than the lower end. The housing is further delimited by a peripheral wall surrounding the lower end and the partial length fuel rod rests freely on the bottom.

Abstract: The strip is of the type comprising a wall portion for delimiting a cell for receiving a fuel rod and allowing flow of a coolant upwardly through the spacer grid, a spring provided on the wall portion for biasing a fuel rod extending through the cell away from the wall portion, the spring being cut out in the strip and delimited by a slot and a motion limiter formed in the strip on the wall portion to limit motion of a fuel rod received in the cell towards the wall portion against action of the spring. According to one aspect of the invention, the motion limiter is located on an edge of the slot opposite the spring and defines a risen portion on the edge.

Abstract: A photonic spectrometry device is provided. The photonic spectrometry device comprises several identical spectrometers each spectrometer comprising a radiation sensor and being capable of providing a measurement spectrum corresponding to the measurements of the sensor during a time interval, the spectrometers being capable of performing measurements simultaneously on one same radiation-emitting product and of providing measurement spectra for one same time interval, and a processor capable of determining a net spectrum from each of the measurement spectra provided by the spectrometers for one same time interval, and of determining a global spectrum resulting from the summation of the net spectra determined for one same time interval.

Abstract: A method for operating a nuclear reactor in order to produce electricity, such that the reactor is controlled so that, during a transient power occurrence for at least one of: a linear power density of the nuclear fuel rod remains lower than a limit linear power density, the limit linear power density being greater than 430 W/cm, and a variation of linear power density of the nuclear fuel rod remains lower than a limit variation, the limit variation being greater than 180 W/cm.

Abstract: An assembly for detecting and measuring the fouling rate by deposits containing at least one ferromagnetic material, including a probe which can be continuously moved inside a tube and which has a body carrying on its outer surface at least one magnetized source for self-orientation of the body of the probe, at least three magnetic field emitters and at least three magnetic field detectors each positioned between two contiguous emitters.

Abstract: A device for the dry handling of nuclear fuel assemblies is provided. The device includes a transfer basket which can be connected to a lifter and which includes a gripper for gripping the fuel assembly to be transferred, the gripper being supported by a lift built into the basket; and an indexing table which can be placed on a cask and which comprises a positioner for positioning the basket over a slot in the cask.

Abstract: A method for surface processing at least a portion of a component of zirconium or hafnium alloy, including at least one operation of nanostructuring a surface layer of the alloy so as to confer on the alloy over a thickness of at least 5 ?m a grain size which is less than or equal to 100 nm, the nanostructuring being carried out at a temperature which is less than or equal to that of the last thermal processing operation to which the component was previously subjected during its production. Component of zirconium or hafnium alloy processed in this manner.

Abstract: A lifting beam is provided. The lifting beam includes a lower beam and an upper beam arranged above the lower beam; an arranger for arranging the beams in close and releasable engagement with one another; and systems for gripping the load. The gripping systems are kept in an open position when the beams are in engagement with one another, and in a closed position when an engager is released.

Abstract: A motor stand of a primary motor-driven pump unit of a pressurized water nuclear reactor comprises an upper flange and fixing means suited to ensure the fixing of transverse holding means of the said primary motor-driven pump unit, the said primary motor-driven pump unit comprising an electric motor having a lower flange suited to be integrated with the said upper flange of the said motor stand. The motor stand is characterized in that the said fixing means comprise an annular element resting on the said upper flange of the said motor stand suited to be flanged between the said upper flange of the said motor stand and the said lower flange of the said motor, the said fixing means comprising at least one radial excrescence in which there is arranged a space suited to receive the said holding means.

Abstract: A container for a non-irradiated nuclear fuel assembly including a single casing for receiving at least one nuclear fuel assembly, the casing being formed from an elongate tubular shell, the shell including a metallic internal layer delimiting at least one individual housing for receiving a nuclear fuel assembly, and a metallic external layer surrounding the internal layer, the shell being filled between its internal layer and its external layer, and from lids for closing the or each housing at the longitudinal ends of the shell.

Abstract: A grid including at least two meshed grid parts intended to be superposed in a longitudinal direction, each grid part extending in a transverse plane, and the grid parts being moveable one relative to the other in at least one transverse direction between an open configuration for the insertion of nuclear fuel rods in the longitudinal direction through the grid parts, and a closed configuration allowing each fuel rod inserted through the grid parts to be clamped transversely between the grid parts. According to one aspect of the invention, the grid includes elements for transversely immobilizing the grid parts in the closed configuration, the immobilizing elements being designed to engage as the superposed grid parts are moved closer together in the longitudinal direction.

Abstract: A method for simulating the flow of a fluid in a vessel of a nuclear reactor is provided. The nuclear reactor includes the vessel and a core inside the vessel, the core including nuclear fuel assemblies, each one extending in an axial direction, including nuclear fuel rods and a grid for maintaining the rods, and being spaced apart from another by a clearance between the grids in a transverse direction. This method for simulating a fluid flow in the vessel of a nuclear reactor includes determining of head loss coefficients in the core, and computing the fluid pressure and speed component(s) in the core using the equation: ?P=?K×V where P is the component of the fluid pressure, K is a matrix including the determined head loss coefficients, and V is a vector including the fluid speed component(s).