Abstract: A pressurizer is for a pressurized water nuclear power plant and it includes an upper cap provided with a tube; an end piece connected to the tube using a weld; and a sleeve protecting the weld, disposed inside the tube. The protective sleeve is mounted in a removable manner, such that the thermal sleeve is removed.

Abstract: A zirconium alloy that is resistant to shadow corrosion for a boiling water nuclear reactor fuel assembly component, the alloy being characterized in that: its composition in percentages by weight is as follows: Nb=0.4%-4.5% Sn=0.20%-1.7% Fe=0.05%-0.45% Fe+Cr+Ni+V=0.05%-0.45%, with Nb?9×[0.5?(Fe+Cr+V+Ni)] S=traces-400 ppm C=traces-200 ppm Si=traces-120 ppm O=600 ppm-1800 ppm the balance being Zr and impurities from processing; in that, during fabrication, after its last hot deformation, it is subjected to one or more heat treatments lying in the range 450° C. to 610° C. for a total duration of at least 4 h, with at least one cold rolling operation with a rolling ratio of at least 25%; and in that a final heat treatment operation is performed at a temperature in the range 450° C. to 610° C. for 1 minute to 20 hours. A fuel assembly component made of the alloy, a fuel assembly including the component, and the use thereof.

Abstract: A grid (13) for supporting nuclear fuel pencils (3) for a nuclear fuel assembly (1) comprising a peripheral belt (17), the peripheral belt (17) comprising on at least one of its edges (35, 37) guide fins (33) is disclosed. The edge (35, 37) of the peripheral belt (17) has between the adjacent guide fins (33) recesses (39) towards the inside of the grid (13). The invention is applicable, for example, to pressurized water reactors.

Abstract: A module including a casing extending in a longitudinal direction, a bundle of fuel rods encased in and supported by the casing and connector provided on the casing for connecting the casing side-by-side to the casing of at least one other module to obtain a nuclear fuel assembly having a channel box defined by the casings of the assembled modules and of larger cross-section than the casing of each of the assembled modules and a bundle of fuel rods of larger cross-section than that of each the assembled modules.

Abstract: A sealed stopper for an opening in a junction tubing between an enclosure and a pipe, including an attachment ring. The stopper includes a rigid lid and a sealing assembly borne by the lid including a passive annular gasket including at least one annular internal chamber, a first static annular gasket, a second static annular gasket and a flat gasket ensuring the seal of the opening of the tubing.

Abstract: The heat exchange assembly (1) for exchanging heat between a first and a second fluid comprises: a plurality of heat exchange modules (12) for exchanging heat between the first and second fluids, these being distributed about a central axis (X) and having opposing respective lateral faces (47); feed manifolds (14, 16) for feeding the modules (12) with primary and secondary fluid and collection manifolds (18, 20) for removing these fluids. At least some of the said manifolds (14, 16) or parts of the said manifolds (18) run between the modules (12), the said manifolds (14, 16) or parts of manifolds (18) flanking one and the same module (12) being positioned substantially symmetrically with respect to the mid-plane situated between the two lateral faces (47) of the said module (12) in such a way that the said manifolds (14, 16) or parts of manifolds (18) create substantially identical thermal stresses in the lateral faces (47) of the module (12).

Abstract: A method for measuring the neutron flux in the core of a nuclear reactor, the method including several steps recurrently performed at instants separated by a period, the method comprising at each given instant the following steps: acquiring a total signal by a cobalt neutron detector placed inside the core of the reactor; assessing a calibration factor representative of the delayed component of the total signal due to the presence of cobalt 60 in the neutron detector; assessing a corrected signal representative of the neutron flux at the detector from the total signal and from the calibration factor; assessing a slope representative of the time-dependent change of the calibration factor between the preceding instant and the given instant; the calibration factor at the given instant being assessed as a function of the calibration factor assessed at the preceding instant, of the slope, and of the time period separating the given instant from the preceding instant.

Abstract: A method for producing a wear-resistant and corrosion-resistant stainless steel part for a nuclear reactor is provided. This method comprises steps of providing a blank in stainless steel; shaping the blank; finishing the blank to form the part in stainless steel, the finishing step allowing the prevented onset or the removal of work hardness on the outer surface of the part; hardening the outer surface of the part via diffusion of one or more atomic species.

Abstract: A filter is provided which includes channels for circulation of coolant fluid through the filter, at least one channel extending along a channel centerline and includes an upstream section, a downstream section and an intermediate section extending between the upstream section and the downstream section and being enlarged relative to the upstream section and the downstream section. The filter also includes at least one separating member defining inside the intermediate section of the at least one channel an annular passage whose axis is substantially coaxial to the channel centerline in the intermediate section.

Abstract: A filter including a plurality of flow ducts extending in a longitudinal direction and each delimited between one pair of walls is provided. The filter includes deflectors protruding into each duct alternately from the pair of walls with overlapping in the longitudinal direction to define a zigzag shaped flow channel and provided with at least one set of holes aligned in the longitudinal direction to define through the overlapping deflectors a passage for accommodating a lower end pin of a fuel rod.

Abstract: The object of the present invention is a method for establishing so-called “mixed IN-CORE mappings”. Its essential purpose is to compensate a loss of density of a reference instrumentation, called “RIC instrumentation” (or “RIC system”), when a significant number of locations, initially used by the sensors of the RIC system, are occupied by fixed collectron-type rods. An obvious physical interest lies in the increase of the measurement density, and thus of the level of confidence, associated with the operating results deduced from the processing of these measurements. One application of the method according to the invention concerns a collectron-type detector calibration method placed inside a nuclear reactor core.

Abstract: A method of operating a power generator is provided. The method includes determining an amount of oxides on a heat transfer surface of the power generator as a function of a concentration of a noble metal substance in the oxides; and altering operation of the power generator when the amount of oxides on the heat transfer surface reaches a predetermined value. A method of operating a nuclear reactor is also provided.

Abstract: This bottom end-piece includes nozzles for directing the flow of water of the reactor along the lower ends of the fuel rods, the nozzles being arranged at nodes of the substantially regular network of the fuel rods, and an anti-debris device which delimits water flow channels. At least some of the water flow channels are arranged at nodes of the substantially regular network. Direction nozzles are arranged at least partially in the channels in order to delimit water passages therewith, and at least one water passage includes a first section and a second section which are mutually offset radially relative to the corresponding node of the network in order to form a baffle.

Abstract: A nuclear power plant is provided including a BWR, a reactor cooling system cooling the BWR, an HWC hydrogen injection system connected to the reactor cooling system and an alcohol injection system connected to the reactor cooling system. Methods for providing methanol and hydrogen are also provided.

Abstract: This invention applies optical sensing technology with an ultrasound inspection system to associate encoded position data with the inspection data. The compact electronics of the optical system can be attached to the inspection assembly to allow fully encoded position information to be associated with the ultrasonic, eddy current, or other nondestructive examination data without substantially impacting the overall envelope of the NDE inspection equipment. Moreover, because of the small size, the optical system can be used in tandem to monitor skew or twist of the inspection equipment with respect to the normal rectilinear transducer orientation. The inspection equipment position information is then coupled to the inspection data to provide data outputs equivalent to fully encoded multi-axis manipulator automated scans, but with less setup burden and equipment expense.

Abstract: This invention applies optical tracking technology with an ultrasound inspection system to associate recorded position data with the inspection data. The reference targets of the optical tracking system can be attached to the inspection assembly to allow fully recorded position information to be associated with the ultrasonic, eddy current, or other nondestructive examination data without substantially impacting the overall envelope of the NDE inspection equipment. Moreover, the optical tracking system can be used to monitor skew or twist of the inspection equipment with respect to the normal rectilinear transducer orientation. The inspection equipment position information is then coupled to the inspection data to provide outputs equivalent to fully encoded multi-axis manipulator automated scans, but with less setup burden and equipment expense.

Abstract: A method is provided for operating a nuclear reactor. The method includes operating the nuclear reactor for an initial cycle during which a core contains initial nuclear fuel assemblies; then operating the nuclear reactor for transition cycles, at least some of the initial nuclear fuel assemblies being progressively replaced, during the replacement steps preceding the transition cycles, with transition nuclear fuel assemblies or with plutonium-equilibrium nuclear fuel assemblies; and then operating the nuclear reactor for at least one plutonium equilibrium cycle during which the core contains only plutonium-equilibrium nuclear fuel assemblies.

Abstract: A method of evaluating at least one quantity relating to the distortion of a nuclear fuel assembly, the method including the following steps: the nuclear fuel assembly is placed in a volume of water bounded by an upper free surface; a camera is placed outside the volume of water, above the free surface; at least one image of at least one lateral face of the nuclear fuel assembly is taken; the at least one image is analyzed graphically and the at least one quantity relating to the distortion of the nuclear fuel assembly is deduced therefrom.

Abstract: The method comprises the steps of: partitioning the core in cubes to constitute nodes of a grid for computer implemented calculation, splitting the cubes into a first category and a second category, each cube of the first category being adjacent only to cubes from the second category so that the first category and second category of cubes constitute a checkerboard-like pattern, ordering the cubes of the first category and then the cubes of the second category, calculating neutron flux and/or thermohydraulics parameters by using an iterative solving procedure of at least one linear system and/or an eigensystem, the components of an iterant of the linear system and/or the eigensystem constituting the neutron flux and/or thermohydraulics parameters to be calculated, wherein, during the iterative solving procedure, calculations are conducted on the cubes of the first category then on the cubes of the second category.

Abstract: A computer implemented method for modelizing a nuclear reactor core, including the steps of: partitioning the core in cubes to constitute nodes of a grid for computer implemented calculation, calculating neutron flux by using an iterative solving procedure of at least one eigensystem, the components of an iterant of the eigensystem corresponding either to a neutron flux, to a neutron outcurrent or to a neutron incurrent, for a respective cube to be calculated. A control parameter is varied to impact a neutron eigenvalue ? through a perturbed interface current equation and drive the neutron eigenvalue ? towards 1.