Abstract: A method for assisting with surveillance of an element of a nuclear reactor, said method being implemented by an electronic device, comprising the steps of training an artificial-intelligence algorithm; acquiring an image of the element; estimating, on the basis of the image and via the artificial-intelligence algorithm, whether a fault is present in the element; displaying the image of the element; and if at least one fault is estimated to be present, generating an alarm. In the estimating step, an input to the artificial-intelligence algorithm is an image of a region comprising the element, and an output is a level of confidence as regards an absence of fault in the element for said region. If the level of confidence is lower than a threshold, then a fault is estimated to be present. In the training step, only images of fault-free elements are inputted into the artificial-intelligence algorithm.

Abstract: A nuclear fuel assembly comprises nuclear fuel rods (4) extending along a longitudinal axis (L) and a support skeleton (6) configured to support the nuclear fuel rods (4). The support skeleton (6) includes two end pieces (8, 10), a plurality of guide tubes (12) connecting the end pieces (8, 10) to each other, and spacer grids (14) attached to the guide tubes (12), with each spacer grid (14) supporting the nuclear fuel rods (4). The nuclear fuel assembly further includes at least one reinforcement device (20) comprising at least one reinforcement plate (22) which is in contact with at least two of the guide tubes (12) and attached to one or more of the guide tubes (12) at attachment points (21). Each reinforcement plate (22) has at least two attachment points (21) that are offset relative to each other along the longitudinal axis (L).

Abstract: A maintenance method is applied to a nuclear reactor having a drive assembly for a control rod assembly. The drive assembly includes a casing for receiving a drive rod lifting mechanism and a sheath for receiving the drive rod. A first lip is at an upper end of the casing, and a second lip is at a lower end of the sheath. The lips are welded together forming a seal between the casing and said sheath. The method includes removing the lips via material removal; carrying out a maintenance operation on the control rod assembly; creating a welding surface by machining the upper end of the casing; and creating a leak-tight connection between the casing and the sheath by welding the created welding surface to a matching welding surface provided at the lower end of the sheath. A replacement sheath may be used instead of the original sheath.

Abstract: A radioactive sodium destruction facility includes a tank for storing liquid metallic sodium, located at a first level; a reaction vessel containing an aqueous solution; a sodium feed circuit comprising a sodium circulation member located at a second level higher than the first level, the circulation member having a suction in fluid communication with the tank and a discharge in fluid communication with the reaction vessel; an inert gas supply unit configured to supply the tank; a controller driving the sodium circulation member; and an inert gas supply unit configured to supply the tank; and a controller driving the supply unit to control a gas pressure in the tank, such that a pressure at the suction of the sodium circulation member is maintained within a predetermined range.

Abstract: An extraction device for extracting a nuclear fuel rod or a cluster rod comprises an attachment portion configured to be inserted into a sleeve of the rod through an end without an end plug, and a grip portion, the attachment portion comprising an elongated body along a longitudinal axis and at least one tooth projecting from the body, the or each tooth being configured to allow the attachment portion to be forcibly inserted into the sleeve axially, and to engage with the inner surface of the sleeve so as to prevent the attachment portion from being extracted from the sleeve.

Abstract: A tubular component for a pressurised-water nuclear reactor, has the following composition by weight: 0.8%?Nb?2.8%; traces?Sn?0.65%; 0.015%?Fe?0.40%; preferably 0.020%?Fe?0.35%; traces?C?100 ppm; 600 ppm?O?2300 ppm; preferably 900 ppm?O?1800 ppm; 5 ppm?S?100 ppm; preferably 8 ppm?S?35 ppm; traces?Cr+V+Mo+Cu?0.35%; traces?Hf?100 ppm; F?1 ppm; the remainder being zirconium and impurities resulting from production. The tubular component has an outer surface with a roughness Ra less than or equal to 0.5 ?m, obtained following a final mechanical polishing step. The outer surface has a roughness Rsk?1 in absolute value and a roughness Rku?10.

Abstract: A reactor (1) for hydrolysis of uranium hexafluoride comprises a tubular injector (9) comprising first (11), second (13) and third (15) concentric fluid circulation ducts intended to be connected respectively with a source of UF6, a source of inert gas and a source of water vapor. The tubular injector (9) is obtained by additive manufacturing.

Abstract: A debris filter configured for a nuclear fuel assembly bottom end part includes a lower nozzle (8) and the debris filter (18) is supported by the lower nozzle (8). The debris filter (18) has an inlet face (18A) and an outlet face (18B) opposed to the inlet face (18A), and comprises at least one filtering section (18D) that has a retention capacity that increases gradually or stepwise towards from the inlet face (18A) to the outlet face (18B).

Abstract: A method for operating a nuclear reactor comprises acquiring a plurality of quantities characterizing the operation of the nuclear reactor; and calculating at least one Departure from Nucleate Boiling Ratio using a deep neural network. The entries of the deep neural network are determined by using the acquired quantities. The deep neural network includes at least two hidden layers of at least five neurons each. The method further includes calculating the deviations between the at least one calculated Departure from Nucleate Boiling Ratio and a plurality of predetermined reference threshold values and formulating a control signal for a reactor control system by using the calculated deviations. The control signal is an automatic reactor shutdown or alarm. The method also includes emergency shutdown of the nuclear reactor or emission of an alarm signal if relevant.

Abstract: A conversion process for converting uranium hexafluoride into uranium dioxide includes the steps of hydrolysis of UF6 to uranium oxyfluoride (UO2F2) in a hydrolysis reactor (4) by reaction between gaseous UF6 and dry water vapour injected into the reactor (4), pyrohydrolysis of UO2F2 to UO2 in a pyrohydrolysis furnace (6) by reacting UO2F2 with dry steam and gaseous hydrogen (H2) injected into the furnace (6), extracting excess gas in the reactor (4) via a collecting device (50) comprising several filters (52), periodically cleaning the filters (52) by injecting a neutral gas into the filters (52) from the outside to the inside of the reactor (4) to remove powder stuck on the filters (52), and measuring the relative pressure in the reactor (4). The conversion method further includes carrying out point cleaning of the filters (52) when the relative pressure in the reactor (4) exceeds a predetermined point cleaning threshold.

Abstract: An installation for the conversion of uranium hexafluoride (UF6) to uranium dioxide (UO2) comprises a hydrolysis reactor (4) for the conversion of UF6 into uranium oxyfluoride powder (UO2F2), a pyrohydrolysis furnace (6) for converting the UO2F2 powder supplied by the reactor (4) into UO2 powder, a supply device (8) comprising reagent injection ducts (10) for the injection of UF6, water vapor or H2, and a control system (16) designed to control the supply device (8) so as to supply at least one of the reagent injection ducts (10) with a neutral gas during a shutdown or start-up phase of the conversion installation.

Abstract: A method is for monitoring a nuclear reactor comprising a core in which fuel assemblies are loaded, each assembly comprising nuclear fuel rods each including nuclear fuel pellets and a cladding surrounding the pellets. The method includes determining (100) at least one operating time limit (TFPPI) for the extended reduced power operation of the reduced power nuclear reactor, so as to avoid a rupture of at least one of the claddings, operating (102) the nuclear reactor at reduced power for an actual time strictly less than the time limit (TFPPI), and relaxing (104) at least one threshold for protecting the nuclear power plant as a function of a difference between the time limit (TFPPI) and the actual time.

Abstract: A welding torch includes a head (3) having a body (11) bearing an electrode (13); an electric power source (27); and a filler metal wire (17) and a wire guide (19) guiding the filler metal wire (17) to the electrode (13). The body (11) is obtained by additive manufacturing from an electrically conductive metal, and the electrode (13) is electrically connected to the electric power source (27) by the metal constituting the body (11). The wire guide (19) includes an insulating sheath (29) inside which the filler metal wire (17) moves, and the filler metal wire (17) is electrically insulated from the potential of the body (11) by the insulating sheath (29).

Abstract: A method of determination of a nuclear core loading pattern defining the disposition of fuel assemblies. The method includes defining at least one potential core loading pattern and calculating predictive bowing of the fuel assemblies at the end of the operation cycle for each potential core loading pattern. The calculation is carried out by an automatic learning algorithm trained on a training data set that includes a plurality of other core loading patterns. The set also includes, for each of the other core loading patterns, measurements of bowing of fuel assemblies at the end of operation cycle. The method also includes evaluating the at least one potential core loading pattern based on the predictive bowing calculations and at least one predetermined criteria. The method further includes selecting one of the potential core loading patterns based at least in part on the evaluating.

Abstract: A BWR fuel assembly is elongated along a fuel assembly axis and comprises a lower tie plate, an upper tie plate axially spaced from the lower tie plate, a bundle of fuel rods extending axially between the lower tie plate and the upper tie plate, and a tubular fuel channel extending from the lower tie plate to the upper tie plate with encasing the fuel rods. The fuel assembly comprises an interaction device mounted on the lower tie plate and configured to interact with the fuel channel. The interaction device has an inactive configuration and an active configuration.

Abstract: A CNC machining device (1) comprises a control console (3) and a CNC machine (5). A training assembly (33) for training operation of the CNC machining device includes a training control console (35) substantially identical to the control console (3) of the CNC machining device (1); a digital twin (36) of the CNC machine (5), comprising a simulator (37) configured to simulate the effect of commands from the training control console (35) on the CNC machine (5); and a display device (39) configured for a trainee to view the current state of the simulator (37).

Abstract: A method for converting uranium hexafluoride to uranium dioxide includes steps of hydrolysis of UF6 to uranium oxyfluoride (UO2F2) in a hydrolysis reactor (4) by reaction between gaseous UF6 and dry water vapour injected into the reactor (4), and pyrohydrolysis of UO2F2 to UO2 in a pyrohydrolysis furnace (6) by reaction of UO2F2 with dry water vapour and hydrogen gas (H2) injected into the furnace (6). The hourly mass flowrate of gaseous UF6 supplied to the reactor (4) is between 75 and 130 kg/h, the hourly mass flowrate of dry water vapour supplied to the reactor (4) for hydrolysis is between 15 and 30 kg/h, and the temperature inside the reactor (4) is between 150 and 250° C.

Abstract: A method comprises inserting the fuel rod (4) through the spacer grids (14) aligned along an assembling axis (A) with passing the fuel rod (4) through a lubrication chamber (30) aligned with the spacer grids (14) such that the lubrication chamber (30) is passed through by the fuel rod (4) before the insertion of the fuel rod (4) through one of the spacer grids (14), and circulating a lubrication fluid containing a gas and a lubricant in gaseous phase and/or mist form in the lubrication chamber (30). The lubrication fluid is injected in the lubrication chamber (30) at a temperature strictly higher than ambient temperature, such that lubricant deposits or condensates in liquid phase with forming a lubricant film on an external surface of the fuel rod (4) that is being inserted through said one of the spacer grids (14).

Abstract: A method for protecting a nuclear reactor includes reconstructing a maximum linear power density released among the fuel rods of the nuclear fuel assemblies of the core; calculating the thermomechanical state and the burnup fraction of the rods; calculating a mechanical stress or deformation energy density in the cladding of one of the rods by using the said reconstructed maximum linear power density, the calculated thermomechanical states and the calculated burnup fractions, by means of a meta-model of a thermomechanical code; comparing the calculated mechanical stress or the calculated deformation energy density with a respective threshold; and stopping the nuclear reactor if the calculated mechanical stress or the calculated deformation energy density exceeds the respective threshold.

Abstract: An operating facility (1) for operating a mine by in-situ leaching comprises a supply manifold (9) for supplying leach liquor to the injector well heads (3), a production manifold (15) configured to discharge leachate to a leachate treatment plant (17), a treatment manifold (19), a facility (20) for providing a treatment solution configured to inject the treatment solution into the treatment manifold (19) and/or into the supply manifold (9); and for each producing well, a production pipe (21) equipped with a production cut-off device (25) and a treatment pipe (23) equipped with a treatment cut-off device (27), fluidically connecting the corresponding producing well head (5) in parallel, respectively, to the production manifold (15) and to the treatment manifold (19).