Method for manufacturing nuclear fuel rod cladding and corresponding nuclear fuel rod cladding

Abstract

The manufacturing method is intended for the production of a nuclear fuel rod cladding tube (4) comprising a substrate (14) covered with a protective coating (16). The manufacturing method includes supplying the substrate (14) and depositing the protective coating (16) onto the substrate (14) by physical deposition by cathode sputtering, by simultaneously performing several different techniques of physical deposition by cathode sputtering.

Description

Technical Field

[0001] The present invention relates to the field of nuclear fuel rod cladding tubes (hereinafter also referred to as "cladding tubes") intended to contain nuclear fuel.

Background Art

[0002] Nuclear fuel containing fissionable material is generally stored in a cladding tube that prevents dispersion of the nuclear fuel.

[0003] A nuclear fuel assembly used in a light water reactor or a heavy water reactor generally includes a bundle of nuclear fuel rods, each nuclear fuel rod includes a tubular cladding tube that contains nuclear fuel, and the cladding tube is sealed at each of its both ends by plugs.

[0004] The nuclear fuel rods are, for example, made of a zirconium-based alloy. Such zirconium-based alloys have high performance under normal operating conditions in a nuclear reactor.

[0005] However, they may reach their limits, especially from the perspective of temperature, during severe accident situations such as during a loss of coolant accident (LOCA).

[0006] During such events, the temperature inside the core of the nuclear reactor may exceed 800 °C, at which time the existing coolant is essentially in the form of steam.

[0007] This causes rapid deterioration of the nuclear fuel rod cladding tube, and hydrogen is released in particular, the cladding tube rapidly oxidizes, leading to its embrittlement and even fracture, and thus the release of nuclear fuel outside the cladding tube may occur.

[0008] It is possible to provide a cladding tube including a base material made of a zirconium-based alloy with a protective coating made of, for example, a chromium-based material.

[0009] Such protective coatings can generally increase the resistance of the cladding tube under normal conditions and accident conditions.

[0010] Such coated tubes can be manufactured by applying a protective coating to a substrate using physical vapor deposition.

[0011] However, the application techniques for such protective coatings are relatively slow, especially when the coating thickness is large.

[0012] For protective coatings on nuclear fuel cladding to be widely used at an industrial level, the ability to apply the protective coatings quickly is required. [Overview of the project] [Problems that the invention aims to solve]

[0013] One of the objectives of the present invention is to propose a rapidly implementable method for manufacturing nuclear fuel cladding tubes having a substrate coated with a protective coating. [Means for solving the problem]

[0014] For this purpose, the present invention proposes a method for manufacturing a nuclear fuel rod cladding tube including a substrate covered with a protective coating, comprising supplying the substrate and simultaneously performing several techniques of physical deposition by cathode sputtering, thereby depositing the protective coating onto the substrate by physical deposition by cathode sputtering.

[0015] By simultaneously implementing several different techniques of physical vapor deposition using cathode sputtering, it is possible to achieve high-speed deposition of protective coatings, resulting in protective coatings with excellent resistance to the external environment and superior adhesion to the substrate.

[0016] "Simultaneous" implementation means that different physical vapor deposition techniques are performed together and at the same time, i.e., within the same period.

[0017] The different techniques of simultaneous cathode sputtering physical deposition can be implemented by using at least one common cathode for at least two of the different techniques of simultaneous cathode sputtering physical deposition, and / or by using at least one dedicated cathode for only one of the different techniques of simultaneous cathode sputtering physical deposition.

[0018] Each physical vapor deposition technique is performed by applying an excitation signal to a bonded cathode, and this excitation signal has a periodic pattern, which is, for example, a plateau, a pulse, or a pulse train.

[0019] The combined implementation of several different physical deposition techniques using the same common cathode can be achieved, for example, by combining excitation signals that are emitted synchronously and simultaneously, such that each of their patterns is sequentially applied to the common cathode.

[0020] According to a particular embodiment, the manufacturing method includes one or more of the following features individually or in any technically possible combination: - At least two of the different techniques of physical deposition by cathode sputtering are performed simultaneously using a common cathode; - The manufacturing method includes applying a combined excitation signal to each common cathode corresponding to the superposition of at least two fundamental excitation signals, each fundamental excitation signal being formed in a periodic pattern corresponding to each of the cathode sputtering physical deposition techniques performed simultaneously using the common cathode, and the fundamental excitation signals being synchronized such that their respective patterns appear sequentially within the combined excitation signal; - Each basic excitation signal is generated by its respective excitation signal generator, and these basic excitation signals are synchronized and superimposed to form a combined excitation signal applied to the common cathode; - At least one of the simultaneous cathode sputtering physical deposition techniques is performed using a dedicated cathode by applying an excitation signal for the implementation of this physical deposition technique to the dedicated cathode; - Each of the simultaneous cathode sputtering physical deposition techniques is performed using a dedicated cathode by applying an excitation signal to this dedicated cathode for the purpose of performing the physical deposition technique; - The excitation signal for each dedicated cathode is generated by its respective excitation signal generator; - The physical deposition techniques performed simultaneously are selected from among unipolar or bipolar high-power impulse magnetron sputtering (HiPIMS), unipolar or bipolar direct current (DC) magnetron sputtering, unipolar or bipolar pulsed direct current (pulsed DC) magnetron sputtering, unipolar or bipolar medium-wave (MF) magnetron sputtering, and unipolar or bipolar radio frequency (RF) magnetron sputtering; - The base material is made of zirconium-based material, and / or the protective coating is made of chromium-based material; - The thickness of the protective coating at the end of the adhesion step is 5 μm to 30 μm, particularly 10 μm to 20 μm; - The substrate has a rotational shape around its central axis, and the manufacturing method includes rotating the substrate around its central axis during the bonding step; - The manufacturing method includes polarization of the substrate during coating application.

[0021] The present invention also relates to a nuclear fuel rod cladding tube including a substrate covered with a protective coating deposited on the substrate by physical deposition, which is achieved by simultaneously performing multiple different techniques of physical deposition by cathode sputtering.

[0022] The present invention also relates to an equipment for physical vapor deposition, which includes a chamber, at least one atmosphere control device for generating a dilute atmosphere in the chamber, at least one cathode, and an excitation device, and is configured to deposit a protective coating on a substrate introduced into the chamber by simultaneously implementing a plurality of different techniques of physical vapor deposition technology by means of cathode sputtering using the cathode.

[0023] According to a specific embodiment, the equipment individually or in any technically possible combination takes up and includes one or more of the following optional features: - The equipment includes at least one common cathode for simultaneously implementing at least two of the physical vapor deposition techniques by means of cathode sputtering that are simultaneously implemented. The excitation device is configured to generate a combined excitation signal of the common cathode corresponding to the superposition of several basic excitation signals. Each basic excitation signal has a periodic pattern corresponding to each of the physical vapor deposition techniques by means of cathode sputtering that are simultaneously implemented using the common cathode, and the basic excitation signals are combined such that their respective patterns appear sequentially within the combined excitation signal; - The equipment includes at least one dedicated cathode for implementing one of the physical vapor deposition techniques by means of cathode sputtering that are simultaneously implemented. The excitation device is configured to generate respective excitation signals for each dedicated cathode, and the excitation signals correspond to the physical vapor deposition technique by means of cathode sputtering associated with this dedicated cathode. - The equipment is configured for the polarization of the substrate during coating deposition.

[0024] The invention and its advantages will be better understood by considering the following description, which is provided only as a non-limiting example and is described with reference to the accompanying drawings.

Brief Description of the Drawings

[0025] [Figure 1] It is a schematic longitudinal sectional view of a nuclear fuel rod having a coated tube. [Figure 2]Figure 1 is a schematic cross-sectional view of the cladding of a nuclear fuel rod. [Figure 3] This is a schematic diagram of the equipment for coating a substrate by cathode sputtering physical deposition, including a common cathode for two simultaneous cathode sputtering physical deposition techniques. [Figure 4] The document includes a graph illustrating an embodiment of a combined excitation signal for cathode excitation for performing physical deposition by cathode sputtering. [Figure 5] The document includes a graph illustrating an embodiment of a combined excitation signal for cathode excitation for performing physical deposition by cathode sputtering. [Figure 6] This is a schematic diagram of another deposition facility for coating a substrate by physical vapor deposition using cathode sputtering, which includes two dedicated cathodes, each equipped for carrying out a different physical vapor deposition technique using cathode sputtering. [Modes for carrying out the invention]

[0026] Figure 1 illustrates a nuclear fuel rod 2 intended for use in light water reactors, particularly pressurized water reactors (PWRs) or boiling water reactors (BWRs), "VVER" type reactors, "RBMK" type reactors, or, for example, "CANDU" type heavy water reactors.

[0027] The nuclear fuel rod 2 has an elongated shape along its longitudinal axis A.

[0028] The nuclear fuel rod 2 includes a cladding tube 4 that houses the nuclear fuel.

[0029] The cladding tube 4 is tubular and extends along the longitudinal axis A.

[0030] The cladding tube 4 is closed by sealing each end with its respective plug 6.

[0031] Nuclear fuel takes the form of a stack of pellets 8 stacked axially inside a cladding tube 4, for example, with each pellet 8 containing fissile material. The stack of pellets 8 is also called a "fissile column."

[0032] The nuclear fuel rod 2 includes a spring 10 disposed inside the cladding tube 4 between the stack of pellets 8 and one of the plugs 6 to press the stack of pellets 8 toward the other plug 6. Preferably, a gap or plenum 12 exists between the stack of pellets 8 and the plug 6 on which the spring 10 rests.

[0033] Figure 2 is a cross-sectional view of the cladding tube 4.

[0034] The coated tube 4 includes a base material 14 which is provided with a protective coating 16.

[0035] The base material 14 is tubular and extends along the longitudinal axis A. In other words, the base material 14 is a straight pipe with the longitudinal axis A as its central axis.

[0036] The base material 14 has an outer diameter of, for example, 8 mm to 15 mm, particularly 9 mm to 13 mm, and / or a length of 1 m to 5 m, particularly 2 m to 5 m.

[0037] The base material 14 is made of pure zirconium or a zirconium-based alloy.

[0038] The term "pure zirconium" refers to a material containing at least 99% by weight of zirconium, while the term "zirconium alloy" refers to an alloy containing at least 95% by weight of zirconium.

[0039] The zirconium alloy is selected from one of the known alloys, such as M5, ZIRLO, E110, HANA, N36, Zircaloy-2, and Zircaloy-4.

[0040] The substrate 14 has an inner surface 14A facing inward and an outer surface 14B facing outward. The inner surface 14A defines a space for housing nuclear fuel. The outer surface 14B is on the opposite side of the inner surface 14A.

[0041] The protective coating 16 covers the outer surface 14B of the substrate 14.

[0042] The purpose of the protective coating 16 is to protect the outer surface 14B of the substrate 14 from the external environment. Without the protective coating 16, the outer surface 14B of the cladding tube 14 would be exposed to the external environment.

[0043] The protective coating 16 is made of, for example, a chromium-based material.

[0044] The term "chromium-based material" refers to pure chromium or chromium-based alloys. Pure chromium material, in this context, means a material containing at least 99% by weight of chromium. Chromium-based alloy, in this context, means an alloy containing at least 80% by weight of chromium.

[0045] The thickness of the protective coating 16 is preferably 5 μm to 30 μm, and particularly 10 μm to 20 μm.

[0046] A method for manufacturing a cladding tube 4 includes supplying a substrate 14 and simultaneously performing several techniques of physical deposition by cathode sputtering with different cathodes to deposit a protective coating 16 onto the substrate 14 by physical deposition.

[0047] Physical vapor deposition, which involves cathode sputtering a coating onto a substrate, is performed by generating an electric field using a cathode (or "target") placed in a chamber containing a dilute atmosphere formed by a neutral gas such as argon. This electric field causes a plasma to appear in the chamber containing charged particles (electrons, ions, etc.) and atoms that are deposited on the cathode under the action of the electric field and detach atoms from the cathode (i.e., the cathode is sputtered, giving rise to the term cathode sputtering). These atoms detached from the cathode are then deposited onto the substrate. Optionally, a reactive gas such as dinitrogen or dioxygen may be present in the dilute atmosphere.

[0048] Advantageously, physical deposition by cathode sputtering is carried out by magnetron sputtering.

[0049] Physical deposition of a coating on a substrate by magnetron cathode sputtering is performed by generating electric and magnetic fields using a cathode (composed of a "target" and a "magnetron") placed in a chamber containing a dilute atmosphere formed by a neutral gas such as argon. The electromagnetic field causes a plasma containing charged particles (electrons, ions, etc.) and atoms to appear in the chamber, which are deposited on the cathode under the action of the electromagnetic field and detach atoms from the cathode (i.e., the cathode is sputtered, from which the expression cathode sputtering arises). These atoms detached from the cathode then adhere to the substrate.

[0050] A magnetron includes, for example, one or more permanent magnets and / or one or more electromagnets.

[0051] By providing a magnetic field, the trajectory of charged particles reaching the cathode can be better controlled, thereby allowing for more precise control of the coating deposition rate, and in particular, enabling the achievement of higher coating deposition rates.

[0052] In the following, unless otherwise specified, the terms "adhesion technique" and "physical deposition technique" refer to cathode sputtering, and, if possible, physical deposition using a magnetron.

[0053] Therefore, the method for manufacturing the cladding tube 4 involves the simultaneous implementation of several different cathode sputtering physical deposition techniques to deposit the protective coating 16 onto the substrate 14.

[0054] The physical vapor deposition techniques are performed simultaneously, using at least one common cathode for at least two of the simultaneously performed physical vapor deposition techniques, and / or at least one dedicated cathode each used for performing only one of the simultaneously performed physical vapor deposition techniques.

[0055] Preferably, if several cathodes are used for the simultaneous implementation of different physical vapor deposition techniques, these cathodes are made of the same material.

[0056] In one embodiment, at least two of the different physical deposition techniques are performed simultaneously using a common cathode by applying a combination of excitation signals to this common electrode, where each of the fundamental excitation signals corresponds to one of the physical deposition techniques performed simultaneously using the common electrode.

[0057] Each fundamental excitation signal has, for example, a periodic pattern, which may be a plateau, a pulse, or a pulse train.

[0058] The combined excitation signal is obtained, for example, by emitting the basic excitation signals simultaneously and in a synchronized manner such that each pattern of the basic excitation signals appears sequentially within the combined excitation signal, where each pattern of the basic excitation signals is applied sequentially to the common cathode.

[0059] In a combinational excitation signal, the pattern of each fundamental excitation signal exists within a distinctly different time window from that of the other fundamental excitation signal patterns that make up the combinational excitation signal. Each fundamental excitation signal pattern, with the exception of the other fundamental excitation signal patterns, exists within a time window specific to that fundamental excitation signal.

[0060] Different fundamental excitation signal patterns cannot coexist simultaneously within a combinational excitation signal.

[0061] In one embodiment, the first physical vapor deposition technique and the second physical vapor deposition technique are performed simultaneously using a common cathode by applying a combined excitation signal corresponding to the superposition of the first basic excitation signal and the second basic excitation signal to the common cathode, where the first basic excitation signal corresponds to the first physical vapor deposition technique and the second basic excitation signal corresponds to the second physical vapor deposition technique, and the first and second basic excitation signals are synchronized in such a way that their respective basic patterns alternate within the combined excitation signal.

[0062] As illustrated in Figure 3, the cathode sputtering physical deposition equipment 20, configured for the simultaneous implementation of several different physical deposition techniques using a common cathode, and in particular for the simultaneous implementation of the first and second physical deposition techniques, is operated simultaneously using a common cathode.

[0063] The apparatus 20 includes a chamber 22 for housing one or more substrates 14, an atmosphere control device 24 for generating a dilute atmosphere within the chamber 22, a common cathode 26, and an excitation device 28 connected to the common cathode 26.

[0064] The atmosphere control device 24 includes, for example, a pump device 30 connected to the chamber 22 to generate a dilute atmosphere within the chamber 22, and a gas supply device 32 fluidly connected to the chamber 22 to provide a neutral gas such as argon and / or a reactive gas such as dinitrogen or dioxygen.

[0065] The excitation device 28 is configured to generate a combined excitation signal applied to the common cathode 26 in response to the superposition of basic excitation signals for the implementation of physical deposition technology.

[0066] Each physical deposition technique is performed by applying a fundamental excitation signal to a bonded cathode, where the fundamental excitation signal has a repeating periodic pattern, which may be, for example, a plateau, a pulse, or a pulse train.

[0067] The superposition of synchronous excitation signals is performed synchronously, so that each excitation signal pattern is applied sequentially to the cathode.

[0068] The excitation apparatus 28 is configured to simultaneously perform the first physical evaporation technique and the second physical evaporation technique using a common cathode 26.

[0069] The excitation device 28 includes, for example, a first generator 34 and a second generator 36 connected in parallel to a common cathode 26, the first generator 34 and the second generator 36 being configured to synchronously generate a first electrical signal for carrying out a first physical vapor deposition technique and a second electrical signal for carrying out a second physical vapor deposition technique, respectively.

[0070] The equipment 20 optionally includes a magnetic field generator 38 (or magnetron) configured to generate a magnetic field near the common cathode 26 for the implementation of a physical deposition technique by cathode sputtering called a "magnetron" using the common cathode 26.

[0071] The magnetic field generator 38 includes one or more permanent magnets and / or one or more electromagnets.

[0072] When the magnetic field generator 38 is active, the first and second physical deposition techniques performed simultaneously are physical deposition techniques using magnetron cathode sputtering.

[0073] During operation, the atmosphere control device 24 generates a dilute atmosphere in the chamber 22, and the excitation device 28 generates a combined excitation signal, which is applied to the common cathode 26 in such a way that physical deposition technology is carried out simultaneously using the common cathode 26.

[0074] In particular, in the example provided, the first generator 34 and the second generator 36 simultaneously generate a first basic excitation signal and a second basic excitation signal, where the first basic excitation signal and the second basic excitation signal are superimposed to generate a combined excitation signal.

[0075] If necessary, the magnetic field generator 38 generates a magnetic field near the common cathode 26.

[0076] Each of the simultaneously performed physical deposition techniques can be achieved in either unipolar or bipolar mode.

[0077] Subsequently, if accuracy is lacking, each physical deposition technique can be used in unipolar or bipolar mode.

[0078] The physical deposition techniques performed simultaneously are selected from, for example, unipolar or bipolar high-power impulse magnetron sputtering (HiPIMS), unipolar or bipolar direct current (DC) magnetron sputtering, unipolar or bipolar pulsed direct current (pulsed DC) magnetron sputtering, unipolar or bipolar medium-wave (MF) magnetron sputtering, and unipolar or bipolar radio frequency (RF) magnetron sputtering.

[0079] In one embodiment, the common cathode 26 is used for simultaneous physical deposition by unipolar or bipolar high-power impulse magnetron sputtering and unipolar or bipolar medium-wave (MF) magnetron sputtering.

[0080] Optionally, the equipment 20 is configured to polarize the substrate 14 during physical vapor deposition. Polarization of the substrate 14 allows for improvement of the quality and density of the deposition, particularly the deposited coating. Polarization of the substrate 14 is performed, for example, using a dedicated substrate 14 polarization generator. For example, the substrate 14 polarization generator is configured to apply a constant voltage to the substrate, such as a voltage of approximately 100V.

[0081] Figure 4 includes three graphs representing the first fundamental excitation signal S1, the second fundamental excitation signal S2, and the combination of the first and second fundamental excitation signals S1 and S2, and more specifically the combined excitation signal SC obtained as a result of superposition, with each graph showing the instantaneous output of the corresponding excitation signal as a function of time.

[0082] The first basic excitation signal S1 is configured to realize physical deposition technology using high-power impulse magnetron sputtering.

[0083] The first fundamental excitation signal S1 is periodic and based on a first pattern formed by the first pulse. Therefore, the first fundamental excitation signal S1 includes a first pulse that is repeated at a first frequency F1 and a first output P1.

[0084] The second fundamental excitation signal S2 is configured to realize physical deposition technology using medium-power magnetron sputtering.

[0085] The second fundamental excitation signal S2 is based on a second pattern formed by a series of identical second pulses that are periodic and have a second frequency F2 and a second output P2. Thus, the second fundamental excitation signal S2 includes a series of second pulses, each series of second pulses containing several identical consecutive pulses with a second frequency F2 and a second output P2.

[0086] Figure 4 shows only one sequence of the second pulses. The second fundamental excitation signal S2 contains several consecutive sequences of the second pulses.

[0087] Preferably, the first frequency F1 is strictly lower than the second period number F2, and / or the first output P1 is strictly higher than the second output P2.

[0088] The duration of the second pulse sequence of the second basic excitation signal S2 preferably corresponds to the duration between the first pulse and the next first pulse of the first basic excitation signal S1, and the interval between the second pulse sequence of the second basic excitation signal S2 and the next second pulse sequence preferably corresponds to the duration of the first pulse of the first basic excitation signal S1.

[0089] The first basic excitation signal S1 and the second basic excitation signal S2 are synchronized such that the first and second patterns alternate within the combined excitation signal SC.

[0090] As a result of the superposition of the first fundamental excitation signal S1 and the second fundamental excitation signal S2, a combined excitation signal SC is obtained, which includes a first pulse at the first output P1 and a sequence of second pulses at the second output P2 between each first pulse and the next first pulse.

[0091] In the combined excitation signal SC, the first and second patterns are formed sequentially, and the sequence is repeated periodically.

[0092] The combined excitation signal SC enables the simultaneous implementation of the first physical evaporation technique and the second physical evaporation technique.

[0093] In particular, a first pulse with a first frequency F1 at a first output P1 enables the implementation of a first physical deposition technique (physical deposition by high-power impulse magnetron sputtering), where the time interval between the first pulses is utilized to implement a second physical deposition technique (physical deposition by medium-wave magnetron sputtering) which requires a pulse at a second output P2 with a second frequency F2 higher than the first frequency F1 and a lower frequency than the first output P1.

[0094] In one embodiment, the common cathode 26 is used for simultaneous physical deposition by unipolar or bipolar high-power impulse magnetron sputtering (HiPIMS) and physical deposition by unipolar or bipolar direct current (DC) magnetron sputtering.

[0095] Figure 5 is similar to Figure 4, but differs in that a second fundamental excitation signal S2 is provided for the realization of physical deposition technology by DC magnetron sputtering.

[0096] The second fundamental excitation signal S2 is periodic and based on a second pattern having the shape of a second plateau at the second output P2. Thus, the second fundamental excitation signal S2 includes a plateau at the second output P2, the plateau is separated by an interval at zero output, and the plateau preferably has a longer duration than that of the interval.

[0097] The distance between intervals corresponds to the duration between the first pulses of the first fundamental excitation signal S1, and the duration of the intervals corresponds to the duration of the first pulse of the first fundamental excitation signal S1.

[0098] Preferably, the first output P1 is strictly higher than the second output P2.

[0099] As a result of the superposition of the first fundamental excitation signal S1 and the second fundamental excitation signal S2, a combined excitation signal SC is obtained that includes the first pulse at the first output P1, with a plateau of the second output P2 between each first pulse and the next first pulse.

[0100] In the combined excitation signal SC, the first and second patterns are formed sequentially, and the sequence is repeated periodically.

[0101] The combined excitation signal SC enables the simultaneous implementation of the first physical evaporation technique and the second physical evaporation technique.

[0102] In particular, a first pulse with a first frequency F1 at a first output P1 enables the implementation of a first physical deposition technique (physical deposition by high-power impulse magnetron sputtering), where the time interval between the first pulses is utilized to implement a second physical deposition technique (physical deposition by DC magnetron sputtering) which requires DC at a second output P2 lower than the first output P1.

[0103] In one embodiment, at least one or each of the simultaneously performed physical deposition techniques is carried out using a dedicated cathode by applying a specific excitation signal between the dedicated cathode and the substrate for the execution of only one physical deposition technique.

[0104] Each dedicated cathode is associated with only one physical deposition technique and is distinctly different from each other cathode, whether it is a dedicated cathode or a common cathode.

[0105] In one embodiment, the excitation signal for each dedicated cathode is generated by its respective excitation signal generator.

[0106] In this case, the excitation device 28 includes an excitation signal generator coupled to each dedicated cathode.

[0107] In one embodiment, a first physical vapor deposition technique is performed using a first dedicated cathode by applying a first specific excitation signal for performing the first physical vapor deposition technique to the first dedicated cathode, and simultaneously, a second physical vapor deposition technique is performed using a second dedicated cathode by applying a second specific excitation signal for performing the first physical vapor deposition technique to the second dedicated cathode.

[0108] The equipment 20 in Figure 6 differs from the equipment in Figure 3 in that, although its reference number linked to similar elements is retained, it includes a first dedicated cathode 26A for implementing a first physical vapor deposition technique by cathode sputtering, and a second dedicated cathode 26B, which is distinctly different from the first dedicated cathode 26A, for implementing a second physical vapor deposition technique that is different from the first physical vapor deposition technique.

[0109] Preferably, the first dedicated cathode 26A and the second dedicated cathode 26B are made of the same material.

[0110] The excitation device 28 is configured to simultaneously generate a first specific excitation signal applied to the first dedicated cathode 26A and a second specific excitation signal applied to the second dedicated cathode 26B.

[0111] As illustrated in Figure 6, the excitation device 28 includes, for example, a first generator 34 configured to generate a first specific excitation signal and connected to a first dedicated cathode 26A, and a second generator 36 configured to generate a second specific excitation signal and connected to a second dedicated cathode 24B.

[0112] During operation, the atmosphere control device 24 generates a dilute atmosphere in the chamber 22, and the excitation device 28 simultaneously generates a first specific excitation signal applied to the first dedicated cathode 26A and a second specific excitation signal applied to the second dedicated cathode 26B, thereby simultaneously performing the first physical vapor deposition technique and the second physical vapor deposition technique.

[0113] In particular, the first generator 34 and the second generator 36 simultaneously generate a first specific excitation signal and a second specific excitation signal, respectively, which are applied to the first dedicated cathode 26A and the second dedicated cathode 26B, thereby simultaneously performing the first physical vapor deposition technique and the second physical vapor deposition technique.

[0114] If necessary, the magnetic field generator 38 generates a magnetic field near the first dedicated cathode 26A and / or near the second dedicated cathode 26B.

[0115] The physical deposition techniques performed simultaneously are selected from, for example, unipolar or bipolar high-power impulse magnetron sputtering (HiPIMS), unipolar or bipolar direct current (DC) magnetron sputtering, and unipolar or bipolar medium-wave (MF) magnetron sputtering.

[0116] In one embodiment, the first dedicated cathode 26A is used for performing unipolar or bipolar high-power impulse magnetron sputtering (HiPIMS), and the second dedicated cathode 26B is used for performing unipolar or bipolar medium-wave (MF) magnetron sputtering.

[0117] In this case, the first specific excitation signal and the second specific excitation signal correspond to the first basic excitation signal S1 and the second basic excitation signal S2 in Figure 3, respectively.

[0118] In one embodiment, the first dedicated cathode 26A is used for performing unipolar or bipolar high-power impulse magnetron sputtering (HiPIMS), and the second dedicated cathode 26B is used for performing unipolar or bipolar direct current (DC) magnetron sputtering.

[0119] In this case, the first specific excitation signal corresponds to the first basic excitation signal S1 in Figure 3, and the second specific excitation signal is a constant continuous signal at the second output P2.

[0120] Preferably, during physical deposition, the substrate 14, which is tubular along its longitudinal axis A, is rotated around its longitudinal axis A. This ensures uniform adhesion on the circumference of the substrate 14.

[0121] For this purpose, the equipment 20 is configured to rotate the substrate 14 around its longitudinal axis A during physical deposition.

[0122] The present invention is not limited to the exemplary embodiments and variations described above.

[0123] As illustrated in Figures 3 and 6, it is possible to precisely perform two physical deposition techniques simultaneously using a common cathode or two dedicated cathodes.

[0124] More generally, the protective coating 16 is deposited by simultaneously performing one, two, or more physical deposition techniques by cathode sputtering using one or more common cathodes and / or one or more dedicated cathodes.

[0125] Therefore, the physical vapor deposition equipment 20 for achieving the deposition of the protective coating 16 includes at least one common cathode 26 and / or at least one dedicated cathode 26A, 26B, and the excitation device 28 can generate a combined excitation signal applied to each common cathode 26 and a specific excitation signal applied to each dedicated cathode 26A, 26B.

[0126] Each common cathode is used to perform a group of physical deposition techniques, including at least two physical deposition techniques.

[0127] Each group of physical vapor deposition techniques includes, for example, two physical vapor deposition techniques (which constitute a pair or set of physical vapor deposition techniques) or more than two physical vapor deposition techniques.

[0128] Each group of physical vapor deposition techniques is distinct from other possible groups of physical vapor deposition techniques, however, if possible, several groups of physical vapor deposition techniques may include at least one physical vapor deposition technique common to one or more other groups of physical vapor deposition techniques when each is performed simultaneously using its respective common cathode.

[0129] Each dedicated cathode is associated with its respective physical vapor deposition technology, while, if possible, at least one group of physical vapor deposition technologies is performed simultaneously with the physical vapor deposition technology associated with the dedicated cathode, it can correspond to one physical vapor deposition technology from one or more groups of physical vapor deposition technologies.

[0130] In one embodiment, the protective coating 16 is applied by simultaneously performing a first physical vapor deposition technique, a second physical vapor deposition technique, and a third different physical vapor deposition technique, where the first and second physical vapor deposition techniques are performed using a common cathode, and the third technique is performed using a dedicated cathode that is distinctly different from the common cathode.

[0131] In one embodiment, the protective coating 16 is applied by simultaneously performing a first physical vapor deposition technique, a second physical vapor deposition technique, and a third different physical vapor deposition technique, where the first and second physical vapor deposition techniques are performed using a first common cathode, and the first and third physical vapor deposition techniques are performed using a second common cathode that is distinctly different from the first common cathode.

[0132] In one embodiment, the protective coating 16 is applied by simultaneously performing a first physical vapor deposition technique, a second physical vapor deposition technique, and a third different physical vapor deposition technique, each using a first dedicated cathode, a second dedicated cathode, and a third dedicated cathode, respectively.

[0133] In one embodiment, the protective coating 16 is applied by simultaneously performing a first physical vapor deposition technique and a second physical vapor deposition technique, where the first and second physical vapor deposition techniques are performed using a common cathode, the first physical vapor deposition technique is performed using a first dedicated cathode distinct from the common cathode, and optionally, the second physical vapor deposition technique is performed using a second dedicated cathode distinct from the common cathode and the first dedicated cathode.

[0134] In the above-described embodiment, the first, second, and third physical deposition techniques performed simultaneously are selected from, for example, unipolar or bipolar high-power impulse magnetron sputtering (HiPIMS), unipolar or bipolar direct current (DC) magnetron sputtering, and unipolar or bipolar medium-wave (MF) magnetron sputtering.

[0135] The above-described embodiments can be combined to simultaneously implement the first, second, and third physical vapor deposition techniques.

[0136] Each of the first, second, and third physical vapor deposition techniques can be performed simultaneously using at least one common cathode and a dedicated cathode.

[0137] Furthermore, the present invention is applicable to substrates other than nuclear fuel rod cladding substrates.

[0138] When the substrate is rotationally symmetric about its longitudinal axis, physical vapor deposition is preferably carried out by rotating the substrate about its longitudinal axis to ensure uniform adhesion on the circumference of the substrate.

[0139] The present invention makes it possible to apply a protective coating to nuclear fuel rod cladding tubes quickly and in a manner more suitable for industrial-scale production.

[0140] The deposition speed of protective coatings using physical deposition technology with high-power impulse magnetron sputtering (HiPIMS) and simultaneously using another physical deposition technology such as cathode sputtering, including DC magnetron sputtering or medium-wave (MF) magnetron sputtering, is 2 to 4 times faster than the deposition speed using physical deposition technology with high-power impulse magnetron sputtering (HiPIMS) alone, while maintaining the same deposition quality.

[0141] In particular, by using at least one common cathode 26, the utilization time of the common cathode 26 can be maximized.

[0142] In particular, a common cathode 26 used for both the implementation of physical deposition techniques by high-power impulse magnetron sputtering (HiPIMS) and other physical deposition techniques by cathode sputtering such as direct current (DC) magnetron sputtering or medium-wave (MF) magnetron sputtering can be utilized with a higher utilization rate compared to when it is used solely for the implementation of physical deposition techniques by high-power impulse magnetron sputtering (HiPIMS).

[0143] The time interval between high-power pulses in physical deposition techniques using high-power impulse magnetron sputtering (HiPIMS) is actually used for carrying out the aforementioned other physical deposition techniques by cathode sputtering.

[0144] Combining several techniques of physical deposition by cathode sputtering makes it possible to enjoy benefits derived from the advantages of different techniques, particularly in terms of the roughness of the protective coating 16, the corrosion resistance of the protective coating 16, the density of the protective coating 16, and / or the adhesion of the protective coating 16 to the substrate 14.

[0145] Preferably, the protective coating 16 is applied such that the cladding tube 4 has one or more of the following features: - The roughness of the protective coating is 2 μm or less, especially 1 μm or less; - The corrosion resistance of the chromium-based protective coating 16 is such that the chromium oxide layer Cr2O3 is less than 1 μm thick after 5 years of use in the core of a reactor under normal (accident-free) operation; and / or - The density of the protective coating is over 98%.

[0146] Here, density refers to either the percentage of the theoretical density of the same dense material, or the theoretical density minus the porosity. A density of over 98% corresponds to a porosity of less than 2%.

[0147] The quality of the adhesive strength between the substrate 14 and the protective coating 16 is tested by performing a compression-induced expansion test known by the acronym EDC, which stands for "Expansion Due to Compression".

[0148] By combining several techniques of physical deposition using cathode sputtering, it becomes possible to reduce the overall size of the physical deposition equipment, resulting in a reduction in the number of cathodes required to achieve the desired productivity.

[0149] The table below shows the results of three examples provided as non-limiting examples and comparative examples.

[0150] [Table 1]

[0151] In the first embodiment (Embodiment 1), a single cathode is used to simultaneously perform physical deposition by high-power impulse magnetron sputtering (HiPIMS) and physical deposition by direct current (DC) magnetron sputtering by applying two superimposed signals to the cathode.

[0152] In the second embodiment (Embodiment 2), a single cathode is used to simultaneously perform physical deposition by high-power impulse magnetron sputtering (HiPIMS) and medium-wave (MF) magnetron sputtering by applying two superimposed signals to the cathode.

[0153] In the third embodiment (Embodiment 3), two cathodes are used simultaneously: one for simultaneous physical deposition by high-power impulse magnetron sputtering (HiPIMS), and the other for physical deposition by direct current (DC) magnetron sputtering. Each cathode receives an excitation signal corresponding to its respective physical deposition technique.

[0154] In the comparative example, the fourth example (Example 4), a single cathode is used to perform a single physical deposition technique, more particularly high-power impulse magnetron sputtering (HiPIMS).

[0155] The deposition rates obtained in the first, second, and third embodiments are 6 μm / h, 5.5 μm / h, and 7 μm / h, respectively, assuming that the deposition rate achieved by performing a single physical deposition technique by cathode sputtering is approximately 2 to 3 μm / h, as exemplified in the fourth embodiment where the deposition rate is 2 μm / h. [Explanation of symbols]

[0156] 2 nuclear fuel rods 4 Cladding tube 6 plugs 8 pellets 10 springs 12 Plenum 14 Base material 16 Protective coating

Claims

1. In a method for manufacturing a cladding tube (4) for a nuclear fuel rod, which includes a substrate (14) covered with a protective coating (16), - Supply of the base material (14), - By simultaneously performing several different physical deposition techniques using cathode sputtering, the adhesion of a protective coating (16) onto the substrate (14) by physical deposition using cathode sputtering, A manufacturing method that includes this.

2. The method according to claim 1, wherein at least two of the different techniques of physical deposition by cathode sputtering are performed simultaneously using a common cathode (26).

3. The manufacturing method according to claim 2, comprising applying a combined excitation signal (SC) corresponding to the superposition of at least two basic excitation signals (S1, S2) to each common cathode (26), wherein each basic excitation signal (S1, S2) is formed in a periodic pattern corresponding to each of the physical deposition techniques by cathode sputtering performed simultaneously using the common cathode (26), and the basic excitation signals (S1, S2) are synchronized such that their respective patterns appear sequentially within the combined excitation signal (SC).

4. The manufacturing method according to claim 3, wherein each basic excitation signal (S1, S2) is generated by each excitation signal generator, and the basic excitation signals (S1, S2) are synchronized and superimposed to form a combined excitation signal (SC) applied to the common cathode (26).

5. The manufacturing method according to any one of claims 1 to 4, wherein at least one of the physical deposition techniques by cathode sputtering performed simultaneously is performed using dedicated cathodes (26A, 26B) by applying an excitation signal for performing the physical deposition technique to the dedicated cathodes (26A, 26B).

6. The manufacturing method according to claim 1, wherein each of the simultaneously performed physical deposition techniques by cathode sputtering is carried out using the dedicated cathodes (26A, 26B) by applying an excitation signal to the dedicated cathodes (26A, 26B) for the purpose of carrying out the physical deposition technique.

7. The manufacturing method according to claim 5 or 6, wherein the excitation signals for each dedicated cathode (26A, 26B) are generated by their respective excitation signal generators (26A, 26B).

8. The manufacturing method according to any one of claims 1 to 7, wherein the physical deposition technique performed simultaneously is selected from unipolar or bipolar high-power impulse magnetron sputtering (HiPIMS), unipolar or bipolar direct current (DC) magnetron sputtering, unipolar or bipolar pulsed direct current (pulsed DC) magnetron sputtering, unipolar or bipolar medium-wave (MF) magnetron sputtering, and unipolar or bipolar radio frequency (RF) magnetron sputtering.

9. The manufacturing method according to any one of claims 1 to 8, wherein the base material (14) is made of a zirconium-based material and / or the protective coating (16) is made of a chromium-based material.

10. The manufacturing method according to any one of claims 1 to 9, wherein the thickness of the protective coating at the end of the adhesion step is 5 μm to 30 μm, particularly 10 μm to 20 μm.

11. The manufacturing method according to any one of claims 1 to 10, wherein the substrate has a rotational shape around a central axis, and the manufacturing method includes rotating the substrate (14) around a central axis during the adhesion step.

12. A manufacturing method according to any one of claims 1 to 11, comprising polarization of the substrate (14) during coating application.

13. A nuclear fuel rod cladding tube comprising a substrate (14) covered with a protective coating (16) deposited on the substrate by physical deposition, which is achieved by simultaneously performing multiple different techniques of physical deposition by cathode sputtering.

14. A physical vapor deposition apparatus comprising a chamber (22), at least one atmosphere control device (24) for generating a dilute atmosphere within the chamber (22), at least one cathode (26, 26A, 26B), and an excitation device (28), wherein the apparatus is configured to deposit a protective coating (16) onto a substrate (14) introduced into the chamber (22) by simultaneously performing multiple different techniques of physical vapor deposition by cathode sputtering using the cathodes (26, 26A, 26B).

15. The apparatus according to claim 14, comprising at least one common cathode (26) for simultaneously performing at least two of the physical deposition techniques by cathode sputtering performed simultaneously, wherein the excitation device (28) is configured to generate a combined excitation signal (SC) of the common cathode (26) corresponding to the superposition of several basic excitation signals (S1, S2), each basic excitation signal (S1, S2) having a periodic pattern corresponding to each of the physical deposition techniques by cathode sputtering performed simultaneously using the common cathode (26), and the basic excitation signals (S1, S2) are combined such that their respective patterns appear sequentially within the combined excitation signal (SC).

16. The apparatus according to claim 14 or 15, comprising at least one dedicated cathode (26A, 26B) for performing one of a simultaneous cathode sputtering physical deposition technique, wherein the excitation device is configured to generate a respective excitation signal for each dedicated cathode (26A, 26B), the excitation signals corresponding to a cathode sputtering physical deposition technique associated with the dedicated cathode.

17. The apparatus according to any one of claims 14 to 16, configured for polarization of a substrate (14) during coating application.

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