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WO2025083082A1 - Nuclear fuel rod cladding and method for producing such cladding - Google Patents

Nuclear fuel rod cladding and method for producing such cladding Download PDF

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Publication number
WO2025083082A1
WO2025083082A1 PCT/EP2024/079239 EP2024079239W WO2025083082A1 WO 2025083082 A1 WO2025083082 A1 WO 2025083082A1 EP 2024079239 W EP2024079239 W EP 2024079239W WO 2025083082 A1 WO2025083082 A1 WO 2025083082A1
Authority
WO
WIPO (PCT)
Prior art keywords
tube
nuclear fuel
reinforced
cladding
reinforcing fibers
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/EP2024/079239
Other languages
French (fr)
Inventor
Pierre Barberis
Thorsten Heinrich MARLAUD
Thomas Garnier
Yassine ADERKAOUI
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Areva NP SAS
Original Assignee
Framatome SA
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Framatome SA filed Critical Framatome SA
Publication of WO2025083082A1 publication Critical patent/WO2025083082A1/en
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21C—NUCLEAR REACTORS
    • G21C3/00—Reactor fuel elements and their assemblies; Selection of substances for use as reactor fuel elements
    • G21C3/02—Fuel elements
    • G21C3/04—Constructional details
    • G21C3/06—Casings; Jackets
    • G21C3/07—Casings; Jackets characterised by their material, e.g. alloys
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21C—NUCLEAR REACTORS
    • G21C3/00—Reactor fuel elements and their assemblies; Selection of substances for use as reactor fuel elements
    • G21C3/02—Fuel elements
    • G21C3/04—Constructional details
    • G21C3/06—Casings; Jackets
    • G21C3/10—End closures ; Means for tight mounting therefor
    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21C—NUCLEAR REACTORS
    • G21C3/00—Reactor fuel elements and their assemblies; Selection of substances for use as reactor fuel elements
    • G21C3/02—Fuel elements
    • G21C3/04—Constructional details
    • G21C3/16—Details of the construction within the casing
    • G21C3/20—Details of the construction within the casing with coating on fuel or on inside of casing; with non-active interlayer between casing and active material with multiple casings or multiple active layers
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E30/00—Energy generation of nuclear origin
    • Y02E30/30—Nuclear fission reactors

Definitions

  • Nuclear fuel rod cladding and method of manufacturing such a cladding
  • the present invention relates to the field of nuclear fuel claddings (hereinafter also referred to as "claddings”) intended to contain nuclear fuel, in particular nuclear fuel rod claddings, and their manufacturing method.
  • claddings nuclear fuel claddings
  • Nuclear fuel including fissile material is generally contained in a sealed sheath which prevents the dispersion of the nuclear fuel.
  • Nuclear fuel assemblies used in light water or heavy water reactors generally comprise a bundle of nuclear fuel rods, each nuclear fuel rod comprising a tubular cladding containing nuclear fuel, the cladding being closed at each of its two ends by a respective cap.
  • the cladding of nuclear fuel assemblies is made, for example, of zirconium-based alloys. Such zirconium-based alloys exhibit high performance under normal operating conditions in nuclear reactors.
  • LOCA loss of coolant accident
  • the temperature in the core of the nuclear reactor can reach more than 800°C and the coolant is mainly in the form of water vapor.
  • One of the aims of the invention is to propose a sheath which exhibits improved behavior under normal conditions and accident conditions, while exhibiting improved wear resistance.
  • the invention provides a nuclear fuel rod sheath, the sheath comprising a tube extending along a longitudinal axis and a tubular internal lining received inside the tube, the tube comprising at least one reinforced layer made from a composite material comprising a ceramic matrix reinforced with ceramic reinforcing fibers, the thickness of the tube being between 280 ⁇ m and 600 ⁇ m.
  • the ceramic fiber-reinforced ceramic matrix composite tube provides a cladding that is highly resistant, particularly in accident conditions. This reduces the risk of the cladding rupturing and, in turn, the release of nuclear fuel from the cladding.
  • a silicon carbide matrix reinforced with silicon carbide and/or carbon fiber reinforcement is particularly resistant.
  • the internal lining provided in the tube improves the seal and in particular prevents the release of fission gases outside the sheath.
  • the sheath comprises one or more of the following optional features, taken individually or in all technically possible combinations:
  • the tube comprises a single reinforced layer, the thickness of the tube being between 280 pm and 340 pm;
  • the tube comprises exactly two reinforced layers, the thickness of the tube being between 450 pm and 600 pm;
  • the ceramic matrix is made of silicon carbide and/or the ceramic reinforcing fibers are made of silicon carbide and/or carbon;
  • one or each reinforced layer is formed with filament winding of the ceramic reinforcing fibers
  • one or each reinforced layer is formed with filament winding of the ceramic reinforcing fibers without interlacing of the ceramic reinforcing fibers;
  • one or each reinforced layer is formed with filament winding of the ceramic reinforcing fibers with interlacing of the ceramic reinforcing fibers, for example by braiding the ceramic reinforcing fibers;
  • the tube comprises at least one unreinforced layer, preferably made of the same material as the ceramic matrix;
  • the tube is formed exclusively from the ceramic matrix and ceramic reinforcing fibers
  • the internal lining has a thickness of between 50 pm and 200 pm, in particular between 50 pm and 150 pm;
  • the internal lining is metallic; - the internal lining is made of pure zirconium or a zirconium-based alloy containing at least 95% by weight of zirconium;
  • the sheath comprises an external protective layer covering an external surface of the tube
  • the outer protective layer is metallic
  • the outer protective layer is made of pure chromium or a chromium-based alloy containing at least 85% by weight of chromium or of pure zirconium or a zirconium-based alloy containing at least 85% by weight of zirconium or of pure titanium or a titanium-based alloy containing at least 80% by weight of titanium;
  • the outer protective layer has a thickness between 5 pm and 40 pm.
  • the invention also relates to a nuclear fuel rod comprising a cladding according to any one of the preceding claims, nuclear fuel received inside the inner lining of the cladding, and two plugs, each plug closing a respective axial end of the cladding.
  • the nuclear fuel rod comprises one or more of the following optional features, taken individually or in all technically possible combinations:
  • each plug is made of composite material comprising a ceramic matrix reinforced with ceramic reinforcing fibers, in particular a silicon carbide matrix reinforced with silicon carbide and/or carbon reinforcing fibers;
  • the nuclear fuel rod comprises two internal sealing elements, each closing a respective end of the internal lining;
  • the gas contained in the internal lining is helium and/or the pressure of the gas inside the internal lining is equal to or less than 200 bars, preferably equal to or less than 100 bars, more preferably equal to or less than 20 bars.
  • FIG. 1 is a schematic longitudinal sectional view of a nuclear fuel rod illustrating a cladding of the nuclear fuel rod;
  • FIG. 2 is a schematic sectional view of the nuclear fuel rod of Figure 1, along II-II in Figure 1;
  • FIG. 3 is a graph showing a curve illustrating the evolution of the maximum tensile circumferential stress at the internal surface of a sheath tube of the nuclear fuel rod, depending on the thickness of the tube, under operating conditions;
  • FIG. 4 is a graph showing a curve illustrating the evolution of the maximum tensile circumferential stress at the internal surface of a nuclear fuel rod cladding tube, as a function of the tube thickness, during an inter-cycle cold shutdown.
  • Figure 1 illustrates an example of a nuclear fuel rod 2 intended for use in a light water reactor, in particular a pressurized water reactor (or PWR for “Pressurized Water Reactor”) or a boiling water reactor (or BWR for “Boiling Water Reactor”), a “VVER” type reactor, an “RBMK” type reactor, or a heavy water reactor, for example of the “CANDll” type.
  • Nuclear fuel rod 2 has the shape of an elongated rod along a longitudinal axis A.
  • the nuclear fuel rod 2 comprises a cladding 4 containing nuclear fuel.
  • the cladding 4 is tubular and extends along the longitudinal axis A.
  • the sheath 4 is for example closed at its axial ends by two plugs 6, each plug 6 closing a respective axial end of the sheath 4, preferably in a sealed manner.
  • each stopper 6 has a gripping finger 6A
  • Each gripping finger 6A allows the nuclear fuel rod 2 to be gripped, for example during the manufacture of the nuclear fuel rod 2, during the insertion of the nuclear fuel rod 2 into a nuclear fuel assembly, or for the extraction of the nuclear fuel rod 2 from a nuclear fuel assembly.
  • the nuclear fuel is, for example, in the form of a stack of pellets 8 stacked axially inside the cladding 4, each pellet 8 containing fissile material.
  • the stack of pellets 8 is also called a “fissile column”.
  • the nuclear fuel rod 2 comprises a spring 10 arranged inside the cladding 4, between the stack of pellets 8 and one of the plugs 6, to push the stack of pellets 8 towards the other plug 6.
  • a vacuum or plenum 12 is present between the stack of pellets 8 and the plug 6 on which the spring 10 rests.
  • the sheath 4 has, for example, an external diameter of between 8 mm and 15 mm, in particular between 9 mm and 13 mm, and/or a length of between 1 m and 5 m, in particular between 2 m and 5 m.
  • the sheath 4 comprises a tube 14 having an inner surface 14A and an outer surface 14B.
  • the inner surface 14A faces the inside of the tube 14 and the outer surface faces the outside of the tube 14.
  • the tube 14 extends along the longitudinal axis A.
  • the tube 14 is for example closed at its axial ends by the two plugs 6, each plug 6 closing a respective axial end of the tube 14, preferably in a sealed manner.
  • the tube 14 is at least partly made of a ceramic matrix composite material reinforced with ceramic reinforcing fibers.
  • Ceramic reinforcing fibers are, for example, made of carbon or silicon carbide (SiC), preferably of nuclear quality.
  • Nuclear-grade silicon carbide reinforcing fibers are silicon carbide fibers with high crystallinity and/or stoichiometric or quasi-stoichiometric, i.e. with a C/Si ratio in atomic percentage (at%) between 1.00 and 1.10 (i.e. 1.00 ⁇ C%at/Si%at ⁇ 1.10) and an oxygen content of less than 1 mass percent (mass%), in particular so-called third-generation silicon carbide fibers.
  • Such silicon carbide reinforcing fibers have a high radiation tolerance.
  • the ceramic matrix is for example made of silicon carbide.
  • the tube 14 is in this case made at least in part of a composite material with a ceramic matrix of silicon carbide reinforced with silicon carbide fibers (SiC/SiCf) or carbon fibers (SiC/Cf).
  • the sheath 4 comprises a tubular inner lining 18 received inside the tube 14.
  • the inner lining 18 is preferably in contact with the inner surface 14A of the tube 14.
  • the tube 14 is formed of one or more superimposed layers.
  • the superimposed layers are concentric.
  • the tube 14 comprises a reinforced layer 16 or several reinforced layers 16.
  • Each reinforced layer 16 is made from the composite material comprising the ceramic matrix reinforced with the ceramic reinforcing fibers.
  • Each reinforced layer 16 is made of the ceramic matrix composite material, for example silicon carbide (SiC), reinforced with ceramic reinforcing fibers, preferably silicon carbide (SiC) and/or carbon (C).
  • SiC silicon carbide
  • C carbon
  • the tube 14 comprises, for example, a single reinforced layer 16 or exactly two reinforced layers 16.
  • the thickness of the tube 14, taken between its internal surface 14A and its external surface 14B, is between 280 pm and 600 pm.
  • the provision of a single reinforced layer 16 makes it possible to obtain a sheath 4 having sufficient mechanical strength, while limiting the thickness of the sheath 4.
  • the provision of two superimposed reinforced layers 16 makes it possible to improve the mechanical strength of the sheath 4, while having a sheath 4 whose thickness is contained.
  • each reinforced layer 16 the reinforcing fibers are for example arranged in a two- or three-dimensional arrangement.
  • the reinforcing fibers of one or each reinforced layer 16 are for example deposited by filament winding (winding a wire under tension around a rotating mandrel).
  • the reinforcing fibers are for example wound helically around the longitudinal axis A, preferably making a winding angle ⁇ 0 of between 30° and 60° with the direction of the longitudinal axis A, in particular a winding angle ⁇ 0 of approximately 45° with the direction of the longitudinal axis A.
  • Filament winding is carried out without interlacing the reinforcing fibers, in particular without braiding the reinforcing fibers, and/or with interlacing the reinforcing fibers, for example with braiding the reinforcing fibers.
  • the reinforcing fibers are pre-coated with a fiber/matrix interphase (thin intermediate layer with a “mechanical fuse” role) before being incorporated into a ceramic matrix, for example by chemical vapor infiltration (or CVI). This improves the damage tolerance of the composite material of the tube 14.
  • the tube 14 comprises at least one unreinforced layer 20.
  • Each unreinforced layer 20 is preferably made in the ceramic matrix not reinforced by ceramic reinforcing fibers, or in other words in the same material as the ceramic matrix of the reinforced layer(s) 16 not reinforced by ceramic reinforcing fibers.
  • an unreinforced layer 20 in the same material as that of the matrix of the reinforced layers 16 allows good cohesion between the layers of the tube 14, and makes it possible to limit the constraints of thermal origin and linked to the differences in behavior under irradiation.
  • the tube 14 comprises for example an internal unreinforced layer 20 covering the reinforced layer(s) 16 on the side of the internal surface 14A of the tube 14, and preferably defining the internal surface 14A of the tube 14, and/or an external unreinforced layer 20 covering the reinforced layer(s) 16 on the side of the external face 14B of the tube 14, and preferably defining the external surface 14B of the tube 14.
  • Unreinforced inner and outer layers 20 make it possible to control the dimensions of the tube 14, in particular the inner diameter of the tube 14 and the outer diameter of the tube 14, and the surface conditions of the inner 14A and outer 14B surfaces of the tube 14, for example by machining and/or lapping the unreinforced layers 20 to form the inner 14A and outer 14B surfaces of the tube 14.
  • the tube 14 comprises two reinforced layers 16
  • the tube 14 comprises an intermediate unreinforced layer 20 interposed between the two reinforced layers 16.
  • the tube 14 is formed exclusively from the ceramic matrix and the ceramic reinforcing fibers.
  • the tube 14 comprises at least one reinforced layer 16 in which the ceramic matrix is reinforced by the ceramic reinforcing fibers, thereby forming a composite material, and, optionally, at least one unreinforced layer 20 made with the ceramic matrix not reinforced by the ceramic reinforcing fibers.
  • a method of manufacturing the tube 14 comprises, for example, producing the reinforced layer(s) 16 by filament winding the reinforcing fibers and then infiltrating the reinforcing fibers with the matrix, for example by chemical vapor infiltration, then depositing an internal non-reinforced layer 20 and/or an external non-reinforced layer 20, then, preferably, reworking the internal surface 14A and/or the external surface 14B of the tube 14, for example by machining and/or lapping.
  • the manufacturing method comprises, for example, producing a reinforced layer 16, then depositing the intermediate unreinforced layer 20 over said reinforced layer 16, then producing the other reinforced layer 16 over the intermediate unreinforced layer 20.
  • the thicknesses are taken radially relative to the longitudinal axis A.
  • the tube 14 has a thickness (E1 in Figure 2) taken between the internal surface 14A and the external surface 14B of the tube 14, including the reinforced layer(s) 16, and the possible non-reinforced layer(s) 20.
  • the tube 14 comprises a single reinforced layer 16, the thickness E1 of the tube 14 being between 280 ⁇ m and 340 ⁇ m.
  • the tube 14 comprises exactly two reinforced layers 16, the thickness E1 of the tube 14 being between 450 ⁇ m and 600 ⁇ m.
  • the inner liner 18 is preferably in contact with the inner surface 14A of the tube 14.
  • the sheath 4 is free of radial play between the tube 14 and the internal lining 18.
  • the inner lining 18 is preferably solid.
  • the inner lining 18 is fluid-tight, particularly gas-tight.
  • the internal lining 18 is for example metallic, i.e. made of metal.
  • the internal lining 18 is for example made of pure zirconium or of a zirconium-based alloy containing at least 95% by weight of zirconium.
  • pure zirconium refers to a material containing at least 99% zirconium by weight. The remainder of the material consists of unavoidable impurities.
  • the zirconium-based alloy is, for example, chosen from one of the known alloys such as M5, ZIRLO, E110, HANA, N36, Zr-2.5Nb, Zircaloy-2 and Zircaloy 4.
  • the inner lining 18 has a thickness (E2 in Figure 2) of between 50 pm and 200 pm, in particular between 50 pm and 150 pm.
  • the internal lining 18 is for example pre-oxidized in a controlled environment to optimize its sealing characteristics and/or permeability to gas such as tritium.
  • the pre-oxidized inner liner 18 is intentionally manufactured with an oxide layer.
  • the oxide layer is present on the inner liner 18 before the nuclear fuel rod is used, particularly in a nuclear reactor.
  • the sheath 4 and/or its caps 6 optionally comprise an external protective layer 22.
  • the protective layer 22 covers the external surface 14B of the tube 14.
  • the outer protective layer 22 is, for example, metallic.
  • the outer protective layer 22 is made of pure chromium or a chromium-based alloy containing at least 85% by weight of chromium or of pure zirconium or a zirconium-based alloy containing at least 85% by weight of zirconium or of pure titanium or a titanium-based alloy containing at least 80% by weight of titanium.
  • pure chromium refers to a material that contains at least 99% chromium by weight. The remainder of the material consists of unavoidable impurities.
  • pure titanium refers to a material that is at least 99% titanium by weight. The remainder of the material consists of unavoidable impurities.
  • the outer protective layer 22 has a thickness (E3 in Figure 2) of between 5 ⁇ m and 40 ⁇ m.
  • the sheath 4 preferably comprises two sealing elements 24 each closing a respective axial end of the internal lining 18, preferably in a fluid-tight manner, in particular gas-tight.
  • Each sealing element 24 is for example fixed to the internal lining 18 by being welded and/or brazed and/or glued and/or inserted by force at the corresponding axial end of the internal lining 18.
  • the gas is for example helium.
  • the pressure is advantageously equal to or less than 200 bars, preferably equal to or less than 100 bars, more preferably equal to or less than 20 bars.
  • the pressure is for example 15 bars.
  • each sealing element 24 is metallic.
  • each sealing element 24 is made of the same material as the inner liner 18, and is preferably welded thereto, and also, optionally, welded, brazed, glued and/or force-fitted.
  • the sealing elements 24 closing the internal lining 18 are for example distinct from the plugs 6 closing the axial ends of the tube 14.
  • each plug 6 is made of a composite material comprising a matrix reinforced with reinforcing fibers, in particular a ceramic matrix reinforced with reinforcing fibers, even more in particular a silicon carbide matrix reinforced with silicon carbide fibers.
  • Each plug 6 is for example fixed to the tube 14 by being brazed and/or glued and/or inserted by force and/or pinned at the corresponding axial end of the tube 14. In advantageous embodiments, each plug 6 is brazed or pinned and brazed.
  • this covers the tube 14 over its entire length, and preferably partially or completely covers each plug 6, in particular at the junction between the plug 6 and the tube 14.
  • the tube 14 and the internal lining 18 are for example manufactured separately, then the internal lining 18 is closed, its gas tightness preferably being checked, then the previously closed internal lining 18 is inserted into the tube 14.
  • the manufacturing method comprises manufacturing the tube 14, obtaining the inner lining 18, filling the inner lining 18 with nuclear fuel, for example by inserting the pellets 8 into the inner lining 18, closing the inner lining 18 at its axial ends using the sealing elements 24, preferably checking the gas tightness of the closed inner lining 18, inserting the filled and closed inner lining 18 into the tube 14, then closing the tube 14 at its axial ends by the plugs 6.
  • the manufacture of the tube 14 comprises the production of the reinforced layer(s) 16, in particular by filament winding of reinforcing fibers, for example on a cylindrical shape (or mandrel).
  • the filament winding is carried out without interlacing of reinforcing fibers and/or with interlacing of reinforcing fibers, for example by braiding.
  • the reinforcing fibers are, for example, impregnated before deposition by filament winding, for example by passing through an impregnation bath, and/or after their filament winding, for example by infiltration, in particular by chemical vapor infiltration.
  • the method of manufacturing the tube 14 comprises the production of a single reinforced layer 16 or exactly two reinforced layers 16.
  • the method of manufacturing the tube 14 comprises the deposition of an intermediate non-reinforced layer 20 between the two reinforced layers 16.
  • the manufacturing method comprises, for example, the production of a reinforced layer 16, then the deposition of an non-reinforced layer 20 on the reinforced layer 16, then the production of another reinforced layer over the non-reinforced layer 20 which is interposed between the two reinforced layers 16.
  • the production of the reinforced layer(s) 16 is followed by deposition of an internal non-reinforced layer 20 and/or an external non-reinforced layer 20.
  • the manufacturing method comprises the deposition of an external protective layer 22 on the external surface 14B of the tube, for example by very low pressure plasma spraying (or VLPPS for “Vacuum Low Pressure Plasma Spraying”) or by physical vapor deposition (or PVD for “Physical Vapor Deposition”).
  • the deposition of the external protective layer 22 is for example carried out when the internal lining 18 containing the fuel is present inside the tube 14, and preferably after the tube 14 has been closed using the plugs 6.
  • the tube 14 is formed into a cylindrical shape prior to inserting the filled and sealed inner liner 18 inside the tube 14.
  • the inner liner 18 is filled with nuclear fuel and closed at its axial ends by the sealing elements 24, then the tube 14 is formed around the inner liner 18.
  • the inner liner 18 serves as a form for the production of the tube 14.
  • the proposed sheath 4 exhibits improved behavior under normal conditions of use and in accident conditions.
  • the tube 14 made of ceramic matrix composite material reinforced with silicon carbide fibers makes it possible to obtain a cladding 6 which is very resistant, particularly in accident conditions. The risk of rupture from the release of nuclear fuel out of the sheath is therefore reduced.
  • a silicon carbide matrix reinforced with silicon carbide reinforcing fibers is particularly resistant.
  • the internal lining 18 provided in the tube 14 makes it possible to improve the sealing and in particular to prevent the release of fission gases outside the sheath 6.
  • a protective coating i.e. the external protective layer 22 covering the external surface of the tube 14 of the cladding 4, and preferably also on the plugs 6, makes it possible to limit the risk of hydrothermal corrosion by the fluid circulating in the nuclear reactor around the nuclear fuel rod 2.
  • a protective coating i.e. the external protective layer 22 covering the external surface of the tube 14 of the cladding 4, and preferably also on the plugs 6, makes it possible to limit the risk of hydrothermal corrosion by the fluid circulating in the nuclear reactor around the nuclear fuel rod 2.
  • it makes it possible to avoid or at least limit the erosion of the composite material of the tube 14 and/or to limit the release of silicon into the primary fluid (when the tube 14 contains silicon) and/or to avoid or at least limit deposits, in particular CRUD deposits (from the English “Chalk River Unidentified Deposits”).
  • the thickness E1 of the tube 14, between 280 pm and 340 pm if the tube 14 comprises a single reinforced layer 16 or between 450 pm and 600 pm if the tube 14 comprises exactly two reinforced layers 16, makes it possible to form a cladding 4 having dimensions (in particular internal diameter and external diameter) compatible with existing nuclear fuel pellets.
  • the thickness E1 of the tube 14 of between 280 pm and 340 pm if the tube 14 comprises a single reinforced layer 16 or between 450 pm and 600 pm if the tube 14 comprises exactly two reinforced layers 16 allows, with the tube 14 made at least partly of composite material, in particular of the SiC/SiCf or SiC/Cf type, a satisfactory compromise between heat transfer and mechanical strength in normal operation and in accidental operation, with good tolerance to damage that may be suffered by the sheath 4.
  • the lower limit of the thickness E1 of the tube 14 makes it possible to withstand stress and deformation levels observed during the use of the cladding 4 in a nuclear reactor, in normal or incident operating conditions.
  • the lower limit of the thickness E1 is configured to hold the tube 14 under mechanical tensile stress with an elongation greater than 0.3% of deformation and/or a stress level before rupture greater than 100 MPa.
  • the upper limit of the thickness E1 of the tube 14 makes it possible to ensure satisfactory heat transfer during use, between the nuclear fuel contained in the tube 14 and the heat transfer fluid circulating outside the tube 14 in a nuclear reactor in which a nuclear fuel assembly integrating the fuel rod 2 is inserted. Indeed, during use, a thermal gradient is established in the thickness of the tube 14 due to the thermal exchanges between the nuclear fuel contained in the cladding 4 and the heat transfer fluid circulating outside the cladding 4.
  • This thermal gradient leads to direct internal stresses, by thermal expansion, and indirect internal stresses, by establishing a swelling gradient under irradiation, in the thickness of the tube 14.
  • Figure 3 is a graph illustrating the evolution of the maximum tensile circumferential stress at the internal surface 14A of the tube 14 as a function of the thickness E1 of the tube 14 (curve C1), for normal or incident operating conditions in a nuclear reactor.
  • Figure 4 is a graph illustrating the evolution of the maximum tensile circumferential stress at the internal surface 14A of the tube 14 as a function of the thickness E1 of the tube 14 (curve C2) during an inter-cycle cold shutdown in a nuclear reactor.
  • the upper limit of the thickness E1 of the tube 14 makes it possible to limit the circumferential tensile stresses at the internal surface 14A of the tube 14 under normal and incident operating conditions in a reactor
  • the lower limit of the thickness E1 of the tube 14 makes it possible to limit the circumferential tensile stresses during cold shutdown phases of the nuclear reactor, for example between cycles.
  • the minimum and maximum limits of the thickness E1 of the tube 14 are chosen so that the circumferential tensile stresses remain lower than a target elastic tensile limit of the ceramic matrix composite material reinforced with ceramic fibers (in particular SiC/SiCf or SiC/Cf).
  • the target tensile yield strength is preferably equal to or greater than 80 MPa.
  • an unreinforced layer 20 on the external face preferably having a micrometric surface condition, makes it possible to ensure protection of the reinforced layers 16 with respect to the exterior, in particular with respect to erosion/corrosion in contact with the heat transfer fluid circulating in a nuclear reactor in which a nuclear fuel assembly integrating the fuel rod 2 is inserted.
  • the total thickness of the reinforced layer(s) 16 is greater than 280 ⁇ m.
  • the total thickness of the reinforced layer(s) 16 is the sum of the thicknesses of the reinforced layers 16 of the tube 14.
  • the thickness of the unreinforced layer 20 on the external face is equal to or greater than 20 ⁇ m, in particular equal to or greater than 30 ⁇ m. This ensures the protection function of the reinforced layer(s) 16 of the heat transfer fluid.
  • the tube 14 closed at its axial ends by the plugs 6 and, preferably provided with the external protective layer 22, protects the internal lining 18 from the external environment under normal operating conditions and under accident conditions.
  • the thickness range provided for the internal lining 18 allows sufficient mechanical strength before insertion into the tube 14, limited neutron absorption and satisfactory heat transfer.
  • the internal lining 18 ensures gas tightness with limited impact on the internal diameter of the sheath 4.
  • the liner material 18 must have low interaction with the tube material 14 and with the nuclear fuel for the temperature conditions of severe accident conditions.
  • the thickness range provided for the outer protective layer 22 allows limited neutron absorption and satisfactory heat transfer, and ensures a good service life, with a controlled risk of delamination. It makes it possible to produce an outer protective layer 22 which remains protective despite swelling of the tube 14 under irradiation, which is generally less than 2%.
  • the total thickness of the sheath 4, comprising the tube 14, the internal lining 18, and optionally the external protective layer 22, is equal to or less than 600 ⁇ m, in particular equal to or less than 570 ⁇ m.
  • the total thickness of the sheath 4, comprising the tube 14, the internal lining 18, and optionally the external protective layer 22 corresponds to the sum of the thicknesses E1 (tube 14), E2 (internal lining 18) and E3 (external protective layer 22) in Figure 2.
  • a nuclear fuel rod may be provided for use in a nuclear fuel assembly comprising a bundle of fuel rods parallel nuclear arrays arranged in an NxN matrix configuration, N being an integer, in particular a 17x17 or 14x14 matrix configuration.
  • the total thickness of the sheath 4 is for example limited according to the number N of the NxN matrix configuration.
  • the cladding 4 is configured for a nuclear fuel rod 2 for a nuclear fuel assembly comprising a bundle of parallel nuclear fuel rods arranged in a 17x17 matrix configuration, and the total thickness of the cladding 4 is equal to or less than 570 ⁇ m.
  • the cladding 4 is configured for a nuclear fuel rod 2 for a nuclear fuel assembly comprising a bundle of parallel nuclear fuel rods arranged in a 14x14 matrix configuration, and the total thickness of the cladding 4 is equal to or less than 600 ⁇ m.
  • Limiting the total thickness of the cladding 4 ensures the compatibility of the cladding 4 with the fuel pellets 8 and existing nuclear fuel assemblies.
  • the invention also relates to a nuclear fuel assembly comprising a bundle of parallel nuclear fuel rods arranged in an NxN matrix configuration, N being an integer, in particular a 17x17 or 14x14 matrix configuration, each rod having a cladding, the claddings of the nuclear fuel rods being as defined above.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Plasma & Fusion (AREA)
  • General Engineering & Computer Science (AREA)
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Abstract

The invention relates to cladding comprising a tube (14) that extends along a longitudinal axis and a tubular inner lining (18) housed inside the tube (14), wherein the tube (14) comprises at least one reinforced layer (16) made of a composite material that comprises a ceramic matrix reinforced with ceramic reinforcing fibres, and wherein the thickness of the tube (14) is between 280 µm and 600 µm.

Description

Gaine de crayon de combustible nucléaire et procédé de fabrication d’une telle gaine Nuclear fuel rod cladding and method of manufacturing such a cladding

La présente invention concerne le domaine des gaines de combustible nucléaire (ci- après aussi nommées « gaines ») destinées à contenir du combustible nucléaire, en particulier des gaines de crayon de combustible nucléaire, et leur procédé de fabrication. The present invention relates to the field of nuclear fuel claddings (hereinafter also referred to as "claddings") intended to contain nuclear fuel, in particular nuclear fuel rod claddings, and their manufacturing method.

Le combustible nucléaire incluant la matière fissile est généralement contenu dans une gaine étanche qui évite la dispersion du combustible nucléaire. Nuclear fuel including fissile material is generally contained in a sealed sheath which prevents the dispersion of the nuclear fuel.

Les assemblages de combustible nucléaire utilisés dans les réacteurs à eau légère ou à eau lourde comprennent généralement un faisceau de crayons de combustible nucléaire, chaque crayon de combustible nucléaire comprenant une gaine tubulaire contenant du combustible nucléaire, la gaine étant fermée à chacune de ses deux extrémités par un bouchon respectif. Nuclear fuel assemblies used in light water or heavy water reactors generally comprise a bundle of nuclear fuel rods, each nuclear fuel rod comprising a tubular cladding containing nuclear fuel, the cladding being closed at each of its two ends by a respective cap.

Les gaines des assemblages de combustible nucléaire sont réalisées par exemple en alliage à base de zirconium. De tels alliages à base de zirconium présentent des performances élevées en conditions normales d’utilisation dans les réacteurs nucléaires. The cladding of nuclear fuel assemblies is made, for example, of zirconium-based alloys. Such zirconium-based alloys exhibit high performance under normal operating conditions in nuclear reactors.

Cependant, ils peuvent atteindre leurs limites notamment en termes de température lors de conditions accidentelles sévères, comme par exemple lors d’un accident de perte de fluide de refroidissement (ou LOCA pour « Loss Of Coolant Accident » en anglais). However, they can reach their limits, particularly in terms of temperature, during severe accident conditions, such as a loss of coolant accident (LOCA).

Lors d’un tel évènement, la température dans le cœur du réacteur nucléaire peut atteindre plus de 800°C et le fluide de refroidissement se présente essentiellement sous forme de vapeur d’eau. During such an event, the temperature in the core of the nuclear reactor can reach more than 800°C and the coolant is mainly in the form of water vapor.

Ceci peut causer une dégradation rapide de la gaine d’un crayon de combustible nucléaire, avec notamment un dégagement d’hydrogène et une oxydation rapide de la gaine conduisant à sa fragilisation voire à son éclatement, et donc au relâchement de combustible nucléaire hors de la gaine. This can cause rapid degradation of the cladding of a nuclear fuel rod, including the release of hydrogen and rapid oxidation of the cladding leading to its embrittlement or even its bursting, and therefore to the release of nuclear fuel from the cladding.

Un des buts de l’invention est de proposer une gaine qui présente un comportement amélioré en conditions normales et en conditions accidentelles, tout en présentant une résistance à l’usure améliorée. One of the aims of the invention is to propose a sheath which exhibits improved behavior under normal conditions and accident conditions, while exhibiting improved wear resistance.

A cet effet, l’invention propose une gaine de crayon de combustible nucléaire, la gaine comprenant un tube s’étendant suivant un axe longitudinal et une doublure interne tubulaire reçue à l’intérieur du tube, le tube comprenant au moins une couche renforcée réalisée dans un matériau composite comprenant une matrice céramique renforcée avec des fibres de renfort céramiques, l’épaisseur du tube étant comprise entre 280 pm et 600 pm. Le tube en matériau composite à matrice céramique renforcée de fibres céramiques permet d’obtenir une gaine qui est très résistante, notamment en conditions accidentelles. Le risque de rupture de la gaine et, ce faisant, de relâchement de combustible nucléaire hors de la gaine, est donc diminué. Par exemple, une matrice en carbure de silicium renforcée de fibres de renfort en carbure de silicium et/ou en carbone est particulièrement résistante. To this end, the invention provides a nuclear fuel rod sheath, the sheath comprising a tube extending along a longitudinal axis and a tubular internal lining received inside the tube, the tube comprising at least one reinforced layer made from a composite material comprising a ceramic matrix reinforced with ceramic reinforcing fibers, the thickness of the tube being between 280 μm and 600 μm. The ceramic fiber-reinforced ceramic matrix composite tube provides a cladding that is highly resistant, particularly in accident conditions. This reduces the risk of the cladding rupturing and, in turn, the release of nuclear fuel from the cladding. For example, a silicon carbide matrix reinforced with silicon carbide and/or carbon fiber reinforcement is particularly resistant.

La doublure interne prévue dans le tube permet d’améliorer l’étanchéité et en particulier d’empêcher le relâchement de gaz de fission hors de la gaine. The internal lining provided in the tube improves the seal and in particular prevents the release of fission gases outside the sheath.

Selon des modes de réalisation particuliers, la gaine comprend une ou plusieurs des caractéristiques optionnelles suivantes, prises individuellement ou selon toutes les combinaisons techniquement possibles : According to particular embodiments, the sheath comprises one or more of the following optional features, taken individually or in all technically possible combinations:

- le tube comprend une seule couche renforcée, l’épaisseur du tube étant comprise entre 280 pm et 340 pm ; - the tube comprises a single reinforced layer, the thickness of the tube being between 280 pm and 340 pm;

- le tube comprend exactement deux couches renforcées, l’épaisseur du tube étant comprise entre 450 pm et 600 pm ; - the tube comprises exactly two reinforced layers, the thickness of the tube being between 450 pm and 600 pm;

- la matrice céramique est réalisée en carbure de silicium et/ou les fibres de renfort céramiques sont réalisées en carbure de silicium et/ou en carbone ; - the ceramic matrix is made of silicon carbide and/or the ceramic reinforcing fibers are made of silicon carbide and/or carbon;

- une ou chaque couche renforcée est formée avec enroulement filamentaire des fibres de renfort céramiques ; - one or each reinforced layer is formed with filament winding of the ceramic reinforcing fibers;

- une ou chaque couche renforcée est formée avec enroulement filamentaire des fibres de renfort céramiques sans entrelacement des fibres de renfort céramiques ; - one or each reinforced layer is formed with filament winding of the ceramic reinforcing fibers without interlacing of the ceramic reinforcing fibers;

- une ou chaque couche renforcée est formée avec enroulement filamentaire des fibres de renfort céramiques avec entrelacement des fibres de renfort céramiques, par exemple par tressage des fibres de renfort céramiques ; - one or each reinforced layer is formed with filament winding of the ceramic reinforcing fibers with interlacing of the ceramic reinforcing fibers, for example by braiding the ceramic reinforcing fibers;

- le tube comprend au moins une couche non renforcée, réalisée de préférence dans le même matériau que la matrice céramique ; - the tube comprises at least one unreinforced layer, preferably made of the same material as the ceramic matrix;

- la gaine comprend une couche non renforcée interne recouvrant la ou les couches renforcées du côté de la face interne du tube et/ou une couche non renforcée externe recouvrant le ou les couches renforcées du côté de la face externe du tube et/ou une couche non renforcée intermédiaire intercalée entre deux couches renforcées du tube ; - the sheath comprises an internal unreinforced layer covering the reinforced layer(s) on the internal face side of the tube and/or an external unreinforced layer covering the reinforced layer(s) on the external face side of the tube and/or an intermediate unreinforced layer interposed between two reinforced layers of the tube;

- le tube est formé exclusivement de la matrice céramique et des fibres de renfort céramique ; - the tube is formed exclusively from the ceramic matrix and ceramic reinforcing fibers;

- la doublure interne présente une épaisseur comprise entre 50 pm et 200 pm, en particulier entre 50 pm et 150 pm ; - the internal lining has a thickness of between 50 pm and 200 pm, in particular between 50 pm and 150 pm;

- la doublure interne est métallique ; - la doublure interne est réalisée en zirconium pur ou en un alliage à base de zirconium contenant au moins 95% en poids de zirconium ; - the internal lining is metallic; - the internal lining is made of pure zirconium or a zirconium-based alloy containing at least 95% by weight of zirconium;

- la doublure interne est pré-oxydée ; - the internal lining is pre-oxidized;

- la gaine comprend une couche externe de protection recouvrant une surface externe du tube ; - the sheath comprises an external protective layer covering an external surface of the tube;

- la couche externe de protection est métallique ; - the outer protective layer is metallic;

- la couche externe de protection est réalisée en chrome pur ou en alliage à base de chrome contenant au moins 85% en poids de chrome ou en zirconium pur ou en alliage à base de zirconium contenant au moins 85% en poids de zirconium ou en titane pur ou en alliage à base de titane contenant au moins 80% en poids de titane ; - the outer protective layer is made of pure chromium or a chromium-based alloy containing at least 85% by weight of chromium or of pure zirconium or a zirconium-based alloy containing at least 85% by weight of zirconium or of pure titanium or a titanium-based alloy containing at least 80% by weight of titanium;

- la couche externe de protection présente une épaisseur comprise entre 5 pm et 40 pm. - the outer protective layer has a thickness between 5 pm and 40 pm.

L’invention concerne aussi un crayon de combustible nucléaire comprenant une gaine selon l’une quelconque des revendications précédentes, du combustible nucléaire reçu à l’intérieur de la doublure interne de la gaine, et deux bouchons, chaque bouchon fermant une extrémité axiale respective de la gaine. The invention also relates to a nuclear fuel rod comprising a cladding according to any one of the preceding claims, nuclear fuel received inside the inner lining of the cladding, and two plugs, each plug closing a respective axial end of the cladding.

Selon des modes de réalisation particuliers, le crayon de combustible nucléaire comprend une ou plusieurs des caractéristiques optionnelles suivantes, prises individuellement ou selon toutes les combinaisons techniquement possibles : According to particular embodiments, the nuclear fuel rod comprises one or more of the following optional features, taken individually or in all technically possible combinations:

- chaque bouchon est réalisé en matériau composite comprenant une matrice céramique renforcée de fibres de renfort céramiques, en particulier une matrice en carbure de silicium renforcée de fibres de renfort en carbures de silicium et/ou en carbone ; - each plug is made of composite material comprising a ceramic matrix reinforced with ceramic reinforcing fibers, in particular a silicon carbide matrix reinforced with silicon carbide and/or carbon reinforcing fibers;

- le crayon de combustible nucléaire comprend deux éléments internes d’obturation, fermant chacun une extrémité respective de la doublure interne ; - the nuclear fuel rod comprises two internal sealing elements, each closing a respective end of the internal lining;

- le gaz contenu dans la doublure interne est de l’hélium et/ou la pression du gaz à l’intérieur de la doublure interne est égale ou inférieure à 200 bars, de préférence égale ou inférieure à 100 bars, encore de préférence égale ou inférieure à 20 bars. - the gas contained in the internal lining is helium and/or the pressure of the gas inside the internal lining is equal to or less than 200 bars, preferably equal to or less than 100 bars, more preferably equal to or less than 20 bars.

L’invention et ses avantages seront mieux compris à la lecture de la description qui va suivre, donnée uniquement à titre d’exemple non limitatif, et faite en référence aux dessins annexés, sur lesquels : The invention and its advantages will be better understood upon reading the following description, given solely as a non-limiting example, and made with reference to the appended drawings, in which:

- la Figure 1 est une vue schématique en coupe longitudinale d’un crayon de combustible nucléaire illustrant une gaine du crayon de combustible nucléaire; - Figure 1 is a schematic longitudinal sectional view of a nuclear fuel rod illustrating a cladding of the nuclear fuel rod;

- la Figure 2 est une vue schématique en coupe du crayon de combustible nucléaire de la Figure 1 , selon II - Il sur la Figure 1 ; - Figure 2 is a schematic sectional view of the nuclear fuel rod of Figure 1, along II-II in Figure 1;

- la Figure 3 est un graphique présentant une courbe illustrant l’évolution de la contrainte circonférentielle en traction maximale à la surface interne d’un tube de la gaine du crayon de combustible nucléaire, en fonction de l’épaisseur du tube, en conditions de fonctionnement ; et - Figure 3 is a graph showing a curve illustrating the evolution of the maximum tensile circumferential stress at the internal surface of a sheath tube of the nuclear fuel rod, depending on the thickness of the tube, under operating conditions; and

- la Figure 4 est un graphique présentant une courbe illustrant l’évolution de la contrainte circonférentielle en traction maximale à la surface interne d’un tube de la gaine du crayon de combustible nucléaire, en fonction de l’épaisseur du tube, au cours d’un arrêt à froid inter-cycles. - Figure 4 is a graph showing a curve illustrating the evolution of the maximum tensile circumferential stress at the internal surface of a nuclear fuel rod cladding tube, as a function of the tube thickness, during an inter-cycle cold shutdown.

La Figure 1 illustre un exemple d’un crayon de combustible nucléaire 2 destiné à être utilisé dans un réacteur à eau légère, en particulier un réacteur à eau sous pression (ou PWR pour « Pressurized Water Reactor ») ou un réacteur à eau bouillante (ou BWR pour « Boiling Water Reactor »), un réacteur de type « VVER », un réacteur de type « RBMK », ou un réacteur à eau lourde, par exemple de type « CANDll ». Figure 1 illustrates an example of a nuclear fuel rod 2 intended for use in a light water reactor, in particular a pressurized water reactor (or PWR for “Pressurized Water Reactor”) or a boiling water reactor (or BWR for “Boiling Water Reactor”), a “VVER” type reactor, an “RBMK” type reactor, or a heavy water reactor, for example of the “CANDll” type.

Le crayon de combustible nucléaire 2 présente la forme d’une tige allongée suivant un axe longitudinal A. Nuclear fuel rod 2 has the shape of an elongated rod along a longitudinal axis A.

Le crayon de combustible nucléaire 2 comprend une gaine 4 contenant du combustible nucléaire. La gaine 4 est tubulaire et s’étend suivant l’axe longitudinal A. The nuclear fuel rod 2 comprises a cladding 4 containing nuclear fuel. The cladding 4 is tubular and extends along the longitudinal axis A.

La gaine 4 est par exemple fermée à ses extrémités axiales par deux bouchons 6, chaque bouchon 6 fermant une extrémité axiale respective de la gaine 4, de préférence de manière étanche. The sheath 4 is for example closed at its axial ends by two plugs 6, each plug 6 closing a respective axial end of the sheath 4, preferably in a sealed manner.

Un des deux bouchons 6 ou, de préférence, chaque bouchon 6 possède un doigt de préhension 6A One of the two stoppers 6 or, preferably, each stopper 6 has a gripping finger 6A

Chaque doigt de préhension 6A permet la préhension du crayon de combustible nucléaire 2, par exemple lors de la fabrication du crayon de combustible nucléaire 2, lors de l’insertion du crayon de combustible nucléaire 2 dans un assemblage de combustible nucléaire, ou encore pour l’extraction du crayon de combustible nucléaire 2 hors d’un assemblage de combustible nucléaire. Each gripping finger 6A allows the nuclear fuel rod 2 to be gripped, for example during the manufacture of the nuclear fuel rod 2, during the insertion of the nuclear fuel rod 2 into a nuclear fuel assembly, or for the extraction of the nuclear fuel rod 2 from a nuclear fuel assembly.

Le combustible nucléaire se présente par exemple sous la forme d’un empilement de pastilles 8 empilées axialement à l’intérieur de la gaine 4, chaque pastille 8 contenant du matériau fissile. L’empilement de pastilles 8 est aussi appelée « colonne fissile ». The nuclear fuel is, for example, in the form of a stack of pellets 8 stacked axially inside the cladding 4, each pellet 8 containing fissile material. The stack of pellets 8 is also called a “fissile column”.

Le crayon de combustible nucléaire 2 comprend un ressort 10 disposé à l’intérieur de la gaine 4, entre l’empilement de pastilles 8 et l’un des bouchons 6, pour pousser l’empilement de pastilles 8 vers l’autre bouchon 6. Un vide ou plenum 12 est présent entre l’empilement de pastilles 8 et le bouchon 6 sur lequel le ressort 10 prend appui. The nuclear fuel rod 2 comprises a spring 10 arranged inside the cladding 4, between the stack of pellets 8 and one of the plugs 6, to push the stack of pellets 8 towards the other plug 6. A vacuum or plenum 12 is present between the stack of pellets 8 and the plug 6 on which the spring 10 rests.

La gaine 4 présente par exemple un diamètre externe compris entre 8 mm et 15 mm, en particulier entre 9 mm et 13 mm, et/ou une longueur comprise entre 1 m et 5 m, en particulier entre 2 m et 5 m. Comme visible sur les Figures 1 et 2, la gaine 4 comprend un tube 14 présentant une surface interne 14A et une surface externe 14B. La surface interne 14A est tournée vers l’intérieur du tube 14 et la surface externe est tournée vers l’extérieur du tube 14. Le tube 14 s’étend suivant l’axe longitudinal A. The sheath 4 has, for example, an external diameter of between 8 mm and 15 mm, in particular between 9 mm and 13 mm, and/or a length of between 1 m and 5 m, in particular between 2 m and 5 m. As seen in Figures 1 and 2, the sheath 4 comprises a tube 14 having an inner surface 14A and an outer surface 14B. The inner surface 14A faces the inside of the tube 14 and the outer surface faces the outside of the tube 14. The tube 14 extends along the longitudinal axis A.

Le tube 14 est par exemple fermé à ses extrémités axiales par les deux bouchons 6, chaque bouchon 6 fermant une extrémité axiale respective du tube 14, de préférence de manière étanche. The tube 14 is for example closed at its axial ends by the two plugs 6, each plug 6 closing a respective axial end of the tube 14, preferably in a sealed manner.

Le tube 14 est au moins en partie réalisé en un matériau composite à matrice céramique renforcée de fibres de renfort céramiques. The tube 14 is at least partly made of a ceramic matrix composite material reinforced with ceramic reinforcing fibers.

Les fibres de renforts céramiques sont par exemple réalisées en carbone ou en carbure de silicium (SiC), de préférence de qualité nucléaire. Des fibres de renfort en carbure de silicium de qualité nucléaire sont des fibres en carbure de silicium à haute cristallinité et/ou stoechiométriques ou quasi-stœchiométriques, i.e. avec un rapport C/Si en pourcentage atomique (%at) compris entre 1 ,00 et 1 ,10 (soit 1 ,00 < C%at/Si%at < 1 ,10) et une teneur en oxygène inférieure à 1 pourcent massique (%mass), en particulier des fibres en carbure de silicium dites de troisième génération. De telles fibres de renfort en carbure de silicium présentent une forte tolérance aux irradiations. Ceramic reinforcing fibers are, for example, made of carbon or silicon carbide (SiC), preferably of nuclear quality. Nuclear-grade silicon carbide reinforcing fibers are silicon carbide fibers with high crystallinity and/or stoichiometric or quasi-stoichiometric, i.e. with a C/Si ratio in atomic percentage (at%) between 1.00 and 1.10 (i.e. 1.00 < C%at/Si%at < 1.10) and an oxygen content of less than 1 mass percent (mass%), in particular so-called third-generation silicon carbide fibers. Such silicon carbide reinforcing fibers have a high radiation tolerance.

La matrice céramique est par exemple réalisée en carbure de silicium. Le tube 14 est dans ce cas réalisé au moins en partie dans un matériau composite à matrice céramique en carbure de silicium renforcé de fibres de carbure de silicium (SiC/SiCf) ou de fibres de carbone (SiC/Cf). The ceramic matrix is for example made of silicon carbide. The tube 14 is in this case made at least in part of a composite material with a ceramic matrix of silicon carbide reinforced with silicon carbide fibers (SiC/SiCf) or carbon fibers (SiC/Cf).

La gaine 4 comprend une doublure interne 18 tubulaire reçue à l’intérieur du tube 14. La doublure interne 18 est de préférence en contact avec la surface interne 14A du tube 14. The sheath 4 comprises a tubular inner lining 18 received inside the tube 14. The inner lining 18 is preferably in contact with the inner surface 14A of the tube 14.

Le tube 14 est formé d’une couche ou de plusieurs couches superposées. Les couches superposées sont concentriques. The tube 14 is formed of one or more superimposed layers. The superimposed layers are concentric.

Le tube 14 comprend une couche renforcée 16 ou plusieurs couches renforcées 16.The tube 14 comprises a reinforced layer 16 or several reinforced layers 16.

Chaque couche renforcée 16 est réalisée dans le matériau composite comprenant la matrice céramique renforcée avec les fibres de renfort céramiques. Each reinforced layer 16 is made from the composite material comprising the ceramic matrix reinforced with the ceramic reinforcing fibers.

Chaque couche renforcée 16 est réalisée dans le matériau composite à matrice céramique, par exemple en carbure de silicium (SiC), renforcée de fibres de renfort céramique, de préférence en carbure de silicium (SiC) et/ou en carbone (C). Each reinforced layer 16 is made of the ceramic matrix composite material, for example silicon carbide (SiC), reinforced with ceramic reinforcing fibers, preferably silicon carbide (SiC) and/or carbon (C).

Le tube 14 comprend par exemple une seule couche renforcée 16 ou exactement deux couches renforcées 16. The tube 14 comprises, for example, a single reinforced layer 16 or exactly two reinforced layers 16.

L’épaisseur du tube 14, prise entre sa surface interne 14A et sa surface externe 14B, est comprise entre 280 pm et 600 pm. La prévision d’une seule couche renforcée 16 permet d’obtenir une gaine 4 présentant une tenue mécanique suffisante, tout en limitant l’épaisseur de la gaine 4. La prévision de deux couches renforcées 16 superposées permet d’améliorer la tenue mécanique de la gaine 4, tout en ayant une gaine 4 dont l’épaisseur est contenue. The thickness of the tube 14, taken between its internal surface 14A and its external surface 14B, is between 280 pm and 600 pm. The provision of a single reinforced layer 16 makes it possible to obtain a sheath 4 having sufficient mechanical strength, while limiting the thickness of the sheath 4. The provision of two superimposed reinforced layers 16 makes it possible to improve the mechanical strength of the sheath 4, while having a sheath 4 whose thickness is contained.

Dans chaque couche renforcée 16, les fibres de renfort sont par exemple disposées selon un agencement à deux ou trois dimensions. In each reinforced layer 16, the reinforcing fibers are for example arranged in a two- or three-dimensional arrangement.

Les fibres de renfort d’une ou de chaque couche renforcée 16 sont par exemple déposées par enroulement filamentaire (enroulement d’un fil sous tension autour d’un mandrin en rotation). The reinforcing fibers of one or each reinforced layer 16 are for example deposited by filament winding (winding a wire under tension around a rotating mandrel).

Ceci permet d’atteindre un bon état de surface et une forte fraction volumique de fibres pour obtenir un tube possédant les caractéristiques mécaniques requises pour une gaine de crayon de combustible nucléaire. This makes it possible to achieve a good surface finish and a high volume fraction of fibers to obtain a tube with the mechanical characteristics required for a nuclear fuel rod cladding.

Dans chaque couche renforcée 16, les fibres de renfort sont par exemple enroulées de manière hélicoïdale autour de l’axe longitudinal A, en faisant de préférence un angle d’enroulement ±0 compris entre 30° et 60° avec la direction de l’axe longitudinal A, en particulier un angle d’enroulement ±0 d’environ 45° avec la direction de l’axe longitudinal A. In each reinforced layer 16, the reinforcing fibers are for example wound helically around the longitudinal axis A, preferably making a winding angle ±0 of between 30° and 60° with the direction of the longitudinal axis A, in particular a winding angle ±0 of approximately 45° with the direction of the longitudinal axis A.

L’enroulement filamentaire est effectué sans entrelacement des fibres de renfort, en particulier sans tressage des fibres de renfort, et/ou avec entrelacement des fibres de renfort, par exemple avec tressage des fibres de renfort. Filament winding is carried out without interlacing the reinforcing fibers, in particular without braiding the reinforcing fibers, and/or with interlacing the reinforcing fibers, for example with braiding the reinforcing fibers.

Avantageusement, les fibres de renfort sont préalablement revêtues d’une interphase fibre/matrice (couche mince intermédiaire avec un rôle de « fusible mécanique ») avant d’être incorporées dans une matrice céramique, par exemple par infiltration chimique en phase vapeur (ou CVI de l’anglais « Chemical Vapor Infiltration »). Ceci permet d’améliorer la tolérance aux dommages du matériau composite du tube 14. Advantageously, the reinforcing fibers are pre-coated with a fiber/matrix interphase (thin intermediate layer with a “mechanical fuse” role) before being incorporated into a ceramic matrix, for example by chemical vapor infiltration (or CVI). This improves the damage tolerance of the composite material of the tube 14.

En option, le tube 14 comprend au moins une couche non renforcée 20. Optionally, the tube 14 comprises at least one unreinforced layer 20.

Chaque couche non-renforcée 20 est de préférence réalisée dans la matrice céramique non renforcée par des fibres de renfort céramique, ou autrement dit dans le même matériau que la matrice céramique de la ou des couches renforcées 16 non renforcé par des fibres de renfort céramique. Each unreinforced layer 20 is preferably made in the ceramic matrix not reinforced by ceramic reinforcing fibers, or in other words in the same material as the ceramic matrix of the reinforced layer(s) 16 not reinforced by ceramic reinforcing fibers.

La réalisation d’une couche non renforcée 20 dans le même matériau que celui de la matrice des couches renforcées 16 permet une bonne cohésion entre les couches du tube 14, et permet de limiter les contraintes d’origine thermique et liées aux différences de comportement sous irradiation. The production of an unreinforced layer 20 in the same material as that of the matrix of the reinforced layers 16 allows good cohesion between the layers of the tube 14, and makes it possible to limit the constraints of thermal origin and linked to the differences in behavior under irradiation.

Le tube 14 comprend par exemple une couche non renforcée 20 interne recouvrant la ou les couches renforcées 16 du côté de la surface interne 14A du tube 14, et définissant de préférence la surface interne 14A du tube 14, et/ou une couche non renforcée 20 externe recouvrant la ou les couches renforcées 16 du côté de la face externe 14B du tube 14, et définissant de préférence la surface externe 14B du tube14. The tube 14 comprises for example an internal unreinforced layer 20 covering the reinforced layer(s) 16 on the side of the internal surface 14A of the tube 14, and preferably defining the internal surface 14A of the tube 14, and/or an external unreinforced layer 20 covering the reinforced layer(s) 16 on the side of the external face 14B of the tube 14, and preferably defining the external surface 14B of the tube 14.

Des couches non renforcées 20 interne et externe permettent de maitriser les dimensions du tube 14, en particulier le diamètre interne du tube 14 et le diamètre externe du tube 14, et les états de surfaces des surfaces interne 14A et externe 14B du tube 14, par exemple par reprise par usinage et/ou par rodage des couches non renforcées 20 pour former les surfaces interne 14A et externe 14B du tube 14. Unreinforced inner and outer layers 20 make it possible to control the dimensions of the tube 14, in particular the inner diameter of the tube 14 and the outer diameter of the tube 14, and the surface conditions of the inner 14A and outer 14B surfaces of the tube 14, for example by machining and/or lapping the unreinforced layers 20 to form the inner 14A and outer 14B surfaces of the tube 14.

Lorsque le tube 14 comprend deux couches renforcées 16, en option, le tube 14 comprend une couche non renforcée 20 intermédiaire intercalée entre les deux couches renforcées 16. When the tube 14 comprises two reinforced layers 16, optionally, the tube 14 comprises an intermediate unreinforced layer 20 interposed between the two reinforced layers 16.

De préférence, le tube 14 est formé exclusivement de la matrice céramique et des fibres de renfort céramique. Le tube 14 comprend au moins une couche renforcée 16 dans laquelle la matrice céramique est renforcée par les fibres de renfort céramique en formant ainsi un matériau composite, et, optionnellement, au moins une couche non renforcée 20 réalisées avec la matrice céramique non renforcée par les fibres de renfort céramique. Preferably, the tube 14 is formed exclusively from the ceramic matrix and the ceramic reinforcing fibers. The tube 14 comprises at least one reinforced layer 16 in which the ceramic matrix is reinforced by the ceramic reinforcing fibers, thereby forming a composite material, and, optionally, at least one unreinforced layer 20 made with the ceramic matrix not reinforced by the ceramic reinforcing fibers.

Un procédé de fabrication du tube 14 comprend par exemple la réalisation de la ou des couches renforcées 16 par enroulement filamentaire des fibres de renfort puis infiltration des fibres de renfort avec la matrice, par exemple par infiltration chimique en phase vapeur, puis dépôt d’une couche non renforcée 20 interne et/ou d’une couche non- renforcée 20 externe, puis, de préférence, la reprise de la surface interne 14A et/ou de la surface externe 14B du tube 14, par exemple par usinage et/ou rodage. A method of manufacturing the tube 14 comprises, for example, producing the reinforced layer(s) 16 by filament winding the reinforcing fibers and then infiltrating the reinforcing fibers with the matrix, for example by chemical vapor infiltration, then depositing an internal non-reinforced layer 20 and/or an external non-reinforced layer 20, then, preferably, reworking the internal surface 14A and/or the external surface 14B of the tube 14, for example by machining and/or lapping.

Pour prévoir une couche non renforcée 20 intermédiaire, le procédé de fabrication comprend par exemple la réalisation d’une couche renforcée 16, puis le dépôt de la couche non renforcée 20 intermédiaire par-dessus ladite couche renforcée 16, puis la réalisation de l’autre couche renforcée 16 par-dessus la couche non renforcée 20 intermédiaire. To provide an intermediate unreinforced layer 20, the manufacturing method comprises, for example, producing a reinforced layer 16, then depositing the intermediate unreinforced layer 20 over said reinforced layer 16, then producing the other reinforced layer 16 over the intermediate unreinforced layer 20.

Dans ce qui suit, les épaisseurs sont prises radialement relativement à l’axe longitudinal A. In the following, the thicknesses are taken radially relative to the longitudinal axis A.

En particulier, le tube 14 présente une épaisseur (E1 sur la Figure 2) prise entre la surface interne 14A et la surface externe 14B du tube 14, en incluant la ou les couches renforcées 16, et la ou les éventuelles couches non renforcées 20. In particular, the tube 14 has a thickness (E1 in Figure 2) taken between the internal surface 14A and the external surface 14B of the tube 14, including the reinforced layer(s) 16, and the possible non-reinforced layer(s) 20.

Dans des exemples de réalisation, le tube 14 comprend une seule couche renforcée 16, l’épaisseur E1 du tube 14 étant comprise entre 280 pm et 340 pm. In exemplary embodiments, the tube 14 comprises a single reinforced layer 16, the thickness E1 of the tube 14 being between 280 μm and 340 μm.

Dans des exemples de réalisation, le tube 14 comprend exactement deux couches renforcées 16, l’épaisseur E1 du tube 14 étant comprise entre 450 pm et 600 pm. In exemplary embodiments, the tube 14 comprises exactly two reinforced layers 16, the thickness E1 of the tube 14 being between 450 μm and 600 μm.

La doublure interne 18 est de préférence en contact avec la surface interne 14A du tube 14. La gaine 4 est dépourvue de jeu radial entre le tube 14 et la doublure interne 18.The inner liner 18 is preferably in contact with the inner surface 14A of the tube 14. The sheath 4 is free of radial play between the tube 14 and the internal lining 18.

La doublure interne 18 est de préférence pleine. La doublure interne 18 est étanche aux fluides, en particulier au gaz. The inner lining 18 is preferably solid. The inner lining 18 is fluid-tight, particularly gas-tight.

La doublure interne 18 est par exemple métallique, i.e. réalisée en métal. The internal lining 18 is for example metallic, i.e. made of metal.

La doublure interne 18 est par exemple réalisée en zirconium pur ou en un alliage à base de zirconium contenant au moins 95% en poids de zirconium. The internal lining 18 is for example made of pure zirconium or of a zirconium-based alloy containing at least 95% by weight of zirconium.

L’expression « zirconium pur » désigne un matériau contenant au moins 99 % en poids de zirconium. Le reste du matériau est constitué d’inévitables impuretés. The term "pure zirconium" refers to a material containing at least 99% zirconium by weight. The remainder of the material consists of unavoidable impurities.

L’alliage à base de zirconium est par exemple choisi parmi un des alliages connus tels que M5, ZIRLO, E110, HANA, N36, Zr-2.5Nb, Zircaloy-2 et Zircaloy 4. The zirconium-based alloy is, for example, chosen from one of the known alloys such as M5, ZIRLO, E110, HANA, N36, Zr-2.5Nb, Zircaloy-2 and Zircaloy 4.

La doublure interne 18 présente une épaisseur (E2 sur la Figure 2) comprise entre 50 pm et 200 pm, en particulier entre 50 pm et 150 pm. The inner lining 18 has a thickness (E2 in Figure 2) of between 50 pm and 200 pm, in particular between 50 pm and 150 pm.

La doublure interne 18 est par exemple pré-oxydée en milieu contrôlé pour optimiser ses caractéristiques d’étanchéité et/ou de perméabilité au gaz comme le tritium. The internal lining 18 is for example pre-oxidized in a controlled environment to optimize its sealing characteristics and/or permeability to gas such as tritium.

La doublure interne 18 pré-oxydée est fabriquée intentionnellement avec une couche d’oxyde. La couche d’oxyde est présente sur le doublure interne 18 avant l’utilisation du crayon de combustible nucléaire, en particulier dans un réacteur nucléaire. The pre-oxidized inner liner 18 is intentionally manufactured with an oxide layer. The oxide layer is present on the inner liner 18 before the nuclear fuel rod is used, particularly in a nuclear reactor.

La gaine 4 et/ou ses bouchons 6 comprennent en option une couche externe de protection 22. La couche de protection 22 recouvre la surface externe 14B du tube 14. The sheath 4 and/or its caps 6 optionally comprise an external protective layer 22. The protective layer 22 covers the external surface 14B of the tube 14.

La couche externe de protection 22 est par exemple métallique. The outer protective layer 22 is, for example, metallic.

La couche externe de protection 22 est réalisée en chrome pur ou en alliage à base de chrome contenant au moins 85% en poids de chrome ou en zirconium pur ou en alliage à base de zirconium contenant au moins 85% en poids de zirconium ou en titane pur ou en alliage à base de titane contenant au moins 80% en poids de titane. The outer protective layer 22 is made of pure chromium or a chromium-based alloy containing at least 85% by weight of chromium or of pure zirconium or a zirconium-based alloy containing at least 85% by weight of zirconium or of pure titanium or a titanium-based alloy containing at least 80% by weight of titanium.

L’expression « chrome pur » désigne un matériau comprenant au moins 99% en poids de chrome. Le reste du matériau est constitué d’inévitables impuretés. The term "pure chromium" refers to a material that contains at least 99% chromium by weight. The remainder of the material consists of unavoidable impurities.

L’expression « titane pur » désigne un matériau comprenant au moins 99% en poids de titane. Le reste du matériau est constitué d’inévitables impuretés. The term "pure titanium" refers to a material that is at least 99% titanium by weight. The remainder of the material consists of unavoidable impurities.

De préférence, la couche externe de protection 22 présente une épaisseur (E3 sur la Figure 2) comprise entre 5 pm et 40 pm. Preferably, the outer protective layer 22 has a thickness (E3 in Figure 2) of between 5 μm and 40 μm.

Comme visible sur la Figure 1 , la gaine 4 comprend de préférence deux éléments d’obturation 24 fermant chacun une extrémité axiale respective de la doublure interne 18, de préférence de manière étanche aux fluides, en particulier au gaz. As visible in Figure 1, the sheath 4 preferably comprises two sealing elements 24 each closing a respective axial end of the internal lining 18, preferably in a fluid-tight manner, in particular gas-tight.

Chaque élément d’obturation 24 est par exemple fixé à la doublure interne 18 en étant soudé et/ou brasé et/ou collé et/ou inséré en force à l’extrémité axiale correspondante de la doublure interne 18. De préférence, lors de la fermeture de la doublure interne 18, la nature et la pression du gaz contenu dans la doublure interne 18 sont contrôlées, par exemple en utilisant un queusot. Le gaz est par exemple de l’hélium. La pression est avantageusement égale ou inférieure à 200 bars, de préférence égale ou inférieure à 100 bars, encore de préférence égale ou inférieure à 20 bars. La pression est par exemple de 15 bars. Each sealing element 24 is for example fixed to the internal lining 18 by being welded and/or brazed and/or glued and/or inserted by force at the corresponding axial end of the internal lining 18. Preferably, when closing the inner lining 18, the nature and pressure of the gas contained in the inner lining 18 are controlled, for example using a valve. The gas is for example helium. The pressure is advantageously equal to or less than 200 bars, preferably equal to or less than 100 bars, more preferably equal to or less than 20 bars. The pressure is for example 15 bars.

Dans des exemples de réalisation, chaque élément d’obturation 24 est métallique. En particulier, chaque élément d’obturation 24 est réalisé dans le même matériau que la doublure interne 18, et est de préférence soudé à celle-ci, et aussi, optionnellement, soudé, brasé, collé et/ou inséré en force. In exemplary embodiments, each sealing element 24 is metallic. In particular, each sealing element 24 is made of the same material as the inner liner 18, and is preferably welded thereto, and also, optionally, welded, brazed, glued and/or force-fitted.

Les éléments d’obturation 24 fermant la doublure interne 18 sont par exemple distincts des bouchons 6 fermant les extrémités axiales du tube 14. The sealing elements 24 closing the internal lining 18 are for example distinct from the plugs 6 closing the axial ends of the tube 14.

Dans des exemples de réalisation, chaque bouchon 6 est réalisé en matériau composite comprenant une matrice renforcée de fibres de renfort, en particulier une matrice céramique renforcée de fibres de renfort, encore plus en particulier une matrice en carbure de silicium renforcée de fibres en carbures de silicium. In exemplary embodiments, each plug 6 is made of a composite material comprising a matrix reinforced with reinforcing fibers, in particular a ceramic matrix reinforced with reinforcing fibers, even more in particular a silicon carbide matrix reinforced with silicon carbide fibers.

Chaque bouchon 6 est par exemple fixé au tube 14 en étant brasé et/ou collé et/ou inséré en force et/ou goupillé à l’extrémité axiale correspondante du tube 14. Dans des exemples de réalisation avantageux, chaque bouchon 6 est brasé ou goupillé et brasé. Each plug 6 is for example fixed to the tube 14 by being brazed and/or glued and/or inserted by force and/or pinned at the corresponding axial end of the tube 14. In advantageous embodiments, each plug 6 is brazed or pinned and brazed.

Lorsqu’une couche externe de protection 22 est prévue, celle-ci recouvre le tube 14 sur toute sa longueur, et, de préférence, recouvre partiellement ou complètement chaque bouchon 6, notamment à la jonction entre le bouchon 6 et le tube 14. When an external protective layer 22 is provided, this covers the tube 14 over its entire length, and preferably partially or completely covers each plug 6, in particular at the junction between the plug 6 and the tube 14.

Selon un procédé de fabrication du crayon de combustible nucléaire 2, le tube 14 et la doublure interne 18 sont par exemple fabriqués séparément, puis la doublure interne 18 est fermée, son étanchéité au gaz étant de préférence contrôlée, puis la doublure interne 18 préalablement fermée est insérée dans le tube 14. According to a method of manufacturing the nuclear fuel rod 2, the tube 14 and the internal lining 18 are for example manufactured separately, then the internal lining 18 is closed, its gas tightness preferably being checked, then the previously closed internal lining 18 is inserted into the tube 14.

En particulier, le procédé de fabrication comprend, la fabrication du tube 14, l’obtention de la doublure interne 18, le remplissage de la doublure interne 18 avec le combustible nucléaire, par exemple par insertion des pastilles 8 dans la doublure interne 18, la fermeture de la doublure interne 18 à ses extrémités axiales à l’aide des éléments d’obturation 24, de préférence, le contrôle de l’étanchéité au gaz de la doublure interne 18 fermée, l’insertion de la doublure interne 18 remplie et fermée dans le tube 14, puis la fermeture du tube 14 à ses extrémités axiales par les bouchons 6. In particular, the manufacturing method comprises manufacturing the tube 14, obtaining the inner lining 18, filling the inner lining 18 with nuclear fuel, for example by inserting the pellets 8 into the inner lining 18, closing the inner lining 18 at its axial ends using the sealing elements 24, preferably checking the gas tightness of the closed inner lining 18, inserting the filled and closed inner lining 18 into the tube 14, then closing the tube 14 at its axial ends by the plugs 6.

La fabrication du tube 14 comprend la réalisation de la ou des couches renforcées 16, en particulier par enroulement filamentaire de fibres de renfort, par exemple sur une forme cylindrique (ou mandrin). L’enroulement filamentaire est réalisé sans entrelacement des fibres de renforts et/ou avec entrelacement des fibres de renforts, par exemple par tressage. The manufacture of the tube 14 comprises the production of the reinforced layer(s) 16, in particular by filament winding of reinforcing fibers, for example on a cylindrical shape (or mandrel). The filament winding is carried out without interlacing of reinforcing fibers and/or with interlacing of reinforcing fibers, for example by braiding.

Les fibres de renfort sont par exemple imprégnées avant le dépôt par enroulement filamentaire, par exemple par passage dans un bain d’imprégnation, et/ou après leur enroulement filamentaire, par exemple par infiltration, en particulier par infiltration chimique en phase vapeur. The reinforcing fibers are, for example, impregnated before deposition by filament winding, for example by passing through an impregnation bath, and/or after their filament winding, for example by infiltration, in particular by chemical vapor infiltration.

Le procédé de fabrication du tube 14 comprend la réalisation d’une seule couche renforcée 16 ou d’exactement deux couches renforcées 16. The method of manufacturing the tube 14 comprises the production of a single reinforced layer 16 or exactly two reinforced layers 16.

Optionnellement, le procédé de fabrication du tube 14 comprend le dépôt d’une couche non renforcée 20 intermédiaire entre les deux couches renforcées 16. Dans ce cas, le procédé de fabrication comprend par exemple la réalisation d’une couche renforcée 16, puis le dépôt d’une couche non renforcée 20 sur le couche renforcée 16, puis la réalisation d’une autre couche renforcée par-dessus la couche non renforcée 20 qui se retrouve intercalée entre les deux couches renforcées 16. Optionally, the method of manufacturing the tube 14 comprises the deposition of an intermediate non-reinforced layer 20 between the two reinforced layers 16. In this case, the manufacturing method comprises, for example, the production of a reinforced layer 16, then the deposition of an non-reinforced layer 20 on the reinforced layer 16, then the production of another reinforced layer over the non-reinforced layer 20 which is interposed between the two reinforced layers 16.

Optionnellement, la réalisation de la ou des couches renforcées 16 est suivie d’un dépôt d’une couche non renforcée 20 interne et/ou d’une couche non renforcée 20 externe Optionnellement, le procédé de fabrication comprend le dépôt d’une couche externe de protection 22 sur la surface externe 14B du tube, par exemple par projection plasma sous très basse pression (ou VLPPS de l’anglais « Vacuum Low Pressure Plasma Spraying ») ou par dépôt physique en phase vapeur (ou PVD de l’anglais « Physical Vapor Deposition »). Optionally, the production of the reinforced layer(s) 16 is followed by deposition of an internal non-reinforced layer 20 and/or an external non-reinforced layer 20. Optionally, the manufacturing method comprises the deposition of an external protective layer 22 on the external surface 14B of the tube, for example by very low pressure plasma spraying (or VLPPS for “Vacuum Low Pressure Plasma Spraying”) or by physical vapor deposition (or PVD for “Physical Vapor Deposition”).

Le dépôt de la couche externe de protection 22 est par exemple réalisé lorsque la doublure interne 18 contenant le combustible est présente à l’intérieur du tube 14, et de préférence après la fermeture du tube 14 à l’aide des bouchons 6. The deposition of the external protective layer 22 is for example carried out when the internal lining 18 containing the fuel is present inside the tube 14, and preferably after the tube 14 has been closed using the plugs 6.

Dans des modes de mise en œuvre, comme décrit ci-dessus, le tube 14 est formé sur une forme cylindrique avant d’insérer la doublure interne 18 remplie et fermée à l’intérieur du tube 14. In embodiments as described above, the tube 14 is formed into a cylindrical shape prior to inserting the filled and sealed inner liner 18 inside the tube 14.

Dans d’autres modes de mise en œuvre, la doublure interne 18 est remplie avec le combustible nucléaire et fermée à ses extrémités axiales par les éléments d’obturation 24, puis le tube 14 est formé autour de la doublure interne 18. La doublure interne 18 sert de forme pour la réalisation du tube 14. In other embodiments, the inner liner 18 is filled with nuclear fuel and closed at its axial ends by the sealing elements 24, then the tube 14 is formed around the inner liner 18. The inner liner 18 serves as a form for the production of the tube 14.

La gaine 4 proposée présente un comportement amélioré en conditions normales d’utilisation et en conditions accidentelles. The proposed sheath 4 exhibits improved behavior under normal conditions of use and in accident conditions.

Le tube 14 en matériau composite à matrice céramique renforcée de fibres de carbure de silicium permet d’obtenir une gaine 6 qui est très résistante, notamment en conditions accidentelles. Le risque de rupture de relâchement de combustible nucléaire hors de la gaine est donc diminué. Une matrice en carbure de silicium renforcée de fibres de renfort en carbure de silicium est particulièrement résistante. The tube 14 made of ceramic matrix composite material reinforced with silicon carbide fibers makes it possible to obtain a cladding 6 which is very resistant, particularly in accident conditions. The risk of rupture from the release of nuclear fuel out of the sheath is therefore reduced. A silicon carbide matrix reinforced with silicon carbide reinforcing fibers is particularly resistant.

La doublure interne 18 prévue dans le tube 14 permet d’améliorer l’étanchéité et en particulier d’empêcher le relâchement de gaz de fission hors de la gaine 6. The internal lining 18 provided in the tube 14 makes it possible to improve the sealing and in particular to prevent the release of fission gases outside the sheath 6.

L’ajout d’un revêtement de protection (i.e. la couche externe de protection 22) recouvrant la surface externe du tube 14 de la gaine 4, et de préférence aussi sur les bouchons 6, permet de limiter le risque de corrosion hydrothermal par le fluide circulant dans le réacteur nucléaire autour du crayon de combustible nucléaire 2. Il permet en particulier d’éviter ou au moins limiter l’érosion du matériau composite du tube 14 et/ou de limiter les relâchements de silicium dans le fluide primaire (lorsque le tube 14 comporte du silicium) et/ou d’éviter ou au moins limiter les dépôts, en particulier les dépôts de CRUD (de l’anglais « Chalk River Unidentified Deposits »). The addition of a protective coating (i.e. the external protective layer 22) covering the external surface of the tube 14 of the cladding 4, and preferably also on the plugs 6, makes it possible to limit the risk of hydrothermal corrosion by the fluid circulating in the nuclear reactor around the nuclear fuel rod 2. In particular, it makes it possible to avoid or at least limit the erosion of the composite material of the tube 14 and/or to limit the release of silicon into the primary fluid (when the tube 14 contains silicon) and/or to avoid or at least limit deposits, in particular CRUD deposits (from the English “Chalk River Unidentified Deposits”).

L’épaisseur E1 du tube 14 comprise entre 280 pm et 340 pm si le tube 14 comprend une seule couche renforcée 16 ou entre 450 pm et 600 pm si le tube 14 comprend exactement deux couches renforcées 16, permet de former une gaine 4 présentant des dimensions (en particulier diamètre interne et diamètre externe) compatibles avec les pastilles de combustible nucléaire existantes. The thickness E1 of the tube 14, between 280 pm and 340 pm if the tube 14 comprises a single reinforced layer 16 or between 450 pm and 600 pm if the tube 14 comprises exactly two reinforced layers 16, makes it possible to form a cladding 4 having dimensions (in particular internal diameter and external diameter) compatible with existing nuclear fuel pellets.

L’épaisseur E1 du tube 14 comprise entre 280 pm et 340 pm si le tube 14 comprend une seule couche renforcée 16 ou entre 450 pm et 600 pm si le tube 14 comprend exactement deux couches renforcées 16 permet, avec le tube 14 réalisé au moins en partie en matériau composite, en particulier du type SiC/SiCf ou SiC/Cf, un compromis satisfaisant entre le transfert thermique et la tenue mécanique en fonctionnement normal et en fonctionnement accidentel, avec une bonne tolérance aux dommages pouvant être subis par la gaine 4. The thickness E1 of the tube 14 of between 280 pm and 340 pm if the tube 14 comprises a single reinforced layer 16 or between 450 pm and 600 pm if the tube 14 comprises exactly two reinforced layers 16 allows, with the tube 14 made at least partly of composite material, in particular of the SiC/SiCf or SiC/Cf type, a satisfactory compromise between heat transfer and mechanical strength in normal operation and in accidental operation, with good tolerance to damage that may be suffered by the sheath 4.

La limite inférieure de l’épaisseur E1 du tube 14 permet de supporter des niveaux de contrainte et de déformation observés au cours de l’utilisation de la gaine 4 dans un réacteur nucléaire, en condition de fonctionnement normal ou incidental . The lower limit of the thickness E1 of the tube 14 makes it possible to withstand stress and deformation levels observed during the use of the cladding 4 in a nuclear reactor, in normal or incident operating conditions.

De préférence, la limite inférieure de l’épaisseur E1 est configurée pour la tenue du tube 14 sous une sollicitation mécanique en traction avec un allongement supérieur à 0,3% de déformation et/ou un niveau de contrainte avant rupture supérieur à 100 MPa. Preferably, the lower limit of the thickness E1 is configured to hold the tube 14 under mechanical tensile stress with an elongation greater than 0.3% of deformation and/or a stress level before rupture greater than 100 MPa.

La limite supérieure de l’épaisseur E1 du tube 14 permet d’assurer un transfert thermique satisfaisant en cours d’utilisation, entre le combustible nucléaire contenu dans le tube 14 et le fluide caloporteur circulant à l’extérieur du tube 14 dans un réacteur nucléaire dans lequel un assemblage de combustible nucléaire intégrant le crayon de combustible 2 est inséré. En effet, en cours d’utilisation, un gradient thermique s’établit dans l’épaisseur du tube 14 du fait des échanges thermiques entre le combustible nucléaire contenu dans la gaine 4 et le fluide caloporteur circulant à l’extérieur de la gaine 4. The upper limit of the thickness E1 of the tube 14 makes it possible to ensure satisfactory heat transfer during use, between the nuclear fuel contained in the tube 14 and the heat transfer fluid circulating outside the tube 14 in a nuclear reactor in which a nuclear fuel assembly integrating the fuel rod 2 is inserted. Indeed, during use, a thermal gradient is established in the thickness of the tube 14 due to the thermal exchanges between the nuclear fuel contained in the cladding 4 and the heat transfer fluid circulating outside the cladding 4.

Ce gradient thermique conduit à des contraintes internes directes, par dilatation thermique, et des contraintes internes indirectes, par établissement d’un gradient de gonflement sous irradiation, dans l’épaisseur du tube 14. This thermal gradient leads to direct internal stresses, by thermal expansion, and indirect internal stresses, by establishing a swelling gradient under irradiation, in the thickness of the tube 14.

Des calculs de la contrainte circonférentielle en traction (ou contrainte azimutale) à la surface interne 14A du tube 14 en fonction de l’épaisseur tube 14 pour des conditions de fonctionnement normal ou incidental, montrent que cette contrainte circonférentielle en traction maximale augmente en fonction de l’épaisseur E1 du tube 14. Calculations of the circumferential tensile stress (or azimuthal stress) at the internal surface 14A of the tube 14 as a function of the thickness of the tube 14 for normal or incidental operating conditions, show that this maximum circumferential tensile stress increases as a function of the thickness E1 of the tube 14.

Ces calculs peuvent être réalisés en prenant en compte la différence de pression entre l’intérieur et l’extérieur de la gaine 4, la dilatation thermique de la gaine 4 et le gonflement de la gaine 4. These calculations can be performed by taking into account the pressure difference between the inside and outside of the sheath 4, the thermal expansion of the sheath 4 and the swelling of the sheath 4.

La Figure 3 est un graphique illustrant l’évolution de la contrainte circonférentielle en traction maximale à la surface interne 14A du tube 14 en fonction de l’épaisseur E1 du tube 14 (courbe C1), pour des conditions de fonctionnement normal ou incidental dans un réacteur nucléaire. Figure 3 is a graph illustrating the evolution of the maximum tensile circumferential stress at the internal surface 14A of the tube 14 as a function of the thickness E1 of the tube 14 (curve C1), for normal or incident operating conditions in a nuclear reactor.

Des calculs similaires aux précédents montrent que lors d’un arrêt à froid en intercycles, la pressurisation interne du crayon 2 conduit à une mise en traction du matériau composite à matrice céramique renforcé de fibres céramiques, la contrainte circonférentielle en traction maximale augmentant lorsque l’épaisseur du tube 14 diminue. Calculations similar to the previous ones show that during a cold stop between cycles, the internal pressurization of the rod 2 leads to a tensile stress on the ceramic matrix composite material reinforced with ceramic fibers, the maximum tensile circumferential stress increasing when the thickness of the tube 14 decreases.

La Figure 4 est un graphique illustrant l’évolution de la contrainte circonférentielle en traction maximale à la surface interne 14A du tube 14 en fonction de l’épaisseur E1 du tube 14 (courbe C2) au cours d’un arrêt à froid inter-cycles dans un réacteur nucléaire. Figure 4 is a graph illustrating the evolution of the maximum tensile circumferential stress at the internal surface 14A of the tube 14 as a function of the thickness E1 of the tube 14 (curve C2) during an inter-cycle cold shutdown in a nuclear reactor.

Ainsi, la limite supérieure de l’épaisseur E1 du tube 14 permet de limiter les contraintes circonférentielles en traction à la surface interne 14A du tube 14 en conditions de fonctionnement normal et incidentel dans un réacteur, et la limite inférieure de l’épaisseur E1 du tube 14 permet de limiter les contraintes circonférentielles en traction pendant des phases d’arrêt à froid du réacteur nucléaire, par exemple en inter-cycles. Thus, the upper limit of the thickness E1 of the tube 14 makes it possible to limit the circumferential tensile stresses at the internal surface 14A of the tube 14 under normal and incident operating conditions in a reactor, and the lower limit of the thickness E1 of the tube 14 makes it possible to limit the circumferential tensile stresses during cold shutdown phases of the nuclear reactor, for example between cycles.

Les limites minimale et maximale de l’épaisseur E1 du tube 14 sont choisies pour que les contraintes circonférentielles en traction restent inférieures à une limite élastique cible en traction du matériau composite à matrice céramique renforcé de fibres céramiques (en particulier SiC/SiCf ou SiC/Cf). The minimum and maximum limits of the thickness E1 of the tube 14 are chosen so that the circumferential tensile stresses remain lower than a target elastic tensile limit of the ceramic matrix composite material reinforced with ceramic fibers (in particular SiC/SiCf or SiC/Cf).

La limite élastique cible en traction est de préférence égale ou supérieure à 80 MPa.The target tensile yield strength is preferably equal to or greater than 80 MPa.

La prévision d’une couche non renforcée 20 en face externe, présentant de préférence un état de surface micrométrique, permet d’assurer une protection de la ou des couches renforcées 16 vis-à-vis de l’extérieur, en particulier vis-à-vis de l’érosion/corrosion au contact du fluide caloporteur circulant dans un réacteur nucléaire dans lequel est inséré un assemblage de combustible nucléaire intégrant le crayon de combustible 2. The provision of an unreinforced layer 20 on the external face, preferably having a micrometric surface condition, makes it possible to ensure protection of the reinforced layers 16 with respect to the exterior, in particular with respect to erosion/corrosion in contact with the heat transfer fluid circulating in a nuclear reactor in which a nuclear fuel assembly integrating the fuel rod 2 is inserted.

De préférence, l’épaisseur totale de la ou des couches renforcées 16 est supérieure à 280pm. Preferably, the total thickness of the reinforced layer(s) 16 is greater than 280 μm.

L’épaisseur totale de la ou des couches renforcées 16 est la somme des épaisseurs des couches renforcées 16 du tube 14. The total thickness of the reinforced layer(s) 16 is the sum of the thicknesses of the reinforced layers 16 of the tube 14.

De préférence, l’épaisseur de la couche non renforcée 20 en face externe est égale ou supérieure à 20 pm, en particulier égale ou supérieure à 30 pm. Ceci permet s’assurer la fonction de protection de la ou les couches renforcées 16 du fluide caloporteur. Preferably, the thickness of the unreinforced layer 20 on the external face is equal to or greater than 20 μm, in particular equal to or greater than 30 μm. This ensures the protection function of the reinforced layer(s) 16 of the heat transfer fluid.

Le tube 14 fermé à ses extrémités axiales par les bouchons 6 et, de préférence muni de la couche externe de protection 22, protège la doublure interne 18 du milieu externe en conditions de fonctionnement normal et en conditions accidentelles. The tube 14 closed at its axial ends by the plugs 6 and, preferably provided with the external protective layer 22, protects the internal lining 18 from the external environment under normal operating conditions and under accident conditions.

La gamme d’épaisseur prévue pour la doublure interne 18 permet une tenue mécanique suffisante avant insertion dans le tube 14, une absorption de neutrons limitée et un transfert thermique satisfaisant. The thickness range provided for the internal lining 18 allows sufficient mechanical strength before insertion into the tube 14, limited neutron absorption and satisfactory heat transfer.

La doublure interne 18 permet d’assurer une étanchéité aux gaz avec un impact limité sur le diamètre interne de la gaine 4. The internal lining 18 ensures gas tightness with limited impact on the internal diameter of the sheath 4.

Le matériau de la doublure 18 doit avoir une faible interaction avec le matériau du tube 14 et avec le combustible nucléaire pour les conditions de température de conditions accidentelles sévères. The liner material 18 must have low interaction with the tube material 14 and with the nuclear fuel for the temperature conditions of severe accident conditions.

La gamme d’épaisseur prévue pour la couche externe de protection 22 permet une absorption de neutrons limitée et un transfert thermique satisfaisant, et assure une bonne durée de vie, avec un risque de délamination maitrisé. Elle permet de réaliser une couche externe de protection 22 qui reste protectrice malgré un gonflement du tube 14 sous irradiation, qui est généralement inférieure à 2%. The thickness range provided for the outer protective layer 22 allows limited neutron absorption and satisfactory heat transfer, and ensures a good service life, with a controlled risk of delamination. It makes it possible to produce an outer protective layer 22 which remains protective despite swelling of the tube 14 under irradiation, which is generally less than 2%.

De préférence, l’épaisseur totale de la gaine 4, comprenant le tube 14, la doublure interne 18, et optionnellement la couche externe de protection 22, est égale ou inférieure à 600 pm, en particulier égale ou inférieure 570 pm. Preferably, the total thickness of the sheath 4, comprising the tube 14, the internal lining 18, and optionally the external protective layer 22, is equal to or less than 600 μm, in particular equal to or less than 570 μm.

L’épaisseur totale de la gaine 4, comprenant le tube 14, la doublure interne 18, et optionnellement la couche externe de protection 22 correspond à la somme des épaisseurs E1 (tube 14), E2 (doublure interne 18) et E3 (couche externe de protection 22) sur la Figure 2. The total thickness of the sheath 4, comprising the tube 14, the internal lining 18, and optionally the external protective layer 22 corresponds to the sum of the thicknesses E1 (tube 14), E2 (internal lining 18) and E3 (external protective layer 22) in Figure 2.

Un crayon de combustible nucléaire peut être prévu pour être utilisé dans un assemblage de combustible nucléaire comprenant un faisceau de crayons de combustible nucléaire parallèles agencés selon une configuration matricielle NxN, N étant un nombre entier, en particulier une configuration matricielle 17x17 ou 14x14. A nuclear fuel rod may be provided for use in a nuclear fuel assembly comprising a bundle of fuel rods parallel nuclear arrays arranged in an NxN matrix configuration, N being an integer, in particular a 17x17 or 14x14 matrix configuration.

L’épaisseur totale de la gaine 4 est par exemple limitée en fonction du nombre N de la configuration matricielle NxN. The total thickness of the sheath 4 is for example limited according to the number N of the NxN matrix configuration.

Dans des exemples, la gaine 4 est configurée pour un crayon de combustible nucléaire 2 pour assemblage de combustible nucléaire comprenant un faisceau de crayons de combustible nucléaire parallèles agencés selon une configuration matricielle 17x17, et l’épaisseur totale de la gaine 4 est égale ou inférieure à 570 pm. In examples, the cladding 4 is configured for a nuclear fuel rod 2 for a nuclear fuel assembly comprising a bundle of parallel nuclear fuel rods arranged in a 17x17 matrix configuration, and the total thickness of the cladding 4 is equal to or less than 570 μm.

Dans des exemples, la gaine 4 est configurée pour un crayon de combustible nucléaire 2 pour assemblage de combustible nucléaire comprenant un faisceau de crayons de combustible nucléaire parallèles agencés selon une configuration matricielle 14x14, et l’épaisseur totale de la gaine 4 est égale ou inférieure à 600 pm. In examples, the cladding 4 is configured for a nuclear fuel rod 2 for a nuclear fuel assembly comprising a bundle of parallel nuclear fuel rods arranged in a 14x14 matrix configuration, and the total thickness of the cladding 4 is equal to or less than 600 μm.

La limitation de l’épaisseur totale de la gaine 4 permet d’assurer la compatibilité de la gaine 4 avec les pastilles de combustible 8 et les assemblages de combustible nucléaire existants. Limiting the total thickness of the cladding 4 ensures the compatibility of the cladding 4 with the fuel pellets 8 and existing nuclear fuel assemblies.

L’invention concerne aussi un assemblage de combustible nucléaire comprenant un faisceau de crayons de combustible nucléaire parallèles agencés selon une configuration matricielle NxN, N étant un nombre entier, en particulier une configuration matricielle 17x17 ou 14x14, chaque crayon possédant une gaine, les gaines des crayons de combustible nucléaire étant telles que défini ci-dessus. The invention also relates to a nuclear fuel assembly comprising a bundle of parallel nuclear fuel rods arranged in an NxN matrix configuration, N being an integer, in particular a 17x17 or 14x14 matrix configuration, each rod having a cladding, the claddings of the nuclear fuel rods being as defined above.

Claims

REVENDICATIONS 1. Gaine de crayon de combustible nucléaire, comprenant un tube (14) s’étendant suivant un axe longitudinal et une doublure interne (18) tubulaire reçue à l’intérieur du tube (14), le tube (14) comprenant au moins une couche renforcée (16) réalisée dans un matériau composite comprenant une matrice céramique renforcée avec des fibres de renfort céramiques, l’épaisseur du tube (14) étant comprise entre 280 pm et 600 pm. 1. Nuclear fuel rod sheath, comprising a tube (14) extending along a longitudinal axis and a tubular internal lining (18) received inside the tube (14), the tube (14) comprising at least one reinforced layer (16) made of a composite material comprising a ceramic matrix reinforced with ceramic reinforcing fibers, the thickness of the tube (14) being between 280 μm and 600 μm. 2. Gaine selon la revendication 1 , dans laquelle le tube (14) comprend une seule couche renforcée (16), l’épaisseur du tube (14) étant comprise entre 280 pm et 340 pm. 2. Sheath according to claim 1, in which the tube (14) comprises a single reinforced layer (16), the thickness of the tube (14) being between 280 μm and 340 μm. 3. Gaine selon la revendication 1 , dans laquelle le tube (14) comprend exactement deux couches renforcées, l’épaisseur du tube (14) étant comprise entre 450 pm et 600 pm. 3. Sheath according to claim 1, in which the tube (14) comprises exactly two reinforced layers, the thickness of the tube (14) being between 450 μm and 600 μm. 4. Gaine selon l’une quelconque des revendications précédentes, dans lequel la matrice céramique est réalisée en carbure de silicium et/ou les fibres de renfort céramiques sont réalisées en carbure de silicium et/ou en carbone. 4. Sheath according to any one of the preceding claims, in which the ceramic matrix is made of silicon carbide and/or the ceramic reinforcing fibers are made of silicon carbide and/or carbon. 5. Gaine selon l’une quelconque des revendications précédentes, dans laquelle une ou chaque couche renforcée (16) est formée avec enroulement filamentaire des fibres de renfort céramiques. 5. A sheath according to any preceding claim, wherein one or each reinforced layer (16) is formed with filament winding of the ceramic reinforcing fibers. 6. Gaine selon l’une quelconque des revendications précédentes, dans laquelle une ou chaque couche renforcée (16) est formée avec enroulement filamentaire des fibres de renfort céramiques sans entrelacement des fibres de renfort céramiques. 6. A sheath according to any preceding claim, wherein one or each reinforced layer (16) is formed with filament winding of the ceramic reinforcing fibers without interlacing of the ceramic reinforcing fibers. 7. Gaine selon l’une quelconque des revendications précédentes, dans laquelle une ou chaque couche renforcée (16) est formée avec enroulement filamentaire des fibres de renfort céramiques avec entrelacement des fibres de renfort céramiques, par exemple par tressage des fibres de renfort céramiques. 7. A sheath according to any preceding claim, wherein one or each reinforced layer (16) is formed with filament winding of the ceramic reinforcing fibers with interlacing of the ceramic reinforcing fibers, for example by braiding the ceramic reinforcing fibers. 8. Gaine selon l’une quelconque des revendications précédentes, dans laquelle l’épaisseur totale de la ou des couches renforcées (16) est égale ou supérieure à 280 pm. 8. Sheath according to any one of the preceding claims, in which the total thickness of the reinforced layer(s) (16) is equal to or greater than 280 μm. 9. Gaine selon l’une quelconque des revendications précédentes, dans laquelle le tube (14) comprend au moins une couche non renforcée (20), réalisée de préférence dans le même matériau que la matrice céramique. 9. Sheath according to any one of the preceding claims, in which the tube (14) comprises at least one unreinforced layer (20), preferably made of the same material as the ceramic matrix. 10. Gaine selon la revendication 9, comprenant une couche non renforcée (20) interne recouvrant la ou les couches renforcées (16) du côté de la face interne du tube (14) et/ou une couche non renforcée (20) externe recouvrant le ou les couches renforcées (16) du côté de la face externe du tube (14) et/ou une couche non renforcée (20) intermédiaire intercalée entre deux couches renforcées (16) du tube (14). 10. Sheath according to claim 9, comprising an internal non-reinforced layer (20) covering the reinforced layer(s) (16) on the side of the internal face of the tube (14) and/or an external non-reinforced layer (20) covering the reinforced layer(s) (16) on the side of the external face of the tube (14) and/or an intermediate non-reinforced layer (20) interposed between two reinforced layers (16) of the tube (14). 11. Gaine selon la revendication 9 ou 10, dans laquelle l’épaisseur de la couche non renforcées (20) externe est égale ou supérieure à 20 pm, en particulier égale ou supérieure à 30 pm. 11. Sheath according to claim 9 or 10, in which the thickness of the external unreinforced layer (20) is equal to or greater than 20 μm, in particular equal to or greater than 30 μm. 12. Gaine selon l’une quelconque des revendications précédentes, dans laquelle le tube (14) est formé exclusivement de la matrice céramique et des fibres de renfort céramique. 12. Sheath according to any one of the preceding claims, in which the tube (14) is formed exclusively from the ceramic matrix and the ceramic reinforcing fibers. 13. Gaine selon l’une quelconque des revendications précédentes, dans laquelle la doublure interne présente une épaisseur comprise entre 50 pm et 200 pm, en particulier entre 50 pm et 150 pm. 13. Sheath according to any one of the preceding claims, in which the internal lining has a thickness of between 50 μm and 200 μm, in particular between 50 μm and 150 μm. 14. Gaine selon l’une quelconque des revendications précédentes, dans laquelle la doublure interne (18) est métallique. 14. Sheath according to any one of the preceding claims, in which the internal lining (18) is metallic. 15. Gaine selon l’une quelconque des revendications précédentes, dans laquelle la doublure interne (18) est réalisée en zirconium pur ou en un alliage à base de zirconium contenant au moins 95% en poids de zirconium. 15. A sheath according to any preceding claim, wherein the inner lining (18) is made of pure zirconium or a zirconium-based alloy containing at least 95% by weight of zirconium. 16. Gaine selon l’une quelconque des revendications précédentes, dans laquelle la doublure interne (18) est pré-oxydée. 16. A sheath according to any preceding claim, wherein the inner lining (18) is pre-oxidized. 17. Gaine selon l’une quelconque des revendications précédentes, comprenant une couche externe de protection (22) recouvrant une surface externe du tube (14). 17. A sheath according to any preceding claim, comprising an outer protective layer (22) covering an outer surface of the tube (14). 18. Gaine selon la revendication 17, dans laquelle la couche externe de protection (22) est métallique. 18. Sheath according to claim 17, in which the outer protective layer (22) is metallic. 19. Gaine selon la revendication 17 ou 18, dans laquelle la couche externe de protection (22) est réalisée en chrome pur ou en alliage à base de chrome contenant au moins 85% en poids de chrome ou en zirconium pur ou en alliage à base de zirconium contenant au moins 85% en poids de zirconium ou en titane pur ou en alliage à base de titane contenant au moins 80% en poids de titane. 19. Sheath according to claim 17 or 18, in which the outer protective layer (22) is made of pure chromium or a chromium-based alloy containing at least 85% by weight of chromium or of pure zirconium or a zirconium-based alloy containing at least 85% by weight of zirconium or of pure titanium or a titanium-based alloy containing at least 80% by weight of titanium. 20. Gaine selon l’une quelconque des revendications 17 à 19, dans laquelle la couche externe de protection (22) présente une épaisseur comprise entre 5 pm et 40 pm. 20. Sheath according to any one of claims 17 to 19, in which the external protective layer (22) has a thickness of between 5 μm and 40 μm. 21. Gaine selon l’une quelconque des revendications précédentes, dans laquelle l’épaisseur totale de la gaine (4) est égale ou inférieure à 600 pm, la gaine (4) étant de préférence configurée pour un crayon de combustible nucléaire (2) pour assemblage de combustible nucléaire comprenant un faisceau de crayons de combustible nucléaire parallèles agencés selon une configuration matricielle 14x14, ou dans laquelle l’épaisseur totale de la gaine (4) est égale ou inférieure à 570 pm, la gaine (4) étant de préférence configurée pour un crayon de combustible nucléaire (2) pour assemblage de combustible nucléaire comprenant un faisceau de crayons de combustible nucléaire agencés selon une configuration matricielle 17x17. 21. Cladding according to any one of the preceding claims, wherein the total thickness of the cladding (4) is equal to or less than 600 pm, the cladding (4) preferably being configured for a nuclear fuel rod (2) for a nuclear fuel assembly comprising a bundle of parallel nuclear fuel rods arranged in a 14x14 matrix configuration, or wherein the total thickness of the cladding (4) is equal to or less than 570 pm, the cladding (4) preferably being configured for a nuclear fuel rod (2) for a nuclear fuel assembly comprising a bundle of nuclear fuel rods arranged in a 17x17 matrix configuration. 22. Crayon de combustible nucléaire comprenant une gaine selon l’une quelconque des revendications précédentes, du combustible nucléaire reçu à l’intérieur de la doublure interne (18) de la gaine, et deux bouchons (6), chaque bouchon (6) fermant une extrémité axiale respective de la gaine. 22. A nuclear fuel rod comprising a cladding according to any one of the preceding claims, nuclear fuel received inside the inner lining (18) of the cladding, and two plugs (6), each plug (6) closing a respective axial end of the cladding. 23. Crayon de combustible nucléaire selon la revendication 22, dans lequel chaque bouchon (6) est réalisé en matériau composite comprenant une matrice céramique renforcée de fibres de renfort céramiques, en particulier une matrice en carbure de silicium renforcée de fibres de renfort en carbures de silicium et/ou en carbone. 23. Nuclear fuel rod according to claim 22, in which each plug (6) is made of composite material comprising a ceramic matrix reinforced with ceramic reinforcing fibers, in particular a silicon carbide matrix reinforced with silicon carbide and/or carbon reinforcing fibers. 24. Crayon de combustible nucléaire selon la revendication 22 ou la revendication 23, comprenant deux éléments internes d’obturation (24), fermant chacun une extrémité respective de la doublure interne (18). 24. Nuclear fuel rod according to claim 22 or claim 23, comprising two internal sealing elements (24), each closing a respective end of the internal liner (18). 25. Crayon de combustible nucléaire selon l’une quelconque des revendications 22 à 24, dans lequel le gaz contenu dans la doublure interne (18) est par exemple de l’hélium et/ou la pression du gaz à l’intérieur de la doublure interne (18) est égale ou inférieure à 200 bars, de préférence égale ou inférieure à 100 bars, encore de préférence égale ou inférieure à 20 bars. 25. Nuclear fuel rod according to any one of claims 22 to 24, in which the gas contained in the internal lining (18) is for example helium and/or the pressure of the gas inside the internal lining (18) is equal to or less than 200 bars, preferably equal to or less than 100 bars, more preferably equal to or less than 20 bars.
PCT/EP2024/079239 2023-10-16 2024-10-16 Nuclear fuel rod cladding and method for producing such cladding Pending WO2025083082A1 (en)

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Citations (3)

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Publication number Priority date Publication date Assignee Title
US20090032178A1 (en) * 2004-06-07 2009-02-05 Gamma Engineering Corp. Multi-layered ceramic tube for fuel containment barrier and other applications in nuclear and fossil power plants
US20140153688A1 (en) * 2011-08-01 2014-06-05 Commissariat a I'energie atomique et aux energies Multilayer tube in ceramic matrix composite material, resulting nuclear fuel cladding and associated manufacturing processes
US20180254114A1 (en) * 2017-03-06 2018-09-06 Westinghouse Electric Company, Llc Method of manufacturing a reinforced nuclear fuel cladding using an intermediate thermal deposition layer

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090032178A1 (en) * 2004-06-07 2009-02-05 Gamma Engineering Corp. Multi-layered ceramic tube for fuel containment barrier and other applications in nuclear and fossil power plants
US20140153688A1 (en) * 2011-08-01 2014-06-05 Commissariat a I'energie atomique et aux energies Multilayer tube in ceramic matrix composite material, resulting nuclear fuel cladding and associated manufacturing processes
US20180254114A1 (en) * 2017-03-06 2018-09-06 Westinghouse Electric Company, Llc Method of manufacturing a reinforced nuclear fuel cladding using an intermediate thermal deposition layer

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