Fuel cladding tube manufacturing method, fuel rod manufacturing method, film forming apparatus, and fuel cladding tube

Abstract

To provide a method for manufacturing a fuel cladding tube capable of further improving corrosion resistance of a fuel rod, a method for manufacturing a fuel rod, a film forming apparatus, and a fuel cladding tube.SOLUTION: The film forming apparatus includes a vacuum chamber defining a film formation space inside, an electrode member provided in the film formation space and having a stage surface on which an end surface of the tube material abuts, a holding portion fixable to the stage surface and having a cylindrical member in contact with an entire circumference of an outer peripheral surface at an end portion of the tube material and a plug member in contact with an entire circumference of an inner peripheral surface at the end portion of the tube material, a target provided so as to face the outer peripheral surface of the tube material in the film formation space and made of a material containing chromium, and a gas supply portion supplying inert gas into the film formation space.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a method for manufacturing a fuel cladding tube, a method for manufacturing a fuel rod, a film forming apparatus, and a fuel cladding tube. [Background technology]

[0002] In nuclear reactors (light water reactors), fuel rods are formed by placing fuel pellets in fuel cladding tubes, and multiple fuel rods are bundled together to form a fuel assembly. Fuel cladding tubes are generally made of zirconium alloys. However, zirconium alloys are susceptible to oxidation and deformation when exposed to high-temperature steam in the event of an accident, so there is a need for improved accident resistance in these unlikely events. Furthermore, there is a trend toward higher fuel burnup in the future to reduce spent fuel. Therefore, there is a growing demand for improved corrosion resistance and wear resistance of fuel assemblies so that they can withstand long-term use in nuclear reactors.

[0003] For example, Patent Document 1 discloses a method for manufacturing a fuel cladding tube in which an amorphous coating is formed on the surface of a zirconium alloy. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-102894 Summary of the Invention [Problem to be solved by the invention]

[0005] Fuel rods are constructed by housing fuel pellets in fuel cladding tubes. At this time, both ends of the fuel cladding tube are welded and sealed. If the coating of the fuel cladding tube gets caught in the welds, there is a risk that the corrosion resistance of the fuel rods will deteriorate.

[0006] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a method for manufacturing a fuel cladding tube, a method for manufacturing a fuel rod, a film-forming device, and a fuel cladding tube that can further improve the corrosion resistance of a fuel rod. [Means for solving the problem]

[0007] In order to solve the above problems, the manufacturing method of a fuel cladding tube according to the present disclosure includes an installation step of arranging a cylindrical member that contacts the entire outer peripheral surface of the end of a pipe material made of a zirconium alloy, and a coating formation step of forming a coating on the outer peripheral surface of the pipe material after the installation step.

[0008] The method for manufacturing a fuel rod according to the present disclosure includes a step of obtaining the fuel cladding tube by the above-described method for manufacturing a fuel cladding tube, and an assembly step of, after the cutting step, accommodating fuel pellets and a spring inside the tube material and attaching and welding end caps to the ends of the tube material.

[0009] The film forming apparatus according to the present disclosure comprises a vacuum chamber defining a coating formation space therein, an electrode material provided in the coating formation space and having a stage surface against which the end face of the tubular material abuts, a holding unit that can be fixed to the stage surface and has a cylindrical member that contacts the outer peripheral surface of the end of the tubular material around the entire circumference and a plug member that contacts the inner peripheral surface of the end of the tubular material around the entire circumference, a target that is provided in the coating formation space so as to face the outer peripheral surface of the tubular material and is made of a material containing chromium, and a gas supply unit that supplies an inert gas into the coating formation space.

[0010] The fuel cladding tube according to the present disclosure comprises a pipe material made of a zirconium alloy and a coating formed only on the outer circumferential surface of the pipe material, excluding the ends of the pipe material. [Effects of the Invention]

[0011] According to the fuel cladding tube manufacturing method, fuel rod manufacturing method, film forming apparatus, and fuel cladding tube of the present disclosure, the corrosion resistance of the fuel rod can be further improved. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a longitudinal cross-sectional view showing the configuration of a fuel rod according to an embodiment of the present disclosure. [Figure 2] 1 is a flowchart illustrating steps in a method for manufacturing a fuel rod according to an embodiment of the present disclosure. [Figure 3] FIG. 1 is a vertical cross-sectional view showing a configuration of a manufacturing apparatus according to an embodiment of the present disclosure. [Figure 4] 1 is an enlarged view of a main portion of a longitudinal cross-sectional view showing a configuration of a manufacturing apparatus according to an embodiment of the present disclosure. [Figure 5] FIG. 1 is a cross-sectional view showing a configuration of a manufacturing apparatus according to an embodiment of the present disclosure. [Figure 6] FIG. 2 is an explanatory diagram showing a coating formation step in a method for manufacturing a fuel cladding tube according to an embodiment of the present disclosure. [Figure 7] 1 is a longitudinal cross-sectional view showing a configuration of a fuel cladding tube according to an embodiment of the present disclosure. FIG. [Figure 8] 1 is a cross-sectional view showing a configuration of a fuel cladding tube according to an embodiment of the present disclosure. FIG. [Figure 9] 1 is an enlarged view of a main portion of a longitudinal cross-sectional view showing a configuration of a manufacturing apparatus according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, a method S0 for manufacturing a fuel rod according to an embodiment of the present disclosure will be described with reference to the drawings.

[0014] <Fuel rod> As shown in Fig. 1, the fuel rod 1 to be manufactured is rod-shaped and arranged with its axis in the vertical direction inside the reactor core. The fuel rod 1 has a cylindrical fuel cladding tube 10, a spring 3 and fuel pellets 2 housed inside the fuel cladding tube 10, and end caps 4 attached to both ends.

[0015] The fuel pellets 2 are fissile materials whose main components are, for example, uranium or plutonium, and are used as a heat source for the reactor core. The fuel pellets 2 are molded into cylindrical pellets with a height and diameter of approximately 1 cm. These fuel pellets 2 are filled in the fuel cladding tube 10 in a stacked manner starting from the bottom. The uppermost fuel pellet 2 is pressed downward by a spring 3.

[0016] <Fuel cladding tube> The fuel cladding tube 10 includes a cylindrical pipe material 11 and a coating 20 formed on the outer peripheral surface 18 (outer surface) of the pipe material 11. The pipe material 11 is formed of a zirconium alloy. More specifically, the pipe material 11 contains zirconium and at least one chemical species selected from tin, niobium, iron, chromium, and oxygen. Even more specifically, the pipe material 11 contains 0 to 2 wt. % tin, 0 to 2 wt. % niobium, 0 to 0.4 wt. % iron, 0 to 0.5 wt. % chromium, 0 to 0.2 wt. % oxygen, and zirconium as the balance.

[0017] <Fuel rod manufacturing method> The method S0 for manufacturing a fuel rod according to this embodiment will be described with reference to the flowchart shown in Fig. 2. The method S0 for manufacturing a fuel rod includes a fuel cladding tube manufacturing step (method for manufacturing a fuel cladding tube) S1 and an assembly step S2.

[0018] <Method of manufacturing fuel cladding tube> The fuel cladding tube manufacturing method S1 is a method for manufacturing a fuel cladding tube 10 by forming a coating on the outer peripheral surface 18 of a tube material 11. The fuel cladding tube manufacturing method S1 in this embodiment includes a preparation step S11, an installation step S12, a coating formation step S13, and a cutting step S14.

[0019] <Preparation process> First, a preparation step S11 is performed. In this preparation step S11, a pipe material 11 is prepared.

[0020] <Installation process> After the preparation step S11 is performed, the installation step S12 is performed. The installation step S12 is a step of installing the tubular material 11 in the film formation apparatus 30. Before explaining the installation step S12 in detail, the detailed configuration of the film formation apparatus 30 will be explained. As shown in FIGS. 3 and 4, the film formation apparatus 30 according to this embodiment includes a vacuum chamber 31, an electrode material 33, a rotation drive unit 54, a holding unit 40, a target 50, and a gas supply unit (not shown).

[0021] The vacuum chamber 31 is provided so as to separate the outside from the inside. A coating formation space 32 is formed inside the vacuum chamber 31. The inside of the vacuum chamber 31, i.e., the coating formation space 32, can be evacuated.

[0022] The electrode material 33 is provided so as to apply a negative potential (bias voltage) to the tubular material 11. The electrode material 33 is provided in the coating formation space 32. Two electrode materials 33 are provided facing each other. The tubular material 11 can be placed so that the two electrode materials 33 sandwich the tubular material 11 between them. The electrode material 33 is provided with a stage surface 34, which is the surface on which the two electrode materials 33 face each other. The stage surface 34 is circular. As shown in FIG. 5 , multiple tubular materials 11 can be placed on the stage surface 34 in the circumferential direction of the axis O. Specifically, when the tubular material 11 is placed on the electrode material 33, the end surface 15 of the tubular material 11 abuts against the stage surface 34. Furthermore, the electrode material 33 is provided on the surface opposite the stage surface 34, and a connection portion 35 is provided to connect the electrode material 33 to the vacuum chamber 31. The electrode material 33 is made of a conductive material. The shape of the stage surface 34 is not limited to a circular shape.

[0023] The tubular material 11 can be provided so that its end face 15 abuts against the stage surface 34. In other words, the electrode material 33 can be provided on the tubular material 11 so that the end face 15 of the tubular material 11 abuts against the stage surface 34. Here, the direction extending from the end face 15 of the tubular material 11 in the extension direction of the tubular material 11 is defined as the axial direction. The tubular material 11 has end faces 15 on both ends in the axial direction. In addition, the region of the outer circumferential surface 18 of the tubular material 11 that is covered by the cylindrical member 41 described below is referred to as the end portion 12.

[0024] The rotation drive unit 54 is provided so as to be able to rotate the electrode material 33 around the axis O. The rotation drive unit 54 may be provided in the coating formation space 32, or may be provided elsewhere, i.e., outside the vacuum chamber 31. Various drive mechanisms such as an electric motor can be used as the rotation drive unit 54. A mechanism for rotating the tubular material 11 about its cylindrical center is also provided. However, a mechanism for rotating the tubular material 11 does not necessarily have to be provided.

[0025] The holding portion 40 is provided so as to enable the coating 20 not to be formed at desired locations on the outer peripheral surface 18 of the tubular material 11 in the coating formation process S13 described below. The holding portion 40 is provided in the coating formation space 32. The holding portion 40 can be arranged in contact with the entire outer peripheral surface 18 and inner peripheral surface 19 of the tubular material 11. The holding portion 40 can be fixed to the stage surface 34. The holding portion 40 is arranged in contact with the tubular material 11 and holds the tubular material 11 while being fixed to the stage surface 34. Multiple holding portions 40 are provided in the circumferential direction of the axis O. The holding portion 40 comprises a cylindrical member 41 and a plug member 44.

[0026] The cylindrical member 41 can be provided so as to cover the outer peripheral surface 18 of the pipe 11. The inner peripheral surface 41i of the cylindrical member 41 can be in contact with the outer peripheral surface 18 of the pipe 11 over the entire circumference. The plug member 44 can be provided so as to close the end 12 of the pipe 11. The plug member 44 is formed in a cylindrical shape. The outer peripheral surface 44o of the plug member 44 can be in contact with the inner peripheral surface 19 of the pipe 11 over the entire circumference.

[0027] The cylindrical member 41 and the plug member 44 have base ends 43, 46 that can contact the stage surface 34, and tip ends 42, 45 that are opposite the base ends 43, 46 in the axial direction. When the cylindrical member 41 and the plug member 44 are both installed on the tubular material 11 and the stage surface 34, the tip 42 of the cylindrical member 41 is located farther away from the end face 15 of the tubular material 11 toward the center in the extension direction of the tubular material 11 than the tip 45 of the plug member 44. In other words, the distance between the base end 43 and the tip 42 of the cylindrical member 41 is greater than the distance between the base end 46 and the tip 45 of the plug member 44. Note that the base ends 43, 46 of the cylindrical member 41 and the plug member 44 are flush with the end face 15 of the tubular material 11 when the tubular material 11 is installed on the electrode material 33.

[0028] The target 50 is provided as a sputtering evaporation source. A negative potential (bias voltage) can be applied to the target 50. The target 50 is provided in the coating formation space 32. The target 50 is provided in contact with the vacuum chamber 31. The target 50 is provided so as to face the outer peripheral surface 18 of the tubular material 11 when the tubular material 11 is in contact with the holder 40 and the stage surface 34. The target film 51 is provided on a surface facing the outer peripheral surface 18 of the tubular material 11. The target 50 is also provided at a radial distance in the axial direction from the outer peripheral surface 18 of the tubular material 11. The target 50 includes the target film 51 and a magnet 52. The target film 51 is made of a material containing chromium. The magnet 52 is provided on the surface in contact with the vacuum chamber 31. That is, the magnet 52 is provided on the outer peripheral side of the target 50 so as to be the back surface of the target film 51 when viewed from the tubular material 11.

[0029] The targets 50 are provided in plural and spaced apart from one another in the axial direction. Also, the targets 50 are provided in plural and spaced apart from one another in the circumferential direction as viewed from the axial direction. More specifically, when viewed from the axial direction, if the circumferential position of any given target 50 is set to 0°, it is desirable that another target 50 adjacent to it in the axial direction be provided at a circumferential position 180° apart. Note that these circumferential positions are merely examples and can be changed as appropriate depending on the design and specifications.

[0030] Furthermore, at least a portion of the axial end portions 12 of a pair of axially adjacent targets 50 overlap each other in the axial direction. In other words, the pair of targets 50 overlap in the axial direction. Furthermore, the targets 50 located on both ends in the axial direction extend further outward than the tip 42 of the cylindrical member 41 in the axial direction. In other words, the tip 42 of the cylindrical member 41 is covered by the targets 50 and the magnets 52 from the radially outer side.

[0031] 4 shows that a bias voltage is applied to the electrode material 33 and the target 50 by one power supply, but this is not limiting. For example, the electrode material 33 and the target 50 may be connected to separate power supplies, and separate bias voltages may be applied to each. Also, for example, a configuration may be adopted in which a bias voltage is applied only to the target film 51.

[0032] The gas supply unit is configured to supply gas into the coating formation space 32. The gas supply unit is configured to supply an inert gas. That is, the gas supply unit is composed of a tank storing the inert gas, a pipe connecting the tank to the coating formation space 32, an on-off valve provided on the pipe, and the like. The gas supply unit of this embodiment is configured to supply argon, which is an inert gas, and nitrogen. The gas supply unit may be configured to supply only argon, or may be configured to supply other elements.

[0033] The installation step S12 is a step of installing the tubular material 11 in the film forming apparatus 30. In the installation step S12, the following steps a) to e) are performed in any order.

[0034] a) The cylindrical member 41 is arranged so that the inner peripheral surface 41i of the cylindrical member 41 is in contact with the entire outer peripheral surface 18 at the end 12 of the tubular material 11. At this time, the end surface 15 of the tubular material 11 and the base end 43 of the cylindrical member 41 are flush with each other. b) The plug member 44 is positioned so that the outer surface 44o of the plug member 44 is in contact with the entire inner surface 19 at the end 12 of the tubular material 11. At this time, the end surface 15 of the tubular material 11 and the base end 46 of the plug member 44 are flush with each other. c) The cylindrical member 41 is fixed onto the electrode material 33. That is, the base end 43 of the cylindrical member 41 and the stage surface 34 are fixed together. d) The plug member 44 is fixed onto the electrode member 33. That is, the base end 46 of the plug member 44 and the stage surface 34 are fixed together. e) The tubular material 11 is fixed onto the electrode material 33. That is, the end surface 15 of the tubular material 11 and the stage surface 34 are fixed together.

[0035] Steps a) to e) are performed in any order, but as an example, they are performed in the following order: After performing steps a) and b), steps c) to e) are performed simultaneously. That is, after the holding portion 40 is installed on the tubular material 11, the tubular material 11 and the holding portion 40 are fixed onto the electrode material 33 at the same time. As another example, for example, after performing steps c) and d), steps a), b), and e) are performed simultaneously. That is, after the holding portion 40 is fixed onto the electrode material 33, the tubular material 11 is installed by fitting it into the holding portion 40.

[0036] It is sufficient that there is at least one location for fixing to the stage surface 34. For example, as long as the end surface 15 of the tubular material 11 is fixed to the stage surface 34, the base end 43 of the cylindrical member 41 and the stage surface 34 and the 46 of the plug member 44 do not need to be fixed to each other.

[0037] <Film formation process> After the installation step S12 is performed, the coating formation step S13 is performed. The coating formation step S13 is a step of forming a coating 20 on the outer peripheral surface 18 of the pipe material 11. In the coating formation step S13, while argon and nitrogen are supplied to the coating formation space 32 by the gas supply unit, a negative potential relative to the vacuum chamber 31 is applied to the target 50 by power supply from the power source. The applied potential and the magnetic field action of the magnet 52 create a high-concentration argon plasma near the surface of the target film 51, and chromium elements in the target 50 are released by sputtering due to irradiation with argon ions (Ar+). At the same time, a negative potential or zero potential (bias voltage) relative to the vacuum chamber 31 is applied to the pipe material 11 (electrode material 33) by power supply from the power source.

[0038] At this time, the partial pressure of argon is set to 0.1 Pa or less, more preferably 0.01 Pa or more and 0.1 Pa or less. The partial pressure of nitrogen is set to a range of more than 0 Pa and 0.06 Pa or less. The temperature of the coating formation space 32 is set to 150°C or more and 200°C or less. As will be described in detail later, if the bias voltage is 150 V or more, the chromium will crystallize, and an amorphous coating 20 cannot be obtained.

[0039] Under these conditions, as shown in Figure 6, nitrogen molecules collide with electrons (plasma electrons) emitted by the plasma in the coating formation space 32, forming nitrogen ions (N+). Chromium elements (Cr) emitted by sputtering are deposited on the outer peripheral surface 18 of the pipe material 11, and at the same time, argon ions (Ar+) and nitrogen ions (N+) are electrically attracted by the bias voltage, and nitrogen elements (N) are supplied while imparting energy to the deposited chromium elements (Cr), thereby forming a coating 20 with an amorphous structure. In the coating formation step S13, the coating 20 is formed on the outer peripheral surface 18 of the pipe material 11 while the electrode material 33 and the pipe material 11 are rotated by the rotation drive unit 54.

[0040] <Cutting process> After the coating formation step S13 is performed, the cutting step S14 is performed. The cutting step S14 is a step of cutting the tubular material 11. In the cutting step S14, the tubular material 11 is cut along a plane perpendicular to the axial direction at a position between the tip 42 of the cylindrical member 41 and the tip 45 of the plug member 44. In this embodiment, the cylindrical member 41 is removed from the tubular material 11, and then the tubular material 11 is cut. However, before cutting the tubular material 11, the cylindrical member 41 may be removed from the tubular material 11 or may remain in place. That is, in the cutting step S14, the cylindrical member 41 and the tubular material 11 may be cut while the cylindrical member 41 is still attached to the tubular material 11, or the tubular material 11 may be cut after the cylindrical member 41 is removed from the tubular material 11.

[0041] When the cylindrical member 41 and the tubular material 11 are cut, the cylindrical member 41 that is in contact with the tubular material 11 on the side where the coating 20 is formed is removed. This is performed for both end portions 12 of the tubular material 11. In this way, the fuel cladding tube 10 shown in Figures 7 and 8 can be obtained.

[0042] <Assembly process> After the cutting step S14 is performed, the assembly step S2 is performed. The assembly step S2 is a step of assembling the fuel rod 1. The assembly step S2 is performed as follows: An end cap 4 is welded to one axial end 12 of the fuel cladding tube 10 manufactured in the fuel cladding tube manufacturing step S1. Fuel pellets 2 are placed inside the fuel cladding tube 10 from the other axial end 12 of the fuel cladding tube 10. A spring 3 is placed inside the fuel cladding tube 10 from the other axial end 12 of the fuel cladding tube 10. An end cap 4 different from the end cap 4 welded to the one axial end 12 is welded to the other axial end 12 of the fuel cladding tube 10. In this way, the fuel rod 1 shown in FIG. 1 can be obtained.

[0043] <Action and effect> According to the above-described fuel cladding tube manufacturing method S1, in the coating formation step S13, the outer peripheral surface 18 of the end 12 of the tubular member 11 is covered over its entire circumference with the cylindrical member 41. By performing the coating formation step S13 in this state to form the coating 20 on the outer peripheral surface 18 of the tubular member 11, the coating 20 is formed only on the outer peripheral surface 18 of the tubular member 11 in the portion not covered by the cylindrical member 41. That is, the coating 20 is formed over the entire circumference only in the region excluding the end 12 of the tubular member 11. In other words, the coating 20 is not formed over the entire circumference of the outer peripheral surface 18 of the end 12 of the tubular member 11, i.e., the portion that will be welded to the end cap 4 when the fuel rod 1 is formed. Therefore, a fuel cladding tube 10 can be manufactured in which the coating 20 is not caught in the welding process used to manufacture the fuel rod 1.

[0044] Furthermore, according to the fuel cladding tube manufacturing method S1 of this embodiment, the end 12 of the tubular material 11 is in contact with the outer peripheral surface 44o of the plug member 44 around the entire inner peripheral surface 19. In this state, the end 12 of the tubular material 11 is held from the outer peripheral surface 18 by the cylindrical member 41 and from the inner peripheral surface 19 by the plug member 44. This makes it possible to hold the tubular material 11 more stably in the coating formation step S13. Furthermore, since the cylindrical member 41 and the plug member 44 are provided on both end portions 12 of the tubular material 11, even gases and the like cannot easily enter the interior of the tubular material 11. This makes it possible to prevent elements constituting the coating 20 from entering the interior of the tubular material 11 in the coating formation step S13.

[0045] Furthermore, according to the manufacturing method S1 of the fuel cladding tube of this embodiment, the plug members 44, which have a length shorter than the length of the cylindrical members 41 in the extension direction of the tube member 11, are arranged around the entire inner circumferential surface 19 of the end portion 12 of the tube member 11. This makes it possible to shorten the length of the tube member 11 that is cut in the cutting step S14. In other words, it is possible to shorten the length of the tube member 11 that is removed. By reducing the amount of the tube member 11 that is removed, the fuel cladding tube 10 can be manufactured more economically. Furthermore, the cylindrical members 41 and plug members 44 that were not cut in the cutting step S14 can be reused.

[0046] Furthermore, according to the manufacturing method S1 for a fuel cladding tube of this embodiment, in the cutting step S14, the tube material 11 is cut in the axial direction between the tip 42 of the cylindrical member 41 and the tip 45 of the plug member 44. As a result, a tube material 11 is formed in which no plug member 44 remains inside the tube material 11, the inner circumferential surface 19 is free from scratches, and the coating 20 is formed, i.e., the fuel cladding tube 10.

[0047] Furthermore, according to the fuel cladding tube manufacturing method S1 of this embodiment, the coating 20 can be formed on the outer peripheral surface 18 of the tubular material 11 by using sputtering in the coating formation step S13. This makes it possible to obtain a coating structure with improved adaptability to deformation. As a result, even if the tubular material 11 expands or deforms, the coating 20 can easily adapt to the deformation, and the life of the fuel cladding tube 10 can be maintained even longer.

[0048] Furthermore, according to the manufacturing method S1 for a fuel cladding tube of this embodiment, in the coating formation step S13, the coating 20 is formed on the outer peripheral surface 18 of the tubular material 11 while rotating the electrode material 33 and the tubular material 11 around the axis O. By performing the coating formation step S13 while rotating the tubular material 11, the coating 20 is formed sequentially in the circumferential direction on the outer peripheral surface 18 of the tubular material 11. As a result, even if the target 50 is not installed over the entire circumferential direction, it is possible to form a coating 20 of a uniform thickness on the outer peripheral surface 18 of the tubular material 11. Furthermore, even when the tubular material 11 is rotated in this manner, the tubular material 11 is held by the holder 40 and the electrode material 33, so that the tubular material 11 can be stably installed without falling off.

[0049] According to the fuel cladding tube 10 of this embodiment, the coating 20 is formed around the entire outer circumferential surface 18 only in the region excluding the end 12 of the tubular material 11. In other words, the coating 20 is not formed around the entire outer circumferential surface 18 of the end 12 of the tubular material 11, i.e., the portion that is welded when the fuel rod 1 is formed. Therefore, it is possible to prevent the coating 20 from being caught in the welding in the manufacture of the fuel rod 1. Furthermore, it is possible to improve the corrosion resistance of the fuel rod 1.

[0050] According to the fuel rod manufacturing method S0 of this embodiment, a fuel rod 1 can be manufactured using a fuel cladding tube 10 in which the coating 20 is not formed on the end 12 of the tube material 11. Therefore, in the assembly step S2, the coating 20 is not caught in the welding. That is, when the end cap 4 is attached to the end 12 of the tube material 11 and welded, the coating 20 is not caught in the welding. Because the coating 20 is not caught in the welding, it is possible to avoid a situation in which chromium and zirconium are mixed together, for example. Therefore, the corrosion resistance of the fuel rod 1 can be improved.

[0051] According to the film-forming apparatus 30 of this embodiment, after the installation step S12 has been performed, the outer peripheral surface 18 of the end 12 of the tubular material 11 is covered over the entire circumference with the cylindrical member 41. By forming the coating 20 on the outer peripheral surface 18 of the tubular material 11 in this state, the coating 20 is formed over the entire circumference only in the area excluding the end 12 of the tubular material 11. In other words, the coating 20 is not formed over the entire circumference of the outer peripheral surface 18 of the end 12 of the tubular material 11, i.e., the portion that is welded when the fuel rod 1 is formed. Therefore, according to the film-forming apparatus 30 of this embodiment, it is possible to manufacture a fuel cladding tube 10 in which the coating 20 is not caught in the welding process in the manufacture of the fuel rod 1.

[0052] Furthermore, the film-forming apparatus 30 of this embodiment can form an amorphous coating 20 on the outer peripheral surface 18 of the tubular material 11. This makes it possible to obtain a coating structure with improved adaptability to deformation. As a result, even if the tubular material 11 expands or deforms, the coating 20 can easily adapt to the deformation, and the life of the fuel cladding tube 10 can be maintained even longer.

[0053] Furthermore, according to the film forming apparatus 30 of this embodiment, a plug member 44 having a length shorter than the length of the cylindrical member 41 in the extension direction of the tubular material 11 is arranged around the entire inner surface 19 of the end portion 12 of the tubular material 11.

[0054] Furthermore, according to the film forming apparatus 30 of this embodiment, the coating 20 is formed on the outer peripheral surface 18 of the tubular material 11 while rotating the electrode material 33 and the tubular material 11 around the axis O. By forming the coating 20 while rotating the tubular material 11, the coating 20 is formed sequentially in the circumferential direction on the outer peripheral surface 18 of the tubular material 11. As a result, even if the target 50 is not installed over the entire circumferential direction, a coating 20 of uniform thickness can be formed on the outer peripheral surface 18 of the tubular material 11. Furthermore, even when the tubular material 11 is rotated in this manner, the tubular material 11 is held by the holding portion 40 and the electrode material 33, so that the tubular material 11 can be stably installed without falling off.

[0055] Furthermore, according to the film-forming apparatus 30 of this embodiment, it is possible to arrange a plurality of tubular materials 11 on the stage surface 34 in the circumferential direction of the axis O. This makes it possible to simultaneously form the coating 20 on the outer peripheral surface 18 of a plurality of tubular materials 11. Therefore, it is possible to form the coating 20 on the outer peripheral surface 18 of the tubular material 11 more efficiently in terms of time. Furthermore, by shortening the sputtering time, it is possible to suppress a decrease in the thickness of the target film 51, and it is possible to manufacture the fuel cladding tube 10 more economically.

[0056] <Other embodiments> The above describes in detail the embodiments of the present disclosure with reference to the drawings, but the specific configuration is not limited to this embodiment, and design changes and the like are also included within the scope that does not deviate from the gist of the present disclosure.

[0057] For example, as shown in FIG. 9 , the fuel cladding tube manufacturing method S1 or the film-forming apparatus 30 may be configured such that only a cylindrical member 41 is provided without a plug member 44. The holding unit 40A may also include a disk member 47 connected to the base end 43 of the cylindrical member 41 and arranged to close the base end 43. The disk member 47 is made of a conductive material. The holding unit 40A has a cap shape formed by the cylindrical member 41 and the disk member 47. When using such a holding unit 40A, the end face 15 and the stage surface 34 are not in direct contact with each other when the tubular material 11 is placed in the film-forming apparatus 30. This allows the length of the tubular material 11 to be cut to be shorter. In other words, the length of the tubular material 11 to be removed can be shortened. Reducing the amount of tubular material 11 to be removed allows for more economical production of the fuel cladding tube 10.

[0058] Furthermore, the holding portion 40A may further include a plug member 44 connected to the disk member 47 at its base end 46.

[0059] Furthermore, the number of targets 50 is not limited to a plurality, and only one target may be provided.

[0060] Furthermore, the target 50 does not have to be provided so as to be in direct contact with the vacuum chamber 31. For example, the target 50 may be provided so as to be in contact with some kind of device provided in connection with the vacuum chamber 31.

[0061] Also, only one electrode material 33 may be provided. Even in a configuration in which the holder 40 and the tube material 11 are fixed to the stage surface 34 of one electrode material 33, a fuel cladding tube 10 similar to the fuel cladding tube 10 manufactured in the embodiment of the present disclosure can be manufactured.

[0062] Although the present disclosure describes the coating formation by sputtering, the coating formation method is not limited to this. For example, even if the coating formation step S13 is performed by plating, a fuel cladding tube 10 similar to the fuel cladding tube 10 manufactured in the embodiment of the present disclosure can be manufactured.

[0063] Furthermore, in the cutting step S14, the plug member 44 may be removed from the pipe material 11 when the pipe material 11 is being cut. That is, in the cutting step S14, the pipe material 11 may be cut after the plug member 44 has been removed from the pipe material 11.

[0064] <Additional Notes> The fuel cladding tube manufacturing method S1, the fuel rod manufacturing method S0, the film forming apparatus 30, and the fuel cladding tube 10 according to the embodiment of the present disclosure can be understood, for example, as follows.

[0065] (1) The manufacturing method S1 of the fuel cladding tube according to the first embodiment includes an installation step S12 of arranging a cylindrical member 41 that contacts the entire outer surface 18 of the end 12 of a pipe material 11 made of a zirconium alloy, and a coating formation step S13 of forming a coating 20 on the outer surface 18 of the pipe material 11 after the installation step S12.

[0066] According to the above configuration, in the coating formation step S13, the outer peripheral surface 18 of the end 12 of the tubular material 11 is covered over the entire circumference with the cylindrical member 41. By forming the coating 20 on the outer peripheral surface 18 of the tubular material 11 in this state, the coating 20 is formed over the entire circumference only in the area excluding the end 12 of the tubular material 11. Therefore, according to this embodiment, it is possible to manufacture a fuel cladding tube 10 in which the coating 20 is not caught in the welding in the manufacture of the fuel rod 1.

[0067] (2) The second aspect of the manufacturing method S1 for a fuel cladding tube is the manufacturing method S1 for a fuel cladding tube of (1), and in the installation step S12, a plug member 44 is further placed in contact with the entire inner surface 19 of the end 12 of the tube material 11.

[0068] According to the above configuration, the end 12 of the tubular material 11 is in contact with the plug member 44 around the entire circumference of the inner circumferential surface 19. In this state, the end 12 of the tubular material 11 is held from the outer circumferential surface 18 by the cylindrical member 41 and from the inner circumferential surface 19 by the plug member 44. This makes it possible to hold the tubular material 11 more stably in the coating formation step S13. Furthermore, by providing the cylindrical member 41 and the plug member 44 at the end 12 of the tubular material 11, it is possible to prevent elements constituting the coating 20 from entering the interior of the tubular material 11 in the coating formation step S13.

[0069] (3) The manufacturing method S1 for a fuel cladding tube according to the third aspect is the manufacturing method S1 for a fuel cladding tube of (2), in which the tip 42 of the cylindrical member 41 is positioned further away from the end face 15 of the tube material 11 toward the center of the extension direction of the tube material 11 than the tip 45 of the plug member 44.

[0070] According to the above configuration, the plug member 44, which has a length shorter than the length of the cylindrical member 41 in the extension direction of the tubular material 11, is arranged around the entire inner circumferential surface 19 of the end portion 12 of the tubular material 11. This allows the length of the tubular material 11 to be cut to a shorter length in the cutting step S14 described below.

[0071] (4) The manufacturing method S1 for a fuel cladding tube according to a fourth aspect is the manufacturing method S1 for a fuel cladding tube according to (2) or (3), and further includes, after the coating forming step S13, a cutting step S14 for obtaining a fuel cladding tube 10 by cutting the tubular material 11 and the cylindrical member 41 along a plane perpendicular to the extending direction of the tubular material 11 at a position between the tip 42 of the cylindrical member 41 and the tip 45 of the plug member 44 in the extending direction of the tubular material 11.

[0072] According to the above configuration, a pipe material 11 is formed on which the coating 20 is formed, with no contact portion with the plug member 44 remaining inside the pipe material 11. By removing the plug member 44 by cutting the pipe material 11 in this way, a fuel cladding tube 10 can be manufactured in which the inner peripheral surface 19 of the pipe material 11 is not damaged.

[0073] (5) A fifth aspect of the manufacturing method S1 for a fuel cladding tube is a manufacturing method S1 for a fuel cladding tube according to any one of (1) to (4), in which the coating formation step S13 is a step of forming a coating 20 on the surface of the tube material 11 by supplying an inert gas while applying a voltage between an electrode material 33 on which the tube material 11 is placed and a target 50 made of chromium.

[0074] According to the above-described configuration, the coating 20 made of chromium can be formed on the outer circumferential surface 18 of the pipe material 11. This allows the life of the fuel cladding tube 10 to be maintained long.

[0075] (6) A sixth aspect of the manufacturing method S1 for a fuel cladding tube is the manufacturing method S1 for a fuel cladding tube of any one of (2) to (5), in which the installation step S12 further includes a step of installing the tubular material 11 on the electrode material 33, the cylindrical member 41 and the plug member 44 are fixable to the electrode material 33, and in the coating formation step S13, the coating 20 is formed while rotating the electrode material 33 around an axis O extending in the extension direction of the tubular material 11.

[0076] According to the above configuration, in the coating formation step S13, the coating 20 is formed while rotating the electrode material 33 and the pipe material 11 around the axis O. This causes the coating 20 to be formed sequentially on the outer peripheral surface 18 of the pipe material 11. Therefore, the coating 20 of a uniform thickness can be formed on the outer peripheral surface 18 of the pipe material 11.

[0077] (7) A manufacturing method S0 for a fuel rod according to a seventh aspect includes a step of obtaining the fuel cladding tube 10 by a manufacturing method S1 for a fuel cladding tube described in any one of (1) to (6), and an assembly step S2 after the step of obtaining the fuel cladding tube 10, in which fuel pellets 2 and a spring 3 are placed inside the tube material 11 and an end cap 4 is attached to the end 12 of the tube material 11 and welded.

[0078] According to the above configuration, the fuel rod 1 can be manufactured using the fuel cladding tube 10 in which the coating 20 is not formed on the end 12 of the tube material 11. Therefore, when the end cap 4 is attached to the end 12 of the tube material 11 and welded, the coating 20 is not caught in the welding. Therefore, the corrosion resistance of the fuel rod 1 can be improved.

[0079] (8) The film forming apparatus 30 according to the eighth aspect comprises a vacuum chamber 31 defining a coating formation space 32 therein, an electrode material 33 provided in the coating formation space 32 and having a stage surface 34 against which the end face 15 of the tubular material 11 abuts, a holding unit 40 that can be fixed to the stage surface 34 and has a cylindrical member 41 that contacts the entire outer surface 18 at the end 12 of the tubular material 11, and a plug member 44 that contacts the entire inner surface 19 at the end 12 of the tubular material 11, a target 50 that is provided in the coating formation space 32 so as to face the outer surface 18 of the tubular material 11 and is made of a material containing chromium, and a gas supply unit that supplies an inert gas into the coating formation space 32.

[0080] According to the above configuration, the outer peripheral surface 18 of the end 12 of the tubular member 11 is covered over the entire circumference by the cylindrical member 41. By forming the coating 20 on the outer peripheral surface 18 of the tubular member 11 in this state, the coating 20 is formed over the entire circumference only in the area excluding the end 12 of the tubular member 11. Therefore, according to this embodiment, it is possible to manufacture a fuel cladding tube 10 in which the coating 20 is not caught in the welding in the manufacture of the fuel rod 1.

[0081] (9) The film forming apparatus 30 according to the ninth aspect is the film forming apparatus 30 of (8), in which the tip 42 of the cylindrical member 41 is positioned farther from the stage surface 34 in the extension direction of the tubular material 11 than the tip 45 of the plug member 44.

[0082] According to the above configuration, the plug member 44, which has a length shorter than the length of the cylindrical member 41 in the extension direction of the tube member 11, is arranged around the entire inner circumferential surface 19 of the end portion 12 of the tube member 11. This makes it possible to easily remove the plug member 44 when forming the fuel cladding tube 10.

[0083] (10) The film forming apparatus 30 according to the tenth aspect is the film forming apparatus 30 of (8) or (9), further comprising a rotational drive unit 54 that rotates the electrode material 33 around an axis O extending in the extension direction of the pipe material 11.

[0084] According to the above configuration, the coating 20 is formed while rotating the electrode material 33 and the tubular material 11 around the axis O. This allows the coating 20 to be formed sequentially on the outer peripheral surface 18 of the tubular material 11. Therefore, the coating 20 of a uniform thickness can be formed on the outer peripheral surface 18 of the tubular material 11.

[0085] (11) The film forming apparatus 30 according to the eleventh aspect is the film forming apparatus 30 according to any one of (8) to (10), in which the holding portions 40 are provided in multiple positions around the axis O extending in the extension direction of the pipe material 11.

[0086] According to the above configuration, it is possible to simultaneously form the coating 20 on a plurality of pipe materials 11. Therefore, the coating 20 can be formed on the outer circumferential surface 18 of the pipe material 11 more efficiently.

[0087] (12) A fuel cladding tube 10 according to a twelfth aspect comprises a pipe material 11 made of a zirconium alloy and a coating 20 formed only on the outer surface 18 of the pipe material 11, excluding the end 12 of the pipe material 11.

[0088] According to the above configuration, the coating 20 is formed around the entire outer circumferential surface 18 only in the region excluding the end 12 of the tube material 11. Therefore, the coating 20 can be prevented from being caught in the welding in the manufacturing of the fuel rod 1. [Explanation of symbols]

[0089] 1 fuel rod 2 fuel pellets 3 Spring 4 end cover 10 Fuel cladding tube 11 Piping material 12 End 15 End face 18 Outer surface 19 Inner surface 20 Coating 30 Film deposition equipment 31 Vacuum Chamber 32 Film formation space 33 Electrode material 34 Stage surface 35 Connection 40, 40A holding part 41 Cylindrical member 41i Inner surface 42 Tip 43 Proximal end 44 Plug member 44o outer surface 45 Tip 46 Proximal end 47 Disc member 50 targets 51 Target membrane 52 Magnet 54 Rotation drive unit О axis S0 Fuel rod manufacturing method S1 Fuel cladding tube manufacturing process (Fuel cladding tube manufacturing method) S11 Preparation process S12 Installation process S13 Film formation process S14 Cutting process S2 Assembly process

Claims

1. an installation step of disposing a cylindrical member in contact with the entire outer circumferential surface of the end of the pipe material made of zirconium alloy; a coating forming step of forming a coating on the outer peripheral surface of the pipe material after the installing step; A method for manufacturing a fuel cladding tube, comprising:

2. The method for manufacturing a fuel cladding tube according to claim 1 , wherein the step of installing further comprises disposing a plug member that contacts the entire inner circumferential surface of the end of the tube.

3. 3. The method for manufacturing a fuel cladding tube according to claim 2, wherein the tip of the cylindrical member is positioned farther away from the end face of the tube toward the center of the tube in the extending direction than the tip of the plug member.

4. 3. The method for manufacturing a fuel cladding tube according to claim 2, further comprising, after the coating forming step, a cutting step of cutting the tubular material and the cylindrical member along a plane perpendicular to the extending direction of the tubular material at a position between the tip of the cylindrical member and the tip of the plug member in the extending direction of the tubular material to obtain a fuel cladding tube.

5. 2. The method for manufacturing a fuel cladding tube according to claim 1, wherein the coating formation step is a step of forming a coating on the surface of the tube material by supplying an inert gas while applying a voltage between an electrode material on which the tube material is placed and a target made of chromium.

6. The step of installing further includes the step of installing the pipe material on an electrode material, the cylindrical member and the plug member are fixable to the electrode material, 3. The method for manufacturing a fuel cladding tube according to claim 2, wherein in the coating forming step, the coating is formed while rotating the electrode material around an axis extending in the extending direction of the tube material.

7. a step of obtaining the fuel cladding tube by the method of manufacturing the fuel cladding tube according to any one of claims 1 to 6; a fuel rod manufacturing method including, after the step of obtaining the fuel cladding tube, an assembly step of accommodating fuel pellets and a spring inside the tubular material and attaching and welding end caps to the ends of the tubular material.

8. a vacuum chamber defining a coating formation space therein; an electrode material provided in the coating formation space and having a stage surface against which an end surface of a tubular material abuts; a holding portion that is fixable to the stage surface and has a cylindrical member that contacts the outer peripheral surface of the end portion of the tubular material over the entire circumference, and a plug member that contacts the inner peripheral surface of the end portion of the tubular material over the entire circumference; a target provided in the coating formation space so as to face the outer peripheral surface of the pipe material and made of a material containing chromium; a gas supply unit that supplies an inert gas into the coating formation space; A film forming apparatus comprising:

9. 9. The film deposition apparatus according to claim 8, wherein the tip of the cylindrical member is positioned farther from the stage surface in the extending direction of the tubular material than the tip of the plug member.

10. The film deposition apparatus according to claim 8 , further comprising a rotation drive unit that rotates the electrode material about an axis extending in an extension direction of the tubular material.

11. The film deposition apparatus according to claim 8 , wherein a plurality of the holding portions are provided in a circumferential direction of an axis extending in an extension direction of the tubular member.

12. a pipe material made of a zirconium alloy; a coating formed only on an area of ​​the outer circumferential surface of the pipe material excluding the end portion of the pipe material; A fuel cladding tube comprising:

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