Plating apparatus

Abstract

To provide a plating apparatus capable of stably performing plating on the inner peripheral surface side of a coated tube.SOLUTION: A plating apparatus performs chromium plating on the inner peripheral surface of a cylindrical coated tube extending along an axis, and comprises a circulation section for circulating a chromium-containing plating solution from one end side of the coated tube to the other end side, an anode rod inserted into the coated tube, a cover electrode as a cathode made of a wire covering the outer peripheral surface of the coated tube, and a voltage application section for applying voltage between the anode rod and the cover electrode.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a plating apparatus. [Background technology]

[0002] Fuel rods used in nuclear reactors are composed of a fuel rod cladding tube (cladding tube) and fuel pellets packed inside the cladding tube. The cladding tubes of current light water moderated / light water cooled nuclear reactors are generally made of zirconium alloy, and a technology is known in which a chromium coating layer is formed on the outer surface by sputtering or plating. The method described in the following Patent Document 1 is known as a method for realizing this chromium coating.

[0003] The technology disclosed in the following Patent Document 1 includes a preparation step of placing a pipe material made of a zirconium alloy on an electrode material in a vacuum chamber and placing a target film made of chromium on the outer periphery of the pipe material, an electric field forming step of forming an electric field by applying a voltage between the electrode material and the target film, and a coating forming step of forming an amorphous coating on the surface of the pipe material by supplying argon and nitrogen into the vacuum chamber. Also, the technology disclosed in the following Patent Document 2 is known as a technology for forming a chromium coating. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2022-102894 A [Patent Document 2] Patent Publication No. 2022-057897 Summary of the Invention [Problem to be solved by the invention]

[0005] However, while the above method can coat the outer surface of the cladding tube, it is difficult to coat the inner surface with a consistent thickness. Also, although a method of immersing the cladding tube in a plating solution can be considered, the small diameter of the cladding tube makes it difficult to ensure stable plating because the plating solution does not reach the inside of the tube.

[0006] The present disclosure has been made to solve the above-mentioned problems, and has an object to provide a plating apparatus capable of stably performing plating on the inner surface side of a cladding tube. [Means for solving the problem]

[0007] In order to solve the above problems, the plating apparatus according to the present disclosure is a plating apparatus for applying chromium plating to an inner surface of a cylindrical coating tube extending along an axis, and includes: a circulation unit that circulates a plating solution containing chromium from one end side to the other end side of the coating tube; an anode bar inserted inside the coating tube; a cover electrode serving as a cathode made of a wire covering the outer surface of the coating tube; and a voltage application unit that applies a voltage between the anode bar and the cover electrode. Effect of the Invention

[0008] According to the plating apparatus of the present disclosure, plating can be stably performed on the inner peripheral surface side of the cladding tube. [Brief description of the drawings]

[0009] [Figure 1] 1 is an overall view showing a configuration of a plating apparatus according to an embodiment of the present disclosure; [Diagram 2] 1 is an enlarged cross-sectional view of a main portion of a plating apparatus according to an embodiment of the present disclosure. [Diagram 3] FIG. 1 is an overall view showing a first modified example of a plating apparatus according to an embodiment of the present disclosure. [Figure 4] FIG. 13 is an overall view showing a second modified example of a plating apparatus according to an embodiment of the present disclosure. [Diagram 5] FIG. 13 is an overall view showing a third modified example of a plating apparatus according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] (Configuration of plating device 1) Hereinafter, a plating apparatus 1 according to an embodiment of the present disclosure will be described with reference to Fig. 1 and Fig. 2. This plating apparatus 1 is an apparatus for applying chromium plating as a protective film to a nuclear fuel rod cladding tube (hereinafter, simply referred to as cladding tube 100) used in a nuclear reactor. In particular, it is suitably used for forming a plating film on the inner peripheral surface of the cladding tube 100.

[0011] As shown in Fig. 1 or 2, the cladding tube 100 has a cylindrical shape centered on an axis line X extending in the vertical direction. The cladding tube 100 is integrally formed of a zirconium alloy (zircaloy). When used in a nuclear reactor, the inside of the cladding tube 100 is filled with pellet-shaped nuclear fuel material.

[0012] As shown in FIG. 1, the plating apparatus 1 includes a circulation unit 10, an anode bar 20, a cover electrode 30, and a voltage application unit 40.

[0013] The circulating unit 10 is a member for supplying the plating liquid toward the inside of the cladding tube 100. The plating liquid is a liquid containing chromium trioxide, sulfuric acid, and potassium fluoride. Chromium trioxide is a base material for forming a plating film, sulfuric acid is a catalyst, and fluorine from potassium fluoride is used as a catalyst or as a remover for the oxide film formed on the surface of zircaloy.

[0014] The circulation unit 10 has a first tank 11, a second tank 12, a pump 13, and a reflux flow path 14. The first tank 11 and the second tank 12 are containers for storing the plating liquid. The first tank 11 is provided above the cladding tube 100 (i.e., on one side in the direction of the axis X). The second tank 12 is provided below the cladding tube 100 (i.e., on the other side in the direction of the axis X). Although not shown in detail, the first tank 11 and the second tank 12 are provided with a connection part that is connected to the cladding tube 100. As an embodiment of the connection part, for example, a pipe material that fits on the inner peripheral surface of the cladding tube 100 and a packing or an O-ring that seals leakage of the plating liquid between the pipe material and the cladding tube 100 are used.

[0015] A pump 13 for pumping the plating liquid is provided inside the second tank 12. Specifically, a diaphragm pump or a magnet pump is preferably used as the pump 13. The first tank 11 and the second tank 12 are connected by a reflux flow path 14. When the pump 13 is driven, the plating liquid flows inside the cladding tube 100 from the second tank 12 toward the first tank 11. The plating liquid that has reached the first tank 11 returns to the second tank 12 again via the reflux flow path 14. This flow occurs continuously, so that the plating liquid is constantly supplied to the inside of the cladding tube 100 for a predetermined time.

[0016] The anode rod 20 is an electrode disposed inside the covering tube 100. The anode rod 20 is provided at the position of the axis X, which is the central axis of the covering tube 100, and has a rod shape extending along the axis X. The material of the anode rod 20 is a metal material that has a rigidity capable of stably maintaining the posture and linearity at the position of the axis X and has a relatively small internal resistance (electrical resistance). Specifically, the material of the anode rod 20 can be an iron rod, a rod with a solder-coated surface of a brass core material, a rod with an iridium-coated surface of a titanium core material, or a solder rod with a lead / tin ratio of 6:4.

[0017] The cover electrode 30 is a member that functions as a cathode and covers the outer circumferential surface of the cladding tube 100. The cover electrode 30 is a net formed by weaving metal wires, and is desirably capable of expanding and contracting to a certain degree in accordance with the dimensions of the cladding tube 100. Prior to the plating operation, it is desirably to cover the cladding tube 100 with the cover electrode 30 and further fix the cover electrode 30 from the outer circumferential side with a jig (not shown) so that the cover electrode 30 and the outer circumferential surface of the cladding tube 100 are in uniform contact with each other.

[0018] The voltage application unit 40 applies a predetermined voltage between the anode bar 20 and the cover electrode 30. This causes a current to flow between the plating solution interposed between the anode bar 20 and the cover electrode 30 and the covering tube 100. Then, metal ions (chromium ions) in the plating solution cause an electrochemical reaction on the inner peripheral surface of the covering tube 100, forming a chromium plating film on the inner peripheral surface of the covering tube 100. The voltage application unit 40 controls the time for which the current flows, thereby appropriately determining the final thickness of the plating film.

[0019] The outer peripheral surface of the cladding tube 100 is also coated with a similar chromium film. The plating process for the outer peripheral surface is preferably performed by a sputtering method. An example of this type of method is disclosed in JP 2022-102894 A.

[0020] (Action and effect) Here, with the conventional sputtering technique, it is possible to apply a coating to the outer peripheral surface of the cladding tube 100, but there is a problem that it is difficult to apply a plating of a constant thickness to the inner peripheral surface. In addition, a method of immersing in a plating solution is also conceivable, but due to the small diameter of the cladding tube 100, the plating solution does not reach the inside, making it difficult to perform stable plating processing. Therefore, in this embodiment, the above-mentioned plating device 1 is used.

[0021] According to the above configuration, by applying a voltage between the anode bar 20 and the cover electrode 30, an electrochemical reaction occurs between the current flowing inside the covering tube 100 and the metal ions (chromium ions) in the plating solution. This makes it possible to apply chromium plating to the inner circumferential surface of the covering tube 100. In particular, since the cover electrode 30 is formed of a wire, the wire can be easily deformed and brought into close contact with the outer circumferential surface of the covering tube 100. This makes it possible to maintain a constant thickness of the plating film formed on the inner circumferential surface.

[0022] Moreover, according to the above configuration, the anode bar 20 is disposed at the position of the axis X, that is, at the central axis position of the cladding tube 100. This makes it possible to maintain a constant distance from the anode bar 20 to the inner peripheral surface of the cladding tube 100 over the entire circumferential direction. As a result, the voltage distribution between the anode bar 20 and the cover electrode 30 can be made uniform, and it becomes possible to make the thickness of the plating film uniform regardless of location. This further improves the quality of the final product.

[0023] Furthermore, according to the above configuration, since a net made of an elastic metal material is used as the cover electrode 30, the net can be made to adhere to the outer circumferential surface of the covering tube 100 while being stretched and contracted. This makes it possible to further uniformize the voltage distribution between the anode bar 20 and the cover electrode 30. As a result, it becomes possible to uniformize the thickness of the plating film with even higher accuracy. Also, since the net is stretchable, no large stress is generated between the net and the outer circumferential surface of the covering tube 100. This further reduces the possibility of scratching the outer circumferential surface.

[0024] In addition, according to the above configuration, the plating liquid flowing out from the second tank 12 flows through the inside of the cladding tube 100 toward the first tank 11. This allows clean plating liquid to be constantly supplied to the inside of the cladding tube 100. As a result, the thickness of the plating film becomes uniform, and the surface condition of the plating film can be kept smooth. This makes it possible to further improve the quality of the cladding tube 100.

[0025] Moreover, according to the above-mentioned configuration, by circulating the plating solution with the pump 13, it is possible to stably supply metal ions (chromium ions) in the plating solution and stabilize the temperature of the inner circumferential surface of the cladding tube 100 to be plated. This makes it possible to form the chromium coating more stably.

[0026] (Other embodiments) Although the embodiments of the present disclosure have been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and design changes and the like that do not depart from the gist of the present disclosure are also included.

[0027] For example, in the above embodiment, an example has been described in which a net formed of a metal wire is used as the cover electrode 30. However, the form of the cover electrode 30 is not limited to the above, and the cover electrode 30 may be formed by winding a metal wire in a spiral shape around the axis X on the outer circumferential surface of the covering tube 100. According to this configuration, the cover electrode 30 can be easily formed by simply winding a metal wire in a spiral shape on the outer circumferential surface of the covering tube 100. This makes it possible to keep the manufacturing costs and operating costs of the device low.

[0028] In the above embodiment, an example has been described in which the pump 13 for pumping the plating liquid inside the second tank 12 is provided. However, as a first modified example, as shown in FIG. 3, it is also possible to omit the pump 13. In this case, the plating liquid heated by the application of a voltage generates a natural convection current and flows in a direction from the second tank 12 toward the first tank 11. This method also makes it possible to obtain a stable plating film similar to that described above. On the other hand, from the viewpoint of shortening the time required for plating, a configuration using the pump 13 is advantageous.

[0029] Furthermore, in the above embodiment, an example was described in which the circulation section 10 is provided with the reflux flow path 14. However, as a second modified example, as shown in FIG. 4, it is also possible to adopt a configuration in which the reflux flow path 14 is not provided. In this case, a flow of the plating liquid due to its own weight occurs from the first tank 11 above to the second tank 12 below. By maintaining this flow for a certain period of time, a stable plating film can be formed as in the above-mentioned configuration. However, from the viewpoint of reducing the amount of plating liquid used, a configuration in which the plating liquid is reused by the reflux flow path 14 described above is advantageous.

[0030] In the above embodiment, the axis X of the cladding tube 100 extends in the vertical direction, and the attitude of the plating apparatus 1 is determined based on the vertical direction. However, the attitude of the plating apparatus 1 is not limited to the above, and a configuration shown as a third modified example in FIG. 5 may be adopted. In the example shown in the figure, the axis X coincides with the horizontal direction, and the first tank 11 and the second tank 12 are provided on both sides of the cladding tube 100 in the horizontal direction. The reflux flow path 14 connects the first tank 11 and the second tank 12 in the horizontal direction. With this configuration, it is possible to obtain the same effects as those described above.

[0031] Additionally, in the above embodiment, the pump 13 is provided in the second tank 12, and the plating liquid flows from the second tank 12 toward the first tank 11. However, the position where the pump 13 is provided is not limited to the above, and the pump may be disposed in the first tank 11. Furthermore, the direction in which the plating liquid flows is not limited to the above, and the plating liquid may flow from the first tank 11 through the inside of the cladding tube 100 to the second tank 12. Regardless of the configuration, the same effects as those described above can be obtained.

[0032] <Additional Notes> The plating apparatus 1 described in each embodiment can be understood, for example, as follows.

[0033] (1) A plating apparatus 1 according to a first embodiment is a plating apparatus 1 for applying chromium plating to an inner surface of a cylindrical coating tube 100 extending along an axis X, and includes a circulation unit 10 for circulating a plating solution containing chromium from one end side to the other end side of the coating tube 100, an anode bar 20 inserted inside the coating tube 100, a cover electrode 30 as a cathode made of a wire covering the outer surface of the coating tube 100, and a voltage application unit 40 for applying a voltage between the anode bar 20 and the cover electrode 30.

[0034] According to the above configuration, by applying a voltage between the anode bar 20 and the cover electrode 30, an electrochemical reaction occurs between the current in the plating solution flowing inside the cladding tube 100 and metal ions (chromium ions). As a result, the inner peripheral surface of the cladding tube 100 can be chrome plated.

[0035] (2) The plating apparatus 1 according to a second aspect is the plating apparatus 1 of (1), in which the anode bar 20 is provided at the position of the axis X and extends in the direction of the axis X.

[0036] According to the above configuration, the anode bar 20 is disposed at the position of the axis X, that is, at the central axis position of the cladding tube 100. This makes it possible to maintain a constant distance from the anode bar 20 to the inner peripheral surface of the cladding tube 100 over the entire circumferential direction. As a result, the voltage distribution between the anode bar 20 and the cover electrode 30 can be made uniform, and the thickness of the plating film can be made uniform regardless of location.

[0037] (3) The plating apparatus 1 of the third aspect is the plating apparatus 1 of (1) or (2), wherein the cover electrode 30 is a net formed of a metal material and having elasticity so as to come into contact with the outer peripheral surface of the coating tube 100.

[0038] According to the above configuration, since a net made of an elastic metal material is used as the cover electrode 30, the net can be stretched and made to adhere closely to the outer circumferential surface of the covering tube 100. This makes it possible to make the voltage distribution between the anode bar 20 and the cover electrode 30 more uniform.

[0039] (4) The plating apparatus 1 according to a fourth aspect is the plating apparatus 1 of (1) or (2), wherein the cover electrode 30 is a metallic wire formed of a metal material and spirally wound around the axis X on the outer circumferential surface of the coating tube 100.

[0040] According to the above-mentioned configuration, the cover electrode 30 can be easily formed by simply winding a metal wire in a spiral shape on the outer circumferential surface of the covering tube 100. This makes it possible to keep the manufacturing and operating costs of the device low.

[0041] (5) The plating apparatus 1 according to a fifth aspect is the plating apparatus 1 according to any one of the aspects (1) to (4), wherein the direction of the axis X is a vertical direction, and the circulation section 10 includes a first tank 11 provided on one side of the direction of the axis X above the cladding tube 100 and storing the plating liquid, and a second tank 12 provided on the other side of the direction of the axis X below the cladding tube 100 and storing the plating liquid that has passed through the inside of the cladding tube 100.

[0042] According to the above configuration, the plating liquid flowing out of the first tank 11 flows through the inside of the cladding tube 100 toward the second tank 12. This allows clean plating liquid to be constantly supplied to the inside of the cladding tube 100. As a result, the thickness of the plating film becomes uniform, and the surface condition of the plating film can be kept smooth.

[0043] (6) The plating apparatus 1 according to a sixth aspect is the plating apparatus 1 of (5), wherein the circulation section 10 further includes a pump 13 for pressure-pumping the plating liquid in a direction from the second tank 12 through the cladding tube 100 toward the first tank 11, and a reflux flow path 14 for connecting the first tank 11 and the second tank 12 and passing outside the cladding tube 100.

[0044] According to the above-mentioned configuration, the amount of plating liquid used can be minimized by circulating the plating liquid by the pump 13. This makes it possible to keep the operating costs and maintenance costs of the apparatus low. [Explanation of symbols]

[0045] Reference Signs List 1: Plating device 10: Circulation section 11: First tank 12: Second tank 13: Pump 14: Circulation flow path 20: Anode rod 30: Cover electrode 40: Voltage application section 100: Covering tube X: Axis

Claims

1. A plating apparatus for chrome plating an inner peripheral surface of a cylindrical cladding tube extending along an axis, comprising: a circulation unit that circulates a plating solution containing chromium from one end side to the other end side of the cladding tube; an anode rod inserted into the cladding tube; a cover electrode as a cathode made of a wire covering an outer circumferential surface of the covering tube; A voltage application unit that applies a voltage between the anode bar and the cover electrode; A plating apparatus comprising:

2. 2. The plating apparatus according to claim 1, wherein said anode rod is provided at a position on said axis and extends in said axial direction.

3. 3. The plating apparatus according to claim 1, wherein the cover electrode is a net made of a metallic material and has elasticity so as to come into contact with the outer circumferential surface of the covering tube.

4. 3. The plating apparatus according to claim 1, wherein the cover electrode is a metallic wire that is made of a metallic material and that is wound in a spiral shape around the axis on the outer circumferential surface of the covering tube.

5. The axial direction is a vertical direction, The circulation section includes: a first tank provided on one side of the cladding tube in the axial direction and configured to store the plating liquid; a second tank provided below the cladding tube on the other side in the axial direction, in which the plating liquid that has passed through the inside of the cladding tube is stored; 2. The plating apparatus of claim 1, further comprising:

6. The circulation section includes: a pump for pumping the plating solution in a direction from the second tank through the cladding tube toward the first tank; a reflux flow path connecting the first tank and the second tank and passing through the outside of the cladding tube; 6. The plating apparatus of claim 5, further comprising:

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