Method for manufacturing zirconium alloy cladding tube

Abstract

One embodiment provides a method for manufacturing a zirconium alloy cladding tube that suppresses changes in the microstructure of a zirconium alloy base material caused by process heat generated during a metal coating film deposition process using arc ion plating (AIP), improves adhesion between the coating layer and the base material, enables lamination of dense coating layers, and does not change the performance of the base material. The manufacturing method for a zirconium alloy cladding tube according to one embodiment includes a cladding tube preparation step for preparing a cladding tube made of a zirconium alloy material, a target preparation step, a vacuum heating step, an etching step, and a coating step, and controls changes in the microstructure to prevent recrystallization of the zirconium alloy on the surface of the cladding tube by controlling target conditions, preheating conditions, current conditions, and voltage conditions.

Description

[Technical field]

[0001] A method for manufacturing a zirconium alloy cladding tube is provided. [Background technology]

[0002] Accident Tolerant Fuel (ATF) cladding has been developed to prevent hydrogen explosions by reducing the amount of hydrogen generated in high-temperature steam environments in the event of a nuclear power plant accident. ATF cladding must satisfy various performance requirements in extreme environments, such as corrosion resistance, creep resistance, stability under irradiation deformation, and storage and disposal requirements, which are held by existing cladding, and must be developed with a particular focus on improving oxidation resistance in the event of an accident. However, considering economic efficiency and early commercialization, accident tolerant cladding is being developed worldwide by coating the surface of existing zirconium (Zr) alloy cladding with an oxidation-resistant material.

[0003] To this end, the Korea Atomic Energy Research Institute is researching a method of surface treatment using a 3D printing process on the surface of existing Zr alloy cladding tubes, and a coating method using arc ion plating (AIP) technology. In particular, the AIP method has been selected as a method of improving oxidation resistance by coating Cr or CrAl alloys without damaging the base material of commercial zirconium alloy cladding tubes, and development of the commercial technology is underway.

[0004] However, unlike the advantage of the AIP process of laminating a coating layer onto a zirconium alloy cladding tube, which does not cause any changes to the base material, a problem has emerged in which the microstructure of the zirconium alloy cladding tube changes due to the heat generated during the process.When the microstructure of the zirconium alloy cladding tube changes due to the heat generated during the process, physical properties such as mechanical strength decrease, which poses problems to the structural function of the nuclear fuel cladding tube.

[0005] As a related prior art document, Korean Patent No. 2,161,584 discloses "Metal coating film having excellent high temperature oxidation resistance and corrosion resistance and manufacturing method thereof." [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Korean Patent No. 2,161,584 Summary of the Invention [Problem to be solved by the invention]

[0007] One embodiment provides a method for manufacturing a zirconium alloy cladding tube that suppresses changes in the microstructure of a zirconium alloy base material due to process heat generated during a metal coating film deposition process using arc ion plating (AIP), improves adhesion between the coating layer and the base material, enables lamination of a dense coating layer, and does not change the performance of the base material.

[0008] In addition to the above objects, embodiments of the present invention can be used to achieve other objects not specifically mentioned. [Means for solving the problem]

[0009] A method for manufacturing a zirconium alloy cladding tube according to an embodiment includes a cladding tube preparation step of preparing a cladding tube made of a zirconium alloy material; a target preparation step of preparing a target under preset target conditions, including a coating material to be coated on the surface of the cladding tube; a vacuum heating step of arranging the cladding tube and the target in a chamber and vacuum heating under preset preheating conditions for an initial vacuum; a particle evaporation step of supplying a current under preset current conditions to the surface of the target to generate an arc and evaporate particles of the coating material; and a coating step of supplying a bias voltage under preset voltage conditions to uniformly coat the ionized coating material on the surface of the cladding tube, and adjusting the target conditions, preheating conditions, current conditions, and voltage conditions to adjust a change in microstructure to prevent recrystallization of the zirconium alloy on the surface of the cladding tube. Effect of the Invention

[0010] According to one embodiment, when a zirconium alloy cladding tube is manufactured by applying a coating technique using an arc ion plating technique of a zirconium alloy, the adhesion between the coating layer and the base material can be improved, a dense and high-quality coating layer can be laminated, and the oxidation resistance can be improved, thereby preventing the microstructure of the zirconium alloy cladding tube from being changed by the process heat. [Brief description of the drawings]

[0011] [Figure 1] 1 is a diagram illustrating a process for manufacturing a zirconium alloy cladding tube using target setting conditions according to an embodiment; [Diagram 2] FIG. 4 is a diagram illustrating a process for manufacturing a zirconium alloy cladding tube using target setting conditions according to a comparative example. [Diagram 3] 1 is a diagram illustrating a process for manufacturing a zirconium alloy cladding tube using target setting conditions according to an embodiment; [Figure 4] FIG. 11 is a diagram comparing changes in the microstructure of cladding tubes manufactured using the target setting conditions according to the first experimental example. [Diagram 5] FIG. 11 is a diagram comparing changes in the microstructure of cladding tubes manufactured using the target setting conditions according to the second experimental example. [Figure 6] FIG. 13 is a diagram showing the change in microstructure of a cladding tube manufactured using the target setting conditions according to the third experimental example. [Figure 7] FIG. 13 is a diagram showing the change in microstructure of a cladding tube manufactured using the target setting conditions according to the fourth experimental example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] With reference to the accompanying drawings, the embodiments of the present invention will be described in detail so that those skilled in the art to which the present invention pertains can easily carry out the present invention. The present invention can be realized in various different forms and is not limited to the embodiments described herein. In the drawings, parts that are not necessary for the explanation of the present invention are omitted in order to clearly explain the present invention, and the same reference numerals are used throughout the specification for the same or similar components. In addition, in the case of well-known technology, detailed explanations thereof are omitted.

[0013] Throughout the specification, when a part "comprises" a certain element, this means that it can further include other elements, not excluding other elements, unless specifically stated to the contrary.

[0014] Hereinafter, the method for manufacturing a zirconium alloy cladding tube will be described in detail with reference to the drawings.

[0015] FIG. 1 is a diagram showing a process of manufacturing a zirconium alloy cladding tube using target setting conditions according to an embodiment, and FIG. 2 is a diagram showing a process of manufacturing a zirconium alloy cladding tube using target setting conditions according to a comparative example. A method of manufacturing a zirconium alloy cladding tube according to an embodiment will be described with reference to FIGS. 1 and 2. The method of manufacturing a zirconium alloy cladding tube according to an embodiment includes a cladding tube preparation step, a target preparation step, a vacuum heating step, an etching (cleaning) step, a particle evaporation step, and a coating step, and by adjusting preset target conditions, preheating conditions, current conditions, and voltage conditions, it is possible to easily adjust the change in microstructure to prevent the occurrence of recrystallization of the zirconium alloy on the surface of the cladding tube 20.

[0016] The cladding preparation stage is a stage of preparing a cladding tube 20 made of a zirconium alloy material. Here, the cladding tube 20 is referred to interchangeably as a zirconium alloy cladding tube or an accident tolerant nuclear fuel cladding tube.

[0017] The target preparation step is a step of preparing the target 10 under preset target conditions, including a coating material to be coated on the surface of the cladding tube 20. Here, the coating material may include an oxidation-resistant material. The oxidation-resistant material may include one or more of Cr and Cr alloys. The size of the target 10 may be set to 3 inches.

[0018] The vacuum heating step is a step of vacuum heating under pre-heating conditions set in advance for initial vacuum after placing the cladding tube 20 and the target 10 in the chamber 100. Here, the temperature to which the pre-heating is performed under the pre-heating conditions set in advance can be set to 350° C. or less.

[0019] In the etching (cleaning) step, a preset current and bias voltage are supplied to the surface of the target 10 to generate an arc, evaporating particles of the coating material and removing foreign matter from the surface. In the etching step, the current supplied to the target 10 is 80A or less, the bias voltage is 200V to 600V, and the time can be set within 20 minutes, thereby minimizing changes to the microstructure of the target 10.

[0020] The particle evaporation stage is a stage in which a current is supplied to the surface of the target 10 under preset current conditions to generate an arc and evaporate particles of the coating material. In the particle evaporation stage, the coating material particles evaporate, and a cleaning function can also be performed to remove foreign matter from the surface of the cladding tube. Here, under the preset current conditions, the current supplied to the target 10 can be set to 80 A or less, the bias voltage can be set to a range of 200 to 600 V, and the time can be set to within 20 minutes. Even if the bias voltage is high in the particle evaporation stage, no change (recrystallization) in the microstructure of the cladding tube 20 made of a zirconium alloy occurs within 20 minutes.

[0021] The coating step is a step of uniformly coating the surface of the cladding tube 20 with the ionized coating material by supplying a bias voltage under preset voltage conditions to increase the deposition rate of the evaporated particles. Here, the current supplied to the target 10 under the preset voltage conditions is 80A or less, and the bias voltage can be set to less than 100V. If the bias voltage is too high, etching may occur and deposition efficiency may decrease. In addition, when performing vacuum heating at a preheating temperature of 350°C or less, it is possible to prevent a decrease in high-temperature oxidation resistance and peeling from the interface of the Cr-Al thin film, which may occur when the bias voltage is less than 100V. In the coating step, the coating time can be 3 hours or more to obtain a 10 micron thick Cr or Cr alloy coating layer. For example, the coating time takes about 10 hours to uniformly coat 10 microns or more of Cr or Cr alloy on a zirconium alloy, and such a long coating time can cause recrystallization of the zirconium alloy base material and reduce changes in the microstructure of the target.

[0022] 1 and 2, examples of changes in the microstructure of a zirconium alloy cladding tube due to the effect of the arc ion plating (AIP) process can be seen. For example, in FIG. 1 and FIG. 2, the recrystallization phenomenon of the cladding tube 20 due to the difference in the current and bias voltage supplied to the 3-inch target can be compared. As in the embodiment of FIG. 1, when the 3-inch target 10 is supplied with a current of 80A and a bias voltage of less than 100V, no change in the microstructure occurs on the surface of the cladding tube 20. Reference numeral 12 denotes an evaporation portion in the 3-inch target 10.

[0023] In contrast, in the comparative example of FIG. 2, when a 3-inch target 10 is used, a current of 90 A is supplied, and a bias voltage of 120 V or more is supplied, a change in the microstructure occurs on the surface of the cladding tube 20.

[0024] 2, when a 3-inch target 10 is used, a current of 90 A, and a bias voltage of 120 V or more are supplied, a change in the microstructure occurs on the surface of the cladding tube 20. Therefore, it is necessary to adjust the size of the target 10 and the current formation area due to the magnetic field to confirm the recrystallization phenomenon due to the change in the microstructure on the surface of the cladding tube 20. Reference numeral 20a denotes a microstructural change area that occurs on the surface of the cladding tube 20.

[0025] FIG. 3 is a schematic diagram showing a process of manufacturing a zirconium alloy cladding tube using target setting conditions according to an embodiment. Referring to FIG. 3, when the current and bias voltage supplied to the target 10 are set to 90A and 120V, respectively, the size of the target 10 is increased. For example, the size of the target can be set to 5 inches, and such a 5-inch target can be rotated. Reference numeral 10a indicates a 5-inch target. And reference numeral 12a indicates a plurality of evaporation portions in the 5-inch target 10a. Referring to FIG. 3, due to the rotation of the target, the arc appears in a donut shape instead of a single point shape.

[0026] For example, when the current and bias voltage supplied to the target 10 are 90 A and 120 V, respectively, the size of the target 10 can be changed from 3 inches to 5 inches, and the current can be controlled by a magnetic field so that the arc rotates without concentrating in one place. Here, a device for rotating the target is provided.

[0027] Zirconium alloys are used with stress relaxation or partial recrystallization heat treatment, depending on the alloy composition. Such heat treatment is to secure properties such as mechanical strength and corrosion resistance in the furnace. Recrystallization of most zirconium alloys begins at temperatures above 450 degrees, but if they are maintained at temperatures above the recrystallization temperature for a long period of time, recrystallization will inevitably occur, which will reduce mechanical strength and change corrosion resistance due to an increase in the size of precipitates. In addition, if recrystallization occurs partially, the cladding tube 20 may be damaged due to the difference between local mechanical deformation in the weak part and the amount of creep and irradiation growth deformation. Therefore, if undesired recrystallization occurs in the cladding tube 20, the performance of the cladding tube 20 will deviate from the intended performance.

[0028] Coating oxidation-resistant materials using arc ion plating is being developed as an accident-resistant nuclear fuel manufacturing technology that prevents hydrogen explosions by coating the surface of existing zirconium alloy cladding tubes with oxidation-resistant materials to a thickness of 50 microns or less, suppressing oxidation under normal conditions and accident environments in nuclear reactors. The advantage of arc ion plating is that it is known and has been applied as a technology for coating high-melting point materials without damaging or changing the base material. However, when coating oxidation-resistant materials (Cr or Cr-Al alloy) on zirconium nuclear fuel cladding tubes, process variables can cause the process heat to reach the zirconium alloy, causing recrystallization.

[0029] In one embodiment, partial recrystallization can be prevented from occurring in the longitudinal direction of the cladding tube 20. In a typical process, the application of current and bias voltage and the change in the geometric shape that occurs during consumption of the coating target cause radiant heat generated during surface melting of the target to be transferred to the zirconium alloy, causing excessive temperature to build up.

[0030] In one embodiment, the problem of microstructural change due to recrystallization of the zirconium alloy can be solved by limiting the preheating conditions for the initial vacuum, the applied current and bias voltage conditions during coating, and the radiant heat control conditions by controlling the size of the target and the consumption area.

[0031] In one embodiment, the change in microstructure caused by process heat generated when coating the cladding tube 20 with an oxidation-resistant material (Cr or Cr alloy, where Cr alloy includes Cr-based alloys including Cr-Al) in an arc ion plating process can be suppressed.

[0032] The heat generated during the arc ion plating vacuum deposition process and the way it can be transferred to the cladding tube 20 as the coating target and the conditions for recrystallization will now be described.

[0033] 1) Preheating conditions when evacuating the chamber 100 in the vacuum heating step: In order to realize a high vacuum state in the chamber 100, a heater is used for heating, which activates the gas molecules attached inside and facilitates discharge to the vacuum pump. Here, the maximum temperature of the heater can be set to 350° C. or less. If the maximum temperature of the heater is set to 350° C. or less, it is lower than the recrystallization temperature of the zirconium alloy, which is 450° C. However, the actual temperature of the zirconium alloy may increase due to the inflow of additional heat caused by the application of current and bias voltage to the target 10 in the subsequent process, which may cause recrystallization. This preheating process is different from the deposition process performed later, and the temperature in the deposition process is less than about 200° C. Also, the preheating process is performed for about 20 to 30 minutes.

[0034] 2) Conditions of current supplied to the target 10 in the particle evaporation stage: An arc can be generated on the surface of the target 10 to evaporate the target material. The arc heat exceeds 1,900 degrees in order to sufficiently ionize Cr and Cr alloys. The radiant heat of the arc generated at this time can cause recrystallization of the zirconium alloy. Therefore, the current for arc generation can be set to be supplied at 80 A or less, which is the minimum condition for melting the target 10.

[0035] 3) Bias voltage conditions between the target 10 and the cladding tube 20 during the coating stage: The surface of the target 10 evaporates in an ionized state due to the arc, and the evaporated particles fly out from the target 10. If a bias voltage is applied at this time, the particle speed increases and the size of the evaporated particles also increases. The increased particle speed and size increases the possibility of recrystallization as the heat held by the particles is transferred to the cladding tube 20, which is the object of coating. Therefore, the maximum bias voltage for increasing the deposition speed can be set to less than 100V.

[0036] Additionally, as the target 10 is consumed, the surface changes to a concave lens shape. If the surface of the target 10 changes to a specific shape of curvature, the radiant heat from the arc current is likely to concentrate on a specific region of the cladding tube 20, increasing the possibility of recrystallization occurring. Therefore, by controlling the concave lens shape generated when the target 10 surface is lost, it is possible to prevent recrystallization from occurring due to the radiant heat concentrating on a specific region of the target.

[0037] In arc ion plating for coating the accident-resistant nuclear fuel cladding tube 20, a target 10 and a test piece are placed in a chamber 100, and then a high vacuum atmosphere is created by heating. Then, a current is instantly applied to the surface of the material (target) to be deposited, generating an arc and evaporating particles. Next, a bias voltage is applied to increase the deposition speed of the evaporated particles, allowing the ionized target material to be coated uniformly on the test piece.

[0038] However, in the process of coating the cladding tube 20 with an oxidation-resistant material (Cr, Cr alloy), a phenomenon in which the cladding tube 20 is entirely or partially recrystallized may occur unintentionally.

[0039] In one embodiment, in order to solve the recrystallization problem of the zirconium alloy, the conditions of the vacuum heating condition in the chamber 100, the current and bias voltage supplied to the target 10 among the parameters of the arc ion plating process can be optimized. Also, in order to prevent the accumulation of radiant heat due to the formation of a concave lens when the target 10 is consumed, the size of the target 10 can be significantly changed, and the phenomenon of the arc current concentrating in one area due to the magnetic field can be eliminated.

[0040] For example, during the process, the heating temperature of the chamber 100 in a vacuum state can be set to be maintained at 350° C. or less, the current supplied to the target 10 can be set to be maintained at 80 A or less, and the bias voltage can be set to be maintained at less than 100 V. Here, if one or more of the set conditions of the heating temperature, the target current, and the bias voltage exceed the set limit values, a recrystallization problem of the zirconium alloy may occur.

[0041] The arc ion plating method according to one embodiment can be considered a type of physical vapor deposition method, and requires optimization of deposition conditions to perform atom-by-atom deposition by supplying a current and a bias voltage to the target 10.

[0042] Here, the current supplied to the target 10 is 80 A or less, preferably 70 A or more and 80 A or less, and the bias voltage can be set to less than 100 V, preferably 70 V or more and less than 100 V. If the current value supplied to the target 10 is less than 70 A, the deposition rate may decrease. If the current value supplied to the target 10 is more than 80 A, the size and number of droplets generated in the coating thin film may increase.

[0043] On the other hand, if the bias voltage supplied to the target 10 is less than 70 V, the high temperature oxidation resistance decreases and the coating thin film may peel off from the interface. If the bias voltage supplied to the target 10 is more than 100 V, the deposition rate may decrease significantly.

[0044] During deposition, the larger the size of the evaporated material, the slower the acceleration speed, and therefore the material may not reach the target due to collision with gas molecules. For this reason, by increasing the operating pressure during deposition, the probability of ions and droplets generated on the target 10 colliding with gas molecules can be reduced. The operating pressure during deposition can be set to 5mTorr to 30mTorr. If the operating pressure during deposition is less than 5mTorr, surface roughness and droplets may increase.

[0045] FIG. 4 is a diagram comparing the change in the microstructure of the cladding tube 20 manufactured using the target setting conditions according to the first experimental example. FIG. 4 is a 3-inch target. Referring to FIG. 4, the current supplied to the target 10 is maintained at 80A or less, and the bias voltage supplied to the target 10 is set to 70V, and the change in the microstructure of the cladding tube 20 is compared. As shown in the left diagram of FIG. 4, when the current supplied to the target 10 is maintained at 70A and the bias voltage supplied to the target 10 is set to 70V, there is no change in the microstructure of the cladding tube 20. In contrast, as shown in the right diagram of FIG. 4, when the current supplied to the target 10 is maintained at 90A and the bias voltage supplied to the target 10 is set to 70V, recrystallization occurs due to the change in the microstructure of the cladding tube 20.

[0046] FIG. 5 is a diagram comparing the change in the microstructure of the cladding tube 20 manufactured using the target setting conditions according to the second experimental example. FIG. 5 is a 3-inch target. Referring to FIG. 5, the bias voltage supplied to the target 10 is set to less than 100V and more than 100V, and the current supplied to the target 10 is set to 70A, and the change in the microstructure of the cladding tube 20 is compared. As shown in the left diagram of FIG. 5, when the current supplied to the target 10 is maintained at 70A and the bias voltage supplied to the target 10 is set to 90V, there is no change in the microstructure of the cladding tube 20. In contrast, as shown in the right diagram of FIG. 5, when the current supplied to the target 10 is maintained at 70A and the bias voltage supplied to the target 10 is set to 120V, recrystallization occurs in the change in the microstructure of the cladding tube 20.

[0047] 6 is a diagram showing the change in the microstructure of the cladding tube 20 manufactured using the target setting conditions according to the third experimental example. Referring to FIG. 6, the current and bias voltage supplied to the target 10 are set to 90A and 120V, respectively, and the size of the target 10 can be set to 3 inches. When the current and bias voltage supplied to the target 10 are set to 90A and 120V, respectively, the arc is concentrated at one point on the target 10, and recrystallization occurs due to the change in the microstructure of the cladding tube 20.

[0048] 7 is a diagram showing the change in the microstructure of the cladding tube 20 manufactured using the target setting conditions according to the fourth experimental example. Referring to FIG. 7, the current and bias voltage supplied to the target 10a are set to 90A and 120V, respectively, and the size of the target 10a can be changed to 5 inches, which is larger than 3 inches. And, when the current and bias voltage supplied to the 5-inch target 10a are 90A and 120V, respectively, there is no change in the microstructure of the cladding tube 20. This is because the current is controlled by the magnetic field so that the arc rotates without concentrating in one place in the 5-inch target 10a.

[0049] Only when the current and bias voltage supplied to the target are low does recrystallization occur. The larger the target, the better the process efficiency, but when the current and bias voltage are high, rotation control can be difficult. When the current supplied to the target is 80A or less and the bias voltage is less than 100V, there is no change in the microstructure if the target size is 3 inches or more. However, when the target size is less than 3 inches, for example, 2 inches, there is a change in the microstructure and the process efficiency is low. The target size may be 10 inches or less. When the target size is larger than 10 inches, manufacturing is difficult and the target yield may decrease. For example, the target may have a size of 3 inches to 5 inches. The efficiency of a 5-inch target is higher than that of a 3-inch target. When the current supplied to the target exceeds 80A or the bias voltage is 100V or more, there is no change in the microstructure if the target size is 5 inches or more and the current is controlled by a magnetic field to rotate in an arc. Furthermore, when the current exceeds 80A or the bias voltage is 100V or more, the target size is 4 inches, and there is an arc rotating magnetic field, there is no change in the microstructure. Thus, when the current exceeds 80A or the bias voltage is 100V or more, the target size is 4 inches or more, and there is an arc rotating magnetic field, there is no change in the microstructure. In this case, too, it is preferable that the target size is 10 inches or less, taking into consideration manufacturability and target yield.

[0050] In the oxidation-resistant material deposition process of the cladding tube 20 applied to the accident-resistant nuclear fuel using the arc ion plating method, if the microstructure of the cladding tube 20 changes, it affects the mechanical properties and corrosion properties, making it difficult to achieve the performance target of the cladding tube 20 used for the accident-resistant nuclear fuel. In one embodiment, in a coating technology using the arc ion plating technology of a zirconium alloy, the adhesive strength between the coating layer and the base material can be improved, and a coating technology can be realized that allows stacking of dense, high-quality coating layers and does not change the performance of the base material. Accident-resistant nuclear fuel is required to be applied to all operating nuclear power plants in the future, according to the current EU taxonomy standard that accident-resistant nuclear fuel must be applied to operating nuclear power plants after 2025. Therefore, the application of accident-resistant nuclear fuel cladding tubes to operating nuclear power plants is inevitable, and one embodiment is a core technology related to the manufacture of accident-resistant nuclear fuel cladding tubes, and it is expected that not only the safety of operating nuclear power plants will be improved, but also the economic effect of possessing the technology will be great.

[0051] Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concept of the present invention defined in the following claims also fall within the scope of the present invention.

Claims

1. a cladding tube preparation step of preparing a cladding tube made of a zirconium alloy material; a target preparation step of preparing a target under preset target conditions, the target including a coating material to be coated on a surface of the cladding tube; a vacuum heating step of placing the cladding tube and the target in a chamber and then vacuum heating the chamber under a preheating condition preset for an initial vacuum; an etching step of supplying a preset current and bias voltage to the surface of the target to generate an arc and evaporate particles of the coating material to remove foreign matter on the surface; a particle evaporation step of supplying a current to the surface of the target under a preset current condition to generate an arc and evaporate particles of the coating material; a coating step of uniformly coating the surface of the cladding tube with an ionized coating material by supplying a bias voltage under a preset voltage condition; Including, A method for manufacturing a zirconium alloy cladding tube, comprising adjusting the target conditions, the preheating conditions, the current conditions, and the voltage conditions to adjust a change in microstructure so as to prevent recrystallization of the zirconium alloy on the surface of the cladding tube.

2. The method of claim 1 , wherein the coating material comprises an oxidation resistant material.

3. The method of claim 2 , wherein the oxidation resistant material comprises one or more of Cr, Cr alloys.

4. The method for manufacturing a zirconium alloy cladding tube according to claim 1 , wherein the preheating temperature is set to 350° C. or less.

5. 2. The method of claim 1, wherein in the etching step, a current supplied to the target is 80 A or less, a bias voltage is 200 V to 600 V, and a time is set to 20 minutes or less.

6. 2. The method for manufacturing a zirconium alloy cladding tube according to claim 1, wherein the current supplied to the target in the particle evaporation step is set to 80 A or less.

7. 2. The method for manufacturing a zirconium alloy cladding tube according to claim 1, wherein a bias voltage supplied to the target during the coating step is set to less than 100V.

8. The method for manufacturing a zirconium alloy cladding tube according to claim 1 , wherein the size of the target is set to be 3 inches or more and 10 inches or less.

9. 2. The method of claim 1, wherein the target is rotated and the size of the target is set to 4 inches or more and 10 inches or less when the current supplied to the target in the particle evaporation step exceeds 80 A or the bias voltage in the coating step is 100 V or more.

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