A novel method for welding zirconium alloy fuel rods

Abstract

The application provides a novel zirconium alloy fuel rod welding method, which comprises the following steps: ring seam welding is performed on a lower end plug, a welding chamber vacuum degree setting value is less than or equal to 6.5 Pa, a sub-chamber vacuum degree value is less than or equal to 6.5*10 2 Pa, and a rotating speed is set to 4 s / r; ring seam welding is performed on an upper end plug, a welding chamber vacuum degree setting value is less than or equal to 6.5 Pa, and a rotating speed is set to 4 s / r. The application accelerates the rotating speed of a workpiece during welding, re-matches welding process parameters such as welding current, welding time, post-weld cooling time, welding chamber vacuum degree, sub-chamber vacuum degree, protection gas filling pressure and electrode gap under high rotating speed, and improves production efficiency. The application reduces the problem of heavy oxidation color on a welding seam, improves the generation of a welding seam porosity defect, and improves the welding quality of the welding seam.

Description

Technical Field

[0001] This invention relates to the field of nuclear fuel element manufacturing technology for nuclear power plants, and in particular to a novel method for welding zirconium alloy fuel rods. Background Technology

[0002] Fuel rods are crucial units in nuclear power plant fuel assemblies, serving as the energy source for the reactor. The materials used and the manufacturing quality of the fuel rods play a critical role in the safe operation of the fuel assembly within the reactor. To achieve self-sufficiency in fuel assembly materials and domestic manufacturing, a novel zirconium alloy has been independently developed. Previous experimental studies on TIG welding of the end plugs of these novel zirconium alloy fuel rods employed a slow-speed welding process, resulting in low production efficiency and significant oxide discoloration around the weld. Therefore, developing a novel TIG circumferential welding technology for the end plugs of zirconium alloy fuel rods is of paramount importance. Summary of the Invention

[0003] The purpose of this invention is to provide a novel welding method for zirconium alloy fuel rods, which optimizes welding parameters, reduces oxidation discoloration around the weld, and solves the problems of weld porosity defects and low production efficiency in novel zirconium alloy fuel rods.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] A novel method for welding zirconium alloy fuel rods includes the following steps:

[0006] Step 1: Perform circumferential welding on the lower end plug. The vacuum level in the welding chamber should be ≤6.5 Pa, and the vacuum level in the auxiliary chamber should be ≤6.5 × 10⁻⁶ Pa. 2 Pa, the rotation speed is set to 4 s / r;

[0007] Step 2: Perform circumferential welding on the upper plug, with the vacuum level of the welding chamber set to ≤6.5Pa and the rotation speed set to 4s / r.

[0008] Step 1 specifically includes:

[0009] Step 1.1: The lower end of the fuel rod enters the welding chamber of the lower end plug TIG ring welding machine through the fuel rod axial transmission mechanism until the lower end plug is in close contact with the lower end plug top tooling in the welding chamber;

[0010] Step 1.2: After the lower end plug is tightly attached to the lower end plug top tooling inside the welding chamber, the casing tube side clamp is used to clamp the casing tube.

[0011] Step 1.3: Evacuate the air in the welding chamber using a mechanical pump in the welding chamber, and evacuate the air in the cladding tube from the upper end of the cladding tube using a mechanical pump in the auxiliary chamber.

[0012] Step 1.4: The vacuum level in the welding chamber reaches the set value, and the vacuum level in the auxiliary chamber reaches the set value;

[0013] Step 1.5: After the vacuum value is reached, open the solenoid valve and fill the welding chamber with helium gas at a pressure of at least 0.14 MPa;

[0014] Step 1.6: Maintain a helium pressure of not less than 0.14 MPa inside the welding chamber;

[0015] Step 1.7: Adjust the electrode spacing before welding. Rotate the fuel rod along the axis at a speed of 4 seconds per revolution. After the speed stabilizes, start welding according to the selected welding parameters. The welding is automatically controlled. After the arc is extinguished, the fuel rod stops rotating.

[0016] Step 1.8: During the cooling process, the helium pressure in the welding chamber is maintained at no less than 0.14 MPa, and the workpiece is cooled through the top tooling and chuck.

[0017] Step 1.9: After the cooling time is reached, close the helium inlet solenoid valve;

[0018] Step 1.10: Open the exhaust solenoid valve to release the helium gas in the welding chamber, thus connecting the welding chamber to the atmosphere;

[0019] Step 1.11: The auxiliary chamber exits the upper end of the fuel rod along the axial direction of the fuel rod;

[0020] Step 1.12: The fuel rod moves axially towards the upper end plug until the lower end plug is completely removed from the welding chamber.

[0021] Step 2 specifically includes:

[0022] Step 2.1: The upper end of the fuel rod enters the welding chamber of the upper plug TIG ring welding machine through the fuel rod axial transmission mechanism until the upper plug is in close contact with the upper plug top tooling in the welding chamber;

[0023] Step 2.2: After the upper plug is tightly attached to the upper plug top tooling inside the welding chamber, the casing tube side clamp clamps the casing tube.

[0024] Step 2.3: Evacuate the air inside the welding chamber using a mechanical pump;

[0025] Step 2.4: The vacuum level in the welding chamber reaches the set value;

[0026] Step 2.5: After the vacuum value is reached, open the solenoid valve and fill the welding chamber with helium gas at a pressure of at least 0.14 MPa;

[0027] Step 2.6: Maintain a helium pressure of not less than 0.14 MPa inside the welding chamber;

[0028] Step 2.7: Adjust the electrode spacing before welding. Rotate the fuel rod along the axis at a speed of 4 seconds per revolution. After the speed stabilizes, start welding according to the selected welding parameters. The welding is controlled by an automatic program. After the arc is extinguished, the fuel rod stops rotating.

[0029] Step 2.8: During the cooling process, the helium pressure in the welding chamber is maintained at no less than 0.14 MPa, and the workpiece is cooled through the top tooling and chuck.

[0030] Step 2.9: After the cooling time is reached, close the helium inlet solenoid valve;

[0031] Step 2.10: Open the exhaust solenoid valve to release the helium gas in the welding chamber, thus connecting the welding chamber to the atmosphere;

[0032] Step 2.11: The fuel rod moves axially toward the lower end plug until the upper end plug is completely removed from the welding chamber.

[0033] In steps 1.5 and 2.5, helium with a purity of ≥99.9995% is used as the protective gas, and the arc-starting helium pressure is ≥0.14MPa.

[0034] In steps 1.7 and 2.7, pulsed current welding is used, with the peak current set at 28A to 32A to ensure that the weld penetration depth meets the requirements; the base current is set at 18A to reduce the difference between the base current and the peak current, which is conducive to the escape of pores during welding and avoids the presence of pores in the weld.

[0035] In steps 1.7 and 2.7, the electrode spacing is determined to be 0.4mm ± 0.1mm to avoid the electrode energy being difficult to effectively transfer to the workpiece due to the electrode spacing being too far, and at the same time to avoid the weld seam sticking to tungsten due to the electrode spacing being too close, so as to obtain a weld seam with a moderate weld seam width.

[0036] In steps 1.7 and 2.7, the welding time is set to 6 seconds, and the welding is performed in 1.5 turns.

[0037] In steps 1.8 and 2.8, the post-weld cooling time shall not be less than 10 seconds.

[0038] The novel zirconium alloy fuel rod welding method further includes step 3: inspecting the circumferential weld after welding.

[0039] Furthermore, corrosion tests were conducted on the upper and lower plug ring welds. The corrosion tests were carried out for 72 to 80 hours in water at 360℃±6℃ and under a pressure of 18.7MPa±1.4MPa. After the test, the samples were compared with the appearance standard. The samples were considered qualified if there were no traces of white or brown corrosion products exceeding the standard on them.

[0040] Compared with the prior art, the novel zirconium alloy fuel rod welding method provided by the present invention has the following beneficial effects:

[0041] This invention accelerates the workpiece rotation speed during welding and re-matches welding process parameters such as welding current, welding time, post-weld cooling time, welding chamber vacuum, auxiliary chamber vacuum, shielding gas filling pressure, and electrode spacing at high speeds, thereby improving production efficiency. This invention also alleviates the problem of heavy oxide discoloration around the weld, improves the formation of weld porosity defects, and enhances the weld quality.

[0042] Welding tests and production practice show that, with appropriate welding process parameters and increased welding speed, the oxidation color around the weld can be reduced, and the formation of weld porosity can be effectively avoided. The appearance and dimensions of the samples after welding are qualified, and the physical and chemical properties and dimensions of the welded fuel rod ring weld are qualified. Attached Figure Description

[0043] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the technical description will be briefly introduced below.

[0044] Figure 1 This is a schematic diagram of the structure of a fuel rod in the prior art.

[0045] Explanation of reference numerals in the attached figures:

[0046] 1-Upper plug; 2-Upper ring weld; 3-Spring; 4-Core block; 5-Shell tube; 6-Lower ring weld; 7-Lower plug. Detailed Implementation

[0047] The following detailed description provides further details on specific implementation methods.

[0048] To facilitate understanding, a brief introduction to existing fuel rods is provided first. A fuel rod consists of an upper plug 1, a lower plug 7, a cladding tube 5, a fuel filler block 4, and a spring 3. The upper plug 1, lower plug 7, and cladding tube 5 are all made of a new zirconium alloy. The upper plug 1 and lower plug 7 are respectively circumferentially welded to both ends of the cladding tube 5. The positions of the upper circumferential weld 2 and the lower circumferential weld 6 are as follows: Figure 1 As shown.

[0049] This invention provides a novel method for welding zirconium alloy fuel rods, comprising the following steps:

[0050] Step 1: Perform circumferential welding on the lower end plug. Step 1 specifically includes:

[0051] Step 1.1 (Lower end of fuel rod enters the welding chamber): The lower end of the fuel rod enters the welding chamber of the lower end plug TIG ring welding machine through the fuel rod axial transmission mechanism until the lower end plug is in close contact with the lower end plug top tooling in the welding chamber.

[0052] Step 1.2 (Fuel Rod Clamping and Weld Chamber Sealing): After the lower end plug is tightly fitted against the lower end plug top tooling inside the weld chamber, the cladding tube side clamp clamps the cladding tube. The lower end plug side top abuts against the end plug, and the cladding tube side clamp clamps the tube, thus fixing the position of the lower end circumferential seam in the weld chamber. When the clamp clamps the cladding tube, the sealing ring seals the tube side, cutting off the communication between the weld chamber and the atmosphere.

[0053] Step 1.3 (Vacuuming of Auxiliary Chamber and Welding Chamber): The air inside the welding chamber is evacuated using a mechanical pump in the welding chamber. The air inside the cladding tube is evacuated from the upper end of the cladding tube using a mechanical pump in the auxiliary chamber.

[0054] Step 1.4 (Vacuum value reached): The vacuum level in the welding chamber reaches the set value (the actual vacuum in the welding chamber is better than the set value), and the vacuum level in the auxiliary chamber reaches the set value (the actual vacuum in the auxiliary chamber is better than the set value).

[0055] Step 1.5 (Helium Filling): After the vacuum value is reached, open the solenoid valve and fill the welding chamber with helium gas at a pressure of at least 0.14 MPa.

[0056] Step 1.6 (Pressure Holding): Maintain a helium pressure of not less than 0.14 MPa in the welding chamber.

[0057] Step 1.7 (Girdle Welding): Adjust the electrode spacing before welding. Rotate the fuel rod along the axis at a speed of 4 seconds per revolution. After the speed stabilizes, start welding according to the selected welding parameters. The welding is controlled by an automatic program. The arc is extinguished after 6 seconds, and the fuel rod stops rotating after the arc is extinguished.

[0058] Step 1.8 (Cooling): During the cooling process, the helium pressure inside the welding chamber shall be maintained at no less than 0.14 MPa. The workpiece shall be cooled through the mandrel and chuck, with a cooling time of no less than 10 seconds.

[0059] Step 1.9 (Close the helium inlet valve): After the cooling time has been reached, close the helium inlet solenoid valve.

[0060] Step 1.10 (Exhaust): Open the exhaust solenoid valve to remove helium from the welding chamber, thus connecting the welding chamber to the atmosphere.

[0061] Step 1.11 (Fuel rod exits the auxiliary chamber): The auxiliary chamber exits the upper end of the fuel rod along the axial direction of the fuel rod.

[0062] Step 1.12 (Fuel rod exits the welding chamber): The fuel rod moves axially towards the upper end plug until the lower end plug is completely exited from the welding chamber.

[0063] Step 2: Perform circumferential welding on the upper plug. Step 2 specifically includes:

[0064] Step 2.1 (Upper end of fuel rod enters the welding chamber): The upper end of the fuel rod enters the welding chamber of the upper plug TIG ring welding machine through the fuel rod axial transmission mechanism until the upper plug is in close contact with the upper plug top tooling inside the welding chamber.

[0065] Step 2.2 (Fuel Rod Clamping and Weld Chamber Sealing): After the upper plug is tightly fitted against the upper plug head fixture inside the weld chamber, the cladding tube side clamp clamps the cladding tube. The upper plug side head presses against the end plug, and the cladding tube side clamp clamps the tube, thus fixing the position of the upper circumferential seam in the weld chamber. When the clamp clamps the cladding tube, the sealing ring seals the tube side, cutting off the connection between the weld chamber and the atmosphere.

[0066] Step 2.3 (Evacuation of the Welding Chamber): The air inside the welding chamber is evacuated using a mechanical pump. A small hole is located in the center of the upper mandrel fixture; the mechanical pump evacuates the fuel rods through this hole and the small hole in the upper plug.

[0067] Step 2.4 (Vacuum value reached): The vacuum level in the welding chamber reaches the set value (the actual vacuum in the welding chamber is better than the set value).

[0068] Step 2.5 (Helium Filling): After the vacuum value is reached, open the solenoid valve and fill the welding chamber with helium gas at a pressure of at least 0.14 MPa.

[0069] Step 2.6 (Pressure Holding): Maintain a helium pressure of not less than 0.14 MPa in the welding chamber.

[0070] Step 2.7 (Girdle Welding): Adjust the electrode spacing before welding. Rotate the fuel rod along the axis at a speed of 4 seconds per revolution. After the speed stabilizes, start welding according to the selected welding parameters. The welding is automatically controlled by the program. The arc is extinguished after 6 seconds. After the arc is extinguished, the fuel rod stops rotating.

[0071] Step 2.8 (Cooling): During the cooling process, the helium pressure inside the welding chamber shall be maintained at no less than 0.14 MPa. The workpiece shall be cooled through the mandrel and chuck, with a cooling time of no less than 10 seconds.

[0072] Step 2.9 (Close the helium inlet valve): After the cooling time is reached, close the helium inlet solenoid valve.

[0073] Step 2.10 (Exhaust): Open the exhaust solenoid valve to remove helium from the welding chamber, thus connecting the welding chamber to the atmosphere.

[0074] Step 2.11 (Fuel rod exits the welding chamber): The fuel rod moves axially towards the lower end plug until the upper end plug is completely exited from the welding chamber.

[0075] This invention optimizes welding parameters, reduces oxide discoloration defects around the weld, solves weld porosity defects, and improves production efficiency, as follows:

[0076] (1) In steps 1.7 and 2.7, when welding at a slow speed, the heat of the weld is easily concentrated. Therefore, the welding speed is increased to 4s / r to speed up the rotation speed to reduce the heat accumulation during welding, reduce the oxidation color on the weld surface, and meet the production efficiency requirements.

[0077] (2) Steps 1.4 and 2.4, welding chamber vacuum: To reduce the oxidation discoloration around the weld and ensure that the white or brown products on the weld surface after corrosion do not exceed the standard, the welding chamber vacuum should be better than 6.5 Pa and the auxiliary chamber vacuum should be better than 6.5 × 10 Pa during the welding of the lower end plug ring of the fuel rod. 2 Pa; the vacuum in the welding chamber should be better than 6.5 Pa when welding the plug ring at the upper end of the fuel rod.

[0078] (3) Steps 1.5 and 2.5, protective gas: high-purity helium (helium purity ≥ 99.9995%) is used as protective gas, and the arc ignition helium pressure ≥ 0.14 MPa;

[0079] (4) Steps 1.7 and 2.7, welding time: The welding time is determined to be 6s, welding 1.5 turns. During the current rise stage, the current is unstable and the weld penetration and width do not meet the requirements. Cover half a turn to ensure that the effective weld penetration, weld width and weld appearance meet the requirements.

[0080] (5) Steps 1.7 and 2.7, welding current: pulsed current welding is adopted, and the peak current is determined to be 28A~32A to ensure that the weld penetration depth meets the requirements. The base current is determined to be 18A to reduce the difference between the base current and the peak current, which is conducive to the escape of pores during welding and avoids the presence of pores in the weld.

[0081] (6) Steps 1.7 and 2.7, electrode spacing: the distance between the electrode and the workpiece. The electrode spacing is determined to be 0.4mm ± 0.1mm to avoid the electrode energy being difficult to effectively transfer to the workpiece due to the electrode spacing being too far, and at the same time to avoid the tungsten sticking to the weld due to the electrode spacing being too close, so as to obtain a weld with a moderate weld width.

[0082] (7) Steps 1.8 and 2.8, cooling time: the cooling time after welding shall not be less than 10s, to ensure that the oxide color of the weld meets the inspection requirements, and at the same time ensure welding efficiency.

[0083] Step 3: Post-weld inspection of the circumferential weld. Inspection items include:

[0084] (1) The circumferential weld can pass freely through the ring gauge. According to the fuel rod drawings, make a ring gauge with an inner diameter of no more than φ9.69mm and a length of no less than 20mm. After the upper or lower end plug is welded, the end plug and the circumferential weld should pass through the ring gauge. The ring gauge is qualified if it can pass through the circumferential weld section completely without jamming.

[0085] (2) The oxidation color of the weld area does not exceed the standard. Compare the upper or lower plug ring weld after welding with the oxidation color standard. If the oxidation color of the ring weld does not exceed the standard, the oxidation color inspection result is qualified.

[0086] (3) The penetration depth of the circumferential weld of the fuel rod shall be ≥ 90% of the minimum theoretical wall thickness of the tube. Specimens shall be taken from the circumferential weld of the upper end plug and the circumferential weld of the lower end plug for metallographic longitudinal section inspection. If the penetration depth of the weld is ≥ 90% of the minimum theoretical wall thickness of the tube (0.53 mm × 90% = 0.477 mm), the specimen is considered qualified. The circumferential weld of the upper end plug or the circumferential weld of the lower end plug shall be radiographed by X-ray, and the weld is considered qualified if there is no incomplete penetration defect.

[0087] (4) After the water corrosion test, there shall be no traces of excessive white or brown corrosion products on the specimen. The circumferential weld of the upper end plug and the circumferential weld of the lower end plug shall be subjected to the corrosion test. The corrosion test shall be carried out in water at 360°C ± 6°C and under a pressure of 18.7 MPa ± 1.4 MPa for (72 - 80) hours. After the test, the specimen shall be compared with the appearance standard sample. If there are no traces of any excessive white or brown corrosion products on the specimen, it is considered qualified.

[0088] (5) During the metallographic inspection of the specimen, there shall be no pores or inclusions larger than 0.07 mm on the tube side of the weld, and no pores or inclusions with a length or diameter larger than 0.25 mm on the end plug side of the weld. If there are no tungsten inclusions or lack of fusion defects, it is considered qualified. During the X-ray radiography inspection of the fuel rod weld, the weld is considered qualified if there are no pores, cracks, tungsten inclusions or lack of fusion areas and other defects.

[0089] (6) After the burst test, the fracture location shall not occur at the weld. Specimens with a welding geometry consistent with the circumferential weld geometry of the fuel rod shall be subjected to the burst test. If the fracture occurs in the cladding tube and does not occur at the weld, it is considered qualified.

[0090] Therefore, the present invention uses TIG welding, determines appropriate welding process parameters, increases the rotation speed during workpiece welding, reduces the oxidation color beside the weld, avoids the generation of weld porosity defects, welds the circumferential weld of the fuel rod end plug with qualified physical and chemical properties and appearance dimensions, and at the same time solves the problem of low production efficiency.

[0091] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed by the present invention shall be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claimed rights.

Claims

1. A novel method for welding zirconium alloy fuel rods, characterized in that, Includes the following steps: Step 1: Perform circumferential welding on the lower end plug. The vacuum level in the welding chamber should be set to ≤6.5 Pa, and the vacuum level in the auxiliary chamber should be set to ≤6.5 × 10⁻⁶ Pa. 2 Pa, the rotation speed is set to 4 s / r; Step 1 specifically includes: Step 1.1: The lower end of the fuel rod enters the welding chamber of the lower end plug TIG ring welding machine through the fuel rod axial transmission mechanism until the lower end plug is in close contact with the lower end plug top tooling in the welding chamber; Step 1.2: After the lower end plug is tightly attached to the lower end plug top tooling inside the welding chamber, the casing tube side clamp is used to clamp the casing tube. Step 1.3: Evacuate the air in the welding chamber using a mechanical pump in the welding chamber, and evacuate the air in the cladding tube from the upper end of the cladding tube using a mechanical pump in the auxiliary chamber. Step 1.4: The vacuum level in the welding chamber reaches the set value, and the vacuum level in the auxiliary chamber reaches the set value; Step 1.5: After the vacuum value is reached, open the solenoid valve and fill the welding chamber with helium gas at a pressure of at least 0.14 MPa; Step 1.6: Maintain a helium pressure of not less than 0.14 MPa inside the welding chamber; Step 1.7: Adjust the electrode spacing before welding. Rotate the fuel rod along the axis at a speed of 4 seconds per revolution. After the speed stabilizes, start welding according to the selected welding parameters. The welding is automatically controlled. After the arc is extinguished, the fuel rod stops rotating. Step 1.8: During the cooling process, the helium pressure in the welding chamber is maintained at no less than 0.14 MPa, and the workpiece is cooled through the top tooling and chuck. Step 1.9: After the cooling time is reached, close the helium inlet solenoid valve; Step 1.10: Open the exhaust solenoid valve to release the helium gas in the welding chamber, thus connecting the welding chamber to the atmosphere; Step 1.11: The auxiliary chamber exits the upper end of the fuel rod along the axial direction of the fuel rod; Step 1.12: The fuel rod moves axially towards the upper end plug until the lower end plug is completely removed from the welding chamber; Step 2: Perform circumferential welding on the upper plug, with the vacuum level of the welding chamber set to ≤6.5Pa and the rotation speed set to 4s / r.

2. The novel zirconium alloy fuel rod welding method according to claim 1, characterized in that, Step 2 specifically includes: Step 2.1: The upper end of the fuel rod enters the welding chamber of the upper plug TIG ring welding machine through the fuel rod axial transmission mechanism until the upper plug is in close contact with the upper plug top tooling in the welding chamber; Step 2.2: After the upper plug is tightly attached to the upper plug top tooling inside the welding chamber, the casing tube side clamp clamps the casing tube. Step 2.3: Evacuate the air inside the welding chamber using a mechanical pump; Step 2.4: The vacuum level in the welding chamber reaches the set value; Step 2.5: After the vacuum value is reached, open the solenoid valve and fill the welding chamber with helium gas at a pressure of at least 0.14 MPa; Step 2.6: Maintain a helium pressure of not less than 0.14 MPa inside the welding chamber; Step 2.7: Adjust the electrode spacing before welding. Rotate the fuel rod along the axis at a speed of 4 seconds per revolution. After the speed stabilizes, start welding according to the selected welding parameters. The welding is controlled by an automatic program. After the arc is extinguished, the fuel rod stops rotating. Step 2.8: During the cooling process, the helium pressure in the welding chamber is maintained at no less than 0.14 MPa, and the workpiece is cooled through the top tooling and chuck. Step 2.9: After the cooling time is reached, close the helium inlet solenoid valve; Step 2.10: Open the exhaust solenoid valve to release the helium gas in the welding chamber, thus opening the welding chamber to the atmosphere; Step 2.11: The fuel rod moves axially toward the lower end plug until the upper end plug is completely removed from the welding chamber.

3. The novel zirconium alloy fuel rod welding method according to claim 1 or 2, characterized in that, In steps 1.5 and 2.5, helium with a purity of ≥99.9995% is used as the protective gas, and the arc-starting helium pressure is ≥0.14MPa.

4. The novel zirconium alloy fuel rod welding method according to claim 1 or 2, characterized in that, In steps 1.7 and 2.7, pulsed current welding is used, with the peak current set at 28A~32A to ensure that the weld penetration depth meets the requirements; the base current is set at 18A to reduce the difference between the base current and the peak current, which is conducive to the escape of pores during welding and avoids the presence of pores in the weld.

5. The novel zirconium alloy fuel rod welding method according to claim 1 or 2, characterized in that, In steps 1.7 and 2.7, the electrode spacing is determined to be 0.4mm ± 0.1mm to avoid the electrode energy being difficult to effectively transfer to the workpiece due to the electrode spacing being too far, and at the same time to avoid the weld seam sticking to tungsten due to the electrode spacing being too close, so as to obtain a weld seam with a moderate weld seam width.

6. The novel zirconium alloy fuel rod welding method according to claim 1 or 2, characterized in that, In steps 1.7 and 2.7, the welding time is set to 6 seconds, and the welding is performed in 1.5 turns.

7. The novel zirconium alloy fuel rod welding method according to claim 1 or 2, characterized in that, In steps 1.8 and 2.8, the post-weld cooling time shall not be less than 10 seconds.

8. The novel zirconium alloy fuel rod welding method according to claim 1, characterized in that, It also includes step 3: inspecting the circumferential weld after welding.

9. The novel zirconium alloy fuel rod welding method according to claim 8, characterized in that, Corrosion tests were conducted on the upper and lower plug ring welds. The corrosion test was carried out for 72 to 80 hours in water at 360℃±6℃ and pressure at 18.7MPa±1.4MPa. After the test, the samples were compared with the appearance standard. The samples were considered qualified if there were no traces of white or brown corrosion products exceeding the standard on the samples.

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