CN111451633A - Welding and packaging method for molybdenum alloy accident fault-tolerant fuel rod - Google Patents

Welding and packaging method for molybdenum alloy accident fault-tolerant fuel rod Download PDF

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CN111451633A
CN111451633A CN202010272932.7A CN202010272932A CN111451633A CN 111451633 A CN111451633 A CN 111451633A CN 202010272932 A CN202010272932 A CN 202010272932A CN 111451633 A CN111451633 A CN 111451633A
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welding
end plug
cladding tube
molybdenum alloy
fuel rod
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CN111451633B (en
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张林杰
宁杰
张亮亮
解妙霞
尚香涛
孙院军
丁向东
孙军
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Xian Jiaotong University
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Xian Jiaotong University
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/20—Bonding
    • B23K26/21—Bonding by welding
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/12—Working by laser beam, e.g. welding, cutting or boring in a special atmosphere, e.g. in an enclosure
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/12—Working by laser beam, e.g. welding, cutting or boring in a special atmosphere, e.g. in an enclosure
    • B23K26/123—Working by laser beam, e.g. welding, cutting or boring in a special atmosphere, e.g. in an enclosure in an atmosphere of particular gases
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
    • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
    • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
    • B23K26/346—Working by laser beam, e.g. welding, cutting or boring in combination with welding or cutting covered by groups B23K5/00 - B23K25/00, e.g. in combination with resistance welding

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Plasma & Fusion (AREA)
  • Mechanical Engineering (AREA)
  • Laser Beam Processing (AREA)

Abstract

The invention discloses a welding and packaging method of a molybdenum alloy accident fault-tolerant fuel rod. According to the invention, the metal layer is added at the assembly interface of the cladding tube and the solid lower end plug, and the cladding tube and the hollow upper end plug, and the laser welding is carried out in the negative pressure inert gas atmosphere environment, so that the girth welding strength and toughness of the molybdenum alloy fuel rod are improved, and the defect of air holes can be effectively avoided. Because the sealing welding of the hollow upper end plug needs to be carried out under the high pressure of 2-3MPa, the hollow upper end plug and the rod-shaped sealing material are welded by adopting the mode of upset-free rotary friction welding, the welding seam quality and the welding strength of a welding joint are ensured, and the phenomenon that the thin molybdenum alloy cladding tube is squeezed and squashed due to the fact that impact upsetting force is applied when the traditional rotary friction welding is adopted is avoided.

Description

Welding and packaging method for molybdenum alloy accident fault-tolerant fuel rod
Technical Field
The invention relates to the technical field of welding, in particular to a welding and packaging method for a molybdenum alloy accident fault-tolerant fuel rod.
Background
For a long time, the nuclear reactor fuel enclosure assembly has mainly used zirconium alloy material, however in 2011 of japan fukushima nuclear power plant accidents, zirconium alloy reacts with water/water vapor at temperatures of about 1200 ℃ and eventually causes explosions. The explosion of the fukushima nuclear power station unit enables the world nuclear industry and the scientific community to realize the need of developing a novel fuel system, namely accident fault tolerant fuel (ATF for short), which can resist the working condition of a serious accident within a long time, delay the situation deterioration speed, strive for more precious time for people to take emergency measures and greatly reduce the leakage risk of radioactive raw materials. Molybdenum has the advantages of small neutron absorption cross section, good high-temperature strength, good thermal conductivity, good corrosion resistance of a small linear expansion coefficient box and the like, so molybdenum alloy is listed as a main alternative material for ATF cladding in the world nuclear industry.
At present, the traditional welding process of the zirconium alloy fuel rod cladding assembly mainly comprises the following steps: (1) performing girth welding between the lower end plug and the cladding tube in normal pressure atmosphere, (2) performing girth welding between the upper end plug and the cladding tube in normal pressure atmosphere, (3) performing hole plugging of an upper end plug sealing welding point in high-pressure inert gas atmosphere, and realizing helium filling in the sealing box cladding tube; in the welding process, resistance welding, argon arc welding, laser welding and other modes are generally adopted. The welding process described above is not suitable for weld packaging of molybdenum alloy fuel rod cladding assemblies, such as:
because the welded molybdenum alloy has large sizes of the welded seam and the heat affected zone and seriously coarsened crystal grains, the joint has poor strength and toughness under the combined action of intrinsic brittleness of the material and the weakening of a crystal boundary by impurity segregation. The high conductivity of molybdenum deteriorates the weldability of molybdenum and molybdenum alloys by resistance welding, and therefore resistance welding is not suitable for cladding welding of molybdenum alloy fuel rods. The friction stir welding tool is seriously worn, and meanwhile, when the welding is finished and the stirring head is lifted out of a workpiece, a keyhole which is difficult to repair is formed in a welding line, the corrosion resistance of the welding line is reduced, a thin-wall pipe fitting is difficult to clamp, and the like, so the friction stir welding is not suitable for the cladding welding of the molybdenum alloy fuel rod. The brazing seam strength and the heat resistance of the brazing are lower than those of base metal, and the high-temperature service performance of the brazing seam is generally inferior to that of a fusion welding head, so that the brazing is not suitable for cladding welding of molybdenum alloy fuel rods. During fusion welding, after the high-performance molybdenum alloy undergoes the melting-solidification (or recrystallization) process, the toughness advantage disappears, and serious problems of embrittlement and air hole defects occur.
Meanwhile, the upper end plug is also required to be plugged in a high-pressure (2-3MPa) environment, although a high-power-density heat source can be used for welding under the condition of very low heat input to obtain a welding line with a very small size, the molybdenum and molybdenum alloy welding method has great advantages, but the application of the vacuum electron beam welding method is limited due to the high-pressure environment when the upper end plug is used for plugging a hole. When welding is carried out under normal pressure, particularly under negative pressure, because the energy density of a laser welding heat source is high, a metal material is rapidly heated and melted and is accompanied with violent evaporation of the metal, the violent evaporation can generate recoil pressure on the surface of a molten pool, and the liquid level of the molten pool is sunken downwards under the action of the recoil pressure to form a small hole surrounded by liquid metal. The laser beam is reflected for many times in the small hole and converged to the bottom of the small hole, so that the metal at the bottom of the molten pool is evaporated strongly, and the circulation is performed to form a narrow and deep welding line. The recoil pressure is closely related to the environmental pressure, when laser welding is carried out under the high-pressure condition of 2-3MPa, the penetration depth can be greatly reduced, the reduction amplitude is up to more than 80%, meanwhile, the width of a melting zone is greatly increased, and the advantages of small, narrow and deep weld joint size are completely lost, so that the performance of the joint is deteriorated, and therefore, the upper end plug cannot be plugged by using a laser welding method under the high-pressure environment required by nuclear fuel cladding packaging. The rotary friction welding method is characterized in that under the action of pressure, friction heat and plastic deformation are generated on a friction surface and a nearby area of the friction surface by utilizing the relative motion between contact surfaces of a welded workpiece, so that the temperature nearby the contact surfaces is increased to be close to the melting point, the deformation resistance of a material is reduced, the plasticity is improved, an oxide film on the interface is broken, proper flowing and macroscopic plastic deformation are generated along with the material, and welding is realized through atomic diffusion and recrystallization of the interface.
Because molybdenum is listed as a main alternative material of ATF cladding by the world nuclear industry due to the excellent characteristics of molybdenum, a welding and packaging method of the molybdenum alloy accident fault-tolerant fuel rod, which is suitable for molybdenum alloy nuclear fuel cladding packaging and can improve the quality and welding strength of a welding seam, is urgently needed.
Disclosure of Invention
The invention aims to provide a welding and packaging method of a molybdenum alloy accident fault-tolerant fuel rod, which aims to solve the problems in the prior art, so that girth welding at the assembly interface of a cladding tube and a solid lower end plug as well as the assembly interface of the cladding tube and a hollow upper end plug is high in strength and good in toughness, and the defect of air holes can be effectively avoided; the plugging and sealing effect of the upper end plug is good and the joint quality is high at the same time, so that the problems of welding seam quality and welding strength when the molybdenum alloy is used as the cladding of the fuel rod are solved.
In order to achieve the purpose, the invention provides the following scheme:
the invention provides a welding and packaging method of a molybdenum alloy accident fault-tolerant fuel rod, which comprises a solid lower end plug, a cladding tube, a heat insulation block, a nuclear fuel pellet, a spring, a hollow upper end plug and a rod-shaped sealing block, wherein the solid lower end plug, the cladding tube, the hollow upper end plug and the rod-shaped sealing block are all made of molybdenum alloy, and the packaging method comprises the following steps:
a) assembling the solid lower end plug at one end of the cladding tube, adding a metal layer at an assembling interface of the cladding tube and the solid lower end plug, wherein the melting point of the metal layer is lower than those of the cladding tube and the solid lower end plug, welding a circular seam between the solid lower end plug and the cladding tube by adopting laser fusion welding in a negative pressure inert gas atmosphere, melting the solid lower end plug at the assembling interface, a cladding tube base material and the metal layer in the welding process, forming fusion connection between the solid lower end plug and the cladding tube base material at the assembling interface, and forming metallurgical bonding between the metal layer and the assembling interface;
b) sequentially filling the heat insulation block, a plurality of nuclear fuel pellets, the heat insulation block and the spring into the cladding tube, and assembling the hollow upper end plug at the other end of the cladding tube to finish internal assembly;
c) adding the metal layer at an assembly interface of the cladding tube and the hollow upper end plug, wherein the melting point of the metal layer is lower than the melting points of the cladding tube and the hollow upper end plug, welding a circular seam between the hollow upper end plug and the cladding tube by adopting laser fusion welding in a negative pressure inert gas atmosphere environment, melting the hollow upper end plug, a cladding tube base material and the metal layer at the assembly interface in a welding process, forming fusion connection between the hollow upper end plug and the cladding tube base material at the assembly interface, and forming metallurgical bonding between the metal layer and the assembly interface;
d) and welding the hollow upper end plug and the rod-shaped sealing block by adopting an upsetting-free rotary friction welding method under a high-pressure inert gas atmosphere, wherein an instantaneous axial upsetting load with impact is not applied in the rotary friction welding process.
Preferably, the metal layer is a metal layer attached to the assembly interface or a metal layer independently added to the assembly interface, and the material of the metal layer is one or more of Zr, Ti, Ni, Hf and Al.
Preferably, in the step a) and the step c), the method further comprises the steps of preheating the workpiece to 400-450 ℃ before the laser fusion welding, setting the defocusing amount of the laser beam to be-1 mm, setting the welding speed to be 2 m/min-20 m/min, and repeatedly welding the circular seam for multiple times.
Preferably, the laser fusion welding and the upset-free rotary friction welding are both carried out in a high-pressure cabin, and the high-pressure cabin is vacuumized until the pressure in the cabin is less than 10 before the welding starts-9And (4) MPa, then filling inert gas, repeatedly vacuumizing and filling the inert gas in such a way to ensure that the oxygen content of the gas in the hyperbaric chamber is less than or equal to 1.5PPM, the nitrogen content is less than or equal to 50PPM, the total carbon content is less than or equal to 5PPM and the water content is less than or equal to 3PPM, finally filling the inert gas into the hyperbaric chamber, and completing welding in a negative pressure inert gas atmosphere environment or a high pressure inert gas atmosphere environment.
Preferably, when the upset-free rotary friction welding method is adopted, the fuel rod which completes two circular seam welding is clamped on a hydraulic clamp, the clamping contact surface is completely positioned in the hollow upper end plug area, the rod-shaped sealing block is clamped on a rotary chuck connected with a motor, and the hollow upper end plug is aligned with the rod-shaped sealing block; during welding, the motor drives the rotary chuck to rotate so as to drive the rod-shaped sealing block to rotate, and the hydraulic clamp applies constant load, namely welding pressure, in the axial direction through the hydraulic oil cylinder; the rod-shaped sealing block is in contact with the end face of the hollow upper end plug, friction is generated by relative rotation under the welding pressure, welding is completed through heat generated by friction force, the welding pressure is applied in the whole process from the beginning to the end of welding, and the applied welding pressure and the rotating speed of the motor are constant.
Preferably, the welding pressure is 80 +/-10 MPa, the rotating speed is 2000 +/-200 r/min, and the welding time is 3 +/-1 s.
Preferably, the negative pressure value range in the negative pressure inert gas atmosphere environment is as follows: 0.01-0.1MPa, wherein the high pressure value range in the high-pressure inert gas atmosphere environment is as follows: 2 to 3 MPa.
Preferably, after the step d), the method further comprises a step e) of removing flash generated in the upsetting-free rotary friction welding process under the protection of the inert gas under normal pressure.
Preferably, the flash generated in the non-upset rotary friction welding process is removed by adopting a mechanical processing method, and in the removing process, the fuel rod is static, and the processing head rotates to remove the flash.
Preferably, the inert gas is argon or helium.
Compared with the prior art, the invention has the following technical effects:
1. according to the invention, the metal layer is added at the assembly interface of the cladding tube and the solid lower end plug, and the cladding tube and the hollow upper end plug, and the laser fusion welding mode is adopted, so that the solid lower end plug (or the hollow upper end plug) and the cladding tube base metal and the metal layer at the assembly interface are melted in the welding process, the metal layer and the assembly interface position form metallurgical bonding, the toughness and the strength of the welding seam position are improved, and the problems that the toughness advantage disappears and serious embrittlement occurs after the high-performance molybdenum alloy undergoes melting-solidification (or recrystallization) in the traditional fusion welding process are avoided.
2. When the traditional zirconium alloy fuel rod is welded and packaged, girth welding between an upper end plug (or a lower end plug) and a cladding tube is carried out under normal pressure, the laser fusion welding adopted by the invention is carried out under the atmosphere environment of negative pressure inert gas, and gas in a welding molten pool can escape in time under the negative pressure environment, so that the defect of air holes can be effectively avoided, the strength of a welding joint is improved, and meanwhile, the laser fusion welding is carried out under the negative pressure, so that the penetration of the welding joint is favorably increased, a narrow and deep welding joint is formed, and the strength of the joint is further increased.
3. By adopting the mode of upset-free rotary friction welding in a high-pressure inert gas atmosphere environment, the hollow upper end plug and the rod-shaped sealing material are welded, the welding seam quality and the welding strength of a welding joint are ensured, and meanwhile, the phenomenon that the thin molybdenum alloy cladding tube is squeezed and broken due to the fact that the impact upset force is applied when the traditional rotary friction welding is adopted is avoided.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.
FIG. 1 is a block diagram of a molybdenum alloy accident tolerant fuel rod;
FIG. 2 is a schematic view of a laser fusion welded joint of a Zr-added metal layer according to the present invention;
the heat insulation structure comprises a core, a heat insulation block, a core fuel pellet, a spring, a hollow upper end plug and a rod-shaped sealing block, wherein the core comprises 1-a solid lower end plug, 2-a cladding tube, 3-a heat insulation block, 4-a nuclear fuel pellet, 5-a spring, 6-a hollow upper end plug and 7-.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention aims to provide a welding and packaging method of a molybdenum alloy accident fault-tolerant fuel rod, which aims to solve the problems in the prior art, so that girth welding at the assembly interface of a cladding tube and a solid lower end plug as well as the cladding tube and a hollow upper end plug is high in strength and good in toughness, and the defect of air holes can be effectively avoided; the plugging and sealing effect of the upper end plug is good and the joint quality is high at the same time, so that the problems of welding seam quality and welding strength when the molybdenum alloy is used as the cladding of the fuel rod are solved.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
Example one
The embodiment provides a welding and packaging method of a molybdenum alloy accident tolerance fuel rod, which comprises a solid lower end plug 1, a cladding tube 2, a heat insulation block 3, a nuclear fuel pellet 4, a spring 5, a hollow upper end plug 6 and a rod-shaped sealing block 7. The length of the cladding tube 2 is 800mm, the outer diameter is 9.5mm, the wall thickness is 0.5mm, the length of the solid lower end plug 1 is about 10mm, the length of the hollow upper end plug 6 is 35-40mm, and the length of the rod-shaped sealing block 7 is 35-40 mm. Wherein the solid lower end plug 1, the cladding tube 2, the hollow upper end plug 6 and the rod-shaped sealing block 7 are all made of molybdenum alloy.
The welding tool comprises a gas protection chamber, a rotating chuck and a temperature control heating device, and can realize functions of preheating before welding, girth weld joint welding, gas protection and the like in the laser welding process of the molybdenum alloy component.
In the welding process, the cladding tube 2 and the solid lower end plug 1 are firstly polished by sand paper, and then the sample is immersed in acetone for ultrasonic cleaning. A metal layer is added at the assembly interface of the cladding tube 2 and the solid lower end plug 1, the material of the metal layer can be one or more of Zr, Ti, Ni, Hf and Al, the cladding tube 2 and the solid lower end plug 1 are assembled and placed in a high-pressure cabin, and then the assembled cladding tube 2 and the solid lower end plug 1 are clamped by a rotating chuck. Before welding, the high-pressure cabin is vacuumized until the pressure in the cabin is less than 10-9Introducing argon with the purity of 99.999 percent under the MPa, and then vacuumizing until the pressure in the cabin is less than 10-9And (2) MPa, then filling argon with the purity of 99.999 percent, repeatedly vacuumizing and filling the argon in such a way to ensure the purity of the gas in the hyperbaric chamber, so that the oxygen content of the gas in the hyperbaric chamber is less than or equal to 1.5PPM, the nitrogen content is less than or equal to 50PPM, the total carbon content is less than or equal to 5PPM, and the water content is less than or equal to 3PPM, and filling the argon for the last time before welding to ensure that the pressure reaches the pressure (0.01-0.1MPa) of the negative pressure inert gas. The assembled cladding tube 2 and the solid lower end plug 1 were preheated by a heating device before welding at a preheating temperature of 40 deg.fThe preheating before welding can reduce the welding residual stress of the molybdenum alloy laser welding joint at the temperature of between 0 and 450 ℃. In the welding process, the laser head is kept fixed, laser spots are focused on the butt joint area of the cladding tube 2 and the solid lower end plug 1, then the rotating chuck drives the cladding tube 2 and the solid lower end plug 1 to rotate, and the welding of the circular seam of the cladding tube 2 and the solid lower end plug 1 is finished. In the process of carrying out laser fusion welding, the base materials of the solid lower end plug 1 and the cladding tube 2 and the metal layer at the assembly interface are melted, the base materials of the solid lower end plug 1 and the cladding tube 2 form fusion connection at the assembly interface, and the metal layer and the assembly interface form metallurgical bonding.
After the circular seam welding is completed, the heat insulation block 3, the nuclear fuel pellets 4, the heat insulation block 3 and the spring 5 are sequentially placed into the cladding tube 2, then the hollow upper end plug 6 is assembled, a metal layer is added at the assembly interface of the cladding tube 2 and the hollow upper end plug 6, the material of the metal layer is the same as that of the metal layer added at the assembly interface of the cladding tube 2 and the solid lower end plug 1, then the assembled whole is placed into a high-pressure chamber for welding, the welding process is the same as that of the cladding tube 2 and the solid lower end plug 1, and details are not repeated.
After the process is finished, the hollow lower end plug 6 and the rod-shaped sealing material 7 are welded, and the process is carried out in a mode of non-upsetting rotary friction welding in a high-pressure (2-3MPa) environment. The specific operation process is as follows: the fuel rod assembly and the rod-shaped sealing block 7 which are welded in the two circular seam welding processes before are placed into a high-pressure chamber, the rod-shaped sealing block 7 and the hollow upper end plug 6 are respectively assembled on a clamp and centered in the high-pressure chamber, the fuel rod assembly which completes the two circular seam welding processes is clamped by a hydraulic clamp to be immobile, a clamping contact surface is completely positioned in the area of the hollow upper end plug 6, and the rod-shaped sealing block 7 is clamped on a rotary chuck connected with a motor. After clamping is finished, vacuumizing the hyperbaric chamber until the pressure in the hyperbaric chamber is less than 10-9And (3) introducing argon with the purity of 99.999 percent under the MPa, and repeatedly vacuumizing and introducing the argon to ensure the purity of the gas in the hyperbaric chamber, so that the oxygen content of the gas in the hyperbaric chamber is less than or equal to 1.5PPM, the nitrogen content is less than or equal to 50PPM, the total carbon content is less than or equal to 5PPM, and the water content is less than or equal to 3 PPM. Argon is filled for the last time before welding to ensure that the pressure reaches the pressure of the high-pressure packaging gas of the fuel rod: (2-3 MPa). Then, upset-free rotary friction welding is carried out, in the process, a motor drives a rotary chuck to rotate, so that a rod-shaped sealing block 7 is driven to rotate, and a hydraulic clamp applies constant load, namely welding pressure, in the axial direction through a hydraulic oil cylinder; the rod-shaped sealing block 7 is in contact with the end face of the hollow upper end plug 6, friction is generated by relative rotation under welding pressure, welding is completed through heat generated by friction force, and the application of the welding pressure is the whole process from the beginning to the end of the welding. Setting the welding process parameters as follows: the welding pressure is 80 plus or minus 10MPa, the rotating speed of the motor is 2000 plus or minus 200r/min, and the welding time is 3 plus or minus 1 s. In the traditional rotary friction welding, two parts for welding are in contact, the rotary chuck rotates to start the rotary friction welding, when the welding is finished, the hydraulic clamp is pushed by the hydraulic oil cylinder to apply upsetting force, the hydraulic oil cylinder rapidly and non-constantly supplies hydraulic oil, so that the hydraulic clamp is driven to rapidly apply an impulsive axial force forwards, and the welding is finished. In the invention, the upsetting force with impact property applied at the end of welding is eliminated, and the constant welding pressure is applied in the whole welding process. The mode of upset-free rotary friction welding is adopted, so that the phenomenon that the cladding tube is squeezed and broken due to the fact that the wall of the cladding tube 2 is thin due to the fact that an impact upset force needs to be applied in the welding process of the traditional rotary friction welding process is avoided.
After the upsetting-free rotary friction welding process is finished, adjusting the pressure in the high-pressure cabin to the normal pressure level of about 0.101MPa, removing the flash generated in the upsetting-free rotary friction welding process in a mechanical machining mode under the protection of argon, clamping the fuel rods on a clamp in the machining process, rotating the machining head, and cutting off the flash. And after the flash is removed, taking the fuel rod out of the high-pressure cabin, and finishing the whole welding and packaging process.
In the whole welding and packaging process, the argon filled in the high-pressure chamber can also adopt other inert gases such as helium and the like.
Example two
In this embodiment, the solid lower end plug 1, the cladding tube 2, the hollow upper end plug 6 and the rod-shaped sealing block 7 are all made of 0.5 wt% L a2O3The nanoparticles are doped with a strengthening molybdenum alloy, whereinLa2O3The high-melting-point refractory metals such as molybdenum alloy and the like are difficult to process in a smelting mode and are often prepared by adopting a powder metallurgy method, and in the powder metallurgy preparation process, gas in a powder blank cannot completely overflow and is compressed to fill micro-pores in a synthetic material, so that the density of the material is insufficient, therefore L a used in the embodiment is certain in density2O3The nano-particle doped reinforced molybdenum alloy is a high-gas-content material. The welding and packaging process of the fuel rod is the same as that of the first embodiment.
EXAMPLE III
As a preferred embodiment, the metal layer added at the assembly interface of the cladding tube 2 and the solid lower end plug 1, and the cladding tube 2 and the hollow upper end plug 6 is Ti or Zr, the welding parameters of laser fusion welding are set to be 1000-2500W of laser power, 1mm of defocusing amount, 5-12 m/min of welding speed, the welding parameters of upset-free rotary friction welding are set to be 80MPa of welding pressure, 2000r/min of motor rotation speed, 2s of welding time, and the rest operation processes are the same as those of the first embodiment. The welded joint in which Zr element was added is shown in fig. 2.
Example four
In the embodiment, the cladding tube 2 is wrapped with a passive alkali metal molybdenum alloy heat pipe for heat exchange, and the material of the heat pipe is 0.5 wt% L a2O3The nano particles are doped with the reinforced molybdenum alloy, the outer diameter is phi 16mm, the length is 2-8m, and the wall thickness is 1.2 mm.
The whole welding and packaging process is similar to that of the embodiment, and only the welding technological parameters of laser fusion welding are adjusted to be 3000-4000W of laser power, 0mm of defocusing amount and 2-6 m/min of welding speed. The welding technological parameters of the upset-free rotary friction welding are adjusted to 80MPa of welding pressure, 2000r/min of motor speed and 3s of welding time, and the rest technological processes are the same as those of the first embodiment.
The adaptation according to the actual needs is within the scope of the invention.
The principle and the implementation mode of the invention are explained by applying a specific example, and the description of the embodiment is only used for helping to understand the method and the core idea of the invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.

Claims (10)

1. A welding and packaging method for a molybdenum alloy accident fault-tolerant fuel rod is characterized by comprising the following steps: the fuel rod comprises a solid lower end plug, a cladding tube, a heat insulation block, a nuclear fuel pellet, a spring, a hollow upper end plug and a rod-shaped sealing block, wherein the solid lower end plug, the cladding tube, the hollow upper end plug and the rod-shaped sealing block are all made of molybdenum alloy, and the packaging method comprises the following steps:
a) assembling the solid lower end plug at one end of the cladding tube, adding a metal layer at an assembling interface of the cladding tube and the solid lower end plug, wherein the melting point of the metal layer is lower than those of the cladding tube and the solid lower end plug, welding a circular seam between the solid lower end plug and the cladding tube by adopting laser fusion welding in a negative pressure inert gas atmosphere, melting the solid lower end plug at the assembling interface, a cladding tube base material and the metal layer in the welding process, forming fusion connection between the solid lower end plug and the cladding tube base material at the assembling interface, and forming metallurgical bonding between the metal layer and the assembling interface;
b) sequentially filling the heat insulation block, a plurality of nuclear fuel pellets, the heat insulation block and the spring into the cladding tube, and assembling the hollow upper end plug at the other end of the cladding tube to finish internal assembly;
c) adding the metal layer at an assembly interface of the cladding tube and the hollow upper end plug, wherein the melting point of the metal layer is lower than the melting points of the cladding tube and the hollow upper end plug, welding a circular seam between the hollow upper end plug and the cladding tube by adopting laser fusion welding in a negative pressure inert gas atmosphere environment, melting the hollow upper end plug, a cladding tube base material and the metal layer at the assembly interface in a welding process, forming fusion connection between the hollow upper end plug and the cladding tube base material at the assembly interface, and forming metallurgical bonding between the metal layer and the assembly interface;
d) and welding the hollow upper end plug and the rod-shaped sealing block by adopting an upsetting-free rotary friction welding method under a high-pressure inert gas atmosphere, wherein an instantaneous axial upsetting load with impact is not applied in the rotary friction welding process.
2. The welding and packaging method for the molybdenum alloy accident fault-tolerant fuel rod as claimed in claim 1, wherein the welding and packaging method comprises the following steps: the metal layer is attached to the assembly interface or independently added at the assembly interface, and the material of the metal layer is one or more of Zr, Ti, Ni, Hf and Al.
3. The welding and packaging method for the molybdenum alloy accident tolerance fuel rod as claimed in claim 1 or 2, wherein: in the step a) and the step c), the method further comprises the steps of preheating the workpiece to 400-450 ℃ before the laser fusion welding, setting the defocusing amount of a laser beam to be-1 mm, setting the welding speed to be 2 m/min-20 m/min, and repeatedly welding the circular seam for many times.
4. The welding and packaging method for the molybdenum alloy accident tolerance fuel rod as claimed in claim 1 or 2, wherein: the laser fusion welding and the upset-free rotary friction welding are both carried out in the high-pressure cabin, and the high-pressure cabin is vacuumized until the pressure in the cabin is less than 10 before the welding starts-9And (4) MPa, then filling inert gas, repeatedly vacuumizing and filling the inert gas in such a way to ensure that the oxygen content of the gas in the hyperbaric chamber is less than or equal to 1.5PPM, the nitrogen content is less than or equal to 50PPM, the total carbon content is less than or equal to 5PPM and the water content is less than or equal to 3PPM, finally filling the inert gas into the hyperbaric chamber, and completing welding in a negative pressure inert gas atmosphere environment or a high pressure inert gas atmosphere environment.
5. The welding and packaging method for the molybdenum alloy accident fault-tolerant fuel rod as claimed in claim 1, wherein the welding and packaging method comprises the following steps: when the upsetting-free rotary friction welding method is adopted, the fuel rod which completes two circular seam welding is clamped on a hydraulic clamp, the clamping contact surface is completely positioned in the hollow upper end plug area, the rod-shaped sealing block is clamped on a rotary chuck connected with a motor, and the hollow upper end plug is aligned with the rod-shaped sealing block; during welding, the motor drives the rotary chuck to rotate so as to drive the rod-shaped sealing block to rotate, and the hydraulic clamp applies constant load, namely welding pressure, in the axial direction through the hydraulic oil cylinder; the rod-shaped sealing block is in contact with the end face of the hollow upper end plug, friction is generated by relative rotation under the welding pressure, welding is completed through heat generated by friction force, the welding pressure is applied in the whole process from the beginning to the end of welding, and the applied welding pressure and the rotating speed of the motor are constant.
6. The welding and packaging method for the molybdenum alloy accident tolerance fuel rod as claimed in claim 5, wherein the welding and packaging method comprises the following steps: the welding pressure is 80 +/-10 MPa, the rotating speed is 2000 +/-200 r/min, and the welding time is 3 +/-1 s.
7. The welding and packaging method for the molybdenum alloy accident fault-tolerant fuel rod as claimed in claim 1, wherein the welding and packaging method comprises the following steps: the negative pressure value range in the negative pressure inert gas atmosphere environment is as follows: 0.01-0.1MPa, wherein the high pressure value range in the high-pressure inert gas atmosphere environment is as follows: 2 to 3 MPa.
8. The welding and packaging method for the molybdenum alloy accident fault-tolerant fuel rod as claimed in claim 1, wherein the welding and packaging method comprises the following steps: after the step d), the method also comprises a step e) of removing flash generated in the upsetting-free rotary friction welding process under the protection of the inert gas under normal pressure.
9. The method for welding and packaging the molybdenum alloy accident tolerance fuel rod according to claim 8, wherein: and removing the flash generated in the non-upsetting rotary friction welding process by adopting a mechanical processing method, wherein in the removing process, the fuel rod is static, and the processing head rotates to remove the flash.
10. The welding and packaging method for the molybdenum alloy accident tolerance fuel rod as claimed in claim 1 or 8, wherein: the inert gas is argon or helium.
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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4857691A (en) * 1988-06-02 1989-08-15 Westinghouse Electric Corp. Burnable absorber rod end plug welding apparatus and method
EP0345499A2 (en) * 1988-06-06 1989-12-13 Westinghouse Electric Corporation End plug weld for nuclear fuel rod
CN108015445A (en) * 2017-12-06 2018-05-11 中广核研究院有限公司 Microalloying connection method and microalloying connection structure
US10410754B2 (en) * 2016-10-11 2019-09-10 Bwxt Mpower, Inc. Resistance pressure weld for nuclear reactor fuel rod tube end plug
CN110899942A (en) * 2019-12-26 2020-03-24 西华大学 Pressure resistance welding pressurizing device and welding method for nuclear fuel rod end plug

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4857691A (en) * 1988-06-02 1989-08-15 Westinghouse Electric Corp. Burnable absorber rod end plug welding apparatus and method
EP0345499A2 (en) * 1988-06-06 1989-12-13 Westinghouse Electric Corporation End plug weld for nuclear fuel rod
US10410754B2 (en) * 2016-10-11 2019-09-10 Bwxt Mpower, Inc. Resistance pressure weld for nuclear reactor fuel rod tube end plug
CN108015445A (en) * 2017-12-06 2018-05-11 中广核研究院有限公司 Microalloying connection method and microalloying connection structure
CN110899942A (en) * 2019-12-26 2020-03-24 西华大学 Pressure resistance welding pressurizing device and welding method for nuclear fuel rod end plug

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