Laser Welding Method for Guide Sheath of Guide Tube in Nuclear Reactor

Abstract

The invention belongs to the technical field of welding, and discloses a laser welding method of guide sheaths of a guide cylinder in a nuclear reactor. The laser welding method comprises the following steps: (1) machining butt planes of guide sheath weld assemblies until the machining precision of the butt planes reaches the degree of zero defect by visual inspection and a liquid penetration test; (2) positioning and then clamping truncated edges of the guide sheath weld assemblies through a clamp, wherein the gap between the butt planes is less than or equal to 0.02mm; (3) positioning the weld assemblies in the length direction of a welding line; (4) under the protection of nitrogen, performing laser welding on a butt joint of the guide sheath weld assemblies; (5) after the welding, performing insulation treatment at the temperature of 400+ / -15 DEG C for not less than 2 hours. According to the laser welding method provided by the invention, the welding process is simple, the welding speed is fast, the welding formation is excellent, the physical and chemical properties are excellent, the deformation is controllable, and the working environment is safe.

Description

technical field [0001] The invention belongs to the field of welding technology, in particular to a laser welding method for a guide sheath of a guide cylinder in a nuclear reactor. Background technique [0002] The guide cylinder assembly is an extremely important part of the internal components of the nuclear reactor pressurized water reactor. It requires high manufacturing precision and strict requirements on the control of welding deformation. In a 1000MW pressurized water reactor, the number of guide cylinders is usually 69 sets, and each set of guide cylinders contains 8 sets of guide sheath assemblies (or "double tube assemblies", 4 sets of 45° guide sheaths and 4 sets of 90° guide sheaths), Each unit contains 552 sets of guide sheath assemblies. The number of 1400MW PWRs is more, 712 sets. [0003] The existing welding method is vacuum electron beam welding. Since the material is austenitic stainless steel, electron beam welding under vacuum conditions can achieve ...

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Problems solved by technology

[0004] However, the existing vacuum electron beam welding method needs to be moved into the vacuum chamber after the assembly station is assembled, and then the vacuum operation is performed. The welding can only be performed after the vacuum degree reaches a very high requirement. After welding, the gas filling operation is required. After returning to normal pressure, the weldment can be taken out for subsequent inspection and processing

Vacuum chamber assembly, vacuuming, inflation and other operations are complicated, and the time required is several times or even ten times longer than the welding time. For the welding of a large number of guide sheath components, the efficiency is low

In addition, vacuum electron beam welding must increase X-ray protection, which has potential safety hazards

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