Study on Welding Joint Defects of VVER Pressurized Water Reactor Steam Generator No.111

LEI Shihe

doi:10.7512/j.issn.1001-2303.2025.07.13

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Study on Welding Joint Defects of VVER Pressurized Water Reactor Steam Generator No.111
Vol. 55, Issue 7, Pages: 118-122(2025)
Received：25 December 2024，

Revised：2025-04-11，

Published：20 July 2025
DOI： 10.7512/j.issn.1001-2303.2025.07.13
稿件说明：

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雷世和.VVER压水堆蒸汽发生器№111号焊接接头缺陷研究［J］.电焊机，2025，55（7）：118-122. DOI： 10.7512/j.issn.1001-2303.2025.07.13.

LEI Shihe.Study on Welding Joint Defects of VVER Pressurized Water Reactor Steam Generator No.111[J].Electric Welding Machine, 2025, 55(7): 118-122. DOI： 10.7512/j.issn.1001-2303.2025.07.13.

摘要

蒸汽发生器作为核电厂一回路核安全I级设备，其运行可靠性直接关机组经济效益与安全。通过分析VVER压水堆核电机组用 PGV-1000蒸汽发生器的集流管DN1200与蒸汽发生器壳体连接焊缝№111-1和№111-2焊缝，发现其存在类似“口袋” 的死角设计缺陷。通过分析俄罗斯新沃罗涅日核电站等在运机组的大修数据，该类焊缝在机组启动后 5~20 年内易出现结构强度丧失，主要表现为裂纹等缺陷。研究表明，缺陷成因与多重因素相关：死角区域受不均匀热冲击，介质流动不畅导致铜离子等杂质堆积，加速裂纹萌生与扩展；焊接残余应力及结构复杂性进一步加剧了损伤。针对上述问题，从制造环节提出改进措施：优化焊接工艺（如根部氩弧焊充氩保护、对称施焊控制变形）、完善焊工认证与无损检测体系、严格执行 620-640℃焊后热处理以降低残余应力。运行阶段建议通过添加化学药剂抑制沉积物、提高清洗频率、定期涡流 / 超声检测，超设计寿命机组可采用 “口袋” 钝化与运行负荷优化以延缓缺陷恶化。研究成果为 VVER 堆型蒸汽发生器№111 焊缝的制造、运维提供了理论与实践指导，亦为其他堆型蒸发器类似结构的缺陷控制提供参考。

Abstract

The steam generator

as a nuclear safety Class I equipment in the primary circuit of a nuclear power plant

has its operational reliability directly related to the economic benefits and safety of the power unit. Through analyzing the collector tube DN1200 and the connecting welds №111-1 and №111-2 of the PGV-1000 steam generator used in VVER pressurized water reactor units

a design flaw similar to a "pocket" dead angle was discovered. By analyzing the overhaul data of operating units such as the Novovoronezh Nuclear Power Plant in Russia

it was found that such welds are prone to structural strength loss within 5-20 years after the unit starts operation

mainly manifested as defects like cracks. The study indicates that the causes of the defects are related to multiple factors: uneven thermal shock in the dead angle area

impeded medium flow leading to accumulation of copper ions and other impurities

accelerating crack initiation and propagation; residual welding stress and structural complexity further exacerbate the damage. To address these issues

improvements in the manufacturing process are proposed: optimizing welding techniques (such as argon protection at the root of the arc welding

symmetrical welding to control deformation)

enhancing welder certification and non-destructive testing systems

and strictly implementing post-weld heat treatment at 620-640 ℃ to reduce residual stress. During the operational phase

it is recommended to add chemical agents to inhibit deposits

increase cleaning frequency

conduct regular eddy current / ultrasonic tests

and for units exceeding their designed lifespan

"pocket" passivation and operational load optimization can be adopted to delay defect deterioration. The research results provide theoretical and practical guidance for the manufacturing and operation & maintenance of the VVER reactor type steam generator weld №111

and also offer references for defect control in similar structures of other reactor types.

关键词

Keywords

references

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