Fatigue Fracture Failure Analysis and Design Improvement of the Rectifier Plate in a Residual Heat Removal Pump

LI Zhe; WU Shenglong

doi:10.7512/j.issn.1001-2303.2026.02.14

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Fatigue Fracture Failure Analysis and Design Improvement of the Rectifier Plate in a Residual Heat Removal Pump
Vol. 56, Issue 2, Pages: 119-126(2026)
Received：29 June 2025，

Revised：2025-08-20，

Published：20 February 2026
DOI： 10.7512/j.issn.1001-2303.2026.02.14
稿件说明：

移动端阅览

李哲，吴声龙.核电机组余热排出泵整流板断裂失效分析与设计改进［J］.电焊机，2026，56（2）：119-126. DOI： 10.7512/j.issn.1001-2303.2026.02.14.

LI Zhe, WU Shenglong.Fatigue Fracture Failure Analysis and Design Improvement of the Rectifier Plate in a Residual Heat Removal Pump[J].Electric Welding Machine, 2026, 56(2): 119-126. DOI： 10.7512/j.issn.1001-2303.2026.02.14.

摘要

针对国产化“华龙一号”核电站余热排出泵在出厂试验中出现的整流板断裂事件，开展了系统性失效分析与结构优化研究。通过断口失效分析、焊接工艺审查、应力水平测试及有限元模拟，确定断裂失效是因为单悬臂整流板结构设计不合理，导致耐久试验过程中焊缝区域应力集中，在流量调节瞬态工况下，整流板焊趾处最大应力达197.77 MPa，超过了设计标准中奥氏体不锈钢的疲劳极限94 MPa，从而引发低周高应力疲劳断裂，端口表面呈现清晰的疲劳断裂的贝壳线和断裂辉纹。针对断裂发生的实际原因，对整流板进行结构优化设计，将单片式结构调整为双片对称式整流板，并将单片径向长度缩减至原尺寸1/2，轴向长度缩短至120 mm，焊接接头改为全焊透结构。经应力水平测试和有限元分析计算，优化后整流板动应力幅值下降82%以上，焊趾处最大瞬态应力降至21.1 MPa，显著低于疲劳极限。经200 h耐久试验后的整流板无损检测合格，运行参数稳定，满足核电设备安全要求。本研究不仅保障了项目供货进度，更为核电关键设备国产化设计提供了重要的工程经验与数据支持。

Abstract

This paper presents a systematic failure analysis and structural optimization study addressing the rectifier plate fracture incident observed during factory acceptance testing of the residual heat removal (RHR) pump for the domestically developed "Hualong One" nuclear power plant. Through fracture surface analysis

welding process review

stress level testing

and finite element simulation

the failure was attributed to the irrational structural design of the single cantilevered rectifier plate

which induced stress concentration in the weld zone. Under transient flow regulation conditions

the maximum stress at the weld toe of the rectifier plate reached 197.77MPa

exceeding the fatigue limit of 94 MPa for austenitic stainless steel specified in the design standard，triggering low-cycle high-stress fatigue fracture. To resolve this issue

an optimized dual-symmetric rectifier plate design was implemented: the radial length of each plate was reduced to half of the original dimension

the axial length was shortened to 120 mm

and the welded joint was modified to a full-penetration structure. Post-optimization analysis showed that the dynamic stress amplitude of the rectifier plate decreased by over 82%

with the maximum transient stress at the weld toe reduced to 21.1MPa，significantly below the fatigue limit. Following a 200-hour endurance test

the optimized rectifier plate passed non-destructive testing (NDT)

exhibited stable operational parameters

and met nuclear safety equipment requirements. This research not only ensured project delivery timelines but also provided crucial empirical data and engineering insights to support the localized design of critical nuclear power equipment.

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