Failure assessment of degraded baffle former bolts retrieved from a nuclear power plant

IF 4.4 2区工程技术 Q1 ENGINEERING, MECHANICAL

Engineering Failure Analysis Pub Date : 2025-04-22 DOI:10.1016/j.engfailanal.2025.109640

Hwan-Jae Joo , Yoon-Suk Chang , Seong Sik Hwang , Seung Jin Oh , Young Jae Maeng

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引用次数: 0

Abstract

While baffle former bolts (BFBs) connect baffle and former plates, ensuring the alignment and stability of baffle former assembly, cracking of the bolts has been reported within their design life and the risk of such failures increases with long-term operation. This study presents a systematic failure assessment of degraded BFBs retrieved from a nuclear power plant, focusing on defect causes and fracture mechanics. Global thermal and structural analyses were first conducted using the finite element method with user-subroutines to account for operational conditions, gamma heating and four irradiation-induced age-related degradation mechanisms (ARDMs). Subsequently, local structural analyses were performed to evaluate detailed engineering parameters of the degraded BFBs as well as the baffle former assembly. Finally, crack growth behaviors of two defective BFBs were examined using the extended finite element method (XFEM) based on the local structural analysis results. Building upon these findings, the failure assessment demonstrated synergistic and complex effects arising from the irradiation-induced ARDMs and structural asymmetry of the baffle plates. Furthermore, crack shapes and sizes of the defective bolts were accurately predicted by the XFEM.

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某核电站退化折流板前螺栓失效评估

导流板前螺栓（bfb）连接导流板和导流板，确保导流板组件的对准和稳定性，但螺栓在其设计寿命内出现了开裂的情况，并且随着长期运行，此类故障的风险也在增加。本研究提出了从核电厂回收的退化BFBs的系统失效评估，重点是缺陷原因和断裂力学。首先使用有限单元法和用户子程序进行了整体热和结构分析，以考虑操作条件、伽玛加热和四种辐射诱发的年龄相关降解机制（ARDMs）。随后，进行了局部结构分析，以评估退化bfb和折流板前组件的详细工程参数。最后，基于局部结构分析结果，采用扩展有限元法对两种缺陷bfb的裂纹扩展行为进行了分析。在这些发现的基础上，失效评估证明了辐射引起的ardm和挡板的结构不对称所产生的协同和复杂效应。利用XFEM对缺陷螺栓的裂纹形状和尺寸进行了准确预测。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Engineering Failure Analysis 工程技术-材料科学：表征与测试

CiteScore

7.70

自引率

20.00%

发文量

956

审稿时长

47 days

期刊介绍： Engineering Failure Analysis publishes research papers describing the analysis of engineering failures and related studies. Papers relating to the structure, properties and behaviour of engineering materials are encouraged, particularly those which also involve the detailed application of materials parameters to problems in engineering structures, components and design. In addition to the area of materials engineering, the interacting fields of mechanical, manufacturing, aeronautical, civil, chemical, corrosion and design engineering are considered relevant. Activity should be directed at analysing engineering failures and carrying out research to help reduce the incidences of failures and to extend the operating horizons of engineering materials. Emphasis is placed on the mechanical properties of materials and their behaviour when influenced by structure, process and environment. Metallic, polymeric, ceramic and natural materials are all included and the application of these materials to real engineering situations should be emphasised. The use of a case-study based approach is also encouraged. Engineering Failure Analysis provides essential reference material and critical feedback into the design process thereby contributing to the prevention of engineering failures in the future. All submissions will be subject to peer review from leading experts in the field.