| Issue |
E3S Web Conf.
Volume 561, 2024
The 8th International Conference on Energy, Environment and Materials Science (EEMS 2024)
|
|
|---|---|---|
| Article Number | 02018 | |
| Number of page(s) | 5 | |
| Section | Intelligent Environment Planning and Green Development | |
| DOI | https://doi.org/10.1051/e3sconf/202456102018 | |
| Published online | 09 August 2024 | |
The Cause Analysis of Valve Stem Bolt Failures in Nuclear Power Plant
1 Mechanical Maintenance Department, ShandongNuclear Power Co.,Ltd., Haiyang, Shandong 216600, China
2 SPIC Power Station Operation Technology (Beijing) Co.,Ltd., Beijing 112209, China
* Corresponding author’s e-mail address: fangqishu820726@163.com
The shaft of the electric isolation valve at the outlet of the seawater tank pump in a nuclear power plant fractured due to bolt failure, resulting in detachment and loss of electrical switching function. Upon disassembly, it was discovered that all connecting bolts on the frame were fractured. Macroscopic examination, chemical composition analysis, hardness testing, metallographic examination, scanning electron microscope (SEM) observation, and energy spectrum analysis were performed on the fractured bolts. Results revealed significant deviation from design specifications for stainless steel austenite in terms of their chemical composition; instead they consisted of low-alloy steel (40Cr). High-strength bolts exposed to marine environments are susceptible to corrosion-induced stress cracking or hydrogen embrittlement leading to fracture. Replacement is recommended as a preventive measure against corrosion-induced bolt failure.
© The Authors, published by EDP Sciences, 2024
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