核动力厂预埋金属储罐老化问题及处理策略研究

Aging Issues and Mitigation Strategies of Disposable and Pre-embedded Metal Storage Tanks in Nuclear Power Plants

  • 摘要: 核动力厂预埋金属储罐通常体积庞大,有些位于地下室或半埋藏于混凝土中,在使用寿期内难以或无法更换,其寿命与运行过程中的老化效应及机理直接相关。通过对国内外预埋金属储罐老化问题深入调查研究,本文明确了应力腐蚀开裂、点蚀和缝隙腐蚀是威胁储罐安全运行最主要的3种老化机理。针对以上3种老化机理,从外观形貌、影响因素、预防措施、检查方法等方面进行了分析研究。为保证核动力厂预埋金属储罐安全可靠运行,本文聚焦于6个关键维度进行分析:评估现状、识别影响因素、确定老化机理、收集指示性数据、评估潜在后果,以及制定有效的老化管理策略。基于分析结果,提出了包括老化效应的预防、检查、监测和趋势分析,以及剩余寿命预测方法在内的系统化的老化管理策略,为储罐的定期检查、维护以及必要时的更换提供了实际可行的操作指南,以确保核动力厂的安全运行并延长储罐的使用寿命。

     

    Abstract: The pre-embedded metal storage tanks in nuclear power plants are widely used in nuclear power plants to provide water sources for safe injection into the reactor under accident conditions or to supply desalinated water, sealing water, treated water, or lubricating oil to the nuclear island, conventional island, and BOP equipment, as well as for collecting radioactive waste liquids and gases. Leakage incidents caused by aging issues of pre-embedded metal storage tanks in nuclear power plants have occurred at home and abroad, impacting the safe and stable operation of the power plant. The pre-embedded metal storage tanks in nuclear power plants are typically large in volume, with some located in basements or partially buried in concrete, making management challenging and replacement difficult or impossible during the service life. The types, uses, storage media, and operating environments of the pre-embedded metal storage tanks in nuclear power plants are diverse, with variations in aging effects and mechanisms. Due to the simplicity and predictability of uniform corrosion mechanisms, significant researches were conducted internationally on component design, aging prevention, and lifetime prediction, leading to the establishment of relevant standards. Corrosion and cracking issues caused by local harsh environments typically manifest as rapid defect expansion rates and difficulties in inspection. Therefore, such aging issues are often critical factors affecting the service life of the pre-embedded metal storage tanks, yet a systematic aging management approach is currently lacking for the pre-embedded metal storage tanks in nuclear power plants. Through in-depth investigation and research on aging issues of the pre-embedded metal storage tanks at home and abroad, stress corrosion cracking, pitting, and crevice corrosion were clearly identified as the three main aging mechanisms threatening the safe operation of the tanks in this paper. Corresponding to these three aging mechanisms, analysis and research on aspects such as appearance, influencing factors, preventive measures, and inspection methods were conducted in this paper. To ensure the safe and reliable operation of the pre-embedded metal storage tanks in nuclear power plants, the research focused on six key dimensions: assessing the current situation, identifying influence factors, determining aging mechanisms, collecting indicative data and assessing potential consequences, and formulating effective aging management strategies. Based on the analysis results, a systematic aging management strategy including prevention, inspection, monitoring, trend analysis of aging effects, and residual life prediction methods is proposed to provide practical operational guidelines for routine inspection, maintenance, and necessary replacement of tanks, ensuring the safe operation of nuclear power plants and extending the service life of the tanks.

     

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