核电蒸汽发生器胀接接头质量事故分析及应对措施研究

Analysis and Research on Quality Accident of Expanded Joint of Steam Generator Tube in Nuclear Power Plants

全深度液压胀接技术是核电机组蒸汽发生器及其他换热器管子-管板接头普遍采用的制造工艺,具有液压胀接压力均匀、管壁减薄均匀、管子和管板的残余应力小、接头质量稳定等优点。液压胀管时需将300兆帕水介质封闭在胀管区域,一旦密封失效,将直接影响接头质量,胀接过程中易出现未胀合缝隙长度过大(欠胀)、过胀、肿胀、漏胀、重复胀接以及造成换热管划痕等质量问题。对国内外蒸汽发生器制造厂出现的典型胀接缺陷归类并进行原因分析,结合工程经验获得良好经验反馈及应对纠正措施,为核电蒸汽发生器管子管板接头胀接工序提供指导。

Full-depth hydraulic expansion technology is a common manufacturing process for tube-tubesheet joints of steam generators and other heat exchangers in nuclear power units.It has the advantages of uniform hydraulic expansion pressure,uniform tube wall thinning,small residual stress of tube and tubesheet,stable joint quality,etc.During the hydraulic expansion,the 300 MPa water medium needs to be sealed in the expansion pipe area.Once the sealing fails,the joint quality will be directly affected.In the process of hydraulic expansion,quality problems are easy to occur such as too long unexpanded gap(under-expansion),over-expansion,missed expansion,repeated expansion and causing scratches on heat exchange tube.The typical expansion defects of steam generator manufacturers at home and abroad were classified and their causes were analyzed,which provides guidance for the tubing-tubesheet joint expansion procedure of steam generator in nuclear power plant in combination with good experience feedback and corrective measures obtained from engineering experience.