某电站核岛设备冷却系统的传热管频发泄漏故障，发生泄漏的传热管材料为紫铜，泄漏点位于弯管和直管之间的焊缝上。采用化学成分分析、金相检验、扫描电镜及能谱分析、X射线衍射分析等方法分析了该传热管穿孔泄漏的原因。结果表明：铜管母材基本完好，整个泄漏通道沿焊缝发展，泄漏通道在管道内表面的开口宽度大于管道外表面的开口宽度，失效起源于铜管内侧焊缝上的缺陷；焊丝中的磷元素含量超标导致的焊缝组织中的缺陷，以及焊缝中存在大量气孔是引发泄漏的主要原因。

In a power station, leakage failure occurred to a heat transfer tube of the nuclear island cooling system frequently. The leaked heat transfer tube was made up of red copper, and the leak points lay on the welding seam between the elbow tube and straight tube. The leakage reasons were studied by chemical composition analysis, metallographic examination, electron microscope and energy spectrum analysis, X-ray diffraction analysis and so on. The results show that:the basic metal of the copper tube didn't suffer damage; the leakage path developed alone the welding seam, and the width of the leakage path in the inner tube was wider than that in the outer tube; the failure was originated from the defect of the welding seam in inner tube; the excess of phosphorous resulted in the defect in the welding seam, and plenty of bubbles existed in the welding seam, which were the main reasons of the leakage.