Abstract: Zirconium alloy has the advantages of low thermal neutron absorption crosssection,good corrosion resistance and mechanical properties,and is often used to make cladding and end plugs of nuclear fuel rods in pressurized water reactor. In the manufacturing of fuel rod,zirconium alloy claddings and end plugs need to be seal-welded by gas tungsten arc welding(GTAW),however,the performance of the seal welding zone of fuel rod may deteriorate due to excessive tungsten content. To clarify the effect of tungsten content in the seal welding zone on the microstructure and corrosion behavior of the top end plugs of N36 zirconium alloy fuel rods,the tungsten content,microstructure and micro-area composition of the unwelded top end plugs,as well as welded ones with qualified and excessive tungsten content,were investigated by X-ray fluorescence spectrograph,metallographic microscope and scanning electron microscope. The fuel rods were subjected to corrosion test for 72 and 336 h in a superheated steam at 400 ℃ with a pressure of 10. 3 MPa. The results showed that(a) the tungsten contents of the top end plugs of unwelded and welded fuel rods with qualified and excessive tungsten content were 175,183,and 379 cps,respectively(recommended threshold being 235. 22 cps);(b) the grain sizes were 150 μm in the seal welding zone of top end plug of the welded fuel rod and nearly 4 μm in the top end plug of unwelded fuel rod;and(c) the top end plugs of three fuel rods were all free from tungsten inclusion,and uniform dense oxide film with acceptable thickness formed on them after corrosion test,indicating that the excessive tungsten content has no significant adverse effect on short-term corrosion behavior of the seal welding zone of top end plugs of N36 zirconium alloy fuel rod.