Leakage Causes of Pump Outlet Pipes of Steam Generator Sewage Purification System in a Nuclear Power Plant

After 15 years of operation of a domestic nuclear power plant, the outlet of the pump of the steam generator sewage purification system leaked. The reasons for the leaking of pipe were analyzed by composition analysis, metallographic inspection, scanning electron microscope observation, energy spectrum analysis and flow field simulation calculation. The results show that the thinning of the pipe wall was caused by flow accelerated corrosion (FAC) with low temperature, eventually leading to the leakage. The pipe material, geometry, pH value of the medium, temperature, dissolved oxygen content and flow rate were important factors for the FAC.