Cause Analysis of Booster Pump Shaft Cracking in Nuclear Power Plant

The cracking Booster pump shaft is carried out macroscopic examination, crack analysis, metallographic examination, chemical composition analysis, mechanical properties (tensile, impact) analysis, and combined with the pump shaft installation and operation, determine the direct cause of shaft cracking is crevice corrosion, the root cause include O ring in booster pump machine seal sleeve does not meet the requirement, O ring installation damage, and the clearance between pump shaft and machine seal sleeve is too small. According to the root cause of the pump shaft cracking, relevant corrective actions have been formulated, such as changing model of O ring in booster pump machine seal sleeve, change the clearance between pump shaft and machine seal sleeve, increase anti-corrosion coating or protective sleeve on pump shaft etc.