Structural Safety Analysis on Tube Sheet With Deviated Holes in Steam Generator

During the manufacturing process of the steam generator, deviated holes were detected when drilling the tube sheet. The sizes of three holes including C165-R59, C167-R59 and C168-R58 on the secondary side of the tube sheet don’t meet the design requirements, while the sizes and positions of those holes on the primary side are within design requirements. The structural safety analyses, including tube sheet strength, influence of tube sheet with deviated holes on flow induced vibration (FIV), stress analysis of plugged tubes, influence of the differential pressure between the plugged tubes and the unplugged tubes on the strength, and fretting wear between tubes caused by deviated holes, were done by the nuclear safety reviewer combined with the manufacturer and the designer. The results show that the repair plan is reasonable and feasibility. Meanwhile, in-service follow-up inspections must be strengthened to insure the quality and reliability of plugged tubes.