FACTORS AFFECTING STEAM GENERATOR TUBE BOW

One of the challenges in straight shell-and-tube Steam Generator design is to avoid the tube to tube wear that can arise during operation due to higher than anticipated compressive tube loads and the resulting tube bow that can occur. Tube bow becomes significant when the compressive load in the tube exceeds its critical buckling capacity. This excessive load does not lead to unstable collapse of the tube as the axial load in the tube is displacement controlled. However, it does lead to significant lateral deformation for a very small increase in axial load/displacement. In this paper, several factors are investigated to determine their influence on the onset of tube bowing. Based on the studies performed in this paper there are factors that play a significant role in the behavior of steam generator tubes that have not typically been addressed in associated design analyses. Failure to address these factors can lead to unexpected behavior, premature degradation of steam generator performance, and possibly pressure boundary failure. A thorough understanding of these factors is necessary to ensure that a given design will perform as expected.