Effect of Tube Support on the Failure of Steam Generator Tubes with Through-WallCircumferential Cracks

摘要

The assessment of steam generator tubes with defects is of great importance for the life extension of steamrngenerators. Circumferential through-wall cracks are the most severe of all tube circumferential defects, and usually requirernplugging of the affected tubes. The assessment of the tubes with through-wall circumferential cracks or cracks projected tornbecome through-wall can be conducted using the failure assessment diagram (FAD) approach. This approach requires therncalculation of the stress intensity factor and the limit load. The available stress intensity factor and limit load solutions forrncracked tubes do not include the constraining effect of the tube supports. In the present paper, it is shown that this can bernoverly conservative. Solutions for stress intensity factors and limit loads are presented for tubes with circumferentialrnthrough-wall cracks including the effect from the tube support plates. Different values of support spacing are considered.rnBased on these solutions, the assessment of a typical steam generator tube is demonstrated.