A PREDICTION METHOD OF WEAR DEPTH CONSIDERING THEGAP BETWEEN TUBE AND SUPPORT IN STEAM GENERATOR

摘要

When the tube contacts to support plate or anti-vibration bar in steam generator of the nuclear power plants,the contact area is worn out by their relative displacement and contact force. The major flow-induced vibrationmechanisms such as fluid-elastic and turbulence excitation can cause the various types of tube wear. It isgenerally accepted that the tube wear due to vibration is affected by the presence of gap clearance between tubeand support plate. Connors showed that the wear depth of tube could be estimated by using the relationshipbetween wear volume and sliding distance for contact time. Au-Yang predicted the wear depth by using thenonlinear characteristics of normal work rate to contact time. In this study, a method for prediction of tube wearincluding gap between tube and its support has been proposed. A proposed method was derived from previousmethodologies for obtaining the wear depth of tubes. The effect of gap size on the steam generator tubes wear isalso analyzed and estimated by the proposed methods which include the relations of wear depth versus normalwork rate and wear depth. It was investigated that normal work rates is decreased as the gap is increased, andnormal work rates are decreased as operating time is increased. Thus, I was conclude gap effect is decreased asoperating time is increased. When the normal work rate is less than 10 mw using wear coefficients withgenerally accepted level, the effect of gap size on the normal work rate is negligibly small. A proposed methodmay be applicable to the evaluation of gap effects under the fluid conditions of turbulence excitation in designand maintenance of the nuclear power plant.