The factors influencing on thermomechanical behavior of TVSA and its modifications at operation

In the report it is presented description of key factors which have influence on thermomechanical behavior of TVSA at operation. Qualitative and quantitative estimations of FA form-change at affecting on them of operational loadings are given. The thermomechanical risks originating at excess of design value of FA form change are observed. Among the observed loading factors, the most significant is FA axial compression. Activities intended for control of value of axial compression, such as maneuvering by a position of PTU pads and optimization of hold-down force of the spring block are presented. It is presented experience of application of the given activities. Effect of bending rigidity value on FA form change is separately described. The methodical substantiation of application of intersector FA shuffling in view of mechanical and physical behavior is presented. Experience of intersector FA shuffling is analysed. In conclusion of the report it is the reasoning on a way of TVSA design changing with the purpose of achievement of optimum combination of thermomechanical characteristics. Keywords: TVSA, VVER-1000, form-change, FA loading, intersector FA shuffling. (author)