EVALUATION OF THERMOCYCLIC LOADS IN THE WELDING UNIT OF THE 'HOT' COLLECTOR AND THE BRANCH PIPE OF THE PGV-1000 STEAM GENERATOR

摘要

Safe operation of nuclear power plants is impossible without providing strength of their equipment and pipelines in view of their equipment and pipelines in view of real loading conditions. In this context, it becomes clear why each case of initiation of crack-type damages in pieces of equipment presents significant interest for experts in the field of strength of materials. During operation within the design service life, cracks were detected in the welding unit of the "hot" collector and the branch pipe of the PGV-l000 steam generator of a nuclear power plant with a VVER-l000 reactor. The investigations performed in this connection failed to reveal the cause of damage initiation All the discovered damages (cracks) were located practically in the same place of the welding units of the "hot" collector and the branch pipe, which, in this case, indicates the presence of a common factor of loading that acts in the unit and was not considered in strength calculations earlier.