Steam generator is one of the most important components of nuclear power plants regarding functionality and safety. Crucial requirement in the work of nuclear power plants, and that arises from safety requirements, is the retaining of the integrity of the primary circuit, thus a steam generator as well. The surface of the steam generator tube bundle makes for more than 50% of the overall surface of the primary circuit under pressure. Defects of the tube bundle can lead to fission products´ release to the secondary circuit, and then, through the condenser, to the environment. The main task of every nuclear power plant owner is to establish the balance in taking precautions such as monitoring, inspection and corrective actions, with the aim of retaining the steam generator integrity. The steam generator integrity assessment is the key factor in achieving the mentioned aim. Performing the mentioned task implies conducting a wide range of researches that need to be executed by a nuclear power plant owner: - Research of degradation mechanisms that occur on steam generator - Research of available technology of steam generator tube inspection that can meet the requirements of as-found condition determination - Implementation of the appropriate methodology for identifying the structural integrity of tube at the beginning and at the end of the cycle - Quantification of measurement uncertainties - Selection of the strategy for conducting the structural integrity analysis - Verification of the model for identifying the structural integrity of tubes with data of artificial defects and if possible real defects On the basis of the mentioned research, a program of inspection is established, that defines the scope of inspection, inspection techniques that need to be applied, and the qualification level of the staff assigned for performing the inspection. Inspection data enable the execution of the entire procedure of identifying the structural integrity of steam generator tubes at the beginning, as well as at the end of the cycle. This thesis explores all mentioned elements necessary for identifying the steam generator tube structural integrity. Particular impact factors and manners of their identification are presented. Special attention is paid to inspection technique and defining burst pressure relationship, using tubes with artificial (mechanical) flaws. For the case of axial flaws on the free span, comprehensive laboratory researches have been conducted. They enabled the identification of the burst pressure relationship and identification of all accompanying uncertainties, relational uncertainty, material property uncertainty, measurement, and growth uncertainty. Tube material property uncertainty is identified for working conditions of steam generator (300oC), so burst pressure relationship is reduced to operating conditions. Valuable contribution to research of structural integrity of tubes was made by using tubes with real defect from the steam generator. Laboratory researches on pulled out tubes were conducted, for the purpose of identifying measurement uncertainties, in the manner that all flaws that had previously been identified by the eddy current method underwent destructive examination, which generated highly valuable data regarding nondestructive measurement uncertainty. A certain number of pulled out tubes was used for identifying burst pressure relationship, so they were subject to burst pressure testing for different flaws. Eventually the structural integrity for tubes with real defect was identified. Above mentioned enables a scientific approach of identifying the structural integrity of tubes using contemporary mathematical models to be established on VVER steam generators. Comprehensive laboratory research for particular defects occurrence was conducted, that had not been conducted until now. For the needs of this thesis, researches were conducted on tubes with artificial flaws axially oriented on the free span, as well as on tubes with real defects (combination of pitting and stress corrosion cracking). This will allow owners of nuclear power plants a new approach in defining the structural integrity of steam generators tubes which enables improved reliability and safety in the nuclear power plant operation.