[en] As a result of international discussion concerning the problems of radiation embrittlement and integrity of the pressure vessel of Kozloduy-1 NPP it was recognised necessary to perform renewed analyses of PTS conditions with the aim of obtaining the basis for decision making on further operation. The most important results of structural analyses and fracture mechanic analyses obtained by Gidropress are presented. Based on experience of Siemens, Westinghouse and OKB Gidropress integrity tests, three accident conditions are chosen for the analyses: break of steam generator steamline; break of pressurizer injection line; inadvertent opening of the pressurizer safety valve followed by its closing. The calculations were performed according to the Russian regulatory requirements