[en] The process of nuclear safety level increase and operational reliability of NPP V-1 has been realized continuously since units commissioning. The significant step was made after 1989-90 when more national and international expert missions were realized on NPP V-1 for evaluation of design level, safety and reliability. On the base of recommended measures many improvements were realized during the years 1991-93 in the frame 'Small reconstruction of NPP V-1'. At the same time the preparation of 'Gradual reconstruction of NPP V-1' has been started. This project has been realized during spread outages for general repairs and refuelings in the years 1996-1999. The main purpose of this reconstruction is to increase the nuclear safety level and operational reliability to the internationally acceptable level which will establish technical assumptions for safe and reliable operation of the units NPP V-1 at least until the end of the design lifetime. (author)