possibility of exercising safety functions without external power supply, as well as making control through “human–machine” interface; to ensure conditions required to avoid evacuation of the population living near a Nuclear power plant in case of severe accidents. Safety barriers VVER-TOI project shows implementation of the following principles ensuring the modern concept of the repetitive defense in depth: to create a number of the consequential barriers preventing emission of the radioactive products, which are accumulated during operation to environment. Nuclear fuel (fuel matrix and fuel-element cladding), boundaries of the coolant circuit, cooling reactor core (reactor vessel, pressurizers, main circulating pumps, steam generator collectors, primary circuit pipelines and connected systems, heat-exchanging steam generator tubes), hermetic fences of the premises with located equipment and reactor plant pipelines inside can serve as the barriers for Nuclear power plants with VVER reactors. high level of reliability caused by implementation of the special requirements to quality assurance and control while designing, manufacturing, installation, keeping the level achieved during operation through control and diagnostics (ceaseless or periodical) of physical barriers conditions, elimination of the revealed defects, damages and failures; to establish protective and localizing systems intended for prevention of the physical barriers damage, restriction or mitigation of the radiation repercussions in case of possible infringement of normal operation margins and conditions, and in case of accidents. Nuclear power plant protection against external impacts Natural disasters and human-induced impacts specifying site conditions are accepted taking into account possibility of constructing Nuclear power plants with VVER-TOI reactors in various geographical regions, as well as in the regions characterized by different human-induced impacts. The most important impacts, which parameters affected significantly technical solutions on VVER-TOI project are listed below: Seismic impacts Impacts connected with aircraft crashes Air impact waves Floods and storms Tornadoes Nuclear power plant systems and components as a part of the base - case project are developed by reference to the following natural disasters and design human-induced impacts: Safe Shutdown earthquake of intensity up to 8 on MSK-64 scale at maximum horizontal acceleration on a free ground surface of 0.25 g Design-Basis earthquake of intensity up to 7 on MSK-64 scale at maximum horizontal acceleration on a free ground surface of 0.12 g Crash of a 20 t aircraft at a speed of 215 m/s as design initial event Crash of a 400 t heavy aircraft at a speed of 150 m/s as beyond design initial