The article discusses new materials for high-power fast nuclear power reactors. Among promising materials, nanomaterials, composite materials, and powder materials are considered. The physical principles of using new materials are analyzed. Nanomaterials and nanopowders can be used in the production of nuclear fuel and as additives to structural materials of fuel pin cladding. The article discusses reactors with liquid lead coolant. These reactors will form the basis of large-scale nuclear power in Russia, the transition to which is predicted to be by the middle of the twenty-first century. To improve the safety of reactors, it is proposed to use innovative cermets fuel with additives of enriched or depleted uranium nanopowder. It is proposed to use lead extracted from thorium ores as a coolant. A reactor with an electrical capacity of up to 3 GW is characterized by negative void and density reactivity effects under the most dangerous scenario of their implementation. It is resistant to any emergency situations, including anticipated transient without scram. The proposed innovations (new materials of the core) will allow creating a high-temperature reactor, including an abnormally high power. The article examines chemical reactions of free hydrogen formation in heat exchangers and the core, which can be realized in an accident with contact of lead and steel components with superheated water vapor of the second circuit. A hydrogen explosion is possible only upon contact with atmospheric air during a hypothetical destruction of the reactor or heat exchanger. This can lead to aggravation of the accident.