Development of new-generation high-temperature 12% chromium steel 16Kh12V2FTaR with rapid decline of the induced activity for the atomic power engineering of russia

Designers of new-generation high-power fast-neutron nuclear power plants with sodium cooling in Russia (for example, of the DEMO thermonuclear reactor, BN-800 and BN-1800 reactors) work at providing maximum safety of the reactors and improving their economic parameters including the enhancement of the ecological safety by using structural materials with relatively rapid (up to 100 years) decline of the induced activity for parts of the active zones. For example, analysis of the operation of parts of the designed DEMO thermonuclear reactor [1, 2] shows that the structural materials should be heat resistant, have high thermocycling and radiation resistance, and be low-activating (i.e., should not contain at all or bear limited amounts of Nb, Mo, Ni, Cu, Ag, Co, and other elements) under a temperature of 300 – 650°C, damaging doses of fast neutrons (up to 200 dpa), cyclic loads (105 cycles), and compatibility with the He heat carrier. This combination of properties strongly limits the set of possible materials. From the standpoint of the level of physical, mechanical, and radiation characteristics the most suitable materials for the purpose are high-temperature 12% chromium steels of the type of EP823 and EP450 [3]. These steels have proved to be highly operable structural materials in shells of heatemitting elements and blankets of heat-emitting assemblies of BN reactors (BN600, BN-350, BOR-60, etc.). The use of such steels as structural materials for the first wall and blanket of thermonuclear reactors (TNR) is undesirable due to the exceedingly high level and long-term decline (over 1000 years) of the induced -activity that appears as a result of nuclear reactions of transmutation of the alloying elements of the steel under the action of irradiation by fast neutrons. We devoted the present work to studying some properties of steel 16Kh12V2FTaR, namely, the rate of decline of the radiation-induced radioactivity, mechanical properties (including the high-temperature strength), and radiation-induced damage in the field of neutrons, and considered the special features of the metallurgical process.