Prospects for the development of the concept of a safe nuclear reactor BREST of maximum limiting power for nuclear energetics of the middle of the XXI century

Abstract

In Russia (JSC NIKIET) a project of a fast reactor BREST-1200 is being developed. The article analyzes the safety of the BREST reactor with maximum limiting power (BREST-2000, -2400). In BREST reactors with an electric power of 1200 MW and more, the void reactivity effect of can be positive. The most dangerous scenario is associated with the entrainment of bubbles into the central part of the core (with a volume fraction of bubbles of 50 … 60%). In this case, the magnitude of the void reactivity effect is several times higher than the effective fraction of delayed neutrons β. For the BREST-2400 reactor, the maximum void reactivity effect is about 7 β (for BREST-2000, about 6 β). When other ATWS are implemented against the background of erosion and corrosion of structural steel, the total introduced reactivity can also exceed β, which will lead to an accident. To ensure safety, it is necessary to adjust the design solutions. When used as a coolant, lead extracted from thorium ores (with a concentration of 208Pb isotope from 75 to 98%) and tungsten coatings of fuel claddings, the void reactivity effect is negative even in the BREST-2400 reactor, and when switching to a new cermet fuel (0.8 MN - 0.2 U) it is easy to ensure the safety of the reactor.