Sodium-Cooled Fast Reactor

The sodium-cooled fast reactor is a type of reactor which utilizes sodium as a coolant, with its blanket region containing rods of natural uranium. It is used on nuclear power plant where the reactor works on fast neutrons and there is no moderator, with the core being small and compact. The first one was the US Experimental Breeder Reactor 1, which started in 1951, with a generation capacity of only 200 kWe; the coolant was sodium-potasium alloy.

The sodium-cooled fast reactor is a pool type design. The pool of sodium is contained in a vessel, with the sodium being pumped through the core by pumps that are set up within the pool. Then the hot sodium flows through an intermediate heat exchanger, with the heat being transferred to a second sodium-cooled loop. The latter transfers the heat to a water/steam loop via the steam generator. This tertiary loop system makes sure that any radionuclides produced in the primary vessel are not transferred to the steam generator.

The sodium-cooled fast reactor is a type of liquid metal-cooled reactor. Its main advantage is that it has a desirable thermophysical properties as the coolant has a low melting point, and it can be either sodium or potassium, which has low neutrons absorption. Sodium has a high thermal conductivity, with a lower specific heat than heavy water, and it has a high boiling point, too. The disadvantage is that sodium is highly reactive to oxygen and water. This is a potential problem of isolation of the sodium and water cooling loops.