Natural circulation characteristics under various conditions on heavy liquid metal test loop

Liquid metal fast breeder reactors such as the sodium-cooled fast reactor and the lead-cooled fast reactor are candidates for GEN-IV nuclear energy systems. The advantages of the fast reactor design come from using liquid metal as the coolant. Small modular reactors are ideal for providing electricity to countries, offer a comparatively low initial capital investment, and offer flexibility for locations previously unable to accommodate nuclear reactors. A natural circulation system also provides potential non-proliferation benefits to the international community. The tests on liquid metal natural circulation were carried out on the liquid metal loop. Experimental studies on the isothermal natural circulation of the liquid metal were conducted in an integral test loop system, under steady state, and at varying core power source conditions ranging from 2.5 kW to 15 kW. The mass flow rate of the LBE increased rapidly from 0 to 0.36 kg/s over 500 s, and, as the core power increased, the mass flow rate of the LBE in the riser increased. As the oil temperature of the heat exchanger decreased, the temperature of the LBE also decreased. Because the temperature difference between the hot and cold legs was maintained, the mass flow rate was not affected. As the bubble injection rate was increased, the mass flow rate of the LBE in the riser also increased.198