Theoretical and Experimental Analysis of the Bistable Convection Loop for Liquid-Metal-Cooled Reactor Emergency Core Cooling

An emergency core cooling system incorporating a bistable convection loop (BCL) for current passive liquid-metal-cooled reactors is proposed. The system has two stable operating modes. During the off mode, the system is in a pure conduction mode and transfers very little heat. In the on mode, the system switches to the low-resistance configuration of a closed natural convection loop and transfers significant amounts of heat. The switching occurs passively because of changes in the reactor temperature. Theoretical and experimental analysis shows that a BCL designed to remove 7% of peak reactor power in the on mode loses only 0.0007% in the off mode, yielding a ratio of 10 000:1.