Nuclear heated open air-Brayton cycles have been investigated both as topping cycles for combined cycle Brayton-Rankine cycles and as standalone recuperated Brayton cycles. The peak turbine inlet temperature chosen for the analysis was 933 K for a range of Generation IV molten salt reactors or lead cooled reactors. A baseline power level of 25 MW(electric) was chosen to be representative of some of the small modular reactor concepts being considered. Extensions to higher temperatures and power levels were evaluated. Thermal efficiencies in the 45% to 46% range can be achieved by both the combined cycle systems and the recuperated systems, though the combined cycle systems achieve about a 1% to 1.5% improvement over the recuperated systems.
The nuclear heated open air-Brayton systems have several advantages over current light water reactor and other Generation IV systems. The analysis demonstrates that the cycle thermal efficiencies are higher than other proposed systems. The gas turbine hardware is readily available over a broad range of power levels. And both the combined cycle and recuperated systems require significantly less circulating water for waste heat rejection than any other proposed systems.