Multiple-Reheat Brayton Cycles for Nuclear Power Conversion with Molten Coolants

Abstract

Gas-turbine power conversion systems can have lower capital costs than comparable steam-turbine systems due to their higher power density. The recent commercialization of magnetic bearing systems for large turbomachinery now makes direct recuperated Brayton cycles the preferred power conversion choice for gas-cooled reactors. This paper presents a multiple-reheat closed gas cycle optimized to use energy input from liquid-metal or molten-salt coolants with temperatures as low as 550 to 650°C. By utilizing reheat, these molten coolant gas cycles (MCGCs) have the potential for substantially higher thermal efficiency than current gas-cooled reactors if used with comparable turbine inlet temperatures. The MCGC system also eliminates the need for steam generators, which removes the potential for chemical reactions between the molten coolant and steam, and greatly simplifies the control of tritium for fusion energy systems.