Performance analysis of the closed Brayton power cycle in a small-scale pebble bed gas cooled reactor using different working fluids

Highlights: • Thermodynamic analysis was conducted for small pebble bed modular gas cooled reactor. • Different gases viz. air, CO₂, N₂ and He were studied as working fluids. • The studied gases were investigated in terms of system performance parameters. - Abstract: A performance analysis is carried out for a 60 MW_th Advanced Atomic Cogenerator for Industrial Applications that is a pebble bed high-temperature gas cooled reactor with an indirect Brayton power conversion system. Four different gases viz. air, CO₂, N₂ and He were studied as secondary cycle working fluids. Specific work output and power generation efficiency are calculated. In addition, the total thermal efficiency for the steam production process is estimated. Our results indicate that over a wide range of some operating conditions, helium gives the highest power generation efficiency, while N₂ and air provide a better specific power output. Finally, the highest cogeneration-steaming rate was noticed for the CO₂ cycle.