Thermal-hydraulic efficiency of a modular reactor power plant by using the second law of thermodynamic

•Energy quality and the cost of energy stream are investigated in SMRs.•Exergy losses are calculated in main components of a SMR.•SMR technology is safer due to the smaller reactor temperature. Small modular reactor power plants (SMR) plants are among the new nuclear technologies. These plants are greatly safer due to the operational and technological differences comparing to traditional nuclear technologies. Thus, this security and safe, clean, and cheaper energy generation makes it the best hope for nuclear energy development in the future. Energy and exergy investigation of SMR power plants is one of the main ways to have an insight into the technology. In this paper, an SMR power plant previously introduced by FSAR is adapted and investigated exergetic, energetic, and exergoeconomically. The main aim of this paper is to introduce the SMR power plants and also to investigate the energy quality and the cost of energy stream in these plants. The results of this paper show that nuclear power plants with SMR technology are safer due to the smaller reactor temperature, fuel quantity, and stream mass flow. However, these lesser values don’t decrease the efficiency of the plant, and its electricity cost and total exergy and energy efficiencies are comparable to the conventional nuclear power plants.