Energy conversion system optimization study for multimegawatt space nuclear power applications

The major objective of this paper is to present a detailed description of the energy conversion system analysis and optimization procedures that were part of a broader preliminary study aimed at designing a multimegawatt (MMW) space nuclear power system. In optimizing the energy conversion system it is assumed that the most massive component of the system is the radiator and therefore the subject of optimization is the radiator mass. The closed loop Brayton and the liquid metal Rankine cycles are analyzed for a 165 MWe system. The radiator mass optimized systems based on both cycles are compared for a wide range of operating conditions. In addition, for a 165 MWe power output, the MMW power system mass is calculated using an open loop Brayton cycle. For the desired electric output, results show that the hydrogen cooled/potassium Rankine cycle is the recommended energy conversion system since it is superior to any closed loop Brayton cycle. Additionally, results show that the open loop Brayton cycle system with hydrogen working fluid has mass comparable to the selected Rankine cycle system