Transcritical CO2 mixture power for nuclear plant application: Concept and thermodynamic optimization

The conventional steam power cycle suffers from lower thermal efficiency, larger size, and inadequate cold source matching, failing to meet the demands for high efficiency, compactness, and adaptability required by new-generation underwater power plants. Consequently, the T-CO2 mixture power cycle has been proposed for technological innovation in underwater nuclear plants. Thermodynamic model of the recuperated, precompression, recompression and partial cooling cycles is developed based on the first law of thermodynamics. And the thermodynamic performance of five CO2 mixtures, including CO2/SO2, CO2/H2S, CO2/butane, CO2/propane, and CO2/cyclohexane in the four cycles coupled with a pressurized water reactor (PWR) and an advanced high-temperature reactor (AHTR) is investigated. The findings reveal that when optimized for thermal efficiency, the CO2/cyclohexane is better suited for recuperated and precompression cycles, while CO2/H2S and CO2/propane are more suitable for recompression and partial cooling cycle. Furthermore, regarding the T-CO2 mixture power cycle incorporating PWR and AHTR, the recompression cycle of CO2/propane and CO2/H2S should be opted to achieve maximum thermal efficiencies of 33.07 % and 46.07 %, respectively. Conversely, selecting the precompression cycle of CO2/H2S can yield maximum specific work of 98.61 kJ/kg and 161.62 kJ/kg, respectively. Therefore, investing in reforming nuclear power with new technologies is a feasible policy choice. Additionally, policymakers need to closely monitor the reform requirements of nuclear power plants.