Integrated small modular molten salt reactors and pre-compression supercritical carbon dioxide Brayton cycle for ship propulsion: preliminary system performance analysis and optimization

International shipping faces stringent decarbonization mandates, necessitating zero-emission propulsion systems. This study pioneers the integration of small modular molten salt reactors with pre-compression supercritical carbon dioxide (sCO2) Brayton cycles for zero-emission ship propulsion. Thermodynamic modeling demonstrates that the pre-compression configuration designed in this study can achieve 36.6% thermal efficiency at 640°C turbine inlet temperature while exhibiting critical operational advantages: 1) Enhanced stability against seawater temperature fluctuations (33–45°C), showing only 3.7% efficiency variation vs. 11.5% in recompression cycles. 2) Mitigated thermal stress of main heat exchanger via reduced the main compressor discharge pressure to 20 MPa. 3）Robust cold-side temperature control at the molten salt-sCO₂ heat exchanger inlet (variation <0.3%), preventing molten salt solidification below 454°C. These results resolve key maritime constraints— compactness, dynamic cold-sink resilience, and safety—establishing nuclear-powered propulsion as a technically viable pathway toward International Maritime Organization’s 2050 decarbonization targets.