Investigating the dynamic possibilities of a nuclear sCO2 power conversion cycle for naval implementation

This study assesses the technical feasibility of nuclear propulsion for naval vessels by investigating the dynamics of a Very High Temperature Reactor combined with a supercritical carbon dioxide recompression cycle. By applying a dynamic model that includes the reactor, heat exchangers, and turbomachinery, the power dynamics of a nuclear energy conversion system are compared with those of common prime movers on a naval vessel. Results show that the turbine bypass valve, in combination with the dump cooler, enables a power ramp of 90%/min. During this power ramp, the reactor temperature stays within safety limits and experiences temperature variations of less than 25 degrees, the shaft speed remains stable with deviations of less than 0.25% RPM, and turbomachinery performs within design limits regarding temperature, pressure ratio and mass flow rate. However, the current turbine bypass valve design, which maintains a stable reactor output, results in a low overall cycle efficiency at part load. Furthermore, temperature- and pressure gradients of up to ±1.48 °C/s and ±0.38 bar/s occur within the heat exchangers during the power transient, which could affect the integrity of the materials. Further research could focus on a design that limits the thermal integrity concerns within the heat exchanger, and could implement energy storage capabilities to optimize the waste heat of the cycle during part-load.