Safety analysis of a supercritical carbon dioxide cooled reactor system coupled with Brayton cycle under loss-of-coolant accident

Supercritical carbon dioxide (SCO2) Brayton cycle is considered as one of power conversion systems for small modular reactors (SMRs) due to its compact and simple layout. SCO2 Brayton cycle direct cooled reactor further reduces the number of system components and simplifies the system layout, which makes it suitable for the design of offshore floating nuclear power plant. In this paper, a conceptual design is proposed for 1MWe offshore floating nuclear power plant (SCFNP-1), applying SCO2 direct cooled reactor system. Considering that the design of mass flowrate for low-power system is small, pre-pressure safety containment is applied to ensure system safety under LOCA condition. Based on the safety system for SCFNP-1, its transient performance is analyzed through simulation according to the protection logic. The pre-pressure safety containment effectively limits the drop of system pressure and core mass flowrate, and it also reduces the leakage mass of SCO2. This work provides helpful references for the safety of low-power SCO2 direct cooled reactor systems with pre-pressure safety containment under LOCA.