Supercritical Carbon Dioxide turbomachinery design for water-cooled Small Modular Reactor application

• We described the concept of coupling the S-CO2 Brayton cycle to the water-cooled SMRs.
• We describe a turbomachinery design code called KAISD_TMD that can use real gases too.
• We suggest changes to the S-CO2 cycle layout with multiple-independent shafts.
• KAIST_TMD was used to design the turbomachinery of suggested layout.

The Supercritical Carbon Dioxide (S-CO2) Brayton cycle has been gaining attention due to its compactness and high efficiency at moderate turbine inlet temperature. Previous S-CO2 cycle research works in the field of nuclear engineering were focused on its application to the next generation reactor with higher turbine inlet temperature than the existing conventional water-cooled nuclear power plants. However, it was shown in authors’ previous paper that the advantages of the S-CO2 Brayton cycle can be also further applied to the water-cooled Small Modular Reactor (SMR) with a success, since SMR requires minimal overall footprint while retaining high performance. One of the major issues in the S-CO2 Brayton cycle is the selection and design of appropriate turbomachinery for the designed cycle. Because most of the nuclear industry uses incompressible working fluids or ideal gases in the turbomachinery, a more detailed examination of the design of the turbomachinery is required for a power system that uses S-CO2 as working fluid. This is because the S-CO2 Brayton cycle high efficiency is the result of the non-ideal variation of properties near the CO2 critical point. Thus, the major focus of this paper is to suggest the design of the turbomachinery necessary for the S-CO2 Brayton cycle coupled to water cooled SMRs. For this reason, a S-CO2 Brayton cycle turbomachinery design methodology was suggested and the suggested design methodology was first tested with the existing experimental data to verify its capability. After then, it was applied to the proposed reference system to demonstrate its capability and to provide fundamental information for the future design.