Current SFR design may face difficulty in public acceptance due to the potential risk from sodium-water reaction (SWR) when the current conventional steam Rankine cycle is utilized as a power conversion system for a sodium-cooled fast reactor (SFR). In order to eliminate SWR, the Supercritical CO2 (S-CO2) cycle has been proposed. Since S-CO2 cycle has relatively high efficiency under moderate turbine inlet temperature (450~750℃), there are many researches on the S-CO2 cycle. To determine which S-CO2 cycle provides the most benefit to SFR, previous research works investigated various layouts including recompression, double recompression, intercooling, reheating, and condensation cycle. Moreover, a comparative analysis of the simple Brayton, precompression, recompression, and partial cooling cycle for a nuclear reactor was conducted over a wide of turbine inlet temperatures from 500℃ to 850℃ as well. Although the cost of piping and piping related equipment approximately accounted for 7-8% of the total construction cost, very few research works considered pipe selection criteria for the S-CO2 cycle. As one of the most important parts of a power plant, this paper will discuss how to select a suitable pipe while considering overall power plant performance as well as thermal expansion issue of the piping for the S-CO2 power plant. A conceptual design work of a small modular reactor (SMR) type SFR will be provided as well.