The small modular reactor (SMR) technology has been receiving substantial attention, since it can minimize onsite construction work as well as reduce financial burden by reducing the total capital cost of a unit. The supercritical carbon dioxide (S-CO2) Brayton cycle can improve the SMR benefits further by having high efficiency from a compact power plant size. However, the high pressure operating condition (over 7.38MPa) and low viscosity of the fluid caused technical difficulties in designing appropriate seals and multi-stage turbo-machineries. To solve the problem in designing turbo-machineries, KAIST research team tested a Tesla turbine concept for the S-CO2 cycle application. The Tesla turbine is a friction disk type turbine, which uses fluid shear stress (friction force) to turn the disc. Because of the bladeless design, the Tesla turbine can be driven without any concerns of phase change in the fluid. To understand the main mechanism and losses, the KAIST research team tested a lab-scale Tesla turbine with the pre-existing KAIST S-CO2 experimental facility (S-CO2PE). This paper describes the preliminary experimental result of the Tesla turbine and the applicability to the small size S-CO2 cycle suitable for a SMR.