This paper presents the results of a techno-economic analysis of integrating a small modular supercritical CO2-cooled fast reactor (SMSC-GFR) with a high-temperature steam electrolysis unit for combined electricity and hydrogen production. Three power cycle confi-gurations are considered: subcritical Rankine, supercritical Rankine, and closed Brayton cycle using supercritical CO2. Thermodynamic modeling is performed in Aspen HYSYS, while the economic assessment employs a custom methodology that accounts for equipment modularity and learning effects. The Brayton cycle achieves the highest efficiency in both standalone (48.8%) and cogeneration (53.1% at 0.6 kg/s H2) modes. This cycle also exhibits the lowest power loss factor (0.36), providing a distinct advantage in system scalability. As the number of reactor modules increases from 1 to 10, the levelized cost of hydrogen decreases from $3.81 to $3.28 per kilogram. The findings confirm the viability of modular nuclear-hydrogen systems based on the SMSC-GFR and Brayton cycle, combining high thermodynamic performance, scalability, and economic competitiveness.