[en] Due to the invaluable interest in small-scale nuclear power plants around the world, it has been proposed to pay sufficient attention to the design of appropriate equipment, which can make Ukraine with its great potential as a producer a supplier of such nuclear power plants. The work considers the method of thermal calculation of a one-through steam generator with a coil heating surface and superheating of steam. As a result of analysis and comparison of the results, formulas were selected for calculating six different conditions of heat transfer: lumbar flow around the coil package with coolant and five heat transfer sections during the movement of the working fluid in the tube. The results of calculating the heat transfer surface for a steam generator with a capacity of 45 MW are presented. The obtained results correlate well with the calculation data by the ASPEN-TECH computer code. (author)