[en] A significant number of pressurized water reactor (PWR) plants have reported decreases in their steam generator steam pressure during the last several years. Because a steam pressure decrease causes a reduction of the electrical power generating capacity directly, a steam generator's thermal performance is one of the important issues for steam generator maintenance. Therefore, the Korea Hydro and Nuclear Power Company has established an on-line acquisition system for plant operational parameters as a part of the Steam Generator Management Program (SGMP). Recently, plant-specific tools for calculating the overall heat transfer coefficient and the global fouling factor were also constructed and applied to some plants