Development of a computer code, ONCESG, for the thermal-hydraulic design of a Once-Through Steam Generator

Development of the conceptual design of a 300 MWt integral reactor, SMART (System-integrated Modular Advanced ReacTor), for utilization in nuclear cogeneration plants has been completed at the Korea Atomic Energy Research Institute (KAERI). The major primary components of the SMART such as modular helical steam generators, main circulation pumps and a self regulating pressurizer are integrated into a reactor vessel. It is a common practice to employ a once-through steam generator in integral reactor designs because of its advantages in compactness and simplicity of the flow path arrangements. In this study, a thermal hydraulic design and performance analysis computer code for a once-through steam generator using helically coiled tubes, ONCESG, is developed. To benchmark the developed physical models and computer code, once-through steam generators developed by other designers are simulated and ONCESG calculated results are compared with the design data. The overall characteristics of heat transfer area, pressure and temperature distributions calculated by ONCESG showed general agreements with the published data and it is demonstrated that the ONCESG code can be utilized for diverse purposes, such as, sensitivity analyses and optimum thermal design of a once-through steam generator.