Development of Transient Dynamics Code for a Helically-Coiled Steam Generator Analysis Using Multi-Node Moving Boundary Model

Due to its compact design, higher heat transfer efficiency, and ability to produce superheated steam , helical coil steam generators (HCSG) have become a popular option for use in small modular reactors. This research focuses on developing a multi-node moving boundary model for the transient calculation of these steam generators. The secondary side of an HCSG consists of subcooled, two-phase, and superheated regions. The developed model can accurately track the boundaries of these phases and allocate their proportional heat transfer coefficients accordingly. Additionally, each region is divided into multiple nodes for more increased accuracy. This approach eliminates the need for fine nodes and phase detection in each node during each time step, significantly reducing the computational cost of calculating of steam generator behavior. Python programming language was used for computationsin this study, which greatly improved the speed and efficiency of the calculations. Furthermore, a RELAP5 model for HCSG was developed in this research . The results obtained from the developed code were compared against with RELAP5 calculated parameters. Multiple scenarios involving changes feedwater in properties and primary flow to the steam generator were modeled. The simulated scenarios demonstrate that both codes show similar trends for variations in the parameters. The methodology presented in this study can be applied to model HCSG dynamics in future studies.