Enhancing hydraulic stability in once-through steam generators of small nuclear power plants: A novel approach using throttling baffles and feed pipes.

Given the increasing global interest in small nuclear power plants (SNPPs), the proposed research aims to investigate the design of once-through steam generators (OTSGs) used in SNPPs, with a particular focus on ensuring hydraulic stability in the heat exchange tubes. The study will examine the theoretical issues of ensuring stability and propose a new approach that includes the installation of throttling baffles and feed pipes to achieve hydraulic stability in OTSGs. The research will use a 45 MW capacity OTSG as an example, based on the design of the ship nuclear power plant KLT-40S, whose heat exchange surface (HES) is a set of coaxial cylindrical coils, similar to 60% of SNPPs with pressurized water reactors (PWRs). The rest of the SGs have either straight or U-shaped vertical heat exchange tubes (HET). The study will also explore the results of calculating the additional hydraulic resistance in front of the heat exchange tubes and propose a new method for clarifying the existing inequality used to ensure stability. Ultimately, the goal of this research is to provide a novel design for OTSGs based on throttling baffles and feed pipes to ensure hydraulic stability in SNPPs and provide new insights and methods for research in this field.