Optimization design method for nets in multi-stage filtration system of nuclear power plant

The cooling water intake systems of nuclear power plants are increasingly vulnerable to operational disruptions due to the intrusion of marine organisms. To ensure reliable and safe operation, effective multi-stage filtration systems are essential. In this study, we propose an integrated design methodology that combines a performance simulation model—with coupled discrete element method (DEM) and finite element method (FEM) simulations—and a multi-objective optimization framework for the filtration nets. A bidirectional EDEM-Fluent coupling approach is employed to capture the interaction between seawater flow, the flexible net structure, and discrete marine organisms. By analysing the effects of net aperture and water flow velocity on both the interception efficiency and pressure drop, a multi-objective optimization model is formulated with the interception rate and total system cost as competing objectives. The NSGA-II algorithm is then used to determine optimal design schemes, with convergence evaluated via the hypervolume index. In addition, a simulation platform is developed to visualize the filtration process and provide intuitive feedback for design evaluation. The results reveal a delicate balance between performance enhancement and economic feasibility, thereby offering essential theoretical and practical insights for the optimization of nuclear power plant filtration systems.