Thermo-Hydraulic Investigations of a Typical Small Modular PWR Using Computational Fluid Dynamics Modelling

Computational Fluid Dynamics (CFD) is widely used in different industrial applications. In this research, the application of CFD in the thermo-hydraulic evaluation for a typical small modular Pressurized Water Reactor (PWR) was studied using ANSYS Fluent software. First, reactor core with different (pitch—fuel rod diameter) was simulated using MCNP code. Subsequently, axial neutron heat flux was calculated in the hottest rod. In the following, different fuel channels were simulated using ANSYS workbench and corresponding mass flow rate according to the fluid outlet temperature was computed using Fluent. Then, thermo-hydraulic parameters including pumping power, convective heat transfer coefficient and turbulent intensity were calculated. Artificial neural network (ANN) coupled with genetic algorithm (GA) was used for optimization; and pair pitch ‒ fuel rod diameter (0.012 m, 0.0072 m) was selected as the optimum value. Also, Critical Heat Flux (CHF) was computed with CFD-simulation, and compared with Tong CHF correlation and Groeneveld look-up table. A good agreement was observed between results, but CHF obtained from CFD simulation was more conservative. According to the results, Minimum Departure from Nucleate Boiling Ratio (MDNBR) was obtained as 2.12, which was compatible with its typical value. Accordingly, it could be concluded that the optimum reactor core was in the safe mode in the steady state conditions.