Numerical Investigation of Mist Flow Characteristics in a Hexagonal Fuel Rod Bundle

Reactor safety is one of the major concerns in nuclear power plants. The occurrence of critical heat flux (CHF) results in the sudden raise in the wall temperature. During the post-CHF conditions, the temperature of the fuel rods in the reactors can reach more than 1850 K. To maintain the temperature of the fuel rods under the permissible limit is essential to safeguard the structural integrity of the reactor fuel core. Therefore, the study of post-CHF regime plays a vital role in nuclear safety. In the present numerical study, numerical simulations were performed using the mixture model. For solving turbulence, RNG \(k -\epsilon\) model is employed. The model framework is validated against the experimental data and a good agreement was noticed. Further, the influence of critical quality and mass flux on the temperature, velocity and Nusselt number are also obtained. It is noticed that the fuel rod surface temperature is found to increase with increase in heat flux, decrease in mass flux, and increase in critical quality.