ANSYS/Fluent Simulation Model Development for Forced Helium Dehydration Process

Abstract

This thesis describes the development and design of simulation model in “ANSYS FLUENT” for Spent Nuclear Fuel dehydration process by “Forced Helium Dehydration” [13] method [28]. The simulation model was developed using the computational fluid dynamics software “FLUENT” [28]. After defueling a nuclear reactor, the fuel rods are kept underwater. Later they are put into a transfer cask. The fuel rods have to be stored in dry condition for long term storage. “Forced helium dehydration” [13] process uses dry helium gas flow to remove water content from the transfer cask. The mass transfer occurs due to diffusion-advection and evaporation-boiling. There are several evaporation and boiling methods available built in “FLUENT” [28]. So, an optimized method was chosen which was used for simulation of mass transfer in the “Forced Helium Dehydration” [13] process. The method was verified in a two dimensional model, then applied to a three dimensional model. The spent nuclear fuel rods can be arranged in different arrays inside the canister. For our simulation, we used a 7 x 7 array of spent nuclear fuel rods.