Development of 3-D CFD methodology to investigate the transient thermal-hydraulic characteristics of coolant in a spent fuel pool

Based on the need for decommissioning and as a consequence of the Fukushima accident, research into spent fuel pools (SFPs) has become an important topic for nuclear safety analysis. In this paper, a three-dimensional (3-D) computational fluid dynamics (CFD) methodology is proposed to investigate the transient behaviors of flow and heat transfer for the coolant within a rod bundle in a SFP. A cell with a 17 × 17 rod bundle in a SFP of the Maanshan nuclear power plant (NPP) is practically simulated, instead of using the porous media assumption employed in previous simulations. Normal operation conditions are adopted in the present transient simulations. The thermal-hydraulic characteristics of coolant in a rod bundle can be reasonably captured by the present CFD model. These characteristics include the flow acceleration and heat transfer enhancement in the support grids, the secondary flow between the rods, and the non-uniform distributions of velocity and temperature on the cross-section of the rod bundle. In future, this 3-D transient CFD model can be extended to investigate accidents that might occur in the SFP. Such investigations can be useful in providing the transient characteristics of localized flow and heat transfer for the coolant to assist the tradition system codes in simulating the accident scenarios.