Comparison between detailed and homogenous modeling methods in the TN-32B spent nuclear fuel demo cask: Part I – storage conditions

Due to the complexity of modeling spent nuclear fuel casks and canisters, the homogenous method (i.e., modeling the fuel regions as porous blocks with effective properties) is often utilized to conduct computational fluid dynamics simulations. This method allows for reducing the computational effort required by the detailed modeling method. However, no comprehensive comparison between the homogenous and detailed methods in a full cask has been reported in the literature. In this Part I paper, a detailed model of the TN-32 B spent nuclear fuel cask with a detailed representation of the fuel assemblies is compared to a model that uses the homogenous method under storage conditions. The same input parameters and computational mesh are used in both models. Effective thermal conductivities and porous flow coefficients in the radial and axial directions are developed and applied to the homogenous model. Temperature and axial velocities obtained from the detailed and homogenous models are compared on a point-to-point basis within the fuel regions. The results indicate that the homogenous model accurately predicts temperatures relative to the detailed model, with the most notable differences observed at lower elevations within the fuel regions. 95 % of fuel region temperature data are within 2 °C between the models. Furthermore, temperatures at 63 locations obtained from both models are compared to data from the High Burnup Demonstration project and the results showed a difference ranging from −7 °C to +10 °C.