Nuclear Dry Cask Storage Container CFD Model Experimental Validation and Uncertainty Quantification

Abstract

CFD is a valuable tool for showing compliance with peak temperatures in dry cask storage systems (DCSS). When demonstrating compliance, it is valuable to quantify the uncertainty in the simulation result as a function of the computational mesh and simulation inputs. USNRC was a participant in a CFD validation test using the TN-32B cask, with extensive temperature measurements throughout the DCSS, including measurements on the cask surface and in fuel bundles. This paper discusses validation and uncertainty quantification of a CFD model using experimental data. Uncertainty quantification follows the procedures outlined in ASME V&V20-2009 [1]. Sources of uncertainty that were examined in the analysis include iterative uncertainty, spacial discretization, and uncertainty due to approximately twenty input parameters. Input parameters investigated include environmental conditions, material properties, decay heat, and the spacing of the many small gaps in the installation. The uncertainty in gap size was found to be a particularly large source of uncertainty in this particular installation. Results of a “base case” using the conservative estimates outlined in the updated final safety analysis report (UFSAR) [2] are presented, as well as a “best estimate case” that uses more realistic values. These results are compared to experimentally measured values, which fall within the uncertainty band of the analysis. This work is also the subject of an upcoming NUREG/CR.