We used computational analysis in order to study the cooling effects of the cylindrical tubes located inside a storage vault for spent nuclear fuel. We considered the effects of the radiative and convective heat transfer on the cooling of the cylindrical tubes based on the non-dimensional maximum permissible surface temperature. We also identified the factors that affect the cooling of cylindrical tubes by investigating the cooling effects with the same heat source as a function of the distance between the tubes, the entrance length, and the tube arrangement. The thermal performance, characteristics indicated that a non-uniform staggered tube array could be used in order to improve the storage efficiency of a vault in comparison to the reference uniform in-line tube arrangement, while maintaining the tube surface temperatures at a value below the maximum permissible temperature. (C) 2014 Elsevier Ltd. All rights reserved.