Effect of Loading Pattern on Thermal and Shielding Performance of a Spent Fuel Cask

Two key considerations that must be addressed in licensing spent fuel storage systems are peak cladding temperatures and surface dose rates. Generally, storage systems are approved for a uniform loading of a design basis fuel. This analytical study addresses the effect of non-uniform loading patterns on peak fuel temperatures and cask surface dose rates. Three radial power distributions are considered: uniform loading, hotter assemblies in the center of the cask, and hotter assemblies near the wall of the cask. This paper summarizes the results of an analytical study [1] in which it was shown that, for the same total heat load in a cask, peak fuel temperatures are reduced by loading hotter assemblies around the outside of the cask’s basket. It was also shown that loading the hotter assemblies around the outside of the cask results in modest increases in surface dose rates.