Long-term monitoring of spent fuel stored in dry cask storage is currently achieved through the use of seals and surveillance. Muon tomography can provide direct imaging that may be useful in cases where what is known as Continuity of Knowledge (CoK) has been lost using the former methods. Over the past several years, a team from Los Alamos National Laboratory has been studying the use of muon scattering and stopping to examine spent fuel in dry cask storage. Data taken on a partially loaded Westinghouse MC-10 fuel cask have demonstrated that muon scattering radiography can detect missing fuel assemblies. A model, validated by this data, shows that tomographic reconstructions of the fuel can be obtained in relatively short exposures. Model fitting algorithms have been developed for dealing with datasets with limited angular that appear to work well. Here we show that muon tomography can provide a fingerprint of a loaded fuel cask, because of its sensitivity to both the density and atomic charge of the spent fuel, and that it is sensitive to many diversion scenarios. This article is part of the Theo Murphy meeting issue ‘Cosmic-ray muography’.