Civilian nuclear operations entail the transportation of sometimes substantial quantities of radioactive material. These can range from large quantities of weakly radioactive fresh fuel for power reactors, with the corresponding removal of highly radioactive spent fuel and operational wastes, to the shipment of small quantities of radioactive isotopes (“sources”) for medical, industrial or research purposes and their subsequent disposal. In relation to the civilian nuclear fuel cycle, there may also be relatively large quantities of radioactive material produced by “back-end” activities, such as the reprocessing of spent fuel to recover plutonium and then create mixed oxide, or MOX, fuel.1 In between these extremes, there are occasional consignments of fresh and spent fuel to and from research reactors, together with the associated wastes. In many of these cases, circumstances will dictate that consignments are dispatched overland, or by air, but there are some cases where a substantial maritime component is entailed and where there will be particular security and safety concerns that arise from that. Traditionally, the focus of this concern has been on the possibility of accidents, which might result in environmental contamination or human harm, but more recently, and certainly since 11 September 2001, the locus of concern has somewhat shifted to risks that might arise from the activities of non-state armed groups, or terrorists (or even pirates). This is the focus of the present review.