Spent fuel storage: A reliable technology in the back end of fuel cycle

The fuel cycle costs for light water reactors and the demands in the nuclear fuel reload market suggest the need for increasing discharge burnups. Available fuel development efforts such as the use of new cladding tube materials will indeed allow this goal to be achieved. It is expedient from both technical and economic viewpoints to subject high burn-up assemblies to longer term interim storage before further treatment--reprocessing or final disposal--to make use of the natural decay of the activity inventory. Long-term interim storage tends to concentrate almost on dry storage facilities. The capability of LWR fuel assemblies to be safely placed in dry storage facilities has been investigated in the course of extensive R and D programs and proven in practice as well. The results obtained can be employed to derive the conditions under which these fuel assemblies can be safely stored over several decades. Various dry store concepts have been developed and realized, they have been put into use for small and medium-sized fuel inventories. For the storage of larger amounts of fuel Siemens has developed the SIEMENS FUELSTOR as a modular dry block store.