Reprocessing is not a method of spent-fuel disposal but merely an intermediate step that may precede final disposal to save resources. Based on physical and economic factors, it may prove reasonable to directly dispose of spent-fuel assemblies according to their individual burnups, i.e., according to the quality of the residual materials they contain, either through direct final disposal or via reprocessing and recycling. Currently, higher burnups are making reprocessing impractical.
Even if spent fuel is to be disposed of directly, the German concept provides that it must be kept in interim storage for as long as 40 yr after discharge from the reactor before it is brought into a repository. During this period, economic aspects must be continuously considered to decide whether the residual materials in the fuel assemblies could be economically used under circumstances other than those prevailing at present.