Heterogeneous reactor reprocessing problems are discussed primarily from the viewpoint of a central solvent extraction reprocessing station. The currently proposed fuels have been classified into types to minimize the number of processing schemes required. Primary emphasis is placed on a description of alternate methods for converting fuels to a nitric acid soluble form and the effects of radiation and inert alloy metals on the solvent extraction method. Head-end methods include acid dissolution, oxidation, hydrochlorination, chlorination, carburization, molten metal dissolution, and electrolytic dissolution. A new reprocessing method, the Hermex process, which uses mercury as the dissolving agent, is also presented. Schematic flowsheets for proposed methods are included.