The extent to which actinides must be removed from spent reactor fuel in order to reduce the hazard index of high-level waste after a 1000-yr storage period to 5% of the hazard index of pitchblende has been determined, and a partial evaluation of the feasibility of accomplishing these removals has been made. The feasibility study was directed primarily at high-level waste from commercial reprocessing of light-water-reactor fuel. Conceptual processes were derived from published information. Several specific problems must be solved before satisfactory process flow sheets can be developed for obtaining the necessary degree of removal of uranium, neptunium, plutonium, americium, and curium.