Abstract: A process for dissolving PuO.sub.2, NpO.sub.2, or fuel containing PuO.sub.2 and/or NpO.sub.2 in acid, particularly nitric acid by electrolytically continuously maintaining an oxidizing regenerable reagent. The regenerable reagent may be added to the mixture of oxide(s) and nitric acid. Alternately, it may already be present as a fission product or other nuclear reaction product in irradiated nuclear reactor fuel, in which case it need not be added to the nitric acid.

Abstract: An apparatus for continuously providing countercurrent liquid-solid contact. The preferred embodiment of the apparatus includes an Archimedes' screw in the form of a spiral and a distribution system which includes a central tube disposed along the axis of the spiral. The central tube includes a plurality of weirs and is in open communication with the spiral through a plurality of hollow spokes fixed at one end to the spiral and at the other end to the central tube.Dissolving solution is distributed by the distribution system to the spiral where it encounters nuclear material moving upward due to the pumping action of the spiral. The dissolved material moves counter current to the nuclear material and removed near the bottom of the apparatus.

Abstract: A method for removing volatile fission products from irradiated fuel which comprises passing a hydrogen-containing inert gas by said fuel which is at an elevated temperature of at least about 1000.degree. C. for a sufficient time to remove a significant portion of said fission products and a second step wherein inert gas alone is swept past the fuel while at said elevated temperature.

Abstract: The process for oxidizing irradiated fuel pellets using as the oxidant NO.sub.2 or a mixture of NO.sub.2 with its dissociation products, O.sub.2 and NO, in order to release the Volatile Fission Products (iodine, zenon, krypton and tritium) from the pellets.