Spent nuclear fuel recovering method and device

The present invention provides a method of and a device for continuously recovering spent nuclear fuels in a drytype reprocessing device having a compact shape and not causing problems in view of criticality safety control. Namely, a recovery vessel has at least three reaction chambers each having an inclined bottom so that thickness of the stored fuels is not increased to criticality-causing level. Chloride support salts as a reaction medium are stored as molten salts in the recovery vessel. Spent fuel oxides are supplied from the uppermost reaction chamber. Radioactive metals in the oxides are successively reacted with reaction materials contained in the molten chloride salts to convert them into chlorides of radioactive metal containing oxychlorides at reaction chambers at upstream positions including the most upstream reaction chamber. Oxychlorides are put to molten salt electrolysis to deposit radioactive metal oxides on an electrodes and recovered in the reaction chambers at the intermediate positions. Metals remaining in the molten salts are oxidized and deposited by precipitation in downstream reaction chambers. The molten salts containing deposited materials are discharged and the deposition materials are filtered and separated at the lowermost reaction chamber. (I.S.)