Patent Number: 
Section: claims

1. A spent fuel dry reprocessing method for directly obtaining a zirconium alloy nuclear fuel, comprising the steps:a. determining components and a ratio for a molten salt composition used for melting a spent fuel according to a zirconium alloy fuel design requirement and contents of actinium series metals in the spent fuel, wherein the molten salt composition comprises zirconium fluoride, potassium fluoride and lithium fluoride, and wherein a mole ratio of zirconium fluoride to potassium fluoride to lithium fluoride is 1:(10-20):(25-80);b. melting the spent fuel in the molten salt composition; andc. forming a zirconium alloy comprising uranium, zirconium and plutonium with a composition according to said zirconium alloy fuel design requirement, wherein said zirconium is derived from said molten salt composition, and said zirconium alloy is formed by an under-potential deposition process on an electrode, thereby obtaining a zirconium alloy nuclear fuel through uranium-plutonium-zirconium co-electrodeposition on the electrode. 2. The spent fuel dry reprocessing method according to claim 1, wherein a mixture of the spent fuel and the molten salt composition is molten at 600-1050° C. 3. The spent fuel dry reprocessing method according to claim 1, wherein the molten spent fuel has excess metal ions, and a pre-electrodeposition process is carried out through a second electrode pair so the excess metal ions in the spent fuel are separated. 4. The spent fuel dry reprocessing method according to claim 3, wherein the spent fuel is a metal oxide spent fuel, a positive electrode of the second electrode pair used in the pre-electrodeposition process to separate out the excess metal ions and a positive electrode of the first electrode pair selected for the electrodeposition process to form the zirconium alloy nuclear fuel are made of inert material. 5. The spent fuel dry reprocessing method according to claim 3, wherein the spent fuel is a metal spent fuel, and a positive electrode of the second electrode pair used in the pre-electrodeposition process to separate out the excess metal ions is the metal spent fuel.