Method for recovering metallic nuclear fuel materials from spent nuclear fuel and method for reprocessing spent nuclear fuel

Abstract

A spent oxide form nuclear fuel in a spent nuclear fuel assembly which has been taken out from a light water reactor is reacted with fluorine in fluorination treatment process and then separated into gaseous UF 6 and solid converted fluoride. The UF 6 is purified in UF 6 treatment Process. In electrolysis using fused fluoride process, the converted fluoride is dissolved into a fused fluoride salt (a mixture of LiF and BeF 2 ) filled into an electrolysis cell of an apparatus for electrolysis. A first electrode, which is an anode, and a second electrode, which is a cathode, are submerged into the fused fluoride. A mixture of the oxides Li 2 O and BeO are added to the fused fluoride. A metallic plutonium and a metallic uranium contained in the fused fluoride is deposited onto the second electrode by energizing of the first and second electrodes.

1 . A method for recovering metallic nuclear fuel materials from spent nuclear fuel, comprising steps of:
 generating nuclear fuel fluorides by reacting fluorine with spent oxide form nuclear fuel taken out from a nuclear reactor,   removing one part of fluorinated uranium from among said nuclear fuel fluorides,   dissolving the remaining nuclear fuel fluorides and oxides into fused fluoride, and   energizing a first electrode which is an anode and a second electrode which is a cathode, both of which were immersed into the fused fluoride, and depositing onto the second electrode a metallic nuclear fuel material dissolved in said fused fluoride.   
   
   
       2 . The method for recovering metallic nuclear fuel materials from spent nuclear fuel according to  claim 1 , wherein the oxide is an oxide having a cation contained in the fused fluoride. 
   
   
       3 . The method for recovering metallic nuclear fuel materials from spent nuclear fuel according to  claim 1 , wherein an electrode containing carbon is used as the first electrode. 
   
   
       4 . A method for reprocessing spent nuclear fuel, comprising steps of:
 generating nuclear fuel fluorides by reacting fluorine with used oxide form nuclear fuel taken out from a nuclear reactor,   removing one part of fluorinated uranium from among said nuclear fuel fluorides,   dissolving the remaining nuclear fuel fluorides and oxide into fused fluoride, and   energizing a first electrode which is an anode and a second electrode which is a cathode, both of which have been immersed into the fused fluoride, and depositing a metallic nuclear fuel material dissolved in the fused fluoride onto the second electrode, and purifying the metallic nuclear fuel material deposited onto the second electrode.   
   
   
       5 . The method for reprocessing spent nuclear fuel according to  claim 4 , wherein the oxide is an oxide having a cation contained in the fused fluoride. 
   
   
       6 . The method for reprocessing spent nuclear fuel according to  claim 4 , wherein the purification of the metallic nuclear fuel material is carried out by using a fused chloride electrolysis apparatus having an electrolysis cell filled with a fused chloride. 
   
   
       7 . The method for reprocessing spent nuclear fuel according to  claim 4 , wherein the purification of the metallic nuclear fuel material is carried out by,
 energizing the second electrode and a third electrode such that the second electrode becomes a cathode and the third electrode becomes an anode when the metallic nuclear fuel material deposited onto the second electrode is immersed into the fused fluoride, and the third electrode is immersed into the fused fluoride; and   depositing a plurality of materials used in the manufacture of metallic nuclear fuel, among materials contained in said metallic nuclear fuel materials, onto the third electrode.   
   
   
       8 . The method for reprocessing spent nuclear fuel according to  claim 4 ,
 Wherein when the metallic nuclear fuel material deposited onto the second electrode includes a first metallic material used in the manufacture of the metallic nuclear fuel and a second metallic material which less readily dissolves into the fused fluoride than the first metallic material and which is unnecessary for the manufacture of the metallic nuclear fuel, and the fused fluoride includes a third metallic material which more easily dissolves into the fused fluoride than the first metallic material, a third electrode is immersed into the fused fluoride with the metallic nuclear fuel material deposited onto the second electrode being immersed in the fused fluoride; and   the purification of the metallic nuclear, fuel material is carried out by generating between the second electrode and the third electrode an electric potential in which the first metallic material deposited onto the second electrode is dissolved into said fused fluoride, in which the second metallic nuclear material deposited onto the second electrode is not dissolved into said fused fluoride, in which the first metallic material dissolved in the fused fluoride deposits onto the third electrode, and in which the third metallic material does not deposit onto the third electrode the third metallic material.   
   
   
       9 . The method for reprocessing spent nuclear fuel according to  claims 4 , wherein an electrode containing carbon is used as the first electrode.