USOO7323153B2 (12) United States Patent (10) Patent No.: US 7,323,153 B2 Amamoto et al. (45) Date of Patent: Jan. 29, 2008 (54) REPROCESSING METHOD BY FLUORIDE 3,708,568 A * 1/1973 Golliher et al. ................ 423.6 VOLATILITY PROCESS USING 3.963.564 A * 6/1976 Lecocq ....................... 376/310 FRACTIONAL DISTILLATION 4,710,222 A * 12/1987 FitzPatrick et al. ........... 75,393 5,076,839 A * 12/1991 Boyd et al. ................... 75/631 (75) Inventors: Ippei Amamoto, Higashi-Ibaraki-gun 5,118,343 A * 6/1992 Coops ......................... 75/396 (JP); Koji Sato, Higashi-Ibaraki-gun 6,442,226 B1* 8/2002 Venneri et al. ............. 376/17O (JP) (73) Assignee: Japan Nuclear Cycle Development FOREIGN PATENT DOCUMENTS Institute, Ibaraki-Ken (JP) JP 2001-153991 6, 2001 (*) Notice: Subject to any disclaimer, the term of this RU 2108295 C1 * 4, 1998 patent is extended or adjusted under 35 U.S.C. 154(b) by 0 days. * cited by examiner (21)21) Appl. No.:No 11/097,2449 Primary Examiner Ngoc-Yen Nguyen (22) Filed: Apr. 4, 2005 (4) torney Agent, or Firm Wenderoth, Lind & Ponack, (65) Prior Publication Data (57) ABSTRACT US 2006/0057042 A1 Mar. 16, 2006 (30) Foreign Application Priority Data Fluorine or a fluorine compound is Subjected to a reaction with a spent oxide fuel to produce fluorides of uranium and Jul. 30, 2004 (JP) ............................. 2004-224444 plutonium, and recovering the fluorides using a difference in (51) Int. Cl volatility behavior. The method includes steps of subjecting opic io/44 (2006.01) a mixture of UO and PuO with hydrogen fluoride mixed CIG 43/6 (200 6. 01) with hydrogen to HF-fluorinate uranium and plutonium into UF and PuF; subjecting UF, and PuF with a fluorine gas COIG 56/00 (2006.01) tO F fluorinate uranium and plutonium into UF and PuF: (52) U.S. Cl. ................. 423 is: it. and 2fractionating UF, and PuF using a difference6 in phase6s 58) Field of Classification S s h s s 423 (3 change of obtained UF and PuF, removing a part of UF (58) Field of Classification Search .................... s and volatilizing the remaining UF, and PuF at the same 423/19, 489, 249, 251, 253, 258, 259 time. By Such a reprocessing method, PuF hard to undergo See application file for complete search history. a reaction is prevented from being formed as an intermediate (56) References Cited fluoride, the material of a reactor is hard to be corroded, and a consumption of expensive fluorine gas is reduced. U.S. PATENT DOCUMENTS 3,644,104 A * 2, 1972 Manevy et al. ................ 423.3 4 Claims, 3 Drawing Sheets Spent oxide fuel O2 - PuO2 Operating temp. 350-430°C HF supply: 1.1–1.3 times, HF fluorination step conc. 60-90 vol% HF-2 (fluidized bed furnace) H2 Supply: 1.1-1.3 times, conc. 10-30 wo% UF4 - PuF3 Operating temp. 500-750C Hz fluorination step F2 supply: 1. 1-1.3 times, (fluidized bed furnace) conc. 20-40 vol% Separation and volatilization step (cold traps) U.S. Patent Jan. 29, 2008 Sheet 1 of 3 US 7,323,153 B2 F.G. 1 Spent oxide fuel UO2 - Pu O2 Operating temp. 350-430°C HF supply: 1.1–1.3 times, HF fluorination step Conc. 60-90 vol% HF -- H2 (fluidized bed furnace) H2 Supply: 1.1-1.3 times, ConC. 1 O-3O vol% UF 4 - PuF3 Operating temp. 500-750C F H2 fluorination step F2 Supply: 1.1-1.3 times, 2 (fluidized bed furnace) Conc. 20-40 vol% UF6 - PuF6 Separation and volatilization step (cold traps) UF6 UF6 - PuF6 U.S. Patent Jan. 29, 2008 Sheet 2 of 3 US 7,323,153 B2 FIG.2 Spent oxide fuel (Main constituent elements: U.Pu,O,Zr, Nb, Mo, Tc, Ru,Sb,Te,Cs,Np,Am,Cm) UO2--PuO2 Operating temp. 400C HF fluorination HFHisty supply: 1.51.15 times,times, conc.conc. 3070 vol% vol% (fluidized bed furnace) ---> H2O UF4- PuF3 Operating temp. 500-750C F2 fluorination F2 supply: 1.15 times, (fluidized bed furnace) --> Alef, conc. 20-40 vol% UF6 - PuF6 Operating temp. -70 to OC Pressure 50 kPa Condensation of UFs PuFs --St. 2,TeF6, Operating temp. 53.1-56.5°C Pressure 83.633-83.686-KPa Separation of UF6/PuF6 Operating temp. 53-56.5°C Volatilization of UF6 PuF6 Pressure 50 kPa Cold traps Operating temp. 300C SSification SASof UF - - - - b. PuF6,CsF Operating temp. 120C (MgF2Purification traps) of UF6 b- RuFs,SbF5,NpF6NbF6, MoF6, TcF6, UF6--PuFa Operating temp. 300-400C NES of UF6 -----------> ZrF4, Rufs,NbF6 UFs "-taura of Pu enrichment Operating temp. -70 to OC Pressure 50 kPa Condensation of UF6Condensation of UFs-PuFs Operating temp. 70 to 80C Volatilization of UF6 Volatilization of UF6PuFs Pressure 50 kPa (cold traps) (cold traps) Filling in cylinder for UF6 | To MOX reconversion process To UO2 recorversion process U.S. Patent Jan. 29 2008 Sheet 3 of 3 US 7,323,153 B2 )© 91 9| 01 21 2Ond+2On US 7,323,153 B2 1. 2 REPROCESSING METHOD BY FLUORIDE there are disadvantages that temperature adjustment for VOLATILITY PROCESS USING conversion conditions of a target Substance is impossible, a FRACTIONAL DISTILLATION large amount of expensive fluorine gas is used, and so on. BACKGROUND OF THE INVENTION SUMMARY OF THE INVENTION 1. Field of the Invention Problems to be solved by the present invention are to The present invention relates to a method of separating establish a method for producing PuF in which PuF hard and purifying nuclear fuel Substances using a difference in to fluorinate further is prevented from being formed as an fluorination volatility behavior of uranium, plutonium and 10 intermediate fluoride, to establish a method for producing other elements in a spent oxide fuel to reprocess the spent PuF. in which the material of a reactor is harder to corrode, oxide fuel. to reduce a consumption of expensive fluorine gas, and so 2. Description of the Related Art O. A fluoride volatility process is one of methods for dry According to the present invention, there is provided a reprocessing of a spent fuel, in which nuclear fuel Sub 15 reprocessing method by a fluoride volatility process using stances such as uranium and plutonium and various kinds of fractional distillation in which fluorine or a fluorine com nuclear fission products are separated and recovered using a pound is Subjected to a reaction with a spent oxide fuel in difference in volatility behavior when they are fluorinated. two stages to produce fluorides of uranium and plutonium, Techniques for applying the fluoride volatility process to a and recover uranium and plutonium as the fluorides using a reprocessing process have been developed in the U.S. and difference in volatility behavior, the reprocessing method other various countries since 1950s. However, each of those comprising the steps of: techniques has problem in higher fluorination and purifica HF fluorination of the spent oxide fuel containing UO. tion of plutonium. None of these techniques has reached a and PuO in the reaction thereof with hydrogen fluoride practical phase, and there has been no progress since 1970s. mixed with hydrogen to produce UF and PuF as a first In Japan, Japan Atomic Energy Research Institute has 25 Stage, carried out the fluoride volatility process, and many advan F. fluorination of UF and PuF in the reaction thereof tages have been found, but development of the technique has with fluorine gas to produce UF and PuF as a second stage; been ended without establishing a plutonium purification and step. In the fluoride volatility process carried out in that separation and Volatilization of the resulting UF, and institute, uranium and plutonium are separated by two-stage 30 PuF, by fractionally distillating them (separating a gas and a fluorination using a fluidized bed furnace as a reactor with liquid) due to a difference in phase change therebetween to the temperature and fluorine concentration being changed. remove a part of UF as gas, and then volatilizing the For example, in the first stage, uranium is fluorinated with an remaining UF, and PuF at the same time. F concentration of 20% at the operating temperature of In the reprocessing method, the first stage HF fluorination 330° C., and in the second stage, plutonium is fluorinated 35 step is carried out preferably by Supplying a hydrogen with an F. concentration of 100% at the operating tempera fluoride gas containing 10 to 30 vol% of hydrogen using a ture of 330 to 550° C. fluidized bed furnace operated in the temperature range of However, there is a disadvantage that it takes much time 350 to 430°C., and the second stage F. fluorination step is to convert uranium into uranium hexafluoride (UF) because carried out preferably by Supplying a fluorine gas diluted to the reaction temperature in “fluorination of uranium’ of the 40 20 to 40 vol% using a fluidized bed furnace operated in the first stage is low, and that plutonium easily forms the most temperature range of 500 to 750° C. stable plutonium tetrafluoride (PuF). Further, in “fluorina The separation and volatilization step is carried out by tion of plutonium’ of the second stage, there is a disadvan using at least one cold trap, and the removal of the part of tage that plutonium is hard to be converted into plutonium UF is carried out by fractional distillation (gas-liquid sepa hexafluoride (PuF) (the conversion ratio or conversion rate 45 ration) at the operating temperature and pressure controlled decreases) from the point of view of thermodynamics and so that UF is in a gas region and PuF is in a liquid region reaction temperature because plutonium forms into PuF of in the phase diagrams of UF and PuF.