JP4679070B2 - Method for reprocessing spent oxide fuel - Google Patents

Description

  The present invention relates to a method for reprocessing spent oxide fuel recovered from various nuclear reactors such as light water reactors and breeder reactors in nuclear power plants, and in particular, nuclear fuel such as uranium and plutonium in spent oxide fuel. The present invention relates to a method for reprocessing spent oxide fuel that separates substances from fission products and makes it possible to reuse recovered uranium as fuel.

  Spent nuclear fuel generated from nuclear power plants contains oxides of alkali metals, alkaline earth metals, rare earths and other fission products in addition to oxides of uranium and transuranium elements. It is reused as fuel through the treatment process.

  As one of dry reprocessing methods for processing spent nuclear fuel as it is at a high temperature, a molten salt electrolysis method is known. In this method, the inventor simultaneously dissolves the actinide oxide in the molten salt and performs electrolysis (simultaneous electrolysis method: anodic dissolution-simultaneous cathodic deposition method) to reduce the contamination of impurities such as noble metal elements and rare earth elements. The reprocessing method and apparatus which improved dyeing capacity and processing speed are proposed (for example, refer to patent documents 1).

  According to this method, uranium and plutonium can be recovered as oxides, and the processing speed can be increased as compared with the prior art.

By the way, in a breeder reactor, precious metals are likely to accumulate in fuel as compared with a light water reactor. Even in light water reactors, noble metals accumulate in the fuel if they are operated for a long time. Since uranium oxide and noble metal have similar deposition potentials during electrolysis, when the spent oxide fuel containing the noble metal is subjected to molten salt electrolysis, the recovered fuel is likely to contain the noble metal. In this regard, the inventor has proposed a reprocessing method and apparatus that increase the removal capability and processing speed to reduce the mixing of precious metal elements (see Patent Document 1).
Japanese Patent Laid-Open No. 9-90089 JP 2000-155193 A

Improved shown above, has played an improvement in process efficiency, in shear and decoating process, by cladding structure material is mixed in the fuel, the process efficiency of reprocessing is becoming clear that reduced It was.

  Since conventional shearing and decoating is based on a mechanical method, such a method inevitably introduces cladding chips into the spent fuel. In addition, since a part of the cladding tube component remains in the entire reprocessing process, the overall efficiency is reduced, which increases the reprocessing cost.

  For this reason, the separation process which can isolate | separate a cladding tube without mixing in the spent fuel of reprocessing object is desired.

  As described above, in the conventional shearing and decoating method, a part of the cladding tube is contained in the spent oxide fuel, and the process efficiency of the entire reprocessing is lowered. Therefore, it is desired to prevent the mixing of the cladding tube. ing.

  The present invention has been made in view of the above-described circumstances, and can prevent the fuel cladding tube from being mixed into the spent fuel in the decoating step in the reprocessing of the spent oxide fuel by molten salt electrolysis. An object of the present invention is to provide a method for reprocessing spent oxide fuel.

In order to achieve the above object, the present invention provides a spent oxide fuel reprocessing method for recovering nuclear material and fission products from spent oxide fuel and reusing the collected nuclear material. The fuel rod containing the spent oxide fuel is heated from 400 ° C. to 600 ° C. using carbon and chlorine and subjected to carbochlorination treatment, and the fuel rod components other than the spent oxide fuel are volatilized and removed. And a carbochlorination process for converting the spent oxide fuel from which the fuel rod components are volatilized and removed into chloride, and a chloride of the spent oxide fuel converted in the carbochlorination process. A charging step of charging and melting the molten salt, and electrolysis using a solid cathode immersed in the molten salt, and depositing noble metals contained in the spent oxide fuel on the surface of the solid cathode Chlorine gas and oxygen gas using a noble metal electrolysis removal step for recovering and removing the noble metal from the molten salt, and a solid cathode immersed in the molten salt after removing the noble metal in the noble metal electrolysis removal step And uranium electrolysis recovery step of electrolyzing while blowing a mixed gas of a gas and an inert gas, and depositing and collecting a part of uranium oxide contained in the spent oxide fuel on the surface of the solid cathode, and this uranium electrolysis recovery step Using the solid cathode immersed in the molten salt after removing the noble metal in step 1, electrolysis is performed while blowing a mixed gas of chlorine gas, oxygen gas and inert gas, and is contained in the spent oxide fuel. And a MOX electrolytic recovery step of depositing and recovering uranium oxide and plutonium oxide on the surface of the solid cathode.

  According to the present invention, by using chlorine and carbon, the cladding tube can be chlorinated and gasified, and volatile separation can be prevented, so that contamination into spent fuel can be prevented, and high purity uranium oxide and MOX (oxidation) can be prevented. Uranium and plutonium oxide mixture) can be efficiently recovered.

  Further, according to the present invention, regarding the reprocessing of spent nuclear fuel, uranium, plutonium and other nuclear fuel materials in the spent fuel generated from the nuclear power plant are separated from fission products and the recovered uranium is re-used as fuel. It is possible to reduce the contamination of the cladding tube into the spent oxide fuel that is the object of reprocessing, and to improve the efficiency of the reprocessing process.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1 is a process flow diagram illustrating a first embodiment of a spent oxide fuel reprocessing method according to the present invention, and FIG. 2 is a configuration diagram illustrating an apparatus used in the present embodiment.

As shown in FIG. 1, in the oxide fuel reprocessing method of this embodiment, the carbochlorination step (S101), the charging step (S102), the noble metal electrolysis removal step (S103), the uranium electrolysis recovery step (S104), and A MOX electrolysis recovery step (S105) is provided.

  In the carbochlorination step (S101), the fuel rod 1 including the spent oxide fuel 1a and the cladding tube 1b is subjected to carbochlorination treatment using a treatment gas 2 composed of chlorine 2a and carbon 2b, and used oxidation. The fuel rod components other than the physical fuel 1a are volatilized and removed, and the spent oxide fuel 1a is converted into chloride.

  FIG. 2 shows a carbochlorination processing apparatus used in this processing step. As shown in FIG. 2, the carbochlorination processing apparatus has a sealed container 4 provided with a heating coil 3. In this sealed container 4, chlorine gas 2 a and carbon (powder) 2 b are supplied from a chlorine gas supply unit 5 and a carbon (powder) supply unit 6 through supply pipes 7 and 8 and injection nozzles 9 and 10. It can be done.

  The sealed container 4 is provided with a reaction gas extraction port 11, and a condenser (trap) 14 is connected to the reactant extraction port 11 via a filter 12 and an extraction pipe 13. Thereby, the reaction gas produced | generated in the airtight container 4 is guide | induced to the condenser 14 through the filter 12, and is condensed.

  The carbochlorination process using this apparatus will be described in detail. First, the fuel rod 1 (used oxide fuel 1a + cladding tube 1b) is heated to 300 ° C. or higher in the sealed container 4. This heating action and the supply of chlorine 2a and carbon 2b cause a carbochlorination reaction, and the cladding tube 1b is chlorinated and used oxides as exemplified by the following chemical formulas (1) to (4). The oxide of each metal in the fuel 1a is deoxygenated and chlorinated to form a metal chloride.

[Chemical 1]
Fe + 3 / 2Cl ₂ → FeCl ₃ ↑
[Chemical 2]
Cr + 3 / 2Cl ₂ → CrCl ₃ ↑
[Chemical formula 3]
Ni + Cl ₂ → NiCl ₂ ↑
[Chemical formula 4]
Zr + 2Cl ₂ → ZrCl ₄ ↑
Here, the chloride of Fe, which is the main component of the constituent material of the cladding tube 1b, has a low vapor pressure and volatilizes at 300 ° C. or higher. Therefore, the cladding tube portion is volatilized and separated from the fuel portion that has become metal chloride. Is done. In this embodiment, it was confirmed that, for example, by heating to 400 to 600 ° C., Fe chloride and the like can be sufficiently volatile separated. If the heating temperature exceeds 600 ° C., chlorides of the following fuel substances will also volatilize, so the heating temperature is preferably set to 600 ° C. or lower.

  On the other hand, as illustrated in the following chemical formulas (5) to (7), the oxide is reduced by carbon and chlorinated.

[Chemical formula 5]
ZrO ₂ + C + 2Cl ₂ → ZrCl ₄ ↑ + C0 ₂
[Chemical 6]
UO ₂ + C + Cl ₂ → UCl ₄ + C0 ₂
[Chemical 7]
PuO ₂ + C + Cl ₂ → PuCl ₄ + C0 ₂
By such a carbochlorination step (S101), it is possible to volatilize and remove the fuel rod constituent material other than the used oxide fuel 1a and to convert the used oxide fuel 1a into chloride. Therefore, it is not necessary to cut the cladding tube 1b which has been conventionally performed, and it is possible to prevent cutting waste remaining due to the cutting of the cladding tube 1b in the prior art, and in a later process, the fuel coating It is possible to prevent the constituent material of the pipe 1b from being mixed into the spent fuel 1a. Accordingly, it is possible to reduce metal contamination in the spent oxide fuel 1a and improve the reprocessing process efficiency.

  In this step, carbon tetrachloride or organic gas can be used instead of chlorine + carbon.

Next, in the charging step (S102), the spent oxide fuel chlorides UCl ₄ and PuCl ₄ converted in the carbochlorination step (S101) are charged into the molten salt and dissolved. That is, after separating the cladding tube portion, it is put into a molten salt which is a halide such as sodium, potassium, cesium, rubidium or lithium, or a mixture of two or more of these, so that the introduced chloride is melted. Dissolve in.

  In the noble metal electrolysis removal step (S103), the solid electrode immersed in the molten salt is used as a cathode, and electrolysis is performed using this solid cathode. By this electrolysis, the noble metal 15 contained in the spent oxide fuel is preferentially deposited on the surface of the solid cathode, so that the noble metal 15 is precipitated and recovered by this action, and the noble metal is removed from the molten salt. Thereby, impurities are removed from the molten salt.

  Next, in the uranium electrolysis recovery step (S104), electrolysis is performed using the solid cathode immersed in the molten salt after the noble metal 15 is removed in the noble metal electrolysis removal step (S103), and the uranium electrolysis recovery step (S104) is included in the spent oxide fuel. Part of uranium oxide is deposited and recovered on the surface of the solid cathode. That is, in this uranium electrolysis recovery step (S104), melting is performed while blowing a mixed gas 16 of chlorine gas, oxygen gas and inert gas into the molten salt from which the noble metal 15 after the noble metal electrolysis removal step (S103) has been removed. By performing electrolysis using a solid electrode immersed in salt as a cathode, uranium oxide 17 is deposited on the cathode and collected. The recovered uranium oxide can be reused as nuclear fuel.

  In this uranium electrolysis recovery step (S104), the partial pressure of oxygen in the mixed gas 16 of chlorine gas, oxygen gas and inert gas is not oxidized to hexavalent but plutonium exists as tetravalent, and uranium exists. Only the partial pressure that oxidizes to hexavalent is set.

Finally, in the MOX electrolysis recovery step (S105), using the solid cathode immersed in the molten salt after removing the noble metal 15 in the uranium electrolysis recovery step (S104), chlorine gas, oxygen gas, and inert gas Electrolysis is performed while blowing the mixed gas, and uranium oxide and plutonium oxide contained in the spent oxide fuel are deposited and recovered on the surface of the solid cathode. That is, in the MOX electrolysis recovery step (S105), the solid electrode immersed in the molten salt in the molten salt after the uranium electrolysis recovery step (S104) is used as a cathode, and chlorine gas, oxygen gas, and inert gas are mixed. By performing electrolysis while blowing the mixed gas 16, a mixture (MOX) 18 of uranium oxide and plutonium oxide is deposited and collected on the cathode. The mixture of uranium oxide and plutonium oxide (MOX) 18 recovered in this step can be reused as nuclear fuel after the attached salt is removed.

  The oxygen partial pressure in the mixed gas of chlorine gas, oxygen gas, and inert gas is desirably set to a partial pressure at which plutonium is oxidized to hexavalent.

Moreover, the gas applied in the uranium electrolysis recovery process (S104) and the MOX electrolysis recovery process (S105) is not limited to the mixed gas 16 of chlorine gas, oxygen gas, and inert gas. For example, ClO2 can be used instead of chlorine gas and oxygen gas, and nitrogen gas can be used instead of inert gas.

  According to the first embodiment described above, it is possible to prevent cutting chips from remaining in the fuel cladding tube 1b, and to prevent the fuel cladding tube constituent material from being mixed into the spent fuel 1a. It is possible to reduce metal contamination and improve the efficiency of the reprocessing process.

[Second Embodiment]
FIG. 3 is a process flow diagram showing the second embodiment of the present invention.

  As shown in FIG. 3, in this embodiment, a chlorination decoating step (S201), a charging step (S202), a dissolving step (S203), a noble metal electrolysis removal step (S204), a uranium electrolysis recovery step (S205), and A MOX electrolysis recovery step (S206) is provided.

  First, in the chlorination decoating step (S201), fuel rod components other than the used oxide fuel of the fuel rod 1 including the used oxide fuel 1a are volatilized and removed with chlorine. That is, the fuel rod 1 (spent oxide fuel 1a + cladding tube 1b) is chlorinated by introducing chlorine 15 at a temperature of 300 ° C. or higher using an apparatus similar to the apparatus shown in FIG. 2 of the first embodiment. Cause a reaction.

  Thereby, the cladding tube 1b is chlorinated and becomes the same metal chloride as in the first embodiment. Here, as described above, the chloride of Fe, which is the main component of the cladding tube constituent material, has a low vapor pressure and volatilizes at 300 ° C. or higher. To be separated.

  In the chlorination decoating step (S201) of this embodiment, except for the carbon supply, substantially the same operation as the chlorine supply and reaction in the carbochlorination step (S101) in the first embodiment is performed. Therefore, for the common items, the first embodiment is referred to, and redundant description is omitted.

  Next, in the charging step (S202), the spent oxide fuel 1a processed in the chlorination decoating step (S201) is charged into the molten salt. That is, after the cladding tube 1b portion is separated in the chlorination decoating step (S201), it is put into a molten salt which is a halide such as sodium, potassium, cesium, rubidium or lithium, or a mixture of two or more thereof.

  In the melting step (S203), the used spent oxide fuel 1a is dissolved in the molten salt. That is, the used spent oxide fuel 1a is converted into chloride or acid chloride chemically or electrochemically with a halogen gas such as chlorine 2a, and is completely dissolved in the molten salt.

Next, in the noble metal electrolysis removal step (S204), electrolysis is performed at a low current density using a solid cathode immersed in a molten salt, and the noble metal and some uranium oxide contained in the spent oxide fuel 1a are solid cathode. The noble metal is removed from the molten salt by depositing and collecting on the surface. That is, a solid electrode immersed in a molten salt is used as a cathode, and electrolysis is performed at a current density lower than a limit diffusion current density value i _NM used for electrolytic deposition of the noble metal, so that the noble metal and some uranium oxide are reduced. The collected precipitate 19 is collected.

Here, the limit current density value i _NM used in the electrolytic deposition of the noble metal can be expressed as the following formula (1), and i _NM is determined by measuring D _NM , C _NM, and δ _NM. can do.

D _NM : Diffusion coefficient of noble metal ions in molten salt C _NM : Concentration of noble metal ions dissolved in molten salt (bulk concentration)
F: Faraday constant δ _NM : Diffusion layer thickness of noble metal ions in molten salt

  Next, in the uranium electrolysis recovery step (S205), electrolysis is performed using the solid cathode immersed in the molten salt after the noble metal is removed in the noble metal electrolysis removal step (S204), and the one contained in the spent oxide fuel 1a. Part of uranium oxide 17 is deposited and recovered on the surface of the solid cathode. That is, by performing electrolysis using the solid electrode immersed in the molten salt from which the noble metal has been removed after the noble metal electrolysis removal process as a cathode, high-purity uranium oxide 17 is deposited and recovered on the cathode. The recovered uranium oxide 17 can be reused as nuclear fuel after removing attached salt.

  Further, in the MOX electrolysis recovery step (S206), chlorine gas, oxygen gas, and inert gas are obtained using a solid cathode immersed in a molten salt after a part of uranium oxide is recovered in the uranium electrolysis recovery step (S205). Then, the uranium oxide and the plutonium oxide contained in the spent oxide fuel 1a are deposited and recovered on the surface of the solid cathode.

That is, in the MOX electrolysis recovery step (S206), the molten salt after the uranium electrolysis recovery step (S205) is immersed in the molten salt while blowing a mixed gas 8 of chlorine gas, oxygen gas and inert gas. by the solid electrode performing electrolysis as the cathode and the a uranium oxide and plutonium oxide (MOX) 18 you deposit collected on the cathode.

  The recovered uranium oxide and plutonium oxide (MOX) 18 can be reused as nuclear fuel after the attached salt is removed.

  Here, the oxygen partial pressure in the mixed gas 16 of chlorine gas, oxygen gas, and inert gas is set to a partial pressure at which plutonium is oxidized to hexavalent.

In this embodiment, the mixed gas 16 of chlorine gas, oxygen gas and inert gas is applied, but ClO ₂ is applied instead of chlorine gas and oxygen gas, and nitrogen gas is applied instead of the inert gas. can do.

  Also according to the second embodiment described above, it is possible to prevent cutting chips from remaining in the fuel cladding tube 1b and prevent the fuel cladding tube constituent material from being mixed into the spent fuel 1a. It is possible to reduce metal contamination and improve the efficiency of the reprocessing process.

[Third Embodiment]
FIG. 4 is a process flow diagram showing a third embodiment of the present invention.

  As shown in FIG. 4, in this embodiment, a chlorination decoating step (S301), a charging step (S302), a bath adjustment step (S303), an anodic dissolution-cathode deposition step (simultaneous electrolysis step) (S304), A dissolution step (S305), a noble metal electrolysis removal step (S306), and a MOX electrolysis recovery step (S307) are provided.

  Since the processing of the chlorination decoating step (S301) and the charging step (S302) is the same as the chlorination decoating step (S201) and the charging step (S202) of the second embodiment, the description thereof is omitted.

  In the bath adjustment step (S303), the bath is adjusted by dissolving uranium oxide in the molten salt. That is, uranium oxide or uranyl chloride is added and dissolved in the molten salt as uranyl chloride with a halogen gas such as chlorine 2a.

  Next, in the anodic dissolution-cathode deposition step (simultaneous electrolysis step) (S304), the spent oxide fuel is used as an anode, and the oxide fuel is dissolved in the molten salt using a solid cathode immersed in the molten salt. Part of uranium oxide contained in the oxide fuel is deposited on the surface of the solid cathode by electrolysis. That is, in this step, electrolysis is performed using the spent oxide fuel itself as the anode and the solid electrode immersed in the molten salt as the cathode. As a result, uranium oxide in the spent oxide fuel is dissolved in the molten salt, and high-purity uranium oxide 17 is deposited and recovered on the cathode. The recovered uranium oxide 17 can be reused as nuclear fuel after removing attached salt.

  After the recovery of uranium oxide, in the melting step (S305), the electrolysis is interrupted when the noble metal contained in the oxide fuel starts to dissolve, and the oxide fuel remaining in the molten salt is dissolved again. In other words, the spent oxide fuel that has been dissolved in the precious metal in the simultaneous electrolysis step (S304) is dissolved as a chloride or acid chloride in halogen gas such as chlorine gas or electrochemically in molten salt. To do.

Next, in the noble metal electrolysis removal step (S306), electrolysis is performed with the solid electrode immersed in the salt after the dissolution step (S305), and the noble metal contained in the oxide fuel is precipitated and collected on the surface of the solid cathode, so that the molten salt contains Remove noble metals from That is, as in the noble metal electrolysis removal step (S204) of the second embodiment, the solid cathode immersed in the molten salt is electrolyzed at a low current density, and the noble metal contained in the spent oxide fuel 1a is converted into the solid cathode. Precipitate and collect on the surface to remove noble metals from the molten salt. That is, the solid electrode immersed in the molten salt is used as the cathode, and the electrolysis is performed at a current density lower than the limit diffusion current density value i _NM used in the electrolytic deposition of the noble metal, thereby depositing the noble metal 15 with high separation efficiency. It can be recovered.

  Finally, in the MOX electrolysis recovery step (S307), mixing of chlorine gas, oxygen gas and inert gas using the solid cathode immersed in the molten salt after removing the noble metal in the noble metal electrolysis removal step Electrolysis is performed while blowing gas, and uranium oxide and plutonium oxide contained in the spent oxide fuel are deposited and recovered on the surface of the solid cathode. In other words, in the molten salt after the uranium electrolysis recovery step, the solid electrode immersed in the molten salt is used as a cathode, and electrolysis is performed while blowing a mixed gas 16 of chlorine gas, oxygen gas, and inert gas, thereby oxidizing. Uranium and plutonium oxide (MOX) 18 are deposited and collected on the cathode. The recovered uranium oxide and plutonium oxide (MOX) 18 can be reused as nuclear fuel after the attached salt is removed.

  In this MOX electrolysis recovery step (S307), the oxygen partial pressure in the mixed gas 16 of chlorine gas, oxygen gas, and inert gas is set to a partial pressure at which plutonium is oxidized to hexavalent.

In this embodiment, the mixed gas 16 of chlorine gas, oxygen gas and inert gas is applied, but ClO ₂ is applied instead of chlorine gas and oxygen gas, and nitrogen gas is applied instead of inert gas. can do.

  Also according to the third embodiment described above, it is possible to prevent cutting chips from remaining in the fuel cladding tube 1b and prevent the fuel cladding tube constituent material from being mixed into the spent fuel 1a. It is possible to reduce metal contamination and improve the efficiency of the reprocessing process.

[Fourth Embodiment]
In this embodiment, the hydrogen gas generated in the carbochlorination process or the chlorination decoating process is oxidized and recovered as water containing tritium. In this case, as a step of recovering hydrogen gas as water, it is desirable to pass it over a catalyst surface such as platinum.

  Specifically, in order to simulate tritium generated during processing and storage of metal waste such as hull, hydrogen gas was introduced into the system as a carrier gas (introduction gas) (4% hydrogen-96% air). When this gas was heated to 250 ° C. and passed through combustion filled with a platinum catalyst and oxidized to water, 99.9% or more of hydrogen could be recovered.

[Fifth Embodiment]
In this embodiment, in order to simulate the gas generated during the processing and storage of metal waste such as hull, the hull waste simulated product obtained by treating the actual fuel cladding tube with heated nitric acid is heated and compressed, and 2 standard gases are used as off-gas. % Introduced. When this gas was heated to 250 ° C., passed through a combustion tube filled with a platinum catalyst, oxidized to water and then passed through a cooling trap, the generated tritium gas of 99.9% or more was converted into tritium water into the cooling trap. It was possible to recover.

[Sixth Embodiment]
In this embodiment, the gaseous organic carbon compound generated in the carbochlorination process or chlorination decoating process is oxidized and recovered as carbon dioxide. Moreover, it is desirable to use an alkali scrubber as a method for recovering carbon dioxide.

  Specifically, the carbon dioxide gas treated by the third embodiment was passed through a granular copper oxide column heated to 650 ° C. and oxidized to carbon dioxide. Thereafter, a washing bottle containing 250 ml of 10N aqueous sodium hydroxide solution was passed (alkaline scrubber), and C-14 (volatile organic carbon compound) in the solution was measured. As a result, it was confirmed that almost all of the C-14 released into the gas system was recovered in the liquid collection.

The process flow figure showing a 1st embodiment of the used oxide fuel reprocessing method concerning the present invention. The block diagram which shows the apparatus used in 1st Embodiment of the spent oxide fuel reprocessing method which concerns on this invention. The process flow figure showing a 2nd embodiment of the used oxide fuel reprocessing method concerning the present invention. The process flow figure showing a 3rd embodiment of the used oxide fuel reprocessing method concerning the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fuel rod 1a Used oxide fuel 1b Cladding tube 2 Process gas 2a Chlorine 2b Carbon 3 Heating coil 4 Sealed container 5 Chlorine gas supply part 6 Carbon (powder) supply part 7, 8 Supply piping 9, 10 Injection nozzle 11 Reaction Gas extraction port 12 Filter 13 Extraction pipe 14 Condenser (trap)
15 Precious metal (NM)
16 Mixed gas (chlorine + oxygen + inert gas)
17 Uranium oxide (UO ₂ )
18 MOX (UO ₂ + PuO ₂ )
19 Recovered precipitate containing uranium oxide (UO ₂ + NM)

Claims (8)

In a spent oxide fuel reprocessing method for recovering nuclear material and fission products from spent oxide fuel and reusing the collected nuclear material,
The fuel rod containing the spent oxide fuel is heated from 400 ° C. to 600 ° C. using carbon and chlorine and subjected to carbochlorination treatment, and the fuel rod components other than the spent oxide fuel are volatilized and removed. And a carbochlorination step for converting the spent oxide fuel obtained by volatilizing and removing the fuel rod constituent material into chloride,
A charging step in which the spent oxide fuel chloride converted in this carbochlorination step is charged into molten salt and dissolved;
Electrolysis using a solid cathode immersed in the molten salt, precious metal contained in the spent oxide fuel is deposited and recovered on the surface of the solid cathode to remove the noble metal from the molten salt by electrolytic removal Process,
Using the solid cathode immersed in the molten salt after removing the noble metal in this noble metal electrolysis removal step, electrolysis is performed while blowing a mixed gas of chlorine gas, oxygen gas and inert gas, and the used oxide A uranium electrolytic recovery step for depositing and recovering a portion of uranium oxide contained in the fuel on the surface of the solid cathode;
Using the solid cathode immersed in the molten salt after removing the noble metal in the uranium electrolysis recovery step, electrolysis while blowing a mixed gas of chlorine gas, oxygen gas and inert gas, the used oxidation MOX electrolytic recovery step of depositing and recovering uranium oxide and plutonium oxide contained in the physical fuel on the surface of the solid cathode;
A spent oxide fuel reprocessing method characterized by comprising: The spent oxide fuel reprocessing method according to claim 1, wherein carbon tetrachloride is used in place of chlorine and carbon used in the carbochlorination step. Wherein instead of chlorine and oxygen used in the uranium electrolytic recovery process and MOX electrolytic recovery step, the spent oxide fuel reprocessing method according to claim 1, wherein the use of ClO _2. Wherein instead of the inert gas used in uranium electrolytic recovery process and MOX electrolytic recovery step, the spent oxide fuel reprocessing method according to claim 1, wherein the nitrogen gas is used. The car I Lori destination process or by oxidizing the hydrogen chloride gas generated in the de-coating process, the spent oxide fuel reprocessing method according to claim 1 wherein the recovered as water. The spent oxide fuel reprocessing method according to claim 5, wherein the hydrogen gas is recovered as water by passing it over a catalyst surface such as platinum. The car I Lori Nation step or chlorinated decoating process gaseous organic carbon compounds generated in oxidized spent oxide fuel reprocessing method according to claim 1 wherein the recovered as carbon dioxide. Wherein as a car I Lori destination process or method of recovering carbon dioxide generated in the chlorination decoating process, spent oxide fuel reprocessing method according to claim 1, wherein an alkali scrubber.

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