KR20200091176A - Salt exchange type pyroprocessing method and system - Google Patents

Abstract

The present invention relates to a salt exchange type pyroprocessing method and system and, more particularly, to a pyroprocessing system capable of increasing efficiency of processing large amounts of spent nuclear fuel by simplifying a series of pyroprocessing processes through a salt exchange type process, and a pyroprocessing method using the same. According to the present invention, the pyroprocessing method or system uses fixed devices, unlike the conventional pyroprocessing concept in which the spent nuclear fuel moves through each process unit, and applies a method in which molten salt in a liquid state is sequentially charged into a reactor instead of the spent nuclear fuel. Therefore, mechanical operation is minimized and inter-process linkage is smoothly performed. Therefore, when the pyroprocessing is implemented in a larger size, efficiency of the process is increased, and the cost required for building, maintaining, and repairing equipment is reduced, thereby greatly contributing to the improvement of economic efficiency. In addition, efficiency of the entire process can be maximized through the establishment of a network-based process and process efficiency reduction can be minimized due to maintenance and repair.

Description

Salt exchange type pyroprocessing method and system {SALT EXCHANGE TYPE PYROPROCESSING METHOD AND SYSTEM}

The present invention relates to a salt exchange type pyroprocessing method and system, and more specifically, a pyroprocessing system capable of increasing the efficiency of processing large-capacity spent fuel by simplifying a series of pyroprocessing processes through a salt exchange method. And a pyroprocessing method using the same.

The nuclear fuel used for light reactors is difficult to handle due to its high radioactivity level and heat of decay, and permanent disposal technology has not yet been completed. The currently used spent fuel treatment method is a wet reprocessing technique, which dissolves the spent fuel in nitric acid and separates useful materials into a new fuel to be used in a light water reactor. However, because wet reprocessing technology can extract plutonium, latecomers to nuclear technology such as South Korea have limited access. Therefore, the proposed technology is a pyroprocessing process to solve the accumulated spent fuel problem. The pyroprocessing process is considered to have relatively high nuclear non-proliferation because it separates plutonium from uranium and other superuranium nuclides.

Pyroprocessing technology is largely pre-processing process to manufacture raw materials for disassembly and subsequent processes, electrolytic reduction process to convert oxide spent fuel into metal form, electrorefining process to separate uranium from spent fuel, uranium and superuranium (TRU) consists of an electrolytic smelting process for recovering nuclides, and includes processes for recovering waste from each process. However, this is a very simplified explanation, and in order to actually operate the pyroprocessing, various other processes, such as distillation and reloading of samples, are involved in the middle of each process. In particular, in order to perform the electrorefining process after the electrolytic reduction process, after the electrolytic reduction is completed, the spent fuel in the form of metal is distilled to remove residual salts, and then withdrawn from the basket and put again into the basket for electrorefining. In addition, during the electrolytic reduction process, salt-soluble nuclides Sr, Ba, Eu, etc. are dissolved as salts, and when Sr and Eu are accumulated in large quantities as high heat-dissipating nuclides, there is a fear of overheating of the process equipment. Therefore, a periodic purification process of the salt must be involved. These series of processes are disadvantageous for high-capacity and hot-cell operation because a large number of process equipment and mechanical movement systems are required.

Pyroprocessing technology development for the management of spent nuclear fuel, NEWS & INFORMATION FOR CHEMICAL ENGINEERS, Vol. 34, No. 3, 2016

The present invention provides a pyro-processing system and a pyro-processing method using the pyro-processing system capable of increasing the efficiency of processing a large amount of spent fuel by simplifying a series of pyro-processing processes through a salt exchange method.

The present invention, a universal reactor; A first system for reduction reaction, provided with a first reservoir; A second system for purging for cleaning, provided with a second reservoir; And a third storage, a third system for refining reaction, comprising a salt exchange type pyroprocessing system using a pyroprocessing system, after loading spent fuel into the universal reactor, the first reservoir Injecting the alkali metal-alkali metal salt, alkaline earth metal-alkali metal salt or a mixed salt thereof provided in the universal reactor to perform a reduction reaction of spent nuclear fuel (step a); After the reduction reaction, purging by supplying an alkali metal salt, an alkaline earth metal salt, or a mixed salt for the purge provided in the second reservoir to the universal reactor (step b); And then, to the universal reactor, the alkali metal salt, alkaline earth metal salts or eutectic salts provided in the third reservoir, and UCl ₃ , the electrode for the electrorefining reaction is charged to perform the electrorefining process (step c) Pyroprocessing method comprising a).

In addition, the present invention, a universal reactor in which reduction and refining reactions are performed; A first system for a reduction reaction is provided with a first reservoir for storing an alkali metal-alkali metal salt, an alkaline earth metal-alkaline metal salt or a mixed salt thereof supplied to the universal reactor; A second system for purging for cleaning, which is provided with a second reservoir in which an alkali metal salt for purge supplied to the universal reactor, an alkaline earth metal salt or a mixed salt thereof is stored; And a third system for a refining reaction provided with an alkali metal salt, an alkaline earth metal salt, or a eutectic salt thereof supplied to the universal reactor, and a third reservoir in which UCl ₃ is stored. do.

The pyroprocessing method or system according to the present invention uses stationary devices and uses a molten molten salt instead of spent fuel into the reactor sequentially, unlike conventional pyroprocessing concepts in which spent fuel moves each process unit. By applying the method, mechanical operation is minimized and linkage between processes is smoothly performed. Therefore, when the pyroprocessing is realized in a large scale, the efficiency of the process is increased, and the cost for constructing, maintaining, and repairing equipment is reduced, which can greatly contribute to the improvement of economic efficiency. In addition, it is possible to maximize the efficiency of the entire process through the construction of a network-type process and minimize the reduction in process efficiency due to maintenance and repair.

1 schematically illustrates a salt exchange type pyroprocessing process according to an embodiment of the present invention.
2 is a schematic diagram of a universal reactor according to an embodiment of the present invention.
3 is a schematic view of a universal reactor lid for an electrorefining reaction according to an embodiment of the present invention.
Figure 4 schematically shows the networking of a salt exchange type pyroprocessing process according to an embodiment of the present invention.

Hereinafter, the present invention will be described in more detail through examples. The objects, features, and advantages of the present invention will be readily understood through the following examples. The present invention is not limited to the embodiments described herein, but may be embodied in other forms. The embodiments introduced herein are provided to sufficiently convey the spirit of the present invention to those skilled in the art to which the present invention pertains. Therefore, the present invention should not be limited by the following examples.

The present invention is a universal reactor; A first system for reduction reaction, provided with a first reservoir; A second system for purging for cleaning, provided with a second reservoir; And a third storage, a third system for refining reaction, comprising a salt exchange type pyroprocessing system using a pyroprocessing system, after loading spent fuel into the universal reactor, the first reservoir Injecting the alkali metal-alkali metal salt, alkaline earth metal-alkali metal salt or a mixed salt thereof provided in the universal reactor to perform a reduction reaction of spent nuclear fuel (step a); After the reduction reaction, purging by supplying an alkali metal salt, an alkaline earth metal salt, or a mixed salt for the purge provided in the second reservoir to the universal reactor (step b); And then, to the universal reactor, the alkali metal salt, alkaline earth metal salts or eutectic salts provided in the third reservoir, and UCl ₃ , the electrode for the electrorefining reaction is charged to perform the electrorefining process (step c) Pyroprocessing method comprising a). The method can be carried out in a form in which spent fuel is alternately supplied with salts of the three systems while remaining in the universal reactor.

The alkali metal-alkali metal salt may include Li-LiCl, and the alkali earth metal-alkaline metal salt may include Ca-CaCl ₂ . In addition, the alkali metal salt may include LiCl, the alkaline earth metal salt may include CaCl ₂ , and the eutectic salt may include LiCl-KCl or LiCl-CaCl ₂ . In step a, the mixed salt may be operated in the form of Li-Ca-LiCl-CaCl ₂ .

The system proposed in the present invention includes three systems: a first system for a reduction reaction, a second system for purging for washing, and a third system for refining reaction, centering on a universal reactor in which reduction and refining reactions are performed. It plays its role in the surroundings. Contrary to the existing concept that spent fuel moves each device, in this system, spent fuel stays in the universal reactor and performs work while the salts of the three systems are alternately supplied, thereby minimizing mechanical movement and the overall process flow. This is simplified.

The present invention aims to increase capacity and improve process efficiency by eliminating the loading and transfer process of spent fuel, which is a disadvantage of existing batch-based process-based pyroprocessing. In the present invention, when the spent fuel is charged to the universal reactor, the molten salt necessary for the reaction is repeatedly performed charging/removing, and thus a series of processes are performed. Therefore, there is no process of transferring or reloading the spent fuel for each process. do. In the present invention, a reduction process in which an alkali metal-alkali metal salt, an alkaline earth metal-alkaline metal salt, or a mixed salt thereof (Li-LiCl, Ca-CaCl ₂ or a mixed salt thereof) is charged in a universal reactor; Washing process using an alkali metal salt, an alkaline earth metal salt, or a mixed salt thereof (LiCl, CaCl ₂ or a mixed salt thereof); And, alkali metal salts, alkaline earth metal salts or eutectic salts thereof (LiCl, LiCl-KCl eutectic salts, LiCl-CaCl ₂ eutectic salts, etc.), and UCl ₃ electrolytic refining process sequentially proceeds, each salt is a separate purification And cyclic cycles. Another advantage of the present invention is that it is possible to optimize process efficiency through networking and minimize losses due to maintenance.

Specifically, after the spent nuclear fuel is charged to the universal reactor, an alkali metal-alkali metal salt, an alkaline earth metal-alkaline metal salt, or a mixed salt thereof (Li-LiCl, Ca-CaCl ₂ or a mixture thereof) from the first reservoir When salt, etc.) enters the universal reactor, the spent nuclear fuel is converted to metal. Alkali metal-alkali metal salts, alkaline earth metal-alkaline metal salts or mixed salts thereof (Li-LiCl, Ca-CaCl _2, or mixed salts thereof) are suspended for the reaction after a certain amount of injection, or a fixed amount to increase the reduction reaction The alkali metal-alkali metal salt, alkaline earth metal-alkaline metal salt, or a mixed salt thereof (Li-LiCl, Ca-CaCl ₂ or a mixed salt thereof) may be continuously provided. In addition, since there is no electrochemical reaction during the reduction process, the universal reactor can simply carry out the reaction with a lid to suppress the volatilization of salt. The salt in which the reduction reaction was performed in step a may be recovered into the first reservoir.

The first system may include a first reservoir, a purification device, and an electrolysis device. The first reservoir serves as a temporary storage space for the salt. The purification device performs a function of separating the soluble nuclides dissolved in the salt after the reduction reaction, through which the nuclides such as Sr, Ba, and Eu are separated from the LiCl salt. Thereafter, in the electrolysis apparatus, electrolysis of a salt containing Li ₂ O, Li, LiCl, or the like is performed. The Li-LiCl salt or the like obtained through this is moved to the first reservoir until the next use and is waited.

After a salt such as Li-LiCl is recovered as the first reservoir, a pure alkali metal salt, an alkaline earth metal salt, or a mixed salt thereof (LiCl, CaCl ₂ or a mixed salt thereof) is injected into the universal reactor. This is a process for removing residual Li, Li ₂ O, salt soluble nuclides, etc. remaining in the reactor and spent nuclear fuel, and can be understood as a washing (purging) concept. After purging in step b, salt (LiCl, CaCl ₂ or a mixed salt thereof) may be recovered into the second reservoir.

The second system may include a second reservoir and a purification device.

Here, the second reservoir serves as a reservoir for the salt, and the salt is transferred to a distillation and purification device. The distillation process is a well-known process, and in this system, salts such as separated LiCl and CaCl ₂ are recovered using a difference in the volatilization temperature of each metal and salt. The salt, such as LiCl, is transferred to the second reservoir and waits until the next process.

The third system may include a third reservoir, an electrolytic smelting device, and a purification device. The salt subjected to the electrorefining process in step c may be recovered into a third reservoir.

Specifically, an alkali metal salt, an alkaline earth metal salt or a eutectic salt thereof (LiCl, LiCl-KCl eutectic salt or LiCl-CaCl ₂ eutectic salt, etc.) may be stored in the _third reservoir, and a certain amount of UCl ₃ for the electrorefining process It may be dissolved. When the circulating process of the purifying salt (LiCl, etc.) is completed, salts such as LiCl, LiCl-KCl eutectic salt, or LiCl-CaCl ₂ eutectic salt are introduced into the universal reactor, and further inflow is stopped after a certain amount is introduced. An electrode for an electrorefining reaction may be charged together with a salt such as LiCl, LiCl-KCl eutectic salt or LiCl-CaCl ₂ eutectic salt, and the electrode may be introduced while being connected to the reactor lid. Electrolytic refining can be performed by applying electricity to the spent fuel basket and the electrode, and U in the spent fuel can be selectively electrodeposited and separated. The anode electrode for electrorefining may be made of graphite, stainless steel or tungsten. After performing the electrorefining process, salts such as LiCl, LiCl-KCl eutectic salt or LiCl-CaCl ₂ eutectic salt may be recovered into the third reservoir. Afterwards, salts such as LiCl, LiCl-KCl eutectic salts or LiCl-CaCl ₂ eutectic salts can be transferred to an electrolytic smelting apparatus to perform an electrolytic smelting process, and the salts obtained through this are transferred to a third reservoir to the next process. Will wait.

In addition, the present invention, a universal reactor in which reduction and refining reactions are performed; A first system for a reduction reaction is provided with a first reservoir for storing an alkali metal-alkali metal salt, an alkaline earth metal-alkaline metal salt or a mixed salt thereof supplied to the universal reactor; A second system for purging for cleaning, which is provided with a second reservoir in which an alkali metal salt for purge supplied to the universal reactor, an alkaline earth metal salt or a mixed salt thereof is stored; And a third system for a refining reaction provided with an alkali metal salt, an alkaline earth metal salt, or a eutectic salt thereof supplied to the universal reactor, and a third reservoir in which UCl ₃ is stored. do. The first system comprises a first reservoir, a purification device and an electrolysis device, the second system comprises a second reservoir and a purification device, and the third system comprises a third reservoir and a purification device. It can be configured to include.

The alkali metal-alkali metal salt may include Li-LiCl, and the alkali earth metal-alkaline metal salt may include Ca-CaCl ₂ . In addition, the alkali metal salt may include LiCl, the alkaline earth metal salt may include CaCl ₂ , and the eutectic salt may include LiCl-KCl or LiCl-CaCl ₂ . The mixed salt stored in the first reservoir may be operated in the form of Li-Ca-LiCl-CaCl ₂ .

Hereinafter, the present invention will be described in more detail with reference to the drawings.

The system proposed in the present invention is a LiCl system for a reduction reaction (first system), a purifying LiCl system for cleaning (second system), smelting and smelting around a universal reactor in which reduction and refining reactions are performed. Three systems of the LiCl-KCl system for reaction (third system) play their role in the surroundings. 1 is a schematic diagram of the overall configuration. Contrary to the existing concept that spent fuel moves each device, in this system, spent fuel stays in the universal reactor and performs work while the salts of the three systems are alternately supplied, minimizing mechanical movement and the overall process flow. This is simplified. When spent fuel is charged to the universal reactor, the Li-LiCl molten salt in the first reservoir (Reservoir #1) is injected into the universal reactor to convert the spent fuel oxide to metal. At this time, the salt-soluble nuclides Sr, Ba, Eu, etc. are dissolved in the salt, and the salt that has undergone the reduction reaction is transferred to the first reservoir (Reservoir #1). Since the salt that has undergone the reduction reaction contains nuclides such as Li ₂ O, Sr, Ba, and Eu, it undergoes a purification process to separate it, and then decomposes Li ₂ O and LiCl through an electrolysis process to form a Li-LiCl salt. To convert. After the reduction reaction, the universal reactor is supplied with LiCl for purge stored in a second reservoir (Reservoir #2), to further remove Li ₂ O and salt soluble nuclides remaining in the reactor and spent fuel. LiCl for purge is returned to the second reservoir (Reservoir #2) and stored as a pure LiCl salt by removing soluble nuclides, Li ₂ O, Li, etc. through a purification process. In the universal reactor after purging, LiCl-KCl eutectic salt of the third reservoir (Reservoir #3) is introduced, and at this time, an electrode for electrorefining is loaded on the lid of the universal reactor for electrochemical reaction. When the electrorefining process is performed, uranium in the spent fuel is separated and deposited on the surface of the cathode electrode, which is separated and recovered. When the electrorefining process is completed, the U and TRU nuclides are dissolved in the salt, which is transferred to the third reservoir (Reservoir #3) and then subjected to U and TRU recovery through the electrorefining process. Since rare earth and precious metal nuclides remain in the salt after the electrolytic smelting process, LiCl-KCl eutectic salt is stored in the third reservoir (Reservoir #3) after removal through the LiCl-KCl purification process. When a series of processes are completed, some unreduced materials and precious metals remain in the basket of spent nuclear fuel loaded in the universal reactor, which is removed after a certain amount is accumulated. Details of each device are as follows.

-Universal reactor: Fig. 2 shows a schematic diagram of the universal reactor. The spent fuel basket in the center of the reactor is loaded with spent fuel in an oxide state. Thereafter, when the Li-LiCl molten salt flows from the first reservoir (Reservoir #1) into the universal reactor, the spent oxide fuel is converted into a metal form through the following chemical reaction.

UO ₂ + 4Li → U + 2Li ₂ O

At this time, the generated Li ₂ O is highly soluble in LiCl salt, so it is mostly soluble in LiCl, and salt-soluble nuclides Sr, Ba, Eu, etc. in spent fuel also dissolve in LiCl salt. The LiCl salt may be stopped for reaction after injecting a certain amount, or it may be operated by continuously supplying a certain amount of Li-LiCl salt to increase the reduction reaction rate. Since there is no electrochemical reaction during the reduction process, the universal reactor is simply operated with a lid to suppress salt volatilization. When the reduction reaction is completed, the salts in which Li ₂ O, Sr, Ba, Eu, etc. are dissolved are discharged to the outside of the reactor and moved back to the first reservoir (Reservoir #1).

A pure LiCl salt is injected from the second reservoir (Reservoir #2) into the universal reactor where the Li-LiCl salt has escaped. This is a process for removing residual Li, Li ₂ O, and salt-soluble nuclides remaining in the reactor and spent fuel, and can be understood as a washing (purging) concept. When purging is complete, the LiCl salt is recovered back into the second reservoir (Reservoir #2).

Finally, LiCl-KCl salt containing UCl ₃ is charged into the universal reactor from the third reservoir (Reservoir #3), and a cathode electrode (graphite, stainless steel, tungsten, etc.) for electrorefining is charged through the reactor lid. The shape of the charged electrode is shown in FIG. 3, and the electrodes surround the basket in the universal reactor. The electrolytic refining process is performed by applying electricity to the spent fuel basket serving as the anode and the electrode of the lid serving as the cathode, and U in the spent fuel is selectively electrodeposited and separated. When the electrorefining reaction is completed, U, TRU, and rare earth nuclides are dissolved in LiCl-KCl, which all go to the third reservoir (Reservoir #3) and undergo the next process.

-LiCl circulation system (first system): The LiCl circulation system used for the reduction reaction consists of a first reservoir (Reservoir #1), a purification system, and an electrolysis device. Reservoir is not a special function, but only serves as a temporary storage space for salt. The LiCl purification system performs a function of separating soluble nuclides dissolved in a salt after a reduction reaction, and thereby, nuclides such as Sr, Ba, and Eu are separated from LiCl. Thereafter, in the LiCl electrolysis apparatus, electrolysis of a salt containing Li ₂ O, Li, and LiCl is performed. At this time, the process can be performed using iron as the cathode and platinum or carbon as the anode. When platinum is used, only electrochemical decomposition of Li ₂ O occurs, whereas when using a carbon anode, electrolysis of LiCl and chemical reaction of Li ₂ O and Cl ₂ are accompanied. When platinum is used as an anode, since the generated gas contains only oxygen, the structure of the device and the process is advantageous, but due to the limitation of the applied voltage, the process time is long and the high price of the electrode itself is a disadvantage. On the other hand, when the carbon anode is used, it is inexpensive and has a fast process through high voltage application, but has a disadvantage of generating chlorine gas with high corrosion. The resulting Li-LiCl salt is transferred to storage (Reservoir #1) and waits until next use.

- cathode: Li ⁺ + e ^- → Li

- a positive electrode _{^{(electrochemical) 2Cl - → Cl 2 (g}} ) + 2e - / 2O 2- → O 2 (g) + 4e - / C + 2O 2- → CO 2 (g) + 4e -

(Chemical reaction) 2Li ₂ O + 2Cl ₂ (g) → 4LiCl + O ₂ (g)

-LiCl circulation system for purge (2nd system): LiCl containing Li ₂ O, Li, and soluble nuclides is introduced into the second reservoir (Reservoir #2) by circulating LiCl for purge to remove residues in the universal reactor do. The reservoir simply serves as a reservoir for salt, and the salt is transferred to a distillation and purification unit. The distillation process is a well-known process. In this system, Li is first removed at a low temperature, and then LiCl is volatilized at high temperature and vacuum to recover. Then, only soluble nuclides and Li ₂ O remain in the device to obtain pure LiCl, and the obtained LiCl moves to a second reservoir (Reservoir #2) and waits until the next process.

-LiCl-KCl circulation system (third system): LiCl-KCl eutectic salt is stored in the third reservoir (Reservoir #3), and a certain amount of UCl ₃ for electrolytic refining process is dissolved. Upon completion of the purge LiCl circulation process, the LiCl-KCl eutectic salt is introduced into the universal reactor, and after a certain amount is introduced, further inflow is stopped. When LiCl-KCl eutectic salt is introduced, an electrode for electrorefining reaction is charged through the lid of the universal reactor (see FIG. 3). After the eutectic salt and the electrode are loaded, an electric potential is applied between the basket of the universal reactor and the electrode connected to the lid to operate the electrode so that U is electrodeposited. When the operation is completed, the electrode is removed to recover the electrodeposited U in a separate space, and the LiCl-KCl eutectic salt in which U, TRU, and rare earth nuclides are dissolved moves to the third reservoir (Reservoir #3). Thereafter, the LiCl-KCl eutectic salt is transferred to the electrolytic smelting apparatus to recover U and TRU. The rare earth nuclides still remain in the LiCl-KCl eutectic salt, which is transferred to the LiCl-KCl purification apparatus and subjected to a zone-cooled purification process to separate the rare earth nuclides and obtain a pure LiCl-KCl eutectic salt. The eutectic salt thus obtained is moved back to the third reservoir (Reservoir #3) to wait for the next process.

Another advantage of this system is that multiple systems can be networked. 4 shows a process network for processing large-scale spent fuel. Since there is a difference in the speed at which each process is performed from the first storage (Reservoir #1) to the third storage (Reservoir #3), establishing a network of processes in this way not only improves the efficiency of the entire process, but also It is also advantageous for maintenance and repair. The reason is that the existing serial process stops the entire process if one device fails in the middle, but in a networked process, if there is a problem with one device or process, you can get help from another device that functions the same. to be. Therefore, there is an advantage that the operation efficiency of the entire process is maximized, which can reduce the operating cost.

Claims (11)

Universal reactor; A first system for reduction reaction, provided with a first reservoir; A second system for purging for cleaning, provided with a second reservoir; And a third system for refining reaction, equipped with a third reservoir, as a pyroprocessing method using a salt exchange type pyroprocessing system,
After loading the spent fuel into the universal reactor, the reduction reaction of the spent fuel is performed by injecting the alkali metal-alkali metal salt, alkaline earth metal-alkaline metal salt, or a mixed salt thereof provided in the first reservoir into the universal reactor. Step (step a);
After the reduction reaction, purging by supplying an alkali metal salt, an alkaline earth metal salt, or a mixed salt for the purge provided in the second reservoir to the universal reactor (step b); And
Subsequently, an electrolytic refining process is performed by charging the universal reactor with an alkali metal salt, an alkaline earth metal salt, or a eutectic salt thereof provided in the third reservoir, and UCl ₃ and an electrode for electrorefining reaction (step c). Pyroprocessing method comprising a.
The method according to claim 1,
In the above method, the spent fuel remains in the universal reactor, and the pyroprocessing method is characterized in that it is performed in a form in which salts of the three systems are alternately supplied.
The method according to claim 1,
The pyroprocessing method characterized in that the salt in which the reduction reaction was performed in step a is recovered into the first reservoir.
The method according to claim 1,
The first system comprises a first reservoir, a purification device, and an electrolysis device, characterized in that the pyroprocessing method.
The method according to claim 1,
After purging is performed in step b, the salt is recovered into a second reservoir.
The method according to claim 1,
The second system comprises a second reservoir and a purification device, characterized in that the pyroprocessing method.
The method according to claim 1,
The pyroprocessing method characterized in that the salt subjected to the electrorefining process in step c is recovered into a third reservoir.
The method according to claim 1,
The third system comprises a third reservoir, an electrolytic smelting device, and a purification device.
The method according to claim 1,
The alkali metal-alkali metal salt includes Li-LiCl,
The alkaline earth metal-alkaline earth metal salt includes Ca-CaCl ₂ ,
The alkali metal salt includes LiCl,
The alkaline earth metal salt includes CaCl ₂ ,
The eutectic salt is Pyroprocessing method characterized in that it comprises LiCl-KCl or LiCl-CaCl ₂ .
Universal reactor in which reduction and refining reactions are performed;
A first system for a reduction reaction is provided with a first reservoir for storing an alkali metal-alkali metal salt, an alkaline earth metal-alkaline metal salt or a mixed salt thereof supplied to the universal reactor;
A second system for purging for cleaning, which is provided with a second reservoir in which an alkali metal salt for purge supplied to the universal reactor, an alkaline earth metal salt or a mixed salt thereof is stored; And
A salt exchange type pyroprocessing system comprising a third system for refining reaction, which is provided with a third reservoir in which alkali metal salts, alkaline earth metal salts or eutectic salts thereof supplied to the universal reactor and UCl ₃ are stored.
The method according to claim 10,
The first system comprises a first reservoir, a purification device and an electrolysis device,
The second system comprises a second reservoir and a purification device,
The third system includes a third reservoir, an electrolytic smelting device, and a purification device.

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