JP3504595B2 - Pretreatment method and pretreatment device for spent nuclear fuel - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a reprocessing plant for recovering uranium, plutonium, etc. from spent nuclear fuel in a fast reactor or a fast breeder reactor. The present invention relates to a pretreatment method of shearing and dissolving in a nitric acid solution or a molten salt, and an improvement of a pretreatment apparatus for carrying out this method.

[0002]

2. Description of the Related Art A nuclear fuel (hereinafter simply referred to as "fuel") used in a fast reactor or a fast breeder reactor is formed by forming a fuel material into a pellet shape, which is then formed into an austenitic stainless steel cladding tube (having a diameter of about 6 mm). (Cylindrical tube) to be a fuel rod, and a space wire for appropriately providing a space between the fuel rods is wound around the outer periphery of the cladding tube, and then a plurality of fuel rods are bundled into a fuel assembly to be loaded into the reactor. Burned in the furnace.

From the burned spent fuel, unburned uranium and plutonium are extracted by reprocessing to produce new fuel rods. In this reprocessing, the step of shearing the spent fuel rod and dissolving it in the nitric acid solution or the molten salt is called pretreatment.

In the conventional wet pretreatment which dissolves in nitric acid, a spent fuel rod is sheared (chopped) into a length of about 3 cm by a shearing machine, and is melted via an inclined pipe provided under the shearing machine. Nitric acid is dissolved (reach) in the tank. A sheared spent fuel rod is called a hull. The spent fuel contained in the hull is dissolved in nitric acid from the shear cut surface of the hull in the dissolution tank, resulting in an insoluble fission product (insoluble residue). To form a nitric acid solution containing slurry in the form of a slurry. Further, the shear metal pieces such as the hull and the space wire are not dissolved in nitric acid and remain in the dissolution tank, so that they are separately taken out from the dissolution tank. The nitric acid solution is separated into uranium and plutonium after separating and removing the insoluble residue in a later step. In addition, sheared metal pieces such as hulls and space wires are collected in hull cans as solid waste.

In the conventional dry pretreatment of dissolving in a molten salt, a spent fuel rod is supplied to a molten salt electrolytic cell after the cladding tube is cut open and only the spent fuel in the tube is taken out and crushed. Further, a pretreatment method has also been proposed in which spent fuel is oxidized together with a cladding tube at a high temperature, and the fuel is naturally pulverized by thermal expansion or the like. The spent fuel crushed in this way is
It becomes a molten salt solution that dissolves in the molten salt in the electrolytic cell and contains insoluble fission products (insoluble residue) in the form of a slurry. In addition, the cladding tube is collected in a hull as solid waste.

[0006]

In the conventional wet pretreatment method, since the spent fuel is sheared to a length of about 3 cm for each fuel assembly, it is necessary to place the fuel assembly horizontally in the shearing machine. The result was that the installation space for the shearing machine became large.

Further, in the dissolution tank, only the shear cut surface of the hull comes into contact with nitric acid, and the spent fuel gradually dissolves from both end surfaces of the shear, so that all the spent fuel is dissolved in nitric acid. It took several hours. This has led to an increase in the size of the melting tank, which has caused a rise in equipment manufacturing costs.

Further, the granular or powdery sheared metal powder (several tens of μm to several mm) generated at the time of shearing is carried as a slurry to the dissolution liquid in the same manner as the undissolved residue and is transferred to the subsequent step. Since the particle size is larger than that of the dissolution residue (several μm), not only is it easy to deposit in the middle equipment and piping, but also easily inside the dissolution tank. Such shear metal powder deposits are difficult to remove from the melting tank,
As a result, the melting tank itself, the equipment structure after the melting tank, and the operating method are complicated, which causes a rise in operating costs and maintenance costs.

On the other hand, in the conventional dry pretreatment method, the cladding tubes are cut open one by one without shearing and only the spent fuel in the inside is taken out. It led to the enlargement of the process.

The pretreatment method of oxidizing the spent fuel together with the cladding tube at a high temperature and naturally crushing the fuel by thermal expansion has reached the stage of research and development, but does not generate shear metal powder, The current situation is that the pretreatment device is becoming larger and the operation is complicated.

Therefore, an object of the present invention is to improve the problems of the above-mentioned conventional pretreatment method for spent fuel, shorten the melting time of the melting tank, and solve the problem of accumulation of sheared metal powder generated during shearing. In addition to the new and improved spent fuel, the melting tank itself and the equipment structure and operation method after the melting tank can be simplified, and the equipment manufacturing cost, operation cost, and maintenance cost can be significantly reduced. It is an object of the present invention to provide a treatment method and a pretreatment device.

A further object of the present invention is to provide a spent fuel pretreatment apparatus which can make the apparatus itself compact, reduce the manufacturing cost of equipment, and reduce the installation space.

[0013]

That is, the method for pretreatment of spent fuel of the present invention is to pulverize spent fuel rods in a fast reactor or fast breeder reactor together with an austenitic stainless steel cladding tube into particles or powder. Process, step of magnetically collecting and removing clad tube crushed product from crushed product to separate spent fuel crushed product, transferred separated spent fuel crushed product to nitric acid dissolving tank or molten salt electrolytic tank for processing It is characterized by comprising the steps of:

According to such a pretreatment method, the austenitic stainless steel cladding tube is transformed into martensitic stainless steel by the shearing stress in the crushing process, so that it becomes ferromagnetic. Therefore, it becomes possible to magnetically and efficiently collect and remove the pulverized product of the coated tube from the pulverized product.
The spent fuel pulverized product can be easily separated. As a result, the amount of crushed coated tube pulverized material transferred to the melting tank or the molten salt electrolysis tank is significantly reduced, and the accumulation of pulverized coated tube pulverized material in the melting tank or molten salt electrolysis tank can be prevented. Further, since the spent fuel pulverized product is made into finer particles or powder than the conventional sheared product, it is possible to shorten the dissolution time in nitric acid or molten salt.

Furthermore pretreatment device of the spent fuel of the present invention, o the spent fuel rods in fast reactors or fast breeder reactor
-Insert part for vertically inserting the whole cladding tube made of austenitic stainless steel, crushing part for sequentially crushing the inserted spent fuel together with the cladding tube from the lower end, and a filter for passing only the crushed product crushed to a predetermined size Part, and a magnetic separation part for magnetically collecting and removing the crushed product of the cladding tube in the crushed product that has passed through the filter part and transferring only the spent fuel crushed product to the nitric acid dissolving tank or the molten salt electrolysis tank. It is characterized by that.

The above-mentioned crushing section may have a structure having a rotary rotor having a plurality of shear blades mounted on the outer circumference, or a structure having a rotary rotor having a plurality of hammers swingably mounted on the outer circumference.

Further, the above-mentioned magnetic separation portion has a magnetic separation means, which is provided on one side inside the rotary drum, with a fixed magnet which does not rotate together with the rotary drum and which corresponds to approximately half the circumference of the rotary drum. Provided below the rotary drum on the side where the fixed magnets are provided is a transfer pipe for transferring the spent fuel pulverized product to the nitric acid dissolving tank or the molten salt electrolysis tank, and below the rotary drum on the side where the fixed magnets are not installed. A structure provided with a discharge pipe for discharging the crushed material of the cladding pipe, or a plurality of rod-shaped magnets that can be inserted and removed from the outside of the pipe so as to cross the pipe diameter in the middle of the pipe, and the spent fuel downstream of the pipe A transfer pipe for transferring the crushed product to the nitric acid dissolving tank or the molten salt electrolysis tank may be connected, and a discharge pipe with a switching valve may be provided for branching from the pipe to discharge the crushed product of the covering pipe. it can.

According to such a pretreatment apparatus, since the crushing section and the magnetic separation section can be collectively disposed in one apparatus as a series of processes, the apparatus as a whole can be made compact. Furthermore, since the spent fuel rods are inserted vertically, the installation space of the device can be significantly reduced as compared with the conventional shearing device that is inserted horizontally.

The "crushed product of coated tube" in the present specification
The term is used as a term that includes not only the cladding tube but also other metal pulverized materials attached to fuel rods such as space wires.

[0020]

1 is an explanatory view showing an embodiment of a pretreatment apparatus of the present invention, in which an insertion part A, a crushing part B, a filter part C and a magnetic separation part D are vertically arranged in this order. It is arranged in an array. The insertion portion A is a device that inserts the spent fuel rod 1 in the vertical direction and pushes it toward the crushing portion B. The crushing unit B has a structure having a rotating rotor 3 having a plurality of shear blades 2 attached to the outer periphery thereof, and is a device for sequentially crushing the inserted spent fuel rods 1 together with the cladding tube from the lower end thereof.

The filter section C is composed of a filter 4 having a mesh which allows only the crushed material crushed by the crushing section B to have a predetermined size or smaller. In addition, a discharge pipe 6 for discharging the metal piece 5 that has not been crushed to a predetermined size or less.
Is provided on the side wall of the crushing section B directly above the filter 4.

The magnetic separation section D comprises a rotary drum 8 having a fixed magnet 7 arranged therein, and the rotary drum 8 is rotating in the direction indicated by the arrow. The fixed magnet 7 does not rotate together with the rotating drum 8 and is arranged on one side of the inner portion of a portion corresponding to substantially a half circumference of the rotating drum 8. A transfer pipe 10 for transferring the spent fuel pulverized material 9 to a nitric acid dissolving tank or a molten salt electrolytic tank (neither is shown) is provided below the rotary drum on the side where the fixed magnet 7 is arranged. ing. Further, below the rotary drum on the side where the fixed magnet 7 is not arranged, a discharge pipe 12 for discharging the crushed product 11 of the coated pipe is provided. Further, a compressed air blowing pipe 1 for blowing compressed air 13 toward the rotary drum 8 on the side where the fixed magnet 7 is disposed.
4 is disposed obliquely below the rotary drum 8. The fixed magnet 7 may be a permanent magnet or an electromagnet.

The operation of the pretreatment apparatus of the present invention having the above-mentioned structure will be described, and the pretreatment method of the present invention will also be described. The spent fuel rod 1 vertically pushed into the insertion portion A of FIG. 1 has its insertion lower end pushed toward the rotating rotor 3 rotating in the crushing portion B, and has a plurality of shear blades on the outer periphery of the rotating rotor 3. 2, the cladding of the fuel rod 1 is pulverized together with the spent fuel pellets therein into a granular or powder form having a diameter of about 3 mm or less. One feature of the present invention is that it is finely pulverized as compared with a conventional sheared product having a diameter of about 3 cm obtained by shearing.

The metal pieces 5 that have not been crushed to a predetermined size or smaller by the rotating rotor 3 are removed by the filter 4 installed in the filter section C, discharged and discharged from the discharge pipe 6, and treated as solid waste.

The pulverized material that has passed through the filter 4 falls onto the rotary drum 8 of the magnetic separation section D. The austenitic stainless steel cladding tube in the pulverized material has been transformed into ferromagnetic martensitic stainless steel due to shear stress in the pulverized portion. Therefore, the outer surface of the rotary drum 8 is fixed by the fixed magnet 7 inside the rotary drum 8. Are magnetically collected by the rotating drum 8 and rotate with the rotation of the rotating drum 8. On the other hand, the non-magnetic spent fuel pulverized material that has dropped onto the rotating drum 8 is not magnetically collected on the outer peripheral surface of the rotating drum 8 and remains on the rotating direction side (the right side in the drawing of FIG. 1) of the rotating drum. The spent fuel pulverized material transfer pipe 10 is opened downward, and is transferred to a nitric acid dissolving tank or a molten salt electrolytic tank for processing.

The crushed coated tube which is collected on the outer peripheral surface of the rotating drum 8 and rotates together with the rotating drum 8 passes through the lowermost end of the rotating drum 8 without falling into the transfer tube, but the fixed magnet 7 is provided. When it rotates toward the non-rotating side, it is released from the magnetic capture by the fixed magnet 7, falls from the outer peripheral surface of the rotating drum 8, is guided to the discharge pipe 12 opening below the rotating drum 8 and is removed, and the solid waste is discarded. Processed as a thing.

The crushed product of the cladding tube magnetically collected on the outer peripheral surface of the rotary drum 8 has a crushed product of the spent fuel in the form of fine particles or fine powder attached thereto. It is necessary to collect it as spent fuel pulverized products. The collection of deposits is
From the compressed air blowing pipe 14 to the compressed air 13 to the crushed product of the coated pipe in a state of being magnetically collected on the outer peripheral surface of the rotary drum 8.
This can be effectively carried out by spraying and blowing off only the spent fuel pulverized product adhering to the pulverized product of the cladding tube.

A knocker device (not shown) that gives a slight impact to the rotary drum 8 is installed without blowing the compressed air 13 to cover the outer peripheral surface of the rotary drum 8 magnetically. The spent fuel pulverized material adhering to the clad pipe pulverized product can also be removed by giving a light impact to the pulverized pipe product.

Thus, most of the metal powder such as the crushed product of the cladding tube is not transferred to the nitric acid dissolving tank or the molten salt electrolysis tank, and the dissolution treatment of the spent fuel crushed product into nitric acid or the molten salt can be carried out efficiently. It can be carried out. In the actually conducted experiment, the efficiency of collecting the pulverized product of the coated tube can be achieved at about 70% by weight, and the amount of the coated tube transferred to the dissolution tank can be reduced to 1/3 or less of the conventional amount.

Further, the dissolution time of the spent fuel in the solvent can be shortened as the contact area between the two increases. For example, the contact area (surface area) when the spent fuel pulverized product in the present invention is considered as a granular product having a diameter of about 2 mm is
Approximately 6 mm in diameter and 3 c in length obtained by conventional shearing
About 50 times the contact area (surface area) of the sheared object of m,
Therefore, the dissolution time can be shortened to a maximum of about 1/50.

FIG. 2 is an explanatory view showing another embodiment of the pretreatment apparatus of the present invention. Only the magnetic separation part D is different from the embodiment of FIG. 1, and other parts are the same as those of the embodiment of FIG. Is the same as. Therefore, the same components as those in FIG. 1 are designated by the same reference numerals as those in FIG. In the magnetic separation part D'in the embodiment of FIG. 2, the pipe 15 extending downward from the bottom of the filter part C is slightly inclined, and a plurality of bar-shaped magnets are provided in the middle of the pipe 15 from outside the pipe so as to cross the pipe diameter. 16 is arranged so that it can be inserted and removed. Further, a transfer pipe 10 for transferring the spent fuel pulverized material 9 to a nitric acid dissolving tank or a molten salt electrolytic tank is connected downstream of the portion of the pipe 15 where the rod-shaped magnets are arranged. Further, a discharge pipe 12 for discharging the crushed product 11 of the coated pipe is branched in the pipe 15 downstream of the bar magnet arranging portion so as to extend in a substantially vertical direction. The discharge pipe 12 is switched to a branch point. A valve 17 is provided.

In such a magnetic separation section D ', the crushed material that has passed through the filter 4 is guided to the pipe 15, and when it passes through the portion where the bar-shaped magnet 16 is disposed, the crushed material of the ferromagnetic coating tube in the crushed material is crushed. The substance is magnetically collected on the surface of the rod-shaped magnet 16, and the non-magnetic spent fuel pulverized product is guided to the transfer pipe 9 without being magnetically collected by the rod-shaped magnet 16 and is fed into a nitric acid dissolving tank or a molten salt. It is transferred to the electrolytic cell and processed. At this time, the switching valve 17 provided at the branch point of the discharge pipe 12 branched from the pipe 15 closes the branch point so that the spent fuel pulverized product does not drop into the discharge pipe 12.

The finely pulverized or finely powdered spent fuel adhering to the clad tube pulverized material electromagnetically collected on the surface of the rod-shaped magnet 16 is compressed air 13 into the compressed air blowing tube 14.
It can be wiped off by spraying the powder toward the crushed product of the cladding tube. A knocker device (not shown) that gives a light impact to the bar-shaped magnet 16 without blowing the compressed air 13.
It is also possible to remove the spent fuel pulverized product adhering to the pulverized product of the cladding tube by applying a light impact to the pulverized product of the coated pipe in a state of being collected by the rod-shaped magnet 16. This is the same as the first embodiment.

On the other hand, for the crushed product of the coated tube collected by the bar-shaped magnet 16, after temporarily stopping the crushing operation in the crushing section C, the switching valve 17 provided at the branch point of the discharge pipe 12 is switched to open, Then, the rod-shaped magnets 16 can be pulled out, the crushed products of the coated tube can be blown off from their surfaces, and they can be dropped into the discharge pipe 12 and discharged. After removing the crushed product of the coated tube, the rod-shaped magnet 16 is again inserted into the pipe 15, the switching valve 7 is closed, and then the crushing operation in the crushing unit C is restarted to start the next operation. can do.

In the crushing section B of the pretreatment apparatus shown in FIGS. 1 and 2, the rotary rotor 3 having the shear blade 2 attached to the outer periphery thereof is used.
Although the embodiment using the above is shown, as shown in FIG. 3, it is also possible to use a rotary rotor 23 in which a plurality of hammers 22 are swingably attached to the outer periphery by pins 21.

In the above-mentioned pretreatment method of the present invention,
An embodiment in which after performing a step of magnetically collecting and removing the crushed clad tube to separate the crushed spent fuel, the separated crushed spent fuel is transferred to a nitric acid dissolution tank to be subjected to dissolution treatment will be described. However, the granular or powdery pulverized product obtained in the pulverization process was directly transferred to the nitric acid dissolution tank to dissolve only the spent fuel pulverized product in the pulverized product, and the undissolved clad tube pulverized product was It may be magnetically collected and removed from the dissolution treatment liquid. In the present invention, the clad tube of the spent fuel rod is crushed into finer particles or powder than the conventional clad tube shearing material (hull) in the crushing process, so that a comparatively large clad tube shear such as hull is crushed. There is little risk of deposits of substances in the dissolution tank, and the frequency of magnetically separating and removing the crushed product of the coated tube from the nitric acid solution can be far less than the frequency of removing the conventional sheared product of the coated tube.

The granular or powdery pulverized product obtained in the pulverization step is transferred as it is to a molten salt electrolysis tank for dissolution by molten salt and electrolysis, and then the pulverized product of the coated tube is magnetically captured. The embodiment of collecting and removing is not very suitable. This is because the crushed product of the coated tube itself may affect the electrolytic ability of the electrolytic cell.

[0038]

As can be seen from the above detailed description, according to the present invention, when a spent fuel rod is sheared together with a cladding tube and pretreated in a nitric acid dissolving tank or a molten salt electrolytic cell, a conventional sheared material is used. After crushing into finer granules or powder and magnetically collecting and removing the crushed product of the cladding tube in the crushed product, only the spent fuel crushed product was pretreated in the nitric acid dissolving tank or molten salt electrolytic tank Therefore, it is possible to significantly reduce the amount of the coated tube pulverized product transferred to the dissolution tank as compared with the conventional case. As a result, metal powder is less likely to be deposited inside the melting tank and piping, and the melting tank itself and the device structure and operation method after the melting tank can be simplified, thus reducing operating costs and maintenance costs. Is possible.

Further, since the spent fuel pulverized product is pulverized into fine powdery or granular form, the contact area with the solvent is increased, and as a result, the dissolution time can be greatly shortened. As a result, the size of the melting tank and the electrolytic tank can be significantly reduced, and the device manufacturing cost can be significantly reduced.

Further, the crushed product of the coated tube which is finally recovered as radioactive solid waste is also finely crushed as compared with the conventional sheared product, so when filling the hull can, one hull can is filled. The filling amount per hit can be increased. As a result, the number of hull cans can be reduced, and the disposal cost for underground disposal of radioactive waste can be reduced.

Further, according to the pretreatment apparatus of the present invention, since the spent fuel rods can be handled in the vertical direction, the apparatus as a whole can be made compact as compared with the conventional horizontal type shear treatment apparatus. It is possible to reduce the manufacturing cost and the installation space.

Furthermore, since the pretreatment device of the present invention has a relatively simple structure, it is possible to perform individual maintenance for each component by using a remote control device such as a manipulator or a robot.
Inspection and parts replacement are possible.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of a pretreatment device of the present invention.

FIG. 2 is an explanatory view showing another embodiment of the pretreatment apparatus of the present invention.

FIG. 3 is an explanatory view showing another embodiment of a rotary rotor for pulverization that can be used in the pretreatment device of the present invention.

[Explanation of symbols]

A: Insertion part 15: Piping B: Grinding unit 16: Bar magnet C: Filter 17: Switching valve D: Magnetic separation part 22: Hammer 1: Spent fuel rod 23: Rotating rotor 2: Shear blade 3: Rotating rotor 4: Filter 7: Fixed magnet 8: rotating drum 9: Crushed spent fuel 10: Transfer tube 11: Crushed tube 12: Discharge pipe 13: Compressed air 14: Compressed air blowing tube

Continuation of the front page (56) Reference JP-A-8-224498 (JP, A) JP-A-11-14797 (JP, A) JP-A-59-59807 (JP, A) JP-A-60-4890 (JP , A) Suzuki, A., Washiya, T., Koyama, S. I29 Development of large particle size sludge separation technology in pretreatment process, Atomic Energy Society of Japan, "Autumn of 2000" Proceedings, Japan, Atomic Energy Society of Japan, 2000 8 10th, 3rd volume, P555 Yoshiaki Suzuki, Tadahiro Washiya, Tomozo Koyama, Martensitic transformation of N12 shear metal powder, Atomic Energy Society of Japan, "Annual Meeting of Spring 2001", Japan, Atomic Energy Society of Japan, March 5, 2001, P718 Seiya Yamada, Tsutomu Koizumi, Tomozo Koyama, Teruo Hara, Hidenori Yamato, Development of mechanical decoating method for N2 fast reactor fuel reprocessing (1) -Multiaxial shear fracture method Decoating Preliminary Test by Atomic Energy-, Atomic Energy Society of Japan "Autumn Meeting of 2001", Japan, This Atomic Energy Society, August 10, 2001, P801 Seiya Yamada, Masayuki Takeuchi, Tsutomu Koizumi, Tomozo Koyama, Kazuo Takami, Teruo Hara, B58 Development of mechanical decoating method for fast reactor fuel reprocessing (2) − De-coating element test by biaxial shear crushing method, Proceedings of Atomic Energy Society of Japan "Autumn 2002 Conference", Japan, Japan Atomic Energy Society, August 5, 2002, P524 Masayuki Takeuchi, Seiya Yamada, Tsutomu Koizumi, Satoshi Koyama Zouzo, Kazuo Takami, Teruo Hara, B59 Development of mechanical decoating method for fast reactor fuel reprocessing (3) -Fuel separation basic test by magnetic separation method-, Atomic Energy Society of Japan "Autumn 2002 Fall" Proceedings, Japan , Japan Atomic Energy Society, August 5, 2002, P525 (58) Fields investigated (Int.Cl. ⁷ , DB name) G21C 19/36 G21C 19/44

Claims (10)

(57) [Claims] 1. A step of pulverizing spent nuclear fuel rods in a fast reactor or a fast breeder reactor together with an austenitic stainless steel cladding tube into a granular or powder form, and magnetically collecting and removing the pulverized cladding material from the pulverized material. And a process for separating the separated spent nuclear fuel pulverized product into a nitric acid dissolving tank or a molten salt electrolytic bath for processing. 2. After the spent nuclear fuel pulverized product is separated, it is adhered to the pulverized product of the cladding tube by blowing compressed air or applying a light impact to the pulverized product of the cladding tube in a magnetically collected state. The pretreatment method for spent nuclear fuel according to claim 1, further comprising a step of scraping off and recovering the spent nuclear fuel pulverized product. 3. A process of pulverizing a spent nuclear fuel rod in a fast reactor or a fast breeder reactor together with a cladding tube into a granular or powder form,
A step of transferring the crushed pulverized product to a nitric acid dissolving tank or a molten salt electrolysis tank to perform a nitric acid dissolving treatment or a molten salt electrolytic treatment of the spent nuclear fuel pulverized product, and magnetically collecting and removing the pulverized clad tube from the treatment liquid. A pretreatment method for spent nuclear fuel, comprising a process. 4. An insertion part for vertically inserting a spent nuclear fuel rod in a fast reactor or a fast breeder reactor together with an austenitic stainless steel cladding tube, and the inserted spent nuclear fuel together with the cladding tube is crushed sequentially from the lower end. A crushing unit and a filter unit that allows only a crushed product crushed to a predetermined size to pass through,
It is characterized by comprising a magnetic separation part for magnetically collecting and removing the crushed product of the cladding tube in the crushed product that has passed through the filter part and transferring only the spent nuclear fuel crushed product to the nitric acid dissolving tank or the molten salt electrolytic tank. Pretreatment equipment for spent nuclear fuel. 5. The spent nuclear fuel pretreatment device according to claim 4, wherein the crushing unit has a structure having a rotating rotor having a plurality of shear blades attached to the outer periphery thereof. 6. The spent nuclear fuel pretreatment device according to claim 4, wherein the crushing unit has a structure having a rotary rotor on the outer periphery of which a plurality of hammers are swingably mounted. 7. The magnetic separation unit has a magnetic separation means, which is provided on one side inside the rotary drum, with a fixed magnet which does not rotate together with the rotary drum and which corresponds to approximately half a circumference of the rotary drum. A transfer pipe for transferring the spent nuclear fuel pulverized product to the nitric acid dissolving tank or the molten salt electrolysis tank is provided below the rotary drum on the side where the fixed magnet is provided, and below the rotary drum on the side where the fixed magnet is not provided. A structure provided with a discharge pipe for discharging the crushed product of the covering pipe is characterized in that
The spent fuel pretreatment device according to any one of 6 above. 8. The surface of the rotary drum, wherein a compressed air blowing pipe for blowing compressed air toward the fixed drum is provided, or a knocker for giving a light impact to the rotary drum is provided. The spent nuclear fuel pulverized material adhered to the pulverized material of the cladding tube that is magnetically collected in the above is scraped off and collected.
The pretreatment device for spent nuclear fuel according to 1. 9. The magnetic separation unit is provided with a plurality of rod-shaped magnets in the middle of the pipe so as to be able to be inserted and removed from the outside of the pipe so as to traverse the pipe diameter, and the spent nuclear fuel pulverized product is placed in a nitric acid dissolving tank or a downstream of the pipe. 5. A structure in which a transfer pipe for transferring to the molten salt electrolyzer is connected and a discharge pipe with a switching valve for branching from the pipe and discharging the crushed product of the coated pipe is provided. The spent fuel pretreatment device according to any one of 6 above. 10. A compressed air blowing tube for blowing compressed air toward the rod-shaped magnet is arranged, or a knocker for giving a light impact to the rod-shaped magnet is arranged to magnetically collect on the surface of the rod-shaped magnet. The spent nuclear fuel pretreatment device according to claim 9, wherein the spent nuclear fuel pulverized material adhering to the clad tube pulverized material is scraped off and collected.