JP2000038623A - Separation of radio active particles, separation system and apparatus for separation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To separate uranium, plutonium or compounds thereof by the use of magnetic attraction. SOLUTION: A method for separating radio active particles comprises flowing a fluid to be treated, containing the radio active particles, into a magnetized rotary tube, then magnetically attracting the particles to a magnetic pole provided in the tube to separate the particles from the fluid, further, after demagnetizing the magnetism in the tube, flowing a cleaning fluid backward into the tube to take the radio active particles together with the cleaning fluid from the tube and finally separating the radio active particles from the cleaning fluid.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radioactive particle for the purpose of magnetically separating radioactive particles to increase the concentration of radioactive particles or to efficiently treat radioactive particles from radioactive waste. The present invention relates to a separation method, a separation system, and a separation device.

[0002]

2. Description of the Related Art Conventionally, in order to utilize uranium, uranium ore is first collected, refined into a yellow cake, and then uranium 235 (uranium to fission) is enriched. For this enrichment, after converting uranium to a gaseous form (UF ₆ ), it is subjected to an ultra-high-speed centrifugal separator or the like to convert 0.7% of uranium 235 in natural uranium (uranium 238 other than fission) into about 4%.
% And then chemically treated to remove uranium dioxide (U
O ₂ ), which is pulverized and then molded into a fuel rod.
Also, spent fuel rods are separated into uranium, plutonium and radioactive waste in a reprocessing plant, and the uranium and plutonium are processed again into fuel rods and reused, and the radioactive waste is sealed and stored.

[0003]

The enrichment of uranium 235 from the uranium ore or separation of uranium and plutonium from spent fuel rods is generally carried out by gasification (UF ₆ ) method, It has been adopted in all countries, but it has problems such as inefficiency, enormous equipment and time, and an increase in the power cost of nuclear power plants.

Although magnetic separation of radioactive materials, which has been experimentally studied, is possible, it is difficult to efficiently collect the separated radioactive particles, and the stronger the magnetic force, the better the separation efficiency, but on the other hand, the demagnetization and magnetic adhesion There was a problem that was not technically solved for collection of garbage.

[0005]

According to the present invention, a cylinder containing a matrix for magnetic poles is rotatably mounted on a fluid to be treated, and a solenoid coil is installed facing the outside of the cylinder to supply the fluid to both ends of the cylinder. A feed pipe and a discharge pipe are connected, and each of the pipes is connected to a storage tank for a fluid to be treated, a storage tank for a discharge fluid, a storage tank for a cleaning fluid, and the like via an automatic opening / closing valve and a necessary pump, and the pipes are cleaned. Since the fluid supply / discharge pipe is interposed, the suction by the magnet and the removal of the adsorbed material by the demagnetization can be performed smoothly, thereby solving the above-mentioned conventional problems.

[0006] That is, the invention of the method is such that a fluid to be treated containing radioactive particles is sent into a magnetized rotating cylinder, magnetically attached to a magnetic pole in the cylinder, radioactive particles are separated from the fluid, and then the radioactive particles in the cylinder are separated. A method for separating radioactive particles, characterized in that after demagnetization, a cleaning fluid is sent into a cylinder, radioactive particles are taken out of the cylinder together with the cleaning fluid, and the radioactive particles and the cleaning fluid are separated.

[0007] The invention of a system also includes a fluid adjusting means for pulverizing a radioactive material to be processed into fine particles and dispersing the same into water or other fluid to obtain a fluid to be processed, and a rotating cylinder magnetizing the fluid to be processed. Feeding means for feeding the cleaning fluid into the inside of the cylinder, magnetizing means for magnetizing radioactive particles in the fed fluid to the magnetic poles in the cylinder, demagnetizing the magnetism in the cylinder, and pressurizing and supplying the cleaning fluid. Feeding means for taking out the radioactive particles in the cylinder together with the cleaning fluid, and a separating means for separating the discharged radioactive particles from the cleaning fluid are sequentially connected, and all the means are protected against radiation. A radioactive particle separation system characterized by being shielded from the outside by means, wherein the radioactive material to be processed is uranium or plutonium or a compound thereof and has magnetism. Next, the fluid adjusting means pulverizes the radioactive material into fine particles, and water is added to the particles to obtain a water content of 70% to 90%.
The feeding means is a feeding pipe provided with a pump, and the magnetizing means contains a matrix for magnetic poles in a cylinder and is provided outside the cylinder. The solenoid coil is installed facing the solenoid coil. Further, the discharge means of the radioactive particles is a demagnetization of the matrix in the cylinder and the cleaning fluid is pressurized and fed, the separation means of the radioactive particles is a specific gravity separation or filtration, and the radiation protection means is The cover wall is made of a radiopaque material.

According to another aspect of the present invention, a cylinder accommodating a matrix for magnetic poles is rotatably mounted on a machine base, and a solenoid coil is installed outside the cylinder so as to be opposed to the cylinder. And a fluid supply pipe and a discharge pipe connected to both ends of the cylinder, respectively, and each of the pipes is connected to a storage tank for a fluid to be treated, a storage tank for a discharge fluid, a storage tank for a cleaning fluid, etc. via an automatic opening / closing valve. A cleaning fluid supply pipe is interposed in each of the pipes, and the entire apparatus is installed in the radiation protection means. Next, the matrix for the magnetic pole is a ferromagnetic fine wire or a ferromagnetic net,
The solenoid coil has a plurality of coils arranged in parallel so that the magnetic force is sequentially increased in the flow downstream direction of the fluid to be processed.

The present invention can be used when enriching uranium in uranium ore, or when separating or enriching uranium or plutonium from spent fuel rods.

According to the present invention, since the cylinder filled with the matrix is rotated, the adsorption of the radiation particles is averaged, and the demagnetizing speed is increased.

The present invention focuses on the fact that uranium or plutonium or a compound thereof is weakly magnetic, and utilizes this to enable magnetic adhesion separation. Therefore, in order to perform magnetic adhesion and demagnetization reliably and quickly, a strong magnetic field (for example, 20,000 gauss or more) is generated and completely demagnetized (for example, current is cut off and the cylinder is rotated), and the cleaning fluid is pumped. It is.

In practicing the present invention, magnetic fields having different intensities are installed in parallel to promote magnetic adhesion according to the state of the radioactive particles of the fluid to be treated. For example, a relatively weak magnetic field (eg, 2
Tens of thousands of gauss) to a strong magnetic field (for example, 200,000 gauss) are divided into several parts. In addition, the magnet is magnetized with a strong magnetic field, and the length of the cylinder is changed (for example, 1 m to 3 m) according to the state of the fluid to be processed. As a result of the above, in the case of a relatively long strong magnetic field, particles having a small magnetic force are magnetized, so even if there is some residual magnetism during demagnetization, the magnetic force is easily lost. Therefore, there is an advantage that the elimination by the cleaning fluid can be reasonably completed.

As the cleaning fluid in the present invention, water or air and, if necessary, an inert gas (eg, nitrogen gas) are used. If it is the necessary limit and only the amount of natural decrease is replenished, operation of the system etc. of the present invention will not be affected,
Moreover, a large amount of equipment is not required for the radioactive removal processing of the cleaning fluid. For the radiation protection wall and the like in the present invention, any known protection material can be used.

Since the control target of the apparatus of the present invention is an automatic valve (for example, an electromagnetic valve) and a pump, both can be easily operated remotely, so that there is no problem in safety, and the circulating use of the cleaning fluid can be started. Since only uranium or plutonium or a compound thereof is taken out, no problem may occur even if the conventional protection standard is applied as it is.

In short, it is a simple and reliable device that can perform safe, reliable, and inexpensive processing, as well as having no room for causing an accident. Together, this is a feature of the present invention.

[0016]

DETAILED DESCRIPTION OF THE INVENTION The present invention focuses on the fact that uranium or plutonium or a compound thereof is weakly magnetic,
The main purpose is magnetic separation. For magnetic separation, it is necessary to make uranium or plutonium or the like magnetically attachable (particulate) and fluidized (for example, a mixed solution).
Furthermore, in order to magnetize weak magnetic particles efficiently, a magnetic field having a necessary strength must be provided, and demagnetization upon removal must be performed quickly. Generally, the time required for demagnetization is shorter in the case of a weak magnetic field than in the case of a strong magnetic field (because there is less residual magnetism).

As described above, uranium or plutonium is weakly magnetic, but it is clear that the magnetic adhesion differs depending on the state of the particles. Therefore, particles that are relatively easily magnetized are adsorbed by a relatively weak magnetic field, and particles that are relatively hard to magnetize (for example, non-magnetic powder is fixed to the outside of uranium particles,
A strong magnetic field is required (when integrally solidified). In the above, in the case of a weak magnetic field, the time until demagnetization is short, and in the case of a strong magnetic field, it takes a long time to demagnetize.However, in a strong magnetic field, a strong magnetic field is necessary because the magnetic force of the magnetized particles is small. Therefore, even if the complete demagnetization cannot be performed, it is easy to take out the magnetically adhered particles (magnetically released).

Therefore, when the current of each solenoid coil is cut off all at once and the cleaning fluid is fed, the particles magnetically attached to the matrix in the cylinder are uniformly taken out and there is no possibility of remaining. In other words, even if there is some residual magnetism in a strong magnetic field, the magnetic adhesion of the particles cannot be continued because the magnetic force of the particles is small.
In the above, it is also possible to individually cut off the input of the electromagnetic coil according to the strength of the magnetic field, and separately extract relatively strong magnetic radioactive particles and relatively weak magnetic radioactive particles.
Therefore, how to take out is determined in consideration of the properties of the magnetized radioactive particles and the difficulty of the subsequent separation.

[0019]

Embodiment 1 An embodiment of the present invention will be described with reference to FIG.

Uranium ore is pulverized, and water is added to the pulverized ore to obtain a fluid to be treated having a water content of 90%, which is fed to a cylinder by a pump. The cylinder is filled with a ferromagnetic matrix, and a solenoid coil is wound around the outside of the cylinder, so that the uranium particles are magnetized by the magnetization of the matrix, and the remaining liquid separated from the uranium particles is solidified as a discharge fluid. The liquid is separated, the water is circulated again as water for addition, and the solids are treated and disposed of with or without radiation.

When sufficient uranium particles are magnetically attached to the matrix (for example, automatic control by a timer), the power supply of the solenoid coil is cut off to demagnetize the magnet, and then a cleaning fluid is supplied to remove the magnetically-coated uranium particles from the cleaning fluid. Take out with. The removed mixed fluid is separated into solid and liquid, the cleaning fluid is returned to the cleaning fluid tank and circulated for use, and the particles are sent to the next step of separating uranium 235, and then processed into fuel rods by known processing means.

Although the above is an embodiment in which uranium is separated from uranium ore, the same applies to spent fuel rods except for the grinding step. However, in the case of spent fuel rods, uranium and plutonium are separated, but after separation, they can be processed by currently used processing steps.

In short, the method of the present invention provides a method for enrichment of uranium or plutonium.

[0024]

Second Embodiment A system according to the present invention will be described with reference to FIG.

The uranium ore is pulverized to a predetermined particle size (for example, about 1 mm) by a pulverizer, and put into a stirrer together with water fed from a water tank by a feeding means such as a pump to stir to form a uniform mixed liquid. . Next, this mixed solution is fed into the cylinder by a pump or the like. Since the inside of this cylinder is filled with a matrix composed of ferromagnetic wires and the outside is provided with a solenoid coil, when a current is applied to the solenoid coil, a magnetic field is formed (in this case, the minimum is 20,000 gauss). ). Therefore, the countless N.D.
An S magnetic pole is generated to magnetize uranium particles. In this case, a plurality of solenoid coils are arranged in parallel outside the cylinder with respect to the center axis direction, so that a strong magnetic force is sequentially generated in the downstream direction of the flow of the mixture. For example, 2
10,000 to 200,000 gauss. Therefore, uranium particles that are easily magnetized are magnetized at a place where the magnetic force is small, and uranium particles that are hardly magnetized are magnetized at a place where the magnetic force is large. That is, although the uranium particles have the same weak magnetism, if non-magnetic particles are attached to the uranium particles, it becomes difficult to magnetically adhere.

In the above description, if the cylinder is rotated, the magnetized density is equalized and the magnetized magnets are averaged, so that the next demagnetization separation can be performed rationally. Mixture of constant concentration (0.7 in particles)
% Of uranium particles), the time to reach saturation magnetization is almost constant. Therefore, immediately before saturation magnetization, the current of the solenoid coil is cut off, and after demagnetization, the cleaning fluid is pressurized (for example, If the pressure is 5 kg / cm ² ), the uranium particles magnetically attached to the matrix in the cylinder are removed together with the cleaning fluid. Therefore, uranium particles and a cleaning fluid are separated (for example, specific gravity selection or filtration), and then uranium is converted to a gaseous form (U
F ₆ ), the uranium 235 and the uranium 238 are separated by an ultra-high speed centrifuge, and then the uranium 235 is chemically treated into uranium dioxide (UO ₂ ).
Form into fuel rods.

As described above, since uranium can be efficiently separated from uranium ore, uranium can be concentrated at a relatively low cost as compared with the conventional method.

Although the above embodiment has described uranium ore, the same applies to spent fuel rods. In the case of a spent fuel rod, since uranium 235 and plutonium are magnetically bonded, the fuel rod can be reshaped without separation or without separation.

[0029]

Embodiment 3 An embodiment of the present invention will be described with reference to FIG. Uranium ore is crushed, and water is added to the crushed
% Of the mixture (fluid to be treated),
To the separation cylinder 4. In this case, valve 5,
Open 6, 7, 8 and open valves 9, 10, 11, 12, 23
Is closed, the mixture enters the separation cylinder 4 as shown by arrows 14 and 15. The separation cylinder 4 is filled with a ferromagnetic matrix 16 on the inside and a plurality of sets of solenoid coils 1 on the outside.
7, 17a, 17b, and 17c are sequentially installed in parallel.
The solenoid coils 17, 17a, 17b, 17c
The magnetic force increases as it goes to the downstream side of the mixed solution feeding. For example, the solenoid coil 17 has 20,000 gauss,
17c is 200,000 gauss, and the middle is increased almost evenly.

Therefore, the uranium particles that are relatively easily magnetized in the mixed solution are adsorbed by the matrix located inside the solenoid coil 17, and the uranium particles that are relatively hard to magnetize (for example, the uranium particles and the non-magnetic particles adhere to each other). Particles) are magnetically attached to a matrix with a high magnetic force. The remaining mixture obtained by separating the uranium particles as described above is indicated by arrows 20 and 2,
As indicated by reference numerals 1 and 39, the liquid collects in the discharge tank 22 via the valves 6, 7, and 8. When the uranium particles magnetized in the separation cylinder 4 become saturated, the valves 5 and 7 are closed (for example, closed by a timer), the valves 23 and 12 are opened, and the valve 24 is closed, the mixed liquid Enters the separation cylinder 4a as indicated by arrows 14, 35 and 36, magnetically separates uranium particles by the filled matrix, and the remaining mixture is
After passing through 2 and 8, they are accumulated in the discharge tank 22 as indicated by arrows 37, 38 and 39.

On the other hand, when the valves 11 and 9 are opened and the pump 25 is started, fresh water for cleaning is supplied from the water tank 26 as indicated by arrows 2.
7, 28, 29, 30 (for example, 5 kg / c
m ² ), and the mixed solution in the separation cylinder 4 is returned to the tank 1.

When the mixture is returned in this way,
The valve 9 is closed, the valve 10 is opened, and the current of all the solenoid coils 17, 17a, 17b, 17c is cut off. When the matrix is demagnetized in this way and the magnetic adhesion of the uranium particles is lost, when the fresh water is pumped from the pump 25, the uranium particles are mixed with the clear water by arrows 28, 29, and 3, as shown in FIG.
Since it flows like 1 and 32 and is sent to the collection tank 33, one step of magnetically attaching and separating uranium particles and collection is completed.

When the magnetic adhesion of the uranium particles has reached a saturated state in the separation cylinder 4a (as determined by a timer or the like), the valves 23, 12 are closed, and the valves 5, 6, 7 are opened. The mixture is fed to the separation cylinder 4 by the pump 2, uranium particles are magnetically attached to the matrix in the separation cylinder 4, and the remaining mixture is discharged to the discharge tank 22.
If the valves 3 and 13 are opened, the valve 11 is closed and the pump 25 is started, the fresh water is supplied from the water tank 26 as indicated by an arrow 27,
34, is fed into the separation cylinder 4a,
The mixed liquid remaining in the separation cylinder 4a as in 41 and 30 is returned to the tank 1. When the liquid mixture in the separation cylinder 4a is cleaned in this way, the valves 3, 10 are closed, the valve 24 is opened, and all the solenoid coils 17, 17a, 1
When the power sources of 7b and 17c are cut off, the magnetic flux is demagnetized and the magnetic force of the matrix is lost, and the uranium particles magnetized are sent together with the fresh water and accumulated in the collection tank 33. The mixed liquid in the collection tank 33 collected as described above is subjected to solid-liquid separation (specific gravity selection or filtration), and only the uranium particles are sent to the next step. In the above, since the cleaning fluid (clear water) and the separation liquid are circulated, there is no possibility that the cleaning fluid (clear water) increases to a certain amount or more.
When draining, radioactive particles are separated from the wastewater,
Check that radioactivity is gone and release.

The residue from which the uranium particles have been separated is radioactive, so it is subjected to solid-liquid separation, and the solid content is treated as a low-level radioactive solid. However, in the case of uranium ore residues, the radioactivity is significantly lower than that of excavation, and can be piled up and stored in a certain area (because of the separation of uranium particles).

The above-mentioned embodiment is installed in a radioactive protection room, and all valves and pumps are remotely operated. However, since only pumps, motors and solenoid valves are not operated, there is no possibility of failure and safety. The operation can be continued.

With respect to the above-mentioned protective room or protective wall, many partition walls and the like currently used can be used as they are.

[0037]

According to the method of the present invention, since radioactive particles are magnetically separated, not only the separation efficiency is good, but also
Outstanding enrichment effect. In addition, since the working fluid can be continuously used and the working fluid is circulated, it is easy to take measures against radiation.

The driving part according to the invention comprises an automatic valve,
The pump and the motor are advantageous in that automatic control is easy without failure and that radiation protection equipment can be completely installed. Further, by rotating the separation cylinder, the magnetic adhesion can be rationalized. Next, the solenoid coil was divided into multiple parts, and the magnetic field strength was sequentially increased toward the downstream side of the fluid to be treated.
The effect is that all the particles can be magnetized, and demagnetization and uranium particle extraction can be rationalized.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment of a method according to the present invention.

FIG. 2 is a block diagram of an embodiment of the invention of the system.

FIG. 3 is a conceptual diagram of the same invention of the apparatus.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Tank 2 Pump 4 Separation cylinder 5, 6, 7, 8, 9, 10, 11, 12, 13, 23,
24 Valve 16 Matrix 17, 17a, 17b, 17c Solenoid coil 22 Discharge tank 25 Pump 26 Water tank 33 Collection tank

Claims (12)

[Claims] 1. A fluid to be treated containing radioactive particles is sent into a magnetized rotating cylinder, magnetized on magnetic poles in the cylinder, radioactive particles are separated from the fluid, and the magnetism in the cylinder is demagnetized. Thereafter, a cleaning fluid is sent into the cylinder, the radioactive particles are taken out of the cylinder together with the cleaning fluid, and the radioactive particles and the cleaning fluid are separated from each other. 2. A fluid adjusting means for pulverizing a radioactive material to be processed into fine particles and dispersing the same in water or another fluid to obtain a fluid to be processed, and feeding the fluid to a rotating cylinder magnetized with the fluid to be processed. Feeding means, and magnetically attaching means for magnetizing the radioactive particles in the fed processing target fluid to the magnetic poles in the cylinder, and demagnetizing the magnetism in the cylinder, and pressurizing and feeding the cleaning fluid, Radioactive particles in the cylinder, the discharging means of radioactive particles to be taken out together with the cleaning fluid, and the discharged radioactive particles, the separating means for separating the cleaning fluid from the cleaning fluid are sequentially connected, and the entire means is connected to the outside world by radiation protection means. A radioactive particle separation system characterized by blocking. 3. The radioactive particle separation system according to claim 2, wherein the radioactive material is uranium, plutonium, or a compound thereof, and has magnetic properties. 4. The fluid adjusting means pulverizes the radioactive material into fine particles, and adds water to the particles to reduce the water content to 70% or less.
3. The radioactive particle separation system according to claim 2, wherein the mixed liquid contains 90% of particles. 5. The radioactive particle separation system according to claim 2, wherein the feeding means is a feeding pipe provided with a pump. 6. The radioactive particle separation system according to claim 2, wherein the magnetically attaching means has a matrix for magnetic poles accommodated in a cylinder, and a solenoid coil is opposed to the outside of the cylinder. 7. The radioactive particle separation system according to claim 2, wherein the radioactive particle discharging means demagnetizes the matrix in the cylinder and pressurizes and supplies the cleaning fluid. 8. The system for separating radioactive particles according to claim 2, wherein the means for separating the radioactive particles is specific gravity separation or filtration. 9. The radioactive particle separation system according to claim 2, wherein the radiation protection means has a cover wall made of a radiopaque material. 10. A cylinder accommodating a matrix for magnetic poles is rotatably mounted on a machine base, and a solenoid coil is opposed to the outside of the cylinder, and the cylinder and the solenoid coil are accommodated in a magnetic housing. A fluid feed pipe and a discharge pipe are connected to both ends of the cylinder, respectively, and the pipes are connected to a storage tank for a fluid to be treated, a storage tank for a discharge fluid, a storage tank for a cleaning fluid, and the like via an automatic opening / closing valve. A radioactive particle separating device, wherein a cleaning fluid supply pipe is interposed therebetween and all the devices are installed in radiation protection means. 11. The apparatus for separating radioactive particles according to claim 10, wherein the magnetic pole matrix is a ferromagnetic fine wire or a ferromagnetic net. 12. The radioactive particle separation apparatus according to claim 10, wherein the solenoid coil is provided with a plurality of coils whose magnetic force is sequentially increased in a flow downstream direction of the fluid to be treated, in parallel.