JPH11304988A - Dissolution tank - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dissolution tank capable of surely stirring solution liquid with a simple structure, by using a small diameter cylindrical dissolution tank dissolving hardly soluble material. SOLUTION: A dissolution tank 1 is provided with a small diameter cylindrical primary cylinder 2 and a secondary cylinder 3. The primary cylinder 2 is provided at the side wall with a shoot 5 for introducing hardly soluble nuclear fuel inside and an anode 4 dipped in the solution at the lower part. In the secondary cylinder 3, a diaphragm 6 and a cathode 7 arranged in the diaphragm are provided. The primary cylinder 2 and the secondary cylinder 3 are connected by a pair of upper connection pipes 8. The dissolution tank 1 is provided with a circulation pump 11 outside the two cylinders 2 and 3, and a lower connection pipe 14 is provided in between the bottom of the secondary cylinder 3 and the circulation pump 11. The circulation pump 11 circulates the solution 12 from the secondary cylinder 3 side to the primary cylinder 2 and stirs and unifies the solution 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention dissolves a sparingly soluble substance such as a nuclear fuel in a limited space by an electrolytic oxidation method, and adjusts the valence of an oxidizing agent (AgNO ₃ ) by an electrolytic oxidation method. It relates to a dissolution tank.

[0002]

2. Description of the Related Art FIG. 2 shows a conventional electrolytic dissolving tank 51.
As shown in the figure, the electrolytic dissolving tank 51 includes a primary side cylinder 52 and a secondary side cylinder 53, and these are communicated by a pair of pipes 54 and 55 provided on the upper and lower parts, respectively. A cathode chamber 56 is provided in the cylinder 52, and the cathode chamber 56 is formed of a porous electrically insulating material wall. In the cathode chamber 56, a cathode 57 is provided, and a liquid level detector 58 and a tube 59 for supplying an electrolyte into the cathode chamber 56 are provided. The cathode chamber 56 is connected to a gas cleaning tower 60 that cleans and releases gaseous substances generated at the cathode 57. Primary side cylinder 52
Rotates by the drive of the anode 62 and the motor 63,
A turbine 64 for stirring the solution mixture in the primary and secondary cylinders 52 and 53 is provided.

The secondary cylinder 53 is provided with a coil 65 for cooling the solution mixture, and is provided with a hardly soluble substance.
3 is provided with a supply funnel 66. Further, in the secondary side cylinder 53, a reaction termination detecting device 68, an introduction tube 69 for introducing AgO and HNO _{3 as} reactants, and 1
A device 70 for discharging a produced solution for stirring the secondary and secondary cylinders 52 and 53 is provided. A screen 61, which is a neutron repair material, is attached between the two cylinders 52, 53.

With such a structure, the electrolytic dissolving tank 51
Plutonium dioxide and neptunium dioxide to be dissolved are introduced from the funnel 66 into an electrolytic cell containing an aqueous nitric acid solution, and silver oxide is added to the solution. The turbine 64 stirs the solution around the anode 62 by rotating,
The solution mixture is transferred from the primary cylinder 52 to the secondary cylinder 53 via the communication pipe 54 along the arrow in the figure, and further to the secondary cylinder 53.
Can be circulated through the communication pipe 55 to the primary side cylinder 52.

The electrolytic dissolving tank 51 has a surface area of the anode 62,
Maintaining the current density in the cell at a constant value selected as a function of the silver concentration of the solution that oxidizes Ag ⁺ to Ag2 ⁺ at a rate substantially equal to the maximum possible regeneration rate of Ag2 ⁺ ions Thus, a potential difference is applied between the anode 62 and the cathode 57. Then, the plutonium dioxide and the neptunium dioxide are oxidized and dissolved in the solution containing Ag ²⁺ .

[0006]

However, since plutonium is handled, from the viewpoint of criticality control, the reaction takes place in a very limited space, such as a small-diameter cylindrical (pipe-shaped vessel) melting tank as described above. And promote the decomposition reaction. In the conventional apparatus, a small impeller pump or a propeller stirrer is installed as much as possible, and the solution in the tank is stirred, and at the same time, the anode, the cathode, and the diaphragm are provided in the same tube. In addition, the fluidity of the liquid decreases, and the maintenance becomes complicated. Also,
There is also a need for a small-diameter cylindrical dissolving tank in which a stirrer or the like cannot be installed in the same cylindrical tube. The present invention has been made in view of the above problems, and has as its object to provide a dissolving tank that can be reliably stirred with a simple structure in order to dissolve a hardly soluble substance that requires criticality management.

[0007]

In order to achieve the above object, a dissolving tank of the present invention has an inlet for a substance to be dissolved, a first tank for immersing an anode in a solution, and a diaphragm. A second tank for impregnating the enclosed cathode, and an upper part of the first tank and the upper part of the second tank which are in communication with each other to form a passage for the solution of the first tank to the second tank. The passage, the lower portion of the second tank and the lower portion of the second tank are communicated with each other, and the lower communication passage serving as a passage for the solution of the second tank to the first tank and the lower communication passage interposed in the lower communication passage. A circulation pump for sending the solution in the second tank to the first tank.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A dissolving tank according to an embodiment of the present invention will be described below with reference to FIG. FIG.
Shows a dissolution tank 1 of the electrolytic oxidation dissolution apparatus according to the present invention,
The dissolving tank 1 is a cylindrical primary cylinder 2 having a small diameter (first tank).
And a secondary cylinder (second tank) 3. These primary and secondary cylinders 2 and 3 are arranged so that the cylinder axes are vertical. The primary side cylinder 2 is provided with a chute 5 for introducing a hardly soluble nuclear fuel into the side cylinder 2 on a side wall, and an anode 4 immersed in a solution 12 at a lower portion. The secondary cylinder 3 has a diaphragm 6
And a cathode 7 immersed in a catholyte 13 provided in the diaphragm. The anode 4 is connected to the negative side of the DC power supply 10, and the cathode 7 is connected to the positive side of the DC power supply 10.

In the melting tank 1, a cooling jacket 16 for preventing a rise in the liquid temperature is provided on the outer periphery of the lower part of the primary cylinder 2, and the primary cylinder 2 and the secondary cylinder 3 are vertically arranged in a pair. The upper communication pipes 8 and 9 communicate with each other. In the dissolving tank 1, a circulation pump 11 is provided outside the cylinders 2 and 3 on the both sides. These lower communication pipes 14 are provided between the bottom of the secondary cylinder 3 and the circulation pump 11, and the other lower communication pipe is provided. Reference numeral 15 is provided near the anode 4 at the lower part of the side wall of the primary cylinder 2. The circulation pump 11 circulates the solution 12 from the secondary cylinder 3 to the primary cylinder 2 and stirs and homogenizes the solution 12.

Next, the operation of the melting tank in the present embodiment will be described. Primary and secondary cylinders 2 and 3 of melting tank 1
Into a solution (a nitric acid solution containing silver nitrate) and shoot 5
A poorly soluble nuclear fuel (solid). DC power supply 10
A voltage is applied between the anode 4 and the cathode 7 by the
It is about 0.1 to 1 A / cm ² . Under these conditions, Ag ⁺ ions in the solution are oxidized on the surface of the anode 4 and
g ²⁺ ions. Ag ²⁺ ions are strong oxidants. When the Ag ²⁺ ions come into contact with the surface of the poorly soluble substance, the poorly soluble substance is oxidized and dissolved by the Ag ²⁺ ions. The Ag ²⁺ ion, which was a strong oxidizing agent, is reduced as a result, and the same Ag ²⁺ ion as that previously existing in the solution 12 is obtained.
⁺ Ions. When the generated Ag ⁺ ions come into contact with the anode 4 under energization, they become Ag 2 ⁺ ions again and are regenerated. Such repetition makes it possible to electrically dissolve the poorly soluble substance.

However, the diffusion of ions in a stationary solution is slow at normal temperature, and the desired reaction does not occur unless the ions come into contact with the electrode or the dissolved target substance. Also, strong oxidants are unstable by themselves, react with other ions around them, and reduce themselves. In this case, even if the ions are electrically regenerated, there is a high possibility that the ions are not used for dissolving the target hardly soluble substance. Therefore, a circulation pump is used as a means for positively circulating and stirring the solution, thereby increasing the chance of efficiently contacting the electrically regenerated oxidizing agent with the target hardly soluble substance and shortening the dissolving time. Can be planned.

As described above, in the present embodiment, the oxidizing agent can be efficiently circulated and stirred by using the circulating pump. There is no need to dispose a turbine or the like in the side cylinder as in the related art. Further, a cooling jacket 16 is mounted outside the side tube 2 to cool the solution 12. Therefore, the diameter of both side tubes 2 and 3 can be reduced. As a result, the regenerated strong oxidizing agent can be brought into effective contact with the target hardly soluble substance without changing the shape of the melting tank in a limited space (critical dimension), and as a result of promoting the dissolution flow. , A hardly soluble substance or the like can be dissolved within a finite time.

Although the embodiment of the present invention has been described above, the present invention is, of course, not limited to this, and various modifications can be made based on the technical concept of the present invention. For example, in the above embodiment, the circulating pump 11
Although the secondary and secondary cylinders 2 and 3 are circulated and agitated, an ejector, an air wrist, and the like can be used in addition to the pump.

[0014]

As described above, according to the melting furnace of the present invention, the first tank in which the substance to be melted is introduced and the anode is immersed in the solution, and the cathode in which the cathode is surrounded by the diaphragm are immersed. Two tanks,
The upper part of the first tank and the upper part of the second tank are communicated with each other to form the first tank.
An upper communication path for allowing the solution in the tank to flow out to the second tank, a lower communication path communicating the lower parts of the first tank and the second tank, and a second communication path arranged in the lower communication path. Since a circulation pump for supplying the solution in the tank to the first tank is provided, the oxidizing agent can be efficiently circulated and stirred by using a pressure feeding device. Thereby, it is not necessary to change the shape of the melting tank in a limited space. In addition, as a result of promoting dissolution and flow, the regenerated strong oxidizing agent can effectively contact the hardly soluble substance when it is dissolved, and can dissolve the hardly soluble substance within a finite time.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a melting tank according to an embodiment of the present invention.

FIG. 2 is a conceptual diagram of a dissolving tank according to a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Dissolution tank 2 Primary side cylinder 3 Secondary side cylinder 4 Anode 5 Chute 6 Diaphragm 7 Cathode 8, 9 Upper communication pipe 10 DC power supply 11 Circulation pump 12 Solution 13 Catholyte 14, 15 Lower communication pipe 16 Cooling jacket

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Tadaaki Koga 5-1-1-16 Komatsu-dori, Hyogo-ku, Kobe City, Hyogo Prefecture Inside Shinryo High-Tech Co., Ltd.

Claims (1)

[Claims] 1. A first tank having an inlet for a substance to be dissolved and immersing an anode in a solution, a second tank immersing a cathode surrounded by a diaphragm, a first tank and a first tank. An upper communication passage communicating the upper portions of the two tanks and allowing the solution in the first tank to flow to the second tank; and a lower communication passage communicating the lower portions of the first and second tanks. And a pressurized liquid device disposed in the lower communication passage and for sending the solution in the second tank to the first tank.