JPS5885000A - Electrolytic decontaminating method for radioactively contaminated metal - Google Patents

Abstract

PURPOSE:To elute the surfaces of contaminated metals uniformly and efficiently by moving assembled cathodes consisting of plural cathodes provided with insulating spacers to the contaminated metal side of anodes and making the surfaces of the assembled electrodes coincident approximately with the shapes of the anodes. CONSTITUTION:Air 25 is blown into a piping 21 to pressurize and pack the air into the spacings 17 formed of bellows pipes 16. Electrodes 14 move together with spacers 15 to a contaminated metal 12 side by overcoming the tensile force of coil springs 20 and stops when the spacers 15 abut on the metal 12. At the point of this time, valves 22 are closed to stop blasting. If the air is blown into the spaces 17 formed of the pipes 16 in such a way, all the electrodes 14 can be disposed in the positions coinciding with the surface shape of the metal 12 via the spacers 15. An electrolyte 1 is filled only in the spaces 17 and is required in les amt. Thus, current density is made uniform with a less amt. of the electrolyte 1 and the effective electrolysis is accomplished.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a method for electrolyzing radioactively contaminated metal by immersing contaminated metal whose surface is contaminated with radioactive substances generated from equipment handling radioactive substances in an electrolytic solution as an anode, and eluting the contaminated portion by electrolytic action. Concerning the de-dyeing method.

When metal whose surface is contaminated with radioactive substances is immersed in a coffin to decontaminate the metal, as shown in Fig. 1, the electrolytic solution 1 is placed in the electrolytic cell 2, and the contamination is connected to the electrolyte 1. The metal 4 is connected to the anode of the DC voltage #5, and the contaminated portion of the contaminated metal is eluted into the electrolytic solution 1 by electrolytic action, thereby carrying out electrolytic de-dying.

In such a conventional method, when the contaminated gold j 144 is small compared to the electrolytic bath 2, or when the contaminated metal 4 has a complicated shape, the amount of electrolyte becomes large compared to the volume of the contaminated metal. As a result, the amount of used electrolytic solution increases significantly, and its processing is not only troublesome because it contains a large amount of radioactive material, but also the amount of secondary waste associated with this becomes enormous. Further, since the electrode 3 connected to the cathode is usually formed in a flat plate shape,
If the contaminated metal has a complex surface shape, during electrolytic operation,
Since the current density is non-uniform, uniform and normal elution cannot be obtained at the bottom of the contaminated metal, making it impossible to carry out efficient electrolytic de-staining. In order to deal with problems such as oxidation, it may be possible to create an electrode according to the shape of the contaminated metal surface. (Me#) Also, production costs will be incurred.

Regardless of the size or shape of the radioactively contaminated metal,
It is an object of the present invention to provide a method for dedying 1f radioactively contaminated metals, which can carry out efficient electrolytic dedying with a small amount of electrolyte. .

The present invention uses a plurality of cathodes, each of which is provided with an insulating spacer protruding on the side facing the positive electrode, for an anode made of a contaminated metal whose surface is contaminated with radioactive material generated from radioactive material handling equipment. It is supported by a stretchable elastic body housed in a cavity whose periphery is hermetically connected to the inner surface of the electrolytic cell, and during electrolytic dedying operation, the collective cathode consisting of the plurality of cathodes is moved toward the anode side, and the collective cathode is moved to the anode side. By arranging the electrode surface to approximately correspond to the shape of the surrounding surface of the anode, it is possible to respond to changes in the shape of the contaminated metal, and to adjust the amount of electrolyte to a volume corresponding to the outer periphery of the contaminated metal outside the cavity. This is the amount to be used.

Embodiments of the present invention will be described below based on the drawings.゛In Fig. 2, a contaminated metal 12 is placed in an electrolytic cell 11,
This contaminated metal 12 is connected to the anode of a power source 13.

In addition, an insulating spacer 15 is provided that protrudes from the surface 11 of the electrode 14 facing the contaminated metal 12, and a rubber bellows tube 16 is provided between the electrode 14 and the side wall of the electrolytic cell 11. A hollow cylinder portion 17 is formed.

As described above, FIG. 2 shows the arrangement of the electrodes during electrolytic operation. Next, the arrangement of the electrodes will be explained in more detail with reference to FIG. In FIG. 3, an insulating spacer 15 is formed to have an H-shaped cross section, and an electrode 14 is fitted within this spacer 15. A hole is drilled in the center of the spacer 15, and a conductive rod P18 is inserted through the hole and connected to the electrode 14. The other end of the rod 1'8 is slidably provided in a hole in an insulating member 19 provided on the side wall of the electrolytic cell 11. Further, a bellows tube 16 made of rubber is provided between one end of the spacer 15 and the side wall of the electrolytic cell 11, and the spacer 15 and the insulating member 1 are connected inside the bellows tube 16.
A coil nose 20 is interposed between the two. Bellows pipe 16
The hollow cylinder portion formed by this is communicated with the outside through a pipe 21, and a knob 22 is interposed in the middle of this pipe 21.

Further, one end of the rod 18 is connected via an electric wire 23 to the cathode of a power source 13 as shown in FIG.

Note that a switch 24 is interposed in the middle of the electric wire @23.

In the electrolytic dedying apparatus having such a configuration, the noservo 22 is opened, air is blown into the pipe 21, and the hollow cylindrical portion 17 formed by the bellows pipe 16 is filled with air under pressure. As a result, the electrode 14, together with the spacer 15, resists the tensile force of the coil head 20, causing the electrode 14 to become contaminated with gold! ! 1
It moves to the t12 side and stops when the spacer 15 comes into contact with the contaminated metal. At this point, tighten the knob 22 and
Stop the ventilation in step 5. By blowing air into the hollow cylindrical portion 17 formed by each bellows tube 16, all the electrodes are arranged at positions corresponding to the surface shape of the contaminated metal 12 via the spacers 15t. Therefore, each electric 1k1
The arrangement state of the end electrodes formed by the electrodes 4 corresponds approximately to the shape of the bottom surface of the contaminated metal 12, as shown by the broken line 26 in FIG. Furthermore, the electrolytic solution 1 is located outside the contaminated metal 12 and forms a hollow cylindrical portion 17 formed by the bellows tube 16.
It is filled only externally. Therefore, by using a small amount of electrolyte, the current density can be made uniform and efficient electrolysis can be carried out. At the end of the electrolytic dedying operation, when the 9-lube 22 is opened and the air in each cavity 17 is removed, the electrode 14 is moved toward the side wall of the electrolytic cell 11 by the restoring force of the coil nozzle 20.

Next, the contaminated metal 12 is taken out from the electrolytic bath 11 and prepared for the next electrolytic de-dying of the contaminated metal.

In this example, each rod r18 connected to the electrode 14
are connected to electric wires 23 each having a switch 24 interposed therebetween, so that the surface of the contaminated metal 12 can be selectively de-dyed by operating each switch 24.

FIG. 4 is a main part configuration diagram showing another embodiment of the present invention, and the difference from the embodiment shown in FIG. 3 is that the rubber bellows tube 2
7 is stretched between each spacer 15 and is stretched between the spacer 15 and the -' electrolytic cell 1. Therefore, in this embodiment, a plurality of rods 18 and a coil nose 20 are built into one hollow cylinder part formed by the bellows pipe 27, and a valve 22 is installed in this hollow cylinder part.
Nine pipes 21 are connected to each other by interposing.

In the electrode dyeing apparatus having such a configuration, by introducing air into the hollow cylinder portion from the pipe 21, 11! Move several electrodes 14 to the contaminated metal 12,
After the electrolytic dedying operation is completed, the plurality of electrodes 14 can be simultaneously moved toward the side wall of the electrolytic cell 11 by drawing out air from the pipe 21.

In this embodiment, compared to the embodiment shown in FIG. 3, the volume of electrolyte 1 can be reduced, and the number of pipes 21 and knobs 22 can be reduced, so that it is easier to install these devices. Since the space can be reduced, electrostatic dedying can be performed with a simple device.

In the present invention, the coil spring 20 may be a string-like member made of an elastic body such as rubber. In short, any material may be used as long as it has the function of moving the electrode 14 toward the side wall of the electrolytic cell 11 with restoring force when the fluid pressure is released. Further, instead of the bellows tubes 16 and 27, a flexible sheet having durability against the electrolyte 1 may be used. Also, empty cylinder part 1
7 may be filled with hydraulic pressure in addition to air pressure. In short, all you have to do is apply fluid pressure.

As described above, according to the present invention, the cathode can be placed in a state that approximately corresponds to the peripheral surface shape of the anode made of a contaminated metal, so that the current density can be made uniform, and the current density can be uniformized. Inside the hollow cylinder part is an electric 'N41&.

Since there is no intervention, highly efficient electrolytic de-staining can be performed with a small amount of electrolyte.

[Brief Description of the Drawings] Fig. 1 is a block diagram showing a conventional electrode dyeing method, Fig. 2 is an overall block diagram showing an embodiment of the present invention, and Fig. 3 is a detailed structure of main parts of Fig. 2. 4 are detailed configuration diagrams of main parts showing other embodiments of the present invention. DESCRIPTION OF SYMBOLS 11... Electrolytic tank, 12... Contaminated metal, 14... Electrode, 15... Spacer, 16... Bellows tube, 17...
・Empty cylinder part, 18...Rotsu P119...Insulating member, 20...Coil nose, 22...Valve, 23.
...Wire, 24...Switch, 25...Air. Agent Tatsuyuki Unuma (and 2 others)

Claims (4)

[Claims] (1) In a method for electrolytically decontaminating radioactively contaminated metals, a contaminated metal whose surface is contaminated with radioactive substances generated from equipment handling radioactive substances is immersed as an anode in an electrolytic solution, and the contaminated portion is eluted by electrolytic action. On the other hand, a plurality of cathodes each having an insulating spacer protruding from the surface facing the anode are each connected to the inner surface of the electrolytic cell by an expandable supporting member housed in a hollow cylindrical portion that is hermetically connected to the periphery. and moving the collective cathode consisting of the plurality of sheets of yomi toward the anode side during the electrolytic dedying operation, so that the surface of the collective electrode is placed in a one-plane state that approximately corresponds to the shape of the peripheral surface of the anode. A method for electrolytic de-dying of radioactively contaminated metals. (2) The method for electrolytic decontamination of radioactively contaminated metals according to item 1, wherein the hollow cylinder portion whose periphery is hermetically connected to the inner surface of the electrolytic cell and each elastic body supporting each cathode are respectively provided. (3) A hollow cylinder whose periphery is hermetically connected to the inner surface of the electrolytic cell is provided so as to integrally cover a plurality of elastic bodies that support each cathode, respectively. F! '# Scope of Requirements The method for electrolytic de-dying of radioactively contaminated metals according to item 1. (4) The elastic body is made of a coil spring.9 During the electro-de-dying operation, a gas such as air is pressurized into the cylinder, and after the electro-de-dying operation is completed, the restoring force of the coil spring moves the collective cathode to the anode side. A method for electrolytic decontamination of radioactive pollutants according to claim 1, in which the electrodes are separated.