JP2002357695A - Decontamination method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a chemical decontamination method and device capable of repeating the decontamination of an object to be decontaminated without decomposing a decontamination solution by providing a reducing agent storage tank and an oxidizer storage tank in order to solve the problem in the conventional decontamination of the object that chemical decontamination takes a long time because oxidative decontamination, oxidative destruction, reductive decontamination, reducing agent decomposition and washing are required every cycle. SOLUTION: This chemical decontamination device comprises the oxidizer storage tank for storing an oxidizer decontamination solution in a decontamination tank after oxidative decontamination tank, the reducing agent tank for storing the reducing agent decontamination solution in the decontamination tank after reductive decontamination, and a transfer pump for mutually transferring the decontamination solution between the decontamination tank and the storage tanks, so that the decontamination solution can be repeatedly used.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an RI facility or a nuclear facility, and more particularly to a method for chemically removing a radioactive substance from the surface of a large number of objects to be decontaminated with a metal member contaminated with the radioactive substance. And its device.

[0002]

2. Description of the Related Art As a conventional technique relating to chemical decontamination of metal waste, for example, Japanese Patent Laid-Open Publication No.
No. 53496 is disclosed. The disclosed content is shown in FIG. FIG. 6 shows a configuration of a conventional chemical decontamination apparatus. The chemical decontamination method in the conventional configuration will be described with reference to these drawings.

[0005] FIG. 5 is a view showing a structure of a decontamination target in a decontamination tank.
The operation to return the decontamination liquid in the decontamination tank to the storage tank is specified by starting or stopping the pump, switching between the decontamination liquid supply line and circulation line, or supplying and stopping air, nitrogen, and inert gas. This is to prevent the concentration of the decontamination solution from decreasing repeatedly every time.

FIG. 5 shows a chemical decontamination apparatus provided with a decontamination tank 2 and a storage tank 3 for storing a chemical decontamination liquid. In this configuration, the decontamination liquid 54 is transferred from the decontamination tank 2 to the storage tank 3, a solid-liquid separation operation for separating the decontamination liquid and the object 1 to be decontaminated, and the decontamination liquid is transferred from the storage tank 3 to the decontamination tank 2. By repeatedly performing a solid-liquid contact operation of bringing the decontamination liquid and the decontamination target 1 into contact with each other, it is possible to prevent a reduction in the dissolution rate and reduce the radioactivity level in a short time. 1 is an object to be decontaminated, 12 is a pump, 55 is a supply line, 57 is a supply valve, 58 is a circulation valve, 59 is a drain valve, 56 is an overflow line, and 9 is a heater (heater).

FIG. 6 shows the configuration of another chemical decontamination apparatus as a second prior art. In this configuration, a decontamination target 1 requiring decontamination is installed in a decontamination tank 2. The temperature in the heater 9 is raised while circulating the liquid in the chemical decontamination apparatus with the circulation pump 6. An oxidizing agent is injected from the chemical inlet 13 of the chemical input device, and the liquid in the chemical decontamination device is converted to an oxidative decontamination liquid. By maintaining this state for several hours, chromium oxide and the like taken into the oxide film of the object 1 to be decontaminated are dissolved.

Thereafter, a reducing agent is introduced into the oxidative decontamination solution from the chemical inlet 13 to decompose the oxidative decontamination solution and convert the liquid in the chemical decontamination apparatus into a reduction decontamination solution. By maintaining this state for about 10 hours, iron oxide and the like, which are the main components of the oxide film of the object 1 to be decontaminated, are dissolved. At this time, the reduced decontamination liquid is passed through the cationic resin tower 8 to remove metal ions dissolved by the reduced decontamination liquid and metal ions generated by decomposition of the oxidized decontamination liquid.

Then, the reducing and decontaminating solution is passed through the reducing agent decomposing device 10 while the decomposing agent is injected from the decomposing agent injecting device 11 (the valves V18 and V19 are opened) to decompose the reducing and decontaminating solution. When the reduction decontamination liquid decomposition is completed, the mixed bed resin tower 7
Water through the valve (valve V14, V15 open), decontamination target 1
Is washed. The chemical decontamination operation as described above is defined as one cycle, and is repeated for about two to several cycles depending on the degree of contamination of the decontamination object 1, and the chemical decontamination is completed. V1, V5
V10, V14 to V19, and V27 to V30 are control valves that are opened and closed as needed.

For example, assuming that there are four objects to be decontaminated, a heating time is 2 hours, an oxidizing decontamination time is 3 hours, an oxidizing agent decomposing time is 1 hour, a reducing decontaminating time is 6 hours, and a reducing agent decomposing time is 6 hours. Table 1 shows an example showing the steps of chemical decontamination in a case where the time is 9 hours and the washing is 6 hours, and two cycles are repeated for one decontamination object.

[0009]

[Table 1]

[0010] As shown in Table 1, it can be seen that it takes about 50 hours to decontaminate one decontamination object. Since the decontamination after the second decontamination target cannot be started until the decontamination of the previous decontamination target is completed, only one decontamination target can be decontaminated about every 50 hours, and four It takes about 200 hours to decontaminate the object to be decontaminated. As a countermeasure, it is conceivable to increase the size, increase the number, or improve the performance of the reducing agent decomposition apparatus to shorten the reducing agent decomposition time. However, when the size of the equipment is increased or the number of the equipment is increased, it is necessary to increase the installation space of the apparatus, and furthermore, it is necessary to increase the circulation flow rate. In order to improve the performance of the reducing agent decomposition apparatus, it is necessary to perform various tests to develop the apparatus, which takes time.

[0011]

In the first prior art, only one storage tank 3 is provided. An operation method for chemically decontaminating an object to be decontaminated using two types of decontamination liquids, namely a reduction decontamination liquid and an oxidative decontamination liquid, is not shown. Also, even after the chemical decontamination of the decontamination target has been completed,
Since the decontamination liquid remains attached to the decontamination target, it is difficult to dispose of the decontamination target in this state,
Removal of the decontamination liquor is required, but no instructions are given. Furthermore, it is necessary to treat the used decontamination solution by a method such as decomposition, but the method is not disclosed.

In the second prior art, since it is necessary to perform oxidative decontamination, oxidizing agent decomposition, reduction decontamination, reducing agent decomposition and cleaning for each cycle, it takes a long time to perform chemical decontamination. There is a problem.

Further, since the oxidizing agent and the reducing agent are decomposed in each cycle, it is necessary to perform oxidative decontamination or reduction decontamination with a new chemical in the next step, which requires a large amount of chemical. For example, when the amount of the oxidative decontamination solution is 3 m ³ and 200 ppm of potassium permanganate is used as the oxidative decontamination solution, potassium permanganate is about 0.6 k per cycle.
g is required. Further, it is assumed that the amount of the reduction decontamination solution is 3 m ³ , and that oxalic acid is 2000 ppm as the reduction decontamination solution. When potassium permanganate in the oxidative decontamination solution is decomposed with oxalic acid, oxalic acid is reduced to about 7 per cycle. It requires .4 kg.

[0014] Therefore, for one decontamination object, 2
Assuming that cycle decontamination is performed, potassium demanganate is about 4.8 kg to decontaminate four decontamination objects.
And about 59.2 kg of oxalic acid. As a countermeasure, it is conceivable to lower the chemical concentration, but lowering the chemical concentration causes a decrease in the decontamination effect.

Further, since the metal ions generated by the decomposition of the oxidizing agent are adsorbed on the cationic resin, the load on the cationic resin is increased. For example, when the surface area of one decontamination target is 40 m ² , the amount of the oxidative decontamination solution is 3 m ³ , and 200 ppm of potassium permanganate is used as the oxidative decontamination solution,
The loading on the cationic resin of potassium ions and manganese ions generated by the decomposition of the oxidizing agent accounts for about 35% of the total loading of the cationic resin. For this reason, it is necessary to increase the amount of the cationic resin, and there is a problem that the capacity of the equipment is increased.

An object of the present invention is to efficiently remove a radioactive substance from a surface in a relatively short time when a large number of metal members are contaminated with the radioactive substance.
It is an object of the present invention to provide a chemical decontamination method and apparatus capable of reducing the amount of chemicals used and reducing the amount of resin that becomes secondary waste.

[0017]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention provides a reducing agent storage tank and an oxidizing agent storage tank, and supplies a decontamination solution from the decontaminating tank to the reducing agent storage tank or the oxidizing agent. Chemical decontamination that can be repeated multiple times without decomposing the decontamination solution by transferring to the storage tank and transferring from the reducing agent storage tank or oxidant storage tank to the decontamination tank. Dyeing method and apparatus. Specific means are as follows.

In the chemical decontamination method in which an object to be decontaminated is placed in a decontamination tank and decontaminated, an oxidative decontamination agent is charged into a circulation path in which the decontamination tank, a heater and a circulation pump are connected by a circulation pipe. Then, the object to be decontaminated is oxidized and decontaminated using the oxidative decontamination liquid filled in the circulation path, and after the oxidative decontamination, the oxidative decontamination liquid is transferred to an oxidizing agent storage tank, and then oxidized. When performing dyeing, the oxidative decontamination liquid in the oxidant storage tank is transferred to the circulation path, and the object to be decontaminated is oxidized and decontaminated using the oxidization decontamination liquid filled in the circulation path. It is characterized by the chemical decontamination method.

In the chemical decontamination method in which an object to be decontaminated is placed in a decontamination tank and decontaminated, a reducing decontamination agent is introduced into a circulation path in which the decontamination tank, a heater and a circulation pump are connected by a circulation pipe. Then, the object to be decontaminated is reduced and decontaminated using the reduced decontamination liquid filled in the circulation path, and after the reduction decontamination, the reduced decontamination liquid is transferred to a reducing agent storage tank, and then reduced and decontaminated. When performing dyeing, the reduction decontamination liquid in the reducing agent storage tank is transferred to the circulation path, and the object to be decontaminated is reduced and decontaminated using the reduction decontamination liquid filled in the circulation path. It is characterized by the chemical decontamination method.

In the chemical decontamination method in which an object to be decontaminated is placed in a decontamination tank and decontaminated, pure water is supplied to a first circulation path in which the decontamination tank, a circulation pump and a heater are connected by a circulation pipe. The pure water is circulated by the circulation pump, the pure water is heated by the heater, and when the pure water reaches a predetermined temperature, the oxidative decontamination agent is supplied to the first circulation path. Throwing in, deoxidizing the object to be decontaminated by holding the oxidative decontamination liquid filled in the first circulation path at a predetermined concentration for a predetermined time, and transferring after the oxidative decontamination. The oxidative decontamination liquid is transferred to an oxidant storage tank by a pump, and a second circulation path in which the decontamination tank, the circulation pump, the heater, and the cationic resin tower are connected by a circulation pipe is filled with pure water. Circulating the pure water by the circulation pump, When the pure water reaches a predetermined temperature, a reducing decontamination agent is supplied to the second circulation path, and the reduced decontamination liquid filled in the second circulation path is predetermined. Reduced decontamination of the object to be decontaminated by holding the concentration for a predetermined time, after the reduction decontamination, transfer the reduced decontamination solution to the reducing agent storage tank by the transfer pump,
The decontamination is performed by filling a third circulation path connecting the decontamination tank, the circulation pump, the heater, and the mixed-bed resin tower with a circulation pipe with pure water, and circulating the pure water by the circulation pump. It is characterized by the chemical decontamination method of cleaning the object.

In a chemical decontamination apparatus including a decontamination tank, a pump, a heater, a mixed-bed resin tower, a cationic resin tower, a reducing agent decomposing device, and a decomposed chemical injection device, the decontamination tank is used for oxidative decontamination. An oxidizing agent storage tank for storing the oxidized decontamination liquid obtained, a reducing agent storage tank for storing the reduced decontamination liquid used for reduction decontamination in the decontamination tank, the decontamination tank and the oxidizing agent storage tank or the It is characterized by a chemical decontamination apparatus equipped with a transfer pump for mutually transferring a decontamination liquid between the reducing agent storage tank.

In a chemical decontamination apparatus for decontaminating an object to be decontaminated in a decontamination tank, a decontamination tank, a circulation pump and a heater for heating circulating water are connected by a circulation pipe. 1
A circulation path, an apparatus for charging the oxidative decontamination agent to the first circulation path when the circulating water is heated by the heater and reaches a predetermined temperature, the decontamination tank after oxidative decontamination, and A transfer pump for transferring the oxidative decontamination solution in the circulation pipe to the oxidant storage tank, a second circulation path configured by adding a cationic resin tower on the first circulation path, A device for circulating with a pump, heating with the heater, and supplying a reducing agent to the second circulation path when pure water reaches a predetermined temperature, the decontamination tank and the circulation after reduction decontamination A reducing agent storage tank that transfers and stores the reduced decontamination liquid in the pipe by the transfer pump; and a third circulation path that forms a circulation cleaning path by adding a mixed-bed resin tower on the first circulation path. And a chemical decontamination device that performs decontamination and cleaning.

[0023] In the chemical decontamination method in which the object to be decontaminated is placed in a decontamination tank and decontaminated, the object to be decontaminated using an oxidized decontamination liquid filled in a first circulation path including the decontamination tank. After the oxidative decontamination, the oxidative decontamination liquid is transferred to an oxidizing agent storage tank, and the decontamination is performed using a reduced decontamination liquid filled in a second circulation path including the decontamination tank. After subjecting the object to reduction decontamination and the reduction decontamination, the reduction decontamination liquid is transferred to a reducing agent storage tank,
A chemical decontamination method is characterized in that the decontamination target is washed using water filled in a third circulation path including the decontamination tank.

In a chemical decontamination apparatus for performing decontamination by placing an object to be decontaminated in a decontamination tank, a first circulation path including the decontamination tank and a circulation pump; An oxidizing agent storage tank for storing the oxidative decontamination solution in the first circulation path, a second circulation path including the decontamination tank, the circulation pump, and the cationic resin tower, and after reduction decontamination by the circulation path. A chemical comprising a reducing agent storage tank for storing the reduced decontamination liquid in the second circulation path, and a third circulation path for cleaning including the decontamination tank, the circulation pump, and the mixed-bed resin tower; The decontamination equipment is unique.

A decontamination tank for performing oxidative decontamination and reductive decontamination of an object to be decontaminated, a circulation pipe for circulating a decontamination solution in the decontamination tank, an oxidative decontamination agent and reductive decontamination A chemical inlet for charging the agent into the circulation pipe, and an oxidizing agent storage tank that stores an oxidative decontamination solution used for oxidative decontamination in the decontamination tank,
A chemical decontamination apparatus is characterized by comprising a reducing agent storage tank for storing a reduced decontamination solution used for reduction decontamination in the decontamination tank.

[0026]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. FIG. 1 shows a configuration example of the chemical decontamination apparatus of the present invention. The chemical decontamination apparatus of the present invention comprises a decontamination tank 2, a reducing agent storage tank 3, an oxidizing agent storage tank 4, and a circulation pipe.
The circulation pipe is provided with a circulation pump 6, a mixed-bed resin tower 7, a cationic resin tower 8, a heater 9, a reducing agent decomposer 10, a decomposed chemical injector 11, and a chemical inlet 13. Further, a transfer pump 12 is provided in a pipe connecting the circulation pipe with the reducing agent storage tank 3 and the oxidant storage tank 4.

The object 1 to be decontaminated is defined as one cycle in which the steps of oxidative decontamination with the oxidative decontamination solution, reduction and decontamination with the reduced decontamination solution, and cleaning of the object 1 are performed in the decontamination tank 2. Usually, two to several cycles are repeated. In addition, depending on the form of the oxide film formed on the object 1 to be decontaminated, only one cycle may be performed,
There may be several cycles.

In this embodiment, the first cycle is performed in the following order.

(1) The object 1 to be decontaminated is set in the decontamination tank 2, and the inlet / outlet valves V1, V10 of the decontamination tank 2, the inlet / outlet valves V6, V5 of the circulation pump 6, the resin tower 7, and the cationic resin tower. 8, bypass valves V7 and V8, and the bypass valve V of the reducing agent decomposition device 10
After opening the valve 9, the valve V30 of the pure water facility 40 is opened,
The decontamination tank 2 and the circulation pipe are filled with pure water.

(2) Thereafter, the circulation pump 6 is started to perform a circulation operation of the pure water, and the temperature of the pure water is raised by using the heater 9.

(3) When the temperature is raised to a predetermined temperature, the valve V2
7 is opened, and an oxidative decontamination agent is injected from the chemical inlet 13 of the chemical injection device to obtain an oxidative decontamination liquid having a predetermined oxidant concentration. This solution is used for oxidative decontamination. By maintaining this state for several hours, chromium oxide and the like taken into the oxide film of the object 1 to be decontaminated can be dissolved. On this occasion,
Efficient oxidative decontamination by properly setting in advance the temperature of pure water when adding an oxidative decontamination agent, the concentration of oxidative decontamination solution and the oxidative decontamination time when performing oxidative decontamination Can be. The temperature of the pure water, the concentration of the oxidative decontamination solution, and the oxidative decontamination time are determined in advance so that the performance of oxidative decontamination can be sufficiently obtained. For example, when potassium permanganate is used as the oxidative decontamination agent, the temperature of pure water when the oxidative decontamination agent is introduced is about 90 ° C. in which the oxidative decontamination agent is easily dissolved, and the concentration of the decontamination solution is 20
0 to 300 ppm, and the oxidative decontamination time is about 4 to 6 hours.

(4) When the oxidative decontamination is completed, the inlet valves V20 and V21, the outlet valve V22 of the transfer pump 12, and the inlet valve V25 of the oxidizing agent storage tank 4 are opened. The transfer pump 12 is started to transfer the oxidative decontamination liquid held in the decontamination tank 2 and the circulation pipe to the oxidant storage tank 4 for storage and storage, and to empty the decontamination tank 2 and the circulation pipe. To When the transfer of the oxidative decontamination solution is completed, the inlet / outlet valve V22 of the transfer pump 12
V20, V21 and the inlet valve V25 of the oxidant storage tank 4 are closed.

(5) At the start of the reduction decontamination, water in the chemical decontamination equipment (in the decontamination tank and the circulation path) is converted into a reduction decontamination solution, as in the case of the oxidative decontamination. Door valves V1 and V10 of the decontamination tank 2 and door valves V6 and V of the circulation pump 6
5, mixed-bed resin tower 7 bypass valve V7, cationic resin tower 8
After opening the inlet / outlet valves V17 and V16 and the bypass valve V9 of the reducing agent decomposition device 10, the valve V30 of the pure water facility 40 is opened to fill the decontamination tank 2 and the circulation pipe with pure water.

(6) Thereafter, the circulation pump 6 is started, and
A circulation operation is performed while passing water through the cationic resin tower 8, and the temperature is raised using the heater 9. In addition, the bypass valve V8 of the cation resin tower 8 is closed or adjusted and opened, and the flow rate of water to the cation resin tower 8 is adjusted to a predetermined flow rate.

(7) After the temperature is raised to a predetermined temperature, V27
Is opened, and the reducing decontamination agent is injected from the chemical inlet 13,
Set to a predetermined reducing agent concentration. By maintaining this state for about 10 hours, iron oxide and the like, which are the main components of the oxide film of the object 1 to be decontaminated, are dissolved. At this time, since the reduction decontamination liquid is passed through the cation resin tower 8, the dissolved metal ions are removed by the reduction decontamination liquid. At this time, the efficiency of reduction decontamination can be improved by appropriately setting in advance the temperature of pure water when the decontamination agent is added, the concentration of the reduction decontamination solution and the time of decontamination when performing decontamination. Can do well. The temperature of the pure water, the concentration of the reduction decontamination solution, and the reduction decontamination time are determined in advance so that the performance of the reduction decontamination can be sufficiently obtained. For example, when oxalic acid is used as the reducing decontamination agent, the temperature of pure water when the reducing decontamination agent is introduced is about 90 ° C. at which the decontamination agent is easily dissolved, the concentration of the decontamination solution is 2000 ppm, Is about 8 to 10 hours.

(8) When the reduction decontamination is completed, the inlet valves V20 and V21, the outlet valve V22 of the transfer pump 12, and the inlet valve V24 of the reducing agent storage tank 3 are opened. The transfer pump 12 is started to transfer the reduced decontamination liquid held in the decontamination tank 2 and the circulation pipe to the reducing agent storage tank 3 and store the same, and empty the decontamination tank 2 and the circulation pipe. When the transfer of the reduced decontamination solution is completed, the inlet / outlet valves V22, V20, V
21 and the inlet valve V24 of the reducing agent storage tank 3 are closed.

(9) In cleaning the object 1 to be decontaminated,
The inlet / outlet valves V1, V10 of the decontamination tank 2, the inlet / outlet valves V6, V5 of the circulation pump 6, the inlet / outlet valves V15, V1 of the mixed-bed resin tower 7.
4. After opening the bypass valve V8 of the cationic resin tower 8 and the bypass valve V9 of the reducing agent decomposing device 10, V30 is opened to fill the decontamination tank 2 and the circulation pipe with pure water.

(10) Thereafter, the circulating pump 6 is started to perform a circulating operation while passing water through the mixed-bed resin tower 7 to wash the object 1 to be decontaminated. Remove at 7. In addition, the bypass valve V7 of the mixed-bed resin tower 7 is closed or adjusted and opened, and the flow rate of water to the mixed-bed resin tower 7 is adjusted to a predetermined flow rate. When the cleaning of the decontamination target 1 is completed, the inlet / outlet valves V22 and V21 of the transfer pump 12 and the inlet valve V29 of the drainage facility 45 are opened, and drainage is performed from the outlet side of the mixed-bed resin tower 7 to the drainage facility.

In this embodiment, the drainage is performed by using the transfer pump 12. However, when the drainage equipment and the drainage equipment inlet valve 29 are provided so that the drainage can be performed using gravity, the transfer pump is used. It is not necessary to use 12.
Further, in this embodiment, the circulation path is formed by connecting the decontamination tank 2, the circulation pump 6, and the heater 9 with the circulation pipe, but the heating is performed by using the decontamination tank having the built-in heater. A similar effect can be obtained even if a circulation path is formed by connecting the decontamination tank containing the vessel and the circulation pump 6 by a circulation pipe. Further, in this embodiment, the circulation path is the heater 9
However, if sufficient decontamination performance can be obtained without using the heater 9, the heater 9 may be removed from the circulation path.

The oxidative decontamination, reductive decontamination and washing according to the above-described method are defined as the first cycle. In the second cycle, decontamination is performed using the oxidative decontamination solution and the reductive decontamination solution used in the first cycle.

In the oxidative decontamination in the second cycle, oxidative decontamination is performed using the oxidative decontamination solution stored in the oxidant storage tank 4. The second cycle is performed in the following order.

(1) The outlet valve V3 of the oxidizing agent storage tank 4, the inlet / outlet valves V23 and V20 of the transfer pump 12, the outlet valve V6 of the circulation pump 6, the bypass valves V7 and V8 of the hotbed resin tower 7 and the cationic resin tower 8, Bypass valve V of reducing agent decomposition device 10
9 and the inlet valve V10 of the decontamination tank 2 are opened, and the transfer pump 1
2 is started, and the oxidative decontamination liquid stored in the oxidant storage tank 4 is transferred to the decontamination tank 2. By performing this operation, the decontamination tank 2 and the circulation pipe can be filled with the oxidative decontamination liquid.

(2) Thereafter, the circulation pump 6 is started to perform a circulation operation, and oxidative decontamination is performed as in the first cycle.
If the temperature has been reduced while the oxidizing agent storage tank 4 is storing the oxidative decontamination solution, the temperature is increased by the heater 9. In addition, when the oxidizing agent concentration has decreased, V27
Is opened, and an oxidizing agent is additionally charged from the chemical inlet 13 to obtain a decontamination liquid having a predetermined concentration.

(3) When the oxidative decontamination is completed, the oxidative decontamination solution is moved from the decontamination tank 2 to the oxidant storage tank 4 and stored in the same manner as in the first cycle. In the reduction decontamination of the second cycle, the reduction decontamination is performed using the reduction decontamination liquid stored in the reducing agent storage tank 3.

(4) The outlet valve V2 of the reducing agent storage tank 3, the inlet / outlet valves V23 and V20 of the transfer pump 12, the outlet valve V6 of the circulation pump 6, the bypass valve V7 of the mixed bed resin tower 7, and the inlet / outlet of the cationic resin tower 8. Valves V17, V16, reducing agent decomposition device 10
By opening the bypass valve V9 and the inlet valve V10 of the decontamination tank 2, the transfer pump 12 is started to transfer the reduced decontamination liquid stored in the reducing agent storage tank 3 to the decontamination tank 2. By performing this operation, the decontamination tank 2 and the circulation pipe can be filled with the reduced decontamination liquid.

(5) Thereafter, the circulation pump 6 is started, and
The circulation operation is performed while passing water through the cationic resin tower 8, and the first
Perform reductive decontamination as in the cycle. When the temperature has been reduced while the reducing decontamination liquid is stored in the reducing agent storage tank 3, the temperature is increased by the heater 9. If the concentration of the reducing agent has decreased, V27 is opened, and a reducing agent is additionally introduced from the chemical inlet 13 to obtain a decontamination liquid having a predetermined concentration.

(6) After the reduction decontamination is completed, the reduced decontamination liquid is moved from the decontamination tank 2 to the reducing agent storage tank 3 and stored in the same manner as in the first cycle. The cleaning of the object 1 to be decontaminated is the same as the cleaning method in the first cycle.

The oxidative decontamination and reductive decontamination after the third cycle are the same as those in the second cycle. When the cleaning of the decontamination target 1 is completed, the decontamination target 1 is taken out of the decontamination tank 2.
At this time, since cleaning water may adhere to the surface of the decontamination target 1, it is desirable to remove the cleaning water by air blowing or wiping the decontamination target 1. When air blow is performed on the decontamination target 1, a spray nozzle for air blow is provided in the decontamination tank 2 to prevent the washing water from being scattered in an uncontrolled location, and air is blown in the decontamination tank 2. It is desirable to blow.

When there are a plurality of objects to be decontaminated, decontamination after the second object to be decontaminated is performed in the same manner as in the second cycle of the first object to be decontaminated. When a series of decontamination is completed, the decontamination solution is decomposed. The decomposition of the oxidative decontamination solution is performed by mixing the oxidative decontamination solution and the reduction decontamination solution.

That is, the inlet / outlet valve V of the reducing agent storage tank 3
2, V11, inlet / outlet valves V23, V2 of the transfer pump 12
0, the outlet valve V6 of the circulation pump 6, the bypass valves V7 and V8 of the hotbed resin tower 7 and the cationic resin tower 8, and the bypass valve V9 of the reducing agent decomposition device 10 are opened, and the transfer pump 1 is opened.
2, the reducing decontamination liquid stored in the reducing agent storage tank 3 is supplied into the circulation pipe, and the circulation pump 6 is started to perform the circulation operation.

Thereafter, the access valves V3 and V3 of the oxidant storage tank 4
12 is opened, the reduced decontamination solution and the oxidized decontamination solution are simultaneously sucked, and the reduced decontamination solution and the oxidized decontamination solution are mixed. The mixed liquid is returned to the reducing agent storage tank 3 and the oxidant storage tank 4 via the heater 9. In addition, by raising the temperature using the heater 9, the decomposition of the oxidizing agent can be promoted. The decomposition of the oxidative decontamination solution is not limited to the above-described operation method, as long as it can be mixed with the reduction decontamination solution.

After the decomposition of the oxidative decontamination solution components is completed, the reduction decontamination solution components in the mixed solution are decomposed. Decomposition of the reduced decontamination liquid component in the mixed solution is performed using a reducing agent decomposing device 10 and a decomposed chemical injection device 11. That is, the inlet / outlet valves V17 and V16 of the cation resin tower 8 are opened, and the bypass valve V8 is closed or adjusted and opened to flow a predetermined flow rate through the cation resin tower 8. Thereafter, the inlet / outlet valves V19 and V18 of the reducing agent decomposing device 10 are opened, and the bypass valve V9 is closed or adjusted and opened while the decomposed chemical is injected by opening the outlet valve V28 of the decomposed chemical injecting device 11 so that the mixture at a predetermined flow rate is supplied. Water is passed through the reducing agent decomposition device 10. In this way, by passing the mixed solution through the cationic resin tower 8, metal ions generated by the decomposition of the oxidative decontamination solution can be adsorbed and removed by the cationic resin. Further, by passing water through the reducing agent decomposing device 10 while injecting the decomposing chemical, the components of the reduced decontamination liquid in the mixed solution can be decomposed.

When the decomposition and decontamination solution components in the mixture have been decomposed to a predetermined concentration or less, the outlet valve V28 of the decomposition chemical injection device 11 is closed, and the bypass valve V9 of the reducing agent decomposition device 10 is opened. Inlet / outlet valves V19, V1 of the agent decomposition device 10
8 is closed to terminate the decomposition of the reducing agent.

Thereafter, the inlet / outlet valves V15,
V14 is opened, the bypass valve V7 is closed or adjusted and opened, the bypass valve V8 of the cationic resin tower 8 is opened, and the entrance / exit valve V17,
V16 is closed, and a mixture of a predetermined flow rate is passed through the mixed bed resin tower 7. After confirming that the water quality of the mixed solution satisfies the drainage standard, the inlet / outlet valves V22 and V21 of the transfer pump 12 and the inlet valve V29 of the drainage facility 45 are opened, and the transfer pump 12 is used to open the outlet of the mixed bed resin tower 7. Drain from side to drainage system.

In the present embodiment, the transfer pump 12 is used for drainage. However, when a drainage valve is provided so that drainage can be performed using gravity, the transfer pump 12 does not need to be used. . Further, in this embodiment, the circulation path is formed by connecting the decontamination tank 2, the circulation pump 6, and the heater 9 with the circulation pipe, but the heating is performed by using the decontamination tank having the built-in heater. The same effect can be obtained even if a circulation path is formed by connecting the decontamination tank containing the vessel and the circulation pump 6 by a circulation pipe. Further, in the present embodiment, the circulation path has the heater 9. However, if sufficient decontamination performance can be obtained without using the heater 9, the heater 9 may be removed from the circulation path. Good.

In the description of the above embodiment, the chemical decontamination apparatus is used to enter the reducing agent storage tank 3 or the oxidizing agent storage tank 4 from the inside of the chemical decontamination apparatus or from the reducing agent storage tank 3 or the oxidizing agent storage tank 4 to the inside of the chemical decontamination apparatus. The transfer of the decontamination solution is performed by using the transfer pump 12, but the transfer pump 12 is not always required. For example, if the reducing agent storage tank 3 or the oxidizing agent storage tank 4 is installed at a position lower than the chemical decontamination apparatus, the decontamination liquid is removed from the chemical decontamination apparatus by gravity in the reducing agent storing tank 3 or the oxidizing agent storage tank 4. It is possible to transfer to Also,
The decontamination liquid can be transferred from the reducing agent storage tank 3 or the oxidant storage tank 4 into the chemical decontamination apparatus by using the circulation pump 6 or by applying gas pressure to the storage tank. In short, it is only necessary that the decontamination liquid can be temporarily stored in the reducing agent storage tank 3 or the oxidizing agent storage tank 4, and the decontamination liquid can be transferred into the chemical decontamination apparatus as needed.

Further, in the present embodiment, the decontamination and cleaning are repeated with the steps of oxidative decontamination, reduction decontamination and washing as one cycle, but the decontamination with the steps of oxidative decontamination and reduction decontamination as one cycle. May be repeated and washing may be performed after decontamination is completed.

In this embodiment, the circulation path is filled with pure water. However, water may be used instead of pure water.

As described above, the decontamination liquid is transferred from the decontamination tank 2 to the reducing agent storage tank 3 or the oxidizing agent storage tank 4, or the decontamination liquid is decontaminated from the reducing agent storage tank 3 or the oxidizing agent storage tank 4. By transferring to the tank 2, there is no need to decompose the decontamination solution during the decontamination period. Also, when the number of decontamination objects 1 is large and decontamination needs to be performed a plurality of times, the decontamination solution can be used repeatedly, and the amount of decontamination agent and resin used is greatly increased. Can be reduced to

In the present embodiment, for example, assuming that there are four decontamination objects, decontamination of the decontamination object 1 is performed in the order of oxidative decontamination, reduction decontamination, and washing. The heating time was 2 hours, the decontamination solution transfer time was 1 hour, and the decontamination solution reheating time was 1 hour.
Time, oxidation decontamination time 3 hours, reduction decontamination time 6 hours,
Table 2 shows an example of the chemical decontamination process when the cleaning is performed for 6 hours and two cycles are repeated for one decontamination target.

[0061]

[Table 2]

As shown in Table 2, it takes about 40 hours to decontaminate one decontamination object. Since decontamination after the second decontamination target can be started from the time when decontamination of the previous decontamination target is completed, one decontamination target can be decontaminated approximately every 40 hours. It takes about 160 hours to decontaminate four objects to be decontaminated. That is, decontamination can be performed in about 80% of the time in the conventional example.

Furthermore, since both the oxidative decontamination liquid and the reduced decontamination liquid can decontaminate the object to be decontaminated without decomposing, the amount of chemicals used can be greatly reduced. For example, the amount of oxidative decontamination solution is 3 m ³ , and potassium manganate 2
If 00 ppm is used, about 0.6 kg of potassium permanganate is required per cycle.

When the amount of the reducing and decontaminating solution is 3 m ³ and oxalic acid of 2000 ppm is used as the reducing and decontaminating solution, about 6 kg of oxalic acid is required per cycle. Therefore, if it is assumed that 10% of the chemical is additionally introduced in each cycle, and that one cycle of decontamination is performed for one decontamination target, 4
In order to decontaminate one object to be decontaminated, potassium permanganate may be about 1.0 kg and oxalic acid may be about 10.2 kg. That is, in the present embodiment, the oxidizing agent is about 2
1% and the reducing agent may be about 17%, which can greatly reduce the amount of chemicals used. The effect of reducing the amount of chemical used increases as the number of cycles and the number of objects to be decontaminated increase.

Further, since the decomposition of the oxidizing agent is not required during the decontamination period, there is no need to adsorb and remove the metal ions generated by the decomposition of the oxidizing agent with the cation resin, and the load on the cation resin can be reduced. For example, using 200 ppm of potassium permanganate as an oxidative decontamination solution, replenishing 10% of potassium permanganate in each cycle, decomposing the oxidizing agent after decontamination of the four decontamination objects, and decomposing The manganese ion and potassium ion generated by the above are adsorbed and removed by the cation resin. When the surface area of one object to be decontaminated is 40 m ² and the amount of oxidative decontamination solution is 3 m ³ , the loading of potassium ions and manganese ions generated by decomposition of the oxidizing agent on the cationic resin is the total loading of the cationic resin. Of about 11%, and the load on the resin can be greatly reduced as compared with the conventional example. The effect of reducing the load on the resin increases as the number of cycles and the number of objects to be decontaminated increase.

FIG. 2 shows another embodiment of the present invention. In this embodiment, a spray device 14 is installed in the decontamination tank 2 so that the decontamination liquid or cleaning water can be sprayed on the decontamination target 1. In this embodiment, there is no need to submerge the object 1 to be decontaminated with a decontamination solution or washing water, and decontamination can be performed with a small amount of decontamination solution or washing water. 4 can be miniaturized, and the decomposition time of the decontamination solution can be reduced, the amount of the decontamination agent used can be reduced, and the load of the cationic resin can be reduced.

FIG. 3 shows still another embodiment of the present invention.
This embodiment is a case where a washing water storage tank 5 is further provided in the embodiment shown in FIG. Thus, by providing the washing water storage tank 5, the amount of washing water used can be reduced.

That is, when the cleaning of the object 1 to be decontaminated is completed in the first cycle, the inlet valves V20, V
21, the outlet valve V22, and the inlet valve V26 of the washing water storage tank 5 are opened. The transfer pump 12 is started to transfer the cleaning water held in the decontamination tank 2 and the circulation pipe to the cleaning water storage tank 5 to store the cleaning water and empty the decontamination tank 2 and the circulation pipe. When the transfer of the washing water is completed, the inlet / outlet valves V22, V20, V21 of the transfer pump 12 and the inlet valve V26 of the washing water storage tank 5 are closed. Thereafter, the second cycle of oxidative decontamination is performed as in the embodiment of FIG.

When the reduction decontamination in the second cycle is completed and the reduction decontamination liquid is transferred to the reducing agent storage tank 3, the object 1 to be decontaminated is washed. At the start of cleaning of the decontamination target 1, the cleaning water stored in the cleaning water storage tank 5 is transferred to the decontamination tank 2 and the circulation pipe. That is, the outlet valve V4 of the washing water storage tank 5, the inlet / outlet valves V23, V20 of the transfer pump 12,
Outlet valve V of circulation pump 6, Outlet valve V of mixed bed resin tower 7
15, V14, the bypass valve V8 of the cationic resin tower 8, the bypass valve V9 of the reducing agent decomposer 10 and the inlet valve V10 of the decontamination tank 2 are opened, the transfer pump 12 is started, and stored in the washing water storage tank 5. The used washing water is transferred to the decontamination tank 2. By performing this operation, the decontamination tank 2 and the circulation pipe can be filled with the oxidative decontamination liquid. After that Figure 1
The second cycle of cleaning is performed in the same manner as in the first embodiment.

FIG. 4 shows still another embodiment of the present invention.
In this embodiment, the decontamination tank 2 and its circulation pipe are
This is a case where two systems are provided. Thus, by providing two systems of the decontamination tank and the circulation pipe, the decontamination time can be further shortened (the valves of each system are a,
b).

That is, the objects 1a and 1b to be decontaminated are installed in the decontamination tanks 2a and 2b, respectively. The decontamination tank 2a and its circulation pipe are filled with an oxidative decontamination solution to perform oxidative decontamination. When the oxidative decontamination of the decontamination target 1a is completed, the transfer pump 12 is used to transfer the oxidative decontamination liquid into the decontamination tank 2b and its circulation pipe. Thus, the decontamination target 1b is oxidized and decontaminated in the decontamination tank 2b, and the decontamination tank 2a and its circulation pipe are emptied. After that, the decontamination tank 2a and its circulation pipe are filled with the reduced decontamination solution, and the decontamination target 1a is subjected to the reduction decontamination.

When the oxidative decontamination of the object 1b to be decontaminated is completed in the decontamination tank 2b, the oxidizing decontamination liquid is transferred to and stored in the oxidizing agent storage tank 4 using the transfer pump 12, and the decontamination tank 2b and its Empty the circulation piping.

When the reduction decontamination of the decontamination target 1a is completed in the decontamination tank 2a, the reduced decontamination liquid is transferred to the decontamination tank 2b and its circulation pipe by using the transfer pump 12. Thus, the decontamination target 1b is reduced and decontaminated in the decontamination tank 2b, and the decontamination tank 2a and the circulation pipe thereof are emptied. Thereafter, the decontamination target 2a can be cleaned by filling the decontamination tank 2a and its circulation pipe with cleaning water.

When the reduction decontamination of the decontamination target 1b is completed in the decontamination tank 2b, the reduced decontamination liquid is transferred to the reducing agent storage tank 3 by using the transfer pump 12, and stored in the decontamination tank 2b. Empty the circulation piping. Object 1a to be decontaminated in decontamination tank 2a
After the cleaning of the cleaning water is completed, the cleaning water is transferred to the decontamination tank 2b and the circulation pipe by using the transfer pump 12. Thereby, the decontamination target 1b is washed in the decontamination tank 2b,
Empty the decontamination tank 2a and its circulation pipe. Thereafter, using the transfer pump 12, the oxidizing decontamination liquid stored in the oxidizing agent storage tank 4 is transferred into the decontamination tank 2a and its circulation pipe,
A second cycle of oxidative decontamination is performed.

By operating as described above, decontamination in two decontamination tanks can be performed with one system of decontamination solution and washing water. Further, since the two objects to be decontaminated can be decontaminated at the same time, decontamination can be performed efficiently.

According to the present invention, a reducing agent storage tank and an oxidizing agent storage tank are provided, a decontamination solution is transferred from the decontaminating tank to the reducing agent storage tank or the oxidizing agent storage tank, and the decontamination liquid is transferred from the reducing agent storing tank or the oxidizing agent storage tank. By transferring to the decontamination tank, the decontamination liquid can be repeatedly used. Therefore, it is possible to perform decontamination in which the decontamination time is reduced, the amount of chemicals used is reduced, and the load on the resin is reduced.

[0077]

According to the present invention, a reducing agent storage tank and an oxidizing agent storage tank are provided, and a decontamination liquid is transferred from the decontamination tank to the reducing agent storage tank or the oxidizing agent storage tank. By transferring from the storage tank to the decontamination tank, the decontamination solution can be used repeatedly without decomposing, thereby shortening the decontamination time, reducing the amount of chemicals used, and reducing the resin load. it can.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a chemical decontamination apparatus according to one embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of another embodiment of the present invention.

FIG. 3 is a diagram showing a configuration of another embodiment of the present invention.

FIG. 4 is a diagram showing a configuration of another embodiment of the present invention.

FIG. 5 is a diagram showing a configuration example of a conventional chemical decontamination apparatus.

FIG. 6 is a diagram showing a configuration example of a conventionally used chemical decontamination apparatus.

[Explanation of symbols]

1, 1a, 1b: decontamination target, 2, 2a, 2b: decontamination tank, 3: reducing agent storage tank or storage tank, 4: oxidizing agent storage tank,
5 ... washing water storage tank, 6, 6a, 6b ... circulation pump, 7,
7a, 7b: Mixed-bed resin tower, 8, 8a, 8b: Cationic resin tower, 9, 9a, 9b: Heater, 10, 10a, 10b
... Reducing agent decomposition device, 11, 11a, 11b ... decomposition chemical injection device, 12 ... transfer pump, 13, 13a, 13b ... chemical inlet, 14 ... spray device, 40 ... pure equipment, 45
... drainage equipment, 54 ... decontamination liquid, 55 ... supply line, 56 ...
Overflow line, 57: supply valve, 58: circulation valve, 59: drain valve.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kazumi Anazawa 3-1-1 Sachimachi, Hitachi City, Ibaraki Prefecture Within the Nuclear Power Division, Hitachi, Ltd. (72) Inventor Ichiro Kataoka 3-chome, Sachimachi, Hitachi City, Ibaraki Prefecture No. 1 Inside Hitachi Engineering Co., Ltd.

Claims (16)

[Claims] 1. A chemical decontamination method in which an object to be decontaminated is placed in a decontamination tank to perform decontamination, wherein an oxidative decontamination agent is provided in a circulation path in which the decontamination tank, a heater and a circulation pump are connected by a circulation pipe. And oxidizing and decontaminating the object to be decontaminated using the oxidative decontamination liquid filled in the circulation path.After the oxidative decontamination, transferring the oxidative decontamination liquid to an oxidant storage tank, When performing oxidative decontamination, the oxidative decontamination liquid in the oxidant storage tank is transferred to the circulation path, and the object to be decontaminated is deoxidized using the oxidization decontamination liquid filled in the circulation path. A chemical decontamination method characterized by dyeing. 2. A chemical decontamination method in which an object to be decontaminated is placed in a decontamination tank to perform decontamination, wherein a reducing decontamination agent is provided in a circulation path in which the decontamination tank, a heater and a circulation pump are connected by a circulation pipe. Is charged, and the decontamination object is reduced and decontaminated using the reduced decontamination liquid filled in the circulation path.After the reduction decontamination, the reduced decontamination liquid is transferred to a reducing agent storage tank, When performing reduction decontamination, the reduction decontamination liquid in the reducing agent storage tank is transferred to the circulation path, and the decontamination object is reduced and decontaminated using the reduction decontamination liquid filled in the circulation path. A chemical decontamination method characterized by dyeing. 3. A chemical decontamination method in which an object to be decontaminated is placed in a decontamination tank to perform decontamination, wherein the decontamination tank, a circulation pump and a heater are connected to a first circulation path connected by a circulation pipe. The pure water is filled, the pure water is circulated by the circulation pump, the pure water is heated by the heater, and when the pure water reaches a predetermined temperature, the first circulation path is oxidized and decontaminated. An agent is charged, the oxidative decontamination solution filled in the first circulation path is held at a predetermined concentration for a predetermined time, and the object to be decontaminated is oxidized and decontaminated. Transferring the oxidative decontamination solution to an oxidant storage tank by a transfer pump, and supplying pure water to a second circulation path in which the decontamination tank, the circulation pump, the heater, and the cationic resin tower are connected by a circulation pipe. And circulating the pure water by the circulation pump,
The pure water is heated by the heater, and when the pure water reaches a predetermined temperature, a reducing and decontaminating agent is introduced into the second circulation path, and the reduction filled in the second circulation path is reduced. The decontamination solution is held at a predetermined concentration for a predetermined time to reduce and decontaminate the object to be decontaminated.After the reduction decontamination, the transfer pump transfers the reduced decontamination solution to a reducing agent storage tank. By transferring the decontamination tank, the circulation pump, the heater, and the mixed-bed resin tower with a third circulation path connected with a circulation pipe with pure water, and circulating the pure water with the circulation pump. A chemical decontamination method comprising washing the object to be decontaminated. 4. A chemical decontamination apparatus comprising a decontamination tank, a pump, a heater, a mixed-bed resin tower, a cationic resin tower, a reducing agent decomposer, and a decomposed chemical injector, wherein the decontamination tank is oxidized and decontaminated. An oxidizing agent storage tank for storing the oxidizing decontamination liquid used in the above, a reducing agent storing tank for storing the reducing decontamination liquid used for the reduction decontamination in the decontamination tank, the decontamination tank and the oxidizing agent storage tank Alternatively, a transfer pump for mutually transferring the decontamination liquid with the reducing agent storage tank is provided. 5. A chemical decontamination apparatus for decontaminating an object to be decontaminated in a decontamination tank, wherein the decontamination tank, a circulation pump and a heater for heating circulating water are connected by a circulation pipe. A first circulation path, a device for supplying an oxidative decontamination agent to the first circulation path when the circulating water is heated by the heater to reach a predetermined temperature, and A transfer pump for transferring the oxidative decontamination liquid in the dye tank and the circulation pipe to the oxidant storage tank; a second circulation path configured by adding a cationic resin tower on the first circulation path; A device for filling the mixture with the circulation pump, heating with the heater, and supplying a reducing agent to the second circulation path when the pure water reaches a predetermined temperature; and the decontamination tank after reduction decontamination. And transferring the reduced decontamination liquid in the circulation pipe by the transfer pump A decontamination and cleaning step, comprising: a reducing agent storage tank to be retained; and a third circulation path forming a circulation cleaning path by adding a mixed bed resin tower on the first circulation path. Chemical decontamination equipment. 6. The decontamination tank according to claim 5, further comprising a spray device for spraying the oxidative decontamination liquid, the reduction decontamination liquid or the cleaning water on the object to be decontaminated. And chemical decontamination equipment. 7. A chemical decontamination method in which an object to be decontaminated is placed in a decontamination tank and decontaminated, wherein the decontamination is performed using an oxidative decontamination liquid filled in a first circulation path including the decontamination tank. The object is oxidized and decontaminated, and after the oxidative decontamination, the oxidized decontamination liquid is transferred to an oxidizing agent storage tank, and the reduced decontamination liquid filled in a second circulation path including the decontamination tank is used. After reducing and decontaminating the object to be decontaminated, transferring the reduced decontamination solution to a reducing agent storage tank after the reduction decontamination, and performing the decontamination using water filled in a third circulation path including the decontamination tank. A chemical decontamination method characterized by washing an object to be dyed. 8. The method according to claim 7, wherein the first circulation path includes a circulation pump, the second circulation path includes a circulation pump and a cationic resin tower, and the third circulation path includes a circulation pump. A chemical decontamination method comprising a floor resin tower. 9. The chemical decontamination method according to claim 8, wherein the first circulation path includes a heater, and the second circulation path includes a heater and a reducing agent decomposing device. 10. The chemical decontamination method according to claim 9, wherein the heater is built in the decontamination tank. 11. The method according to claim 7, wherein after the cleaning, the cleaning liquid in the third circulation path is discharged; Transferring to the circulation path, transferring the oxidative decontamination and the oxidative decontamination liquid, transferring the reduced decontamination liquid in the reducing agent storage tank to the second circulation path, performing the reduction decontamination and A chemical decontamination method characterized by repeating a step of transferring a reduction decontamination solution and a step of performing the washing one or more times. 12. The method according to claim 7, wherein after the cleaning, the cleaning liquid is transferred to a cleaning water storage tank, and the oxidative decontamination liquid in the oxidant storage tank is transferred to the first circulation path. Transferring the oxidative decontamination solution and the oxidative decontamination solution, transferring the reduced decontamination solution in the reducing agent storage tank to the second circulation path, and performing the reduction decontamination and the reduction decontamination. A chemical decontamination method characterized by repeating a step of transferring a liquid and a step of transferring the cleaning liquid in the cleaning water storage tank to the third circulation path and performing the cleaning one or more times. 13. The oxidizing and decontaminating liquid in the oxidizing agent storage tank is transferred to the first circulation path after the transfer of the reducing and decontaminating liquid and before the cleaning. Transferring the oxidative decontamination solution and the oxidative decontamination solution, and transferring the reduced decontamination solution in the reducing agent storage tank to the second circulation path, and performing the reduction decontamination and the reduction decontamination. A chemical decontamination method characterized by repeating the step of transferring a liquid one or more times. 14. A chemical decontamination apparatus for performing decontamination by placing an object to be decontaminated in a decontamination tank, comprising: a first circulation path including the decontamination tank and a circulation pump; and oxidative decontamination by the circulation path. An oxidant storage tank for storing an oxidative decontamination solution in the first circulation path later; a second circulation path including the decontamination tank, the circulation pump, and the cationic resin tower; A reducing agent storage tank for storing the reduced decontamination solution in the second circulation path after the dyeing, and a third circulation path for washing including the decontamination tank, the circulation pump, and the mixed-bed resin tower. Chemical decontamination equipment characterized by performing. 15. The chemical decontamination apparatus according to claim 14, wherein the first circulation path includes a heater, and the second circulation path includes a heater and a reducing agent decomposing device. 16. A decontamination tank for performing oxidative decontamination and reduction decontamination of an object to be decontaminated, a circulation pipe for circulating a decontamination solution in the decontamination tank, an oxidative decontamination agent and reduction A chemical inlet for introducing a decontamination agent into the circulation pipe, an oxidant storage tank for storing an oxidative decontamination solution used for oxidative decontamination in the decontamination tank, and a reduction decontamination in the decontamination tank. A chemical decontamination apparatus comprising: a reducing agent storage tank for storing a used reduction decontamination liquid.