JP2557300B2 - Decontamination equipment that uses methylene chloride as a radioactive contaminant. - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention uses methylene chloride to remove radioactive contaminants such as nuclear reactor equipment used in nuclear power plants, peripheral equipment, piping, tools used, etc. It relates to a dyeing device.

[0002]

2. Description of the Related Art Conventionally, in a nuclear power plant or the like, radioactive pollutants are generated with the progress of its operation. It occurs when parts of various equipment such as the power plant are replaced or overhauled, and they are usually stored as they are or cut and stored in drums, and stored and stored in abandoned mines. However, in this case, the amount of storage increases year by year, and the storage space will soon become insufficient only with abandoned mines, etc., and storage facilities will usually be built in a region remote from the city with few residents to store the pollutants there. However, doing so often causes an opposition movement by the residents of the area where the storage facility is installed, causing social problems. A number of inventions have been made to solve such problems, all of which attempt to decontaminate radioactive contaminants to reduce the amount of the contaminants stored.

As an example of such prior art, Japanese Patent Publication No.
The invention described in 9-36240 is mentioned. This invention contains fluorohydrocarbon, perchlorethylene or the like in a container, heats them, and vibrates them using an ultrasonic vibration device, and puts radioactively contaminated objects in these solutions. , Is to be decontaminated.

[0004]

However, the above-mentioned conventional methods have the following drawbacks. First, both of the fluorohydrocarbon and perchlorethylene have low radioactive decontamination ability. This low decontamination ability is extremely low, as will be apparent from the results of experiments for comparison with the present invention described later. Second, the fluorohydrocarbon and perchlorethylene both cause pollution. As is well known about the pollution caused by fluorohydrocarbons, it destroys the ozone layer surrounding the earth and forms ozone holes, so that the absorption of solar ultraviolet rays by ozone is extinguished, thereby increasing the number of cancer patients worldwide. Has been banned from use by the United Nations, and the manufacture and use of the products are prohibited by the end of this century under the Montreal Protocol by the member states of the United Nations. Also, perchlorethylene has a carcinogenic property, and when it is released into the air, it causes poisoning by contact with skin and ingestion from the mouth and causes pollution. Permissible concentration of perchlorethylene in air is 100ppm
Is. Perchlorethylene is 19 in the United States.
Manufacture and use will be banned in 1996.

Next, in the process of decontaminating radioactive pollutants, the above-mentioned perchlorethylene decontaminates perchlorethylene itself which is a decontaminating agent, that is, decontamination of perchlorethylene itself by distillation. At the time of this decontamination, the high boiling point (boiling point 121.2 ° C) consumes a large amount of power and inefficiency is inevitable. In addition, the above-mentioned perchlorethylene is added with an appropriate organic substance as a stabilizer, but as described above, the amount of the stabilizer becomes small at the time of decontamination of perchlorethylene itself, and if it is used as it is, it damages the metal. It has some drawbacks. Further, the above-mentioned perchlorethylene is generally inferior in stability to electromagnetic waves. Perchlorethylene is oxidized by ultraviolet rays and converted to trichloroacetyl chloride. Moreover, even if it is exposed to sunlight for a long time, it is hydrolyzed and converted into trichloroacetic acid and hydrochloric acid.
Therefore, there is a risk of being changed by α rays, β rays, γ rays, etc. emitted from radioactive contaminants. The present invention has been made to solve various problems as described above,
The purpose is that the decontamination ability of radioactive is much higher than the decontamination method of the above-mentioned prior art, does not bring about significant pollution, and also in the case of decontamination of the decontamination agent itself during the decontamination process, the power consumption is It requires much less than the prior art, therefore it is efficient, there is no obstacle to decontamination of the decontamination agent itself, and it is relatively stable to decontaminate against the radiation generated from radioactive contaminants. The purpose is to provide a decontamination device using methylene chloride as a radioactive contaminant.

[0006]

The present invention which achieves the above object is described as follows. A decontamination chamber 1 for cleaning and decontaminating radioactive contaminants using methylene chloride; in communication with the decontamination chamber 1. A filter 13 provided in the next stage of the decontamination chamber 1 using a packing 34 made of perfluoroelastomer for separating methylene chloride from the deposits separated from the radioactive contaminants; the filter 1
3 and a passage 37 formed between the decontamination chamber 1 for supplying methylene chloride filtered by the filter 13 to the decontamination chamber 1 using a packing 34 made of perfluoroelastomer. Is a decontamination device using methylene chloride as a radioactive contaminant.

In the passage 37, there is a distillation device 18 located between the filter 13 and the decontamination chamber 1 for distilling methylene chloride filtered by the filter 13 and a packing 34 made of perfluoroelastomer. It is a decontamination device using methylene chloride of radioactive contaminants that are communicated with each other. Further, the distillation apparatus 18 uses a packing 34 formed of perfluoroelastomer, and removes the radioactive contaminant methylene chloride which is communicated with the nozzle 2 provided in the decontamination chamber 1 through the high pressure pump 9. It is a dyeing device. Further, the decontamination chamber 1 has a decontamination device 29 provided corresponding to the decontamination chamber 1 for decontaminating radioactive contaminants decontaminated in the decontamination chamber 1 with a chelate solution 30. It is a decontamination device that uses methylene chloride as a contaminant. Further, the decontamination chamber 1 has a container 16 provided corresponding to the decontamination chamber 1 for containing a radioactive contaminant and a methylene chloride solution for immersing and impregnating the radioactive contaminant in the methylene chloride solution. It is a decontamination device that uses methylene chloride as a radioactive contaminant.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, reference numeral 1 is a decontamination chamber, in which a nozzle 2 is provided in a closed chamber, and the nozzle 2 is provided toward a radioactive contaminant 3. Radioactive pollutant 3
Generally speaking, many devices in a nuclear power plant are generally coated with a paint using an epoxy resin, and the contaminant 3 shown in the figure has a layer of the epoxy resin paint deposited on the metal 4 as the deposit 5. It shows the case. Reference numeral 6 denotes a support member for the contaminant 3 provided in the decontamination chamber 1. Further, 7 is a methylene chloride solution jetted from the nozzle 2, 8 is a communication passage, 9 is a high pressure pump, and 10 is an opening / closing device. Further, 11 is a passage leading to the adsorption device 12 using activated carbon, and 13 is a filter, which is the decontamination chamber 1
The tank 1 is connected to the bottom and has an outlet 14 for deposits.
It is connected to 5.

The decontamination chamber 1 may be formed as shown in FIG. In the apparatus shown in FIG. 3, the nozzle is provided in the methylene chloride solution 7, and the impact of the methylene chloride solution 7 on the contaminant 3 is performed in the methylene chloride solution 7. FIG. 1
In the case of the decontamination chamber 1 shown in (1), the impact with the methylene chloride solution 7 is performed in the air. Next, according to the present invention, the contaminant 3 may be immediately bombarded with a methylene chloride solution as described above, but it is normally carried out as follows. That is, FIG.
As shown in, the radioactive contaminant 3 is previously dipped in the methylene chloride solution 7 in the container 16.

Then, the deposit 5 is impregnated and swells in the case of a paint using an epoxy resin. In this state in which the deposit 5 is swollen and easily peeled off, the contaminant 3 is supported by the support member 6, and the methylene chloride solution 7 is impacted by the nozzle 2. Next, 13 is a filter as described above, which filters the methylene chloride solution 7 containing the deposit 5 and separates the deposit 5 from the discharge port 14 into the tank 15 and discharges it. ing. Reference numeral 17 indicates a pump. Next, 18 is a distillation apparatus for distilling the methylene chloride solution 7 filtered by the filter 13. The methylene chloride solution 7 is distilled in this distillation apparatus 18 to decontaminate the methylene chloride solution 7 itself. 19 is a distillation chamber, 20 is a heater, 21 is a cooling device,
22 is a fin, 23 is a drip collecting plate, and 24 is a second tank. A cooler 25 cools the adsorber 12 when adsorbing the gas.

Although the adsorption device 12 is heated at the time of desorption, the heater used therefor is not shown. At that time, the carrier air heated by a device (not shown) is supplied and desorbed, and the carrier air is liquefied by cooling to a temperature below the boiling point of the gas in the liquefying device 26,
Be recovered. As such an apparatus, as an example, the adsorption apparatus of the invention (Patent application No. 76089 of 1991) previously filed and disclosed by the applicant of the present invention was used. At the time of the liquefaction, a part of the gas that has escaped the liquefaction is cooled to a temperature below the freezing point of the gas by a device (not shown) to be solidified, and the solidified gas is heated and liquefied and recovered. Thus, the gas is completely recovered. Then, as described above, the methylene chloride solution recovered by using an apparatus not shown is also decontaminated by the distillation apparatus 18,
A high pressure pump 9 is used to feed the second tank 24 to the nozzle 2 of the decontamination chamber 1. Reference numeral 27 is a blower, and 28 is a discharge passage for clean air.

Next, an apparatus 29 shown in FIG. 4 is a decontamination apparatus using a chelate solution 30, and the contaminant 3 decontaminated in the decontamination chamber 1 is further removed by using this decontamination apparatus 29. To dye. Reference numeral 31 denotes an inlet of the chelate solution, and 32 denotes an outlet thereof, so that the chelate solution 30 can be constantly circulated. Reference numeral 33 denotes an ultrasonic vibrating device, by which the chelate solution 30 can be vibrated. The method of this embodiment using the above apparatus will be described. First, the radioactively contaminated object 3 is immersed in a methylene chloride solution 7 as shown in FIG. This object 3 is measured by a Geiger counter as an example.
It was PM (Count Per Minute). This contaminant 3
As described above, the paint layer using the epoxy resin is the attached matter 5
As a result, the deposit 5 was substantially impregnated and swollen in the shape of a jellyfish due to the immersion. The immersion time is, for example, about 20 minutes. Next, the contaminant 3 was taken out and washed by impacting with a jet injection of the methylene chloride solution 7 in the decontamination chamber 1 as shown in FIG. This impact may be, for example, about 5 minutes, and the coating layer swollen by this impact was peeled off. It should be noted that such an operation has substantially the same effect even if it is carried out in the methylene chloride solution 7 as shown in FIG. The radioactivity of the contaminant 3 after the washing was 50 CPM. The radioactive contaminants may be previously sandblasted or shot blasted before being washed with methylene chloride.

Next, the object is the chelate solution 3 shown in FIG.
Ultrasonic cleaning was performed with 0. The chelate solution 30
Was washed by adding a surfactant and circulating it to a tank (not shown). After this cleaning, rinse with fresh water was performed. After this cleaning, the contamination 3 was measured and found to be 0 CPM. On the other hand, in the methylene chloride solution 7 discharged from the decontamination chamber 1, the deposits 5 are separated by filtration in the filter 13, and after passing through the tank 15, the distillation apparatus 1
8, and the methylene chloride solution 7 itself is decontaminated by this, and the methylene chloride solution 7 itself is decontaminated to 0 CPM, which is supplied to the nozzle 2 through the second tank 24 and the high-pressure pump 9, and the following operations are repeated.

Next, using the fluorohydrocarbons and perchlorethylene and other chlorine-based solvents shown in the above-mentioned conventional example, and the methylene chloride solution 7 of the present invention, impregnation, swelling and swelling of the deposit 5 as described above are carried out. When the decontamination effects of decontamination in the decontamination room 1 were compared, the results are shown in Table 1 below.

[Table 1]

As shown in Table 1 above, methylene chloride has a far superior decontamination effect against the above-mentioned conventional fluorohydrocarbons, perchlorethylene, and other chlorine-based solvents. It is clear. The toxicity of methylene chloride is the lowest in chlorine-based solvents, and the permissible concentration in air is 500 ppm, which is five times that of perchlorethylene. Further, methylene chloride has a boiling point of 40 ° C. and 4 ° C., which is extremely low. Therefore, power consumption during decontamination of the solvent itself by distillation can be extremely low. Further, methylene chloride has the most stable molecular structure in a chlorine-based solvent, and therefore, there is no fear of alteration of perchlorethylene due to heating and cooling during distillation.
Further, since there is no fear of alteration such as alteration with respect to ultraviolet rays and sunlight rays unlike the above-mentioned perchlorethylene, it can be expected that there is no fear of alteration with respect to radiation emitted by contaminants.

Next, in general, it has been practically difficult to use a methylene chloride solution as a decontamination device. The reason is that there was no packing that was insoluble in the methylene chloride solution and had little loss of elasticity upon irradiation with radiation. Therefore, the inventor of the present invention found a special packing satisfying the above condition and solved it by using it. It is a packing formed of perfluoroelastomer, and is an elastomer manufactured and sold by DuPont in the United States and having a trade name of Kalrez. By using the packing made of this perfluoroelastomer and also for the valve of a pump, methylene chloride can be used, whereby an excellent decontamination device can be obtained. In FIG. 1, reference numeral 34 denotes packing made of the above-mentioned perfluoroelastomer, and as shown in the drawing, between the decontamination chamber 1 and the pipe 35, the filter 13 and the pipe 3.
5, between the tank 15 and the pipe 35, the distillation device 18
And the pipe 35, between the second tank 24 and the pipe 35,
And provided between the pump 9 and the pipe 35, and the like. Although not shown, the pump 9 is also provided with a valve and the like. By forming in this way, various devices can be connected to the pipe 35.
The inside of these pipes 35 can be easily decontaminated. The perfluoroelastomer is practically insoluble in methylene chloride and has no change in elasticity. Furthermore, as shown in FIG. 5, the retention of stretchability against radiation is excellent. Figure 5
The ones shown in Figure 2 show the results of experiments conducted with gamma rays, which are far superior to those of Viton.

[0017]

The present invention is constructed as described above and uses the packing 34 made of perfluoroelastomer in the passage 37 between the decontamination chamber 1 and the filter 13 and between the filter 13 and the decontamination chamber 1. By virtue of this, and by adopting the constitution as claimed in claims 2 to 5, it is possible to actually use methylene chloride which does not dissolve in methylene chloride for the first time and has little elastic loss by radiation. Radioactivity decontamination can be performed by. Therefore, it is possible to exert far superior decontamination ability as compared with the conventional solvent. Further, it does not cause significant pollution such as the use of fluorohydrocarbon and perchlorethylene. Further, decontamination of the decontamination agent itself can be performed with much lower power consumption than the conventional solvent. And, at that time, the molecular structure is much more stable than conventional solvents such as perchlorethylene. Further, since there is little risk of deterioration due to ultraviolet rays such as perchlorethylene, it can be expected that there is little risk of deterioration due to radiation. And the above-mentioned effects can be actually exhibited for the first time. Further, since the packing 34 made of perfluoroelastomer has high durability against radiation as described above, the maintenance of the device can be facilitated.

[Brief description of drawings]

FIG. 1 is a view showing an example of the present invention, and is a view showing an outline of an apparatus used in a method for decontaminating radioactive contaminants with methylene chloride.

FIG. 2 is a diagram showing a step before the step shown in FIG.

FIG. 3 is a diagram showing another embodiment of a part of the apparatus shown in FIG.

FIG. 4 is a diagram showing a step that follows the step performed by the apparatus shown in FIG.

FIG. 5 shows a perfluoroelastomer used in the present invention,
It is a graph which shows the retention rate of the elongation with respect to a radiation.

[Explanation of symbols]

 1 Decontamination chamber 2 Nozzle 3 Radioactive contaminant 7 Methylene chloride solution 13 Filter 18 Distiller 30 Chelate solution

Claims (5)

(57) [Claims] 1. A radioactive contaminant is washed and decontaminated with methylene chloride ; a decontamination chamber 1;
In the next stage of the decontamination chamber 1, a perfluoroelastomer is used.
Provided using a packing 34 formed by
Deposits and methylene chloride stripped from radioactive contaminants
Filter 13 for separating the screen; the filter 13 and the decontamination
Meth formed between the chambers 1 and filtered by the filter 13.
Supplying len chloride to the decontamination chamber 1
Using packing 34 made of elastomer
A decontamination device using methylene chloride for radioactive contaminants , characterized in that it comprises a passage 37; 2. The path 37 and the filter 13 are decontaminated.
Located between the chamber 1 and the filter filtered by the filter 13
The distillation device 18 for distilling chloride is
The packing 34 formed by the elastomer is used to connect
A radioactive contaminants methyle according to claim 1 which is passed through.
Decontamination equipment using chloride. 3. The distillation device 18 is a perfluoroelastomer.
Using the packing 34 formed by the high pressure pump 9
Through the nozzle 2 provided in the decontamination chamber 1
3. The radioactive contaminant methylene chloride of claim 2.
Decontamination device that uses a cord. 4. A decontamination chamber 1 is provided corresponding to the decontamination chamber 1.
The radioactive contaminants decontaminated in the decontamination room 1 are further filtered.
Contractor having decontamination device 29 for decontamination with rate solution 30
Methylenechlora as a radioactive contaminant according to claim 1, 2 or 3.
Decontamination device using id. 5. The decontamination chamber 1 is provided corresponding to the decontamination chamber 1.
Soaked radioactive contaminants in methylene chloride solution
Impregnated with radioactive contaminants and methylene chloride
A container 16 for containing a liquid is provided, and the container 16 is provided with the container 16.
Decontamination of the listed radioactive contaminants with methylene chloride
apparatus.