JP2013210209A - Removal device for radioactive material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radioactive material removal device for removing a radioactive material as a contamination source from water contaminated with the radioactive material, which is configured to perform treatment with a higher current speed than a column system absorption tower, and can avoid such a risk that the radioactive material leaks.SOLUTION: The device for removing a radioactive material from water contaminated with the radioactive material is configured such that a container with a double cylindrical structure constituted of an inner cylinder and an outer cylinder for packing absorbent is stored in an outer container, and that the water contaminated with the radioactive material passes from the inner cylinder packed with the absorbent via the outer cylinder, and circulates via the outer container to the inner cylinder. Thus, it is possible to remove the radioactive material.

Description

  The present invention relates to an apparatus for adsorbing and removing a radioactive substance from water containing a radioactive substance, and more specifically, water containing a radioactive substance can be treated at a higher flow rate than a column type adsorption tower, and the radioactive substance It is related with the radioactive substance removal apparatus which can prevent the leakage of the water containing.

  Radioactive material scattering caused by the Great East Japan Earthquake has spread to a wide range of surrounding areas, not just within the power plant, and continues to detect radiation exceeding the standard value. In these areas, radioactive materials are seriously decontaminated. It is a problem.

  Water that is used for cooling in the power plant during the earthquake and contaminated with high-concentration radioactive materials cannot be returned to the environment without removing the radioactive materials. In addition, water used for cleaning roads, facilities, soil, etc. contaminated with scattered radioactive substances is also required to remove the radioactive substances if the concentration contains radioactive substances exceeding the standard.

  Attempts have been made to treat water contaminated with radioactive substances using column-type adsorption towers packed with adsorbents, but in the case of column-type adsorption towers, clogging increases the differential pressure and increases the treatment speed. There is a problem that there is no concern about leakage of radioactive materials due to damage of the device when there is no difference or when the differential pressure becomes large.

  The present invention is a device that removes radioactive substances that are the source of contamination from water contaminated with radioactive substances, which can be processed at a higher flow rate than a column type adsorption tower and avoids the risk of leakage of radioactive substances. It is an object of the present invention to provide a radioactive substance removing device that can be used.

  The present inventors have intensively studied, and a double-cylinder container composed of an inner cylinder and an outer cylinder is accommodated in the outer container, and the inner cylinder and the outer cylinder are filled with an adsorbent and contaminated with radioactive substances. The inventors have found that the above problem can be solved by an apparatus having a structure in which water passes from the inner cylinder to the outer cylinder, passes through the outer container, and circulates to the inner cylinder.

That is, the present invention
An apparatus for removing radioactive material from water contaminated with radioactive material,
A container with a double cylinder structure consisting of an inner cylinder and an outer cylinder for filling the adsorbent is housed in the outer container,
The inner cylinder is placed on a pedestal provided at the bottom of the outer cylinder, the top surface is sealed by a lid provided with a water injection pipe, and the inner cylinder drainage port comprising a plurality of holes is provided on the bottom surface And
The outer cylinder is placed on a pedestal provided at the bottom of the outer container, and the top surface has a diameter that allows the water injection pipe to pass therethrough and a lid provided with a pipe that can seal a gap between the water injection pipe and the outer cylinder. It has a structure in which outer cylinder drains are provided at multiple locations on the upper side.
The outer container has a structure in which the top surface is covered with a lid having a pipe having a diameter through which the water injection pipe can be passed, and an outer container drain is installed on the side surface near the bottom surface.
The outer container drain is connected to the water injection pipe via a circulation pump,
An apparatus for removing a radioactive substance is provided.

  The radioactive substance removing apparatus of the present invention has a large inner diameter of the inner cylinder and the outer cylinder, and can provide a plurality of water outlets by providing a plurality of outlets from the outer cylinder. It is possible to prevent clogging, that is, increase in differential pressure. Therefore, it is possible to increase the flow rate of water contaminated with radioactive substances. Furthermore, since it is designed to be stored in the outer container, the contaminated water overflowing from the outer cylinder can be discharged from the bottom of the outer container even when clogging occurs. It is possible to prevent the occurrence of a situation in which the contained pressure water leaks.

It is a schematic sectional drawing which shows the principal part of the removal apparatus of the radioactive substance of this invention. It is the schematic which shows the whole removal apparatus of the radioactive substance of this invention.

  The radioactive substance removing apparatus of the present invention will be described in more detail with reference to FIGS.

  As shown in FIG. 1, a gantry 12 a is installed on the bottom surface of the outer cylinder 2, and the inner cylinder 1 is placed so as to be fitted into the gantry 12 a. And the base 12b is installed also in the bottom face of the outer container 3, and the outer cylinder 2 is mounted in the form fitted in the base 12b.

  The inner cylinder 1 is sealed with a lid 10 a, and the water injection pipe 4 is joined so as to penetrate the lid 10 a, and the tip of the water injection pipe 4 is introduced into the upper space of the inner cylinder 1. The plurality of holes constituting the inner cylinder drain port 5 are formed by installing a porous plate, mesh, or filter at the bottom of the inner cylinder 1, and the adsorbent fills the porous plate, mesh, or filter.

  Although the outer cylinder 2 is also sealed by the lid 10b, a pipe 11a is installed on the lid 10b of the outer cylinder 2, and the water injection pipe 4 passes through the outer cylinder 2 by passing through the pipe 11a. It has a structure. And the outer cylinder 2 will be sealed by the lid | cover 10b by closing the space | gap part produced between the pipe | tube 11a and the piping 4 for water injection with a packing, a washer, etc. Outer cylinder drain ports 6 are provided at a plurality of locations on the upper side of the outer cylinder 2, and the adsorbent is filled so as not to exceed the outer cylinder drain port 6.

  Further, the water injection pipe 4 also penetrates the lid 10c of the outer container 3, and the pipe having a diameter that allows the water injection pipe 4 to pass through the lid 10c of the outer container 3 as in the case of the lid 10b of the outer cylinder 2. 11b is provided, but in the case of the lid 10c of the outer container 3, the gap formed between the pipe 11b and the water injection pipe 4 is not closed and serves as a pressure relief. An outer container drain port 7 is provided on the side wall near the bottom of the outer container 3 so that the effluent from the outer cylinder drain port 6 can be discharged.

  Examples of the adsorbent filled in the inner cylinder and the outer cylinder include zeolite and activated carbon, and the adsorbent filled in the inner cylinder and the adsorbent filled in the outer cylinder may be the same or different. Good.

  Next, a method for treating water contaminated with a radioactive substance by the radioactive substance removing apparatus of the present invention will be described with reference to FIG. The arrows in FIG. 2 schematically represent the flow of contaminated water in the inner cylinder 1, the outer cylinder 2 and the outer container 3.

  In the radioactive substance removal apparatus of the present invention, the water contaminated with the radioactive substance (hereinafter referred to as contaminated water) can be circulated in the apparatus and treated with the adsorbent a plurality of times. It is also possible to perform a one-pass process in which contaminated water is treated only once with an adsorbent.

  The circulation process can be performed as follows. That is, the water injection pipe 4 and the contaminated water introduction pump 21 are connected by the switching valve 22 a, and the contaminated water stored in the contaminated water storage tank 30 is introduced into the inner cylinder 1 using the contaminated water introduction pump 21. The contaminated water introduced into the inner cylinder 1 flows down through the adsorbent 13 a filled in the inner cylinder 1 and then flows out from the inner cylinder drain port 5 to the outer cylinder 2. The contaminated water flowing out to the outer cylinder 2 rises in the adsorbent 13 b filled in the outer cylinder 2 and then overflows to the outer container 3 from the outer cylinder drain port 6. Then, after the contaminated water that has passed through the adsorbent is accumulated in the outer container 3 until a predetermined amount is reached, the contaminated water introduction pump 21 is stopped, the switching valve 22a is switched, and the water injection pipe 4 is connected to the circulation pump 20. Then, the circulating pump 20 is operated, and the contaminated water accumulated in the outer container is extracted from the outer container drain 7 and introduced into the inner cylinder 1 through the water injection pipe 4 and circulated.

  Although not shown, contaminated water can also be introduced into the outer container 3 by providing a separate water injection pipe in the outer container 3 and connecting it to the contaminated water introduction pump 21. In this case, the contaminated water is directly introduced into the outer container 3 and a predetermined amount of contaminated water is stored in the outer container 3, and then the circulation pump 20 is operated to draw out from the outer container drain port 7, and the water injection pipe 4 is connected. Then, contaminated water is introduced into the inner cylinder 1 and circulated.

  After the circulation process, the switching valve 22b is switched to connect the circulation pump 20 to the treated water storage tank 31, so that the treated water can be sent out to the treated water storage tank 31 by the circulation pump 20.

  The one-pass process can be performed as follows. The water injection pipe 4 and the contaminated water introduction pump 21 are connected by the switching valve 22a, and the contaminated water stored in the contaminated water storage tank 30 is introduced into the inner cylinder 1 via the water injection pipe 4 by the contaminated water introduction pump 21. To do. The contaminated water introduced into the inner cylinder 1 flows down through the adsorbent 13a filled in the inner cylinder 1 and is adsorbed, and then flows out from the inner cylinder drain port 5 to the outer cylinder 2 and fills the outer cylinder 2. The adsorbent 13b rises and is further adsorbed, and overflows from the outer cylinder drain port 6 to the outer container 3. Then, the circulation pump 20 is connected to the treated water storage tank 31 by the switching valve 22 b, and the treated water overflowing the outer container 3 is extracted from the outer container drain 7 by the circulation pump 20, and is supplied to the treated water storage tank 31. Processing can be performed in one pass by sending.

(Test Example 1)
1 and FIG. 2, the inner cylinder 1 has an inner diameter of 22 cm and a height of 40 cm, the outer cylinder 2 has an inner diameter of 30 cm and a height of 45 cm, the outer container 3 has an inner diameter of 50 cm and a height of 60 cm. The inner cylinder 1 was filled with 700 g of coconut shell activated carbon (KD-GA-X manufactured by UES Co., Ltd.) having a size of 2 to 5 mm × 3 to 7 mm and a thickness of 1 to 1.5 mm. Then, 500 g of zeolite having a particle diameter of 2 to 5 mm was filled in the outer cylinder 2, and then a filter material was disposed on the zeolite layer in order to prevent the zeolite from flowing out.
Also, an aqueous solution containing cesium chloride (about 1.8 ppm as cesium), iodine (about 6 ppm) and strontium chloride (about 19 ppm as strontium) was prepared to give simulated contaminated water with radioactive substances.
After introducing the simulated contaminated water 20L into the outer container 3, the circulation pump 20 is operated to introduce the simulated contaminated water into the inner cylinder 1 at a pressure of 0.1 MPa and circulate the simulated contaminated water in the apparatus. The test was conducted. The flow rate of the simulated contaminated water was approximately 1 L / min, and this flow rate could be kept almost constant during the test, and there was no change in pressure during that time.
The treatment liquid in the outer container 3 was sampled as appropriate, and the concentrations of cesium, iodine and strontium were measured, and the removal rate was calculated from the measured concentration values. Table 1 shows the concentrations and removal rates of cesium, iodine and strontium over time.

(Comparative Test Example 1)
The adsorption test was carried out using a column adsorption tower consisting of three columns having an inner diameter of 5 cm and a height of 50 cm. The first and second columns were filled with 350 g of the same coconut husk activated carbon as in Test Example 1, and the third column was charged with 500 g of the same zeolite as in Test Example 1, and these columns were sequentially connected in series. In addition, in the same manner as in Test Example 1, an aqueous solution containing cesium chloride (cesium as 1.88 ppm), iodine (5.72 ppm) and strontium chloride (21.1 ppm as strontium) was prepared to simulate water contaminated with radioactive substances. It was.
The introduction of simulated contaminated water was started using a pump. When the water flow rate was 0.2 L / min, the differential pressure became 0.9 MPa, and when trying to increase the water flow rate, liquid leakage occurred in the pipe connection part. It couldn't be speed.

DESCRIPTION OF SYMBOLS 1 Inner cylinder 2 Outer cylinder 3 Outer container 4 Piping for water injection 5 Inner cylinder drain port 6 Outer cylinder drain port 7 Outer container drain port 10a, 10b, 10c Lid 11a, 11b Pipe 12a, 12b Mount 13a, 13b Adsorbent 20 Circulation pump 21 Contaminated water introduction pump 22a, 22b Switching valve 30 Contaminated water storage tank 31 Treated water storage tank

Claims (1)

An apparatus for removing radioactive material from water contaminated with radioactive material,
A double cylinder container consisting of an inner cylinder and an outer cylinder for filling the adsorbent is housed in the outer container,
The inner cylinder is placed on a pedestal provided at the bottom of the outer cylinder, the top surface is sealed by a lid provided with a water injection pipe, and the inner cylinder drainage port comprising a plurality of holes is provided on the bottom surface And
The outer cylinder is placed on a pedestal provided at the bottom of the outer container, and the top surface has a diameter that allows the water injection pipe to pass therethrough and a lid provided with a pipe that can seal a gap between the water injection pipe and the outer cylinder. It has a structure in which outer cylinder drains are provided at multiple locations on the upper side.
The outer container has a structure in which the top surface is covered with a lid having a pipe having a diameter through which the water injection pipe can be passed, and an outer container drain is installed on the side surface near the bottom surface.
The outer container drain is connected to the water injection pipe via a circulation pump,
The radioactive substance removal apparatus characterized by the above-mentioned.

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