Storage methods for radioactive liquids
A dual-tank system for radioactive liquid storage addresses the challenge of high radiation doses by using a second tank to absorb radiation from a first tank, enhancing storage capacity and preventing leakage.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- KURITA WATER INDUSTRIES LTD
- Filing Date
- 2024-12-27
- Publication Date
- 2026-07-09
AI Technical Summary
Existing single-layered tanks for storing radioactive liquids require shielding materials to manage high radiation doses, which increases costs and reduces storage capacity.
A dual-tank system comprising a first tank for high-radiation liquid and a second tank for low-radiation liquid, where the second tank surrounds the first tank, absorbing radiation from the first tank and preventing leakage.
The method enhances storage capacity by allowing high-radiation liquid in the first tank while minimizing external radiation exposure through the second tank's absorption of radiation from the first tank, preventing leakage.
Smart Images
Figure 2026115911000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a method for storing radioactive liquid, and particularly to a method for storing radioactive liquid in a tank.
Background Art
[0002] When an accident occurs at a nuclear power plant, contaminated water containing radioactive substances is generated. The generated contaminated water is temporarily stored in a storage tank, and radioactive substances are sequentially removed from the contaminated water using a treatment device.
[0003] Tanks for storing radioactive liquid are usually single-layered (Patent Documents 1 to 3).
Prior Art Documents
Patent Documents
[0004]
Patent Document 1
Patent Document 2
Patent Document 3
Summary of the Invention
Problems to be Solved by the Invention
[0005] When the radiation dose of the radioactive liquid stored in the tank is high, it is necessary to surround the tank with a shielding material. However, not only does the material cost of the shielding increase, but the radioactive liquid storage space is reduced by the volume of the shielding material.
[0006] An object of the present invention is to provide a method for storing radioactive liquid that can store radioactive liquid with a high radiation dose and can increase the amount of radioactive liquid stored in the entire radioactive liquid storage space.
Means for Solving the Problems
[0007] A method for storing radioactive liquid according to one aspect of the present invention involves using a storage tank having a first tank and a second tank surrounding the first tank, and storing the radioactive liquid in the first tank and the second tank, wherein the radioactive liquid stored in the second tank has a lower radiation dose than the radioactive liquid stored in the first tank.
[0008] In one embodiment of the present invention, a method for storing radioactive liquids, the radiation dose of the radioactive liquid in the first tank is 1,000 to 20,000 times greater than the radiation dose of the radioactive liquid in the second tank.
[0009] In one embodiment of the present invention, a method for storing a radioactive liquid is radioactive wastewater.
[0010] In one embodiment of the present invention, a method for storing radioactive liquid, the second tank has a cylindrical portion that constitutes the side circumferential surface of the tank, and a bottom plate and a top plate that constitute the bottom and top surfaces of the tank, the first tank is cylindrical and is coaxially arranged inside the second tank, and the bottom surface of the first tank and the bottom surface of the second tank are made of a common bottom plate.
[0011] In a method for storing radioactive liquid according to one aspect of the present invention, the radiation dose of the radioactive liquid contained in the first tank is 6.67 × 10¹⁴ Cs-134. 5 Bq, Cs-137: 2.0 × 10 7 The volume is Bq, the diameter of the first tank is 600 to 1000 mm, and the distance between the outer surface of the first tank and the inner surface of the second tank is 500 to 1000 mm. [Effects of the Invention]
[0012] In the radioactive liquid storage method of the present invention, a radioactive liquid with a high radiation dose is stored in a first tank, and a radioactive liquid with a lower radiation dose is stored in a second tank surrounding the first tank. The radiation generated from the radioactive liquid in the first tank is shielded by the low-radiation liquid in the second tank, thus preventing (suppressing) leakage to the outside.
[0013] Moreover, even if radioactive liquid with a high radiation dose flows out from the first tank to the second tank by any chance, it will not flow out to the outside.
Brief Description of the Drawings
[0014] [Figure 1] It is a longitudinal sectional view of a storage tank used in the method for storing radioactive liquid according to the embodiment.
Embodiments for Carrying Out the Invention
[0015] Hereinafter, embodiments will be described with reference to the drawings.
[0016] In the present invention, as shown in FIG. 1, radioactive liquid is stored using a storage tank 10 having a first tank 1 and a second tank 2 surrounding the first tank 1. In FIG. 1, the second tank 2 has a cylindrical portion 2a with the cylindrical axis direction as the vertical direction, a bottom plate 2b closing the bottom of the cylindrical portion 2a, and a top plate 2c closing the zenith of the cylindrical portion 2a. In this embodiment, the bottom plate 2b has a shape that curves convexly downward, but it may be flat.
[0017] The first tank 1 has a cylindrical shape coaxial with the cylindrical portion 2a. The lower end of the first tank 1 is watertightly connected to the bottom plate 2b by welding or the like. Therefore, the bottom of the first tank 1 is constituted by the bottom plate 2b.
[0018] The upper end of the first tank 1 is located slightly below the top plate 2c.
[0019] The top plate 2c is provided with a liquid supply port 3 into the first tank 1, a liquid supply port 5 into the second tank 2, and a manhole 7.
[0020] The bottom plate 2b is connected with a drain pipe 4 from the first tank 1 and a drain pipe 6 from the second tank 2. Valves 4v and 6v are provided in the pipes 4 and 6 respectively.
[0021] The upper part of the first tank 1 is horizontally supported by a cross - bridge - formed stay 8 between the upper parts of the second tank 2.
[0022] Although illustration is omitted, the first tank 1 and the second tank 2 are provided with instrumentation devices such as a water - level sensor and a temperature sensor. Further, a vent port is provided at the upper part of the storage tank 10 so that the gas in the tank can be sent to a radioactive substance absorption part (not shown).
[0023] As the constituent materials of the first tank 1 and the second tank 2, metals such as stainless steel, synthetic resins, reinforced concrete, etc. can be used.
[0024] When the radioactive liquid stored in the first tank 1 is radioactive drainage with a radiation dose of about 6.67×10 5 Bq for Cs - 134 and 2.0×10 7 Bq for Cs - 137, the ratio D1 / D2 of the diameter (inner diameter) D1 of the first tank 1 to the diameter (inner diameter) D2 of the second tank 2 is 0.3 - 0.5, and particularly preferably about 0.4.
[0025] Also, in this case, the distance between the outer peripheral surface of the first tank 1 and the inner peripheral surface of the second tank 2 is preferably 500 mm or more, particularly 600 mm or more.
[0026] In the method for storing radioactive liquid of the present invention, a high - radiation - dose radioactive liquid is introduced into and stored in the first tank 1 of the storage tank 10 configured as described above. Also, a radioactive liquid with a lower radiation dose than that is introduced into and stored in the second tank 2. Examples of the radioactive liquid include radioactive drainage, but it may also be service water.
[0027] Since the radiation from the radioactive liquid in the first tank 1 is absorbed by the water in the second tank 2, the radiation dose passing through the cylindrical part 2a of the second tank is small. Also, even if a high - radiation - dose radioactive liquid accidentally flows out from the first tank 1 to the second tank 2, it will not flow out to the outside.
[0028] In the above embodiment, the bottom plate of the first tank 1 and the bottom plate of the second tank 2 are common, but the bottom plates of the first tank 1 and the second tank 2 may be separate, and the bottom plate of the first tank 1 may be positioned higher than the bottom plate of the second tank 2. That is, the low-dose radioactive liquid in the second tank may be located between the bottom plate of the first tank 1 and the bottom plate of the second tank 2.
[0029] Alternatively, a shielding material may be placed on the upper side of the top panel 2c.
[0030] The radiation dose of the high-radiation liquid contained in the first tank 1 is approximately 1,000 to 20,000 times that of the liquid contained in the second tank 2, with 10,000 times being particularly preferable. [Explanation of Symbols]
[0031] 1. Tank No. 1 2. Second Tank 3,5 Liquid supply port 4.6 Piping
Claims
1. A storage tank having a first tank and a second tank surrounding the first tank is used. A method for storing radioactive liquid in the first tank and the second tank, A method for storing radioactive liquids, wherein the radioactive liquid stored in the second tank has a lower radiation level than the radioactive liquid stored in the first tank.
2. The method for storing radioactive liquid according to claim 1, wherein the radiation dose of the radioactive liquid in the first tank is 1,000 to 20,000 times the radiation dose of the radioactive liquid in the second tank.
3. The method for storing a radioactive liquid according to claim 1 or 2, wherein the radioactive liquid is radioactive wastewater.
4. The second tank has a cylindrical portion that forms the side surface of the tank, and a bottom plate and a top plate that form the bottom and top surfaces of the tank. The first tank is cylindrical and is coaxially arranged inside the second tank. The method for storing radioactive liquid according to claim 3, wherein the bottom surface of the first tank and the bottom surface of the second tank are made of a common bottom plate.
5. The radiation dose of the radioactive liquid contained in the first tank was 6.67 × 10¹⁴ Cs-134. ５ Bq, Cs-137: 2.0 × 10 ７ It is Bq, The diameter of the first tank is 600 to 1000 mm. The method for storing a radioactive liquid according to claim 4, wherein the distance between the outer surface of the first tank and the inner surface of the second tank is 500 to 1000 mm.