Method for processing radioactive waste and storage device

Abstract

To enable long-term storage of radioactive waste, and provide a technique for properly neutralizing the stored radioactive waste.SOLUTION: A method for processing radioactive waste includes: a dehydration step of supplying a slurry containing radioactive waste into a storage container and dehydrating the slurry in the storage container; a storage step of storing the dehydrated radioactive waste in the storage container; a removal step of taking out the radioactive waste stored in the storage container during the storage step; and a heat treatment step of performing heat treatment on the radioactive waste taken out from the storage container in the removal step.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to a method for treating radioactive waste and a storage device. [Background technology]

[0002] One known example of radioactive waste is ion exchange resin, which is used in facilities that handle radioactive materials. In facilities that handle radioactive materials, large amounts of ion exchange resin are used to purify system water and water to be injected into the system in order to prevent corrosion of equipment. Radioactive waste (e.g., ion exchange resin) after use is stored in a storage tank. For example, Patent Document 1 discloses an apparatus for dehydrating and storing radioactive waste. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2017-096955 Summary of the Invention [Problem to be solved by the invention]

[0004] When radioactive waste is dehydrated and stored using a device such as that described in Patent Document 1, maintenance during storage is easier and it can be stored for a long period of time compared to undehydrated slurry-like radioactive waste. However, radioactive waste ultimately needs to be treated to render it harmless, but conventional technology has not considered how to render radioactive waste harmless after storage.

[0005] This specification discloses a technology that enables radioactive waste to be stored for a long period of time and also allows the stored radioactive waste to be appropriately detoxified. [Means for solving the problem]

[0006] A radioactive waste treatment method according to a first aspect of the technology disclosed in this specification comprises a dehydration process in which a slurry containing radioactive waste is supplied to a storage container and the slurry is dehydrated in the storage container; a storage process in which the radioactive waste dehydrated in the dehydration process is stored in the storage container; an extraction process in which the radioactive waste stored in the storage process is extracted from the storage container; and a heat treatment process in which the radioactive waste extracted from the storage container in the extraction process is heat treated.

[0007] In the above-described radioactive waste treatment method, the radioactive waste is dehydrated and stored in a storage container. Therefore, the radioactive waste stored in the storage container can be easily transported by transporting the storage container. Furthermore, the radioactive waste stored in the storage container is removed from the storage container after storage and subjected to thermal treatment. Therefore, the stored radioactive waste can be finally detoxified appropriately.

[0008] Furthermore, a storage device according to a first aspect of the technology disclosed in this specification is a storage device for dehydrating and storing a slurry containing radioactive waste using the radioactive waste treatment method described above. The storage device includes a storage container for dehydrating and storing the slurry, a decompression device for decompressing the storage container so as to move the slurry into the storage container, a filter disposed in the storage container that allows water to pass but not radioactive waste to pass through, and a drainage device for discharging water from the storage container to the outside via the filter. The storage container includes an inner container for storing radioactive waste and an outer container for storing the inner container. The inner container includes a water inlet for injecting water into the inner container and an outlet for removing the slurry containing the water injected from the water inlet and the radioactive waste in the inner container to the outside of the inner container. A filter is disposed inside the inner container.

[0009] In the above storage device, the provision of a pressure reducing device makes it easier to supply the slurry containing radioactive waste to the storage container. Furthermore, the provision of a filter and a drainage device makes it possible to properly dehydrate the slurry in the storage container. Furthermore, because the radioactive waste is dehydrated and stored in the storage container, the radioactive waste (i.e., the storage container) can be easily transported and stored. Furthermore, because the storage container has a water inlet and an outlet, when removing the radioactive waste after storage, the radioactive waste can be returned to the slurry, making it easier to remove the radioactive waste from the storage container. Furthermore, the storage container has an inner container with a water inlet and an outlet, and an outer container. In other words, the outer container does not have a water inlet or an outlet. Therefore, it is possible to avoid a complex external shape of the storage container (external shape of the outer container), making it easier to transport the storage container. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a diagram showing a schematic configuration of a storage device according to a first embodiment. [Figure 2] FIG. 2 is a diagram showing the configuration of a storage container. [Figure 3] FIG. [Figure 4] 1 is a flow chart illustrating an example of a method for treating radioactive waste in slurry form. [Figure 5] 10 is a flowchart showing an example of a process for storing radioactive waste. [Figure 6] 10 is a flowchart showing an example of a radioactive waste removal process. [Figure 7] FIG. 10 is a diagram showing a schematic configuration of a storage device according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] The main features of the embodiments described below are listed below. Note that the technical elements described below are independent technical elements that exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing.

[0012] In a radioactive waste treatment method according to a second aspect of the technology disclosed herein, in the radioactive waste treatment method according to the first aspect described above, the dehydration step may include a first supply step of supplying the slurry to a dehydration container, a first dehydration step of transferring water from the dehydration container to the outside, a second supply step of supplying the slurry from the dehydration container to a storage container, and a second dehydration step of further dehydrating the slurry supplied to the storage container in the second supply step within the storage container. With this configuration, the slurry can be dehydrated more reliably because it is dehydrated in two stages via the dehydration container.

[0013] In a radioactive waste treatment method according to a third aspect of the technology disclosed herein, in the radioactive waste treatment method according to the second aspect, the second supply step may include reducing the pressure of the storage container relative to the dehydration container and supplying the slurry from the dehydration container to the storage container. This configuration makes it easier to supply the slurry to the storage container.

[0014] In a radioactive waste treatment method according to a fourth aspect of the technology disclosed herein, in the radioactive waste treatment method according to the third aspect, in the second dehydration step, the dehydration container may be decompressed relative to the storage container to transfer the water in the storage container to the dehydration container. With this configuration, the water in the storage container can be dehydrated in an appropriate manner.

[0015] In a radioactive waste treatment method according to a fifth aspect of the technology disclosed in this specification, in the radioactive waste treatment method according to the third aspect described above, in the second dehydration step, the pressure in the drainage container may be reduced relative to the storage container, and the water in the storage container may be moved to the drainage container.

[0016] A radioactive waste treatment method according to a sixth aspect of the technology disclosed in this specification, which is any one of the radioactive waste treatment methods according to the first to fifth aspects described above, may further include a transfer step of transferring a storage container containing the radioactive waste dehydrated in the dehydration step to a storage location for storage in the storage step. According to this configuration, the radioactive waste is dehydrated and stored in the storage container, which makes it easier to transfer the storage container (i.e., the radioactive waste contained in the container) to the storage location, and the radioactive waste can be stored in an appropriate location.

[0017] In a radioactive waste treatment method according to a seventh aspect of the technology disclosed herein, in any one of the radioactive waste treatment methods according to the first to sixth aspects, the removal step may include a water pouring step of pouring water into the storage container, and a transfer step of transferring a slurry containing the water poured in the water pouring step and the radioactive waste stored in the storage container to the outside of the storage container. According to this configuration, by converting the radioactive waste into a slurry in the removal step, the radioactive waste (i.e., the slurry) can be easily removed from the storage container.

[0018] In a radioactive waste treatment method according to an eighth aspect of the technology disclosed in this specification, in the radioactive waste treatment method according to the seventh aspect, in the transfer step, the slurry transfer container may be depressurized relative to the storage container, and the slurry in the storage container may be transferred to the slurry transfer container. With this configuration, the slurry in the storage container can be easily transferred to the outside of the storage container.

[0019] In a storage device according to a second aspect of the technology disclosed in this specification, the outer container may be configured to be able to accommodate a plurality of inner containers in the storage device according to the first aspect. With this configuration, a single outer container can accommodate a plurality of inner containers, making it possible to simultaneously transport many inner containers.

[0020] In a storage device according to a third aspect of the technology disclosed in this specification, in the storage device according to the first or second aspect described above, the outer container may have a shielding structure that shields radiation. According to this configuration, by storing the inner container in the outer container, the storage container can be transported outside the facility. Furthermore, the inner container is provided with a water inlet and an outlet. Therefore, when storing radioactive waste in the storage container or removing radioactive waste from the storage container, the inner container can be removed from the outer container and work can be performed on the inner container. This prevents the radiation shielding structure from making it difficult to perform work on the storage container (i.e., the inner container). Furthermore, if the facility has a shielding structure, the inner container can be stored alone without the outer container, thereby increasing the amount of radioactive waste that can be stored in the facility. [Example]

[0021] Example 1 A storage device 10 according to an embodiment will be described with reference to the drawings. The storage device 10 is used to dehydrate and store a slurry containing radioactive waste. In this embodiment, the radioactive waste is, for example, an ion exchange resin used in a facility that handles radioactive materials. The used radioactive waste (e.g., ion exchange resin) is in the form of a slurry and is stored in a storage tank 2. The radioactive waste is eventually rendered harmless, but the detoxification process may be carried out a long time after the waste has been stored in the storage tank 2. By using the storage device 10, the slurry containing radioactive waste can be dehydrated and stored. This makes it easier to store radioactive waste for long periods of time.

[0022] As shown in FIG. 1, the storage device 10 includes a storage container 20 and a reduced pressure dehydration device 50.

[0023] The storage container 20 is a container for storing radioactive waste. Specifically, the storage container 20 dehydrates a slurry containing radioactive waste and stores the dehydrated radioactive waste. As shown in FIG. 2, the storage container 20 includes an inner container 22 and an outer container 40.

[0024] As shown in Fig. 3, the inner container 22 includes an inner main body portion 24 and an inner lid portion 26. The inner main body portion 24 is a substantially cylindrical box-shaped portion with an open top. The inner lid portion 26 is connected to the top surface of the inner main body portion 24. Radioactive waste is stored in the space formed by the inner main body portion 24 and the inner lid portion 26. In this embodiment, the inner container 22 (i.e., the inner main body portion 24 and the inner lid portion 26) does not have a shielding structure that blocks radiation.

[0025] The inner lid 26 is provided with a drain outlet 30, a water supply port 32, and a connection part 34 to which a path for transferring a slurry containing radioactive waste is connected. When supplying radioactive waste into the storage container 20 (i.e., the inner container 22), one end of a first drainage path 60 (see FIG. 1) is connected to the drain outlet 30, and one end of a first slurry supply path 62 (see FIG. 1) is connected to the connection part 34. When removing radioactive waste from the storage container 20 (i.e., the inner container 22), one end of a water supply path (not shown) is connected to the water supply port 32, and one end of a slurry removal path (not shown) is connected to the connection part 34.

[0026] A filter 28 and a drain pipe 29 are arranged inside the inner container 22. The filter 28 is arranged near the inner surface of the bottom of the inner main body portion 24. The filter 28 is configured to allow water to pass through but not allow radioactive waste (e.g., ion exchange resin, etc.) to pass through. One end of the drain pipe 29 is connected to the filter 28, and the other end is connected to a drain outlet 30. The drain pipe 29 discharges water from the inner container 22 that has passed through the filter 28 via the drain outlet 30 and a first drain path 60 to the outside of the inner container 22 (specifically, to the dehydration container 52, which will be described later).

[0027] The outer container 40 includes an outer main body portion 42 and an outer lid portion 44. The outer main body portion 42 is shaped like a substantially cylindrical box and has an open top. The outer lid portion 44 is detachably attached to the top surface of the outer main body portion 42. The outer main body portion 42 is configured to be able to accommodate an inner container 22 therein. That is, the inner diameter of the outer main body portion 42 is larger than the outer diameter of the inner container 22, and in this embodiment, the outer main body portion 42 is configured to accommodate one inner container 22. Furthermore, the height dimension of the outer main body portion 42 (more specifically, the distance from the upper surface of the bottom of the outer main body portion 42 to the upper end of the side surface) is larger than the height dimension of the inner container 22.

[0028] The outer main body 42 and the outer lid 44 have a shielding structure that blocks radiation. The shielding structure is a structure that blocks radiation emitted from radioactive waste (i.e., radioactive waste stored in the storage container 20 in this embodiment). For example, the outer main body 42 and the outer lid 44 are formed from a material that is difficult for radiation to pass through, and are formed to a thickness that allows for radiation shielding.

[0029] The outer container 40 (i.e., the outer main body 42 and the outer lid 44) ​​has a shielding structure, which prevents radiation emitted from the radioactive waste in the outer container 40 (specifically, the radioactive waste in the inner container 22 housed in the outer container 40) from leaking outside the outer container 40. Therefore, by storing radioactive waste in the storage container 20 (specifically, the inner container 22 housed in the outer container 40), the radioactive waste in the storage container 20 can be transported outside a facility having a shielding structure. Furthermore, by making the storage container 20 a double structure consisting of the inner container 22 and the outer container 40, it is possible to store the radioactive waste (inner container 22) by placing only the inner container 22 in a storage facility (limited to facilities having a shielding structure). The outer container 40 has a large outer diameter due to its shielding structure. By placing only the inner container 22 in a storage facility, it is possible to place more inner containers 22 in the storage facility, and therefore to store more radioactive waste in the storage facility. Furthermore, since only the inner container 22 without a shielding structure can be placed in the storage facility, the capacity of the storage facility can be reduced.

[0030] In this embodiment, the outer container 40 is configured to accommodate one inner container 22, but is not limited to this configuration. For example, the outer container may be configured to accommodate multiple inner containers 22. By accommodating multiple inner containers 22 in one outer container, many inner containers 22 can be transported simultaneously. Furthermore, the thickness of the outer container 40 may be set according to the type of radiation emitted from the radioactive waste stored in the storage container 20 (i.e., the inner container 22). In this embodiment, the storage container 20 has a double structure. Therefore, by appropriately setting the thickness of the outer container 40, it is possible to appropriately accommodate the storage and transportation of radioactive waste containing various radioactive materials without changing the shape of the inner container 22.

[0031] As shown in Fig. 1, the reduced pressure dehydration apparatus 50 is an apparatus used to dehydrate a slurry containing radioactive waste and store it in a storage container 20. The reduced pressure dehydration apparatus 50 includes a dehydration container 52 and a decompression device 56.

[0032] The dehydration vessel 52 receives the radioactive waste slurry stored in the storage tank 2 and supplies the received radioactive waste slurry to the storage vessel 20. A filter 54 is disposed inside the dehydration vessel 52. The filter 54 is configured to allow water to pass through but not allow radioactive waste (e.g., ion exchange resin, etc.) to pass through.

[0033] A second slurry supply path 64 and a second drainage path 66 are provided between the dehydration vessel 52 and the storage tank 2. A pump 65 is installed in the second slurry supply path 64. By operating the pump 65, the second slurry supply path 64 supplies the slurry containing radioactive waste in the storage tank 2 to the dehydration vessel 52. The end of the second drainage path 66 on the dehydration vessel 52 side is connected to a filter 54. When slurry or water is supplied into the dehydration vessel 52 from the outside (storage tank 2 or storage vessel 20), the water in the dehydration vessel 52 is sent to the second drainage path 66 via the filter 54. The water sent to the second drainage path 66 moves to the storage tank 2.

[0034] A first drainage path 60 and a first slurry supply path 62 are provided between the dehydration vessel 52 and the storage vessel 20. The dehydration vessel 52 supplies radioactive waste in a slurry state to the storage vessel 20 via the first slurry supply path 62. The dehydration vessel 52 also receives water from within the storage vessel 20 via the first drainage path 60.

[0035] Decompression device 56 is a vacuum pump and can separately decompress the space within dehydration container 52 and the space within storage container 20. Decompression device 56 is connectable to a first decompression path 68 that connects to storage container 20, and is also connectable to a second decompression path 70 that connects to dehydration container 52. When decompression device 56 is operated while connected to first decompression path 68, the space within storage container 20 is decompressed via first decompression path 68. When decompression device 56 is operated while connected to second decompression path 70, the space within dehydration container 52 is decompressed via second decompression path 70.

[0036] Next, a method for treating slurry-like radioactive waste will be described. As described above, the slurry-like radioactive waste may be subjected to detoxification treatment after a long period of time has passed. In this embodiment, the slurry-like radioactive waste is dehydrated and stored to facilitate long-term storage of the radioactive waste.

[0037] As shown in Fig. 4, first, the radioactive waste storage step is carried out (S10). The radioactive waste storage step is a step of dehydrating the radioactive waste slurry stored in the storage tank 2 and storing it in the storage container 20. In this embodiment, the storage container 20 has a double structure of an inner container 22 and an outer container 40. The radioactive waste storage step is carried out, for example, with the inner container 22 stored in the outer main body 42 and the outer lid 44 removed.

[0038] The radioactive waste storage process is performed in the following procedure. As shown in FIG. 5, first, each component of the storage apparatus 10 is arranged near the storage tank 2 (S100). That is, the storage apparatus 10 of this embodiment is not installed in a fixed position, but is removably installed near the storage tank 2 to be treated. For this reason, first, the storage apparatus 10 is installed near the storage tank 2, and the radioactive waste in the storage tank 2 is made treatable. Specifically, a reduced pressure dehydration apparatus 50 is installed near the storage tank 2, and a second slurry supply path 64 and a second drainage path 66 are connected between the dehydration vessel 52 and the storage tank 2. In addition, a storage vessel 20 is installed, and a first drainage path 60 and a first slurry supply path 62 are connected between the storage vessel 20 and the dehydration vessel 52. In addition, a first reduced pressure path 68 is connected to the storage vessel 20.

[0039] Next, the slurry-like radioactive waste contained in the storage tank 2 is supplied to the dehydration vessel 52 (S110). Specifically, the pump 65 is operated. Then, the slurry-like radioactive waste is supplied from the storage tank 2 to the dehydration vessel 52 via the second slurry supply path 64. Also, the water in the dehydration vessel 52 is sent to the second drainage path 66 via the filter 54 and moves to the storage tank 2 (S120). As a result, the concentrated slurry-like radioactive waste is contained in the dehydration vessel 52.

[0040] In this embodiment, the water discharged from dehydration vessel 52 in step S120 is returned to storage tank 2, but the present invention is not limited to this configuration. For example, the water discharged from dehydration vessel 52 may be discarded without being returned to storage tank 2, or may be sent to another treatment device (not shown) and subjected to detoxification treatment therein before being discarded.

[0041] Next, the space inside the storage container 20 is depressurized (130). Specifically, the depressurization device 56 is operated while connected to the first depressurization path 68. Then, the space inside the storage container 20 is depressurized via the first depressurization path 68.

[0042] Next, the slurry-like radioactive waste supplied into the dehydration vessel 52 in step S110 is moved to the storage vessel 20 via the first slurry supply path 62 (S140). In step S130, the space within the storage vessel 20 is depressurized. Therefore, a pressure difference occurs between the space within the storage vessel 20 and the space within the dehydration vessel 52. Due to the pressure difference between the space within the storage vessel 20 and the space within the dehydration vessel 52, the slurry-like radioactive waste can be easily moved from the dehydration vessel 52 to the storage vessel 20.

[0043] When the slurry-like radioactive waste is moved from the dehydration vessel 52 to the storage vessel 20, the space within the dehydration vessel 52 is depressurized (S150). Specifically, the depressurization device 56 is operated while connected to the second depressurization path 70. Then, the space within the dehydration vessel 52 is depressurized via the second depressurization path 70. Note that the space within the storage vessel 20 is opened to the atmosphere, and the pressure therein is made higher than that of the space within the dehydration vessel 52.

[0044] Next, water in the storage container 20 is moved to the dehydration container 52 via the first drainage path 60 (S160). As described above, in step S150, the space in the dehydration container 52 is depressurized, creating a pressure difference between the space in the storage container 20 and the space in the dehydration container 52. The pressure difference between the space in the storage container 20 and the space in the dehydration container 52 facilitates the movement of water from the storage container 20 to the dehydration container 52. The first drainage path 60 is also connected to the filter 28 via the drain outlet 30 and the drain pipe 29. Therefore, only water that can pass through the filter 28 moves to the dehydration container 52 via the drain pipe 29, the drain outlet 30, and the first drainage path 60, while radioactive waste that cannot pass through the filter 28 (in this embodiment, ion exchange resin) remains in the storage container 20. Because only the water in the storage container 20 moves to the dehydration container 52, the slurry-like radioactive waste is dehydrated in the storage container 20. The water that has moved into the dehydration vessel 52 is sent to the second drainage path 66 via the filter 54 and moves to the storage tank 2.

[0045] In this embodiment, the water moved into dehydration vessel 52 in step S160 is returned to storage tank 2, but the present invention is not limited to this configuration. For example, the water moved into dehydration vessel 52 may be discarded without being returned to storage tank 2, or may be sent to another treatment device (not shown) and subjected to detoxification treatment therein before being discarded.

[0046] Next, it is determined whether the storage container 20 is full with radioactive waste (S170). Since the water in the storage container 20 is drained in step S160, the amount of contents (i.e., radioactive waste) in the storage container 20 decreases by the amount of water drained. If the storage container 20 is not full (NO in step S170), the process returns to step S110, and steps S110 to S170 are repeated until the storage container 20 is full. If the storage container 20 is full (YES in step S170), the first drainage path 60, the first slurry supply path 62, and the first decompression path 68 are removed from the storage container 20 (S180). Next, the outer lid 44 is attached to the outer main body 42 (S190). Thereafter, the process proceeds to step S12 of FIG. 4.

[0047] As shown in FIG. 4, after the radioactive waste accommodation step of step S10 is completed, a transfer step of the storage container 20 is performed (S12). In the transfer step of step S12, the storage container 20 is transferred from the location where the storage tank 2 is installed to a storage facility. The outer container 40 has a shielding structure that blocks radiation. Therefore, the storage container 20 can be transferred from the location where the storage tank 2 is installed to the storage facility. In this embodiment, the storage facility has a shielding structure. When the storage container 20 is transferred to the storage facility, the inner container 22 is removed from the outer container 40. Then, only the inner container 22 is placed in the storage facility. Since only the inner container 22 is placed in the storage facility, many inner containers 22 can be placed in the storage facility. In other words, many radioactive wastes can be stored in the storage facility. Furthermore, since the outer container 40 is not stored in the storage facility, it can be repeatedly used in the radioactive waste accommodation step of step S10 and the storage container transfer step of step S12. Therefore, the number of outer containers 40 can be reduced. The outer container 40 has a shielding structure, which increases manufacturing costs. Reducing the number of outer containers 40 reduces the cost of the storage container 20. If the storage facility does not have a shielding structure, the inner container 22 may be placed in the storage facility while still housed in the outer container 40, without being removed from the outer container 40.

[0048] Once the transfer process of the storage container 20 is completed, the radioactive waste is stored in the storage facility while contained within the inner container 22 (or storage container 20) until the radioactive waste is detoxified (specifically, the heat treatment process described below) (S14).

[0049] When the storage period ends, a transfer step of the storage container 20 is performed (S16). In the transfer step of step S16, the storage container 20 is transferred from the storage facility to the heat treatment facility. In the transfer step of step S16, first, the inner container 22 placed in the storage facility is housed in the outer container 40. The outer container 40 has a shielding structure. By housing the inner container 22 in the outer container 40, the storage container 20 (i.e., the radioactive waste housed in the storage container 20) can be transported outside the storage facility. Note that if the storage container 20 is placed in the storage facility without removing the inner container 22, the process of housing the inner container 22 in the outer container 40 is omitted. Thereafter, the storage container 20 is transported from the storage facility to the heat treatment facility.

[0050] Next, the radioactive waste removal step is carried out (S18). The radioactive waste removal step is a step of removing the radioactive waste contained in the storage container 20 from the storage container 20.

[0051] The radioactive waste removal process is carried out in the following procedure. As shown in Fig. 6, first, the outer lid part 44 is removed from the storage container 20 (S200). Next, a water supply path (not shown) and a slurry removal path (not shown) are connected to the storage container 20 (S210). The water supply path is connected to the water supply port 32, and the slurry removal path is connected to the connection part 34.

[0052] Next, water is poured into the storage container 20 via the water supply path (S220). Dehydrated radioactive waste is contained within the storage container 20. For this reason, the radioactive waste within the storage container 20 is solidified and is difficult to remove from the storage container 20 as is. By pouring water into the storage container 20, the radioactive waste becomes a slurry, making it easier to remove from the storage container 20. Next, the slurry radioactive waste is removed from the storage container 20 via the slurry removal path (S230). Thereafter, the process proceeds to step S20 in FIG. 4.

[0053] In the process of removing the slurry-like radioactive waste from the storage container 20 in step S230, the radioactive waste may be removed from the storage container 20 using the decompression device 56 of the storage apparatus 10. Specifically, the decompression device 56 and a slurry transfer container (not shown) are installed near the storage container 20. The slurry transfer container is a container for storing the slurry removed from the storage container 20. The slurry transfer container may be a tank provided in a heat treatment furnace, which will be described later. Next, a decompression path (not shown) is connected between the slurry transfer container and the decompression device 56, and a slurry removal path (not shown) is connected between the slurry transfer container and the storage container 20 (specifically, the connection part 34). Next, the decompression device 56 is operated to reduce the pressure in the space within the slurry transfer container. Next, the slurry-like radioactive waste in the storage container 20 is transferred to the slurry transfer container via the slurry removal path. By reducing the pressure in the space inside the slurry transfer container, a pressure difference occurs between the space inside the slurry transfer container and the space inside the storage container 20. This makes it possible to easily transfer the slurry-like radioactive waste from the storage container 20 to the slurry transfer container.

[0054] As shown in Fig. 4, once the radioactive waste removal process is completed, a heat treatment process for the radioactive waste is carried out (S20). The heat treatment process is not particularly limited as long as it can thermally treat the radioactive waste to render it harmless. For example, the heat treatment process can be carried out using a bowl-type heat treatment furnace equipped with a dry distillation section (for example, the heat treatment furnace disclosed in JP 2015-72132 A).

[0055] Example 2 In the above-described first embodiment, when the slurry-like radioactive waste in the storage container 20 is dehydrated, the water in the storage container 20 is returned to the dehydration container 52, but this configuration is not limited to this. For example, the water in the storage container 20 may be discharged into another container instead of being returned to the dehydration container 52.

[0056] 7, the storage device 110 includes a storage container 20, a reduced pressure dehydration device 50, and a drainage container 58. The configurations of the storage container 20 and the reduced pressure dehydration device 50 are substantially the same as those of the storage container 20 and the reduced pressure dehydration device 50 of the first embodiment, and therefore detailed description thereof will be omitted.

[0057] The drainage container 58 receives water discharged from the storage container 20. A first drainage path 160 is provided between the drainage container 58 and the storage container 20. The end of the first drainage path 160 on the storage container 20 side is connected to the filter 28. The drainage container 58 receives water from the storage container 20 via the first drainage path 160. In addition, a second decompression path 170 is provided between the drainage container 58 and the pressure reducing device 56. When the pressure reducing device 56 is operated while connected to the second decompression path 170, the space within the drainage container 58 is decompressed via the second decompression path 170.

[0058] In this embodiment, a method for treating slurry radioactive waste will be described. In this embodiment, only the processing of steps S150 and S160 of the radioactive waste accommodation step in Fig. 5 differs from the method for treating slurry radioactive waste in the above-mentioned embodiment 1, and the other steps are similar to the method for treating slurry radioactive waste in the above-mentioned embodiment 1. Therefore, the processing of steps S150 and S160 will be described below, and detailed descriptions of the processing of the other steps will be omitted.

[0059] In this embodiment, in step S150, the space in drainage container 58 is depressurized instead of the space in spin container 52. Specifically, depressurization device 56 is operated while connected to second depressurization path 170. Then, the space in drainage container 58 is depressurized via second depressurization path 170.

[0060] Next, in step S160, instead of moving the water in the storage container 20 to the dehydration container 52, the water in the storage container 20 is moved to the drainage container 58 via the first drainage path 160. In step S150, the space in the drainage container 58 is depressurized. Therefore, water can be easily moved from the storage container 20 to the dehydration container 52 via the first drainage path 160. Therefore, in this embodiment as well, the slurry-like radioactive waste can be appropriately dehydrated in the storage container 20.

[0061] In the above-described first and second embodiments, the storage container 20 has a double structure including the inner container 22 and the outer container 40, but is not limited to this configuration. The storage container does not have to have the outer container 40. In this case, the storage container has substantially the same structure as the inner container 22 of the above-described first and second embodiments, and also has a shielding structure. Since the storage container has substantially the same structure as the inner container 22, radioactive waste can be dehydrated and stored in the storage container, and the radioactive waste stored in the storage container can be appropriately removed. Furthermore, since the storage container has a shielding structure, the storage container can be transported outside a facility having a shielding structure, even if it does not have a double structure.

[0062] The following points should be noted regarding the storage device 10 described in the embodiment. The first drainage path 60 and the drainage pipe 29 in the embodiment are an example of a "drainage device."

[0063] Although specific examples of the technology disclosed in this specification have been described in detail above, these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and variations of the specific examples exemplified above. Furthermore, the technical elements described in this specification or drawings exhibit technical utility alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Furthermore, the technology exemplified in this specification or drawings simultaneously achieves multiple objectives, and achieving one of those objectives itself has technical utility. [Explanation of symbols]

[0064] 2: Storage tank 10, 110: Storage device 20: Storage container 22: Inner container 28: Filter 29: Drain pipe 30: Drain port 32: Water supply port 34: Connection 40:Outer container 42:Outer body part 44:Outer lid part 50: Decompression dehydration device 52: Dehydration container 56: Pressure reducing device 58: Drainage container 60, 160: First drainage route 62: First slurry supply path 64: Second slurry supply route 66: Second drainage route 68: First decompression route 70, 170: Second decompression route

Claims

1. 1. A method for treating radioactive waste, comprising: a dehydration step of supplying the slurry containing the radioactive waste to a storage container and dehydrating the slurry in the storage container; a storage step of storing the radioactive waste dehydrated in the dehydration step in the storage container; a removal step of removing the radioactive waste stored in the storage step from the storage container; a heat treatment step of heat treating the radioactive waste removed from the storage container in the removal step; A method for treating radioactive waste, comprising:

2. The dehydration step includes: a first supply step of supplying the slurry to a dehydration vessel; a first dehydration step of transferring water from the dehydration container to the outside; a second supply step of supplying the slurry in the dehydration container to the storage container; a second dehydration step of further dehydrating the slurry supplied to the storage container in the second supply step within the storage container; The method for treating radioactive waste according to claim 1, comprising:

3. 3. The method for treating radioactive waste according to claim 2, wherein in the second supplying step, the storage container is depressurized relative to the dehydration container, and the slurry is supplied from the dehydration container to the storage container.

4. 4. The method for treating radioactive waste according to claim 3, wherein in the second dehydration step, the pressure in the dehydration container is reduced relative to the storage container, thereby moving water in the storage container to the dehydration container.

5. 4. The method for treating radioactive waste according to claim 3, wherein in the second dehydration step, the pressure in the drainage container is reduced relative to the storage container, thereby moving the water in the storage container to the drainage container.

6. 2. The method for treating radioactive waste according to claim 1, further comprising a transfer step of transferring the storage container containing the radioactive waste dehydrated in the dehydration step to a storage location for storing the radioactive waste in the storage step.

7. The removing step includes: A water injection step of injecting water into the storage container; a transfer step of transferring a slurry containing the water injected in the water injection step and the radioactive waste stored in the storage container to the outside of the storage container; 2. The method for treating radioactive waste according to claim 1, comprising:

8. 8. The radioactive waste treatment method according to claim 7, wherein in the transferring step, the slurry in the storage container is transferred to the slurry transfer container by reducing the pressure of the slurry transfer container relative to the storage container.

9. A storage device for dehydrating and storing a slurry containing radioactive waste using the radioactive waste treatment method according to claim 1, A storage container for dehydrating and storing the slurry; a decompression device that reduces the pressure inside the storage container so as to move the slurry into the storage container; a filter disposed within the storage container that allows water to pass through but does not allow the radioactive waste to pass through; a drainage device that discharges water from the storage container to the outside through the filter, The storage container comprises: an inner container for containing the radioactive waste; an outer container that houses the inner container, The inner container comprises: a water inlet for injecting water into the inner container; an outlet for taking out a slurry containing the water injected from the water inlet and the radioactive waste in the inner container to the outside of the inner container; It is equipped with The storage device, wherein the inner container has the filter disposed therein.

10. The storage device according to claim 9 , wherein the outer container is configured to accommodate a plurality of the inner containers.

11. The storage device according to claim 9 or 10, wherein the outer container has a shielding structure for shielding against radiation.

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