Method for treating radioactive waste and storage device

Abstract

Provided is a technique that enables long-term storage of radioactive waste and appropriately detoxifies the stored radioactive waste. 【Solution means】A method for treating radioactive waste includes a dehydration step of supplying a slurry containing 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, and a heat treatment step of heat-treating the radioactive waste removed from the storage container in the removal step.

Description

Technical Field

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

Background Art

[0002] As radioactive waste, for example, ion exchange resins used in facilities that handle radioactive substances are known. In facilities that handle radioactive substances, a large amount of ion exchange resin is used for purifying system water and the water injected into the system in order to prevent corrosion of equipment. The radioactive waste (for example, 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

Summary of the Invention

Problems to be Solved by the Invention

[0004] When radioactive waste is dehydrated and stored using an apparatus such as that of Patent Document 1, maintenance during storage becomes easier and long-term storage becomes possible as compared with non-dehydrated slurry-like radioactive waste. However, radioactive waste ultimately needs to be subjected to treatment for detoxification, but the prior art has not considered the detoxification treatment of radioactive waste after storage.

[0005] This specification discloses a technology that enables long-term storage of radioactive waste and appropriately detoxifies the stored radioactive waste.

Means for Solving the Problems

[0006] The method for treating radioactive waste according to the first aspect of the technology disclosed in this specification includes a dehydration step of supplying a slurry containing 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, and a heat treatment step of heat-treating the radioactive waste removed from the storage container in the removal step.

[0007] In the above method for treating radioactive waste, the radioactive waste is dehydrated and stored in a storage container. Therefore, by transporting the storage container as a whole, the radioactive waste stored in the storage container can be easily transported. In addition, the radioactive waste stored in the storage container is taken out of the storage container and heat-treated after storage. Therefore, the stored radioactive waste can be finally appropriately detoxified.

[0008] Further, the storage device according to the first aspect of the technology disclosed in this specification is a storage device for dehydrating and storing a slurry containing radioactive waste using the above method for treating radioactive waste. The storage device includes a storage container for dehydrating and storing the slurry, a decompression device for decompressing the inside of the storage container so as to move the slurry into the storage container, a filter disposed in the storage container for allowing water to pass through and not allowing radioactive waste to pass through, and a drainage device for discharging the water inside the storage container to the outside through the filter. The storage container includes an inner container for accommodating radioactive waste and an outer container for accommodating the inner container. The inner container includes a water injection port for injecting water into the inner container and an outlet for taking out a slurry containing the water injected from the water injection port and the radioactive waste inside the inner container to the outside of the inner container. A filter is disposed inside the inner container.

[0009] In the above-described storage device, by providing a decompression device, it is possible to easily supply the slurry containing radioactive waste to the storage container. Further, by providing a filter and a drainage device, the slurry in the storage container can be appropriately dehydrated. Further, since the radioactive waste is dehydrated and stored in the storage container, the radioactive waste (i.e., the storage container) can be easily transferred and stored. Further, since the storage container is provided with a water injection port and a take-out port, when taking out the radioactive waste after storage, the radioactive waste can be returned to the slurry, and the radioactive waste can be easily taken out from the storage container. Further, the storage container includes an inner container provided with a water injection port and a take-out port, and an outer container. That is, the outer container is not provided with a water injection port and a take-out port. Therefore, it is possible to avoid the outer shape of the storage container (the outer shape of the outer container) becoming a complicated structure, and the storage container can be easily transferred.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Modes for Carrying Out the Invention

[0011] The main features of the embodiments described below are listed. Note that the technical elements described below are each independent technical elements, and 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 the method for treating radioactive waste according to the second aspect of the technology disclosed in this specification, in the method for treating radioactive waste according to the first aspect described above, the dehydration process may include a first supply step of supplying the slurry to a dehydration container, a first dehydration step of moving the water in the dehydration container to the outside, a second supply step of supplying the slurry in the dehydration container to a storage container, and a second dehydration step of further dehydrating the slurry supplied to the storage container in the storage container. According to such a configuration, since dehydration is performed in two stages via the dehydration container, the slurry can be dehydrated more reliably.

[0013] In the method for treating radioactive waste according to the third aspect of the technology disclosed in this specification, in the method for treating radioactive waste according to the second aspect described above, in the second supply step, the storage container may be depressurized with respect to the dehydration container, and the slurry may be supplied from the dehydration container to the storage container. According to such a configuration, it becomes easier to supply the slurry to the storage container.

[0014] In the method for treating radioactive waste according to the fourth aspect of the technology disclosed in this specification, in the method for treating radioactive waste according to the third aspect described above, in the second dehydration step, the dehydration container may be depressurized with respect to the storage container, and the water in the storage container may be moved to the dehydration container. According to such a configuration, the water in the storage container can be suitably dehydrated.

[0015] In the method for treating radioactive waste according to the fifth aspect of the technology disclosed in this specification, in the method for treating radioactive waste according to the third aspect described above, in the second dehydration step, the drainage container may be depressurized with respect to the storage container, and the water in the storage container may be moved to the drainage container.

[0016] In the method for treating radioactive waste according to the sixth aspect of the technology disclosed in this specification, in any one of the methods for treating radioactive waste according to the first to fifth aspects described above, the method for treating radioactive waste may further include a transfer step of transferring a storage container that stores the radioactive waste dehydrated in the dehydration step to a storage location for storage in the storage step. According to such a configuration, since the radioactive waste is dehydrated and stored in the storage container, it becomes easier to transfer the storage container (that is, the radioactive waste contained in the container) to the storage location, and the radioactive waste can be stored in an appropriate location.

[0017] In the method for treating radioactive waste according to the seventh aspect of the technology disclosed in this specification, in any one of the methods for treating radioactive waste according to the first to sixth aspects described above, the extraction step may include a water injection step of injecting water into the storage container, and a moving step of moving a slurry containing the water injected in the water injection step and the radioactive waste stored in the storage container outside the storage container. According to such a configuration, in the extraction step, by making the radioactive waste into a slurry state, it becomes easier to extract the radioactive waste (that is, the slurry) from the storage container.

[0018] In the method for treating radioactive waste according to the eighth aspect of the technology disclosed in this specification, in the method for treating radioactive waste according to the seventh aspect described above, in the moving step, the storage container may be depressurized with respect to the slurry transfer container to transfer the slurry in the storage container to the slurry transfer container. According to such a configuration, it becomes easier to move the slurry in the storage container outside the storage container.

[0019] In the storage device according to the second aspect of the technology disclosed in this specification, in the storage device according to the first aspect described above, the outer container may be configured to be capable of accommodating a plurality of inner containers. According to such a configuration, a plurality of inner containers can be accommodated in one outer container, and many inner containers can be transferred simultaneously.

[0020] In the storage device according to the third aspect of the technology disclosed in this specification, in the storage device according to the above first or second aspect, the outer container may have a shielding structure for shielding radiation. According to such a configuration, by housing the inner container in the outer container, the storage container can be transferred outside the facility. Further, the water injection port and the take-out port are provided in the inner container. Therefore, when storing radioactive waste in the storage container or taking out radioactive waste from the storage container, the inner container can be taken out from the outer container and work can be performed on the inner container. Thus, it is possible to avoid the difficulty of performing work on the storage container (i.e., the inner container) due to the radiation shielding structure. Further, in a facility having a shielding structure, only the inner container can be housed in the facility without the outer container, and the amount of radioactive waste that can be housed in the facility can be increased.

Example

[0021] (Example 1) With reference to the drawings, the storage device 10 according to the example will be described. The storage device 10 is used to dehydrate and store a slurry containing radioactive waste. In this example, the radioactive waste is, for example, an ion exchange resin used in a facility that handles radioactive substances. The radioactive waste after use (for example, ion exchange resin) is in a slurry state and is stored in the storage tank 2. The radioactive waste is finally rendered harmless, but the detoxification process may be carried out after a long period has elapsed since it was stored in the storage tank 2. By using the storage device 10, the slurry containing radioactive waste can be dehydrated and stored. Therefore, it becomes easier to store radioactive waste for a long period of time.

[0022] As shown in FIG. 1, the storage device 10 includes a storage container 20 and a vacuum 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 in the shape of a substantially cylindrical box with an open upper surface. The inner lid portion 26 is connected to the upper surface of the inner main body portion 24. Radioactive waste is accommodated in the space formed by the inner main body portion 24 and the inner lid portion 26. In this embodiment, the inner container 22 (that is, the inner main body portion 24 and the inner lid portion 26) does not have a shielding structure for shielding radiation.

[0025] The inner lid portion 26 is provided with a drain port 30, a water supply port 32, and a connection portion 34 to which a path for moving the slurry containing radioactive waste is connected. When supplying radioactive waste into the storage container 20 (that is, the inner container 22), one end of the first drain path 60 (see FIG. 1) is connected to the drain port 30, and one end of the first slurry supply path 62 (see FIG. 1) is connected to the connection portion 34. When taking out radioactive waste from the storage container 20 (that is, 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 extraction path (not shown) is connected to the connection portion 34.

[0026] A filter 28 and a drain pipe 29 are arranged in the inner container 22. The filter 28 is arranged near the inner surface of the bottom surface of the inner main body portion 24. The filter 28 is configured to allow water to pass through while preventing radioactive waste (such as ion exchange resin, etc.) from passing through. One end of the drain pipe 29 is connected to the filter 28, and the other end is connected to the drain port 30. The drain pipe 29 discharges the water in the inner container 22 that has passed through the filter 28 to the outside of the inner container 22 (specifically, a dehydration container 52 described later) via the drain port 30 and the first drain path 60.

[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 in the shape of a substantially cylindrical box with an open upper surface. The outer lid portion 44 is detachably attached to the upper surface of the outer main body portion 42. The outer main body portion 42 is configured to be able to accommodate the inner container 22 therein. That is, the inner diameter of the outer main body portion 42 is made larger than the outer diameter of the inner container 22. In this embodiment, the outer main body portion 42 is configured to accommodate one inner container 22. Further, the dimension in the height direction of the outer main body portion 42 (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 made larger than the dimension in the height direction of the inner container 22.

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

[0029] Since the outer container 40 (i.e., the outer main body 42 and the outer lid 44) has a shielding structure, it is possible to prevent the radiation emitted from the radioactive waste inside the outer container 40 (specifically, the radioactive waste inside the inner container 22 housed in the outer container 40) from leaking outside the outer container 40. Therefore, by housing radioactive waste in the storage container 20 (specifically, the inner container 22 housed in the outer container 40), the radioactive waste inside the storage container 20 can be transferred outside the facility having the shielding structure. Further, by making the storage container 20 have a double structure of the inner container 22 and the outer container 40, only the inner container 22 can be arranged in a storage facility (however, limited to a facility having a shielding structure), and the radioactive waste (inner container 22) can be stored. Since the outer container 40 has a shielding structure, its outer diameter becomes large. By arranging only the inner container 22 in the storage facility, a large number of inner containers 22 can be arranged in the storage facility, and a large amount of radioactive waste can be stored in the storage facility. Also, since only the inner container 22 without a shielding structure can be arranged in the storage facility, the capacity of the storage facility can be reduced.

[0030] In this embodiment, the outer container 40 is configured to house one inner container 22, but it is not limited to such a configuration. For example, the outer container may be configured to be able to house a plurality of inner containers 22. By housing a plurality of inner containers 22 in one outer container, a large number of inner containers 22 can be transferred simultaneously. Also, the plate 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 plate thickness of the outer container 40, it is possible to appropriately respond to the storage and transfer of radioactive waste containing various radioactive substances without changing the shape of the inner container 22.

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

[0032] The dehydration container 52 receives the slurry-like radioactive waste stored in the storage tank 2 and supplies the received slurry-like radioactive waste to the storage container 20. A filter 54 is disposed inside the dehydration container 52. The filter 54 is configured such that water can pass through it while radioactive waste (e.g., ion exchange resin, etc.) cannot pass through it.

[0033] A second slurry supply path 64 and a second drainage path 66 are provided between the dehydration container 52 and the storage tank 2. A pump 65 is installed in the second slurry supply path 64. The second slurry supply path 64 supplies the slurry containing radioactive waste in the storage tank 2 to the dehydration container 52 by operating the pump 65. The end of the second drainage path 66 on the dehydration container 52 side is connected to the filter 54. When slurry or water is supplied to the inside of the dehydration container 52 from the outside (storage tank 2 or storage container 20), the water inside the dehydration container 52 passes through the filter 54 and is sent out to the second drainage path 66. The water sent out 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 container 52 and the storage container 20. The dehydration container 52 supplies the slurry-like radioactive waste to the storage container 20 through the first slurry supply path 62. Also, the dehydration container 52 receives the water inside the storage container 20 through the first drainage path 60.

[0035] The decompression device 56 is a vacuum pump and can individually decompress the spaces in the dehydration container 52 and the storage container 20. The decompression device 56 can be connected to a first decompression path 68 connected to the storage container 20 and can also be connected to a second decompression path 70 connected to the dehydration container 52. When the decompression device 56 operates with the decompression device 56 connected to the first decompression path 68, the space in the storage container 20 is decompressed via the first decompression path 68. Also, when the decompression device 56 operates with the decompression device 56 connected to the second decompression path 70, the space in the dehydration container 52 is decompressed via the 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 detoxified after a long period of time. In this embodiment, in order to make it easier to store the radioactive waste over a long period of time, the slurry-like radioactive waste is dehydrated and stored.

[0037] As shown in FIG. 4, first, a radioactive waste storage step is performed (S10). The radioactive waste storage step is a step of dehydrating the slurry-like radioactive waste 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 performed, for example, with the inner container 22 housed in the outer main body 42 and the outer lid 44 removed.

[0038] The process of containing radioactive waste is carried out according to the following procedure. As shown in Figure 5, first, each part of the storage device 10 is arranged near the storage tank 2 (S100). That is, the storage device 10 of this embodiment is not fixedly installed, but is removably installed and used near the storage tank 2 to be processed. Therefore, first, the storage device 10 is installed near the storage tank 2 to make the radioactive waste in the storage tank 2 in a processable state. Specifically, a vacuum dehydration device 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 container 52 and the storage tank 2. In addition, a storage container 20 is installed, and a first drainage path 60 and a first slurry supply path 62 are connected between the storage container 20 and the dehydration container 52. Further, a first vacuum path 68 is connected to the storage container 20.

[0039] Next, the slurry-like radioactive waste contained in the storage tank 2 is supplied to the dehydration container 52 (S110). Specifically, the pump 65 is operated. Then, the slurry-like radioactive waste is supplied from the storage tank 2 to the dehydration container 52 through the second slurry supply path 64. Also, the water in the dehydration container 52 is sent out to the second drainage path 66 through 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 container 52.

[0040] In this embodiment, the water sent out from the inside of the dehydration container 52 in step S120 is returned to the storage tank 2, but it is not limited to such a configuration. For example, the water sent out from the inside of the dehydration container 52 may not be returned to the storage tank 2 but may be discarded, or may be sent to another processing device (not shown) and discarded after being detoxified by another processing device.

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

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

[0043] When the slurry-like radioactive waste moves from the dehydration container 52 to the storage container 20, the space inside the dehydration container 52 is under reduced pressure (S150). Specifically, the decompression device 56 is operated while being connected to the second decompression path 70. Then, the space inside the dehydration container 52 is under reduced pressure via the second decompression path 70. Note that the space inside the storage container 20 is released to the atmosphere, and the pressure is made higher than that inside the dehydration container 52.

[0044] Next, the water inside 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 inside the dehydration container 52 is under reduced pressure, and a pressure difference is generated between the space inside the storage container 20 and the space inside the dehydration container 52. Due to the pressure difference between the space inside the storage container 20 and the space inside the dehydration container 52, the water can be easily moved from the storage container 20 to the dehydration container 52. Also, the first drainage path 60 is connected to the filter 28 via the drain port 30 and the drain pipe 29. Therefore, only the water that can pass through the filter 28 moves to the dehydration container 52 via the drain pipe 29, the drain port 30, and the first drainage path 60, and the radioactive waste (ion exchange resin in this embodiment) that cannot pass through the filter 28 remains inside the storage container 20. Since only the water inside the storage container 20 moves to the dehydration container 52, the slurry-like radioactive waste is dehydrated inside the storage container 20. The water that has moved into the dehydration container 52 is sent out to the second drainage path 66 via the filter 54 and moves to the storage tank 2.

[0045] In addition, in this embodiment, although the water that has moved into the dehydration container 52 in step S160 is returned to the storage tank 2, the configuration is not limited to this. For example, the water that has moved into the dehydration container 52 may not be returned to the storage tank 2 but may be discarded, or may be sent to another processing device (not shown) and discarded after being detoxified by the other processing device.

[0046] Next, it is determined whether the storage container 20 is full of radioactive waste (S170). In order to drain the water in the storage container 20 in step S160, the amount of the contents in the storage container 20 (that is, the radioactive waste) decreases by the amount of the drained water. If the storage container 20 is not full (NO in step S170), the process returns to step S110, and the processes of steps S110 to S170 are repeated until the storage container 20 is full. When 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 portion 44 is attached to the outer main body portion 42 (S190). Then, the process proceeds to the process of step S12 in FIG. 4.

[0047] As shown in FIG. 4, when the step S10 of storing radioactive waste is completed, a step of transferring the storage container 20 is executed (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 the storage facility. The outer container 40 has a shielding structure for shielding 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 taken out from the outer container 40. Then, only the inner container 22 is arranged in the storage facility. By arranging only the inner container 22 in the storage facility, a large number of inner containers 22 can be arranged in the storage facility. That is, a large amount of radioactive waste can be stored in the storage facility. Further, since the outer container 40 is not stored in the storage facility, it can be repeatedly used in the step S10 of storing radioactive waste and the step S12 of transferring the storage container. Therefore, the number of outer containers 40 can be reduced. Since the outer container 40 has a shielding structure, the manufacturing cost is high. By reducing the number of outer containers 40, the cost of the storage container 20 can be reduced. When the storage facility does not have a shielding structure, it may be arranged in the storage facility in a state where it is housed in the outer container 40 without taking out the inner container 22 from the outer container 40.

[0048] After the transfer step of the storage container 20 is completed, until the radioactive waste is subjected to harmless treatment (specifically, the heat treatment step described later), the radioactive waste is stored in the storage facility in a state of being housed in the inner container 22 (or the storage container 20). (S14).

[0049] When the storage period ends, the transfer process of the storage container 20 is executed (S16). In the transfer process of step S16, the storage container 20 is transferred from the storage facility to the heat treatment facility. In the transfer process of step S16, first, the inner container 22 arranged 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 (that is, the radioactive waste housed in the storage container 20) can be transferred outside the storage facility. Note that when the storage container 20 is arranged in the storage facility without taking out the inner container 22, the process of housing the inner container 22 in the outer container 40 is omitted. Then, the storage container 20 is transferred from the storage facility to the heat treatment facility.

[0050] Next, the radioactive waste removal process is executed (S18). The radioactive waste removal process is a process of removing the radioactive waste housed in the storage container 20 from the storage container 20.

[0051] The radioactive waste removal process is executed according to the following procedure. As shown in FIG. 6, first, the outer lid portion 44 is removed from the storage container 20 (S200). Next, a water supply path (not shown) and a slurry extraction 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 extraction path is connected to the connection portion 34.

[0052] Next, water is injected into the storage container 20 through the water supply path (S220). The dehydrated radioactive waste is housed in the storage container 20. For this reason, the radioactive waste in the storage container 20 is solidified and difficult to take out from the storage container 20 as it is. By injecting water into the storage container 20, the radioactive waste becomes slurry-like and is easier to take out from the storage container 20. Next, the slurry-like radioactive waste is taken out from the storage container 20 through the slurry extraction path (S230). Then, the process proceeds to step S20 in FIG. 4.

[0053] In addition, in the process of taking out the slurry-like radioactive waste from the storage container 20 in step S230 described above, the radioactive waste may be taken out from the storage container 20 by using the decompression device 56 of the storage device 10. Specifically, a 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 taken out from the storage container 20. Note that the slurry transfer container may be a tank provided in a heat treatment furnace described later. Next, a decompression path (not shown) is connected between the slurry transfer container and the decompression device 56, and a slurry extraction path (not shown) is connected between the slurry transfer container and the storage container 20 (specifically, the connection portion 34). Next, the decompression device 56 is operated to decompress the space inside the slurry transfer container. Next, the slurry-like radioactive waste inside the storage container 20 is transferred to the slurry transfer container through the slurry extraction path. By decompressing the space inside the slurry transfer container, a pressure difference is generated between the space inside the slurry transfer container and the space inside the storage container 20. Therefore, the slurry-like radioactive waste can be easily transferred from the storage container 20 to the slurry transfer container.

[0054] As shown in FIG. 4, when the process of taking out the radioactive waste is completed, a heat treatment process of the radioactive waste is executed (S20). Note that the heat treatment process only needs to be able to heat-treat the radioactive waste to make it harmless, and the specific method is not particularly limited. For example, the heat treatment process can be executed by a ball-type heat treatment furnace including a dry distillation section (for example, the heat treatment furnace disclosed in JP-A-2015-72132).

[0055] (Example 2) In the above Example 1, when dehydrating the slurry-like radioactive waste in the storage container 20, the water in the storage container 20 was returned to the dehydration container 52, but the configuration is not limited to this. For example, the water in the storage container 20 may not be returned to the dehydration container 52 but may be discharged to another container.

[0056] As shown in FIG. 7, the storage device 110 includes a storage container 20, a vacuum dehydration device 50, and a drainage container 58. Note that since the configurations of the storage container 20 and the vacuum dehydration device 50 are substantially the same as those of the storage container 20 and the vacuum dehydration device 50 in the above-described Example 1, detailed descriptions thereof are omitted.

[0057] The drainage container 58 receives the 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 the water in the storage container 20 via the first drainage path 160. Further, a second decompression path 170 is provided between the drainage container 58 and the decompression device 56. When the decompression device 56 is operated with the decompression device 56 connected to the second decompression path 170, the space in the drainage container 58 is decompressed via the second decompression path 170.

[0058] In this embodiment, a method for treating slurry-like radioactive waste will be described. In this embodiment, only the processes of steps S150 and S160 in the radioactive waste storage process of FIG. 5 are different from the method for treating slurry-like radioactive waste in the above-described Example 1, and for other steps, the same processes as those in the method for treating slurry-like radioactive waste in the above-described Example 1 are executed. Therefore, hereinafter, the processes of steps S150 and S160 will be described, and detailed descriptions of the processes of other steps are omitted.

[0059] In this embodiment, in step S150, instead of decompressing the space in the dehydration container 52, the space in the drainage container 58 is decompressed. Specifically, the decompression device 56 is operated with the decompression device 56 connected to the second decompression path 170. Then, the space in the drainage container 58 is decompressed via the second decompression path 170.

[0060] Next, in step S160, instead of the water in the storage container 20 moving to the dehydration container 52, the water in the storage container 20 moves 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. Thus, also in this embodiment, the slurry-like radioactive waste can be appropriately dehydrated in the storage container 20.

[0061] In addition, in the above-described first and second embodiments, the storage container 20 had a double structure including the inner container 22 and the outer container 40, but is not limited to such a configuration. The storage container may not 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 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 taken out. Further, since the storage container has a shielding structure, the storage container can be transferred to the outside of a facility having a shielding structure even if it does not have a double structure.

[0062] Points to note regarding the storage device 10 described in the embodiment will be described. The first drainage path 60 and the drain pipe 29 of the embodiment are an example of a "drainage device".

[0063] As described above, specific examples of the technology disclosed in this specification have been described in detail, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples exemplified above. Further, the technical elements described in this specification or the 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. Also, the technology exemplified in this specification or the drawings achieves a plurality of purposes simultaneously, and has technical utility by achieving one of those purposes itself.

Explanation of Reference Numerals

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

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; Equipped with The dehydration step includes: a first supplying step of supplying the slurry to a dewatering vessel; a first dehydration step of transferring water from the dehydration container to the outside; a second supplying step of supplying the slurry in the dehydration vessel to the storage vessel; A second dehydration step of further dehydrating the slurry supplied to the storage container in the second supply step in the storage container; A method for treating radioactive waste comprising the steps of:

2. 2. The method for treating radioactive waste according to claim 1, 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.

3. 3. The method for treating radioactive waste according to claim 2, wherein in the second dehydration step, the pressure in the dehydration container is reduced relative to the storage container to move water in the storage container to the dehydration container.

4. 3. The method for treating radioactive waste according to claim 2, wherein in the second dehydration step, a drainage container is depressurized relative to the storage container to move water in the storage container to the drainage container.

5. 2. The method for treating radioactive waste according to claim 1, further comprising a transport step of transporting 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.

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

7. 7. The radioactive waste treatment method according to claim 6, wherein in the transferring step, a slurry transfer container is depressurized relative to the storage container to transfer the slurry in the storage container to the slurry transfer container.

8. A storage device for dehydrating and storing a slurry containing radioactive waste using the radioactive waste treatment method according to any one of claims 1 to 7, A storage container for dehydrating and storing the slurry; A decompression device that reduces the pressure in the storage container so as to move the slurry into the storage container; a filter disposed within the storage container, the filter allowing water to pass but preventing the radioactive waste from passing therethrough; a drainage device that drains water from the storage container to the outside through the filter, The storage container comprises: an inner container for containing the radioactive waste; and 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; Equipped with The inner container has the filter disposed therein.

9. The storage device according to claim 8 , wherein the outer container is configured to accommodate a plurality of the inner containers.

10. The storage device according to claim 8 , wherein the outer container has a shielding structure for shielding against radiation.

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