Radioactive waste treatment systems and methods

Abstract

To provide a system and a method for processing a radioactive waste for efficiently removing water from a radioactive waste and increasing the filling rate and also improving the safety of operations.SOLUTION: The present invention includes: a processing container arranged below a slurry tank for storing a slurry of radioactive waste and having a first pipe connection coupler in an entrance part of the upper part to store a radioactive waste; and a shielding member provided between the slurry tank and the processing container and having the pipe connection opening unit.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a radioactive waste processing system and method. Background Art

[0002] In a nuclear power plant, when core fuel disposed inside a reactor pressure vessel melts, structures inside the reactor containment vessel also melt and solidify, forming debris as radioactive waste. Therefore, it is necessary to recover and process radioactive waste such as debris from the reactor containment vessel. In this case, the recovered radioactive waste includes those in a slurry state. As a technique for transporting slurry, for example, there is one described in Patent Document 1. Prior Art Documents Patent Documents

[0003] Patent Document 1 Japanese Unexamined Patent Publication No. Hei 2-175344 Summary of the Invention Problem to be Solved by the Invention

[0004] Radioactive waste present inside a reactor pressure vessel is submerged in water, so the recovered radioactive waste includes those in a slurry state. Since radioactive waste is stored in containers for transportation and storage, it is necessary to remove as much moisture as possible from the radioactive waste to increase the filling rate. Furthermore, since radioactive waste in a slurry state contains radioactive materials, it is necessary to safely transport the radioactive waste.

[0005] The present disclosure solves the above-described problems, and aims to provide a radioactive waste processing system and method that efficiently removes moisture from radioactive waste to improve the filling rate and also improve work safety. Means for Solving the Problem

[0006] A radioactive waste treatment system of the present disclosure for achieving the above objectives comprises a treatment container disposed below a slurry tank for storing slurry-like radioactive waste and having a first pipe connection coupler at its upper inlet, and capable of containing the radioactive waste, and a shielding member provided between the slurry tank and the treatment container and having a pipe connection opening.

[0007] Furthermore, the radioactive waste treatment method of this disclosure includes the steps of: filling a transport container located below the slurry tank with slurry-like radioactive waste stored in a slurry tank; transporting the transport container filled with the radioactive waste and placing it above a treatment container via a shielding member; connecting a first piping coupler provided at the upper inlet of the treatment container with a second piping coupler provided at the lower outlet of the transport container; and filling the treatment container with the radioactive waste filled in the transport container.

[0008] Furthermore, the radioactive waste treatment method of this disclosure includes the steps of: placing a treatment container below a slurry tank for storing radioactive waste via a shielding member; connecting a first piping coupler provided at the upper inlet of the treatment container to a second piping coupler provided at the lower outlet of the slurry tank; and filling the treatment container with the radioactive waste stored in the slurry tank. [Effects of the Invention]

[0009] According to the radioactive waste treatment system and method of this disclosure, it is possible to efficiently remove moisture from radioactive waste and improve the filling rate, as well as improve the safety of the work. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is a schematic diagram representing the radioactive waste treatment system of the first embodiment. [Figure 2]Figure 2 is a flowchart illustrating the radioactive waste processing method according to the first embodiment. [Figure 3] Figure 3 is a schematic diagram illustrating the process of filling the transport container with radioactive waste. [Figure 4] Figure 4 is a schematic diagram illustrating the pipe connection process. [Figure 5] Figure 5 is a schematic diagram illustrating a modified example of pipe connection work. [Figure 6] Figure 6 is a schematic diagram showing the radioactive waste processing system of the second embodiment. [Figure 7] Figure 7 is a flowchart illustrating the radioactive waste processing method of the second embodiment. [Modes for carrying out the invention]

[0011] Preferred embodiments of the present disclosure will be described in detail below with reference to the drawings. However, these embodiments do not limit the present disclosure, and where there are multiple embodiments, they may be combinations of these embodiments. Furthermore, the components in the embodiments include those readily conceivable by those skilled in the art, those that are substantially identical, and those that are equivalent.

[0012] [First Embodiment] <Radioactive waste processing system> Figure 1 is a schematic diagram representing the radioactive waste treatment system of the first embodiment.

[0013] In a nuclear power plant, when the reactor core and other components inside the reactor vessel melt, molten material such as molten fuel is generated, and this solidified molten material (debris) is subject to recovery as radioactive waste. The radioactive waste processing system and method of this embodiment, for example, recovers and stores radioactive waste generated at a nuclear power plant and fills it into a processing container. After being stored in the processing container, the radioactive waste is dried and stored. However, the radioactive waste is not limited to debris, but may also include spent fuel or structures generated during decommissioning.

[0014] As shown in Figure 1, the radioactive waste treatment system 10 comprises a treatment container 11, a transfer container (slurry tank) 12, and a shielding member 13. In the first embodiment, the transfer container 12 is described in relation to a slurry tank for storing slurry-like radioactive waste.

[0015] The processing container 11 comprises a container body 21 and a lid 22. The container body 21 is cylindrical in shape, with an open top and a closed bottom. The container body 21 has an internal space 23 capable of containing radioactive waste. The lid 22 is disc-shaped and can open and close the top opening of the container body 21. The lid 22 is detachably attached to the top of the container body 21 by bolts. However, the processing container 11 is not limited to this shape.

[0016] The processing container 11 has an inlet 24 that penetrates the center of the lid 22 in the direction of the plate thickness. The processing container 11 also has a first pipe connection coupler (socket) 25 attached to the outside of the inlet 24 at the top of the lid 22. The first pipe connection coupler 25, although not shown, has a valve inside, and the valve is biased and supported in a direction that closes the passage by the biasing force of a spring. When another coupler (plug part) is connected to the first pipe connection coupler 25, the valve moves against the biasing force of the spring and opens the passage.

[0017] The transfer container 12 stores slurry-shaped radioactive waste 100. The slurry-shaped radioactive waste 100 is a mixture of sludge 101 as solid matter and moisture 102. The transfer container 12 is arranged above the processing container 11. The transfer container 12 is provided with an upper opening 31 at an upper portion thereof, and a discharge pipe 32 is connected to a lower opening at a lower portion thereof. The discharge pipe 32 is provided with an opening / closing valve 33 at an intermediate portion thereof, and a second pipe connection coupler 34 is attached to a lower end portion thereof. Although not shown in the figure, the second pipe connection coupler 34 is provided with a valve inside, and the valve is biased and supported in a direction to close a passage by a biasing force of a spring. When another coupler is connected to the second pipe connection coupler 34, the valve moves against the biasing force of the spring to open the passage. Further, the transfer container 12 is provided with a visual confirmation window 35 through which the inside can be visually checked. The visual confirmation window 35 is formed of, for example, a transparent member.

[0018] The shielding member 13 is arranged between the processing container 11 and the transfer container 12. The shielding member is arranged along the horizontal direction between the processing container 11 and the transfer container 12. The shielding member 13 is formed of concrete having a predetermined thickness with a neutron shielding function, but may be formed of carbon steel, stainless steel or the like, or may use a resin containing boron or a boron compound. The shielding member 13 is provided with a pipe connection opening 41 penetrating in the plate thickness direction.

[0019] The processing container 11 is arranged on a floor surface 51. The shielding member 13 is supported on the floor surface 51 via a support member (not shown). Further, the shielding member 13 is provided at an upper portion thereof with a support portion 53 that supports the transfer container 12 by a support member 52. The transfer container 12 is movable upward relative to the support portion 53, and is transferred by a transfer device such as a crane (not shown).

[0020] With respect to the shielding member 13, the processing container 11 is positioned on the lower floor surface 51, and the transfer container 12 is supported by the upper support part 53. In this state, the first pipe connection coupler 25 of the processing container 11 and the second pipe connection coupler 34 of the transfer container 12 face each other vertically through the pipe connection opening 41. The first pipe connection coupler 25 and the second pipe connection coupler 34 can be connected by either the second pipe connection coupler 34 descending relative to the first pipe connection coupler 25, or the first pipe connection coupler 25 rising relative to the second pipe connection coupler 34.

[0021] <Methods for disposing of radioactive waste> Figure 2 is a flowchart showing the radioactive waste processing method of the first embodiment, Figure 3 is a schematic diagram showing the filling of radioactive waste into the transport container, Figure 4 is a schematic diagram showing the piping connection work, and Figure 5 is a schematic diagram showing a modified example of the piping connection work.

[0022] The first embodiment of the radioactive waste treatment method is a method of treating radioactive waste using the radioactive waste treatment system 10 described above, wherein the slurry-like radioactive waste 100 is placed in a treatment container 11 via a transfer container 12, and then dried and stored. Furthermore, in the first embodiment of the radioactive waste treatment method, various treatments are performed remotely by an operator using a manipulator (not shown).

[0023] As shown in Figure 2, in step S11, the transfer container 12 is positioned in a predetermined location. That is, as shown in Figure 3, the slurry tank 61 is supported by an upper support base 56. The slurry tank 61 stores slurry-like radioactive waste composed of sludge 101 and water 102. A discharge pipe 62 is connected to the lower outlet of the slurry tank 61, and an on-off valve 63 is provided on the discharge pipe 62. The transfer container 12 is positioned below the slurry tank 61 by being supported by a lower support base 57. At this time, the on-off valve 33 and the second pipe connection coupler 34 of the transfer container 12 are closed. The slurry tank 61 is also provided with a viewing window 65 that allows the interior to be seen. The viewing window 65 is formed, for example, by a transparent material.

[0024] As shown in Figures 2 and 3, in step S12, the transport container 12 is filled with slurry-like radioactive waste 100. That is, the shut-off valve 63 is opened, and the radioactive waste 100 stored in the slurry tank 61 is discharged through the discharge pipe 62. The radioactive waste 100 is filled into the transport container 12 from the upper opening 31. Once a predetermined amount of radioactive waste 100 has been filled into the transport container 12, the shut-off valve 63 is closed.

[0025] In step S13, the transport container 12 filled with radioactive waste 100 is transported to a predetermined position and placed. That is, as shown in Figure 1, the transport container 12 is transported and placed on the support portion 53 above the shielding member 13. Then, in step S14, the transport container 12 and the processing container 11 located below the transport container 12 are connected by piping. That is, the first piping connection coupler 25 of the processing container 11 located below and the second piping connection coupler 34 of the transport container 12 located above are connected to the shielding member 13.

[0026] In this case, as shown in Figure 4, the discharge pipe 32 is made expandable and contractible in the axial direction (up and down), and the second pipe connection coupler 34 of the transfer container 12 is lowered relative to the first pipe connection coupler 25 of the processing container 11. Then, the first pipe connection coupler 25 and the second pipe connection coupler 34 are connected. In this case, the discharge pipe 32 can be configured in a bellows shape, and an operator can use a manipulator to connect the second pipe connection coupler 34 to the first pipe connection coupler 25.

[0027] Furthermore, as shown in Figure 5, a lifting device 54 is installed on the floor surface 51, and the processing container 11 is placed on the lifting device 54. Then, by raising the processing container 11 with the lifting device 54, the first pipe connection coupler 25 of the processing container 11 is raised to connect with the second pipe connection coupler 34 of the transfer container 12. Then, the first pipe connection coupler 25 and the second pipe connection coupler 34 are connected.

[0028] As shown in Figures 2, 4, and 5, in step S15, the filling of the processing container 11 with radioactive waste 100 begins. The processing container 11 and the transfer container 12 are connected by the first pipe connection coupler 25 and the second pipe connection coupler 34, opening the flow path and creating internal communication. Therefore, by opening the on-off valve 33, the radioactive waste 100 from the transfer container 12 is filled into the space 23 of the processing container 11 through the discharge pipe 32.

[0029] At this time, in the radioactive waste 100 in the transfer container 12, the sludge 101 settles and the water 102 floats due to specific gravity separation. When filling the radioactive waste 100 in the transfer container 12 into the processing container 11, it is necessary to fill the processing container 11 with as little water 102 as possible, containing only the sludge 101. The worker monitors the inside of the transfer container 12 through the viewing window 35, and closes the on / off valve 33 when most of the sludge 101 has filled the processing container 11.

[0030] Once the transfer of radioactive waste 100 (sludge 101) from the transfer container 12 to the processing container 11 is complete, the connection between the first piping coupler 25 and the second piping coupler 34 is released. Then, in step S16, the radioactive waste 100 is dried. The drying of the radioactive waste 100 is carried out, for example, by supplying a drying gas to the inside of the processing container 11. However, the drying of the radioactive waste 100 is not limited to this method, and may also be carried out, for example, by heating the outside of the processing container 11 with a heater or by depressurizing the inside of the processing container 11 with a vacuum pump. Once the drying of the radioactive waste 100 is completed, in step S17, the radioactive waste 100 is stored in the processing container 11.

[0031] [Second Embodiment] <Radioactive waste processing system> Figure 6 is a schematic diagram showing the radioactive waste processing system of the second embodiment. Components having the same functions as those in the first embodiment described above are denoted by the same reference numerals, and detailed descriptions are omitted.

[0032] As shown in Figure 6, the radioactive waste processing system 10A comprises a processing container 11, a slurry tank 61, and a shielding member 13. The processing container 11 and the shielding member 13 are the same as in the first embodiment. In the second embodiment, the transfer container 12 (see Figure 1) is eliminated, and the radioactive waste 100 stored in the slurry tank 61 is directly filled into the processing container 11.

[0033] The processing container 11 has a container body 21 and a lid 22. A first piping connection coupler 25 is attached to the outside of the inlet 24 of the lid 22 of the processing container 11.

[0034] The slurry tank 61 stores the slurry-like radioactive waste 100. The slurry-like radioactive waste 100 is a mixture of solid sludge 101 and water 102. The slurry tank 61 is positioned above the processing container 11. A discharge pipe 62 is connected to the lower opening of the slurry tank 61. The discharge pipe 62 has an on / off valve 63 in the middle and a second pipe connection coupler 64 attached to its lower end. The slurry tank 61 is also provided with a viewing window 65 that allows the interior to be seen. The viewing window 65 is formed, for example, from a transparent material.

[0035] The shielding member 13 is positioned between the processing container 11 and the slurry tank 61. The shielding member is positioned horizontally between the processing container 11 and the slurry tank 61. The shielding member 13 is provided with a pipe connection opening 41 that penetrates in the thickness direction.

[0036] With respect to the shielding member 13, the processing container 11 is positioned on the lower floor surface 51, and the slurry tank 61 is supported by the upper support part 53. In this state, the first pipe connection coupler 25 of the processing container 11 and the second pipe connection coupler 64 of the slurry tank 61 face each other vertically through the pipe connection opening 41. The first pipe connection coupler 25 and the second pipe connection coupler 64 can be connected by either the second pipe connection coupler 64 descending relative to the first pipe connection coupler 25, or the first pipe connection coupler 25 rising relative to the second pipe connection coupler 64.

[0037] <Methods for disposing of radioactive waste> Figure 7 is a flowchart illustrating the radioactive waste processing method of the second embodiment.

[0038] The second embodiment of the radioactive waste treatment method is a method of treating radioactive waste using the radioactive waste treatment system 10A described above, wherein the slurry-like radioactive waste 100 is placed in a treatment container 11, dried, and then stored. Furthermore, in the second embodiment of the radioactive waste treatment method, various treatments are performed remotely by an operator using a manipulator (not shown).

[0039] As shown in Figures 6 and 7, in step S21, the processing container 11 is positioned in a predetermined location. That is, the slurry tank 61 is supported by the support part 53 above the shielding member 13. The slurry tank 61 stores slurry-like radioactive waste composed of sludge 101 and water 102. The slurry tank 61 is equipped with an on-off valve 63 and a second pipe connection coupler 64 on the discharge pipe 62. At this time, the on-off valve 63 and the second pipe connection coupler 64 of the slurry tank 61 are closed. The processing container 11 is positioned below the shielding member 13 on the floor surface 51. The slurry tank 61 is equipped with a viewing window 65 that allows the interior to be viewed.

[0040] In step S22, the slurry tank 61 and the processing container 11 located below the slurry tank 61 are connected by piping. Specifically, the first piping coupler 25 of the processing container 11 located below and the second piping coupler 64 of the slurry tank 61 located above are connected to the shielding member 13. In this case, similar to the first embodiment, the discharge piping 62 is made extendable and retractable in the axial direction (up and down direction), and the second piping coupler 64 of the slurry tank 61 is lowered to connect it to the first piping coupler 25 of the processing container 11. Alternatively, the processing container 11 is raised by a lifting device to connect the first piping coupler 25 of the processing container 11 to the second piping coupler 64 of the slurry tank 61.

[0041] In step S23, the filling of radioactive waste 100 into the processing container 11 begins. The processing container 11 and the slurry tank 61 are connected by opening the flow path and creating internal communication between them through the connection of the first piping coupler 25 and the second piping coupler 64. Therefore, by opening the on / off valve 63, the radioactive waste 100 in the slurry tank 61, which has been left to stand for a certain period of time, is filled into the space 23 of the processing container 11 through the discharge pipe 62.

[0042] At this time, in the slurry tank 61, the radioactive waste 100 has undergone gravity separation, with the sludge 101 settling and the water 102 floating to the surface. When filling the processing container 11 with the radioactive waste 100 from the slurry tank 61, it is necessary to fill the processing container 11 with only the sludge 101, with as little water 102 as possible. The worker monitors the inside of the slurry tank 61 through the viewing window 65, and closes the on / off valve 63 when most of the sludge 101 has been filled into the processing container 11.

[0043] Once the transfer of radioactive waste 100 (sludge 101) from slurry tank 61 to processing container 11 is complete, the connection between the first piping coupler 25 and the second piping coupler 64 is released. Then, in step S24, the radioactive waste 100 is dried. The drying of the radioactive waste 100 is carried out, for example, by supplying a drying gas to the inside of the processing container 11. However, the drying of the radioactive waste 100 is not limited to this method, and may also be carried out, for example, by heating the outside of the processing container 11 with a heater or by depressurizing the inside of the processing container 11 with a vacuum pump. Once the drying of the radioactive waste 100 is completed, in step S25, the radioactive waste 100 is stored in the processing container 11.

[0044] [Effects of this embodiment] The radioactive waste treatment system according to the first embodiment comprises a treatment container 11 that is positioned below a transfer container 12 or slurry tank 61 that stores slurry-like radioactive waste 100 and is equipped with a first piping connection coupler 25 at its upper inlet and capable of accommodating radioactive waste 100, and a shielding member 13 that is provided between the transfer container 12 or slurry tank 61 and the treatment container 11 and is equipped with a piping connection opening 41.

[0045] According to the radioactive waste processing system of the first embodiment, the slurry-like radioactive waste 100 stored in the slurry tank 61 is lowered and filled into the processing container 11 located below. This allows the radioactive waste 100, whose moisture content has been reduced by specific gravity separation, to be contained in the processing container 11, and moisture can be efficiently removed from the radioactive waste 100 to improve the filling rate. Furthermore, by providing a shielding member 13 between the transfer container 12 or slurry tank 61 and the processing container 11, the safety of the transfer operation of the radioactive waste 100 can be improved.

[0046] The radioactive waste treatment system according to the second embodiment is the radioactive waste treatment system according to the first embodiment, further comprising second piping couplers 34, 64 provided at the lower outlet of the transfer container 12 or slurry tank 61, and the second piping couplers 34, 64 can descend through the piping connection opening 41 and be connected to the first piping coupler 25. This allows for easy piping connection between the transfer container 12 or slurry tank 61 and the treatment container 11.

[0047] The radioactive waste treatment system according to the third embodiment is the radioactive waste treatment system according to the first embodiment, further comprising a first piping coupler 25 that can rise through a piping opening 41 and connect to second piping couplers 34, 64 provided at the lower outlet of the transfer container 12 or slurry tank 61. This allows for easy piping connection between the transfer container 12 or slurry tank 61 and the treatment container 11.

[0048] The radioactive waste treatment system according to the fourth embodiment is a radioactive waste treatment system according to any one of the first to third embodiments, further comprising a slurry tank which is a transfer container 12 and is placed above the treatment container 11 with radioactive waste 100 filled inside at a predetermined position. This allows the placement position of the treatment container 11 to be appropriately set relative to the slurry tank 61.

[0049] The radioactive waste treatment system according to the fifth embodiment is the radioactive waste treatment system according to the fourth embodiment, further comprising a viewing window 35 in the transfer container 12 that allows the inside to be viewed. This makes it possible to visually check the filling state of the radioactive waste 100 in the treatment container 11, and to fill only the settled material (mainly sludge 101) of the radioactive waste 100 into the treatment container 11.

[0050] The sixth embodiment of the radioactive waste processing method includes the steps of: filling a transfer container 12 located below the slurry tank 61 with slurry-like radioactive waste 100 stored in a slurry tank 61; transporting the transfer container 12 filled with radioactive waste 100 and placing it above the processing container 11 via a shielding member 13; connecting a first piping coupler 25 provided at the upper inlet of the processing container 11 with a second piping coupler 34 provided at the lower outlet of the transfer container 12; and filling the processing container 11 with the radioactive waste 100 filled in the transfer container 12. This makes it possible to efficiently contain the radioactive waste 100, whose moisture content has been reduced by specific gravity separation, into the processing container 11, thereby improving the filling rate, and also improves the safety of the transport operation of the radioactive waste 100 with the shielding member 13.

[0051] The seventh embodiment of the radioactive waste processing method includes the steps of: placing a processing container 11 below a slurry tank 61 storing radioactive waste 100 via a shielding member 13; connecting a first piping coupler 25 provided at the upper inlet of the processing container 11 to a second piping coupler 64 provided at the lower outlet of the slurry tank 61; and filling the processing container 11 with the radioactive waste 100 stored in the slurry tank 61. This allows for efficient storage of the radioactive waste 100, whose moisture content has been reduced by specific gravity separation, into the processing container 11, thereby improving the filling rate, and also improves the safety of the transport operation of the radioactive waste 100 with the shielding member 13. [Explanation of Symbols]

[0052] 10,10A Radioactive waste processing system 11 Processing container 12. Transfer container (slurry tank) 13 Shielding member 21 Container body 22 Lid 23 Space section 24 Entrance 25. Coupler for connecting the first pipe 31 Upper opening 32 Discharge piping 33. Shut-off valve 34. Coupler for connecting the second pipe. 35 Viewing window 41. Opening for pipe connection 54 Lifting device 61 Slurry Tank 62 Discharge piping 63 Shut-off valve 64. Coupler for connecting the second pipe. 100 Radioactive waste 101 Sludge 102 Moisture

Claims

1. A processing container capable of containing the radioactive waste is positioned below a slurry tank for storing slurry-like radioactive waste, and a first piping connection coupler is provided at the upper inlet, A shielding member provided between the slurry tank and the processing container, and having an opening for pipe connection, Equipped with, The first pipe connection coupler can rise through the pipe connection opening and connect to a second pipe connection coupler provided at the lower outlet of the slurry tank. A system for processing radioactive waste.

2. A processing container capable of containing the radioactive waste is positioned below a slurry tank for storing slurry-like radioactive waste, and a first piping connection coupler is provided at the upper inlet, A shielding member provided between the slurry tank and the processing container, and having an opening for pipe connection, Equipped with, The slurry tank is a transfer container and is positioned above the processing container with the radioactive waste filled inside at a predetermined location. A system for processing radioactive waste.

3. The transport container is provided with a viewing window that allows the interior to be seen. The radioactive waste treatment system according to claim 2.

4. The steps include: filling a transport container located below the slurry tank with the slurry-like radioactive waste stored in the slurry tank; The steps include transporting the transport container filled with the radioactive waste and placing it above the processing container via a shielding member, The steps include connecting a first pipe connection coupler provided at the upper inlet of the processing container and a second pipe connection coupler provided at the lower outlet of the transfer container, The steps include: filling the radioactive waste, which has been filled in the transport container, into the processing container; A method for processing radioactive waste containing [unclear / unclear].

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