Container dismantling device

Abstract

To provide a container dismantling device which improves workability of container dismantling work.SOLUTION: A container dismantling device for dismantling a container contaminated with radioactive substances is provided, the device comprising a base supported at the bottom inside the container, a support member disposed along a vertical direction and supported by the base at a bottom thereof, and a cutting device supported by the support member in such a way that the cutting device is movable along the vertical direction and movable in the circumferential direction.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present disclosure relates to a container dismantling device for dismantling containers contaminated with radioactive materials. [Background technology]

[0002] In a nuclear power plant, a reactor containment vessel is erected on solid ground such as bedrock, and a nuclear reactor is placed inside it. The reactor is constructed by placing reactor internals such as fuel inside the reactor vessel. When a nuclear reactor is to be disposed of, the reactor internals are removed from inside the reactor vessel, and then the reactor vessel is cut and dismantled. Techniques for dismantling a reactor vessel are described, for example, in Patent Documents 1 and 2. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 61-67000 [Patent Document 2] Special Publication No. 7-66079 Summary of the Invention [Problem to be solved by the invention]

[0004] When dismantling a reactor vessel, a dismantling device is suspended and supported by a crane, and the dismantling device is moved to cut the reactor vessel. In this case, not only is the dismantling device suspended and supported by a crane, but the cut pieces generated by cutting the reactor vessel also need to be carried away by the crane. Therefore, after moving the dismantling device to cut the reactor vessel, the crane needs to support the cut pieces and move them to a predetermined position, which poses a problem of requiring a long time for the dismantling work.

[0005] The present disclosure is intended to solve the above-mentioned problems, and aims to provide a container dismantling device that improves the workability of container dismantling work. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the container dismantling device of the present disclosure is a container dismantling device for dismantling containers contaminated with radioactive materials, and comprises a stand supported at the bottom inside the container, a support member arranged along the vertical direction and whose bottom is supported by the stand, and a cutting device supported on the support member so as to be movable along the vertical direction and movable circumferentially. [Effects of the Invention]

[0007] According to the container dismantling device of the present disclosure, the workability of the container dismantling work can be improved. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a longitudinal cross-sectional view showing a pressurized water reactor. [Figure 2] FIG. 2 is a schematic front view showing the container dismantling device of this embodiment. [Figure 3] FIG. 3 is a schematic plan view showing the container dismantling device. [Figure 4] FIG. 4 is a schematic diagram showing a container dismantling operation performed by the container dismantling device. [Figure 5] FIG. 5 is a schematic diagram showing a container dismantling operation performed by the container dismantling device. DETAILED DESCRIPTION OF THE INVENTION

[0009] Preferred embodiments of the present disclosure will be described in detail below with reference to the drawings. Note that the present disclosure is not limited to these embodiments, and when there are multiple embodiments, the present disclosure also includes configurations that combine the embodiments. Furthermore, the components in the embodiments include those that can be easily imagined by a person skilled in the art, those that are substantially identical, and those that are within the so-called equivalent range.

[0010] <Pressurized water reactor> FIG. 1 is a longitudinal cross-sectional view showing a pressurized water reactor.

[0011] Although not shown, the nuclear power plant has a nuclear reactor and a steam generator arranged in a reactor containment vessel, and a steam turbine power generation facility. The nuclear reactor in this embodiment is a pressurized water reactor (PWR). However, the nuclear reactor may be any type of nuclear reactor, such as a boiling water reactor (BWR) or a fast breeder reactor (FBR).

[0012] As shown in FIG. 1, in a pressurized water reactor 10, a reactor vessel 11 is composed of a reactor vessel main body 12 and a reactor vessel lid 13 attached to the top so that reactor internals can be inserted inside, and the reactor vessel lid 13 is fixed to the reactor vessel main body 12 by a plurality of stud bolts 14 and nuts 15 so that it can be opened and closed.

[0013] The reactor vessel body 12 has a cylindrical shape that is open at the top and closed at the bottom, forming a hemispherical shape, and is provided with an inlet nozzle 16 at the top for supplying light water as primary coolant and an outlet nozzle 17 for discharging the light water. A core barrel 18 is disposed inside the reactor vessel body 12, and its upper part is supported by the inner wall surface of the reactor vessel body 12. An upper core support plate 19 is disposed inside the reactor vessel body 12, and its upper part is supported by the upper part of the core barrel 18. An upper core plate 20 is suspended and supported from the upper core support plate 19 by a plurality of core support rods 21.

[0014] A lower core support plate 22 is supported below the core barrel 18, and the outer periphery of the lower core support plate 22 is positioned and supported by positioning members 23 on the inner wall surface of the reactor vessel body 12. A lower core plate 24 is supported below the core barrel 18. A core 25 is formed by arranging a large number of fuel assemblies 26, and a large number of control rods 27 are arranged inside, and the control rods 27 are insertable into the fuel assemblies 26. A large number of control rod cluster guide tubes 28 are fixed to the upper core support plate 19, and the control rods 27 can be inserted therein. The reactor vessel lid 13 is hemispherical, and a control rod drive mechanism 29 is arranged therein. A plurality of control rod cluster drive shafts 30 are inserted into the control rod cluster guide tubes 28, and the control rods 27 are connected to the lower ends thereof. The control rod drive mechanism 29 controls the reactor power by inserting and withdrawing each control rod 27 into and from the core 25.

[0015] Furthermore, a detector guide device 31 is disposed inside the reactor vessel 11. The detector guide device 31 guides a neutron flux detector (not shown) from an instrumentation nozzle 32 on the reactor vessel lid 13 to the core 25 (fuel assemblies 26) through a guide member 33. The neutron flux detector can measure the neutron level and distribution (neutron flux). Specifically, the detector guide device 31 guides the neutron flux detector (not shown) from the instrumentation nozzle 32 on the reactor vessel lid 13 to the core 25 (fuel assemblies 26) through the guide member 33 and a guide thimble (not shown) fixed to the lower end of the guide member 33.

[0016] <Container dismantling equipment> FIG. 2 is a schematic front view showing the container dismantling device of this embodiment, and FIG. 3 is a schematic plan view showing the container dismantling device.

[0017] 2 and 3, the vessel dismantling device 50 dismantles a reactor vessel main body 12 (reactor vessel 11) contaminated with radioactive materials in a decommissioned pressurized water reactor 10. Here, the reactor vessel main body 12 is in a state where reactor internal structures such as the reactor vessel lid 13 and the reactor core 25 have already been removed. The reactor vessel main body 12 is operated by remote control by a worker outside the reactor containment vessel (not shown).

[0018] The container dismantling device 50 includes a stand 51, a beam (support member) 52, and a cutting device 53.

[0019] The pedestal 51 is supported at the lower part inside the reactor vessel main body 12. The pedestal 51 has a disk shape, and its outer periphery is supported horizontally on the inner circumferential wall of the reactor vessel main body 12. That is, the reactor vessel main body 12 is in a state where the reactor internals have been removed, but positioning members 23 are attached to the inner circumferential wall. A plurality of positioning members 23 are provided at intervals in the circumferential direction and position and support the lower core support plate 22 (see FIG. 1 ) that has already been removed. The pedestal 51 has its outer periphery supported horizontally by the plurality of positioning members 23. However, the pedestal 51 is not limited to a disk shape. Furthermore, the pedestal 51 is not limited to a configuration in which it is supported by the positioning members 23, and may be supported, for example, by a plurality of in-core instrumentation guide tubes that penetrate the bottom head of the reactor vessel main body 12.

[0020] The beam 52 is arranged vertically inside the reactor vessel body 12. The beam 52 has a cylindrical shape, and its lower part is supported by the pedestal 51. However, the shape of the beam 52 is not limited to a cylindrical shape. The beam 52 is arranged at the center position of the reactor vessel body 12.

[0021] The cutting device 53 is supported on the beam 52 so as to be movable in the vertical direction and also in the circumferential direction. The cutting device 53 is preferably, for example, a gas cutting device, but is not limited to a gas cutting device and may be, for example, a laser cutting device.

[0022] The beam 52 supports the movable body 61 so that it can move freely in the vertical direction and also in the circumferential direction. The movable body 61 can be moved in the vertical direction and also in the circumferential direction by a drive device 62. The drive device 62 has, for example, a drive motor and a rack-and-pinion mechanism, and can move the movable body 61 in the vertical direction relative to the beam 52. The drive device 62 also has, for example, a drive motor and a planetary gear mechanism, and can move the movable body 61 in the circumferential direction relative to the beam 52. Note that the drive device 62 is not limited to a rack-and-pinion mechanism or a planetary gear mechanism, and an existing mechanism may be used as appropriate.

[0023] A support arm 63 extends radially outward from the outer periphery of the movable body 61. The support arm 63 is arranged along the radial direction of the reactor vessel body 12, one end of which is connected to the movable body 61, and the cutting device 53 is attached to the other end of the support arm 63.

[0024] Therefore, when the driving device 62 moves the movable body 61 in the vertical direction along the beam 52, the cutting device 53 supported by the movable body 61 via the support arm 63 can be moved in the vertical direction with a predetermined gap between them on the inner peripheral wall surface of the reactor vessel body 12. In addition, when the driving device 62 moves the movable body 61 in the circumferential direction relative to the beam 52, the cutting device 53 supported by the movable body 61 via the support arm 63 can be moved in the circumferential direction with a predetermined gap between them on the inner peripheral wall surface of the reactor vessel body 12.

[0025] The cutting device 53 may be movable along the radial direction of the reactor vessel body 12 relative to the beam 52 or the moving body 61. For example, a telescopic mechanism may be provided on the support arm 63, and the telescopic mechanism may be operated by a drive cylinder.

[0026] The vessel dismantling device 50 is equipped with a drainage device 71. The drainage device 71 has a nozzle 72, piping 73, and a pump 74. The nozzle 72 is arranged inside the reactor vessel body 12. The nozzle 72 is attached to one end of the piping 73, and the other end is drawn out to the outside of the reactor vessel body 12 and has the pump 74 attached to it. By driving the pump 74, the nozzle 72 can suck in water stored in the reactor vessel body 12 via the piping 73 and discharge it to the outside through the piping 73.

[0027] The vessel dismantling device 50 is equipped with a protective sheet 81. The protective sheet 81 is a fireproof sheet and is provided on the support arm 63 (or the cutting device 53). The protective sheet 81 suppresses the diffusion of chips from the reactor vessel body 12 cut by the cutting device 53. The protective sheet 81 has an attachment portion 82 that is arranged on the inside of the reactor vessel body 12 along the vertical direction, a covering portion 83 that is arranged on the outside of the reactor vessel body 12 along the vertical direction, and a connecting portion 84 that connects the attachment portion 82 and the covering portion 83. The attachment portion 82 of the protective sheet 81 is supported by the support arm 63. However, it is preferable that the protective sheet 81 be provided so as to be freely movable with respect to the support arm 63.

[0028] <Container disassembly method> FIG. 4 is a schematic diagram showing a container dismantling operation performed by the container dismantling device.

[0029] 2 and 3, the reactor vessel lid 13 is removed from the reactor vessel main body 12, and reactor internal structures such as the reactor core 25 are carried out from inside. However, water (cooling water) remains. The lower part of the reactor vessel main body 12 is supported by a support base 91.

[0030] The vessel dismantling device 50, which is assembled with the cradle 51, beam 52, and cutting device 53, is carried into the reactor vessel body 12 by the crane device 92. At this time, the cradle 51 of the vessel dismantling device 50 is supported by the positioning member 23 of the reactor vessel body 12. Then, the driving device 62 moves the movable body 61 vertically relative to the beam 52, and the cutting device 53 is positioned facing the inner peripheral wall surface of the reactor vessel body 12. Then, the driving device 62 moves the movable body 61 circumferentially relative to the beam 52, and moves the cutting device 53 circumferentially, thereby starting cutting of the reactor vessel body 12. At this time, the protective sheet 81 can suppress the diffusion of chips cut by the cutting device 53.

[0031] 4, when the cutting device 53 moves 360 degrees in the circumferential direction, the reactor vessel body 12 is cut in the circumferential direction, and ring-shaped cut pieces 12a are formed. While the cutting device 53 is cutting the reactor vessel body 12, or just before the cutting device 53 finishes cutting the reactor vessel body 12, the crane device 92 is operated to hold the cut pieces 12a that are cut off from the reactor vessel body 12. It is preferable that the crane device 92 hold the cut pieces 12a at multiple locations. By operating the crane device 92, the cut pieces 12a are transported to a predetermined storage position. At this time, the protective sheet 81 covering the cut pieces 12a of the reactor vessel body 12 is moved and removed.

[0032] When the cut pieces 12a are separated from the reactor vessel body 12 by the vessel dismantling device 50, the drive device 62 moves the movable body 61 vertically downward relative to the beam 52 by a predetermined distance, and the cutting device 53 is placed in a position facing the inner peripheral wall surface of the reactor vessel body 12. At this time, the drainage device 71 (see FIG. 2) is operated as necessary to drain water from the reactor vessel body 12. Then, as described above, the drive device 62 moves the movable body 61 in the circumferential direction relative to the beam 52, and the cutting device 53 is moved in the circumferential direction, thereby cutting the reactor vessel body 12.

[0033] By repeatedly moving the cutting device 53 downward and in the circumferential direction by the driving device 62, the reactor vessel main body 12 is cut down to its lower part, as shown in Fig. 5. When the cutting work of the reactor vessel main body 12 is completed, the vessel dismantling device 50 is lifted using the crane device 92 and carried out to the outside of the reactor vessel main body 12.

[0034] [Effects of this embodiment] The vessel dismantling device according to the first embodiment comprises a stand 51 supported at the lower part inside the reactor vessel main body 12 (reactor vessel 11), a beam 52 (support member) arranged along the vertical direction and supported at its lower part by the stand 51, and a cutting device 53 supported on the beam 52 so as to be movable along the vertical direction and movably in the circumferential direction.

[0035] According to the vessel dismantling apparatus of the first aspect, a pedestal 51 is arranged under the reactor vessel main body 12, a beam 52 is erected on the pedestal, and a cutting device 53 is supported so as to be movable in the vertical and circumferential directions relative to the beam 52. Therefore, the crane device 92 only needs to concentrate on the work of carrying out the dismantled cut pieces 12a, and the cutting work of the reactor vessel main body 12 can be performed continuously, thereby improving the workability of the vessel dismantling work.

[0036] The vessel dismantling apparatus according to the second embodiment is the vessel dismantling apparatus according to the first embodiment, and further includes a pedestal 51 having a disk shape, the outer periphery of which is supported horizontally on the inner circumferential wall of the reactor vessel body 12. This allows the vessel dismantling apparatus 50 to be stably disposed inside the reactor vessel body 12.

[0037] The container dismantling apparatus according to the third aspect is the container dismantling apparatus according to the first or second aspect, and further includes a beam 52, a movable body 61 of which is supported so as to be movable in the vertical direction and in the circumferential direction, and a cutting device 53 is provided at the tip of a support arm 63 extending radially outward from the movable body 61. As a result, the beam 52 and the movable body 61 are disposed at the center of the reactor vessel body 12, and by moving the movable body 61, the cutting device 53 can be moved via the support arm 63, thereby making it possible to miniaturize the apparatus.

[0038] The vessel dismantling apparatus according to the fourth aspect is the vessel dismantling apparatus according to any one of the first to third aspects, and further includes a drainage device 71 that discharges water accumulated inside the reactor vessel body 12 to the outside. As a result, the shielding effect can be maintained by the water in the reactor vessel body 12, and since the cutting device 53 moves downward as it cuts the reactor vessel body 12, the drainage device 71 can discharge water inside the reactor vessel body 12 to the outside, thereby preventing the cutting device 53 from becoming waterlogged.

[0039] The vessel dismantling apparatus according to the fifth aspect is the vessel dismantling apparatus according to any one of the first to fourth aspects, and further includes a protective sheet 81 that suppresses the diffusion of chips of the reactor vessel body 12 cut by the cutting device 53. This makes it possible to suppress the diffusion of chips of the reactor vessel body 12 cut by the cutting device 53.

[0040] In the above-described embodiment, the vessel dismantling device 50 has been described as cutting the reactor vessel main body 12 (reactor vessel 11) in the circumferential direction, but it may also cut in the vertical direction or diagonally.

[0041] In the above-described embodiment, the container dismantling device 50 is described as cutting the reactor vessel main body 12 (reactor vessel 11), but the container is not limited to the reactor vessel main body 12, and may be any container contaminated with radioactive materials, such as a pressurizer. [Explanation of symbols]

[0042] 10 Pressurized Water Reactor 11 Reactor vessel 12 Reactor vessel body 13 Reactor vessel lid 18 Core Tank 19 Upper core support plate 20 Upper core plate 21 Core support rod 25 reactor core 26 Fuel assembly 50 Container dismantling equipment 51 Mounting stand 52 Beam (support member) 53 Cutting device 61 Mobile 62 Drive unit 63 Support arm 71 Drainage system 72 nozzles 73 Piping 74 Pump 81 Protective Sheet 82 Mounting part 83 Covering part 84 Connecting part 91 Support stand 92 Crane equipment

Claims

1. A container dismantling device for dismantling containers contaminated with radioactive materials, a stand supported at a lower portion inside the container; a support member disposed along the vertical direction and having a lower portion supported by the base; a cutting device supported by the support member so as to be movable in a vertical direction and in a circumferential direction; A container dismantling device comprising:

2. The stand has a disk shape, and an outer periphery thereof is supported horizontally on an inner periphery wall of the container. The container dismantling device according to claim 1.

3. The support member supports a movable body so that the movable body can move in a vertical direction and in a circumferential direction, and the cutting device is provided at a tip end of a support arm extending radially outward from the movable body. The container dismantling device according to claim 1.

4. A drainage device is provided to discharge water stored inside the container to the outside. The container dismantling device according to claim 1.

5. A protective sheet is provided to suppress the diffusion of chips from the container cut by the cutting device. The container dismantling device according to claim 1.

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