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 disassembling device for disassembling a container contaminated with radioactive substances.

Background Art

[0002] In a nuclear power plant, a reactor containment vessel is erected on a solid ground such as rock, and a reactor is disposed inside. The reactor is composed of in-vessel structures such as fuel disposed inside a reactor vessel. When disposing of the reactor, after removing the in-vessel structures from inside the reactor vessel, the reactor vessel is cut and disassembled. As a technique for disassembling the reactor vessel, for example, there are those described in Patent Documents 1 and 2.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] When disassembling a reactor vessel, the disassembling device is suspended and supported by a crane, and the disassembling device is moved to cut the reactor vessel. In this case, not only is the disassembling device suspended and supported by the crane, but it is also necessary to carry out the cut pieces generated by cutting the reactor vessel by the crane. Therefore, after the crane moves the disassembling device to cut the reactor vessel, it is necessary to support the cut pieces and move them to a predetermined position, and there is a problem that the disassembling work takes a long time.

[0005] The present disclosure solves the above-described problems, and an object thereof is to provide a container disassembling device that improves the workability of container disassembling work.

Means for Solving the Problems

[0006] To achieve the above objective, the container dismantling apparatus of the present disclosure is a container dismantling apparatus for dismantling a container contaminated with radioactive material, comprising: a frame supported in the lower part inside the container; a support member arranged vertically and whose lower part is supported by the frame; and a cutting device supported on the support member so as to be movable vertically and circumferentially. [Effects of the Invention]

[0007] The container dismantling apparatus of this disclosure can improve the work efficiency of container dismantling operations. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a longitudinal cross-sectional view of a pressurized water reactor. [Figure 2] Figure 2 is a schematic front view showing the container dismantling apparatus of this embodiment. [Figure 3] Figure 3 is a schematic plan view of the container dismantling apparatus. [Figure 4] Figure 4 is a schematic diagram illustrating the container dismantling process using a container dismantling device. [Figure 5] Figure 5 is a schematic diagram illustrating the container dismantling process using a container dismantling device. [Modes for carrying out the invention]

[0009] 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.

[0010] <Pressurized Water Reactor> Figure 1 is a longitudinal cross-sectional view of a pressurized water reactor.

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

[0012] As shown in Figure 1, in a pressurized water reactor 10, the reactor vessel 11 is composed of a reactor vessel body 12 and a reactor vessel lid 13 attached to the top of the reactor vessel, so that internal reactor structures can be inserted inside. The reactor vessel lid 13 is fixed to the reactor vessel body 12 so as to be openable and closable by a plurality of stud bolts 14 and nuts 15.

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

[0014] The core vessel 18 is supported below by a lower core support plate 22, the lower core support plate 22 being positioned and supported on the inner wall surface of the reactor vessel body 12 by a positioning member 23 on its outer circumference. The core vessel 18 is supported below by a lower core plate 24. The core 25 is composed of numerous fuel assemblies 26, with numerous control rods 27 arranged inside, and the control rods 27 are insertable into the fuel assemblies 26. The upper core support plate 19 has numerous control rod cluster guide tubes 28 fixed to it, through which control rods 27 can be inserted. The reactor vessel lid 13 is hemispherical in shape, and a control rod drive device 29 is located there, with multiple control rod cluster drive shafts 30 inserted into the control rod cluster guide tubes 28, and control rods 27 connected to their lower ends. The control rod drive device 29 controls the reactor output by inserting and removing each control rod 27 from the core 25.

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

[0016] <Container dismantling equipment> Figure 2 is a schematic front view representing the container dismantling apparatus of this embodiment, and Figure 3 is a schematic top view representing the container dismantling apparatus.

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

[0018] The container disassembling device 50 includes a gantry 51, a beam (supporting member) 52, and a cutting device 53.

[0019] The gantry 51 is supported at the lower part inside the reactor vessel main body 12. The gantry 51 has a disk shape, and its outer peripheral part is supported horizontally by the inner peripheral wall part of the reactor vessel main body 12. That is, although the reactor vessel main body 12 is in a state where the in-vessel structures have been carried out, the positioning members 23 are attached to the inner peripheral wall part. A plurality of positioning members 23 are provided at intervals in the circumferential direction and positionally support the already carried-out lower core support plate 22 (see FIG. 1). The outer peripheral part of the gantry 51 is supported horizontally by the plurality of positioning members 23. However, the gantry 51 is not limited to a disk shape. Also, the gantry 51 is not limited to a configuration supported by the positioning members 23, and for example, it may be supported by a plurality of in-vessel instrumentation guide pipes penetrating the lower mirror of the reactor vessel main body 12.

[0020] The beam 52 is arranged along the vertical direction inside the reactor vessel main body 12. The beam 52 has a cylindrical shape, and its lower part is supported by the gantry 51. However, the beam 52 is not limited to a cylindrical shape. The beam 52 is arranged at the central position of the reactor vessel main body 12.

[0021] The cutting device 53 is movable along the vertical direction on the beam 52 and is supported so as to be movable 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 or the like.

[0022] The beam 52 is supported such that the movable body 61 can move freely both vertically and circumferentially. The movable body 61 is movable vertically and circumferentially by a drive device 62. The drive device 62 may, for example, have a drive motor and a rack and pinion mechanism, allowing the movable body 61 to move vertically relative to the beam 52. Alternatively, the drive device 62 may have, for example, a drive motor and a planetary gear mechanism, allowing the movable body 61 to move circumferentially 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 existing mechanisms may be adopted as appropriate.

[0023] The movable body 61 has support arms 63 extending radially outward from its outer circumference. The support arms 63 are positioned along the radial direction of the reactor vessel body 12, with one end connected to the movable body 61 and a cutting device 53 attached to the other end.

[0024] Therefore, when the drive unit 62 moves the mobile body 61 vertically along the beam 52, the cutting device 53, which is supported by the mobile body 61 via the support arm 63, can be moved vertically with a predetermined gap between it and the inner circumferential wall surface of the reactor vessel body 12. Also, when the drive unit 62 moves the mobile body 61 circumferentially relative to the beam 52, the cutting device 53, which is supported by the mobile body 61 via the support arm 63, can be moved circumferentially with a predetermined gap between it and the inner circumferential wall surface of the reactor vessel body 12.

[0025] The cutting device 53 may be made movable along the radial direction of the reactor vessel body 12 relative to the beam 52 and 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, a pipe 73, and a pump 74. The nozzle 72 is located inside the reactor vessel body 12. The pipe 73 has the nozzle 72 attached to one end and is led out to the outside of the reactor vessel body 12 at the other end, where the pump 74 is attached. By driving the pump 74, the nozzle 72 can draw in water stored in the reactor vessel body 12 via the pipe 73 and discharge it to the outside through the pipe 73.

[0027] The vessel dismantling device 50 is equipped with a protective sheet 81. The protective sheet 81 is a fire-resistant 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 that are cut by the cutting device 53. The protective sheet 81 has a mounting portion 82 that is positioned on the inside of the reactor vessel body 12 along the vertical direction, a covering portion 83 that is positioned on the outside of the reactor vessel body 12 along the vertical direction, and a connecting portion 84 that connects the mounting portion 82 and the covering portion 83. The mounting portion 82 of the protective sheet 81 is supported by the support arm 63. However, it is preferable that the protective sheet 81 is provided so as to be movable relative to the support arm 63.

[0028] <Container disassembly method> Figure 4 is a schematic diagram illustrating the container dismantling process using a container dismantling device.

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

[0030] The vessel dismantling device 50 is assembled with a frame 51, a beam 52, and a cutting device 53, and is transported into the reactor vessel body 12 using a crane device 92. At this time, the frame 51 of the vessel dismantling device 50 is supported by a positioning member 23 of the reactor vessel body 12. Then, the drive device 62 moves the movable body 61 vertically relative to the beam 52, positioning the cutting device 53 opposite the inner circumferential wall surface of the reactor vessel body 12. At this point, the drive device 62 moves the movable body 61 circumferentially relative to the beam 52, and moves the cutting device 53 circumferentially to start cutting 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] Then, as shown in Figure 4, when the cutting device 53 moves 360 degrees in the circumferential direction, the reactor vessel body 12 is cut in the circumferential direction, forming a ring-shaped cut piece 12a. During the cutting of the reactor vessel body 12 by the cutting device 53, or just before the cutting of the reactor vessel body 12 by the cutting device 53 is completed, the crane device 92 is activated to hold the cut piece 12a that has been separated from the reactor vessel body 12. It is preferable that the crane device 92 holds the cut piece 12a at multiple locations. By activating the crane device 92, the cut piece 12a is transported to a predetermined storage location. At this time, the protective sheet 81 covering the cut piece 12a of the reactor vessel body 12 moves and is removed.

[0032] When the cut piece 12a is separated from the reactor vessel body 12 by the vessel dismantling device 50, the drive device 62 moves the movable body 61 vertically downward by a predetermined distance relative to the beam 52, and positions the cutting device 53 opposite the inner circumferential wall surface of the reactor vessel body 12. At this time, if necessary, the drainage device 71 (see Figure 2) is activated to drain water from the reactor vessel body 12. Then, as described above, the drive device 62 moves the movable body 61 circumferentially relative to the beam 52, and the cutting device 53 is moved circumferentially to cut the reactor vessel body 12.

[0033] By repeatedly moving the cutting device 53 downwards and circumferentially using the drive device 62, the reactor vessel body 12 is cut down to the bottom, as shown in Figure 5. Once the cutting of the reactor vessel body 12 is complete, the vessel dismantling device 50 is lifted using the crane device 92 and transported outside the reactor vessel body 12.

[0034] [Effects of this embodiment] The first embodiment of the vessel dismantling apparatus comprises a frame 51 supported in the lower part inside the reactor vessel body 12 (reactor vessel 11), a beam 52 (support member) arranged vertically and whose lower part is supported by the frame 51, and a cutting device 53 supported on the beam 52 so as to be movable vertically and circumferentially.

[0035] According to the first embodiment of the vessel dismantling apparatus, a frame 51 is placed at the bottom of the reactor vessel body 12, a beam 52 is erected on the frame, and a cutting device 53 is supported on the beam 52 so as to be movable in the vertical and circumferential directions. Therefore, the crane device 92 only needs to concentrate on the work of transporting the dismantled cut pieces 12a, and the cutting work of the reactor vessel body 12 can be performed continuously, thereby improving the work efficiency of the vessel dismantling work.

[0036] The second embodiment of the vessel dismantling apparatus is the same as the first embodiment, further comprising a frame 51 which is disc-shaped and whose outer circumference is horizontally supported by the inner circumferential wall of the reactor vessel body 12. This allows the vessel dismantling apparatus 50 to be stably positioned inside the reactor vessel body 12.

[0037] The third embodiment of the vessel dismantling apparatus is a vessel dismantling apparatus according to the first or second embodiment, further comprising a beam 52 supported by a movable body 61 that is movable both vertically and circumferentially, and a cutting device 53 is provided at the tip of a support arm 63 that extends radially outward from the movable body 61. This allows the beam 52 and the movable body 61 to be positioned at the center of the reactor vessel body 12, and the cutting device 53 to be moved via the support arm 63 by moving the movable body 61, thereby enabling miniaturization of the apparatus.

[0038] The fourth embodiment of the vessel dismantling apparatus is a vessel dismantling apparatus according to any one of the first to third embodiments, further comprising a drainage device 71 for discharging water stored inside the reactor vessel body 12 to the outside. This allows the shielding effect to be maintained by the water in the reactor vessel body 12, while as the cutting device 53 cuts the reactor vessel body 12, the cutting device 53 moves downward, and by discharging the water inside the reactor vessel body 12 to the outside with the drainage device 71, water ingress of the cutting device 53 can be suppressed.

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

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

[0041] In the embodiments described above, the container dismantling device 50 was described as cutting the reactor vessel body 12 (reactor vessel 11). However, the container is not limited to the reactor vessel body 12, but can be any container contaminated with radioactive material, 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 rods 25 Core 26 Fuel assembly 50 Container dismantling equipment 51. Stand 52 Beam (support member) 53 Cutting device 61 Mobile Unit 62 Drive unit 63 Support Arm 71 Drainage system 72 nozzles 73 Piping 74 pumps 81 Protective Sheet 82 Mounting part 83 Covering part 84 Connecting part 91 Support stand 92 Crane equipment

Claims

1. In a container dismantling device for dismantling containers contaminated with radioactive materials, A support structure located at the bottom of the interior of the aforementioned container, A support member arranged vertically and whose lower part is supported by the frame, A cutting device is supported on the support member so as to be movable along the vertical direction and in the circumferential direction, A container dismantling device equipped with the following features.

2. The aforementioned support is disc-shaped, and its outer circumference is supported horizontally by the inner circumferential wall of the container. The container dismantling apparatus according to claim 1.

3. The support member supports the movable body so that it can move vertically and circumferentially, and the cutting device is provided at the tip of a support arm that extends radially outward from the movable body. The container dismantling apparatus according to claim 1.

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

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

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