How to disassemble the lower mirror

Abstract

To efficiently dismantle the lower mirror. [Solution] The method for dismantling the lower mirror is a method for dismantling the lower mirror of equipment inside a reactor containment vessel, and includes the steps of: forming a temporary assembly consisting of the lower mirror and the lid member by fixing a lid member that closes the opening of the lower mirror to the lower mirror; inverting and installing the temporary assembly; and cutting at least the lower mirror of the inverted temporary assembly.

Description

Technical Field

[0001] This disclosure relates to a method for disassembling a lower mirror.

Background Art

[0002] Patent Document 1 discloses a technique for disassembling in-vessel structures in a reactor vessel in water stored in a working pool and removing the disassembled in-vessel structures from the working pool in relation to a method for disassembling a nuclear power plant.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in order to disassemble a nuclear power plant as described in Patent Document 1, it is necessary to cut the lower mirror of the equipment inside the reactor containment vessel into a plurality of cut pieces, store them in a waste container for storing radioactive waste, and then carry them out of the reactor containment vessel. However, the lower mirror is curved in a hemispherical shape, making the cutting operation difficult. In addition, secondary waste such as chips generated when cutting the upper part of the equipment above the lower mirror may accumulate on the lower mirror. Since the equipment inside the reactor containment vessel is often waste with a high radioactivity level, it is necessary to perform the operation while suppressing the scattering of secondary waste such as chips scattered during cutting to the surroundings.

[0005] This disclosure has been made to solve the above problems, and an object thereof is to provide a method for disassembling a lower mirror that can efficiently perform the disassembly operation of the lower mirror.

Means for Solving the Problems

[0006] To solve the above problems, this disclosure One aspectThe method for dismantling the lower mirror relating to this is a method for dismantling the lower mirror of equipment inside the reactor containment vessel. The method for dismantling the lower mirror includes the steps of forming a temporary assembly, inverting and installing the temporary assembly, and cutting the lower mirror. The step of forming the temporary assembly involves a lid member that closes the opening of the lower mirror. , in a position where the opening is facing upwards By fixing it to the lower mirror The aforementioned opening is closed. , a temporary assembly consisting of the lower mirror and the lid member is formed. top and bottom The step of inverting and installing involves inverting the temporary assembly and installing it. The step of cutting the lower mirror involves cutting at least the lower mirror from the inverted temporary assembly. Furthermore, a method for dismantling a lower mirror according to one aspect of the present disclosure is a method for dismantling a lower mirror of equipment located inside a reactor containment vessel, comprising the steps of: forming a temporary assembly consisting of the lower mirror and the lid member by fixing a lid member that closes the opening of the lower mirror to the lower mirror; inverting and installing the temporary assembly; and cutting at least the lower mirror from the inverted temporary assembly, wherein the equipment is located inside a hole formed so as to be recessed downward from the floor surface of a cavity provided inside the reactor containment vessel, the step of forming the temporary assembly is carried out inside the hole, and prior to the step of inverting and installing the temporary assembly, the method further includes the step of pulling the temporary assembly out of the hole, wherein in the step of pulling the temporary assembly out of the hole, a ring member having an inner diameter smaller than the maximum outer diameter of the lower mirror is attached to the lower side of the lower mirror, and the temporary assembly is pulled out of the hole by lifting the ring member from above. [Effects of the Invention]

[0007] According to the method for disassembling the lower mirror of this disclosure, the disassembly of the lower mirror can be carried out efficiently. [Brief explanation of the drawing]

[0008] [Figure 1] This is a longitudinal cross-sectional view showing a pressurized water reactor, which is the reactor to be dismantled according to this embodiment. [Figure 2] This is a schematic diagram showing a pressurized water reactor, with water stored inside according to the embodiment, with the reactor vessel lid removed, positioned inside the reactor building. [Figure 3] This is a flowchart showing the method for disassembling the lower mirror according to the embodiment. [Figure 4] This figure shows the step of forming a temporary assembly in the method for disassembling the lower mirror according to the embodiment. [Figure 5] This is a view from a first direction of the step of lifting the temporary assembly out of the hole in the method for dismantling the lower mirror according to the embodiment. [Figure 6] This is a view from a second direction of the suspension device used in the dismantling method of the lower mirror according to the embodiment. [Figure 7] This figure shows the step of inverting and installing the temporary assembly in the method for dismantling the lower mirror according to the embodiment. [Figure 8]This is a diagram showing the state where the temporary assembly is inverted in the method for disassembling the lower mirror according to the embodiment. [Figure 9] This is a diagram showing the state where the inverted temporary assembly is installed on the stand in the method for disassembling the lower mirror according to the embodiment. [Figure 10] This is a diagram showing the step of inverting the lower mirror in the method for disassembling the lower mirror according to a modified example of the embodiment. [Figure 11] This is a diagram showing the state during the process of inverting the lower mirror in the method for disassembling the lower mirror according to a modified example of the embodiment. [Figure 12] This is a diagram showing the state following that in FIG. 11 in the method for disassembling the lower mirror according to a modified example of the embodiment. [Figure 13] This is a diagram showing the state following that in FIG. 12 in the method for disassembling the lower mirror according to a modified example of the embodiment. [Figure 14] This is a diagram showing the state following that in FIG. 13 in the method for disassembling the lower mirror according to a modified example of the embodiment. [Figure 15] This is a diagram showing the state where the inverted temporary assembly is installed on the stand in the method for disassembling the lower mirror according to a modified example of the embodiment.

Mode for Carrying Out the Invention

[0009] Hereinafter, the method for disassembling the lower mirror according to the embodiment of the present disclosure will be described with reference to FIGS. 1 to 15. However, the present disclosure is not limited to only this embodiment.

[0010] <Embodiment> (Nuclear Reactor) FIG. 1 is a longitudinal sectional view showing a pressurized water reactor 1 which is a nuclear reactor to be disassembled according to the embodiment. The nuclear reactor uses light water as the reactor coolant and neutron moderator, forms high-temperature and high-pressure water that does not boil throughout the reactor core, sends this high-temperature and high-pressure water to a steam generator to generate steam by heat exchange, and sends this steam to a turbine generator to generate electricity. It is a pressurized water reactor 1 (PWR: Pressurized Water Reactor).

[0011] As shown in FIG. 2, the pressurized water reactor 1 is disposed in a reactor building pool 100 provided within a reactor building (not shown). A space capable of storing cooling water (water) is formed within the reactor building pool 100. The reactor building pool 100 of the present embodiment has, as a space, a first cavity 110 in which the pressurized water reactor 1 is disposed and a second cavity 120 disposed adjacent to the first cavity 110. The first cavity 110 has a first floor surface 111 on which an operator can walk. The second cavity 120 has a second floor surface 121 that is recessed from the first floor surface 111. That is, the second floor surface 121 is located below the first floor surface 111 in the vertical direction Dv. As a result, the second cavity 120 is formed as a space that is recessed below the first cavity 110 in the vertical direction Dv.

[0012] As shown in FIGS. 1 and 2, the pressurized water reactor 1 of the present embodiment includes a reactor vessel 2, a control rod drive device 3 (see FIG. 1), an upper core structure 5, and a lower core structure 6.

[0013] The reactor vessel 2 has a reactor vessel main body 21 and a reactor vessel head 22 (upper nozzle) such that in-vessel structures can be inserted therein. As shown in FIG. 2, the reactor vessel 2 is disposed inside a hole 15 formed so as to be recessed with respect to the first floor surface 111. The reactor vessel 2 is disposed in a state where a part thereof (specifically, the reactor vessel head 22) protrudes from the first floor surface 111.

[0014] As shown in FIGS. 1 and 2, the reactor vessel main body 21 is configured to be able to open at the top by removing the reactor vessel head 22. The reactor vessel main body 21 integrally has a body portion 211 and a lower nozzle 212. The body portion 211 is formed in a cylindrical shape extending in the vertical direction Dv. The lower nozzle 212 closes the lower end of the body portion 211. The lower nozzle 212 has a hemispherical shape that is recessed downward and has an opening 212a that opens upward.

[0015] The upper part of the reactor vessel body 21 has an inlet nozzle 23 (inlet nozzle holder) for supplying light water (coolant) as primary cooling water (water), and an outlet nozzle 24 (outlet nozzle holder) for discharging light water. In addition, the reactor vessel body 21 has an injection nozzle (injection nozzle holder) (not shown) formed separately from the inlet nozzle 23 and the outlet nozzle 24.

[0016] The reactor vessel lid 22 is attached to the top of the reactor vessel body 21. The reactor vessel lid 22 is fixed to the reactor vessel body 21 so as to be openable and closable by a plurality of stud bolts and nuts (not shown).

[0017] The upper core structure 5 is located inside the reactor vessel 2. The upper core structure 5 can be removed from the reactor vessel body 21 by moving it upward in the vertical direction Dv relative to the reactor vessel body 21. The upper core structure 5 in this embodiment has an upper core plate 51, an upper core support plate 52, an upper core support column 53, a guide tube 55, and a water level gauge support pipe (not shown). However, the upper core structure 5 does not have only the structure described above. The upper core structure 5 has other configurations not shown, such as a mixer, thermocouple lead-out pipes, and reinforcing beams.

[0018] As shown in Figures 1 and 2, the lower core structure 6 is located inside the reactor vessel 2. Many of the components of the lower core structure 6 are positioned vertically Dv below the upper core structure 5. The lower core structure 6 can be removed from the reactor vessel body 21 by moving it vertically Dv above the reactor vessel body 21. The lower core structure 6 is separable from the upper core structure 5 inside the reactor vessel body 21.

[0019] (How to disassemble the lower mirror) The following describes a method for disassembling the lower mirror according to the embodiment of this disclosure. The lower mirror 212 of the reactor vessel body 21 is dismantled by cutting it into multiple pieces. In this embodiment, the torso 211 of the reactor vessel body 21 is dismantled by cutting it in an appropriate manner, and after it is removed from the hole 15, the lower mirror 212 is dismantled.

[0020] Figure 3 is a flowchart showing a method for disassembling the lower mirror according to the embodiment of this disclosure. As shown in Figure 3, the method for dismantling the lower mirror S10 includes the steps of forming a temporary assembly 60 in step S11, pulling the temporary assembly 60 out of the hole 15 in step S12, inverting and installing the temporary assembly 60 in step S13, and cutting the lower mirror 212 in step S14.

[0021] Figure 4 shows the step of forming a temporary assembly in the method for disassembling the lower mirror according to the embodiment of this disclosure. In step S11, which forms the temporary assembly 60, the lid member 65 is fixed to the lower mirror 212, as shown in Figure 4. Step S11, which forms the temporary assembly 60, is carried out inside the hole 15. The lid member 65 is, for example, disc-shaped and closes the opening 212a of the lower mirror 212. The lid member 65 is fixed to a projection 212t provided on the inner circumferential surface of the lower mirror 212 via an appropriate bracket 67. The bracket 67 has, for example, a plate 67p positioned below the projection 212t and a spacer 67s interposed between the plate 67p and the lid member 65. The plate 67p is detachably fixed to the lid member 65 via the spacer 67s by bolts (not shown) or the like. The lid member 65 is fixed to the lower mirror 212 by sandwiching the projection 212t between itself and the plate 67p. Furthermore, the method for fixing the lid member 65 to the lower mirror 212 is not limited to the bracket 67; other methods may be used as appropriate.

[0022] By fixing the lid member 65 to the lower mirror 212 in this manner, a temporary assembly 60 consisting of the lower mirror 212 and the lid member 65 is formed. Secondary waste such as metal shavings generated when the body portion 211 (see Figures 1 and 2), which was located on the upper side of the lower mirror 212, was cut and dismantled may accumulate inside the lower mirror 212. By closing the opening 212a of the lower mirror 212 with the lid member 65, the scattering of secondary waste such as metal shavings into the surroundings is suppressed when the temporary assembly 60 is lifted out of the hole 15 or when the temporary assembly 60 is inverted.

[0023] Furthermore, a support frame 70 is installed on the underside of the lower mirror 212 at an appropriate time to support the lower mirror 212 from below. The support frame 70 is grounded on a third floor surface 113 located below the lower mirror 212. A ring member 80 is also attached to the underside of the lower mirror 212. The ring member 80 has an inner diameter smaller than the maximum outer diameter of the lower mirror 212. By abutting the ring member 80 against the lower mirror 212 from below, the ring member 80 is positioned to follow the hemispherical outer surface of the lower mirror 212. The ring member 80 is fixed to the lower mirror 212, for example, by welding or using appropriate fittings. The ring member 80 is also connected to the support frame 70 using bolts or the like.

[0024] Figure 5 is a view from a first direction of the step of lifting the temporary assembly out of the hole in the method for dismantling the lower mirror according to the embodiment of this disclosure. In step S12, the temporary assembly 60 is lifted out of the hole 15, as shown in Figure 5, by a crane 200 installed in the first cavity 110. In this embodiment, when lifting the temporary assembly 60 with the crane 200, a lifting device 90 is attached to the temporary assembly 60.

[0025] Figure 6 is a view from a second direction of the suspension device used in the dismantling method of the lower mirror according to the embodiment of this disclosure. As shown in Figures 5 and 6, the lifting device 90 comprises a suspension frame 91, a rail 92, and a trolley hoist 93 (see Figure 6).

[0026] The suspension frame 91 is formed in an inverted U shape when viewed from a first direction D1 along the horizontal plane, and integrally comprises a horizontal frame 91a and a pair of vertical frames 91b. The horizontal frame 91a extends in a second direction D2 that intersects the first direction D1 in the horizontal plane. The horizontal frame 91a can be suspended from a hook 201 of the crane 200 via a wire 202 or the like. The pair of vertical frames 91b extend downward from both ends of the horizontal frame 91a. The pair of vertical frames 91b pass on both outer sides of the lower mirror 212 in the second direction D2 and are rotatably connected to the ring member 80 around an axis (horizontal axis) 91s extending in the second direction D2. As shown in Figure 6, in this embodiment, the axis 91s is located in the center of the lower mirror 212 and the ring member 80 in the first direction D1 when viewed from the second direction D2. In this configuration, the central part of the lower mirror 212 in the first direction D1, which is part of the lower mirror 212, is supported so as to be rotatable around the axis 91s.

[0027] The rail 92 is joined to the transverse frame 91a and extends in the first direction D1. The trolley hoist 93 is mounted to be movable in a first direction D1 along the rail 92. The trolley hoist 93 has a chain or wire 93c with hooks 93s at its lower end.

[0028] As shown in Figure 5, in step S12, where the temporary assembly 60 is lifted out of the hole 15, the wire 202 is secured to the horizontal frame 91a of the lifting device 90 attached to the temporary assembly 60, and then the temporary assembly 60 is lifted out of the hole 15 by the crane 200. At this time, since the base 70 is connected to the ring member 80 joined to the lower mirror 212, when the temporary assembly 60 is lifted out, the base 70 is also lifted out together with the temporary assembly 60.

[0029] As shown in Figure 6, the lifted temporary assembly 60 is placed, for example, on the first floor surface 111 of the first cavity 110. The temporary assembly 60 is supported on a frame 70 placed on the first floor surface 111. Alternatively, the frame 70 may be configured not to be joined to the ring member 80, and the temporary assembly 60 may be placed on the first floor surface 111 via another frame (not shown) different from the frame 70. Furthermore, the lifted temporary assembly 60 may be placed in another location, such as on the second floor surface 121 of the second cavity 120.

[0030] In step S13, which involves inverting and installing the temporary assembly 60, a pair of vertical frames 91b are connected to the ring member 80, thereby inverting the temporary assembly 60 (lower mirror 112), which is supported to be rotatable around the axis 91s. To do this, the hook 93s of the trolley hoist 93 is locked to one end 80a of the ring member 80 in the first direction D1 relative to the axis 91s. The ring member 80 is then detached from the base 70.

[0031] Figure 7 shows the step of inverting and installing the temporary assembly in the method for disassembling the lower mirror according to the embodiment of this disclosure. Figure 8 shows the temporary assembly in an inverted state in the method for disassembling the lower mirror according to the embodiment of this disclosure. Figure 9 shows the inverted temporary assembly installed on the stand in the method for disassembling the lower mirror according to the embodiment of this disclosure. Subsequently, as shown in Figure 7, the crane 200 lifts the temporary assembly 60 and the ring member 80 from the frame 70 and inverts the temporary assembly 60. This is done by winding up the chain or wire 93c of the trolley hoist 93, which has a hook 93s attached to the end 80a of the ring member 80, while moving the trolley hoist 93 along the rail 92 to the other side of the first direction D1. Then, as shown in Figure 8, the temporary assembly 60 rotates around the axis 91s and is inverted. Once the lid member 65 of the temporary assembly 60 is facing downwards, the temporary assembly 60 is placed (connected) onto the frame 70. As a result, the inverted temporary assembly 60 is placed (installed) on the first floor surface 111 via the frame 70. After that, the ring member 80 is removed from the lower end 212 of the temporary assembly 60.

[0032] In step S14, which involves cutting the lower mirror 212, at least the lower mirror 212 is cut from the inverted temporary assembly 60. In this embodiment, the lower mirror 212 from the temporary assembly 60 is cut into multiple pieces. For cutting the lower mirror 212, for example, gas cutting or a disc saw with a cutting disc is used. At this time, since the lower mirror 212 is placed on the support frame 70 with its opening 212a facing downwards, the cutting work can be performed in a stable state. The cut pieces cut from the lower mirror 212 are stored in a waste container (not shown) and transported out of the reactor building (not shown).

[0033] (Effects and Benefits) In the lower mirror dismantling method S10 of the above embodiment, the temporary assembly 60 consisting of the lower mirror 212 and the lid member 65, which is formed by fixing the lid member 65 that closes the opening 212a of the lower mirror 212 to the lower mirror 212, is inverted and the lower mirror 212 is cut. This allows the lower mirror 212 to be cut with its hemispherical outer surface facing upward, stabilizing the lower mirror 212 and facilitating the cutting operation. Furthermore, since the opening 212a of the lower mirror 212 is closed by the lid member 65, even if secondary waste such as metal shavings generated when cutting the upper part of the reactor vessel 2 (body portion 211) of the lower mirror 212 has accumulated in the lower mirror 212, the scattering of such secondary waste into the surroundings can be suppressed. As a result, the dismantling operation of the lower mirror 212 can be carried out efficiently.

[0034] Furthermore, in the above embodiment, a temporary assembly 60 is formed by fixing a lid member 65 inside the hole 15, which is formed to recess downward from the first floor surface 111 of the first cavity 110, to the lower mirror 212 provided inside the hole 15. This allows the lid member 65 to be fixed before removing the lower mirror 212 from the hole 15, even if secondary waste such as metal shavings generated when cutting the upper part of the reactor vessel 2 that includes the lower mirror 212 has accumulated in the lower mirror 212. Therefore, the scattering of secondary waste such as metal shavings into the surroundings can be suppressed more effectively.

[0035] Furthermore, in the above embodiment, a ring member 80 having an inner diameter smaller than the maximum outer diameter of the lower mirror 212 is attached to the lower side of the lower mirror 212, and the temporary assembly 60 can be stably lifted out of the hole 15 by suspending the ring member 80 from above.

[0036] Furthermore, in the above embodiment, a portion of the lower mirror 212 is supported so as to be rotatable around the axis 91s, and by rotating the lower mirror 212 around the axis 91s, the temporary assembly 60 can be easily reversed. Furthermore, by using the ring member 80 to invert the temporary assembly 60, the need for complex operations such as attaching and detaching the crane hook inside the highly contaminated lower mirror 212 while simultaneously performing lifting and traversing operations with multiple cranes is eliminated. Therefore, the spread of contamination during the inversion of the temporary assembly 60 can be suppressed while also improving safety.

[0037] (Modified examples of the embodiment) Although embodiments of this disclosure have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments and may include design changes and the like that do not depart from the gist of this disclosure. In the above embodiment, a lifting device 90 or a ring member 80 was used to invert and install the temporary assembly 60, but the invention is not limited to this.

[0038] Figure 10 shows the step of inverting the lower mirror in a method for disassembling the lower mirror according to a modified embodiment. For example, as shown in Figure 10, the lower mirror 212 may be inverted while suspended by multiple cranes 300. Of the multiple cranes 300, the hook 301A of one crane 300A is, for example, attached to one end of the lower mirror 212 in the first direction D1. Of the multiple cranes 300, the remaining cranes 300B attach two hooks 301B to both sides of the lower mirror 212 in the second direction D2, at a position away from the position where hook 301A is attached, on the other side of the first direction D1. The hooks 301 (301A, 301B) are attached to appropriate bracket fittings 96 joined to the lower mirror 212.

[0039] Figure 11 shows the state in the process of inverting the lower mirror in a method for disassembling the lower mirror according to a modified embodiment. In step S13, which involves inverting and installing the temporary assembly 60, as shown in Figure 11, the lower mirror 212 is suspended in the air by cranes 300A and 300B, and a chain or wire 302 is extended from the hoist (not shown) of crane 300B. As a result, the lower mirror 212 rotates around the position where it is locked by hook 301A, and the end 212d on the side locked by hook 302B is lowered.

[0040] Figure 12 shows the state following Figure 11 in the method of disassembling the lower mirror according to a modified embodiment. Figure 13 shows the state following Figure 12 in the method of disassembling the lower mirror according to a modified embodiment. In this state, as shown in Figure 12, the hook 301B of the crane 300B is detached from the lower mirror 212. Next, as shown in Figure 13, the temporary assembly 60 is rotated approximately 180° around the vertical axis centered on the position where it was locked by the hook 301A.

[0041] Figure 14 shows the state following Figure 13 in the method for disassembling the lower mirror according to a modified embodiment. Next, as shown in Figure 14, the hook 301B of the crane 300B is reconnected to the lower mirror 212, and then the chain or wire 302 of the crane 300B is reeled in. As a result, the lower mirror 212 rotates around the position where it is locked by the hook 301A, the end 212d on the side locked by the hook 302B rises, and the temporary assembly 60 inverts so that the lid member 65 faces downward.

[0042] Figure 15 shows the state in which the inverted temporary assembly is placed on the stand in the method of disassembling the lower mirror according to a modified embodiment. Subsequently, as shown in Figure 15, the chain or wire 302 is extended using cranes 300A and 300B, lowering the inverted temporary assembly 60 and placing it on the temporary support platform 75 installed on the first floor surface 111. As a result, in step S14, which involves cutting the lower mirror 212, at least the lower mirror 212 can be easily cut from the inverted temporary assembly 60.

[0043] (Other embodiments) Although embodiments of this disclosure have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments and may include design changes and the like that do not depart from the gist of this disclosure. For example, in the above embodiment, the ring member 80 is attached to the underside of the lower mirror 212, and the temporary assembly 60 is pulled up from the hole 15 by suspending the ring member 80 from above, but the embodiment is not limited to this. The temporary assembly 60 may be pulled up from the hole 15 by other methods as appropriate, without using the ring member 80.

[0044] Furthermore, in the above embodiment, the lower mirror 212 of the reactor vessel 2 was dismantled using the dismantling method S10 for the lower mirror 212. However, the embodiment is not limited to this, and the same dismantling method S10 for the lower mirror 212 can also be applied when dismantling the lower mirror of other equipment such as pressurizers and steam generators installed in the reactor containment vessel.

[0045] <Note> The dismantling method S10 for the lower mirror 212 described in the embodiment can be understood, for example, as follows.

[0046] (1) The first embodiment of the method for dismantling the lower mirror 212 S10 is a method for dismantling the lower mirror 212 of equipment 2 inside the reactor containment vessel, and includes the steps of: S11 forming a temporary assembly 60 consisting of the lower mirror 212 and the lid member 65 by fixing a lid member 65 that closes the opening 212a of the lower mirror 212 to the lower mirror 212; S13 inverting and installing the temporary assembly 60; and S14 cutting at least the lower mirror 212 from the inverted temporary assembly 60. Examples of equipment 2 include the reactor vessel, pressurizer, and steam generator, which are installed inside the reactor containment vessel.

[0047] This allows the hemispherical lower mirror 212 to be cut while facing upwards, stabilizing the lower mirror 212 and facilitating the cutting process. Furthermore, since the opening 212a of the lower mirror 212 is closed by the cover member 65, even if secondary waste such as metal shavings generated when cutting the upper part of the equipment 2 that includes the lower mirror 212 accumulates in the lower mirror 212, it is possible to prevent the secondary waste from scattering into the surrounding area. As a result, the dismantling of the lower mirror 212 can be carried out efficiently.

[0048] (2) A method S10 for dismantling the lower mirror 212 according to a second embodiment is the method S10 for dismantling the lower mirror 212 according to (1), wherein the equipment 2 is provided inside a hole 15 formed so as to be recessed downward from the floor surface 111 of the cavity 110 provided in the reactor containment vessel, the step S11 for forming the temporary assembly 60 is carried out inside the hole 15, and the step S12 for lifting the temporary assembly 60 out of the hole 15 prior to the step S13 for inverting and installing the temporary assembly 60.

[0049] This allows the lid member 65 to be fixed in place before removing the lower mirror 212 from the hole 15, even if secondary waste such as metal shavings generated when cutting the upper part of the equipment 2 that includes the lower mirror 212 has accumulated in the lower mirror 212. Therefore, the scattering of secondary waste such as metal shavings into the surroundings can be more effectively suppressed.

[0050] (3) The third method of dismantling the lower mirror 212 S10 is the method of dismantling the lower mirror 212 S10 of (2), wherein in step S12 of lifting the temporary assembly 60 out of the hole 15, a ring member 80 having an inner diameter smaller than the maximum outer diameter of the lower mirror 212 is attached to the lower side of the lower mirror 212, and the temporary assembly 60 is lifted out of the hole 15 by lifting the ring member 80 from above.

[0051] This allows the temporary assembly 60 to be stably lifted out of the hole 15.

[0052] (4) The fourth method of dismantling the lower mirror 212 S10 is any one of the methods of dismantling the lower mirror 212 S10 from (1) to (3), wherein in step S13 of inverting and installing the temporary assembly 60, a part of the lower mirror 212 is supported so as to be rotatable around the horizontal axis 91s, and the temporary assembly 60 is inverted by rotating the lower mirror 212 around the horizontal axis 91s.

[0053] This allows the temporary assembly 60 to be easily reversed. [Explanation of Symbols]

[0054] 1… Pressurized water reactor 2…Reactor vessel (equipment) 3…Control rod drive mechanism 5…Upper core structure 6…Lower core structure 15…hole 21…Reactor vessel 22...Reactor vessel lid 23... Inlet nozzle 24…Outlet nozzle 51…Upper core plate 52…Upper core support plate 53… Upper core support column 55... Guide tube 60…Temporary assembly 65... Lid component 67…Bracket 67p...plate 67s…Spacer 70… Stand 75... Temporary stand 80... Ring component 80a...end 90... Lifting device 91... Hanging frame 91a... Horizontal frame 91b...Vertical frame 91s…axis (horizontal axis) 92... Rail 93... Trolley hoist 93c...wire 93s... Hook 96…Bracket hardware 100... Pool inside the reactor building 110... First Cavity (Cavity) 111…First floor surface (floor surface) 112…lower mirror 113...Third floor 120...Second cavity 121…Second floor surface 200... Crane 201... Hook 202... Wire 211... Torso 212…lower mirror 212a...Aperture 212d...end 212t…Protrusion 300..., 300A, 300B... Cranes 301, 301A, 301B... Hook 302... Wire 302B... Hook

Claims

1. A method for dismantling the lower mirror of equipment inside a reactor containment vessel, The process involves fixing a cover member that closes the opening of the lower mirror to the lower mirror in a position where the opening is facing upward, thereby closing the opening and forming a temporary assembly consisting of the lower mirror and the cover member. The process of installing the aforementioned temporary assembly by turning it upside down, The steps include cutting at least the lower mirror of the temporary assembly after inversion, Disassembly method for the lower mirror, including the part shown.

2. The aforementioned equipment is installed inside a hole formed so as to be recessed downward from the floor surface of the cavity provided within the reactor containment vessel. The process of forming the temporary assembly is carried out inside the hole. Prior to the step of inverting and installing the temporary assembly, the process further includes the step of lifting the temporary assembly out of the hole. The method for disassembling the lower mirror according to claim 1.

3. In the step of lifting the temporary assembly out of the hole, a ring member having an inner diameter smaller than the maximum outer diameter of the lower mirror is attached to the underside of the lower mirror, and the temporary assembly is lifted out of the hole by suspending the ring member from above. The method for disassembling the lower mirror according to claim 2.

4. A method for dismantling the lower mirror of equipment inside a reactor containment vessel, The process involves fixing a cover member that closes the opening of the lower mirror to the lower mirror, thereby forming a temporary assembly consisting of the lower mirror and the cover member. The process of inverting and installing the aforementioned temporary assembly, The steps include cutting at least the lower mirror of the temporary assembly after inversion, Includes, The aforementioned equipment is installed inside a hole formed so as to be recessed downward from the floor surface of the cavity provided within the reactor containment vessel. The process of forming the temporary assembly is carried out inside the hole. Prior to the step of inverting and installing the temporary assembly, the process further includes the step of lifting the temporary assembly out of the hole, In the step of lifting the temporary assembly out of the hole, a ring member having an inner diameter smaller than the maximum outer diameter of the lower mirror is attached to the underside of the lower mirror, and the temporary assembly is lifted out of the hole by suspending the ring member from above. How to disassemble the lower mirror.

5. In the step of inverting and installing the temporary assembly, a part of the lower mirror is supported so as to be rotatable around a horizontal axis, and the temporary assembly is inverted by rotating the lower mirror around the horizontal axis. A method for disassembling a lower mirror according to any one of claims 1 to 4.

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