JPH02307097A - Method and device for disassembling shielding body of nuclear reactor - Google Patents

Abstract

PURPOSE:To eliminate the danger of exposing and to allow safe and rapid disassembly by opening boring holes on the upper surface of a shielding wall and cutting the part contaminated with radioactivity of a shielding body in block units by the disassembling device. CONSTITUTION:The boring holes 12 are opened at proper intervals on the upper surface 11a of the shielding wall of the shielding body 10, and vertical frames 2 of the disassembling device A are inserted into the holes 12. The parts between the respective holes 12 are cut by a wire saw 6 to form cut grooves 12a. One of the vertical frames 2 is then inserted into the hole 12 and the other into the housing part (m) of the reactor core and the part between the hole 12 and the housing part (m) is cut to form the cut groove 12a, by which a small block part 11b is formed. The vertical frame 2 is inserted into the hole 12 and the wire saw 6 is put on between variable pulleys 9. The lower part of the block part 11b is horizontally cut to disassemble the shielding wall 11. This disassembling operation is executed by a remote operation, by which the danger of the operator being exposed is eliminated and the safe and rapid disassembly is executed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method and apparatus for dismantling a shield in a nuclear reactor accompanying the decommissioning of a nuclear power plant.

(Prior Art) In recent years, nuclear power plants have been constructed in various places due to the lack of absolute energy resources and economic efficiency. However, nuclear power plants are always faced with the danger of radioactivity, which conventional power plants do not have. Therefore, the dismantling of nuclear reactors due to decommissioning of nuclear power plants is extremely dangerous work for workers, and among them, the shielding body that shields the reactor core is radioactively contaminated, so the radioactively contaminated parts The building was dismantled separately from parts that were not contaminated with radioactivity.

(Problem to be solved by the invention) However, as mentioned above, when dismantling a shield contaminated with radioactivity, workers operated disassembly equipment to directly cut the contaminated parts, which resulted in radioactive contamination of the disassembly equipment. There was also a risk that workers would be exposed to radiation.

For this reason, the workers must be careful in the dismantling work, which requires a great deal of time and effort.

The present invention was made in view of such problems,
The purpose is to provide a method and device for dismantling shields in nuclear reactors that can be dismantled safely and quickly without the risk of workers being exposed to radiation during the dismantling work of shields contaminated with radioactivity. That's true.

(Means for achieving the object) The configuration of the present invention as a means for achieving the above object is as follows.
First, in a reactor shield consisting of a housing part that houses the reactor core and a shielding wall that shields the core, boring holes are bored at appropriate intervals along the periphery of the housing part on the upper surface of the shielding wall of the shielding body. After cutting vertically with a wire saw between the holes, between the boreholes, and between the borehole and the housing part, the wire saw is used to cut horizontally from the housing part to the borehole and dismantled. A method for dismantling a shield in a nuclear reactor, and secondly, a gate type consisting of a pair of vertical frames that are vertically expandable and a horizontal frame that is stretched across the upper ends of the vertical frames and that is horizontally expandable and contractible. In a nuclear reactor, the nuclear reactor is comprised of a support frame having a shape, upper and lower guide pulleys provided at the upper and lower ends of the vertical frame, and a wire saw stretched between the upper and lower guide pulleys. Thirdly, a gate-shaped support is present in the shield dismantling device and is composed of a pair of vertical frames that are vertically expandable and a horizontal frame that is stretched across the upper ends of the vertical frames and that is horizontally expandable and contractible. A frame, upper and lower guide pulleys provided at the upper and lower ends of the vertical frame, a rotatable variable pulley provided at the lower part of the lower guide pulley, and an area between the upper and lower guide pulleys and the variable pulley. The present invention relates to a device for dismantling a shield in a nuclear reactor, characterized in that it is constituted by a wire saw that is stretched over the wire.

(Function) According to the above configuration, the radioactively contaminated portion of the shield can be cut into blocks by the dismantling device, and the dismantling work can be remotely controlled by the dismantling device, so that the worker can Demolition work can be carried out easily and in a short time without exposing you to radioactivity.

(Example) Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 1 is a front view of the dismantling apparatus A of the present invention, showing a gate-shaped support frame 1, upper and lower guide pulleys 4.5 provided at the upper and lower ends of the support frame 1, and It is composed of a wire saw 6 that extends between upper and lower guide pulleys 4 and 5.

The support frame 1 consists of a pair of vertical frames 2 that are vertically expandable and a horizontal frame 3 that is installed on the upper end of the vertical frames and that is horizontally expandable and contractible, and is moved up and down by a support rod 7 connected to the horizontal frames. .

The horizontal frame 3 is divided into left and right parts at the center, and the ends are slidably inserted into the storage tube 3a, and are freely expanded and contracted laterally by a hydraulic cylinder or the like built in the storage tube 3a.

The vertical frame 2 consists of an upper frame 2a and a lower frame 2b, and like the horizontal frame 3, the lower frame 2
The upper end of b is slidably inserted into the upper frame 2a, and is freely expanded and contracted in the vertical direction by a hydraulic cylinder built into the upper frame 2a. The hydraulic cylinders of these vertical and horizontal frames 2.3 are all remotely controlled by an operating section (not shown). Further, an upper guide pulley 4 and a lower guide pulley 5 are provided at the upper end of the upper frame 2a and the lower end of the lower frame 2b, respectively, and a wire saw 6 is stretched between these upper and lower guide pulleys 4.5. There is.

The wire saw 6 is formed by attaching beads 7 having a diamond abrasive layer for cutting and spacers alternately to an endless steel wire. ).

Conventionally known beads are used, but beads 7 as shown in FIG. 9 may also be optionally used. This has a cylindrical shape with an insertion hole 7a in the axial center into which a wire is inserted, and a cutting blade 7b containing a diamond abrasive grain layer on the surface is formed in a curved state along the axial center. Note that the cutting blades 7b are formed with a certain interval, but the interval is a
>b is also optional, and the cutting blade 7
Of course, it is also optional to taper the width of b so that it gradually becomes wider from the front to the rear (or vice versa). Further, this wire saw 6 is always kept at a constant tension by a tension pulley (not shown) so that it can expand and contract as the vertical and horizontal frames 2.3 expand and contract.

FIGS. 2 and 3 show a dismantling device B that is equipped with a variable pulley 9 that can be rotated horizontally and vertically at the lower end of a vertical frame 2, and shows the support frame 1 and the upper and lower ends of the vertical frame 2. The upper and lower guide pulleys 4.5 provided in Pulley 5 is vertical frame 2
located on the side of the

The variable pulley 9 is provided at the tip of a rotating rod 9a that rotates around the tip of the vertical frame, and can be rotated vertically or horizontally by operation from an operating section (not shown). It is rotated vertically, and in the case of horizontal cutting, it is also rotated horizontally as shown in FIGS. 2 and 3.

Next, according to FIGS. 4, 7, and 8, the dismantling device A,
A method for disassembling the shield 10 using B will be described.

Since the shielding wall 11 of the shielding body 10 of this nuclear reactor M is radioactively contaminated, first the shielding wall 11 of the contaminated reactor core housing part m is dismantled. For this purpose, first, as shown in FIG. 4, boring holes 12 are bored at appropriate intervals in the shielding wall soil surface 11a of the shielding body 10 by core boring n. This boring hole 12 is bored along the periphery of the accommodating part m to approximately the same depth as the accommodating part m.

Next, as shown in FIG. 7, the vertical frame 2 of the demolition device A is inserted into the borehole 12, and each
The cut groove 12a is formed by cutting the radius with a wire saw 6. In this case, the horizontal frame 3 is adjusted to expand or contract according to the interval between the boreholes 12 so that the vertical frame 2 can be inserted into the borehole 12, and the vertical frame 3 is expanded or expanded according to the cutting situation of the wire saw 6. .

Next, after cutting between the boreholes 12 as described above, one side of the vertical frame 2 is inserted into the borehole 12, and the other is inserted into the core housing part m, as shown in (■) in Fig. 4. By cutting grooves 12a between each borehole 12 and the accommodating part m, a small partition 11b is formed in the radiation-contaminated shield M11.

Then, as shown in FIG. 8, the vertical frame 2 of the demolition device A is inserted into the borehole 12, and the wire saw 6, which is stretched between the variable pulleys 9, is used to cut both sides of the borehole 12 and the housing part m. The shielding wall 11 is cut horizontally across the grooves 12a and the lower part of the former section 11b.
is cut and dismantled into sections 11b.

In addition, in the case of vertical cutting, the dismantling device aA shown in FIG. 1 can be used, and in the case of horizontal cutting, the dismantling device B shown in FIG. It can be cut only with the dismantling device B shown in Figure 2.

(Effects of the Invention) The present invention has the following effects by having the above configuration.

■ Boring holes were bored at appropriate intervals along the periphery of the housing part on the upper surface of the shielding wall of the shielding body, and vertical cuts were made with a wire saw between the boreholes and between the borehole and the housing part. Thereafter, by horizontally cutting and dismantling the accommodation section through a borehole using the wire saw, it is possible to cut a large cross section at one time, thereby improving the dismantling efficiency of the shield in the nuclear reactor.

■ The dismantling device is supported by a gate-shaped support frame consisting of a pair of vertical frames that are vertically expandable and a horizontal frame that is horizontally expandable and stretched over the upper ends of the vertical frames, and the upper end of the vertical frames. The construction consists of upper and lower guide pulleys installed at the lower end, and a wire saw that spans between the upper and lower guide pulleys, making it possible to dismantle radioactively contaminated shielding walls remotely, as well as to dismantle them underwater. Since cutting is also possible, there is less risk of worker exposure to radiation.

■ The dismantling device is supported by a gate-shaped support frame consisting of a pair of vertical frames that are vertically expandable and a horizontal frame that is horizontally expandable and stretched over the upper ends of the vertical frames, and the upper end of the vertical frames. and an upper and lower guide pulley provided at the lower end, a variable pulley that is rotatable horizontally and vertically and provided at the lower part of the lower guide pulley, and a variable pulley that spans between the upper and lower guide pulleys and the variable pulley. By using a wire saw, there is no danger that workers will be exposed to radiation when dismantling a radioactively contaminated shield, and the dismantling can be done safely and in a short time.

[Brief explanation of drawings]

1 and 2 are a front view of the dismantling device of the present invention, FIG. 3 is a side view of the same, FIG. 4 is a process diagram showing a method for dismantling a shield, and FIG. 5 is a cross-sectional view of the shield. Figure 6 is a cross-sectional view of the reactor, Figure 7
8 is a sectional view of vertical cutting, FIG. 8 is a sectional view of horizontal cutting, and FIG. 9 is an enlarged perspective view of beads in a wire saw. A, B: Disassembly bag N M: Reactor m: Storage section
1: Support frame 2: MI frame
3:#! Frame 4: Upper guide pulley 5: Lower guide pulley 6: Wire saw 9: Variable pulley 1o: Water shielding body 11: Shielding wall 12a: Boring hole

Claims (3)

[Claims] (1) In a reactor shield consisting of a housing part that houses the reactor core and a shielding wall that shields the core, boreholes are bored at appropriate intervals along the periphery of the housing part on the upper surface of the shielding wall of the shielding body. A hole is drilled, vertical cuts are made between the boreholes and between the borehole and the accommodating part using a wire saw, and then horizontal cutting is performed from the accommodating part to the borehole using the wire saw to disassemble the material. A method for dismantling shields in nuclear reactors. (2) A gate-shaped support frame consisting of a pair of vertical frames that are vertically expandable and a horizontal frame that is horizontally expandable and stretched over the upper ends of the vertical frames; 1. A device for dismantling a shield in a nuclear reactor, comprising an upper and lower guide pulley provided at the lower end and a wire saw stretched between the upper and lower guide pulleys. (3) A gate-shaped support frame consisting of a pair of vertical frames that are vertically expandable and a horizontal frame that is horizontally expandable and stretched over the upper ends of the vertical frames; It is composed of an upper and lower guide pulley provided at the lower end, a rotatable variable pulley provided at the lower part of the lower guide pulley, and a wire saw stretched between the upper and lower guide pulleys and the variable pulley. A device for dismantling a shield in a nuclear reactor, characterized by: