JPS62189000A - Method of cutting contaminated piping and device using said method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for cutting contaminated pipes and an apparatus using the method.

INDUSTRIAL APPLICABILITY The present invention can be suitably used for cutting pipes highly contaminated with radioactive substances in nuclear power plants, cutting pipes in chemical plants contaminated with chemicals harmful to the human body, etc. .
[Prior Art] In nuclear power plants, plant equipment is contaminated with radioactive materials. Isotopes adhere to the inner walls of the piping in this equipment, and contamination by these isotopes reaches a high level at the end of the plant's life. This problem also applies to chemical plants that handle chemical substances that are harmful to the human body.

In the case of nuclear power plants, since radioactive materials are handled, the most important issue is to minimize radioactive contamination. Under normal nuclear power plant operating conditions, the radioactively contaminated area is kept to a minimum. This area is called the primary cooling system.

The primary cooling system consists of the equipment represented by the reactor pressure vessel that burns the fuel, and the reactor cooling system that circulates the coolant that sends the thermal energy generated by the combustion of the fuel to the power generation equipment. It consists of piping represented by system piping.

Until now, there has been no example of large-scale dismantling of primary cooling system equipment, such as decommissioning, in Japan. Only small-scale demolition work was carried out. Therefore, since it is a small-scale demolition, the spread of radioactive contamination due to demolition will be
It was in the acceptable range H. By decontaminating the radioactive contamination caused by the demolition process, it was possible to reduce the radioactively contaminated area to its original state.

However, at the end of the plant's life, it becomes necessary to dismantle the secondary cooling system. Abandoning such plants
In such cases, the disposal of highly contaminated equipment becomes an important issue.

As a specific example of the disposal of such highly contaminated equipment, there is a conventional example described in Japanese Patent Publication No. 57-50299. In this conventional example, plant equipment is soaked in mortar and then buried underground.

When dismantling plant equipment as in the conventional example described above, it is necessary to cut pipes that are part of the plant equipment. 2. Description of the Related Art Conventionally, as an example of a cutting process for pipes contaminated with radioactive substances, there is a conventional example described in Japanese Patent Application Laid-open No. 70522/1983. This conventional example involves cutting the piping with a high-speed cutter, grinder, or the like.

[Problem that the invention seeks to solve]

However, in the conventional example of the above-mentioned Japanese Patent Application Laid-Open No. 55-70522.

Because the pipes were cut using a grinder or high-speed cutter, it was inevitable that the radioactive materials adhering to the inner walls of the pipes would be released into the atmosphere and scattered during cutting. For this reason, problems of environmental pollution and human exposure to radiation for workers engaged in demolition processing could not be avoided.

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, it is an object of the present invention to provide a method for cutting contaminated pipes and an apparatus therefor that are free from the risk of scattering pollutants into the atmosphere.

[Means for solving problems]

In order to achieve the above-mentioned object, the first invention of the present application is to apply pressure to a part of contaminated piping to be cut, thereby occluding the flow path of the part and cutting the blocked part. This is a method of cutting piping.

Further, the second invention of the present application is provided with: a loading section into which a portion of contaminated piping to be cut is transported; a pressurizing device that pressurizes and closes the portion; and a cutting device that cuts the blocked portion. This is a contaminated piping cutting device characterized by comprising a cutting device main body and a drive device that moves the cutting device main body in the axial direction of the pipe.

[Effect]

According to the first invention of the present application, the following effects are obtained.

That is, it may be desirable to seal the contaminated part of the piping and cut the sealed part so that there is no risk of pollutants scattering into the atmosphere, and the cutting is performed after the part to be cut is heated and softened.

For example, if the piping is made of a hard material, the pressure applied can be reduced by heating and softening it. Therefore, the pressurizing device, such as a press machine, can be made smaller, and therefore the drive device can also be made smaller. Examples of heating methods include high frequency induction heating.

The temperature required for heating and softening is preferably close to the melting point of the pipe. This is because the higher the heating temperature, the higher the degree of softening, and the smaller the pressure required.

It is desirable to cut the sealing part while it is heated and softened, because by cutting it while it is softened, the cut surfaces will be welded and the scattering of contaminants at the cut point will be prevented.

In the second invention of the present application, a drive device is provided. By providing such a drive device, the cutting device main body can be moved to a desired cutting location.

〔Example〕

Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

In the following embodiment, an example of application to the case of decommissioning a nuclear power plant will be described.

1 to 4 show the basic steps of an embodiment of the method for cutting contaminated pipes, which is the first invention of the present application.

First, as shown in FIG. 1, a high-frequency induction heating coil 2 is attached to the pipe 1 to be cut so as to surround the outer wall of the pipe 1. A cable 3A is connected to the high-frequency induction heating coil 2, and the cable 3A is connected to a high-frequency current generator 4. By activating the high-frequency current generator 4, the pipe 1 to be cut can be locally heated by induction.

High-frequency induction heating of existing pipes is applied as a method for improving residual stress in pipe welds. The principle of high-frequency induction heating is that a coil is attached to the outside surface of the piping, the coil serves as the primary circuit, and the piping is used as the secondary circuit.The high-frequency current generated by an external high-frequency current generator is passed through a cable to the primary circuit. Flowing through the coil, this generates a secondary current in the piping that forms the secondary circuit,
It is possible to heat locally.

In the case of residual stress improvement in stainless steel piping welds, heating is usually carried out to about 500°C, but high frequency induction heating has the ability to heat up to over 1000°C.

As a result of heating, the piping can be softened in the heating section. The degree of heating is preferably close to the melting point of the pipe. For example, in the case of piping component material 5US304 commonly used in nuclear power plants, 130
It is desirable to heat the pipe to about 0° C. By heating it to near the melting point, it is possible to further soften the pipe.

Note that heating in a range exceeding the melting point is undesirable because the heated portion will melt.

Measurement of heating temperature can be determined by the correlation between heating current and heating time.

After heating to a predetermined temperature, the high-frequency induction heating coil 2 is taken out from the pipe 1, and as shown in FIG. 2, the heating part 5 is immediately flattened using a small press before the temperature of the heating part 5 drops. do. As a result of the pressing, the internal flow path in the heating section 5 is closed. By pressing before the temperature of the heating part drops, the force required for pressing can be reduced. For example, in the case of 5US304, the pressing force required for normal flattening is reduced to 1/1 by heating.
It can be reduced to 0-115.

In the case of general steel materials, the deformation resistance decreases as the temperature increases. In the case of stainless steel, which is often used in nuclear power plants, the deformation resistance is several kilograms at temperatures exceeding 1000°C.
g/m", which is about 1/10 of that at room temperature.

By reducing the applied pressure, the press machine can be made smaller. Therefore, the cutting device itself can be made smaller and more compact.

As shown in FIG. 2, when the pressing is finished, the closed heating section 5 is immediately cut off with a shear cutting machine, as shown in FIG. 3, before the temperature of the heating section 5 drops. By cutting before the temperature drops, the pressure for shear cutting can be reduced. Also, heat the piping to near the melting point.

By cutting before the temperature drops, welding can occur at the cut site. As a result, in addition to the effect of shear cutting that no chips are generated, it is possible to prevent radioactive substances from scattering into the atmosphere.

In addition, in FIG. 3, the closing portion 5 is cut using a grinder,
It can also be done with a cutter. In such a cutting method, by cutting before the temperature of the closed portion decreases, it is possible to prevent the generation of chips resulting from cutting, that is, the scattering of radioactive substances into the atmosphere.

Shear cutting is effective because no chips are generated during cutting even if the temperature of the closed portion 5 drops to room temperature.

By going through the cutting procedure as shown in FIGS. 1 to 3, as shown in FIG. 4, the contaminated pipe 1 can be cut with the cutting device 8 sealed. Since the cutting position 8 is in a sealed state, contaminants inside the pipe are not released into the external atmosphere when the pipe is cut, thereby preventing the occurrence of contamination and the spread of the contamination.

This reduces the risk of exposure to radiation during demolition work, and also minimizes decontamination work after the work is completed.

In the embodiments described above, the length of the heated region in FIG. 1 is determined by the properties of the material.

For example, if the plastic deformation ability (ductility) is small, it is difficult to make a rapid shape change during pressing, so the length of the heated part needs to be made longer.

Next, FIG. 5 shows a cross-sectional configuration diagram of an embodiment of a contaminated pipe cutting device according to the second invention of the present application.

In FIG. 5, the contaminated pipe cutting device 9 is provided with a cylindrical hollow loading section into which the pipe 1 to be cut is transported. This contaminated pipe cutting device 9 is provided with a press cutting device 10 for cutting the pipe 1 to be cut in the carry-in section. This press cutting device 10 is equipped with a shear cutting device. On the other hand, a drive device 11 is provided.

A roller IIB is provided within this drive device 11, and this roller rotates and moves the outer wall of the pipe 1 to be cut in the axial direction. A motor IIA for driving the roller is connected to this roller 11B. Cable 3B is connected to motor 11A, and motor IIA
It allows current to flow through. A high-frequency [(heating coil 2) is provided between the drive device 11 and the press cutting device 10. This coil 2 is constructed integrally with the outer wall of the drive device 11 and is supported. is connected to cable 3A.

Next, FIG. 6 shows a cross-sectional configuration diagram viewed from the direction AA in FIG. 5.

Press cutting scissors! 10 is a hydraulic pressure generator 12;

It consists of two pairs of hydraulic cylinders 13 provided at symmetrical positions so as to sandwich the pipe 1 to be cut between them, and a hydraulic piston 14 that transmits hydraulic pressure to the hydraulic cylinders 13. Two sets of these press cutting devices 10 are arranged in series in the axial direction of the plumber to be cut.

A press die 15 is attached to one piston in the axial direction, and a press die 15 is attached to the piping 1 side to be cut of the other piston 14.
A shear cutting blade is attached. In FIG. 5, the relationship between the shear cutting blade and the press die 15 is such that the press die 15 is on the driving device 11 side.

Each of the above-mentioned components is supported by a frame 16 and hooks 17, making it a J-type structure.

Next, the operation of the above embodiment will be explained.

First, the contaminated pipe cutting device 9 is attached to the pipe 1 to be cut. The installation is carried out by carrying the contaminated pipe 1 into the carrying-in section within the cutting device 9. Contaminated pipe cutting device! Support for f9 is
This can be done by supporting the piping 1 with a drive device [11].

Next, by driving the roller 11B, the cutting device I! 9 to a predetermined position. After that, the cutting device 9 is fixed to the pipe 1 to be cut. In addition, when installing the cutting device 9 on horizontal piping, the cutting device! It is necessary to keep the center of gravity of the cutting device 9 eccentric so that the cutting device 9 does not rotate around the horizontal piping axis.

As mentioned above, the movement of the pipe 1 to be cut in the axial direction is
Drive device! The cutting device i! rotates the roller 11B using the driving force of the motor IIA housed in the cutting device i! Move 9.

Note that remote control can be performed using a power source and a remote control panel provided via the moving cable 3B. As a result, it is possible to prevent the hair of workers from being exposed to external radiation.

After the cutting device 9 moves to a predetermined position, a high frequency current is passed through the high frequency induction heating coil 2 to locally heat the cut pipe 1. Immediately after raising the temperature of the pipe to a predetermined temperature, the contaminated pipe cutting device 9 is moved in the axial direction of the pipe 1 to be cut so that the press cutting device comes to the heated region. Continue pressing and cutting before the temperature of the heating part drops beyond the allowable range.

According to this embodiment, the method for cutting contaminated pipes shown in FIGS. 1 to 4 can be carried out.

In addition, in the above embodiment, the pipe can be continuously cut at predetermined locations by sequentially moving the cutting device. At this time, it may be necessary to support the piping so that it does not fall in the direction of gravity.

Next, a second embodiment of the contaminated pipe cutting device according to the present invention will be described.

FIG. 7 is a cross-sectional configuration diagram showing a case where the cutting device according to the embodiment is attached to the pipe 1 to be cut.

The driving device of the cutting device according to this embodiment is a movable table 11t (not shown) provided externally.

This mobile truck is provided with a boom 19 having a joint (not shown). A hydraulic cylinder 13 is provided at the tip of the boom 19 and is connected to a hydraulic piston 14. A press mold is provided at the tip of the hydraulic piston 14. The pipe 1 to be cut is carried in between the press die 15 and the tip 71 of the boom 19.

On the other hand, a boom 19 attached to such a movable truck is provided with a cylinder 13 and a piston 14 similar to those shown in FIG. 7 above, and a shear cutting blade is attached to the tip of the piston 14. Similarly, a boom 19 with a heating coil attached is prepared. The heating coil can also be provided integrally with the boom 19 having the press mold 15 shown in FIG. 7 above.

Next, the operation of this embodiment will be explained.

First, the heating coil is brought to the cutting location of the cutting pipe 1 by driving the movable trolley. After the piping portion is softened by heating with a heating coil, the portion is closed with a press die 15 (nine step).

A boom 19 having a shear cutting blade is moved to cut the blocked portion. The other four operations are the same as in the embodiment shown in FIG. 6 above.

According to this embodiment, it is possible to use pipes with complicated bends that make it difficult to attach an integrated contaminated pipe cutting device to the pipe as shown in FIG. 6, or to support an integrated cutting device. The cutting method shown in FIGS. 1 to 4 can also be applied to small-diameter thin-walled pipes that cannot be cut.

In addition, in this embodiment, the cutting blade, the press mold, and the heating coil can be integrated into one boom 19 and manufactured.

〔Effect of the invention〕

As explained above, according to the present invention, when cutting a portion of a pipe whose interior is highly contaminated, the contaminants inside the pipe are not released into the external atmosphere. In addition, the occurrence of contamination can be prevented.

Therefore, external exposure of workers engaged in cutting work can be prevented.

[Brief explanation of drawings]

Figures 1 to 4 are process diagrams for carrying out the contaminated pipe cutting device according to the invention of the present application No. 1, and Fig. 5 shows a first embodiment of the contaminated pipe cutting device according to the invention of the present application No. 2. FIG. 6 is a cross-sectional view, FIG. 6 is a vertical cross-sectional view, and FIG. 7 is a cross-sectional view showing a second embodiment of the contaminated pipe cutting device according to the present invention. 1... Piping to be cut, 2... High frequency induction heating coil. 3A, 3B... Cable, 4... High frequency current generator "t," 5... Heating section, 6... Small press machine, 7...
・Small shear cutting machine, 8... Cutting position, 9... Contaminated pipe cutting device, 10... Press/cutting section, 11...
Drive unit, lla...Motor, llb...Roller, 12...Hydraulic pressure generation position, 13...Hydraulic cylinder, 14...Hydraulic piston, 15...Press mold,]
6... Frame, 17... Hook, 18... Shear cutting blade, 19... Boom.

Claims (1)

[Scope of Claims] 1. A method for cutting contaminated piping, which comprises pressurizing a portion of contaminated piping to be cut, thereby closing a flow path in that portion and cutting the blocked portion. 2. A method for cutting contaminated piping according to claim 1, characterized in that the blocking portion is cut by shear cutting. 3. A method for cutting contaminated piping according to claim 1 or 2, characterized in that before pressurizing the portion of the piping to be cut, the portion is heated and softened. 4. A cutting device main body comprising: a loading section into which a section of contaminated piping to be cut is carried; a pressurizing device that pressurizes and closes the section; a cutting device that cuts the blocked section; A device for cutting contaminated pipes, comprising: a drive device that moves the main body of the device in the axial direction of the pipe. 5. The apparatus for cutting contaminated pipes according to claim 4, wherein the cutting machine is a shear cutting machine. 6. The apparatus for cutting contaminated piping according to claim 4 or 5, further comprising a heating device for heating and softening a portion of the contaminated piping to be cut.