JP3092619B1 - Submerged cutting device - Google Patents

Abstract

A maintenance work for a cutting actuator of an underwater cutting device is performed in a short time. In an underwater cutting device for structures in a nuclear reactor, a torch mast (6b) for holding a plasma torch (7) and a hood mast (6a) for holding a gas recovery hood (11) have different structures, and a hinge (15) is provided on the torch mast (6b). When the plasma torch 7 is maintained,
2 is opened, the food mast 6a and the torch mast 6b are separated, the plasma torch 7 and the torch mast 6b are lifted into the air using the jib crane 13, and the gas recovery hood 11, which is a high radiation dose source, is always placed in water. Radiation exposure of workers during maintenance of the torch 7 is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a submerged cutting apparatus used for cutting in liquid.

[0002]

2. Description of the Related Art Dismantling work for preventive maintenance or decommissioning of a nuclear power plant involves the construction of nuclear reactors, large vessels,
In addition, in order to reduce the bulk of the structure after dismantling and to perform the volume reduction with high efficiency and safely from the viewpoint of radiation exposure, the cutting operation of devices having various shapes is performed in water.

[0003] In other words, when cutting an existing structure, a large container, or equipment in a nuclear power plant, the object to be cut is often activated or has radioactive substances attached thereto. Cutting work is performed in water for the purpose of shielding radiation and preventing scattering of radioactive materials.

[0004] For this reason, the cutting device performs a cutting operation by remote control by immersing a part or the whole of the device in water.

However, since the maintenance of the cutting actuator for actually performing the cutting operation is performed in the air, it is necessary to lift the entire cutting device into the air or to separate the cutting actuator from the cutting device in water and lift it alone into the air. There is.

However, when the cutting operation is resumed after the maintenance is completed, it takes a long time to reset the cutting device or the cutting actuator.

Further, in the case of employing a method which may generate gas at the time of cutting, such as a thermal cutting method, using a cutting apparatus, a method of recovering generated gas is disclosed in JP-A-10-293191 and JP-A-10-293191.
No. 11,237,791 discloses an air collecting cover and a gas recovery hood, respectively.

[0008]

As described above, since the maintenance of the cutting actuator for actually performing the cutting operation is performed in the air, the entire cutting device is pulled into the air or the cutting actuator is moved from the cutting device in the water. It is necessary to separate it and lift it alone.

However, it is difficult and time-consuming to lift the entire cutting device into the air and to separate the cutting actuator from the entire cutting device in water. In addition, when maintenance is completed and the cutting operation is resumed, the cutting device or the cutting device is required. It takes a lot of time to reset the actuator.

In addition, since the known air collecting cover is installed near the water surface, the efficiency of air bubble collection is particularly poor when air bubbles rise slowly or when gas is diffused by the flow in the liquid pool. There is a problem that.

Further, since the latter gas recovery hood is set above the vicinity of the gas generating source, the recovery efficiency is high. However, in the process of recovering the gas containing the radioactive material, the radioactive material is confined in a narrow part or the like. Adheres and becomes a high dose source.

Further, when the gas recovery hood and the cutting actuator have an integrated structure, the gas recovery hood, which is a high dose source, rises in the air during maintenance of the cutting actuator, and the radiation exposure dose of the maintenance worker increases. Challenges arise.

Therefore, it is necessary to have a structure in which the cutting actuator is lifted into the air without being separated from the cutting device body. In this case, the time required for restarting the cutting operation after the maintenance is completed is greatly reduced.

As described above, in an apparatus for remotely cutting structures in a nuclear power plant in a liquid pool, in order to perform maintenance of a cutting actuator in a short time, with a low dose equivalent, and safely, the following is required. There is such a problem.

(1) When performing maintenance on the cutting actuator, it is necessary to lift the cutting device body or the cutting actuator alone into the air, so that it takes time to reset the device after maintenance is completed.

(2) In a cutting apparatus which employs a thermal cutting method for a cutting actuator and is equipped with a gas recovery hood for recovering gas generated at the time of cutting, the process of recovering a gas containing radioactive substances requires a gas recovery process. Radioactive material adheres to the narrow part of the hood and becomes a high dose source.

(3) When the collecting hood and the cutting actuator, which are high-dose sources, have an integrated structure, the collecting hood rises in the air during maintenance of the cutting actuator, and the exposure dose equivalent of the maintenance worker increases.

Accordingly, a main object of the present invention is to perform maintenance of a cutting actuator of a cutting device in a liquid pool in a short time.

As another object, in addition to the above-mentioned main object, a structure is provided in which only a limited portion including the cutting actuator is pulled into the air without separating the cutting actuator from the cutting device main body. The task is to reduce the radiation exposure dose and perform it safely.

Further, in addition to the above-mentioned main object, it is an object of the present invention to reduce the use of a high-dose source in a cutting apparatus equipped with a gas collecting hood for collecting gas generated during cutting.

[0021]

A first means is a traveling vehicle that straddles a liquid pool, a transverse vehicle mounted on the traveling vehicle and moves in a direction orthogonal to a direction in which the traveling vehicle moves, and the first traveling vehicle. A submerged cutting device provided with a holding mechanism for supporting a cutting actuator, and a rotating mechanism for rotating at least a part of the holding mechanism together with the cutting actuator in a vertical direction, and holding the cutting actuator. Rotating and holding the holding mechanism (mast) in the vertical direction to bend the cutting actuator from the liquid pool liquid to the air above the liquid surface without disconnecting the cutting actuator from the entire cutting device, and performing maintenance on the cutting actuator, After maintenance, the cutting actuator rotates the holding mechanism in the opposite direction and puts it in the liquid pool liquid for cutting. To enable open, the advantages of shortening the working time for maintenance.

The second means is a submerged cutting apparatus in which the gas recovery hood for recovering gas generated at the time of cutting is supported by another holding mechanism different from the holding mechanism of the cutting actuator in the first means, In addition to the function and effect of the first means, the holding mechanism of the gas recovery hood and the holding mechanism of the cutting actuator for collecting generated gas at the time of cutting generated when the thermal cutting method is employed for the cutting actuator are separately provided. When replacing the cutting actuator main body or a part of the cutting actuator due to wear or malfunction, pull up only the cutting actuator and its holding mechanism into the air while leaving the gas recovery hood and its holding mechanism in the liquid, and remove the cutting actuator. By performing maintenance work, the gas collection hood to which radioactive substances adhere is simultaneously exposed to the air, making it easier for workers to be exposed to radiation. To avoid the situation where that, action and effect that can be maintenance work of safely cutting actuator is obtained.

The third means is the second means, wherein the holding mechanism of the gas recovery hood is a tubular structure having a hollow cross section, and the inside of the hollow cross section is connected to the gas recovery hood, and the tubular structure is connected to the gas recovery hood. This is a submerged cutting device that also serves as a gas discharge passage from the collection hood. In addition to the function and effect of the second means, the holding mechanism can also be used as a passage for discharging gas from the upper end of the gas collection hood. ,
The new flexible gas recovery hose does not increase the number of parts contaminated with radioactive material, and the gas recovery hose does not act as a vibration source and adversely affect the cutting accuracy of the cutting actuator. The function and effect of contributing to reduction of radiation exposure and accurate cutting work can be obtained.

The fourth means is the third means, wherein the tubular structure is provided.
Inside the object, through high-pressure water generation equipment and high-pressure water supply hose
The connected spray nozzle is a submerged cutting device provided as a means for cleaning the inside of the tubular structure. In addition to the effect of the third means, the tubular structure is provided by means for cleaning the inside of the tubular structure. Narrow portions such as the connection between the inside and the tubular structure and the gas recovery hood are cleaned, and radioactive substances attached to the narrow portion such as the connection between the tubular structure and the connection between the tubular structure and the gas recovery hood are removed. This makes it possible to reduce the atmospheric dose of the cutting device, and obtain an effect of reducing the radiation exposure of the worker during the cutting operation or maintenance of the device body.

[0025]

Embodiments of the present invention will be described below with reference to the drawings.

The first embodiment is as follows.

Although common to each embodiment of the present invention, water is poured into a pool A in a reactor building in which a reactor is housed, and a material 8 to be cut in the water of the pool A is used as a material to be cut. An embodiment is shown in which a furnace internal structure taken out of a container is placed and the material to be cut 8 is cut underwater by a cutting device.

FIGS. 1 and 2 show an underwater plasma cutting apparatus employing a plasma torch 7 used in water as a cutting actuator.

In the following, an embodiment of the present invention will be described using an underwater plasma cutting apparatus, but the cutting method is not necessarily limited to the underwater plasma cutting method.
This includes other thermal cutting methods and mechanical cutting methods.

In FIG. 1 and FIG. 2, reference numeral 1 denotes a running rail fixed to both sides of the pool A. Similarly, reference numeral 2 denotes a traveling vehicle that travels on the traveling rail 1 along the traveling rail 1 across the pool A, and the traversing rail 3 is fixed to the traveling vehicle 2 in a direction orthogonal to the traveling rail 1.

In FIG. 1 and FIG. 2, reference numeral 4 denotes a trolley traveling on the traverse rail 3 along the traverse rail 3.
Is equipped with a mast 6 via a mast drive device 5. The mast 6 can move to an arbitrary location on the surface of the pool A by the traveling functions of the traveling carriage 2 and the traversing carriage 4.

The mast driving device 5 drives the mast 6 so as to be able to turn around the mast central axis in the longitudinal direction of the mast 6, and is combined with the mast 6 so as to drive the mast 6 in the elevating direction. Therefore, the mast 6 can perform a vertical movement and a turning movement. The plasma torch 7 provided at the lower end of the mast 6 is supplied with a power supplied from a plasma power supply (not shown in the drawing).
A main arc 9 is generated between them, and the material to be cut 8 is cut by the thermal energy.

Further, since the plasma torch 7 is attached to the mast 6 via the torch swing mechanism 10, the orientation of the plasma torch 7 can be freely set by the torch swing mechanism 10 to the torch elevation angle, which is the vertical direction angle. Can be changed to

The plasma torch 7 changes the respective traveling operations of the traveling vehicle 2 and the traversing vehicle 4, the respective operations of turning and lifting the mast 6 by the mast driving device 5, and changing the vertical direction by the torch swing mechanism 10. The position and the posture can be freely changed by a total of five operations including the operation.

The degree of freedom of the tip of the plasma torch 7 is a total of five degrees of freedom by the above-described total of five operations, and the workpiece 8 having a complicated shape can be cut.

Also, the movable range of the plasma torch 7 can be moved to an arbitrary location in the pool A water by a combination of the above-described five operations in total, and the large structure within the range of the pool A can be cut. Is possible.

The mast 6 has a lower portion of the mast driving device 5 and a portion above the mast driving device 5 rotatably connected in a vertical direction by a hinge 15.

The hinge 15 is employed as a structure of a rotation mechanism for rotating at least a part of the mast 6. The mast 6 can be bent in the middle of the full length of the mast 6 by rotating at the hinge 15.

The hinge 15 is provided with a hinge stopper 22 capable of allowing or preventing rotation by the hinge 15.

As shown in FIG. 7, the hinge stopper 22 has a tubular shape, and includes a hinge 15 and a mast 6 above and below the hinge 15 inside the tubular shape.
A screw formed on the inner side of the cylinder is screwed into a screw formed on the mast 6 above and below the mast 6, and the lower part of the mast 6 above the hinge 15 rotates about the hinge 15. (Hereinafter simply referred to as the operation of fixing the hinge stopper 22).

In order to release the fixing and allow the mast 6 below the hinge 15 to rotate, the hinge stopper 22 is rotated to feed the screw downward as shown in FIG. Fall prevention projection 2 fixed to
7 (hereinafter simply referred to as hinge stopper 22).
It is called opening work. ).

In this manner, the mast 6 below the hinge 15 is rotated upward about the hinge 15 as shown in FIG. 7 so that the mast 6 is bent at the hinge 15.

The gas recovery hood 11 is fixedly mounted on the mast 6 below the hinge 15.

A gas recovery hose 18 is connected to the gas recovery hood 11 so as to communicate with the inside of the hood. The gas recovery hose 18 is connected so that the recovered gas can be sent from the gas recovery hood 11 to the gas processing system, and the gas is purified by the gas processing system.

The mast 6 is a gas recovery hood 1 as shown in FIG.
1, and the extended portion is bent at right angles in the horizontal direction and the vertical direction, so that the tip of the plasma torch 7 is located immediately below the center of the gas recovery hood 11.
The gas 14 can be reliably recovered.

The plasma torch 7 is mounted on an extension of the lower end of the mast 6 described above. In mounting the plasma torch 7, the vertical direction angle can be adjusted via the torch swing mechanism 10 described above.

When a cutting operation is performed in water using the plasma torch 7, gas 14 is generated as a secondary product. This is the gas or pool A released to generate plasma.
Of water generated by electrolysis of water.
Since the gas 14 rises by entraining the fine scum of the material 8 to be cut having a high radiation dose, when released into the air, the radiation dose equivalent of the worker increases. For this reason, a gas recovery hood 11 for recovering the gas 14 is provided above the plasma torch 7, and the gas 14 generated during the underwater cutting operation in the pool A is recovered and a gas recovery hose 18 is provided.
Through to the gas treatment system. In the gas treatment system, the sent gas is purified by passing it through a filter, a desalter, or the like.

As described above, in the first embodiment, a total of 5
The workpiece 8 in the pool A is shredded by controlling the position and orientation of the plasma torch 7 with a degree of freedom so that the workpiece 8 is easy to handle and does not require a large space at the disposal place when the workpiece 8 is discarded. Reduce the volume.

The gas 14 generated in the underwater cutting operation is surely collected by the gas collecting hood 11 in the water and near the gas generating source, that is, the place where the cutting operation is being performed, before spreading to the pool A water surface. Purification by gas processing system to reduce radiation exposure. Here, the plasma torch 7
When the maintenance of the plasma torch 7 is required due to exhaustion or malfunction of the plasma, the method of pulling the plasma torch 7 from the water of the pool A to the air above the water surface is schematically shown in FIGS.
Shown in

First, during the underwater cutting operation, the hinge stopper 22 is prevented from rotating at the hinge 15 by the fixing operation of the hinge stopper 22, and the mast 6 has a single rigidity from the upper part to the lower part. Since the plasma torch 7 is in a high state and is securely held at an accurate position without wobbling, the operation of opening the hinge stopper 22, that is, the operation of opening the hinge stopper 22 described above is performed.

When the hinge stopper 22 is opened, the hinge stopper 22 retreats below the hinge 15, so that the mast 6 below the hinge 15 can rotate around the hinge 15.

After this state, the hook suspended from the chain block 21 is hooked on the suspension ring 23 previously fixed to the mast 6 below the hinge 15. The chain block 21 is mounted on a jib crane 13 that is horizontally rotatably mounted on a support attached to the traveling vehicle 2 as indicated by an arrow B in FIG.

When the hinge stopper 22 and the suspension ring 23 are submerged in the water of the pool A, the mast 6 is raised in advance by the mast drive mechanism 5 to position the hinge stopper 22 and the suspension ring 23 above the water surface. Let it. As a result, the above-described work relating to the hinge stopper 22 and the suspension ring 23 does not have to be performed underwater, and the work can be performed quickly and easily.

After opening the hinge stopper 22 and hooking the hook of the chain block 21 to the suspension ring 23, the chain block 21 is operated to lift the mast 6 below the hinge 15 so as to lift it. .

By this pulling, the lower part of the mast 6 is turned around the hinge 15 in the upward direction, that is, in the direction of the hatched arrow in FIG.
Reaches the air above the water surface of pool A.

At the time of this lifting, the jib crane 13 is rotated horizontally so that an excessive force is not applied to the hinge 15 as much as possible, thereby preventing a force in a direction different from the rotation axis of the hinge 15 from being forcibly applied.

Thereafter, the maintenance of the plasma torch 7 is performed in the air, and after the maintenance of the plasma torch 7 is completed, the plasma torch 7 is placed in the water by the reverse procedure of lifting the plasma torch 7 in the air. Reconfigure.

That is, the chain block 21 of the jib crane 13 is operated to suspend the mast 6 below the hinge 15 together with the plasma torch 7 and rotate downward around the hinge 15 so that the mast 6 is rotated downward. The mast 6 is aligned with the mast 6 above the hinge 15.

Next, a fixing operation of the hinge stopper 22 is performed so that the mast 6 can exhibit high rigidity so as not to be swung at the hinge 15 portion. Further, the hook of the chain block 21 is removed from the suspension ring 23, and the position and posture of the plasma torch 7 are set again at the cutting start position. Thereafter, the cutting operation is performed subsequently.

As described above, the maintenance work of the plasma torch 7 can be performed in the air, and it contributes to the reduction of radiation exposure in a shorter time than underwater, and can be performed safely.

According to this embodiment, since the plasma torch 7 can be brought into the air from the water by bending the mast without raising the mast 6, the mast 6 can be raised and the plasma torch 7 can be aired. The plasma torch 7 can be maintained without any interference with the ceiling or the necessity of removing the ceiling, even when the plasma torch 7 is surrounded by a space with a low ceiling that cannot be brought.

The low ceiling space used here is a cover such as a vinyl tent that covers the entire cutting device above the pool A even though the underwater cutting operation is covered with water. This occurs when the work area is isolated so that the work influence is unlikely to spread to the surrounding environment.

In such an embodiment, when the plasma torch 7 is pulled into the air during maintenance, the gas recovery hood 11 is also pulled into the air.

In the process of recovering the gas containing the highly radioactive substance generated at the time of cutting, the gas recovery hood 11 adheres to the radioactive substance on a narrow portion or the like and becomes a high radiation dose source. Therefore, an operator who performs maintenance of the plasma torch 7
It is necessary to always work while receiving the radiation from the gas recovery hood 11, and there is a problem that the exposure dose to the worker increases.

A second embodiment in which the first embodiment is partially improved to solve such a problem will be described below.

In the second embodiment, since there are many parts common to the first embodiment, the parts which are not common are described below, and the common parts are the same as those in the first embodiment, and the description is omitted.

In FIG. 3, the mast 6 moves in a horizontal two-dimensional direction above the pool A by the traveling trolley 2 and the traversing trolley 4, and the mast drive mechanism 5 supported by the traversing trolley 4 raises and lowers and turns. Also do.

The mast 6 has a hood mast 6a vertically extending downward from the mast drive mechanism 5 that is continuous with the mast 6 protruding above the mast drive mechanism 5, and a hood mast 6a. And a torch mast 6b rotatably connected in the vertical direction via a hinge 15.

The part of the mast 6 protruding above the mast drive mechanism 5 and the part of the hood mast 6a vertically extending below the mast drive mechanism 5 that is continuous with the mast drive mechanism 5 are formed by a series of straight tubular structures. The inside hollow space of the tubular structure communicates with the inside of the gas recovery hood 11.
The gas recovery hood 11 is fixed and held on the food mast 6a.

At the upper end of the mast 6, a gas treatment system 1
A gas recovery hose 18 connected to the mast 6 is connected to communicate with the hollow space inside the mast.

As in the first embodiment, the gas treatment system 16 is a facility for purifying the gas 14 recovered by the gas recovery hood 11 by passing the gas 14 through a filter or a debasic base.

The connecting tool 12 shown in FIG. 8 is fixedly installed on the food mast 6a. The connecting tool 12 includes a food mast fixing portion 26 fixed to the food mast 6a,
A torch mast fixing cover 25 is attached to the hood mast fixing portion 26 so as to be freely rotatable horizontally, and an opening / closing lever 24 for connecting and disconnecting the torch mast fixing cover 25 to and from the hood mast fixing portion 26.

During the underwater cutting operation, the connecting tool 12 closes the torch mast fixing cover 25 from the state shown in FIG. 8 (c) as shown in FIG. 8 (b) and moves the opening / closing lever 24 horizontally. By moving the torch mast fixing cover 25 vertically downward from the state, the torch mast fixing cover 25 is prevented from being caught by the opening / closing lever 24 and opened. In this way, the torch mast fixing cover 25 and the torch mast 6b sandwiched between the torch mast fixing covers 25 are prevented from rotating around the hinge 15. Conversely, the opening / closing lever 24 is rotated to the horizontal position, and the opening / closing lever 24 and the torch mast fixing cover 25 are rotated.
Torch mast fixing cover 2
8C, the torch mast 6b can be opened in the direction of the hatched arrow as shown in FIG. 8C, and the torch mast 6b about the hinge 15 is allowed to rotate.

The suspension ring 23 is fixed to the torch mast 6b. Below the suspension ring 23, the torch mast 6b has a shape bent along the gas recovery hood 11, and the lower end of the torch mast 6b has the plasma torch 7 positioned just below the center of the gas recovery hood 11. It is supported by. The reason for holding the plasma torch 7 by bending the lower end portion of the torch mast 6b in this manner is the same as in the first embodiment in that the gas 14 generated during the underwater cutting operation is used.
Is to be able to be reliably collected.

The torch mast 6b has a gas collection hood 1
A television camera 28 is installed below the camera 1 so that a cutting work site by the plasma torch 7 can be imaged. The video equipment is installed so that the captured image can be displayed on a television screen placed at a place where the operator of the underwater cutting device engaged in the cutting work can see.

The operator controls the position and posture of the plasma torch 7 by operating the underwater cutting device while watching the television screen, and performs a cutting operation.

In the second embodiment, the cutting operation is performed in the same manner as in the first embodiment by submerging the workpiece, the plasma torch 7 and the gas recovery hood 11 in the water in the pool A.

During the cutting operation, the connecting tool 12 connects the hood mast 6a and the torch mast 6b to rotate the torch mast 6b about the hinge 15 as shown in FIGS. 8 (a) and 8 (b). Stop so that the plasma torch 7 does not shake.

When the food mast 6a and the torch mast 6b are connected as described above, if the mast 6 is moved up and down or turned by the mast drive mechanism 5, the movement is transmitted to the food mast 6a and the torch mast 6b, and the movement is transmitted to the food mast 6b. 6a
And the torch mast 6b can perform the same movement, and the plasma torch 7 can control the movement with a total of five degrees of freedom as in the first embodiment.

The gas 14 generated by the underwater cutting operation is not spread on the way to the surface, but is not spread.
1 captured and collected.

During the cutting operation, the hood mast 6a and the torch mast 6b are moved integrally by the connecting tool 12. For this reason, even when the plasma torch 7 is horizontally moved, moved up and down, and turned, the gas recovery hood 11 always keeps the plasma torch 7
, And gas generated at the time of cutting can be efficiently collected.

The captured and collected gas 14 passes from the gas recovery hood 11 through the inner hollow portion of the food mast 6a and the inner hollow portion of the mast 6, passes through the gas recovery hose 18, and reaches the gas processing system 16, where the gas is processed. Purified in system 16.

When the maintenance of the plasma torch 7 is performed, first, the masts 6, 6a and 6b are driven until the hinge 15, the connecting tool 12 and the suspension ring 23 are located above the water surface of the pool A. The ascending drive is performed by the mechanism 5.

Next, the torch mast fixing cover 25 is opened by operating the opening / closing lever 24 of the connecting tool 12 as shown in FIG. 8C, and the torch mast 6a is moved in the direction of the hatched arrow in FIG. 8C. Make it open.

Next, the hook of the chain block 21 of the jib crane 13 is hooked on the suspension ring 23, and the torch mast 6 a is pulled up together with the plasma torch 7 by operating the chain block 21.

In this manner, the torch mast 6a rotates around the hinge 15 in the upward direction of the hatched arrow in FIG.

As described above, when it becomes necessary to replace the main body or the consumable part of the plasma torch 7 due to the occurrence of wear or a defect, the hood mast 6a and the torch mast 6b are separated by opening the connecting member 12, and the plasma torch is opened. The jig crane 13 lifts the torch mast 6 and the torch mast 6b into the air, so that the maintenance work of the plasma torch 7 can be performed in the air.

During the maintenance work, the gas recovery hood 11, which is a high radiation dose source, is always placed in the water of the pool A, and the water functions as a radiation shielding material. Is reduced.

As shown in FIG. 4, the entire mast 6 including the hood mast 6a is formed into a tubular structure and the inside is formed into a hollow structure, and the hollow structure is used as a passage for the recovered gas from the gas recovery hood 11 to the gas recovery hose 18. , Gas 14 and a holding mechanism for the gas recovery hood 11.

Therefore, as shown in FIG. 1, the gas recovery hose 18 does not meander near the water surface level of the pool A to generate a curved portion (curved path).

In the case of FIG. 1, when a large amount of the gas 14 is generated, there is a concern that the gas 14 is drawn into the gas recovery hose 18 while entraining the water of the pool A. In the case of FIG. 1, when the gas recovery hose 18 is long and curved due to the allowance of the mast 6 for turning or vertical and horizontal movement strokes, the water of the pool A accumulates in the curved portion and is collected in that portion. When the exhausted gas passes, pulsation occurs in the entire gas recovery hose 18, and the gas recovery hood 11, the mast 6, and the plasma torch 7 to which the gas recovery hose 18 is fixed vibrate. For this reason, high-precision cutting becomes impossible, and in some cases, cutting failure and damage to the plasma torch 7 are caused.

However, in the case of the second embodiment, pool A
The underwater and near-water gas passages are in a vertical food mast 6a. Therefore, the pool A where water is easily sucked
At a position close to the water surface, the hood mast 6a also serving as a gas recovery hose provides a straight metal pipe as a vertical gas passage without a curved portion, so that the water of the pool A caught therein does not accumulate but falls and vibrates. Not a source.

Since the water of the pool A does not accumulate in the food mast 6a, there is little possibility that the radioactive substance adheres and stays in the food mast 6a or the mast 6.
The radioactive substance adhering to a is washed away by the washing / removing device.

The washing / removing device receives the high-pressure water supply hose 20 shown in FIG. 5 through which the high-pressure water generating equipment and the high-pressure water supplied from the equipment pass, and receives the high-pressure water from the high-pressure water supply hose 20 to perform the high-pressure water supply. And a spray nozzle 19 for discharging spray water.

As shown in FIG. 5, the spray nozzle 19 is attached to a closing plate 17 for closing the upper end of the mast 6 together with a high-pressure water supply hose 20, and the direction of the spray nozzle 19 is moved up and down, left and right. The high radiation dose attached to the inner wall of the mast 6 is washed and removed.

Since the upper end of the mast 6 is closed by the closing plate 17, the decontaminated water falls without flowing backward and flows down into the pool A.

As described above, the radiation exposure of the worker can be reduced by preventing the adherence of the radioactive substance by washing the underwater cutting device.

In the second embodiment, similarly to the first embodiment, when the maintenance work of the plasma torch 7 is completed, the chain block 21 is operated to lower the torch mast 6b. By doing so, the torch mast 6b is connected to the hinge 15
Is rotated downward about the rotation center, and finally, FIG.
8C, the torch mast fixing cover 25 is closed by closing the torch mast fixing cover 25 and lowering the opening / closing lever 24 downward as shown in FIG. 8B. It is fixed so that it does not open in the position

As described above, the torch mast 6b as the holding mechanism for the plasma torch 7 is fixed to the food mast 6a as the holding mechanism for the gas recovery hood 11, and the plasma torch 7 is reset in the pool A water.

[0100]

According to the first aspect of the present invention, maintenance of the cutting actuator of the submerged cutting device can be performed easily and quickly.

According to the invention of claim 2, in addition to the effect of the invention of claim 1, during maintenance of the cutting actuator, the cutting actuator is pulled up into the air while the gas recovery hood remains in the liquid, and the maintenance work is performed. At this time, since the gas recovery hood, which is a radiation dose, can be kept in the liquid, the effect of reducing the radiation exposure of the maintenance worker is increased.

According to the third aspect of the present invention, in addition to the effect of the second aspect of the present invention, the gas discharge passage can be used also as another structure having no curved portion, so that the gas discharge passage is exposed to a radiation environment. The amount of components to be contaminated by the radiation material can be reduced by reducing the amount of components to be cut, and the effect of reducing the cause of vibration generation that affects cutting accuracy can be obtained.

According to the invention of claim 4, in addition to the effect of the invention of claim 3, since the radioactive substance can be removed from the exhaust passage by cleaning the gas exhaust passage from the gas recovery hood, maintenance personnel and the like can use the gas exhaust passage. The radiation exposure reduction effect of the personnel approaching the submerged cutting device and the radiation exposure reduction effect of the submerged cutting device itself can be exhibited.

[Brief description of the drawings]

FIG. 1 is an overall view of an underwater cutting device according to a first embodiment of the present invention.

FIG. 2 is a side view of the underwater cutting device of FIG. 1;

FIG. 3 is an overall view of an underwater cutting device according to a second embodiment of the present invention.

FIG. 4 is a view schematically showing an exhaust passage of a recovered gas to a gas processing system in the underwater cutting device of FIG. 3;

5 is a view of a mast portion when the underwater cutting device of FIG. 3 is equipped with a cleaning device, and FIG.
FIG. 2B is an enlarged sectional view of a portion c in FIG.

6 is an overall view of the underwater cutting device showing a state in which the mast in FIG. 1 is pulled up.

FIG. 7 is a view of the vicinity of the hinge showing the handling of the hinge stopper in the procedure up to raising the mast of FIG. 1,
(A) is a view showing a state in which the hinge cannot move the hinge stopper, and (b) is a view showing a state after the pulling up is started.

FIG. 8 is an explanatory view of the connecting tool in FIG. 3;
The figure is an elevational view of a state in which the torch mast and the food mast are fixed with a connector, (b) is a cross-sectional view taken along the line AA in (a), (c) is a view in FIG. It is sectional drawing of the state which released the fixation with the connection tool with a food mast.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Running rail, 2 ... Running trolley, 3 ... Traversing rail, 4 ...
Horizontal trolley, 5: mast drive mechanism, 6: mast, 6a: food mast, 6b: torch mast, 7: plasma torch, 8: material to be cut, 9: main arc, 10: torch swing mechanism, 11: gas recovery hood , 12 ... Connector, 13
... Jib crane, 14 ... gas, 15 ... hinge, 16 ... gas treatment system, 17 ... close plate, 18 ... gas recovery hose, 19 ... spray nozzle, 20 ... high pressure water supply hose,
21: Chain block, 22: Hinge stopper, 2
Reference numeral 3 represents a suspension ring, 24 represents an opening / closing lever, 25 represents a torch mast fixing cover, 26 represents a hood mast fixing portion, 27 represents a fall prevention projection, and 28 represents a television camera.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI B23K 10/00 501 B23K 10/00 501A 37/02 37/02 B G21F 9/30 531 G21F 9/30 531J 531K (72) Inventor Takao Shimura Hitachi, Ltd., Hitachi Plant, 3-1-1, Sachimachi, Hitachi, Ibaraki Prefecture (72) Inventor Tatsuyuki 3-1-1, Sachimachi, Hitachi, Hitachi, Ibaraki, Japan Hitachi, Ltd. Hitachi Plant (56) Reference Reference JP-A-61-254895 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G21C 19/02 G21F 9/30

Claims (4)

(57) [Claims] 1. A traveling vehicle that straddles a liquid pool, a traversing vehicle that is mounted on the traveling vehicle and moves in a direction orthogonal to a direction in which the traveling vehicle moves, and that is mounted on the traversing vehicle and supports a cutting actuator. A submerged cutting device, comprising: a holding mechanism that performs a rotation; 2. A submerged cutting device according to claim 1, wherein a gas recovery hood for recovering gas generated at the time of cutting is supported by another holding mechanism different from the holding mechanism of the cutting actuator. 3. The gas discharge device according to claim 2, wherein the other holding mechanism is a tubular structure having a hollow cross section, and the inside of the hollow cross section is connected to a gas recovery hood, and the tubular structure is configured to receive gas from the gas recovery hood. Submerged cutting device that doubles as a discharge passage. 4. The method according to claim 3, wherein the tubular structure has a high height.
A switch connected to the pressurized water generation equipment via a high pressure water supply hose
Play nozzle, and means for cleaning the inside of the tubular structure
And it is submerged cutting device provided Te.