JP2017159308A - Laser cutting device and laser cutting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laser cutting device that inhibits generation of bubbles containing fume in underwater laser cutting.SOLUTION: A laser cutting device 10 includes: a laser irradiation head 20 capable of irradiating with a laser beam Lb a cutting object position of a structure immersed into water Sa via a gas phase space Sb; a gas phase space formation part 21 for forming the gas phase space Sb between the cutting object position and the laser irradiation head 20; and a bubble miniaturization part 50 disposed upward from the cutting object position in the water Sa and dividing bubbles generated when cutting the structure with the laser beam Lb.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a laser cutting device and a laser cutting method.

  A method of laser cutting a metal structure such as a nuclear reactor is known. When laser cutting of a metal structure is performed, generation of fine metal particles called fume may be a problem. As means for suppressing such a problem, for example, Patent Document 1 discloses a laser cutting device that performs laser cutting in a state where a metal structure is submerged in water.

Japanese Patent No. 4575267

By the way, in order to perform laser cutting in water, it is necessary to perform a cutting operation while supplying a gas to a cutting portion of the metal structure to form a gas space. At this time, when the laser penetrates the metal structure, the gas in the gas space passes through the penetrating portion and becomes a bubble containing fumes. When such bubbles rise to the water surface at once, fumes are released to the atmosphere.
In the case of the laser cutting device of Patent Document 1, a recovery device for recovering fumes is provided, but when the laser penetrates the metal structure, bubbles containing fumes are also generated and the fumes are released to the atmosphere. .

  An object of the present invention is to provide a laser cutting device and a laser cutting method that suppress generation of bubbles containing fumes during underwater laser cutting.

  The laser cutting device according to the first aspect includes a laser irradiation unit capable of irradiating a laser on a cutting target position of a structure immersed in water through a gas phase space, and between the cutting target position and the laser irradiation unit. A gas phase space forming part for forming the gas phase space, and a bubble refinement that is arranged above the position to be cut in the water and divides the bubbles generated when the structure is cut by the laser A part.

  According to this aspect, the bubbles generated during underwater laser cutting are divided into small portions by the bubble refining unit. By dividing the bubbles into small pieces, the fumes contained in the bubbles can be dissolved in water, so that the generation of bubbles containing fumes can be suppressed.

  The laser cutting device according to the second aspect is the laser cutting device according to the first aspect, wherein the bubble refining unit includes a porous body, and the porous body includes a plurality of holes penetrating in a direction intersecting a horizontal plane.

  According to this aspect, the foam can be divided into small pieces by the porous body.

  The laser cutting device according to the third aspect is the laser cutting device according to the second aspect in which the porous bodies are arranged vertically.

  According to this aspect, the foam can be divided into a plurality of stages by arranging the porous bodies vertically.

  The laser cutting device according to a fourth aspect is the laser cutting device according to the third aspect, wherein the porous body is a plurality of porous bodies whose lower surfaces are inclined alternately with respect to a horizontal plane.

  According to this aspect, the plurality of porous bodies inclined alternately can be divided into a plurality of stages while meandering the bubbles.

  The laser cutting device according to the fifth aspect is the laser cutting device according to any one of the second to fourth aspects, further including a vibrating portion that vibrates the porous body.

  According to this aspect, the bubble dividing action in the porous body can be promoted by vibrating the porous body.

  The laser cutting device according to a sixth aspect is the laser cutting device according to any one of the first to fifth aspects, wherein the bubble refining unit includes a fin that extends in a direction intersecting with the rising direction of the bubble and rotates about an axis intersecting the intersecting direction. It is a laser cutting device of the aspect.

  According to this aspect, the bubbles can be divided into small portions by the rotation of the fins.

  A laser cutting apparatus according to a seventh aspect is the laser cutting apparatus according to any one of the first to fifth aspects, wherein the structure is a structure of a nuclear reactor.

  According to this aspect, the release of radioactive fumes can be suppressed.

  A laser cutting method according to an eighth aspect includes a laser irradiation unit installation step of installing a laser irradiation unit capable of irradiating a laser at a cutting target position of a structure immersed in water, the cutting target position, the laser irradiation unit, A gas phase space forming step for forming a gas phase space, and a bubble refining unit that divides bubbles generated when the structure is cut by the laser above the position to be cut in the water. And a foam refinement portion placement step to be placed.

  According to this aspect, the bubbles generated during underwater laser cutting are divided into small portions by the bubble refining unit. By dividing the bubbles into small pieces, the fumes contained in the bubbles can be dissolved in water, so that the generation of bubbles containing fumes can be suppressed.

  According to the laser cutting device and the laser cutting method of the present invention, generation of bubbles containing fumes can be suppressed during underwater laser cutting.

It is the schematic at the time of laser cutting apparatus installation in 1st embodiment which concerns on this invention. It is detail drawing at the time of laser cutting device installation in a first embodiment concerning the present invention. It is detail drawing at the time of laser cutting apparatus installation in 2nd embodiment which concerns on this invention. It is detail drawing at the time of laser cutting apparatus installation in 3rd embodiment which concerns on this invention. It is detail drawing at the time of laser cutting device installation in 4th embodiment concerning the present invention. It is detail drawing at the time of laser cutting device installation in 5th embodiment concerning the present invention. 3 is a flowchart of a laser cutting method according to the present invention.

  Hereinafter, various embodiments according to the present invention will be described with reference to the drawings.

"First embodiment"
A first embodiment of a laser cutting device according to the present invention will be described with reference to FIGS.

  FIG. 1 shows a state in which the laser cutting device 10 of the present embodiment is applied to a cutting operation of an in-core structure 91 inside a nuclear reactor vessel 90 of a nuclear power plant.

  The structure to be cut is immersed in water Sa. The laser cutting device 10 is installed on the structure immersed in the water Sa. In particular, the in-reactor structure 91 inside the reactor vessel 90 to be cut in this embodiment has radioactivity, so that it is filled with water Sa together with the pits P provided on the upper portion of the reactor vessel 90. Is installed. Therefore, the reactor internal structure 91 inside the nuclear reactor vessel 90 installed in the water Sa is cut as it is. That is, the laser cutting device 10 is installed as it is with respect to the in-reactor structure 91 inside the reactor vessel 90 installed by being immersed in water Sa.

  The laser cutting device 10 includes a laser irradiation head 20, a laser cutting device main body 30, and a bubble refinement unit 50. The laser cutting device 10 further includes a gas / high pressure water supply path 41, a wiring 42 including an optical fiber 42a, and a wiring 43.

The installation state of the laser irradiation head 20 will be described.
As shown in FIG. 1, the laser irradiation head 20 is installed at the position to be cut of the reactor internal structure 91 inside the reactor vessel 90. The laser irradiation head 20 is provided at the lower end of the support portion 29. The upper end of the support portion 29 is fixed so as to be able to support the laser irradiation head 20 facing the surface of the reactor internal structure 91 inside the reactor vessel 90 above the position to be cut. The laser irradiation head 20 is installed so as to face the cutting target position of the reactor internal structure 91 inside the reactor vessel 90 immersed in the water Sa by being supported by the support portion 29.

  Regarding the installation work of the laser irradiation head 20, the installation of the laser irradiation head 20 by an operator is often difficult because it is an underwater work or a work with a radioactive structure. When it is difficult for an operator to install the laser irradiation head 20, the laser irradiation head 20 may be installed by remote work or a robot.

  The laser irradiation head 20 installed so as to face the cutting target position irradiates the cutting target position with a laser beam from the surface of the in-reactor structure 91 inside the reactor vessel 90, and the in-reactor structure inside the reactor vessel 90. Cut 91.

The installation state of the bubble refinement | purification part 50 is demonstrated.
As shown in FIG. 1, the bubble refining unit 50 is installed in the reactor internal structure 91 inside the nuclear reactor vessel 90. In the case of FIG. 2 of the present embodiment, the bubble refinement unit 50 is installed on the side opposite to the side irradiated with the laser Lb with respect to the in-furnace structure 91.
The bubble refining unit 50 is provided at the lower end of the support unit 59. The upper end of the support part 59 is fixed above the cutting target position so as to support the bubble refinement part 50. The bubble refining unit 50 is installed above the position to be cut of the reactor internal structure 91 inside the reactor vessel 90 filled with water Sa by being supported by the support unit 59.

  The bubble refining unit 50 installed above the cutting target position is generated from the cutting target position of the in-reactor structure 91 inside the reactor vessel 90, which will be described in detail later, toward the back side of the cutting unit, and then floats. Refine the bubbles. In the case of this embodiment, the reactor internal structure 91 inside the reactor vessel 90 is installed deep in the water Sa, and has a certain distance to the water surface. The bubble refining unit 50 may be installed at any depth as long as the rising bubble can be refined.

  Similarly to the laser irradiation head 20, when it is difficult for an operator to install the bubble refining unit 50, the bubble refining unit 50 may be installed by remote work or a robot.

The installation state of the laser cutting device main body 30 will be described.
The laser cutting device main body 30 includes a laser oscillator 30a and a gas / high pressure water supply device 30b. In the present embodiment, the laser cutting device main body 30 is installed at the edge of the pit P. One end of each of the gas / high-pressure water supply path 41, the wiring 42 and the wiring 43 is connected to the laser cutting device main body 30.
The gas / high pressure water supply path 41 includes an atmospheric gas supply path 41a, a high pressure water supply path 41b, and an assist gas supply path 41c.
The gas / high pressure water supply device 30b supplies an atmospheric gas Aa described later to the atmospheric gas supply path 41a. The gas / high pressure water supply device 30b supplies high pressure water Ww, which will be described later, to the high pressure water supply path 41b. Further, the gas / high pressure water supply device 30b supplies an assist gas At, which will be described later, to the assist gas supply path 41c.

The other ends of the gas / high pressure water supply path 41 and the wiring 42 are connected to the laser irradiation head 20.
A control signal and a response signal are exchanged between the laser cutting device main body 30 and the laser irradiation head 20 by the wiring 42 as necessary. Further, the laser Lb oscillated by the laser oscillator 30 a of the laser cutting device main body 30 is transmitted to the laser irradiation head 20 through the optical fiber 42 a.

  The other end of the wiring 43 is connected to the bubble refinement unit 50. A control signal and a response signal are exchanged between the laser cutting device main body 30 and the bubble refining unit 50 through the wiring 43 as necessary. When there is no need to exchange control signals and response signals between the laser cutting device main body 30 and the bubble miniaturization unit 50, the wiring 43 may not be provided.

  FIG. 2 shows the cross section of the main part of the laser irradiation head 20 of the laser cutting device 10 and the details of the bubble refinement unit 50.

The structure of the laser irradiation head 20 will be described.
The laser irradiation head 20 is supported by the support portion 29 so as to face the cutting target position of the in-core structure 91 inside the reactor vessel 90 in which the head tip 20a is immersed in water Sa.
The laser Lb transmitted to the laser irradiation head 20 is guided to the head tip 20a (laser irradiation unit) of the laser irradiation head 20, and is to be cut by the in-reactor structure 91 inside the reactor vessel 90 immersed in water Sa. The position is irradiated.
The assist gas At is supplied from the gas / high pressure water supply device 30b to the laser irradiation head 20 through the assist gas supply path 41c. The assist gas At supplied to the laser irradiation head 20 is injected from the head tip 20a to the cutting target position of the in-furnace structure 91. The injected assist gas At promotes the cutting of the in-furnace structure 91 by the laser Lb by blowing off the in-furnace structure 91 melted by the laser Lb or reacting with the melted in-furnace structure 91. . Examples of the gas used as the assist gas At include argon, helium, nitrogen, oxygen, and the like.
Therefore, the in-furnace structure 91 is cut at the cutting target position by the irradiation of the laser Lb and the injection of the assist gas At.

The laser irradiation head 20 includes a cylindrical gas phase space forming unit 21 on the outer periphery.
The gas phase space forming unit 21 forms the cylindrical water wall Wab by injecting the supplied high-pressure water Ww from the cylindrical end toward the object to be cut.
Therefore, the gas phase space Sb is defined by the inner peripheral surface of the water wall Wab, the outer peripheral surface of the laser irradiation head 20, and the object to be cut.
Further, as shown in FIG. 2, the atmospheric gas Aa is supplied to the gas phase space Sb via the gas phase space forming unit 21.
That is, from the laser irradiation head 20 including the gas phase space forming unit 21, the wall Wab by the high-pressure water Ww and the gas Aa for forming the gas phase are supplied in the wall Wab in order to maintain the gas phase space Sb. .
Therefore, when the laser irradiation head 20 is installed at the cutting target position, the atmospheric gas Aa in the gas phase space Sb is held between the head tip 20a and the cutting target position.

Since the laser is usually scattered by water, if the space between the cutting target position and the laser head is filled with water, the laser will be scattered before reaching the cutting target position, so that the structure cannot be cut. . Therefore, the gas phase space forming unit 21 forms a gas phase space Sb filled with air at least between the laser irradiation head 20 and the position to be cut of the reactor internal structure 91 inside the reactor vessel 90.
The atmospheric gas Aa filling the gas phase space Sb is supplied from the gas / high pressure water supply device 30b to the laser irradiation head 20 via the atmospheric gas supply path 41a.
The high-pressure water Ww that holds the gas phase space Sb is supplied from the gas / high-pressure water supply device 30b to the laser irradiation head 20 via the high-pressure water supply path 41b. However, the high-pressure water Ww may be supplied by pressurizing and supplying the water Sa by providing a pump or the like in the water Sa.

The structure of the bubble refinement | purification part 50 is demonstrated.
The bubble miniaturization part 50 is a porous body provided with a plurality of holes penetrating between opposing surfaces. In particular, in the present embodiment, a net plate disposed on a horizontal plane is used as the porous body. The mesh plate has a mesh as a plurality of holes penetrating between the opposing surfaces.

  The diameters of the plurality of holes are formed corresponding to the sizes of the bubbles to be divided, which will be described in detail later. Specifically, if the diameter of the plurality of holes is equal to or larger than the size of the bubbles to be divided (the diameter of the horizontal surface of the bubbles when rising), the bubbles cannot be divided, and if the diameter is too small, the bubbles cannot pass. The diameter of the hole is formed to such an extent that the rising bubbles can be divided and passed.

  The bubble miniaturization part 50 is arrange | positioned so that a some hole may penetrate in the direction which cross | intersects a horizontal surface.

The operation of the laser cutting device 10 of this embodiment will be described.
The laser irradiation head 20 is installed at a position to be cut of the reactor internal structure 91 inside the reactor vessel 90. The laser irradiation head 20 irradiates the laser Lb, and the reactor internal structure 91 inside the reactor vessel 90 is cut. When the gas phase space Sb communicates with the rear surface of the laser irradiation surface at the position to be cut of the in-furnace structure 91 by laser cutting, the atmosphere gas Aa and the assist gas At filled in the gas phase space Sb are communicated via the communicating portion. , The in-furnace structure 91 is emitted to the side opposite to the side irradiated with the laser Lb. The emitted atmospheric gas Aa and assist gas At float as a plurality of bubbles Ba on the side opposite to the side irradiated with the laser Lb with respect to the in-furnace structure 91. The bubble Ba generated at the time of cutting includes fumes generated at the time of laser cutting.

  Since a laser is high energy, when a structure is cut using the laser, a fume containing many fine metal particles is likely to be generated. Furthermore, since the reactor internal structure 91 inside the nuclear reactor vessel 90 to be cut in the present embodiment has radioactivity, fumes with radioactivity are generated.

  Df in FIG. 2 indicates the rising direction of the bubble Ba. Foam-containing bubbles Ba coalesce with neighboring bubbles Ba in the ascent process, and rise while growing into larger-sized bubbles Ba.

  The bubble refining part 50 is installed between a bubble generation | occurrence | production location and the water surface of water Sa, and contacts the bubble Ba which floats in the middle of the floating process in the floating direction Df. Among the bubbles Ba in contact with the bubble refining unit 50, the bubbles Ba having a size larger than the plurality of holes of the bubble refining unit 50 are divided into two or more bubbles Bb when passing through the plurality of holes. . Therefore, the bubble Ba is divided into bubbles Bb having a smaller size than the bubble Ba by passing through the bubble refining unit 50. Further, by dividing the rising bubbles Ba, it is possible to suppress the growth of the rising bubbles as a whole. The divided bubbles Bb rise to the surface of the water Sa and are released into the atmosphere.

  The fumes contained in the bubbles Ba and the bubbles Bb are dissolved in the water Sa when ascending. The more fume melts, the more time it takes to float, the more it melts. Also, the amount of fumes that melt increases as the surface area of the bubbles increases.

  On the other hand, since the bubble Bb divided into two or more is smaller in size than the bubble Ba, the buoyancy received in the water Sa is small and the rising speed is slow. Moreover, since the bubble Bb is smaller in size than the bubble Ba, the ratio of the surface area to the volume is large.

  That is, it takes longer to reach the water surface due to a decrease in the rising speed of the bubbles, compared to the case where the bubbles Ba are left floating, and the bubbles are reduced in size. Can increase the ratio of the surface area of the foam to the volume of the foam.

  Therefore, it is possible to dissolve a lot of fumes in the water Sa by increasing the time until the bubbles reach the water surface and increasing the ratio of the surface area to the volume of the bubbles. If a large amount of fumes contained in the bubbles can be dissolved in the water Sa, generation of bubbles containing fumes can be suppressed during underwater laser cutting, and the release of fumes into the atmosphere can be suppressed.

  In particular, in the case of the present embodiment, radioactive fumes are generated. Therefore, according to the present embodiment, release of fumes having radioactivity can be suppressed, and radiation leakage to the atmosphere can be suppressed.

"Second embodiment"
A second embodiment of the laser cutting device according to the present invention will be described with reference to FIG.

  The laser cutting device 100 according to the present embodiment differs from the laser cutting device 10 according to the first embodiment in that a bubble refining unit 150 including a plurality of porous bodies is provided as a bubble refining unit. Others are the same as the laser cutting device 10 of the first embodiment.

The structure of the bubble refinement unit 150 will be described.
The bubble refining unit 150 includes a first porous body 151, a second porous body 152, and a third porous body 153. The 1st porous body 151, the 2nd porous body 152, and the 3rd porous body 153 are porous bodies provided with the several hole penetrated between the surfaces which oppose. Also in this embodiment, the net plate arrange | positioned in the horizontal surface is used as the 1st porous body 151, the 2nd porous body 152, and the 3rd porous body 153. FIG. The mesh plate has a mesh as a plurality of holes penetrating between the opposing surfaces.

  The first porous body 151, the second porous body 152, and the third porous body 153 are arranged side by side in order from the bottom to the top. That is, the second porous body 152 is provided in the flying direction Df of the first porous body 151, and the third porous body 153 is provided in the flying direction Df of the second porous body 152.

The first porous body 151, the second porous body 152, and the third porous body 153 are all installed such that a plurality of holes penetrates in a direction intersecting the horizontal plane.
In the present embodiment, the plurality of holes of the second porous body 152 are holes having a smaller diameter than the plurality of holes of the first porous body 151, and the plurality of holes of the third porous body 153 are the second It is a hole having a smaller diameter than the plurality of holes of the porous body 152.

The operation of this embodiment will be described.
The bubble refining unit 150 is installed between the bubble generation location and the surface of the water Sa, and comes into contact with the rising bubble Ba in the middle of the rising process in the rising direction Df. First, the bubble Ba comes into contact with the first porous body 151. Of the bubbles Ba in contact, the bubbles Ba having a size larger than the plurality of holes of the first porous body 151 are divided into two or more bubbles Bb when passing through the plurality of holes. Therefore, the bubble Ba is divided into bubbles Bb having a smaller size than the bubble Ba by passing through the plurality of holes of the first porous body 151. The divided bubbles Bb further float in the flying direction Df, and are divided into smaller sizes each time passing through the second porous body 152 and the third porous body 153, and float to the surface of the water Sa, Released into the atmosphere.

  Therefore, the bubbles Ba are divided into a smaller size by being divided in a plurality of stages as compared with the case of being divided in a single stage.

  If the bubbles of smaller size are divided, more fumes can be dissolved in the water Sa, so that the release of fumes during underwater laser cutting can be further suppressed.

  As described above, in the present embodiment, the plurality of holes of the second porous body 152 have a smaller diameter than the plurality of holes of the first porous body 151, and the plurality of holes of the third porous body 153 are The biporous body 152 has a smaller diameter than the plurality of holes. As a modification, the plurality of holes of the first porous body 151, the plurality of holes of the second porous body 152, and the plurality of holes of the third porous body 153 may have the same diameter. Even if the diameters are the same, if the bubbles grow large between the porous body and the porous body, the bubbles can be divided in a plurality of stages.

  In this embodiment, the 1st porous body 151, the 2nd porous body 152, and the 3rd porous body 153 are installed at intervals, and utilize effectively the space from a bubble generation | occurrence | production location to the water surface. ing. That is, since the bubbles can be divided by waiting for the growth of the bubbles due to rising by installing the spaces apart from each other, it is possible to divide the bubbles into finer bubbles over the space from the bubble generation location to the water surface.

"Third embodiment"
A third embodiment of the laser cutting device according to the present invention will be described with reference to FIG.

  Compared with the laser cutting device 100 of the second embodiment, the laser cutting device 200 of the present embodiment is a bubble refinement in which the lower surfaces of a plurality of porous bodies are alternately inclined with respect to the horizontal plane as a bubble refinement unit. The difference is that the portion 250 is provided. Others are the same as the laser cutting apparatus 100 of 2nd embodiment.

The structure of the bubble refinement part 250 will be described.
The bubble refining unit 250 includes a first inclined porous body 251, a second inclined porous body 252, and a third inclined porous body 253. The 1st inclination porous body 251, the 2nd inclination porous body 252 and the 3rd inclination porous body 253 are porous bodies provided with the several hole penetrated between the surfaces which oppose. Also in the present embodiment, nets are used as the first inclined porous body 251, the second inclined porous body 252, and the third inclined porous body 253.

  The first inclined porous body 251, the second inclined porous body 252 and the third inclined porous body 253 are arranged side by side in the flying direction Df. That is, the second inclined porous body 252 is provided in the flying direction Df of the first inclined porous body 251, and the third inclined porous body 253 is provided in the flying direction Df of the second inclined porous body 252.

  The first inclined porous body 251 is arranged at an angle θ with respect to the horizontal direction in a vertical plane parallel to the direction in which the laser Lb extends. The second inclined porous body 252 is disposed in a vertical plane parallel to the direction in which the laser Lb extends and is inclined at an angle θ (angle −θ) with respect to the horizontal direction in the opposite direction to the second inclined porous body 252. Yes. The third inclined porous body 253 is inclined at an angle θ with respect to the horizontal direction in the same direction as the first inclined porous body 251 (opposite direction to the second inclined porous body 252) in a vertical plane parallel to the extending direction of the laser Lb. It is arranged.

  Therefore, the first inclined porous body 251, the second inclined porous body 252 and the third inclined porous body 253 are arranged so as to be alternately inclined toward the flying direction Df. At this time, the plurality of holes of the first inclined porous body 251, the second inclined porous body 252, and the third inclined porous body 253 are formed so as to penetrate in a direction intersecting with the horizontal plane when inclined.

The operation of this embodiment will be described.
The bubble refining unit 250 is installed between the bubble generation location and the surface of the water Sa, and comes into contact with the rising bubble Ba in the middle of the rising process in the rising direction Df. First, the bubbles Ba are in contact with the first inclined porous body 251. The bubble Ba that has come into contact floats in an oblique direction along the lower surface of the inclined first inclined porous body 251. The bubble Ba passes through the plurality of holes of the first inclined porous body 251 while rising in an oblique direction. The bubble Ba having a size larger than the plurality of holes of the first inclined porous body 251 is divided into two or more bubbles Bb when passing through the plurality of holes. Similarly, the divided bubbles Bb are further divided while sequentially passing through the second inclined porous body 252 and the third porous body 153 that are alternately inclined. The bubbles Bb that pass through the second inclined porous body 252 and the third porous body 153 that are alternately inclined are divided into smaller sizes while meandering, float on the water surface of the water Sa, and discharged into the atmosphere.

  Therefore, in this embodiment, since the bubbles rise while meandering, it is possible to earn more time to reach the water surface than when the bubbles rise without meandering. If it is possible to earn more time to reach the water surface, more fumes can be dissolved in the water Sa, so that the release of fumes during underwater laser cutting can be further suppressed.

"Fourth embodiment"
A fourth embodiment of the laser cutting device according to the present invention will be described with reference to FIG.

  The laser cutting device 300 according to the present embodiment differs from the laser cutting device 10 according to the first embodiment in that a vibration unit 360 that vibrates the bubble refining unit 350 is provided. Others are the same as the laser cutting device 10 of the first embodiment.

The structure and operation of the bubble refining unit 350 and the vibrating unit 360 will be described.
The vibration unit 360 is connected to the bubble refining unit 350 and vibrates the bubble refining unit 350. In the present embodiment, the vibration part 360 vibrates the bubble refining part 350 in the vibration direction Db. The vibration direction Db is a direction in which the laser Lb extends.

  When the bubble Ba passes through the plurality of holes and the bubble refining unit 350 vibrates in the vibration direction Db, the bubble refining unit 350 gives a stimulus in the vibration direction Db to the bubble Ba passing through the plurality of holes. . Therefore, the vibration unit 360 promotes the bubble dividing action in the bubble refining unit 350.

  The vibration direction by the vibration unit 360 is not limited to the vibration direction Db, and may be any direction as long as it stimulates the bubbles. For example, vibration in the flying direction Df, vibration in any direction other than Db in the horizontal plane It doesn't matter.

  The frequency and the amplitude of the vibration may be any frequency and amplitude as long as the frequency and the amplitude can be given to the bubbles.

  Furthermore, you may apply the vibration part of this embodiment to a some porous body like 2nd embodiment or 3rd embodiment. In that case, a plurality of porous bodies may be provided with vibration portions having different vibration directions, vibration frequencies or amplitudes, and the plurality of porous bodies may be vibrated with different vibration directions, vibration frequencies or amplitudes.

"Fifth embodiment"
A fifth embodiment of the laser cutting device according to the present invention will be described with reference to FIG.

  The laser cutting device 400 according to the present embodiment differs from the laser cutting device 10 according to the first embodiment in that a rotating fin 450 is provided as a bubble refining unit. Others are the same as the laser cutting device 10 of the first embodiment.

The structure and operation of the fin 450 will be described.
The fin 450 extends in the crossing direction of the flying direction Df, and rotates around an axis that crosses the crossing direction. In particular, in the present embodiment, as shown in FIG. 6, the fin 450 rotates around a rotation axis that extends in the horizontal direction and is parallel to the flying direction Df. In the present embodiment, the center of the fin 450 is rotated about the rotation axis. However, the fin 450 may be eccentrically rotated about one side of the fin 450 as the rotation axis.

  When the bubble Ba passes through the rotation region of the fin 450, the bubble Ba colliding with the rotating fin 450 is cut by the fin 450 and divided into two or more bubbles Bb. Accordingly, the bubbles Ba are cut into the bubbles Bb having a smaller size than the bubbles Ba by being cut by the fins 450. Further, by dividing the rising bubbles Ba, it is possible to suppress the growth of the rising bubbles as a whole.

"Laser cutting method"
The laser cutting method according to the present invention will be described with reference to FIG.

As shown in FIG. 7, first, the laser irradiation head 20 is installed at a position to be cut of the reactor internal structure 91 inside the reactor vessel 90 immersed in water (S1: laser irradiation unit installation step). Next, high-pressure water Ww is supplied from the gas / high-pressure water supply device 30b to maintain the gas phase space Sb and the atmospheric gas Aa that fills the gas-phase space Sb, and between the laser irradiation head 20 and the cutting target position. Next, a gas phase space Sb is formed (S2: gas phase space forming step). Subsequently, with respect to the in-furnace structure 91, a bubble refining unit is installed on the side opposite to the side irradiated with the laser Lb and above the position to be cut (S3: bubble refining unit arranging step). The foam refinement section to be installed may be any foam refinement section of the above embodiment. Then, the laser Lb is irradiated from the laser irradiation head 20 to the cutting target position (S4: laser cutting step). When laser cutting proceeds in the laser cutting step S4, the gas phase space Sb communicates with the back surface of the laser irradiation surface at the position to be cut of the in-furnace structure 91, and the atmosphere gas Aa filled in the gas phase space Sb is communicated with the communicating portion. And is emitted to the side opposite to the side irradiated with the laser Lb with respect to the in-furnace structure 91. The released atmospheric gas Aa and assist gas At become bubbles Ba containing fumes, but the bubbles Ba are refined by the bubble refining section installed above the locations where the bubbles Ba are generated.
Therefore, since the fumes contained in the bubbles can be dissolved in the water Sa by dividing the bubbles into small pieces, the generation of bubbles containing fumes can be suppressed. If the bubbles are divided, more fumes can be dissolved in the water Sa, so that the release of fumes during underwater laser cutting can be further suppressed.

In this laser cutting method, the in-core structure 91 submerged in the water inside the reactor vessel 90 is cut as it is.
When a structure that is not in water is cut in water, the laser cutting method can be implemented by providing an immersion step (S0) in which the structure is immersed in water before the laser irradiation unit installation step.
The step of immersing the structure in water may be a step of immersing the structure in water, or immersing the structure in water by filling water in a container in which the structure is installed. It may be a process.
Further, the method of cutting the in-core structure 91 inside the reactor vessel 90 submerged in water as it is includes the cutting method of the in-core structure 91 ′ of FIG. That is, a method in which the structure that has been laser-cut underwater is moved to a pit P provided in the upper part of the reactor vessel 90 as in the reactor structure 91 ′, and then the cut structure is further finely cut. Is included.

  As mentioned above, although embodiment of this invention was explained in full detail with reference to drawings, the specific structure is not restricted to the said embodiment, The design change etc. of the range which does not deviate from the summary of this invention are included.

In the case of this embodiment, with respect to the structure to be cut, the bubbles released to the side opposite to the side irradiated with the laser Lb are miniaturized.
The refinement of bubbles in the present embodiment is not limited to the refinement of bubbles released to the side opposite to the side irradiated with the laser Lb, but also applied to the refinement of bubbles released to the side irradiated with the laser Lb. I do not care. In that case, a bubble refinement | miniaturization part will be installed in the side irradiated with laser Lb.
Further, bubble miniaturization is performed on both the side irradiated with the laser Lb and the side opposite to the side irradiated with the laser Lb, and on both the side irradiated with the laser Lb and the side opposite to the side irradiated with the laser Lb. A bubble refining unit may be installed. Moreover, you may install a bubble refinement | miniaturization part so that it may straddle on the opposite side to the side which irradiates the laser Lb, and the side which irradiates the laser Lb in the upper part of a structure.

  In the present embodiment, the laser cutting device main body 30 oscillates the laser, but may oscillate by the laser irradiation head 20. In that case, there is no need to provide the optical fiber 42a. Furthermore, when there is no need to exchange control signals and response signals between the laser cutting device body 30 and the laser irradiation head 20, the wiring 42 need not be provided. In this case, the laser cutting device main body 30 can be configured only by the gas / high pressure water supply device 30b.

  In this embodiment, the laser irradiation head 20 is supported by the support unit 29 and the bubble refining unit 50 is supported by the support unit 59. However, a support beam is provided above the reactor vessel 90, and the laser irradiation head is provided with the same support beam. 20 and the bubble refinement part 50 may be supported. When the laser irradiation head 20 and the bubble refining unit 50 are supported by the same support beam, if it is necessary to scan the cutting target position of the structure, the laser irradiation head 20 and the bubble refining can be performed by scanning the support beam. The parts 50 can be scanned together.

In the present embodiment, the support portion 29 is fixed above the pit P, but may be fixed to the wall surface of the reactor vessel 90 by a suction cup, a magnet, a screw, a hook, or the like. Furthermore, a rail and a rail traveling unit may be provided in the support unit 29, and the laser irradiation head 20 may be configured to scan the wall surface of the reactor vessel 90 vertically and horizontally.
In the present embodiment, the support portion 59 is similarly fixed above the pit, but may be fixed to the wall surface of the reactor vessel 90 by a suction cup, a magnet, a screw, a hook, or the like. Further, a rail and a rail traveling unit may be provided on the support unit 59, and the bubble refining unit 50 may be configured to scan the wall surface of the reactor vessel 90.
In that case, you may comprise so that the laser irradiation head 20 and the bubble refinement | purification part 50 may scan the wall surface of the reactor vessel 90 in response.

  Although the wall is constituted by the water wall Wab as in the present embodiment, when the surface of the structure to be cut has few irregularities, the wall of the mechanism member is provided instead of the water wall Wab, and the gas phase space Sb is formed. It may be formed.

  You may provide the bubble refinement | miniaturization part of each embodiment of this embodiment combining in one laser cutting device. For example, a plurality of fins 450 may be provided side by side in the depth direction, or a vibrating part may be provided in each of the first inclined porous body 251, the second inclined porous body 252, and the third inclined porous body 253. Further, the fin and the porous body may be provided side by side in the depth direction.

  The porous body of the present embodiment may be anything as long as it has a plurality of holes such as a porous plate and a mesh plate in addition to the mesh plate.

  In the present embodiment, air is supplied to the gas phase space Sb, but any gas may be used as long as it does not scatter the laser.

10: Laser cutting device 20: Laser irradiation head 20a: Head tip 21: Gas phase space forming unit 29: Support unit 30: Laser cutting device body 30a: Laser oscillator 30b: Gas / high pressure water supply device 41: Gas / high pressure water supply Channel 41a: Atmospheric gas supply channel 41b: High-pressure water supply channel 41c: Assist gas supply channel 42: Wiring 42a: Optical fiber 43: Wiring 50: Bubble refinement unit 59: Support unit 90: Reactor vessel 91: In-reactor structure 91 ′: In-furnace structure 100: Laser cutting device 150: Bubble refining unit 151: First porous body 152: Second porous body 153: Third porous body 200: Laser cutting device 250: Bubble refining unit 251: first inclined porous body 252: second inclined porous body 253: third inclined porous body 300: laser cutting device 350: bubble refining unit 360: vibrating unit 400: laser cutting device 450: fin A : Atmosphere Gas At: assist gas Ba: Foam Bb: Foam Db: vibration direction Df: flying direction Lb: Laser P: Pit Sa: Water Sb: vapor space Wab: water wall Ww: high pressure water theta: angle

Claims (8)

A laser irradiation unit capable of irradiating a laser to a cutting target position of a structure immersed in water through a gas phase space;
A gas phase space forming unit that forms the gas phase space between the cutting target position and the laser irradiation unit;
A laser cutting device comprising: a bubble refining unit that is disposed above the cutting target position in the water and divides bubbles generated when the structure is cut by the laser. The bubble refinement section includes a porous body,
The laser cutting device according to claim 1, wherein the porous body includes a plurality of holes penetrating in a direction intersecting a horizontal plane. The laser cutting device according to claim 2, wherein the porous bodies are arranged vertically. The laser cutting device according to claim 3, wherein the porous body is a plurality of porous bodies whose lower surfaces are alternately inclined with respect to a horizontal plane. The laser cutting device according to any one of claims 2 to 4, wherein the bubble refining unit further includes a vibrating unit that vibrates the porous body. The laser cutting device according to any one of claims 1 to 5, wherein the bubble refining unit includes a fin that extends in a direction intersecting with the rising direction of the bubble and that rotates about an axis that intersects the intersecting direction. The laser cutting device according to any one of claims 1 to 6, wherein the structure is a structure of a nuclear reactor. A laser irradiation unit installation step of installing a laser irradiation unit capable of irradiating a laser at a position to be cut of a structure immersed in water;
A gas phase space forming step for forming a gas phase space between the cutting target position and the laser irradiation unit;
A bubble refining portion disposing step of disposing a bubble refining portion that divides bubbles generated when the structure is cut by the laser above the position to be cut in the water.

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