Dust collection hood

Abstract

In decontamination work involving radioactive materials, laser irradiation is used to efficiently collect debris and dust generated from the surface of structures being decontaminated. [Solution] This is a dust collection hood 10 provided in a laser decontamination device 1 that decontaminates a structure by irradiating the surface W of a component of the structure to be decontaminated with laser light L emitted from a mounted laser head 3. The dust collection hood 10 consists of a plurality of panels 11, one end of which is supported on the laser light emission side of the laser head 3, and it partitions and covers the irradiation range of the laser light L that is in close contact with the component surface W. An outside air introduction slit space S is formed on the open end side of the upper panel 11U, partitioned by an outside air introduction panel 20, which controls the outside air to generate a predetermined airflow and introduce it into the dust collection hood 10. The lower panel 11L is provided with an airflow discharge section 6 that sucks up and collects the generated cutting fragments and dust into an external dust collection device 8.

Description

Technical Field

[0001] The present invention relates to a dust collection hood, and more particularly to a dust collection hood used for efficiently collecting cutting pieces and dust of radioactive substances generated from the surface of a decontamination target structure by laser irradiation in a decontamination operation using a laser decontamination device.

Background Art

[0002] In the demolition of facilities such as nuclear reactors, reprocessing plants, and accelerators in accordance with the decommissioning measures of nuclear power facilities and radiation utilization facilities, various decontamination devices using laser light have been proposed as devices for reliably and efficiently decontaminating the main body of structures contaminated with radioactive isotopes (hereinafter abbreviated as RI), members generated by demolition, parts, etc.

[0003] The contamination removal device disclosed in Patent Document 1 includes an injection head that is rotatably supported on a base supported at the tip of a robot arm and emits laser light. By irradiating the laser toward the decontamination target object with the tip of the injection head, radioactive substances are peeled off from the decontamination target object. A suction hood having a substantially frustum-shaped cylindrical shape is attached to the tip of the injection head. This suction hood surrounds the optical path of the laser light emitted from the injection head, and a brush portion whose tip abuts against the decontamination target object is formed at the edge of the enlarged large-diameter opening side. A suction unit is connected to this suction hood, and RI peeled off from the decontamination target object by laser irradiation and released into the suction hood is collected into a dust collector.

[0004] Regarding the contamination removal device disclosed in this Patent Document 1, the applicant has the purpose of decontaminating the object, but considering the shape characteristics of the structures and members to be decontaminated, a laser decontamination device that can efficiently decontaminate the surface of concrete structures with many planar shapes and the members of steel plates and steel materials of steel structures has been proposed (Non-Patent Documents 1 and 2).

[0005] In the laser decontamination apparatus 50 disclosed in Non-Patent Documents 1 and 2, a dust collection hood 51, as shown in Figures 7 and 8, is employed as a component corresponding to the suction hood disclosed in Patent Document 1, in order to efficiently decontaminate the surface W of a structural member having a planar shape. As shown in both figures, this dust collection hood 51 is attached to the laser beam L irradiation side of the laser head 53, which is supported at the tip of a multi-joint robot arm 52. Its shape is a flattened truncated square pyramid with open ends at both ends, and the opening 54 on the laser head 53 side is partitioned by protective glass 55. As shown in Figure 8, the laser beam L emitted from the laser head 53 passes through the protective glass 55 and is irradiated towards the surface W of the structural member to be decontaminated in a predetermined scanning pattern, allowing the RI on the surface W to be cut and removed.

[0006] According to the laser decontamination apparatus 50 disclosed in Non-Patent Documents 1 and 2, the flat surface portion of the structure to be decontaminated can be divided into multiple decontamination areas, and each decontamination area can be efficiently and sequentially decontaminated while moving a trolley (not shown) on which the system is mounted. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2019-155340 [Non-patent literature]

[0008] [Non-Patent Document 1] Seiichiro Tanaka, et al., "Development of Remotely Operated Laser Decontamination Technology," [online], February 28, 2022, Ando Hazama Research Annual Report Vol. 9 2021, [Retrieved September 20, 2024], Internet<https: / / www.ad-hzm.co.jp / trr / 2021 / jp / papers.html> [Non-Patent Document 2] Seiichiro Tanaka, et al., "Application of Laser Decontamination in the Decommissioning of RI Facilities," [online], February 29, 2024, Ando Hazama Research Annual Report Vol. 11 2023, [Retrieved September 20, 2024], Internet.<https: / / www.ad-hzm.co.jp / trr / 2023 / jp / papers.html> [Overview of the project] [Problems that the invention aims to solve]

[0009] Incidentally, in the laser decontamination apparatus 50 disclosed in Non-Patent Documents 1 and 2, the RI cuttings and generated dust removed from the surface of the structure to be decontaminated are sucked and collected by a dust collector 58 in the decontamination system through an airflow discharge pipe 56 and a dust collection pipe 57 connected to one end of the dust collection hood 51. At this time, there was a problem in that the generated dust adhered to the protective glass 55 that partitioned the opening 54 on the laser head 53 side, reducing the irradiation efficiency of the laser light L. As a countermeasure, an air supply pipe 61 is provided to supply compressed air from an external pressure source (compressor) 60 so as to surround the opening 54 on the laser head 53 side inside the dust collection hood 51, and compressed air is injected into the dust collection hood 51 from a nozzle 62 formed in the air supply pipe 61, thereby preventing dust from adhering to the protective glass 55 and ensuring the suction effect inside the dust collection hood 51 (Figure 8).

[0010] However, the dust collection hood 51 provided in the current laser decontamination device 50 does not provide sufficient airflow velocity for the air introduced from the outside air intake hole 59, and it was found that dust generated during cutting of the material surface W remained inside the dust collection hood 51 for a long time (Figure 5(b)). Furthermore, if compressed air is injected from the nozzle 62 of the air supply pipe 61 to eliminate contamination of the protective glass 55 and to ensure sufficient airflow velocity for the air introduced from the outside air intake hole 59 in order to reduce dust adhesion to the protective glass 55, the blower load of the dust collector 58 increases, which presents a problem as it necessitates the use of a larger device.

[0011] Therefore, the object of the present invention is to solve the problems of the conventional technology described above and to provide a dust collection hood that suppresses dust accumulation, reduces contamination of protective glass, and enhances dust collection efficiency in decontamination work using a laser decontamination device. [Means for solving the problem]

[0012] The dust collection hood of the present invention is provided in a laser decontamination device that decontaminates a structure to be decontaminated by irradiating the surface of the structure to be decontaminated with laser light emitted from a mounted laser head, and one end of the dust collection hood is supported on the laser light emission side of the laser head, and the other end, which is open, is in close contact with the surface of the structure to be decontaminated, and the irradiation range of the laser light is partitioned and covered by a plurality of panels, wherein a slit space is formed on the open end side of the upper panel of the panel, which controls outside air to generate a predetermined airflow and introduce it into the dust collection hood, and the lower panel of the panel is provided with an airflow discharge section which sucks up and collects cutting fragments and dust generated in the irradiation range of the laser light to an external dust collection device.

[0013] Preferably, the slit space is formed between the outside air intake panel, which is provided across the entire width of the open end of the upper panel, and the surface of the structure to be decontaminated.

[0014] The slit space preferably consists of a funnel slit closer to the outside air and a straightening slit communicating with the lower end of the funnel slit, and generates the predetermined airflow by passing it through the funnel slit and the straightening slit.

[0015] The aforementioned outside air intake panel preferably consists of an inclined panel that forms a funnel slit and a flat panel that forms a rectifying slit.

[0016] Preferably, the lower panel has a downward-pointing trapezoidal shape, and the airflow discharge section is provided at its lower end. [Effects of the Invention]

[0017] According to the present invention, an airflow with a sufficient speed is formed in the dust collection hood provided in the laser decontamination device, thereby suppressing the retention of dust in the dust collection hood, reducing the contamination of the protective glass, and enhancing the dust collection effect.

Brief Description of the Drawings

[0018] [Figure 1] Perspective view showing the rear configuration of the dust collection hood of the present invention and a part of the laser decontamination device (shown by phantom lines). [Figure 2] Explanatory view showing the dust collection hood shown in FIG. 1 and a part of the configuration of the laser decontamination device provided with the dust collection hood. [Figure 3] Perspective view showing the front configuration of the dust collection hood shown in FIG. 1. [Figure 4] Partial enlarged cross-sectional view of the outside air introduction panel and the outside air introduction slit space shown along the line IV-IV in FIG. 3. [Figure 5] Cross-sectional view schematically showing an example of the airflow state in the dust collection hood ((a) example according to the present invention, (b) example according to the conventional configuration). [Figure 6] Fluid analysis results by a two-dimensional model conducted to confirm the effect of the outside air introduction slit space provided in the dust collection hood of the present invention ((a) analysis results according to the present invention, (b) example of analysis results according to the conventional configuration). [Figure 7] Perspective view showing the rear configuration of the conventional dust collection hood and a part of the laser decontamination device (shown by phantom lines). [Figure 8] Explanatory view showing the dust collection hood shown in FIG. 7 and a part of the configuration of the laser decontamination device provided with the dust collection hood.

Embodiments for Carrying Out the Invention

[0019] Hereinafter, an embodiment of the configuration of the dust collection hood of the present invention provided in the laser decontamination device will be described with reference to the accompanying drawings.

[0020] Figure 1 shows a part of the laser decontamination apparatus 1 (shown by dashed lines) and the configuration of the dust collection hood 10 of the present invention provided on the laser decontamination apparatus 1 as seen from the rear. Figure 2 shows the dust collection hood 10 shown in Figure 1 and a part of the laser decontamination apparatus 1 equipped with the dust collection hood 10 as seen from the side. This laser decontamination apparatus 1 equipped with the dust collection hood 10 is a decontamination apparatus intended to decontaminate the surface (member surface W) of concrete and steel materials of structures contaminated with radioisotopes (RI) in dismantling work at nuclear facilities and radiation-utilizing facilities by remotely cutting away the laser beam in a thin layer.

[0021] As shown in Figures 1 and 2, this laser decontamination device 1 has a configuration almost identical to that of the conventional laser decontamination device 50 (Figures 7 and 8). It is supported at the tip of a multi-joint robot arm 2 that can be controlled to move to a predetermined position and includes a rectangular parallelepiped box-shaped laser head 3 that controlsly emits laser light L toward a predetermined target. The dust collection hood 10 of the present invention is supported on the laser light irradiation side of the laser head 3 via a connecting frame 3a. An opening 4 formed on the end face of the laser head 3 is covered with transparent protective glass 5. The laser light L emitted from the laser head 3 passes through the protective glass 5 and is irradiated toward the surface of the structure to be decontaminated (member surface W) in a predetermined scanning pattern within the space enclosed by the dust collection hood, allowing for the cutting and removal of RI from the member surface W. Cutting fragments and dust generated within the space enclosed by the dust collection hood are sucked up and collected by an external dust collection device (described later).

[0022] The dust collection hood 10 of the present invention is also composed of four panels 11 with a flattened truncated square pyramidal shape. The shape and dimensions of the top panel 11U and both side panels 11S are substantially the same as the main panel of the conventional dust collection hood 10 shown in Figures 7 and 8. Details of the shape of the bottom panel 11L will be described later. In this embodiment, the shape of the opening end of the dust collection hood 10 is a roughly square shape with sides of approximately 350 mm, and the end face shape on the laser head 3 side is also a roughly square shape with sides of approximately 250 mm, forming an opening 4 (approximately 160 mm square) through which the laser light passes. The vertical and horizontal dimensions and width (thickness) dimensions of the dust collection hood 10 are appropriately set according to the operating conditions such as the scanning pattern set in the laser decontamination device, the shape and dimensions of the surface of the components, and are not limited to the above values.

[0023] Furthermore, each panel (11S, 11L), excluding the top panel 11U, has a band-shaped flange 12 approximately 15 mm wide integrally formed on the peripheral edge that comes into contact with the structure to be decontaminated. During decontamination work, each flange 12 is brought into contact with the surface W of the member of the structure to be decontaminated, so that the opening end of the dust collection hood 10 is in close contact with the member surface W. To improve the contact with the member surface W, a cushioning material C such as a soft resin is attached to the contact surface of the flange 12.

[0024] (Configuration of the outside air intake slit space) A narrow outside air intake opening 13, as shown in Figures 3 and 4, is formed along the upper edge of the top panel 11U that is in contact with the member surface W, extending across the entire width of the top panel 11U. Furthermore, an outside air intake panel 20 is integrally formed along the upper edge of the top panel 11U on the opening side, so as to cover the entire width of this outside air intake opening 13, and to be continuous with the upper edge of the top panel 11U. As shown in Figures 3 and 4, the outside air intake panel 20 consists of a flat panel 21 whose lower edge is integrally continuous with the periphery of the outside air intake opening 13 of the top panel 11U, and an inclined panel 22 integrally formed on the upper part of the flat panel 21.

[0025] The outside air intake panel 20 forms an outside air intake slit space S (funnel slit 14, straightening slit 15) between itself and the surface W of the structural member to be decontaminated, allowing outside air to be introduced into the dust collection hood 10. The configuration and role of the outside air intake slit space S formed by the outside air intake panel 20 (inclined panel 22, flat panel 21) will be explained below with reference to Figures 4 and 5(a), following the flow of outside air introduced into the dust collection hood 10.

[0026] In the outside air intake slit space S, a funnel slit (funnel-shaped slit) 14 is formed in the space closest to the outside air, sandwiched between the member surface W and the inclined panel 22. This funnel slit 14 changes in cross-section so that it gradually narrows from the widened upper end 14a to the narrow lower end 14b, allowing outside air to be smoothly introduced into the dust collection hood 10. At this time, the inner surface 14c on the inclined side of the funnel slit 14 is inclined in a gently curved shape, as shown in Figure 4. Therefore, the airflow introduced from the upper end 14a of the slit is guided along the inner surface 14c of the inclined panel 22 to the lower end 14b of the slit. By reducing the cross-sectional area through which the airflow passes, the airflow velocity can be increased and the airflow can be guided to the straightening slit 15 that continues downwards.

[0027] Furthermore, a flow straightening slit 15 is formed in the space between the member surface W and the planar slit so as to be integrally connected with the funnel slit 14 in the vertical direction. The flow straightening slit 15 communicates with the lower end 14b of the funnel slit 14, and causes the airflow, whose velocity has increased after passing through the funnel slit 14, to pass further along the member surface W. The airflow passing through this flow straightening slit 15 becomes a downward unidirectional flow that flows as if being attracted to the member surface W due to the Coanda effect. In this way, in the present invention, by causing the airflow, which has been accelerated after passing through the funnel slit 14, to pass continuously through the flow straightening slit 15, a layered air curtain A that flows downward within the dust collection hood 10 along the member surface W can be formed (Figure 5(a)). By forming this air curtain A near the member surface W, it is possible to suppress the scattering of cutting chips and dust generated on the member surface W within the dust collection hood 10, and to prevent contamination of the protective glass 5 (Figure 1).

[0028] In this embodiment, the width D of the rectifying slit 15 (the distance between the member surface W and the upper panel 11U) is set to approximately 5 mm, and the height H is set to approximately 60 mm. The width D can be appropriately narrowed even during decontamination work by inserting a spacer (not shown) of a predetermined thickness in the width direction of the rectifying slit 15, thereby adjusting the flow velocity and flow rate of the airflow passing through the rectifying slit 15, and adjusting the thickness and range of the air curtain A (Figure 5(a)) formed inside the dust collection hood 10.

[0029] (Configuration of the airflow discharge side) In this invention, as shown in Figure 2, cuttings and dust generated during decontamination work in the area covered by the dust collection hood 10 are sucked and collected by the dust collector 8 via a series of devices that serve as airflow discharge sections connected to the lower panel 11L of the dust collection hood 10, such as the airflow discharge pipe 6 and the dust collection pipe 7. In this invention, the shape of the lower panel 11L is made into a roughly square pyramidal shape that is pointed downwards by joining four curved panels that are convex curved towards the inside of the hood, and the airflow discharge pipe 6 to which the dust collection pipe 7 is connected extends diagonally toward the dust collector 8. As a result, as shown in Figure 5(a), the airflow flowing along the four curved lower panel 11L can be efficiently guided to the airflow discharge pipe 6, and cuttings, dust, etc. generated inside the dust collection hood 10 can be efficiently collected by the dust collector 8 via the dust collection pipe 7.

[0030] (Results of airflow analysis using a 2D model) To confirm the effect of the outside air introduction slit space S (funnel slit 14, flow straightening slit 15) provided in the dust collection hood 10 of the present invention, a fluid analysis was performed using a two-dimensional model, and the pressure distribution results within the dust collection hood 10 were compared. Each figure in Figure 6 (Figure 6(a): present invention, Figure 6(b): conventional example) shows a two-dimensional fluid analysis model that models the dust collection hood region created by mimicking the configuration of the dust collection hood shown in each figure in Figure 5 (Figure 5(a): present invention, Figure 5(b): conventional example), and the outside air region of a predetermined range introduced into the dust collection hood region, along with the analysis results (numerical values). Each analysis model was created taking into account that differences in the element shape, boundary conditions, etc. of the outside air introduction slit space S affect the analysis results. For these analysis models, a suction flow of a predetermined volume (for example, 3.0 m) was applied to the dust collection side. 3 Analysis using input ( / min) revealed that the negative pressure within the dust collection hood area of ​​the present invention was -7.5kPa (Figure 6(a)), confirming that outside air can be drawn in at the same airflow rate with a smaller negative pressure than the set negative pressure within the dust collection hood area of ​​the conventional shape (-12.1kPa (Figure 6(b))).

[0031] In the above description, the dust collection hood of the present invention has been described in an embodiment in which it is provided on a laser decontamination device. However, the application is not limited to laser decontamination devices. For example, in conventional machine tools, when performing cutting operations such as thinly peeling off a predetermined area from the surface of a flat member, it can be used to cover the cutting work area in order to prevent scattering of cutting fragments to the surroundings and to efficiently collect the cutting fragments.

[0032] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are possible within the scope of each claim. In other words, embodiments obtained by combining technical means that have been appropriately modified within the scope of the claims are also included in the technical scope of the present invention. [Explanation of symbols]

[0033] 1.50 Laser decontamination equipment 3.53 Laser Head 4.54 openings 6.56 Airflow exhaust pipe 8.58 Dust collector 10.51 Dust collection hood 11U Top Panel 11S Side Panel 11L Bottom Panel 13. Opening for outside air intake 14 Funnel Slits 15. Rectification slits 20. Outdoor air intake panel 21 Flat Panels 22 Inclined Panels L laser light S Outside air intake slit space W member surface

Claims

1. It is equipped in a laser decontamination device that decontaminates structures by irradiating them with laser light emitted from a mounted laser head, A dust collection hood is provided, in which one end is supported on the laser beam emission side of the laser head, the other open end is in close contact with the surface of the structure to be decontaminated, and the irradiation range of the laser beam is partitioned and covered by a plurality of panels, A slit space is formed on the open end side of the upper panel of the aforementioned panel, which controls the outside air to generate a predetermined airflow and introduce it into the dust collection hood. A dust collection hood characterized in that the lower panel of the panel is provided with an airflow discharge section that sucks up and collects cutting fragments and dust generated within the irradiation range of the laser beam to an external dust collection device.

2. The dust collection hood according to claim 1, wherein the slit space is formed between the outside air intake panel, which is provided across the entire width of the open end of the upper panel, and the surface of the structure to be decontaminated.

3. The dust collection hood according to claim 1 or claim 2, wherein the slit space comprises a funnel slit closer to the outside air side and a straightening slit communicating with the lower end of the funnel slit, and the predetermined airflow is generated by passing the air through the funnel slit and the straightening slit.

4. The dust collection hood according to claim 2, wherein the outside air intake panel comprises an inclined panel that forms a funnel slit and a flat panel that forms a rectifying slit.

5. The dust collection hood according to claim 1, wherein the lower panel has a pyramidal trapezoidal shape that points downward, and the airflow discharge section is provided at the lower end.

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