Decontamination method, decontamination device, and decontamination system

Abstract

To provide a decontamination technique which can easily avoid the occurrence of a vitrification phenomenon without requiring continuous temperature measurement of a front surface part during the decontamination work and can easily avoid the occurrence of secondary contamination following removal of a contamination layer when removing a contamination layer by peeling and destroying the contamination layer of the front surface part of an inorganic structure like a concrete structure with irradiation of a laser beam.SOLUTION: A laser beam LB is irradiated downward by a laser gun 21 and simultaneously ultrasonic mists UM are sprayed obliquely downward by a spray nozzle 31 to the same position as the irradiation position. The ultrasonic mists UM cool a front surface part S by the evaporation heat generated in the time of evaporation when reaching the front surface part S, enter independent air bubbles CC and mixed air bubbles MC of a contamination layer before the occurrence of a vitrification phenomenon without melting of the front surface part S or even when a portion thereof melts, suddenly expand in the air bubbles CC, MC to generate a phreatic explosion-like phenomenon to peel and destroy the contamination layer, and discharge the contamination layer as contamination pieces PP.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a decontamination method, a decontamination device, and a decontamination system for removing a contaminated layer from an inorganic structure, such as a concrete structure, by irradiating it with a laser beam. [Background technology]

[0002] Laser processing technology, which uses a laser beam to rapidly heat the surface of a workpiece, is also used in material removal applications such as cutting, drilling, and surface layer removal. For example, when a concrete structure is used as the workpiece (object to be removed), the concrete contains many inorganic solid particles, such as silica (silicon dioxide), which are the main component of aggregates such as gravel and sand. When silica and other inorganic solid particles are heated and melted by laser beam irradiation and then rapidly cooled, they can undergo glass transition, resulting in a highly viscous, amorphous glass state (vitrification phenomenon). Even if this glassy portion is re-melted by irradiating it with a higher-power laser beam, there is a risk of further vitrification occurring in the re-melted portion or its surroundings. Therefore, it must be removed by mechanical means such as cutting or impact destruction.

[0003] Patent Document 1 discloses a decontamination technology that removes the radioactive contamination layer on the surface of radioactively contaminated concrete by irradiating it with a laser beam, and that sequentially performs the following steps to remove and recover the radioactive contamination layer on the surface of concrete: a laser irradiation process that melts the radioactive contamination layer by irradiating it with a laser beam; a high-pressure gas injection process that injects high-pressure gas into the melted contamination layer to cool it and pulverize it into contaminant powder; and a contaminant powder recovery process that recovers the contaminant powder.

[0004] According to the decontamination technology of Patent Document 1, secondary contamination can be easily avoided by collecting contaminant powder together with the sprayed gas. However, increasing the spray rate of high-pressure gas to promote the generation and collection of contaminant powder increases the cooling rate of the molten contaminated layer, making vitrification more likely to occur due to rapid cooling. Therefore, in Patent Document 1, it is necessary to devise a way to avoid rapid cooling of the molten contaminated layer due to the spraying of high-pressure gas and avoid the occurrence of vitrification, such as by setting a predetermined time difference between the laser irradiation process and the high-pressure gas spraying process to ease the timing of cooling the molten contaminated layer.

[0005] On the other hand, Patent Document 2 discloses a removal (cutting or crushing) technology that cuts or crushes concrete structures by irradiating them with a laser beam, in which cooling gas or liquid is sprayed while the output of the laser beam, etc. is controlled so that the temperature of the concrete surface caused by the laser beam irradiation is below the melting point.

[0006] According to the removal technology of Patent Document 2, the surface temperature due to irradiation with a laser beam is controlled below the melting point, preventing the concrete from melting and vitrification, eliminating the need to consider rapid cooling of the molten layer by injecting cooling gas or liquid. However, as described in Patent Document 2, controlling the surface temperature of the concrete below the melting point requires the installation of a radiation thermometer and a control unit that constantly analyzes the temperature measurement data and controls the output of the laser beam during the operation. Therefore, while this technique can be performed without delay in cutting (or crushing) removal, in which the entire thickness of a concrete structure is removed in one or several steps, in surface layer removal, where the surface layer is removed little by little over multiple steps and the surface temperature distribution, etc., constantly fluctuates, the time required for data analysis may result in delays in the execution of output control. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-116892 [Patent Document 2] Patent No. 4709599 Summary of the Invention [Problem to be solved by the invention]

[0008] The object of the present invention is to provide a decontamination technology (decontamination method, decontamination device, and decontamination system) that can easily avoid the occurrence of vitrification without requiring continuous temperature measurement of the surface during decontamination work when removing a contaminated layer by peeling off and destroying the contaminated layer on the surface of an inorganic structure such as a concrete structure using laser beam irradiation, and can also easily avoid the occurrence of secondary contamination that accompanies the removal of the contaminated layer.

[0009] In order to solve the above problems, the decontamination method of the present invention comprises: A method for decontaminating an inorganic structure that contains inorganic solid particles, has a large number of bubbles present therein, and has a contaminated layer at least on its surface that is contaminated with a contaminant, comprising: In a closed negative pressure space surrounding the surface portion, a laser beam is irradiated onto the surface portion, and simultaneously, the atomized or atomized liquid is sprayed. The inside of the bubbles located at least in the surface portion is rapidly heated by the laser beam and rapidly expands. It is characterized by being sprayed at the same location as the laser beam irradiation position, peeling off and destroying the contaminated layer and removing it.

[0010] In order to solve the above problems, a representative decontamination method of the present invention includes: It contains inorganic solid particles as aggregate and has many fine closed bubbles. or larger entrained bubbles A method for decontaminating a concrete structure having a contaminated layer at least on its surface, the method comprising: In a closed negative pressure space surrounding the surface portion, a laser beam is irradiated onto the surface portion, and simultaneously, the atomized or atomized liquid is sprayed. The inside of the bubbles located at least in the surface portion is rapidly heated by the laser beam and rapidly expands. It is characterized by being sprayed at the same location as the laser beam irradiation position, peeling off and destroying the contaminated layer and removing it.

[0011] In this way, atomized or atomized liquid (e.g., water) is sprayed simultaneously with the laser beam irradiation and at the same location as the irradiation position, and when the atomized or atomized liquid reaches the surface, the surface is cooled by the heat of vaporization generated during evaporation, thereby suppressing melting, and Inside the bubbles located on the surface The contaminated layer is peeled off and destroyed by expansion due to rapid heating. Therefore, the occurrence of vitrification can be easily avoided without constantly monitoring the surface temperature during decontamination work and controlling the output of the laser beam. In addition, the atomized or atomized liquid is vaporized and collected along with the peeled off or destroyed contaminated pieces, so the occurrence of secondary contamination can also be easily avoided.

[0012] In the present invention, "pollutants" refers to harmful substances in general, such as toxic substances, radioactive substances, bacteria, etc., that may contaminate the environment, such as the air, water, or soil, or that may harm the health of decontamination workers and surrounding residents. For example, in tunnels such as expressways and subways, the main contaminants are black soot, NOx dust, SOx dust, PM dust, dioxins, and other toxic substances. In nuclear power plants, nuclear fuel reprocessing plants, and their surrounding areas, the main contaminants are radioactive substances such as cesium and plutonium.

[0013] Here, "the same location as the irradiation position" in "spraying atomized or atomized liquid at the same location as the irradiation position of the laser beam" means "the focal position of the beam" in the case of a stationary laser beam, and is expressed as "the moving trajectory of the beam focal point" in the case of a moving laser beam. Note that for a laser beam that rotates on a circular orbit to amplify its output, it means "within the rotation diameter of the beam (e.g., 50 mm)," and for a laser beam that moves while rotating, it means "within the moving width of the beam (e.g., 50 mm)."

[0014] Furthermore, water is usually used as the "liquid," but it does not have to be pure water or distilled water; it can be ordinary tap water, well water, spring water, etc. As the "atomized or atomized liquid," "ultrasonic atomized water," or "ultrasonic mist," is recommended, as will be described later.

[0015] Regarding the peeling and destruction of the contaminated layer, specifically: The liquid sprayed onto the surface cools the surface heated by the laser beam (by the heat of vaporization generated when it evaporates) to prevent melting, and The particle size is smaller than the bubbles in the contaminated layer. The liquid that has entered the bubbles in the contaminated layer is rapidly heated by the laser beam, and expands rapidly within the bubbles (causing a small-scale steam explosion-like phenomenon) to peel off and destroy the contaminated layer.

[0016] In this way, the atomized or atomized liquid sprayed toward the surface cools the surface by the heat of vaporization, and penetrates into the bubbles in the contaminated layer without melting the surface, or even if it does melt partially, before the vitrification phenomenon occurs.The liquid then expands rapidly within the bubbles, causing a steam explosion-like phenomenon that peels off and destroys the contaminated layer, and is released as contaminated fragments.

[0017] Furthermore, the above-mentioned irradiation of the laser beam and the injection of the liquid are carried out continuously or intermittently in synchronization with each other at the same location on the contaminated layer (to break down the contaminated layer into fine contaminant pieces like sparklers and remove it).

[0018] This allows the peeling and destruction of the contaminated layer and the removal of contaminated fragments to be carried out continuously without interruption. When the laser beam irradiation and liquid injection are carried out intermittently, this includes cases where the laser operates in a pulsed manner and cases where the laser operates in a reciprocating manner. The laser beam may be either a CW laser that is continuously irradiated or a pulsed laser that is intermittently irradiated.

[0019] Incidentally, "concrete structures" include concrete pavements, concrete retaining walls, concrete buildings, concrete tunnels, etc. Also, "concrete" includes cement concrete, asphalt concrete, resin concrete, etc.

[0020] Furthermore, "inorganic structures" include, in addition to the above-mentioned "concrete structures", the following: Mortar walls, plaster walls, earth walls, brick walls, tile walls; Concrete block paving, asphalt block paving, brick paving, tile paving.

[0021] In the case of reinforced concrete construction or earthen walls with bamboo frames (bamboo latticework), the decontamination method of the present invention is applied to the concrete parts excluding the reinforcing bars and the plaster wall parts excluding the bamboo frames (bamboo latticework).

[0022] Furthermore, in order to solve the above problems, the decontamination apparatus of the present invention comprises: A decontamination device for an inorganic structure that contains inorganic solid particles, has a large number of bubbles present therein, and has a contaminated layer at least on its surface that is contaminated by a contaminant, a decontamination chamber to which a suction mechanism is connected and which forms a closed negative pressure space surrounding the surface portion; a laser irradiation mechanism that irradiates the surface portion with a laser beam; a liquid injection mechanism that injects atomized or atomized liquid onto the surface, In the decontamination chamber, the laser irradiation mechanism irradiates the surface with a laser beam, and at the same time, the liquid injection mechanism sprays the atomized or atomized liquid. The inside of the bubbles located at least in the surface portion is rapidly heated by the laser beam and rapidly expands. The laser beam is sprayed at the same location as the irradiation position, and the suction mechanism sucks and removes the peeled or destroyed contaminated layer.

[0023] In order to solve the above problems, a representative decontamination apparatus of the present invention is as follows: It contains inorganic solid particles as aggregate and has many fine closed bubbles. or larger entrained bubbles A decontamination device for a concrete structure having a contaminated layer at least on the surface of which is contaminated by a contaminant, a decontamination chamber to which a suction mechanism is connected and which forms a closed negative pressure space surrounding the surface portion; a laser irradiation mechanism that irradiates the surface portion with a laser beam; a liquid injection mechanism that injects atomized or atomized liquid onto the surface, In the decontamination chamber, the laser irradiation mechanism irradiates the surface with a laser beam, and at the same time, the liquid injection mechanism sprays the atomized or atomized liquid. The inside of the bubbles located at least in the surface portion is rapidly heated by the laser beam and rapidly expands.The laser beam is sprayed at the same location as the irradiation position, and the suction mechanism sucks and removes the peeled or destroyed contaminated layer.

[0024] In this way, the liquid injection mechanism injects atomized or atomized liquid (e.g., water) at the same location as the laser beam irradiation by the laser irradiation mechanism, and when the atomized or atomized liquid reaches the surface, the surface is cooled by the heat of vaporization generated during evaporation, thereby suppressing melting, and Inside the bubbles located on the surface The contaminated layer is peeled off and destroyed by expansion due to rapid heating. Therefore, the occurrence of vitrification can be easily avoided without constantly monitoring the surface temperature during decontamination work and controlling the output of the laser beam. In addition, the atomized or atomized liquid is vaporized and collected along with the peeled off or destroyed contaminated pieces, so the occurrence of secondary contamination can also be easily avoided.

[0025] An atomization mechanism is recommended as the liquid injection mechanism. Known atomization mechanisms include suction atomization, which utilizes the suction action of a negative pressure generator, and driven atomization, which is driven by a drive source other than the negative pressure generator. The former includes atomization, which utilizes capillary action to spray airflow onto liquid (water) drawn up in a spray-like manner, and acceleration mechanism types equipped with a venturi or diffuser. The latter includes ejector types that use a pressure pump or other device for acceleration, centrifugal types that use high-speed rotation for acceleration, and ultrasonic types that use ultrasonic vibration.

[0026] The suction mechanism includes a negative pressure pump (suction fan) for negatively suctioning contaminated air generated in the decontamination chamber, and a dust collector with a built-in air filter, which is located in the suction flow path of the negative pressure pump. This air filter includes a main filter located downstream of the suction flow path and composed of a high-performance air filter such as a HEPA filter or ULPA filter, and a pre-filter located upstream of the main filter in the suction flow path and composed of a coarse dust air filter.

[0027] A HEPA filter (high-efficiency particulate air filter) has a particle capture efficiency of 99.97% or more for particles with a diameter of 0.3 μm at the rated flow rate, while a ULPA filter (ultra-low penetration air filter) has a particle capture efficiency of 99.9995% or more for particles with a diameter of 0.15 μm at the rated flow rate. Filters with a particle capture efficiency of 99.9999% or more are sometimes called ultra-ULPA filters. Coarse particle air filters are primarily used to remove particles larger than 5 μm. Furthermore, an intermediate filter, such as a medium-efficiency particulate air filter (i.e., an air filter with a moderate particle capture efficiency for particles smaller than 5 μm), may be added between the main filter and prefilter. These air filters comply with JIS Z8122 "Terminology for Contamination Control."

[0028] The liquid injection mechanism injects mist whose particle size is smaller than that of the air bubbles in the contaminated layer by ultrasonic atomization.

[0029] Concrete structures are made by solidifying aggregates, which make up the majority of the volume, with binders such as cement, asphalt, resin, etc. Coarse aggregates of approximately 5 mm or larger, such as gravel and crushed stone, and fine aggregates of less than 5 mm, such as sand and crushed sand, are used as aggregates.

[0030] Furthermore, within concrete structures there exist relatively large mixed cells (for example, 0.1 mm or larger) that are trapped when the binder and water are mixed, and fine closed cells (for example, 0.01 to 0.1 mm, average 0.05 mm) that are generated by the air-entraining agent (AE agent) added as an admixture.

[0031] On the other hand, the particle size of the mist generated by ultrasonic atomization (ultrasonic mist) is generally said to be around 0.001 to 0.01 mm (average 0.005 mm). Therefore, the particle size of ultrasonic mist can be made smaller than the closed bubbles present in concrete structures.

[0032] The laser beam irradiation destroys the surface, opening up isolated and entrained bubbles, and the ultrasonic mist that is sprayed enters these bubbles one after another, where it is rapidly heated by the laser beam, expanding rapidly within the bubbles and causing a small-scale steam explosion-like phenomenon that peels and destroys the contaminated layer one after another, generating tiny pieces of contaminant.In this way, the use of ultrasonic mist allows for smooth peeling and destruction of the contaminated layer and removal of the contaminated pieces.

[0033] the laser irradiation mechanism is provided with a single lens or a combination of lenses for irradiating a laser beam, and a gas injection mechanism for blowing air onto an objective lens surface, which is a lens surface facing the surface of the lens closest to the surface of these lenses; The gas injection mechanism constantly blows air toward the objective lens surface while the laser irradiation mechanism is in operation.

[0034] In this way, the gas blown from the gas injection mechanism prevents contaminant fragments peeled off or destroyed from the contaminant layer on the surface from coming into contact (colliding) with the objective lens surface of the laser irradiation mechanism, thereby contributing to a longer lifespan of the laser irradiation mechanism.

[0035] Although air is generally used as the gas blown from the gas injection mechanism, an inert gas (i.e., rare gas (helium, neon, argon, krypton, xenon, radon), nitrogen gas, carbon dioxide gas, etc.) can be used instead of or in addition to air. Also, a portion of the gas blown from the gas injection mechanism may be introduced into the liquid injection mechanism, and the atomized or atomized liquid (e.g., ultrasonic mist) sprayed from the liquid injection mechanism may be accelerated by the blown gas (e.g., air).

[0036] In order to solve the above problems, the decontamination system of the present invention comprises: A decontamination system for an inorganic structure that contains inorganic solid particles, has a large number of bubbles present therein, and has a contaminated layer at least on its surface that is contaminated by a contaminant, a decontamination chamber to which a suction mechanism is connected and which forms a closed negative pressure space surrounding the surface portion; a laser irradiation mechanism that irradiates the surface portion with a laser beam; a liquid injection mechanism that injects atomized or atomized liquid onto the surface; a control unit that issues control signals to the laser irradiation mechanism and the liquid ejection mechanism, The control unit controls the laser irradiation mechanism to irradiate the surface portion with a laser beam in the decontamination chamber, and the liquid injection mechanism to spray the atomized or atomized liquid. The inside of the bubbles located at least in the surface portion is rapidly heated by the laser beam and rapidly expands. The device is characterized by issuing a control signal so that the laser beam is sprayed at the same location as the irradiation position, and the suction mechanism sucks and removes the peeled or destroyed contaminated layer.

[0037] In order to solve the above problems, a representative decontamination system of the present invention comprises: It contains inorganic solid particles as aggregate and has many fine closed bubbles. or larger entrained bubbles A decontamination system for a concrete structure having a contaminated layer at least on the surface of which is contaminated by a contaminant, a decontamination chamber to which a suction mechanism is connected and which forms a closed negative pressure space surrounding the surface portion; a laser irradiation mechanism that irradiates the surface portion with a laser beam; a liquid injection mechanism that injects atomized or atomized liquid onto the surface; a control unit that issues control signals to the laser irradiation mechanism and the liquid ejection mechanism, The control unit controls the laser irradiation mechanism to irradiate the surface portion with a laser beam in the decontamination chamber, and the liquid injection mechanism to spray the atomized or atomized liquid. The inside of the bubbles located at least in the surface portion is rapidly heated by the laser beam and rapidly expands.The device is characterized by issuing a control signal so that the laser beam is sprayed at the same location as the irradiation position, and the suction mechanism sucks and removes the peeled or destroyed contaminated layer.

[0038] In this way, the liquid injection mechanism injects atomized or atomized liquid (e.g., water) at the same location as the laser beam irradiation by the laser irradiation mechanism, and when the atomized or atomized liquid reaches the surface, the surface is cooled by the heat of vaporization generated during evaporation, thereby suppressing melting, and Inside the bubbles located on the surface The control unit issues a control signal so that the contaminated layer is peeled off and destroyed by expansion due to rapid heating. Therefore, the occurrence of vitrification can be easily avoided without constantly monitoring the surface temperature during decontamination work and controlling the output of the laser beam. In addition, the atomized or atomized liquid is vaporized and collected along with the peeled off or destroyed contaminated pieces, so the occurrence of secondary contamination can be easily avoided.

[0039] The system further includes a moving device (e.g., a mobile work vehicle or a high-altitude work vehicle) that mounts or tows the above-mentioned decontamination chamber, laser irradiation mechanism, liquid injection mechanism, and control unit, and that can change the position of all of them relative to the surface in the work area to be decontaminated in response to a control signal issued from the control unit.

[0040] This makes it possible to automate decontamination work in open work areas by automatically driving the work vehicle using a control signal. It is also possible to automate only the decontamination work while the worker drives the work vehicle.

[0041] The decontamination chamber, the laser irradiation mechanism, and the liquid injection mechanism are mounted, and a moving device (for example, a mobile work platform with a robot arm) is further provided which can change the position of the decontamination chamber, the laser irradiation mechanism, and the liquid injection mechanism all at once in the work area to be decontaminated relative to the surface portion, The control unit is located at a predetermined position outside the work area, The moving device changes the positions of the decontamination chamber, the laser irradiation mechanism, and the liquid injection mechanism within the work area in response to control signals issued based on remote control by the control unit.

[0042] This makes it possible to fully automate the entire decontamination process, including the movement of robotic arms and mobile work carts, based on control signals when decontamination work is carried out in a closed work area, while workers monitor the work from a safe control unit (external control room) outside the work area. [Brief explanation of the drawings]

[0043] [Figure 1] FIG. 1 is an explanatory diagram schematically illustrating an example of a decontamination apparatus according to the present invention. [Figure 2] FIG. 2 is an explanatory diagram showing the concept of the decontamination method according to the present invention in the main part of FIG. [Figure 3] 1 is an explanatory diagram showing a schematic diagram of a decontamination system for an open road surface work area as a first example of a decontamination system according to the present invention. FIG. [Figure 4] Process diagram based on the decontamination system of Figure 3. [Figure 5] FIG. 10 is an explanatory diagram showing a decontamination system for an open-wall work area as a second example of a decontamination system according to the present invention. [Figure 6] A process diagram based on the decontamination system of Figure 5. [Figure 7] FIG. 10 is an explanatory diagram showing a schematic diagram of a decontamination system for a closed work area inside a building as a third example of a decontamination system according to the present invention. [Figure 8] FIG. 8 is a process diagram based on the decontamination system of FIG. 7. [Figure 9] FIG. 10 is an explanatory diagram showing a schematic diagram of a decontamination system for a closed working area in a tunnel as a fourth example of a decontamination system according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0044] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic diagram illustrating an example of a decontamination apparatus according to the present invention. The decontamination apparatus 100 shown in FIG. 1 decontaminates a massive concrete structure CS placed on a mounting table B. The decontamination apparatus 100 includes a decontamination booth 10 (decontamination chamber) connected to a suction mechanism 40 and forming a closed negative-pressure space surrounding the entire concrete structure CS, a laser irradiation mechanism 20 that irradiates a laser beam LB onto a surface portion S (see FIG. 2) of the concrete structure CS, and a water injection mechanism 30 (liquid injection mechanism) that sprays ultrasonically atomized ultrasonic mist UM onto the surface portion S. Note that while the mounting table B is shown fixedly positioned on the ground in FIG. 1, it may be movable on the ground in the left-right direction (direction of the arrow) of the figure, a direction perpendicular to the plane of the drawing, or the like.

[0045] As shown in Figure 2, the concrete structure CS occupies a large portion (e.g., 70%) of its volume. It consists of aggregates CA and FA, inorganic solid particles, solidified with binders such as cement, asphalt, and resin. The aggregates consist of coarse aggregate CA, consisting of gravel and crushed stone, approximately 5 mm or larger, and fine aggregate FA, consisting of sand and crushed sand, approximately 5 mm or smaller. The concrete structure CS contains relatively large entrained air bubbles MC, e.g., 0.1 mm or larger, and numerous fine closed air bubbles CC, e.g., 0.01–0.1 mm, with an average of 0.05 mm. The entrained air bubbles MC are air bubbles trapped during the mixing of binder and water, while the closed air bubbles CC are generated by air-entraining agents (AE agents) added as admixtures. In a concrete structure CS (e.g., radioactive waste generated at a nuclear power plant), at least the surface portion S forms a contaminated layer (e.g., a radioactively contaminated layer) contaminated by contaminants (e.g., radioactive materials).

[0046] Returning to FIG. 1, the decontamination booth 10 has a frame 11 that completely covers the concrete structure CS from above like a lid, and a bellows-like cover 12 that surrounds the outside of the frame 11, forming an enclosed space inside.

[0047] The laser irradiation mechanism 20 has a laser gun 21 that irradiates a laser beam LB downward toward the surface S of the concrete structure CS. The laser gun 21 has a built-in combination lens 22 for irradiating the laser beam LB. The laser gun 21 is connected to a laser oscillator 21L via an optical fiber 21F.

[0048] An air injection nozzle 23 (gas injection mechanism) is also attached to the laser irradiation mechanism 20. The air injection nozzle 23 constantly blows injected air JA sideways along an objective lens surface 22S, which is the lens surface facing the surface S of the concrete structure CS of the lens (objective lens) closest to the surface S of the compound lens 22, while the laser irradiation mechanism 20 is in operation. The air injection nozzle 23 is connected to an air compressor 23C via an air hose 23H.

[0049] The laser beam LB is generated by a laser oscillator 21L and is emitted downward from the laser gun 21 via an optical fiber 21F. On the other hand, the jet air JA is generated by an air compressor 23C and is blown sideways from the air jet nozzle 23 via an air hose 23H.

[0050] The water injection mechanism 30 sprays water (mist) ultrasonically atomized by the ultrasonic atomizer 32 (atomization mechanism) obliquely downward from the spray nozzle 31 as ultrasonic mist UM. The ultrasonic atomizer 32 is connected to the pump 32P via the hose 23H. Water in the tank 32T is pumped up by the pump 32P and reaches the ultrasonic atomizer 32 via the hose 23H, where it becomes ultrasonic mist UM and is sprayed obliquely downward from the spray nozzle 31. In addition, a portion of the spray air JA blown from the air injection nozzle 23 is introduced into the spray nozzle 31, and the ultrasonic mist UM sprayed from the spray nozzle 31 is accelerated by the spray air JA.

[0051] The particle size of ultrasonic mist UM is generally about 0.001 to 0.01 mm (average 0.005 mm). Therefore, the particle size of ultrasonic mist UM can be made smaller than both the closed air bubbles CC and the entrained air bubbles MC present in the concrete structure CS.

[0052] The suction mechanism 40 has a negative pressure pump 41 (suction fan) for negatively sucking the contaminated air DA generated in the decontamination booth 10, and a dust collector 42 with a built-in air filter 42F that is connected to the outlet side of a flexible hose 42H arranged in the suction flow path of the negative pressure pump 41. The inlet side (suction side) of the flexible hose 42H opens into the decontamination booth 10.

[0053] The power supply equipment 90 supplies driving power to the laser oscillator 21L, the air compressor 23C, the pump 32P, the ultrasonic atomizer 32, and the negative pressure pump 41. In Fig. 1, the dashed dotted lines indicate power supply lines.

[0054] Next, decontamination of a concrete structure CS using the decontamination equipment 100 will be described, primarily with reference to Figure 2. Simultaneously with the downward irradiation of a laser beam LB by the laser gun 21 of the laser irradiation mechanism 20, ultrasonic mist UM is sprayed obliquely downward from the spray nozzle 31 of the water injection mechanism 30 at the same location as the laser beam LB. When the ultrasonic mist UM reaches the surface S, it cools the surface S due to the heat of vaporization generated during evaporation. It also penetrates the closed bubbles CC and entrained bubbles MC of the contaminated layer without melting the surface S, or even if it does melt partially, before vitrification occurs. The mist rapidly expands within these bubbles CC and MC, causing a steam explosion-like phenomenon that peels off and destroys the contaminated layer, releasing them as contaminated fragments PP. The contaminated fragments PP, together with the sprayed air JA from the air injection nozzle 23, become contaminated air DA, which is vacuum-suctioned by the vacuum pump 41, passes through a flexible hose 42H, and is captured by the air filter 42F of the dust collector 42 (see Figure 1).

[0055] In this way, the occurrence of vitrification can be easily avoided without constantly monitoring the temperature of the surface S during decontamination work and controlling the output of the laser beam LB. In addition, the ultrasonic mist UM is vaporized and collected together with the peeled and destroyed contaminated pieces PP, so the occurrence of secondary contamination can also be easily avoided.

[0056] In this embodiment, the laser gun 21 irradiates the laser beam LB downward, and the spray nozzle 31 sprays the ultrasonic mist UM diagonally downward, but the directions may be interchanged. That is, the spray nozzle 31 can be changed to spray downward, and the laser gun 21 can be changed to irradiate diagonally downward. Alternatively, both may be changed to irradiate diagonally downward, and further, the inclination angles of the two may be different.

[0057] Figure 3 is an explanatory diagram showing a schematic diagram of a decontamination system for an open road surface work area as a first example of a decontamination system according to the present invention. The decontamination system for an open road surface work area (hereinafter simply referred to as the decontamination system) 1000 shown in Figure 3 decontaminates the ground surface (surface portion) of a concrete pavement CP (e.g., a paved road in a nuclear power plant) as a concrete structure. The decontamination system 1000 includes a decontamination booth 10 (decontamination room) connected to a suction mechanism 40 and forming a closed negative-pressure space surrounding the surface portion S of the concrete pavement CP (see Figure 2), a laser irradiation mechanism 20 that irradiates the surface portion S of the concrete pavement CP with a laser beam LB, a water injection mechanism 30 (liquid injection mechanism) that sprays ultrasonically atomized ultrasonic mist UM onto the surface portion S, and a controller 200 (controller) that issues control signals to the laser irradiation mechanism 20 and the water injection mechanism 30.

[0058] Furthermore, the decontamination system 1000 further includes a mobile work vehicle 300 (moving device) that tows the decontamination booth 10, laser irradiation mechanism 20, and water injection mechanism 30, is equipped with a controller 200, and is capable of collectively changing its position relative to a surface portion S in the work area (road surface) to be decontaminated in response to a control signal issued from the controller 200. The frame 11 of the decontamination booth 10 is connected (towed) to the mobile work vehicle 300 by a connecting bar 310 (connecting mechanism), and casters 13 are attached to the lower end of the frame 11 for moving on the road surface.

[0059] The power supply equipment 90 supplies driving power to the laser oscillator 21L, air compressor 23C, pump 32P, ultrasonic atomizer 32, negative pressure pump 41, and controller 200. Meanwhile, the controller 200 issues control signals to the laser gun 21, air injection nozzle 23, spray nozzle 31, power supply equipment 90, and mobile work vehicle 300. In Fig. 3, the dot-dash lines represent power supply lines, and the dashed lines represent control signal lines. This also applies to the following figures.

[0060] Next, Figure 4 shows a process diagram based on the decontamination system of Figure 3. First, in S1, an ON command is issued to the power supply equipment 90, starting the laser oscillator 21L, air compressor 23C, pump 32P, ultrasonic atomizer 32, and negative pressure pump 41 to prepare for decontamination. In S2, the laser gun 21, air injection nozzle 23, and spray nozzle 31 are operated synchronously to carry out the decontamination work. In S3, an automatic operation command is issued to the mobile work vehicle 300, and it moves within the road surface opening work area. In S4, it is confirmed whether the end of the road surface opening work area has been reached and the decontamination work has been completed, and if the end has not been reached (NO in S4), the process returns to S2, and if the end has been reached (YES in S4), the process ends.

[0061] Figure 5 is an explanatory diagram showing a decontamination system for an open-wall work area as a second example of a decontamination system according to the present invention. The decontamination system for an open-wall work area (hereinafter simply referred to as the decontamination system) 2000 shown in Figure 5 decontaminates the outer wall surface (surface portion) of a concrete structure, such as a concrete retaining wall CW (e.g., a protective wall in a nuclear power plant). The decontamination system 2000 includes a decontamination booth 10 (decontamination room) connected to a suction mechanism 40 and forming a closed negative-pressure space surrounding the surface portion S (see Figure 2) of the concrete retaining wall CW; a laser irradiation mechanism 20 that irradiates the surface portion S of the concrete retaining wall CW with a laser beam LB; a water injection mechanism 30 (liquid injection mechanism) that sprays ultrasonically atomized ultrasonic mist UM onto the surface portion S; and a controller 200 (controller) that issues control signals to the laser irradiation mechanism 20 and the water injection mechanism 30.

[0062] Furthermore, the decontamination system 2000 holds the decontamination booth 10, the laser irradiation mechanism 20, and the water injection mechanism 30, and is equipped with a controller 200, and further includes an aerial work vehicle 400 (moving device) and a lifting device 500 (moving device) that can collectively change their positions relative to a surface portion S in the work area (exterior wall surface) to be decontaminated by a control signal issued from the controller 200. The frame 11 of the decontamination booth 10 is connected to a winding transmission mechanism 520 (for example, a roller chain driven by a motor 510) of the lifting device 500 by a connecting link 530 (connecting mechanism), and casters 13 are attached to the tip of the frame 11 for moving along the exterior wall surface.

[0063] The power supply equipment 90 supplies driving power to the laser oscillator 21L, the air compressor 23C, the pump 32P, the ultrasonic atomizer 32, the negative pressure pump 41, the motor 510, and the controller 200. Meanwhile, the controller 200 issues control signals to the laser gun 21, the air injection nozzle 23, the spray nozzle 31, the power supply equipment 90, the motor 510, and the aerial work vehicle 400.

[0064] Next, Figure 6 shows a process diagram based on the decontamination system of Figure 5. First, in S1, an ON command is issued to the power supply equipment 90, starting the laser oscillator 21L, air compressor 23C, pump 32P, ultrasonic atomizer 32, and negative pressure pump 41 to prepare for decontamination. In S2, the laser gun 21, air injection nozzle 23, and spray nozzle 31 are synchronously operated to perform decontamination work. In S3', an automatic operation command is issued to the aerial work vehicle 400, and an elevation drive command is issued to the lifting device 500, causing it to move within the wall-opening work area. In S4, it is confirmed whether the end of the wall-opening work area has been reached and the decontamination work has been completed. If the end has not been reached (NO in S4), the process returns to S2; if the end has been reached (YES in S4), the process ends. Note that in S3', the aerial work vehicle 400 can also move in a direction perpendicular to the plane of the paper in Figure 5 (i.e., along the outer wall surface of the concrete retaining wall CW), etc.

[0065] Figure 7 is an explanatory diagram showing a decontamination system for a closed work area inside a building as a third example of a decontamination system according to the present invention. The decontamination system for a closed work area inside a building (hereinafter simply referred to as the decontamination system) 3000 shown in Figure 7 decontaminates the inner wall and ceiling surfaces (surfaces) of a concrete building CH (e.g., a spent nuclear fuel storage facility in a nuclear power plant), which is a concrete structure. The decontamination system 3000 includes a decontamination booth 10 (decontamination room) connected to a suction mechanism 40 and forming a closed negative-pressure space surrounding the surface S (see Figure 2) of the concrete building CH, a laser irradiation mechanism 20 that irradiates the surface S of the concrete building CH with a laser beam LB, a water injection mechanism 30 (liquid injection mechanism) that sprays ultrasonically atomized ultrasonic mist UM onto the surface S, and a controller 200 (controller) that issues control signals to the laser irradiation mechanism 20 and the water injection mechanism 30.

[0066] Furthermore, the decontamination system 3000 is equipped with a decontamination booth 10, a laser irradiation mechanism 20, and a water spraying mechanism 30, and further includes a mobile work platform 600 (moving device) and a robot arm 700 (moving device) that can simultaneously change their positions relative to a surface S in the work area (inner wall and ceiling surfaces) to be decontaminated, and a controller 200 is disposed in a remote location outside the work area (inner wall and ceiling surfaces). The mobile work platform 600 and the robot arm 700 change the positions of the decontamination booth 10, the laser irradiation mechanism 20, and the water spraying mechanism 30 within the work area (inner wall and ceiling surfaces) in response to control signals issued based on remote operation by the controller 200. The frame 11 of the decontamination booth 10 is connected to the mobile work platform 600 by the robot arm 700, and casters 13 are attached to the tip of the frame 11 for moving along the inner wall and ceiling surfaces.

[0067] Power supply equipment 90 supplies driving power to laser oscillator 21L, air compressor 23C, pump 32P, ultrasonic atomizer 32, negative pressure pump 41, mobile work platform 600, robot arm 700, and controller 200. Meanwhile, controller 200 issues control signals to laser gun 21, air injection nozzle 23, spray nozzle 31, power supply equipment 90, mobile work platform 600, and robot arm 700.

[0068] Next, Figure 8 shows a process diagram based on the decontamination system of Figure 7. First, in S1, an ON command is issued to the power supply equipment 90, starting the laser oscillator 21L, air compressor 23C, pump 32P, ultrasonic atomizer 32, and negative pressure pump 41 to prepare for decontamination. In S2, the laser gun 21, air injection nozzle 23, and spray nozzle 31 are operated synchronously to carry out the decontamination work. In S3", an automatic travel command is issued to the mobile work platform 600, and drive commands to rotate and extend are issued to the robot arm 700, causing it to move within the enclosed work area within the building. In S4, it is confirmed whether the end of the enclosed work area within the building has been reached as a result of the movement and the decontamination work has been completed; if the end has not been reached (NO in S4), the process returns to S2; if the end has been reached (YES in S4), the process ends.

[0069] Figure 9 is an explanatory diagram showing a schematic diagram of a decontamination system for a closed work area inside a tunnel as a fourth example of a decontamination system according to the present invention. The decontamination system for a closed work area inside a tunnel (hereinafter simply referred to as the decontamination system) 4000 shown in Figure 9 decontaminates the inclined inner surface (surface) of a concrete tunnel CT (e.g., a highway or subway tunnel) as a concrete structure. The decontamination system 4000 includes a decontamination booth 10 (decontamination room) connected to a suction mechanism 40 and forming a closed negative-pressure space surrounding the surface S (see Figure 2) of the concrete tunnel CT, a laser irradiation mechanism 20 that irradiates the surface S of the concrete tunnel CT with a laser beam LB, a water injection mechanism 30 (liquid injection mechanism) that sprays ultrasonically atomized ultrasonic mist UM onto the surface S, and a controller 200 (controller) that issues control signals to the laser irradiation mechanism 20 and the water injection mechanism 30.

[0070] Furthermore, the decontamination system 4000 is equipped with a decontamination booth 10, a laser irradiation mechanism 20, and a water spraying mechanism 30, and further includes a mobile work platform 600 (moving device) and a robot arm 700 (moving device) that can change their positions collectively relative to the surface portion S in the work area (inclined inner surface) that is the target of decontamination, and a controller 200 is disposed in a remote location outside the work area (inclined inner surface). The mobile work platform 600 and the robot arm 700 change the positions of the decontamination booth 10, the laser irradiation mechanism 20, and the water spraying mechanism 30 within the work area (inclined inner surface) in response to control signals issued based on remote operation by the controller 200. The frame 11 of the decontamination booth 10 is connected to the mobile work platform 600 by the robot arm 700, and casters 13 are attached to the tip of the frame 11 for moving along the inclined inner surface.

[0071] Power supply equipment 90 supplies driving power to laser oscillator 21L, air compressor 23C, pump 32P, ultrasonic atomizer 32, negative pressure pump 41, mobile work platform 600, robot arm 700, and controller 200. Meanwhile, controller 200 issues control signals to laser gun 21, air injection nozzle 23, spray nozzle 31, power supply equipment 90, mobile work platform 600, and robot arm 700.

[0072] The process diagram based on the decontamination system in Figure 9 is the same as that in Figure 8, so it is omitted here.

[0073] In each embodiment of the decontamination systems 1000, 2000, 3000, and 4000 (Figures 3, 5, 7, and 9), parts having functions common to those of the decontamination apparatus 100 (Figure 1) are given the same reference numerals and detailed explanations are omitted.

[0074] These embodiments can be combined as appropriate within the scope of not causing technical contradictions.Furthermore, the present invention is not limited to the radioactive materials described in the concrete structure CS (Fig. 2), but can be applied to general methods, devices and systems for removing pollutants that contaminate the environment, such as toxic substances and bacteria, that contaminate the air, water, soil, etc. [Explanation of symbols]

[0075] 10 Decontamination booth (decontamination room) 11 frames 12 Accordion cover 13 Caster 20 Laser irradiation mechanism 21 Laser Gun 21F Optical Fiber 21L Laser Oscillator 22 Combination Lenses 22S objective lens surface 23 Air injection nozzle (gas injection mechanism) 23C Air Compressor 23H Air Hose 30 Water injection mechanism (liquid injection mechanism) 31 Spray nozzle 32 Ultrasonic atomizer (atomization mechanism) 32H hose 32P Pump 32T tank 40 Suction mechanism 41 Negative pressure pump (suction fan) 42 Dust collector 42F Air Filter 42H flexible hose 90 Power equipment 100 Decontamination Equipment 200 Controller (control unit) 300 Mobile work vehicle (mobile device) 310 Connecting bar (connecting mechanism) 1000 Decontamination system for open road work areas (decontamination system) 400 High-altitude work vehicle (mobile device) 500 Elevating device (moving device) 510 Motor 520 Winding transmission mechanism 530 Connecting link (connecting mechanism) 2000 Decontamination system for open-wall work areas (decontamination system) 600 Mobile work cart (mobile device) 700 Robot Arm (Moving Device) 3000 Decontamination system for closed work areas inside buildings (decontamination system) 4000 Decontamination system for closed work areas in tunnels (decontamination system) B Mounting table CS Concrete Structure CA coarse aggregate FA fine aggregate CC Closed Cell MC Entrapped air bubbles PP Contaminated Pieces S Surface (contaminated layer) CP Concrete Pavement (Concrete Structure) CW Concrete retaining wall (concrete structure) CH Concrete building (concrete structure) CT Concrete Tunnel (Concrete Structure) LB laser beam UM Ultrasonic Mist JA Injected Air DA Contaminated Air

Claims

1. A method for decontaminating an inorganic structure that contains inorganic solid particles, has a large number of bubbles present therein, and has a contaminated layer at least on its surface that is contaminated with a contaminant, comprising: A decontamination method characterized by irradiating a laser beam onto the surface in a closed negative pressure space surrounding the surface, and simultaneously spraying atomized or atomized liquid at the same location as the laser beam irradiation position so that the liquid is rapidly heated by the laser beam at least inside bubbles located on the surface and rapidly expands, thereby peeling off, destroying, and removing the contaminated layer.

2. A method for decontaminating a concrete structure that contains inorganic solid particles as aggregate, has air bubbles present in the form of numerous fine closed bubbles and larger entrained bubbles, and has a contaminated layer at least on the surface that is contaminated with a contaminant, comprising: A decontamination method characterized by irradiating a laser beam onto the surface in a closed negative pressure space surrounding the surface, and simultaneously spraying atomized or atomized liquid at the same location as the laser beam irradiation position so that the liquid is rapidly heated by the laser beam at least inside bubbles located on the surface and rapidly expands, thereby peeling off, destroying, and removing the contaminated layer.

3. The liquid sprayed toward the surface portion cools the surface portion heated by the laser beam to prevent melting, and 3. A decontamination method according to claim 1 or claim 2, wherein liquid having a particle size smaller than that of the bubbles in the contaminated layer and entering the bubbles in the contaminated layer is rapidly heated by the laser beam, and expands rapidly within the bubbles, peeling off and destroying the contaminated layer.

4. 4. The decontamination method according to claim 1, wherein the irradiation of the laser beam and the injection of the liquid are carried out continuously or intermittently in synchronization with each other at the same location on the contaminated layer.

5. A decontamination device for an inorganic structure that contains inorganic solid particles, has a large number of bubbles present therein, and has a contaminated layer at least on its surface that is contaminated by a contaminant, a decontamination chamber to which a suction mechanism is connected and which forms a closed negative pressure space surrounding the surface portion; a laser irradiation mechanism that irradiates the surface portion with a laser beam; a liquid injection mechanism that injects atomized or atomized liquid onto the surface, A decontamination device characterized in that, within the decontamination chamber, the laser irradiation mechanism irradiates the surface portion with a laser beam, and at the same time, the liquid injection mechanism injects atomized or misted liquid at the same location as the laser beam irradiation position so that the liquid is rapidly heated by the laser beam at least inside bubbles located on the surface portion and rapidly expands, and the suction mechanism sucks up and removes the peeled or destroyed contaminated layer.

6. A decontamination device for a concrete structure that contains inorganic solid particles as aggregate, has air bubbles in the form of a large number of fine closed bubbles and larger entrained bubbles, and has a contaminated layer at least on the surface that is contaminated with a contaminant, a decontamination chamber to which a suction mechanism is connected and which forms a closed negative pressure space surrounding the surface portion; a laser irradiation mechanism that irradiates the surface portion with a laser beam; a liquid injection mechanism that injects atomized or atomized liquid onto the surface, A decontamination device characterized in that, within the decontamination chamber, the laser irradiation mechanism irradiates the surface portion with a laser beam, and at the same time, the liquid injection mechanism injects atomized or misted liquid at the same location as the laser beam irradiation position so that the liquid is rapidly heated by the laser beam at least inside bubbles located on the surface portion and rapidly expands, and the suction mechanism sucks up and removes the peeled or destroyed contaminated layer.

7. 7. The decontamination apparatus according to claim 5, wherein the liquid spraying mechanism sprays mist having a particle size smaller than that of bubbles in the contaminated layer by ultrasonic atomization.

8. the laser irradiation mechanism is provided with a single lens or a combination of lenses for irradiating a laser beam, and a gas injection mechanism for blowing air onto an objective lens surface, which is a lens surface facing the surface of the lens closest to the surface among these lenses; 8. The decontamination apparatus according to claim 5, wherein the gas injection mechanism constantly blows air toward the objective lens surface while the laser irradiation mechanism is in operation.

9. A decontamination system for an inorganic structure that contains inorganic solid particles, has a large number of bubbles present therein, and has a contaminated layer at least on its surface that is contaminated by a contaminant, a decontamination chamber to which a suction mechanism is connected and which forms a closed negative pressure space surrounding the surface portion; a laser irradiation mechanism that irradiates the surface portion with a laser beam; a liquid injection mechanism that injects atomized or atomized liquid onto the surface; a control unit that issues control signals to the laser irradiation mechanism and the liquid ejection mechanism, The control unit is configured to, within the decontamination chamber, cause the laser irradiation mechanism to irradiate the surface portion with a laser beam, and at the same time, cause the liquid injection mechanism to inject the atomized or misted liquid at the same location as the laser beam irradiation position so that the liquid is rapidly heated by the laser beam at least inside bubbles located on the surface portion and rapidly expands, and to issue a control signal so that the suction mechanism sucks up and removes the peeled or destroyed contaminated layer.

10. A decontamination system for a concrete structure that contains inorganic solid particles as aggregate, has air bubbles in the form of a large number of fine closed bubbles and larger entrained bubbles, and has a contaminated layer at least on the surface that is contaminated with a contaminant, a decontamination chamber to which a suction mechanism is connected and which forms a closed negative pressure space surrounding the surface portion; a laser irradiation mechanism that irradiates the surface portion with a laser beam; a liquid injection mechanism that injects atomized or atomized liquid onto the surface; a control unit that issues control signals to the laser irradiation mechanism and the liquid ejection mechanism, The control unit is configured to, within the decontamination chamber, cause the laser irradiation mechanism to irradiate the surface portion with a laser beam, and at the same time, cause the liquid injection mechanism to inject the atomized or misted liquid at the same location as the laser beam irradiation position so that the liquid is rapidly heated by the laser beam at least inside bubbles located on the surface portion and rapidly expands, and to issue a control signal so that the suction mechanism sucks up and removes the peeled or destroyed contaminated layer.

11. 11. The decontamination system according to claim 9 or claim 10, further comprising a moving device that carries or pulls the decontamination chamber, the laser irradiation mechanism, the liquid injection mechanism, and the control unit, and that can collectively change the position of the decontamination chamber, the laser irradiation mechanism, the liquid injection mechanism, and the control unit relative to the surface portion in a work area to be decontaminated in response to a control signal issued from the control unit.

12. a moving device that is equipped with the decontamination chamber, the laser irradiation mechanism, and the liquid injection mechanism and that can collectively change the position of the decontamination chamber, the laser irradiation mechanism, and the liquid injection mechanism relative to the surface portion in the work area to be decontaminated; The control unit is disposed at a predetermined position outside the working area, 11. The decontamination system according to claim 9 or 10, wherein the moving device changes the positions of the decontamination chamber, the laser irradiation mechanism, and the liquid ejection mechanism within a working area in response to a control signal issued based on remote operation by the control unit.

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