JP7630766B2 - Laser Decontamination System - Google Patents

Description

The present invention relates to a laser decontamination system, and in particular to a laser decontamination system that decontaminates the surfaces of metal-contaminated waste such as pipes.

During decommissioning and maintenance of a nuclear reactor, radioactive metal waste (hereafter referred to as "metallic contaminated waste") is generated, including pipes, tanks, steel beams, and various equipment. This metallic contaminated waste is broadly divided into high-level radioactive waste and low-level radioactive waste, depending on the level of contamination.

High-level radioactive waste is disposed of in the ground (buried 300m or more underground) because it contains radioactive materials with high concentrations and long half-lives. Low-level radioactive waste is classified according to the level of contamination into three types: clearance level L1, which has a relatively high level of radioactivity and is disposed of at a marginal depth (buried 50m or more underground), clearance level L2, which has a relatively low level of radioactivity and is disposed of in shallow pits, and clearance level L3, which has an extremely low level of radioactivity and is disposed of in shallow trenches.

As the level of contamination of metal-contaminated waste increases, disposal costs increase, and there is a demand to decontaminate the waste to reduce the level of contamination as much as possible. Methods for decontaminating metal-contaminated waste include chemical decontamination, mechanical decontamination such as blasting, laser decontamination, and electrolytic polishing decontamination, as described in, for example, Patent Documents 1 and 2.

Japanese Patent Application Publication No. 8-94796 JP 2004-77162 A

However, decontamination methods such as chemical decontamination, mechanical decontamination, and electrolytic polishing decontamination have the problem of generating large amounts of secondary waste, such as chemical liquids, abrasives, and electrolytes, after decontamination processing. Processing equipment, including measures to prevent the diffusion of secondary waste, tends to be large-scale, which can easily increase decontamination costs. In addition, laser decontamination has the problem of low work efficiency, as decontamination is performed manually by workers. Since large amounts of low-level radioactive waste are generated during decommissioning, work efficiency has a large impact on decontamination costs.

The present invention was devised in consideration of these problems, and aims to provide a laser decontamination system that can reduce the amount of secondary waste generated and improve work efficiency.

According to the present invention, a decontamination unit is provided with a container housing a laser decontamination device capable of decontaminating metal-contaminated waste, a ventilation unit is provided with a container housing a filter device capable of recovering contaminants generated by use of the laser decontamination device, a plurality of ducts configured to be detachable and capable of circulating air between a decontamination area of the decontamination unit and the ventilation unit, a tray configured in a lattice shape having a plurality of openings on which the metal-contaminated waste is placed, and a transport cart for moving the tray within the decontamination unit, and the laser decontamination device is a first laser decontamination device capable of decontaminating an upper surface of the metal-contaminated waste placed on the tray in the decontamination area. and a second laser decontamination device capable of decontaminating the underside of the metal-contaminated waste placed on a tray in the decontamination area by irradiating a laser beam from an opening of the tray, wherein the first laser decontamination device is configured to be movable along the longitudinal direction of the decontamination area and includes a laser irradiation unit configured to be movable up and down depending on the height of the metal-contaminated waste placed on the tray, and the second laser decontamination device is configured to be movable along the longitudinal direction of the decontamination area and includes a laser irradiation unit configured to be movable in a direction parallel to the bottom surface of the tray and perpendicular to the longitudinal direction .

The groove of the tray is a complex structure formed along the longitudinal direction by a frame formed in a mountain shape. The second laser decontamination device is provided with a plurality of grooves, and the second laser decontamination device is provided with a plurality of grooves on the bottom surface of the tray. A laser irradiation unit in the front row is configured to be movable diagonally in the direction of the tray. A rear row of laser irradiation units configured to be movable diagonally with respect to the other surface of the bottom surface. It's okay to do that.

According to the laser decontamination system of the present invention described above, by dividing the decontamination unit and ventilation unit into separate containers, the decontamination equipment can be easily transported and decontamination treatment can be performed at the desired location, improving work efficiency. In addition, by adopting a laser decontamination method for the decontamination equipment and performing decontamination treatment in a closed space in the decontamination area, the amount of secondary waste generated can be reduced and the spread of contaminants can be suppressed.

1 is an overall configuration diagram showing a laser decontamination system according to an embodiment of the present invention. FIG. 2 is an enlarged view of the decontamination unit shown in FIG. 1 . FIG. 2 is an enlarged view of the ventilation unit shown in FIG. 1 . 2A to 2D are explanatory views of the tray shown in FIG. 1, in which (a) is a plan view, (b) is a side view, (c) is a front view, and (d) is a perspective view of the tray placed on a transport cart. FIG. 2 is an enlarged view of the laser decontamination apparatus shown in FIG. 1 . 5A and 5B are explanatory views of a decontamination process by the first laser decontamination apparatus, in which FIG. 5A is a plan view and FIG. 5B is a front view. 5A to 5C are explanatory views of the decontamination process by the second laser decontamination apparatus, in which (a) is a plan view, (b) is a front view of the front row, and (c) is a front view of the rear row.

Embodiments of the present invention will be described below with reference to Figs. 1 to 7(c). Fig. 1 is an overall configuration diagram showing a laser decontamination system according to one embodiment of the present invention. Fig. 2 is an enlarged view of the decontamination unit shown in Fig. 1. Fig. 3 is an enlarged view of the ventilation unit shown in Fig. 1. Note that Figs. 2 and 3 show a see-through view of the side of the container.

The laser decontamination system 1 according to one embodiment of the present invention comprises a decontamination unit 2 having a container housing a laser decontamination device 21 capable of decontaminating metal contaminated waste, a ventilation unit 3 having a container housing a filter device 31 capable of collecting contaminants generated by the use of the laser decontamination device 21, and a number of ducts 4 configured to be removable and capable of circulating air between the decontamination area 2a of the decontamination unit 2 and the ventilation unit 3.

The decontamination unit 2 is composed of, for example, a 40-foot container standardized by the International Organization for Standardization (ISO). The inside of the container of the decontamination unit 2 is divided into a decontamination area 2a where decontamination work is carried out, and a work area 2b where metal contaminated waste is transported in and out and the laser decontamination system 1 is operated.

An airtight door 2c is placed between the decontamination area 2a and the work area 2b, and is configured to hermetically seal the decontamination area 2a. Metallic waste contaminated waste is transported into and out of the decontamination area 2a on trays 2d. The metal waste contaminated waste is radioactive metal waste such as pipes, tanks, steel beams, and various equipment used in the nuclear reactor facility, and is cut on-site to a size that can be placed on the trays 2d.

In the decontamination area 2a, guide rails 2e that guide the trays 2d are arranged along the longitudinal direction of the container. The trays 2d are carried into the work area 2b while being placed on a transport cart 2f, and are handed over to the guide rails 2e at the entrance of the decontamination area 2a. The guide rails 2e are configured to be able to support multiple trays 2d.

In the decontamination area 2a, a relay terminal box 2g that supplies power and performs communication for various internal devices, a laser oscillator storage box 2h that stores a laser oscillator that supplies laser light to the laser decontamination device 21, a surveillance camera 2i, lighting 2j, etc. are installed. For example, the laser oscillator can be air-cooled to eliminate the need for cooling water, improving mobility.

The work area 2b is composed of the area between the container's opening and closing door 2k and the airtight door 2c. A control and operation panel 2m is placed in the work area 2b to control the operation of the laser decontamination device 21 and monitor the decontamination process. Images from a surveillance camera 2i placed in the decontamination area 2a are displayed, for example, on a monitor placed on the control and operation panel 2m.

The ventilation unit 3 is, for example, a 20-foot container standardized by the International Organization for Standardization (ISO). The duct 4 is composed of an exhaust duct 41 that draws air from the decontamination area 2a into the filter device 31, and an air supply duct 42 that supplies air from within the ventilation unit 3 to the decontamination area 2a.

A filter device 31 that adsorbs contaminants generated during decontamination processing is placed inside the container. The filter device 31 stores multiple adsorption filters. The multiple adsorption filters may be of the same type or different types.

An exhaust duct 41 is connected to the upstream side of the filter device 31, and a suction blower 32 is connected to the downstream side of the filter device 31. An exhaust nozzle 33 that exhausts the treated air into the container is connected to the downstream side of the suction blower 32. A cooler for lowering the exhaust temperature may be placed between the filter device 31 and the exhaust nozzle 33.

The air supply duct 42 is connected to an air supply filter 34 that removes dust particles from the air. The air supply filter 34 is placed inside the container of the ventilation unit 3, and the upstream side of the air supply filter 34 is open inside the container. The air inside the container is sent into the decontamination area 2a due to the pressure difference.

In addition, since contaminants have been removed from the air that has passed through the filter device 31, it is not necessary to seal the container passages of the exhaust duct 41 and the supply duct 42. In addition, lighting and surveillance cameras may be installed inside the container of the ventilation unit 3, if necessary.

Here, FIG. 4 is an explanatory diagram of the tray shown in FIG. 1, where (a) is a plan view, (b) is a side view, (c) is a front view, and (d) is a perspective view of the tray placed on the transport cart.

As shown in FIG. 4(a), the tray 2d is configured in a lattice shape in a plan view and has multiple openings 2n in the longitudinal and lateral directions. By forming the openings 2n in the tray 2d, decontamination processing can be performed from both the upper and lower surfaces of the tray 2d.

The tray 2d may also have multiple grooves 2p formed along the longitudinal direction, as shown in Figures 4(b) and 4(c). With this configuration, the metal-contaminated waste can be stably placed along the grooves 2p. The grooves 2p are formed, for example, by forming the short-side frame that forms the openings 2n into a mountain shape.

The transport cart 2f includes, for example, a support member 2q that supports the tray 2d, a plurality of rollers 2r arranged at the lower end of the support member 2q, a receiving tray 2s that collects objects that fall from the tray 2d, and a sending device 2t for the tray 2d. Note that the transport cart 2f is not limited to the configuration shown in the figure.

The support members 2q are configured to support both ends of the tray 2d in the short direction so that they can be guided. The rollers 2r are, for example, motorized rollers for moving heavy objects. The transport cart 2f is configured to be self-propelled by cooperative control of the four rollers 2r. The receiving tray 2s is formed to be large enough to cover at least the opening 2n of the tray 2d. The sending device 2t is configured to smoothly move the tray 2d from the transport cart 2f to the guide rails 2e in the decontamination area 2a.

Here, Fig. 5 is an enlarged view of the laser decontamination device shown in Fig. 1. Fig. 6 is an explanatory diagram of the decontamination process by the first laser decontamination device, where (a) is a plan view and (b) is a front view. Fig. 7 is an explanatory diagram of the decontamination process by the second laser decontamination device, where (a) is a plan view, (b) is a front view of the front row, and (c) is a front view of the back row.

As shown in FIG. 5, the laser decontamination device 21 includes a first laser decontamination device 211 capable of decontaminating the upper surface of the metal-contaminated waste placed in the decontamination area 2a, and a second laser decontamination device 212 capable of decontaminating the lower surface of the metal-contaminated waste placed in the decontamination area 2a. Note that the first laser decontamination device 211 and the second laser decontamination device 212 are not limited to the configuration shown in the figure.

The first laser decontamination device 211 includes, for example, a traveling carriage 211a that can move along a first guide rail 21a (see FIG. 2) laid in the longitudinal direction of the decontamination area 2a, a laser irradiation unit 211b that is arranged on the traveling carriage 211a so as to be movable in the vertical direction, and a surveillance camera 211c that is arranged on the traveling carriage 211a.

The traveling cart 211a has, for example, a gate-shaped structure equipped with traveling wheels. The laser irradiation unit 211b has, for example, a laser head 211d that irradiates laser light toward the upper surface of the metal-contaminated waste W, and a distance sensor 211e that is disposed at the tip of the laser head 211d and measures the distance to the metal-contaminated waste W, as shown in FIG. 6(b). Laser light is supplied to the laser head 211d via an optical fiber from a laser oscillator stored in a laser oscillator storage box 2h in the decontamination area 2a.

The traveling cart 211a is controlled to move along the longitudinal direction of the decontamination area 2a. Therefore, the laser light emitted from the laser head 211d moves along the longitudinal direction of the tray 2d as shown in FIG. 6(a), and decontaminates the top surface of the metal-contaminated waste placed on the tray 2d. Note that for ease of explanation, the illustration of the metal-contaminated waste is omitted in FIG. 6(a).

The laser heads 211d are unitized into a set of two, and are configured to be movable along guide rails 211f fixed to the traveling cart 211a. If the direction from the back of the decontamination area 2a toward the airtight door 2c is defined as the forward direction of movement, as shown in FIG. 5, three laser irradiation units 211b are arranged in the front row and two in the back row. At this time, the laser irradiation units 211b are arranged so that the laser light irradiated from the laser heads 211d is aligned at equal intervals in a direction perpendicular to the direction of movement.

As shown in FIG. 6(b), the distance sensor 211e measures the distance to the metal-contaminated waste W, and the height (vertical position) of the laser head 211d is controlled so as to fall within the range in which decontamination is possible. In other words, the laser irradiation unit 211b is configured to be movable in the vertical direction so as to maintain the distance z between the metal-contaminated waste W and the laser head 211d approximately constant according to the height of the metal-contaminated waste W placed on the tray 2d.

In FIG. 6(b), for ease of explanation, the traveling carriage 211a and the guide rail 2e are omitted. Also, in FIG. 6(b), for ease of explanation, the front row of laser irradiation units 211b are shown in solid lines, and the rear row of laser irradiation units 211b are shown in dashed lines.

For example, as shown in FIG. 2, when three trays 2d are placed in the decontamination area 2a, the height of the metal contaminated waste W differs for each tray 2d, so the height (vertical position) of the laser head 211d is automatically controlled in accordance with the movement of the first laser decontamination device 211.

The second laser decontamination device 212 includes, for example, a traveling carriage 212a that can move along a second guide rail 21b (see FIG. 2) laid in the longitudinal direction of the decontamination area 2a, a laser irradiation unit 212b that is arranged on the traveling carriage 212a so as to be movable in an oblique direction, and a surveillance camera 212c that is arranged on the traveling carriage 212a.

The traveling cart 212a has, for example, a table-type structure equipped with traveling wheels. The laser irradiation unit 212b has, for example, as shown in Figures 6(b) and 6(c), a laser head 212d that irradiates laser light toward the underside of the metal contaminated waste W, and a slide mechanism configured to be able to move the laser head 212d in a direction parallel to the bottom surface of the tray 2d and perpendicular to the moving direction. Laser light is supplied to the laser head 212d via an optical fiber from a laser oscillator stored in a laser oscillator storage box 2h in the decontamination area 2a.

The laser head 212d is configured to be movable along a slope formed on a base 212e fixed to the traveling cart 212a. If the direction from the back of the decontamination area 2a toward the airtight door 2c is defined as the forward direction of movement, as shown in FIG. 5, four laser irradiation units 212b are arranged in a front row and four in a rear row. At this time, the laser irradiation units 211b are arranged so that the laser light irradiated from the laser head 211d is aligned at equal intervals in a direction perpendicular to the direction of movement.

The base 212e of the laser irradiation unit 212b arranged in the front row has a slope 212f that is approximately parallel to the bottom surface 2u that forms the groove 2p of the tray 2d, as shown in FIG. 7(b), for example. The base 212e of the laser irradiation unit 212b arranged in the rear row has a slope 212g that is approximately parallel to the bottom surface 2v that forms the groove 2p of the tray 2d, as shown in FIG. 7(c), for example.

The traveling cart 212a is controlled to move along the longitudinal direction of the decontamination area 2a. Therefore, the laser light emitted from the laser head 212d moves in a zigzag pattern along the longitudinal direction of the tray 2d, as shown in FIG. 7(a), and decontaminates the underside of the metal-contaminated waste placed on the tray 2d. Note that, for ease of explanation, the illustration of the metal-contaminated waste has been omitted from FIG. 7(a).

Next, a method of using the laser decontamination system 1 will be described. First, the decontamination unit 2 and the ventilation unit 3 are transported individually by a transport truck or the like to the site where the decontamination treatment will be performed, with the duct 4 removed. The duct 4 is transported, for example, housed in a container constituting the decontamination unit 2 or the ventilation unit 3. Thereafter, the duct 4 is connected to the decontamination unit 2 and the ventilation unit 3, as shown in FIG. 1.

Metal contaminated waste cut on-site is placed on trays 2d placed on a transport cart 2f. As shown in FIG. 1, the transport cart 2f moves under its own power from the open opening and closing door 2k of the container into the work area 2b. At this time, the airtight door 2c is open, and the transport cart 2f that has moved into the work area 2b stops at a position where the trays 2d can be handed over to the guide rails 2e in the decontamination area 2a. The trays 2d are then transferred to the guide rails 2e in the decontamination area 2a.

After the desired tray 2d is placed on the guide rail 2e in the decontamination area 2a, the airtight door 2c is closed as shown in FIG. 2. The decontamination process is started by an operator in the work area 2b operating the control/operation panel 2m. At the same time, the suction blower 32 is operated, and the air in the decontamination area 2a is drawn into the exhaust duct 41 and sent to the filter device 31.

The laser decontamination device 21 decontaminates the metal-contaminated waste while moving on the guide rail from the back of the container toward the airtight door 2c. The first laser decontamination device 211 and the second laser decontamination device 212 may be operated individually or synchronously. The laser decontamination device 21 may perform decontamination processing only on the outward journey on the guide rail, or may perform decontamination processing on both the outward journey and the return journey. Depending on the condition of the metal-contaminated waste, the laser decontamination device 21 may be made to go back and forth multiple times to perform decontamination processing.

When the decontamination of the metal-contaminated waste is finished, the tray 2d is transferred to the transport cart 2f. The transport cart 2f transports the tray 2d from the decontamination unit 2 to a designated location, and the metal-contaminated waste is moved from the tray 2d to another transport means by a worker.

According to the laser decontamination system 1 of this embodiment described above, by dividing the decontamination unit 2 and ventilation unit 3 into separate containers, the decontamination equipment can be easily transported and decontamination treatment can be performed at the desired location, making the system automated and mobile, and improving work efficiency. In addition, by adopting a laser decontamination method for the decontamination equipment and performing decontamination treatment in the closed space of the decontamination area 2a, the amount of secondary waste generated can be reduced and the spread of contaminants can be suppressed.

The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the present invention.

1 Laser decontamination system 2 Decontamination unit 2a Decontamination area 2b Work area 2c Airtight door 2d Tray 2e Guide rail 2f Transport cart 2g Relay terminal box 2h Laser oscillator storage box 2i Surveillance camera 2j Lighting 2k Opening and closing door 2m Control and operation panel 2n Opening 2p Groove 2q Support member 2r Roller 2s Receiver 2t Sending device 2u, 2v Bottom surface 3 Ventilation unit 4 Duct 21 Laser decontamination device 21a First guide rail 21b Second guide rail 31 Filter device 32 Suction blower 33 Exhaust nozzle 34 Air supply filter 41 Exhaust duct 42 Air supply duct 211 First laser decontamination device 212 Second laser decontamination device 211a, 212a Travel cart 211b, 212b Laser irradiation unit 211c, 212c Surveillance camera 211d, 212d Laser head 211e Distance sensor 211f Guide rail 212e Base 212f, 212g Inclined surface

Claims (2)

A decontamination unit including a container housing a laser decontamination device capable of decontaminating metal contaminated waste;
A ventilation unit including a container housing a filter device capable of collecting contaminants generated by the use of the laser decontamination device;
A plurality of ducts configured to circulate air between a decontamination area of the decontamination unit and the ventilation unit and to be detachable;
A tray having a lattice shape and a plurality of openings on which the metal-contaminated waste is placed;
A transport cart that moves the tray within the decontamination unit,
The laser decontamination apparatus includes a first laser decontamination apparatus capable of decontaminating the upper surface of the metal-contaminated waste placed on the tray in the decontamination area, and a second laser decontamination apparatus capable of decontaminating the lower surface of the metal-contaminated waste placed on the tray in the decontamination area by irradiating laser light from an opening of the tray ;
The first laser decontamination apparatus includes a laser irradiation unit configured to be movable along the longitudinal direction of the decontamination area and to be movable in the vertical direction according to the height of the metal-contaminated waste placed on the tray ;
The second laser decontamination apparatus includes a laser irradiation unit configured to be movable along the longitudinal direction of the decontamination area and to be movable in a direction parallel to the bottom surface of the tray and perpendicular to the longitudinal direction ,
A laser decontamination system comprising: The groove of the tray is a complex structure formed along the longitudinal direction by a frame formed in a mountain shape. The second laser decontamination device is provided with a plurality of grooves, and the second laser decontamination device is provided with a plurality of grooves on the bottom surface of the tray. A laser irradiation unit in the front row is configured to be movable diagonally in the direction of the tray. A rear row of laser irradiation units configured to be movable diagonally with respect to the other surface of the bottom surface. The laser decontamination system of claim 1 .