Decontamination device, decontamination line

Abstract

To improve the environment for a decontamination work and decontaminate a workpiece more evenly than decontaminating a workpiece manually.SOLUTION: A decontamination device 300 includes: a blast box 350; a conveyance unit 400 for conveying a workpiece from an entrance to an exit of the blast box 350; a blast head 500 having a blast nozzle for emitting a blast material B; a connection unit 600 located in the upper part of the blast box 350, the connection unit connecting the blast head 500 to the blast box 350; and a connection unit 700 attached in the bottom part of the blast box 350, a hose for sucking the blast material B being connected to the connection unit 700. The connection unit 600 has an air passage unit 650 for drawing outside air into the blast box 350, in association with emission of the blast material B by the blast head 500.SELECTED DRAWING: Figure 28

Description

Technical Field

[0001] The present invention relates to a technique for decontaminating a workpiece.

Background Art

[0002] In the decommissioning work of nuclear power plants, when discarding metal pipes used in heat exchangers etc., after processing the pipes into a plate shape, decontamination is carried out by air blasting. As a document disclosing a technique related to the decontamination of metal materials, there is Patent Document 1.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Conventionally, a splash prevention cover was installed, and within it, workers manually carried out decontamination work by air blasting. The problems with the conventional decontamination work were that it was in a poor environment in a dust atmosphere and it was difficult to decontaminate the workpiece evenly because it was manual work. An object of this invention is to provide a decontamination device that improves the environment of the decontamination work and can decontaminate the workpiece more evenly than manual work.

Means for Solving the Problems

[0005] The decontamination device includes a blast box, a conveying unit that conveys a workpiece from the inlet to the outlet of the blast box, a blast head having a blast nozzle that emits a blast material, a connecting portion located above the blast box for connecting the blast head to the blast box, and a connection portion attached to the bottom of the blast box to which a suction hose for sucking the blast material is connected. The connecting portion has a ventilation portion that takes in outside air into the blast box as the blast material is emitted by the blast head.

[0006] With this configuration, it is possible to suppress the scattering of dust contaminated with blast materials (scouring materials) and radioactive substances to the surroundings, enabling work in a good working environment. The surface of the workpiece can be decontaminated evenly compared to manual work. Continuous decontamination is possible, and the work efficiency is higher than that of manual work. The occupied space of the decontamination device is small, and it can be used even in a narrow workplace.

[0007] As an embodiment of the decontamination device, the ventilation portion may be arranged so as to surround the entire circumference of the blast head.

[0008] As an embodiment of the decontamination device, the connecting portion may include a gantry fixed to the ceiling wall of the blast box and having a through hole penetrating vertically, a fixing plate having an annular holding member for holding the blast head, a columnar boss portion that receives the lower surface of the fixing plate at a position a predetermined distance away from the gantry, and an outer wall portion provided along the outer circumference of the fixing plate and surrounding the sides of the blast head and the boss portion between the fixed wall and the ceiling wall. The blast nozzle may penetrate through the through hole of the fixing plate so that the nozzle tip for emitting the blast material faces into the through hole of the gantry. The outer wall portion may be made of a brush and function as a ventilation portion for taking in outside air into the through hole of the gantry as the blast material is emitted by the blast head.

[0009] As an embodiment of the decontamination device, the gantry may have an annular peripheral wall. Further, the lower end of the outer wall portion made of the brush may be fitted inside the peripheral wall of the gantry.

[0010] As an embodiment of the decontamination device, the blast box may be configured to have a rubber protective layer on its inner surface.

[0011] The decontamination device disclosed in this specification can be used for decontaminating contaminated pipes. Further, the decontamination device can be used not only for decontaminating pipes but also for decontaminating other workpieces.

Effect of the Invention

[0012] According to the present invention, the working environment of the decontamination operation can be improved, and the workpiece can be decontaminated evenly compared to manual work.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

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Figure 7

Figure 8

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Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

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Figure 20

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Figure 22

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Figure 24

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Figure 28

Mode for Carrying Out the Invention

[0014] <Embodiment> Embodiments of the present invention will be described with reference to Figs. 1 to 28. When performing the decommissioning work of a nuclear power plant, it is necessary to remove and disassemble metal pipes (hereinafter referred to as thin pipes) from high-pressure feedwater heaters and condensers. This embodiment uses the "decontamination device 300" in the decontamination line L of the thin pipe 1 removed from a high-pressure feedwater heater or a condenser.

[0015] 1. Decontamination operation procedure for the thin pipe 1 Fig. 1 is a process diagram of the decontamination operation of the thin pipe 1. The decontamination operation is carried out through the following steps. (a) Step of cutting out the straight pipe portion of the thin pipe 1 from the heat exchanger or the condenser (b) Step of cutting the cut-out thin pipe 1 to a certain length (c) Step of splitting the thin pipe 1 cut to a certain length in half (d) Step of rolling the half-cut thin tube 1 into a flat plate shape (e) Step of decontaminating the thin tube 1 rolled into a flat plate shape

[0016] (a) - (e) By these steps, the removed thin tube 1 can be decontaminated and can be treated as waste. Note that reference numeral 1A is the thin tube after half-cutting, reference numeral 1B is the thin tube after rolling, and reference numeral 1C is the thin tube after decontamination.

[0017] In this embodiment, as shown in FIG. 2, the decontamination line L is composed of three devices: a cutting device 10, a rolling device 100, and a decontamination device 300, and the steps (c) - (e) can be performed by a flow operation. Note that reference numeral U indicates the working space of the operator.

[0018] Hereinafter, the cutting device 10, the rolling device 100, and the decontamination device 300 will be described in order. Also, the direction is such that the conveying direction of the thin tube 1 is the X direction, the direction orthogonal to the X direction is the Y direction, and the vertical direction is the Z direction.

[0019] 2. Description of the cutting device 10 FIG. 3 is a side view of the cutting device 10, FIG. 4 is a plan view of the cutting device 10, and FIG. 5 is a perspective view of the main part of the cutting device 10.

[0020] The cutting device 10 includes a stepped workbench 11, a cutting device main body 15, a drive motor 70, a first roller conveyor 16, and a second roller conveyor 17.

[0021] As shown in FIGS. 4 and 5, the cutting device main body 15 and the drive motor 70 are separately arranged on the first upper surface wall 11A and the second upper surface wall 11B of the workbench 11.

[0022] The first roller conveyor 16 is located on the right side surface (introduction surface) of the cutting device main body 15, and the second roller conveyor 17 is located on the left side surface (discharge surface) of the cutting device main body 15.

[0023] The cutting device main body 15 is a device that cuts the thin tube 1 into two with a cutting plane parallel to the axis V of the thin tube 1 using a shaft rod 3.

[0024] As shown in Fig. 6, the shaft bar 3 is a bar longer than the pipe 1. The shaft bar 3 has a circular cross-section and is inserted and used inside the pipe 1. The shaft bar 3 is used to prevent the pipe 1 from deforming inward and escaping during cutting by the rotary blades 50A and 50B.

[0025] As shown in Figs. 7 and 8, the cutting device main body 15 includes a main body frame 20, a pair of rails 28A and 28B, a pair of conveying rollers 40A and 40B, a pair of roller holders 45A and 45B, a pair of rotary blades 50A and 50B, a pair of rotary blade holders 55A and 55B, a pair of guide members 60, and a gear mechanism 75.

[0026] The main body frame 20 is composed of a base 21, a pair of side panels 24, and a top plate 25. The pair of rails 28A and 28B are fixed to the inner surfaces of the pair of side panels 24. The pair of rails 28A and 28B extend parallel to the X direction and fix both front and rear ends to the front and rear frames 29. The pair of rails 28A and 28B are located at approximately the middle height of the main body frame 20 in the Z direction (vertical direction). The space between the rails is the conveying path of the pipe 1.

[0027] Between the two side panels 24, a pair of conveying rollers 40A and 40B and a pair of rotary blades 50A and 50B are arranged.

[0028] The pair of conveying rollers 40A and 40B face each other in the Z direction (vertical direction). Each conveying roller 40A and 40B is supported by roller holders 45A and 45B.

[0029] The roller holders 45A and 45B are U-shaped in cross-section, and the two side walls located on both sides of the conveying rollers 40A and 40B rotatably support the shaft portions 41 of the respective conveying rollers 40A and 40B.

[0030] The pair of conveying rollers 40A and 40B rotate by the power of the drive motor 70, and can send out the pipe 1 with the shaft rod 3 inserted therein along the conveying path located between the two rails 28 to the downstream cutting position.

[0031] The pair of rotary blades 50A and 50B are arranged on the downstream side of the pair of conveying rollers 40A and 40B. Specifically, they are arranged at the cutting position on the conveying path. The pair of rotary blades 50A and 50B face each other in the vertical direction (Z direction). Each rotary blade 50A and 50B is supported by rotary blade holders 55A and 55B. The rotary blade holders 55A and 55B are U-shaped in cross section, and the two side walls 57 located on both sides of the rotary blade 50 rotatably support the shaft portions 51 of the rotary blades 50A and 50B.

[0032] As shown in FIGS. 7 and 8, the gear mechanism 75 includes a first gear G1, a second gear G2, a third gear G3, a fourth gear G4, a fifth gear G5, a sixth gear G6, a seventh gear G7, and an eighth gear G8. The first gear G1 and the second gear G2 are arranged on the front side of the main body frame 20.

[0033] The first gear G1 is fixed to the end of the shaft portion 41 of the lower conveying roller 40B, and the second gear G2 is fixed to the end of the shaft portion 41 of the upper conveying roller 40A. The first gear G1 and the second gear G2 are meshed with each other, and the first gear G1 is also meshed with the motor gear 73.

[0034] From the above, by transmitting the power of the drive motor 70 to the two conveying rollers 40A and 40B through the respective gears 73, G1, and G2, the two conveying rollers 40A and 40B can be rotated.

[0035] The third gear G3 to the eighth gear G8 are arranged on the back side of the main body frame 20. The third gear G3 is fixed to the end of the shaft portion 41 of the lower conveying roller 40B, and the fifth gear is fixed to the end of the shaft portion 51 of the lower rotary blade 50B. The fourth gear G4 is engaged between the third gear G3 and the fifth gear G5 and meshes with both gears. The fourth gear G4 is an idle gear for transmitting power between the gears.

[0036] The sixth gear G6 is fixed to the end of the shaft portion 41 of the upper conveying roller 40A, and the eighth gear G8 is fixed to the end of the shaft portion 51 of the upper rotary blade 50A. The seventh gear G7 meshes with both the sixth gear G6 and the eighth gear G8 and is disposed therebetween. The seventh gear G7 is an idler gear for transmitting power between gears.

[0037] From the above, by transmitting the power of the drive motor 70 to the two rotary blades 50A and 50B via the respective gears G3 to G8, it is possible to rotate not only the two conveying rollers 40A and 40B but also the two rotary blades 50A and 50B.

[0038] When cutting the thin tube 1, first, the start switch installed on the workbench 11 is operated to drive the drive motor 70. By driving the drive motor 70, the two conveying rollers 40A and 40B and the two rotary blades 50A and 50B rotate respectively.

[0039] Next, the shaft rod 3 is inserted into the thin tube 1 on the first roller conveyor 16, and then the pipe 1 into which the shaft rod 3 has been inserted is inserted between the two rotating conveying rollers 40A and 40B from the front of the cutting device main body 15.

[0040] When the pipe 1 into which the shaft rod 3 has been inserted is inserted up to the conveying rollers 40A and 40B, it is sent in the X direction along the conveying path by the two conveying rollers 40A and 40B.

[0041] The thin tube 1 moving along the conveying path is cut at the upper and lower ends of the outer circumference by the two rotating rotary blades 50A and 50B and divided into two parts left and right. Then, together with the shaft rod 3, the thin tube 1A divided into two parts left and right is discharged from the main body frame 20 onto the second roller conveyor 17.

[0042] 3. Description of the rolling device 100 FIG. 10 is a side view of the rolling device 100, FIG. 11 is a plan view of the rolling device 100, and FIG. 12 is a perspective view of a main part of the rolling device 100.

[0043] The rolling device 100 includes a workbench 110, a rolling device main body 120, a drive motor 170, a work guide 113, and a roller conveyor 115.

[0044] As shown in FIGS. 11 and 12, the rolling device main body 120 and the drive motor 170 are arranged on the upper surface wall 110A of the workbench 110.

[0045] As shown in FIG. 11, the work guide 113 is located on the left side surface (introduction surface) of the rolling device main body 120, and the roller conveyor 115 is located on the right side surface (discharge surface) of the rolling device main body 120.

[0046] The rolling device main body 120 is a device that rolls the thin tube 1A divided into two parts by the cutting device 10 into a flat plate shape.

[0047] As shown in FIG. 12, the rolling device main body 120 has an introduction part 121 and a main body frame 130.

[0048] The main body frame 130 is composed of a lower frame 131 and an upper frame 135, and four stages of rolling rollers 150A to 150D are arranged in the X direction inside (see FIG. 13).

[0049] As shown in FIGS. 14 and 15, the rolling roller 150 is composed of a lower roller 151 and an upper roller 155. The lower roller 151 and the upper roller 155 are made of metal. The lower rollers 151A to 151D from the first stage to the fourth stage are supported in a two-supported state by two roller guides 132 and 133 fixed to the lower frame 131.

[0050] The roller widths of the lower rollers 151A to 151D become wider in the order of the first stage, the second stage, and the third stage, and the third stage and the fourth stage have the same width.

[0051] On one hand, the upper rollers 155A to 155D in the first to fourth stages are supported in a both-end supported state by a roller guide 137 having a U-shaped cross-section fixed to the upper frame 135. Four roller guides 137 are provided corresponding to the four upper rollers 155A to 155D. In FIG. 14, the roller guide 137 is L-shaped, but a part of the wall is omitted to show the rollers.

[0052] The roller widths of the upper rollers 155A to 155D are the same from the first stage to the fourth stage, and are wide (the same width as the lower rollers 151C and 151D in the third and fourth stages).

[0053] The rolling device main body 120 has a gear mechanism 160. The gear mechanism 160 includes first to eighth gears G1 to G8. The first gear G1 is disposed on the back side of the lower frame 131 (see FIG. 16). The first gear G1 meshes with the motor shaft of the drive motor 170.

[0054] As shown in FIG. 13, the second to eighth gears G2 to G8 are disposed on the front side of the roller guide 132. The second gear G2 is fixed to the shaft end of the roller shaft of the first-stage lower roller 151A, and the fourth gear G4 is fixed to the shaft end of the roller shaft of the second-stage lower roller 151B. The fourth gear G4 is a main gear coaxial with the first gear G1, that is, the first gear G1 is fixed to one side of the roller shaft of the second-stage lower roller 151B, and the fourth gear G4 is fixed to the other side.

[0055] The sixth gear G4 is fixed to the shaft end of the roller shaft of the third-stage lower roller 151C, and the eighth gear G8 is fixed to the shaft end of the roller shaft of the fourth-stage lower roller 151D.

[0056] The third gear G3 meshes with both the second gear G2 and the fourth gear G4 in between. The third gear G3 is an idler gear for transmitting power between gears. The fifth gear G5 and the seventh gear G7 are also idler gears for transmitting power between gears.

[0057] From the above, the power of the drive motor 170 can be transmitted to each of the lower rollers 151A to 151D via the respective gears G1 to G8.

[0058] When rolling the capillary tube 1A cut into two pieces, first, the start switch of the workbench 110 is operated to drive the drive motor 170. By driving the drive motor 170, each of the lower rollers 151A to 151D rotates.

[0059] Next, the capillary tube 1A on the work guide 113 is inserted into the introduction part 121 while turning the cut surface upward. When the tip of the capillary tube 1A reaches the first-stage rolling roller 150A, the capillary tube 1A is sandwiched from above and below by the two rollers 151 and 155 and is sequentially sent to the subsequent rolling rollers 150B to 150D.

[0060] The capillary tube 1A is corrected for curvature in the cross-sectional direction and rolled into a flat plate shape by the respective stage rolling rollers 150A to 150D. Then, the capillary tube 1B rolled into a flat plate shape is discharged from the rolling device main body 120 onto the roller conveyor 115.

[0061] 4. Description of the decontamination device 300 FIG. 17 is a side view of the decontamination device 300, FIG. 18 is a plan view of the decontamination device 300, and FIGS. 19 and 20 are perspective views of the main part of the decontamination device 300.

[0062] The decontamination device 300 includes a workbench 310, a decontamination device main body 320, a work guide 313, and a roller conveyor 315.

[0063] As shown in FIGS. 18 and 19, the decontamination device main body 320 is disposed on the upper surface wall 310A of the workbench 310.

[0064] As shown in FIG. 18, the work guide 313 is located on the left side surface (introduction surface) of the decontamination device main body 320, and the roller conveyor 315 is located on the right side surface (discharge surface) of the decontamination device main body 320.

[0065] The decontamination device main body 320 is a device for decontaminating the surface of the thin tube 1B rolled into a flat plate shape by the rolling device 100.

[0066] As shown in FIG. 20, the decontamination device main body 320 includes a base plate 330, a blast box 350, a conveying unit 400, a blast head 500, a connecting unit 600, and a connecting portion 700.

[0067] The base plate 330 is for fixing to the workbench 310. A through hole for passing the blast material B is formed in the central portion of the base plate 330.

[0068] The blast box 350 is box-shaped with an open bottom, and is composed of four side walls 360A to 360D and a ceiling wall 370. A through hole 371 is provided in the central portion of the ceiling wall 370 (see FIG. 27). The first side wall 360A and the second side wall 360C face each other, and the third side wall 360B and the fourth side wall 360D face each other. In FIGS. 20 and 21, the reference numerals of the second side wall 360C and the fourth side wall 360D are omitted.

[0069] A flange 355 is provided at the bottom of the blast box 350. The blast box 350 is fixed to the base plate 330 via the flange 355.

[0070] The first side wall 360A of the blast box 350 is the work introduction surface, and the second side wall 360C is the work discharge surface. The first side wall 360A has an opening (entrance) for introducing the work, and the second side wall 360C has an opening (exit) for discharging the work.

[0071] The conveying unit 400 is composed of a first conveying unit 400A and a second conveying unit 400C. The first conveying unit 400A is in front of the first side wall 360A, and as shown in FIGS. 20 and 21, includes a roller panel 405, a movable plate 408, a first roller 410, a second roller 420, and a drive motor 450.

[0072] As shown in Fig. 21, the roller panel 405 is L-shaped and fixed in front of the first side wall 360A. The movable plate 408 is supported so as to be vertically movable with respect to the upper surface wall 407 of the roller panel 405 via shaft pins 407A and 407B. A coil spring 409 is provided between the upper surface wall 407 and the movable plate 408. The coil spring 409 biases the movable plate 408 downward.

[0073] The first roller 410 is fixed to the front wall of the roller panel 405 via the first roller holder 415. The second roller 420 is fixed to the movable plate 408 via the second roller holder 425. The second roller 420 is a movable roller that can move in the vertical direction. The two rollers 410 and 420 face each other vertically. The second roller 420 is biased by the coil spring 409 so as to contact the first roller 410.

[0074] As shown in Fig. 22, the drive motor 450 is attached below the first roller 410. A first gear G1 is attached to the motor shaft of the drive motor 450. The first gear G1 meshes with a second gear G2 fixed to the shaft end of the first roller, and the second gear G2 meshes with a third gear G3 fixed to the shaft end of the second roller.

[0075] From the above, the power of the drive motor 450 can be transmitted to the first roller 410 and the second roller 420 via the respective gears G1 to G3. The structure of the second conveying unit 400C is the same as the structure of the first conveying unit 400A. In addition, sensors S1 and S2 for detecting the thin tube 1B are provided in the first conveying unit 400A and the second conveying unit 400C, respectively (see Fig. 23).

[0076] As shown in Fig. 23, a work introduction part 380A is provided between the first conveying unit 400A and the first side wall 360A, and a work discharge part 380B is provided between the second conveying unit 400C and the second side wall 360C.

[0077] The work introduction part 380A has an inlet for the capillary tube 1B. A brush 383 and a guide roller 385 are provided at the inlet. The brush 383 prevents the contaminants decontaminated from the capillary tube 1B from leaking to the outside from the inlet. The guide roller 385 is for guiding the capillary tube 1B.

[0078] The work discharge part 380C has substantially the same structure as the work introduction part 380A. The work discharge part 380C has an outlet for the capillary tube 1B. A brush 383 and a guide roller 385 are provided at the outlet. The brush 383 prevents the contaminants decontaminated from the capillary tube 1B from leaking to the outside from the outlet. The guide roller 385 is for guiding the capillary tube 1B.

[0079] As shown in FIGS. 23 and 28, a blast head 500 is attached to the ceiling wall 370 of the blast box 350 via a connecting part 600. The blast head 500 has a cylindrical shape with an axially penetrating hole 500A, and a blast nozzle 510 is attached to the tip. The blast nozzle 510 has a thin cylindrical tip part and has a nozzle hole 511 along the axis. The nozzle hole 511 communicates with the axially penetrating hole 500A of the blast head 500, and the blast material B is ejected from the nozzle tip through the axially penetrating hole 500A and the nozzle hole 511.

[0080] The blast head 500 is connected to an air blast device 550 via a blast hose 530. The air blast device 550 is a device for injecting the blast material B (scouring material) (see FIG. 24). The air blast device 550 can be of a direct pressure type or a vacuum type.

[0081] The direct pressure type is a type that sends compressed air into a blast tank 560 containing the blast material B, mixes the blast material B and the compressed air at the lower part of the tank, and injects the blast material B together with the compressed air at a high pressure.

[0082] The vacuum type blows compressed air from a nozzle like a spray, sucks up the blasting material B by the ejector effect, and mixes the blasting material B with the blown compressed air.

[0083] In this embodiment, a direct pressure type with excellent grinding power is used. The blasting material B is made of alumina, but alternatively, iron-based (such as steel shot, steel grid, reduced iron powder, etc.), plastic-based (such as polyplus, polyextura, nylon, etc.), or plant-based (such as walnut, peach, corn, etc.) materials can also be used.

[0084] Also, in this embodiment, as shown in FIG. 23, a rubber protective layer 365 is provided on the inner surface of the blast box 350. The protective layer 365 is provided on the inner four sides of the blast box 350. By providing the protective layer 365, the blast box 350 can be protected from the blasting material B and wear of the inner surface can be suppressed.

[0085] As shown in FIGS. 25 to 27, the connecting portion 600 includes a gantry 610, a fixing plate 620, a boss portion 630, and four outer wall portions 650A to 650D.

[0086] The gantry 610 is made of metal and is fixed to the ceiling wall 370 of the blast box 350. The gantry 610 has a quadrangular shape in plan view and has a through hole 611 at the center. Further, four peripheral walls 615A to 615D are provided on the gantry 610, surrounding the entire circumference.

[0087] The fixing plate 620 is a square metal plate. An annular holding member 625 is provided at the central portion of the fixing plate 620. Bolt holes 627 are formed in the holding member 625. The bolt holes 627 are provided so as to penetrate from the outer peripheral surface to the inner peripheral surface of the holding member 625.

[0088] The boss portion 630 is cylindrical and is provided at four locations corresponding to the four corners of the fixing plate 620. The boss portion 630 is located between the gantry 610 and the fixing plate 620 and supports the fixing plate 620 at a position separated from the gantry 610 by the height of the boss portion 630.

[0089] As shown in FIG. 26, the four outer wall portions 650A to 650D are composed of a metal base portion 660 and a brush portion 670. The brush portion 670 is made of brush hairs made of synthetic fiber, metal fiber or natural fiber and is fixed to the base portion 660. The four outer wall portions 650A to 650D are respectively fixed to the four side surfaces of the fixing plate 620 with bolts via fasteners 680.

[0090] As shown in FIG. 27, the fixing plate 620, the boss portion 630, and the gantry 610 are fixed to the ceiling wall 370 by bolts B that penetrate through them vertically.

[0091] Also, in this embodiment, a rubber spacer 375 is interposed between the gantry 610 and the ceiling wall 370 to eliminate the gap between them and enhance the adhesion.

[0092] As shown in FIG. 28, the blast head 500 has a stepped portion 501 at its tip. By fitting the stepped portion 501 into the holding member 625, the blast head 500 can be positioned in the axial direction (vertical direction). Then, by inserting and tightening a bolt BS into the bolt hole 627, the blast head 500 can be prevented from coming off the holding member 625.

[0093] The blast nozzle 510 penetrates through the fixing plate 620, and the nozzle tip 510A for ejecting the blast material B faces into the through hole 611 of the gantry 610.

[0094] The outer wall portions 650A to 650D surround the entire circumference around the blast nozzle 510. Since the outer wall portions 650A to 650D are made of brush, when the blast nozzle 510 injects the blast material B at high pressure, outside air is taken into the inside of the gantry 610 through the outer peripheral walls 650A to 650D, and an air flow directed downward is generated in the blast box (FIG. 28).

[0095] Further, the lower end portion 651 of the outer wall portion 650 is fitted inside the peripheral wall 615 of the gantry 610, and the outer wall portion 650 overlaps the gantry 610 by the height of the peripheral wall 615.

[0096] By doing so, the gap between the outer wall portion 650 and the gantry 610 can be made small, and it becomes difficult for contaminants to leak to the outside.

[0097] The connection portion 700 is a tubular joint and is flange-coupled to the lower surface of the base plate 330. The connection portion 700 communicates with the inside of the blast box 350 through the through hole 331 of the base plate 330.

[0098] The inner diameter of the connection portion 700 becomes smaller from the upper part to the lower part. A suction hose 750 for sucking the blast material B is flange-coupled to the tip of the connection portion 700. A vacuum device (not shown) is connected to the hose 750, and the blast material B in the blast box 350 can be recovered.

[0099] When decontaminating the rolled plate (thin tube) 1B rolled flat, first, the start switch of the workbench 310 is operated to drive the drive motor 450. By driving the drive motor 450, the rollers 410 and 420 of the first conveying portion 400A and the second conveying portion 400B rotate.

[0100] Next, the rolled plate (thin tube) 1B on the work guide 313 is inserted between the rollers 410 and 420 of the first transport unit 400A with the surface to be decontaminated (inner surface of the tube) facing upward. When the tip of the rolled plate (thin tube) 1B reaches between the rollers, the rolled plate (thin tube) 1B moves inside the blast box 350 while being sandwiched from above and below by the two rollers 410 and 420.

[0101] While the rolled plate (thin tube) 1B is moving in the blast box 350, the blast material B is high-pressure jetted from the blast head 500 onto the surface of the rolled plate (thin tube) 1B, thereby removing the surface contaminants. The decontaminated rolled plate (thin tube) 1C is discharged from the second transport unit 400B onto the roller conveyor 315.

[0102] As described above, by using the decontamination line L, the following three operations can be performed in a flow operation, resulting in good workability. (1) The operation of cutting the thin tube 1 into two in a plane horizontal to the tube axis V (2) The operation of rolling the two cut thin tubes 1A into a flat state (3) The operation of decontaminating the rolled plate 1B (thin tube)

[0103] 5. Explanation of Effects With this configuration, it is possible to suppress the scattering of the blast material B (scouring material) and the dust contaminated with radioactive substances to the surroundings, enabling work in a good working environment. Also, continuous decontamination is possible, and the work efficiency is higher compared to manual work. The occupied space of the decontamination device 300 is small, and it can be used even in a narrow workplace.

[0104] Further, since the decontamination device 300 has a configuration (outer wall portion made of brush) that takes in outside air into the blast box 350 as the blast material B is ejected from the blast nozzle 510, it is difficult for turbulent flow to occur inside the blast box 350. Therefore, as shown in Fig. 23, the blast material B can be evenly ejected onto the surface of the rolled plate (thin tube 1), and the surface of the rolled plate (thin tube 1) can be evenly decontaminated.

[0105] As shown in FIG. 23, the decontamination device 300 is provided with a rubber protective layer 365 on the inner surface of the blast box 350. By providing the protective layer 365, the blast box 350 can be protected from the blast material B, and wear of the inner surface can be suppressed.

[0106] The conveying unit 400 includes a first roller 410 and a second roller 420. Since the first roller 410 is fixed and the second roller 420 is movable (vertically movable), even if there are variations in the plate thickness of the rolled material (thin tube 1B), the difference in plate thickness can be absorbed. Therefore, it is difficult for conveyance failure of the rolled material to occur, and the decontamination operation can be performed efficiently.

[0107] <Other Embodiments> The present invention is not limited to the embodiments described above with reference to the description and drawings. For example, the following embodiments are also included in the technical scope of the present invention.

[0108] (1) In the above embodiment, an example in which the decontamination device 300 is used as part of the decontamination line L is shown, but it can also be used alone.

[0109] (2) In the above embodiment, the decontamination device 300 is used for decontamination of the thin tube 1, but it may be used for decontamination of other workpieces other than the thin tube 1.

[0110] (3) In the above embodiment, the outer wall portion 650 is made of brush to provide air permeability, but air permeability may be provided by another method. For example, ventilation holes may be provided in the outer wall portion 650. Further, the ventilation holes may be provided in all of the outer wall portions 650A to 650D, or may be provided only in some of the outer wall portions 650A and 650C.

[0111] (4) In the above embodiment, the lower end portion 651 of the outer wall portion 650 is fitted inside the peripheral wall 615, but if it overlaps with the peripheral wall 615, it may be located outside the peripheral wall 615.

[0112] (5) In the above embodiment, the decontamination apparatus main body 320 is attached to the workbench 310 via the base plate 330, but the base plate 330 may be omitted.

[0113] (6) In the above embodiment, the decontamination line L is composed of the cutting device 10, the rolling device 100, and the decontamination device 300. The "cutting device" may have a structure other than the cutting device 10 as long as it is a device for cutting the contaminated pipe in a plane along the pipe axis. The "rolling device" may have a structure other than the rolling device 100 as long as it is a device for rolling the contaminated pipe divided into two parts by the cutting device into a horizontal plate. The "decontamination device" may be other than the decontamination device 300 as long as it is a device for decontaminating the surface of the plate rolled by the rolling device with the blasting material B.

[0114] (7) In the above embodiment, the decontamination line L is composed of the cutting device 10, the rolling device 100, and the decontamination device 300. A sizing cutter for cutting the thin pipe cut out from the heat exchanger to a certain length may be added in front of the cutting device 10.

Explanation of reference numerals

[0115] 1 Thin pipe 10 Cutting device 100 Rolling device 300 Decontamination device 350 Blasting box 500 Blasting head 510 Blasting nozzle 600 Connecting part 610 Mounting base 615 Peripheral wall base 620 Fixed plate 630 Boss part 650 Outer wall part (brush) 700 Connection part

Claims

1. A decontamination device comprising: a blast box; a conveying unit configured to convey a workpiece from an inlet to an outlet of the blast box; a blast head having a blast nozzle for ejecting a blast material; a connecting portion located above the blast box for connecting the blast head to the blast box; a connection portion attached to the bottom of the blast box to which a suction hose for sucking the blast material is connected, wherein the connecting portion has a ventilation portion for taking in outside air into the blast box as the blast material is ejected by the blast head; the ventilation portion is positioned so as to surround the entire circumference of the blast head, the decontamination device.

2. A decontamination device comprising: a blast box; a conveying unit configured to convey a workpiece from an inlet to an outlet of the blast box; a blast head having a blast nozzle for ejecting a blast material; a connecting portion located above the blast box for connecting the blast head to the blast box; a connection portion attached to the bottom of the blast box to which a suction hose for sucking the blast material is connected, wherein the connecting portion has a ventilation portion for taking in outside air into the blast box as the blast material is ejected by the blast head; the connecting portion includes: a pedestal fixed to the ceiling wall of the blast box and having a through hole penetrating vertically; a fixing plate having an annular holding member for holding the blast head; a columnar boss portion for receiving the lower surface of the fixing plate at a position spaced a predetermined distance from the pedestal; an outer wall portion provided along the outer periphery of the fixing plate and surrounding the side of the blast nozzle between the fixing plate and the ceiling wall; the blast nozzle penetrates through the through hole of the fixing plate and has a nozzle tip for ejecting the blast material facing into the through hole of the pedestal; the outer wall portion is made of a brush and functions as a ventilation portion for taking in outside air into the through hole of the pedestal as the blast material is ejected by the blast head, the decontamination device.

3. The decontamination device according to claim 2, wherein the pedestal has an annular peripheral wall; the lower end portion of the brush-made outer wall portion is fitted inside the peripheral wall of the pedestal, the decontamination device.

4. The decontamination device according to any one of claims 1 to 3, wherein the blast box has a rubber protective layer on its inner surface, the decontamination device.

5. A decontamination line for contaminated pipes, a cutting device that cuts the contaminated pipe in a plane along the pipe axis, a rolling device that rolls the contaminated pipe divided into two parts by the cutting device onto a horizontal plate, and a decontamination device that decontaminates the surface of the plate rolled by the rolling device with a blasting material, wherein the decontamination device is a decontamination line that is the decontamination device according to any one of claims 1 to 4.

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