JP6531533B2 - Decontamination equipment and decontamination method - Google Patents

Description

  The present invention relates to a decontamination apparatus and method for decontaminating a radioactively contaminated tank.

  After temporarily storing high concentration contaminated water generated at a nuclear power plant in a tank, if the high concentration contaminated water is transferred to another storage facility, the inner surface of the tank becomes radioactively contaminated . Therefore, when disassembling the tank, it is necessary to decontaminate the inner surface of the tank.

  Patent Document 1 discloses an apparatus for providing a worker with a work space when decontaminating the inner surface of a tank. Specifically, a rail is provided along the inner surface of the side plate of the tank at the top thereof, a trolley moving along the rail is provided on the rail, and a gondola is suspended from the trolley. Workers get on the gondola and decontaminate the inside of the tank side plate.

Japanese Utility Model Application Publication No. 3-12197

  However, in the technique described in Patent Document 1, since the worker works in the tank, the problem of the worker's exposure to radiation can not be avoided.

  The present invention has been made in view of the above circumstances. The problem to be solved by the present invention is to make it possible to decontaminate the inner surface of the tank without the operator entering the tank.

  In order to solve the above problems, in a decontamination facility for decontaminating the inner surface of a tank having a bottom and a side wall erected around the bottom, provided in the upper end of the side wall along the upper end of the side wall. An upper rail, a first upper mount moving along the upper rail, a second upper mount moving away from the first upper mount along the upper rail, and the side wall from the first upper mount A lifting rail hanging down along the inner surface of the lower part, a vertical member hanging down from the second upper mount along the inner surface of the side wall portion, a lifting mount moving up and down along the lifting rail, and a lower end of the lifting rail A lower rail constructed between the lower end of the vertical member, a lower gantry moving along the lower rail, and a side decontamination machine provided on the elevating gantry and decontaminating the inner surface of the side wall portion; Provided on the lower gantry Characterized in that it and a bottom decontamination machine for decontaminating the bottom.

  Further, in the decontamination method for decontaminating the tank using the decontamination facility, movement of the first upper mount and the second upper mount along the upper rail, and the elevating mount along the elevating rail Moving the side decontamination machine along the inner surface of the side wall portion in combination with the movement of the side wall portion while decontaminating the inner surface of the side wall portion with the side surface decontamination machine; The bottom decontamination machine is moved by the bottom decontamination machine while the bottom decontamination machine is moved along the bottom by a combination of the movement of one upper carriage and the second upper carriage and the movement of the lower carriage along the lower rail. It is characterized in that the bottom is decontaminated.

According to the above, the combination of the movement of the first upper mount and the second upper mount along the upper rail and the movement of the lift mount along the lift rail makes the side decontamination machine an inner surface of the side wall of the tank. It can be moved along. Therefore, even if the worker does not enter the tank, the inner surface of the side wall of the tank can be decontaminated by the side decontamination machine.
The bottom decontamination machine can be moved along the bottom of the tank by a combination of the movement of the first and second upper carriages along the upper rail and the movement of the lower carriage along the lower rail. Therefore, the bottom of the tank can be decontaminated by the bottom decontamination machine even if the worker does not enter the tank.

Preferably, the decontamination facility further includes an upper decontamination machine provided at an upper end of the vertical member or the elevating rail and decontaminating an upper end portion of an inner surface of the side wall portion.
According to the above, even if the side decontamination machine can not be moved to the upper end of the inner surface of the side wall of the tank, the upper decontamination machine may be used to decontaminate the upper end of the inner surface of the side wall of the tank it can.

Preferably, the decontamination apparatus further includes a lower decontamination apparatus provided at the lower end of the vertical member or the elevating rail and decontaminating the lower end of the inner surface of the side wall.
According to the above, even if the side decontamination machine can not be moved to the lower end of the inner surface of the side wall of the tank, the lower decontamination machine may be used to decontaminate the lower end of the inner surface of the side wall of the tank it can.

Preferably, the decontamination facility further includes a side measuring instrument provided on the elevating platform and measuring a dose of the inner surface of the side wall portion.
According to the above, the combination of the movement of the first upper gantry and the second upper gantry along the upper rail and the movement of the elevator gantry along the elevator rail allows the side measuring instrument to be along the inner surface of the tank sidewall. Can be moved. Therefore, even if the worker does not enter the tank, the inner surface of the side wall of the tank can be scanned by the side measuring instrument to measure the dose distribution on the inner surface.

Preferably, the decontamination facility further comprises a lower measuring device provided at the lower mount and measuring the dose at the bottom.
According to the above, the lower measuring instrument is moved along the bottom of the tank by the combination of the movement of the first upper pedestal and the second upper pedestal along the upper rail and the movement of the lower pedestal along the lower rail. Can. Therefore, even if the worker does not enter the tank, the bottom of the tank can be scanned by the lower measuring instrument to measure the dose distribution at the bottom.

  According to the present invention, the inner surface of the tank can be decontaminated without the worker entering the tank, and the worker can be prevented from being exposed to radiation.

It is a perspective view of decontamination equipment. It is a piping diagram before operation of decontamination equipment. It is a schematic perspective view of the decontamination machine installed in the tank. It is a perspective view of an upper mount frame, a raising / lowering mount frame, a side decontamination unit, and a side dose measurement unit. It is a perspective view of a side decontamination unit. It is a perspective view of a lower mount, a bottom part decontamination unit, and a lower dose measurement unit. It is a perspective view of a bottom part decontamination unit. It is a perspective view of upper part decontamination machine. It is a perspective view of a lower decontamination machine. It is a piping diagram at the time of decontaminating the side wall part by spraying non-sublimation type | mold projection material on the side wall part of a tank. It is a piping diagram at the time of decontaminating the bottom part by spraying a non-sublimation type | mold projection material on the bottom part of a tank. It is a piping diagram at the time of decontaminating the side wall part by spraying a sublimation type projection material on the side wall part of a tank. It is a piping diagram at the time of decontaminating the bottom part by spraying a sublimation type projection material to the bottom part of a tank. It is a perspective view of the decontamination machine employ | adopted as the decontamination installation of a modification.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, since the embodiments described below are subject to various technically preferable limitations for practicing the present invention, the scope of the present invention is not limited to the following embodiments and illustrated examples.

1. Configuration of Decontamination Equipment FIG. 1 shows a decontamination equipment 1 for decontaminating a tank 5 in which contaminated water has been stored. FIG. 2 is a piping diagram before operation of the decontamination equipment 1. FIG. 3 shows the decontamination machine 2 installed in the tank 5.

  As shown in FIGS. 1 to 3, the decontamination facility 1 includes a work gantry 10 and a dust collector 3 installed beside the tank 5, various devices installed on the work gantry 10, and the tank 5. And the decontamination machine 2 installed in the

  As shown in FIG. 3, the tank 5 is an open top tank consisting of a circular bottom 6 and side walls 7 erected on the outer edge of the bottom 6. Here, high concentration contaminated water containing radioactive material was stored in the tank 5 before the construction of the decontamination facility 1, but the contaminated water is transferred to another storage facility, and the decontamination facility At the time of construction of 1, the tank 5 is empty. Since the inner surface of the tank 5 is contaminated with radioactive material, the inner surface of the tank 5 is decontaminated using this decontamination facility 1.

  A lid 9 is provided on the upper end of the tank 5. Here, the lid 9 is installed at the upper end of the tank 5 even before the decontamination equipment 1 is constructed. That is, when the contaminated water was stored in the tank 5, the top opening of the tank 5 was closed by the lid 9. The lid 9 is once removed from the tank 5, and after decontamination of the lid 9, the lid 9 is placed on the upper end of the tank 5 after the decontamination machine 2 is installed.

  As shown in FIG. 1, the work gantry 10 is installed beside the tank 5. A control and monitoring room 11 is installed on the work gantry 10. A control panel is provided in the control and monitoring room 11. The operator operates the control panel in the control and monitoring room 11 to operate the decontamination facility 1 and monitor the operating state of the decontamination facility 1.

  As shown in FIGS. 1 and 2, on the work gantry 10, the first projectile supply device 12, the second projectile supply device 13, the blast compressor 14, the suction compressor 15, the projectile recovery device 16, and cutting are performed. The waste collection device 17 and the dust collection device 18 are installed. As shown in FIG. 2, on the work gantry 10, connection ports 51b, 52b, 52d, 53c, 53e, 71b, 72b, 72d, 73c, 73e are provided which are used when the piping is refilled. . Connection ports 51 b, 52 b, 52 d, 53 d, 53 c, 53 e, 71 b, 72 b, 72 d, 73 c, 73 e, the first projectile supply device 12, the second projectiles, by performing piping replacement in accordance with the progress of the work. The path between the supply device 13, the blast compressor 14, the suction compressor 15, the projection material recovery device 16, the cutting debris recovery device 17 and the dust collector 18 is changed (see FIGS. 10 to 13).

  The first projectile supply device 12 is a solid non-sublimation projectile (for example, an iron projectile, a stainless steel projectile, a silicon carbide projectile, an amorphous projectile, a ceramic projectile, a zinc projectile Materials, aluminum-based projectiles, alumina-based projectiles, glass-based projectiles, etc.) are stored. And the 1st projection material supply apparatus 12 sends out the stored non-sublimation type | mold projection material. Although the details will be described later, the non-sublimation type projection material sent from the first projection material supply device 12 is sent to the decontamination nozzles 51 and 71 (see FIG. 2).

  In the second projectile supply device 13, a sublimation projectile (for example, dry ice) is stored. And the 2nd projection material supply apparatus 13 sends out the stored sublimation type projection material. Although the details will be described later, the sublimation projection material delivered from the second projectile supply device 13 is sent to the decontamination nozzles 52 and 72 (see FIG. 2).

  The first projectile supply device 12 and the second projectile supply device 13 are selectively used. That is, the second projectile supply device 13 is not used when the first projectile supply device 12 is used, and the first projectile supply device 12 is not used when the second projectile supply device 13 is used .

  Whichever of the first projectile supply device 12 and the second projectile supply device 13 is used, the compressor for blasting 14, the compressor for suction 15, the scrap collection device 17 and the dust collection device 18 are used. Moreover, the projection material collection | recovery apparatus 16 is used in the case of use of the 1st projection material supply apparatus 12, and in the case of use of the 2nd projection material supply apparatus 13, the projection material collection | recovery apparatus 16 is not used.

The blast compressor 14 and the suction compressor 15 compress air and deliver the compressed air.
The first projectile supply device 12 is connected to the projectile recovery device 16 by a pipe 16e (see FIG. 2). The projection material recovery device 16 recovers the non-sublimation type projection material contained in the air sent to the projection material recovery device 16 and sends the non-sublimation type projection material to the first projection material supply device 12 through the pipe 16 e. It is something to send out. For example, an air classification device can be used as the projection material collection device 16.

  The cutting waste collection device 17 is for collecting cutting waste contained in the air sent to the cutting waste collection device 17. Specifically, cutting waste collection device 17 has air classification device 17e and cutting waste storage part 17f, cutting waste in the air is separated by air classification device 17e, and separated cutting waste is stored in storage part 17f. Ru. The cuttings in the air sent to the cuttings collection device 17 are radioactive contaminants generated during the decontamination work of the tank 5.

  The cuttings collection device 17 is connected to the dust collection unit 18 by a pipe 17 g (see FIG. 2), and the air from which the cuttings have been removed is sent from the cuttings collection unit 17 to the collection collection unit 18. The dust collector 18 is constituted by a HEPA filter or the like, and the air sent from the cutting waste collection device 17 to the dust collector 18 is filtered by the dust collector 18 and dust in the air is collected in the dust collector 18 . The dust-collected air is discharged from the dust collector 18 to the atmosphere.

  Subsequently, the decontamination machine 2 installed in the tank 5 will be specifically described with reference to FIGS. 3 to 9. Here, FIG. 4 is a perspective view showing a part of the upper end portion of the side wall portion 7 of the tank 5 from inside and obliquely above. FIG. 5 is a partial cross-sectional perspective view showing the side decontamination unit 50 for decontaminating the side wall 7. FIG. 6 is a perspective view showing the bottom 6 of the tank 5 from diagonally above. FIG. 7 is a partially sectioned perspective view showing a bottom decontamination unit 70 for decontaminating the bottom 6. FIG. 8 is a perspective view showing the upper end portion of the inner surface of the side wall portion 7 from diagonally below. FIG. 9 is a perspective view showing an in-corner portion sandwiched by the side wall portion 7 and the bottom portion 6. In FIG. 3, the main parts of the decontamination machine 2 are made easy to see by omitting the illustration of the piping provided in the decontamination machine 2 and the illustration of the lid 9 installed on the tank 5.

  As shown in FIGS. 3 and 4, annular upper rails 21 and 22 and an annular tooth track 23 are installed at the upper end of the side wall 7 of the tank 5 along the circumferential direction of the side wall 7. The upper rails 21 and 22, the tooth track 23 and the side wall 7 are arranged concentrically, and the tooth track 23 is arranged between the inner upper rail 21 and the outer upper rail 22. A plurality of teeth are arranged along the circumferential direction on the outer peripheral surface of the tooth track 23.

  On the upper rails 21 and 22, a first upper mount 25 and a second upper mount 26 are provided so as to be able to travel along the upper rails 21 and 22. The first upper gantry 25 and the second upper gantry 26 are located radially opposite to each other across the center of the upper rails 21 and 22 therebetween.

  Turning motors 27 and 28 are attached to the upper mounts 25 and 26, respectively. Gears are provided on the shafts of the turning motors 27 and 28, respectively, and the gears mesh with the teeth of the tooth track 23. Accordingly, the upper mounts 25, 26 are pivoted along the upper rails 21, 22 and the tooth track 23 by the pivoting motors 27, 28. The turning motors 27 and 28 are synchronously controlled by the control panel of the control and monitoring room 11. Therefore, the start timings of the turning motors 27, 28 are synchronized, and the stopping timings of the turning motors 27, 28 are also synchronized, and the rotational speeds of the turning motors 27, 28 are equal to each other.

  The upper ends of two elevator rails 31 and 32 and tooth tracks 33 are attached to the first upper gantry 25, and the elevator rails 31 and 32 and tooth rails 33 are attached to the inner surface of the side wall portion 7 of the tank 5 from the first upper gantry 25. Hang vertically along the The elevating rails 31 and 32 and the tooth track 33 are provided in parallel with each other, and the tooth track 33 is disposed between the elevating rail 31 and the elevating rail 32. Further, the lift rails 31, 32 and the tooth track 33 are connected by a plurality of horizontal members (beams).

  As shown in FIG. 3, the upper end of the vertical member 30 is attached to the second upper gantry 26, and the vertical member 30 vertically hangs from the second upper gantry 26 along the inner surface of the side wall 7 of the tank 5. .

  As shown in FIGS. 3 and 6, two lower rails 41 and 42 and a tooth track 43 are provided in the side wall portion 7 between the lower ends of the lift rails 31 and 32 and the tooth track 33 and the lower end of the vertical member 30. It is spanned in the radial direction. Furthermore, the lower rails 41 and 42 and the tooth tracks 43 are provided upward from the bottom 6 of the tank 5 and parallel to the bottom 6. The lower rails 41 and 42 and the tooth track 43 are connected by a plurality of horizontal members (beams).

  As described above, by assembling the elevator rails 31, 32, the tooth rails 33, the lower rails 41, 42, the tooth rails 43, and the vertical member 30, their rigidity is improved. Therefore, when the upper mounts 25 and 26 turn along the upper rails 21 and 22, the lift rails 31 and 32, the tooth tracks 33, the lower rails 41 and 42, the tooth tracks 43 and the vertical members 30 move to the upper mounts 25 and 26. To follow the movement of the stable and turn.

  As shown in FIG. 3 and FIG. 4, the elevating racks 31, 32 are provided with elevating mounts 35 so as to be able to travel along the elevating rails 31, 32. A lifting motor 37 is attached to the lifting stand 35. A gear is provided on the shaft of the lifting motor 37, and the gear meshes with the tooth track 33. Therefore, the lifting platform 35 is lifted and lowered along the lifting rails 31 and 32 and the tooth track 33 by the lifting motor 37.

  As shown in FIGS. 4 and 5, the side decontamination unit 50 and the side dose measurement unit 60 are attached to the lifting and lowering stand 35 by brackets 38 and 39 respectively, and the side decontamination unit 50 and the lifting and lowering stand 35 And the side part dose measurement unit 60 is arranged in the circumferential direction of the side wall part 7 in these order. The side decontamination unit 50 is for removing radioactive substances attached to the inner surface of the side wall 7. The side dose measurement unit 60 is for measuring the dose of the inner surface of the side wall 7.

  As shown in FIGS. 3 and 6, the lower mounts 45 are provided on the lower rails 41 and 42 so as to be able to travel along the lower rails 41 and 42. A traverse motor 47 is attached to the lower mount 45. A gear is provided on the shaft of the traverse motor 47, and the gear meshes with the tooth track 43. Therefore, the lower mount 45 is moved radially along the lower rails 41 and 42 and the tooth track 43 by the traverse motor 47.

  As shown in FIGS. 6 and 7, a bracket 49 is suspended from the lower pedestal 45, a bottom decontamination unit 70 is attached to the side surface of the bracket 49, and a lower dose measurement unit 80 is attached to the opposite side surface. ing. The bottom decontamination unit 70 is for removing radioactive substances attached to the bottom 6. The lower dose measurement unit 80 is for measuring the dose of the bottom portion 6.

  The side decontamination unit 50 will be described in detail with reference to FIGS. 4 and 5. The side decontamination unit 50 includes a plurality of first side decontamination nozzles 51 as a projection type decontamination machine, a plurality of second side decontamination nozzles 52 as a projection type decontamination machine, and a plurality of suction ports. And a shatterproof hood 54. In FIG. 5, although the number of the first side decontamination nozzles 51 illustrated is one for convenience of the paper surface, a plurality of first side decontamination nozzles 51 are actually provided. Further, in FIG. 5, the scattering hood 54 is shown in a broken state in order to make the inside of the scattering prevention hood 54 easy to see.

  The shatterproof hood 54 is formed in a box shape in which the surface facing the inner surface of the side wall 7 is open. The opposite surface of the opening is attached to the bracket 38, and the bracket 38 is attached to the lifting platform 35. At the edge of the opening of the splash prevention hood 54, a seal member 54a composed of a rubber sheet and a dustproof brush is provided. The seal member 54 a is in sliding contact with the inner surface of the side wall 7, and the opening of the splash prevention hood 54 is closed by the inner surface of the side wall 7. Here, the rubber sheet and the dustproof brush of the seal member 54a are provided in a frame shape, and the dustproof brush is disposed inside the rubber sheet.

  Inside the shatterproof hood 54, a first side decontamination nozzle 51, a second side decontamination nozzle 52 and a suction port 53 are attached. The first side decontamination nozzle 51, the second side decontamination nozzle 52, and the suction port 53 are provided to project toward the inner surface of the side wall 7 from the surface opposite to the opening of the shatterproof hood 54. There is.

  The first side decontamination nozzle 51 is provided at one end of the supply pipe 51a. The second side decontamination nozzle 52 is provided at one end of the compressed air supply pipe 52a and the projection material supply pipe 52c. Here, one compressed air supply pipe 52 a and one projection material supply pipe 52 c are connected to one second side decontamination nozzle 52. The supply pipe 51a, the compressed air supply pipe 52a, and the projection material supply pipe 52c are piped from the scattering prevention hood 54 through the upper opening of the tank 5 to the working structure 10, and the supply pipe 51a, the compressed air supply pipe 52a and The other end of the projection material supply pipe 52c is connected to each of the connection ports 51b, 52b and 52d (see FIG. 2). The supply pipe 51a, the compressed air supply pipe 52a, and the projection material supply pipe 52c have flexibility in part or in their entirety.

  The suction port 53 is provided at one end of the suction pipe 53a. The other end of the suction pipe 53a is connected to the suction port of an air ejector 53g (see FIGS. 2 and 3) as an air transfer device. The compressed air intake port of the air ejector 53g is connected to one end of the supply pipe 53b, and the supply pipe 53b is piped from the air ejector 53g through the upper opening of the tank 5 to the working gantry 10, and the other end of the supply pipe 53b Are connected to the connection port 53c. The discharge port of the air ejector 53g is connected to one end of the discharge pipe 53d, and the discharge pipe 53d is piped from the air ejector 53g through the upper opening of the tank 5 to the working gantry 10, and the other end of the discharge pipe 53d is connected to the connection port 53e It is connected. The air ejector 53g is provided to the tank 5 in a state of being supported by the tubes 53a, 53b, 53d (see FIG. 3). These tubes 53a, 53b, 53d have flexibility in part or in their entirety.

Non-sublimation type projection material is pressure-fed to the first side decontamination nozzle 51 from the first projection material supply device 12 through the supply pipe 51a (see FIG. 10), and the first side decontamination nozzle 51 is non-sublimation type projection material Is sprayed toward the inner surface of the side wall 7.
Compressed air is fed from the blast compressor 14 through the compressed air supply pipe 52a to the second side decontamination nozzle 52, and a sublimation type projection material is supplied from the second projection material supply device 13 through the projection material supply pipe 52c. (See Figure 12). The second side decontamination nozzle 52 generates a negative pressure in the vicinity of the discharge port of the second side decontamination nozzle 52 by the compressed air sent from the compressed air supply pipe 52 a, and the sublimation type from the projection material supply pipe 52 c The projection material is sucked, and the sublimation projection material is sprayed toward the inner surface of the side wall 7.

The first side decontamination nozzle 51 is fixed so that the spray direction of the non-sublimation type projection material by the first side decontamination nozzle 51 is parallel to the radial direction of the side wall portion 7. The same applies to the second side decontamination nozzle 52.
However, the first side decontamination nozzle 51 and the second side decontamination nozzle 52 are swung by the swing device, and the projection material is sprayed by the first side decontamination nozzle 51 and the second side decontamination nozzle 52. The direction may change.

  When the non-sublimation projection material or the sublimation projection material collides with the inner surface of the side wall portion 7, the surface layer portion of the inner surface of the side wall portion 7 is scraped off. As a result, the radioactive substance adhering to the inner surface of the side wall 7 and the radioactive substance penetrating the surface layer of the side wall 7 are removed from the side wall 7. Moreover, the sprayed sublimation type projection material becomes gas by sublimation.

  Scattering of chips and non-sublimation type projection material scraped off from the side wall portion 7 is suppressed by the scattering prevention hood 54 and the seal member 54a. Cutting chips and non-sublimation type projectiles present in the shatterproof hood 54 are sucked into the suction port 53 and sent to the connection port 53e by the air ejector 53g (see FIG. 2). Here, when high pressure air is supplied to the air ejector 53g through the supply pipe 53b, the air ejector 53g uses the high pressure air to suck air from within the shatterproof hood 54 through the suction pipe 53a, and the sucked air and high pressure The air is mixed and discharged to the discharge pipe 53d.

  The side dose measurement unit 60 will be described in detail with reference to FIG. The side dose measuring unit 60 has a protective case 61, a side measuring instrument 62 and the like. The protective case 61 is attached to the bracket 39 and has a box shape. The side measuring instrument 62 is guided by the guide mechanism to be able to enter and exit the protective case 61. The guide mechanism is provided with a driving unit such as a motor, and the side measuring instrument 62 is accommodated in the protective case 61 or pulled out of the protective case 61 by the driving unit. The drive unit can be remotely controlled by the control panel in the control and monitoring room 11. In FIG. 4, the side measuring instrument 62 is shown pulled out of the protective case 61, in which state the side measuring instrument 62 faces the inner surface of the side wall 7. In this state, the side measuring instrument 62 measures the dose of the inner surface of the side wall 7 and outputs the measurement result to the control panel in the control and monitoring room 11 shown in FIG.

  The bottom decontamination unit 70 will be described in detail with reference to FIGS. 6 and 7. The bottom decontamination unit 70 includes a plurality of first bottom decontamination nozzles 71 as a projection decontamination machine, a plurality of second bottom decontamination nozzles 72 as a projection decontamination machine, a plurality of suction ports 73, and And a shatterproof hood 74. In FIG. 7, although the number of the second bottom decontamination nozzles 72 illustrated is one for convenience of the paper surface, a plurality of second bottom decontamination nozzles 72 are actually provided. Further, in FIG. 7, the scattering hood 74 is shown in a broken state in order to make the inside of the scattering prevention hood 74 easy to see.

  The shatterproof hood 74 is shaped like a box whose lower surface is open. The side of the shatterproof hood 74 is connected to the side of the bracket 49. At the edge of the opening of the shatterproof hood 74, a seal member 74a consisting of a rubber sheet and a dustproof brush is provided. The seal member 74 a is in sliding contact with the bottom 6, and the opening of the anti-scattering hood 74 is closed by the bottom 6.

  Inside the scattering prevention hood 74, a first bottom decontamination nozzle 71, a second bottom decontamination nozzle 72, and a suction port 73 are attached. The first bottom decontamination nozzle 71, the second bottom decontamination nozzle 72, and the suction port 73 are provided to project downward from the upper surface of the shatterproof hood 74.

  The first bottom decontamination nozzle 71 is provided at one end of the supply pipe 71a. The second bottom decontamination nozzle 72 is provided at one end of the compressed air supply pipe 72a and the projection material supply pipe 72c. Here, one compressed air supply pipe 72 a and one projection material supply pipe 72 c are connected to one second bottom decontamination nozzle 72. The supply pipe 71a, the compressed air supply pipe 72a and the projection material supply pipe 72c are piped from the scattering prevention hood 74 through the upper opening of the tank 5 to the working structure 10, and the supply pipe 71a, the compressed air supply pipe 72a and The other end of the projection material supply pipe 72c is connected to each of the connection ports 71b, 72b and 72d (see FIG. 2).

  The suction port 73 is provided at one end of the suction pipe 73a. The other end of the suction pipe 73a is connected to the suction port of the air ejector 73g (see FIGS. 2 and 3). In addition, the compressed air intake port of the air ejector 73g is connected to one end of the supply pipe 73b, and the supply pipe 73b is piped from the air ejector 73g through the upper opening of the tank 5 to the working gantry 10, and the other end of the supply pipe 73b Are connected to the connection port 73c. The discharge port of the air ejector 73g is connected to one end of the discharge pipe 73d, and the discharge pipe 73d is piped from the air ejector 73g through the upper opening of the tank 5 to the working gantry 10, and the other end of the discharge pipe 73d is connected to the connection port 73e It is connected. The air ejector 73g is provided in the tank 5 in a state of being supported by the tubes 73a, 73b, 73d (see FIG. 3).

A non-sublimation type projection material is pressure-fed to the first bottom decontamination nozzle 71 from the first projection material supply device 12 through the supply pipe 71a (FIG. 11), and the first bottom decontamination nozzle 71 is a non-sublimation type projection material. Spray towards.
Compressed air is fed from the blast compressor 14 through the compressed air supply pipe 72a to the second bottom decontamination nozzle 72, and a sublimation type projection material is supplied through the projection material supply pipe 72c (FIG. 13). The second bottom decontamination nozzle 72 generates a negative pressure in the vicinity of the discharge port of the second bottom decontamination nozzle 72 by the compressed air sent from the compressed air supply pipe 72a, and the sublimation type projection material from the projection material supply pipe 72c. And spray the sublimation projectile toward the inner surface of the side wall 7.

The first bottom decontamination nozzle 71 is fixed so that the spraying direction of the non-sublimation projection material by the first bottom decontamination nozzle 71 intersects the bottom 6. The same applies to the second bottom decontamination nozzle 72.
However, the first bottom decontamination nozzle 71 and the second bottom decontamination nozzle 72 are swung by the swing device, and the spray direction of the projection material by the first bottom decontamination nozzle 71 and the second bottom decontamination nozzle 72 changes. It is good also as things.

  When the non-sublimation projection material or the sublimation projection material collides with the bottom portion 6, the surface portion of the bottom portion 6 is scraped off. As a result, the radioactive substance attached to the bottom portion 6 and the radioactive substance which has permeated to the surface portion of the bottom portion 6 are removed from the bottom portion 6. Moreover, the sprayed sublimation type projection material becomes gas by sublimation.

  Scattering of chips and non-sublimation type projection material scraped off from the bottom portion 6 is suppressed by the scattering prevention hood 74 and the seal member 74a. The cuttings and non-sublimation type projection materials present in the shatterproof hood 74 are sucked into the suction port 73 and sent to the connection port 73 e by the air ejector 73 g. Here, when high pressure air is supplied to the air ejector 73g through the supply pipe 73b, the air ejector 73g sucks in air from within the scattering prevention hood 74 through the suction pipe 73a using the high pressure air, and the sucked air and high pressure It mixes with air and discharges it to the discharge pipe 73d.

  The lower dose measurement unit 80 will be described in detail with reference to FIG. The lower dose measurement unit 80 has a protective case 81, a lower measurement instrument 82, and the like. The protective case 81 is attached to the bracket 49 and is box-shaped. The lower measuring instrument 82 is guided to the protective case 81 in an accessible manner by the guide mechanism. The guide mechanism guides the lower measuring instrument 82 from the inside to the outside of the protective case 81. The guide mechanism is provided with a drive unit such as a motor, and the lower measurement instrument 82 is accommodated in the protective case 81 or pulled out of the protective case 81 by the drive unit. In FIG. 7, the lower measuring device 82 is shown pulled out of the protective case 81, and the lower measuring device 82 faces the bottom 6 in that state. In this state, the lower measuring instrument 82 measures the dose of the bottom portion 6, and outputs the measurement result to the control panel in the control and monitoring room 11 shown in FIG.

  With reference to FIG. 8, the grinding-type upper decontamination machine 90 which decontaminates the upper end part of the inner surface of the side wall part 7 is demonstrated. The upper decontamination machine 90 is provided at the upper end of the vertical member 30. The upper decontamination machine 90 has a motor 91 and a wire brush 92. The motor 91 is attached to the upper end of the vertical member 30 by the bracket 93, and the shaft of the motor 91 extends upward. A wire brush 92 is directly connected to the shaft of the motor 91. Here, the wire brush 92 has a shaft portion directly connected to the shaft of the motor 91, and a large number of wires extending radially outward from the shaft portion.

  When the wire brush 92 is rotationally driven by the motor 91, the wire of the wire brush 92 collides with the inner surface of the side wall 7, and the inner surface of the side wall 7 is ground by the wire brush 92. As a result, the radioactive substance adhering to the inner surface of the side wall 7 and the radioactive substance penetrating the surface layer of the side wall 7 are removed from the side wall 7.

  The upper decontamination machine 90 is for decontaminating a range which can not be decontaminated by the side decontamination unit 50. That is, the upper decontamination machine 90 decontaminates the region above the movable range of the side decontamination unit 50 and the jettable range of the side decontamination nozzles 51 and 52.

  With reference to FIG. 9, the grinding-type lower decontamination machine 95 which decontaminates the lower end part of the inner surface of the side wall part 7 is demonstrated. The lower decontamination machine 95 is provided at the lower end of the vertical member 30. The lower decontamination machine 95 has a motor 96 and a wire brush 97. A motor 96 is attached to the lower end of the upright 30 by a bracket 98 and the shaft of the motor 96 extends downwardly. A wire brush 97 is directly connected to the shaft of the motor 96. Here, the wire brush 97 has a shaft connected directly to the shaft of the motor 96, and a large number of wires extending radially outward from the shaft.

  When the wire brush 97 is rotationally driven by the motor 96, the wire of the wire brush 97 collides with the inner surface of the side wall 7, and the inner surface of the side wall 7 is ground by the wire brush 97. As a result, the radioactive substance adhering to the inner surface of the side wall 7 and the radioactive substance penetrating the surface layer of the side wall 7 are removed from the side wall 7.

  The lower decontamination machine 95 is for decontaminating an area which can not be decontaminated by the side decontamination unit 50. That is, the lower decontamination machine 95 decontaminates the area below the movable range of the side decontamination unit 50 and the jettable range of the side decontamination nozzles 51 and 52.

  Subsequently, the installation state of the lid 9 will be described. As shown in FIGS. 3 and 4, a plurality of supports 8 are attached to the upper end of the side wall 4 so as to be arranged at equal intervals in the circumferential direction. As shown in FIG. 4, the lid 9 is placed on the supports 8, and the lid 9 is fixed to the supports 8 by bolts or the like. The lid 9 is separated from the upper rails 21, 22 and the tooth track 23 by being placed on the support 8. Since the lid 9 is separated upward from the upper rails 21 and 22 by the support stand 8, a moving space for the upper mounts 25 and 26 and the motors 27 and 28 is secured. The upper mounts 25, 26 pivot along the upper rails 21, 22 between the lid 9 and the upper rails 21, 22. In addition, in FIG. 4, the outer peripheral part of the lid | cover 9 is shown with a dashed-two dotted line.

  As shown in FIG. 1, a protective sheet 4 is provided on the periphery of the lid 9, and a gap 9 b (see FIG. 4) between the lid 9 and the upper rails 21 and 22 is closed by the protective sheet 4.

  The dust collection in the tank 5 will be described with reference to FIG. In the vicinity of the tank 5, a dust collection device 3 configured by a HEPA filter or the like is installed, and the connection pipe 3 a is piped from the dust collection device 3 to the lower end portion of the side wall portion 7 of the tank 5. The dust collection device 3 sucks the air in the tank 5 through the connection pipe 3 a and captures dust in the sucked air. The air collected by the dust collector 3 is discharged from the dust collector 3 to the atmosphere.

  Further, the lid 9 is provided with an outside air introduction hole 9a. As the air in the tank 5 is sucked by the dust collector 3, the air outside the tank 5 is introduced into the tank 5 through the outside air introduction hole 9 a. A fan may be provided in the outside air introduction hole 9a, and air outside the tank 5 may be introduced into the tank 5 by forced convection of the fan.

2. Method of Using Decontamination Equipment and Decontamination Method A method of decontaminating the tank 5 using the decontamination equipment 1 will be described.

(1) Piping First, as shown in FIG. 10, on the working gantry 10, the connecting pipe 12a is piped from the first projectile supply device 12 to the connecting port 51b, and the connecting pipe 14a is connected from the blast compressor 14 to the connecting pipe. The piping is performed up to 12a (in particular, in the vicinity of the first projectile supply device 12). Further, the connecting pipe 15a is piped from the suction compressor 15 to the connecting port 53c, and the connecting pipe 16a is piped from the connecting port 53e to the projection material recovery device 16. Further, the connecting pipe 17 a is piped from the projection material recovery device 16 to the air classification device 17 e of the cuttings recovery device 17. Thereby, the first side decontamination nozzle 51 and the suction port 53 of the side decontamination unit 50 are made available.

(2) Measurement of dose distribution in the side wall Next, the control unit in the control and monitoring room 11 remotely operates the drive unit of the side dose measurement unit 60 to pull out the side measurement instrument 62 from the protective case 61 (see FIG. 4). Then, by scanning the inner surface of the side wall 7 with the side measuring instrument 62 of the side dose measuring unit 60, the dose distribution of the inner surface of the side wall 7 is measured. At this time, the side portion 62 of the side portion 62 of the side dose measurement unit 60 is constructed by combining the turning operation of the upper mounts 25 and 26 by the turning motors 27 and 28 and the raising and lowering operation of the lifting mount 35 by the lifting motor 37. The dose of the inner surface of the side wall 7 is measured by the side measuring instrument 62 while moving along the inner surface of the Then, the measurement results are sequentially output from the side measuring instrument 62 to the control panel in the control monitoring room 11. As a result, the dose distribution on the inner surface of the side wall 7 is recorded on the control panel in the control and monitoring room 11.

  The scanning of the inner surface of the side wall 7 will be specifically described. First, the lifting frame 35 is raised by the lifting motor 37 to the upper end of the lifting rails 31 and 32. Next, while measuring the dose of the inner surface of the side wall 7 by the side measuring instrument 62, the upper mounts 25, 26 are turned 360 ° by the turning motors 27, 28. Next, the lifting and lowering base 35 is lowered by the lifting motor 37 by an amount corresponding to the vertical length of the area that can be measured by the side measuring instrument 62. Thereafter, the dose distribution of the entire inner surface of the side wall portion 7 is measured by alternately repeating the swinging of the upper mounts 25 and 26 and the lowering of the lifting mount 35. Here, with regard to the pivoting of the upper mounts 25 and 26, clockwise 360 ° pivoting and counterclockwise 360 ° pivoting are alternately repeated.

  When the upper mounts 25 and 26 are turned, the turning motors 27 and 28 are synchronously controlled to synchronize the turning start timings of the upper mounts 25 and 26 so that the swing speeds of the upper mounts 25 and 26 are equal to each other. The stop timings of 25 and 26 are synchronized. Therefore, the relative positional relationship between the upper mounts 25 and 26 does not change. Therefore, distortion and deformation of the vertical member 30, the elevating rails 31, 32, the tooth track 33, the lower rails 41, 42 and the tooth track 43 can be suppressed without providing a horizontal member between the upper mounts 25 and 26. , The configuration of these assemblies becomes simple.

  When the measurement of the dose distribution over the entire inner surface of the side wall portion 7 is completed, the drive unit of the side dose measuring unit 60 is remotely operated by the control panel in the control monitoring room 11 to store the side measuring instrument 62 in the protective case 61 Do. Further, the lifting and lowering base 35 is raised to the upper end portions of the lifting and lowering rails 31 and 32 by the lifting and lowering motor 37.

(3) Decontamination of the side wall Next, the side decontamination unit 50 is constructed by combining the turning operation of the upper mounts 25 and 26 by the turning motors 27 and 28 and the raising and lowering operation of the lifting mount 35 by the lifting motor 37. Move along the inner surface of the part 7.
Specifically, the upper mounts 25 and 26 are turned 360 ° by the turning motors 27 and 28. Next, the lifting and lowering stand 35 is lowered by the raising and lowering motor 37 by the length of the upper and lower portions of the area where the non-sublimation type projection material is projected by the first side decontamination nozzle 51. Thereafter, the turning of the upper mounts 25 and 26 and the lowering of the lifting mount 35 are alternately repeated. With regard to the pivoting of the upper mounts 25 26, clockwise 360 ° pivoting and counterclockwise 360 ° pivoting are alternately repeated.
The swing speed of the upper mounts 25 and 26 is controlled, for example, as in the following (A) or (B).
(A) The constant speed control of the turning motors 27, 28 is performed to turn the upper mounts 25, 26 at a constant speed.
(B) Normally, the upper gantry 25, 26 is pivoted at the same speed as described in (A) above, but when the side decontamination unit 50 passes through a high dose portion, the upper gantry 25, 26 is Slow down. Here, it can be determined from the dose distribution measured as described above whether the dose at any part of the inner surface of the sidewall 7 is high.

  As described above, while moving the side decontamination unit 50 along the inner surface of the side wall 7, the blast compressor 14, the first projectile supply device 12, the suction compressor 15, the dust collector 18, and the dust collection Activate the device 3 Then, the non-sublimation type projection material delivered from the first projectile supply device 12 is pressure-fed to the first side decontamination nozzle 51 by the air compressed by the blast compressor 14, and the first side decontamination is performed. It is projected from the nozzle 51 onto the inner surface of the side wall 7. Further, the air compressed by the suction compressor 15 is sent to the air ejector 53g, whereby the air in the shatterproof hood 54 is sucked into the suction port 53 and sent to the projection material recovery device 16. In addition, since the spraying time with respect to the site | part with high dose becomes long by decelerating the upper mount frame 25 and 26 like above-mentioned (B), the site | part can be wash | cleaned intensively.

  The non-sublimation type projection material is sprayed on the inner surface of the side wall 7, whereby the surface layer of the inner surface of the side wall 7 is scraped off. The cutting chips and non-sublimation type projectile are sent together with air from the suction port 53 to the projectile collection device 16 via the pipes 53a, 53d and 16a, and the non-sublimation type projectile contained in the air is projectile The non-sublimation type projectile is separated by the recovery unit 16, and the non-sublimation type projectile is sent from the projectile recovery unit 16 to the first projectile supply unit 12. In this way, the non-sublimation type projectile can be circulated and reused.

  The air from which the non-sublimation type projectiles are separated is sent from the projectiles collection device 16 to the cuttings collection device 17. The chips contained in the air are collected by the chip collection device 17. The air from which the cuttings are separated is sent from the cuttings collection device 17 to the dust collector 18. The air is filtered by the dust collector 18 and discharged from the dust collector 18 to the atmosphere.

  The cutting chips and non-sublimation type projection material leaked from the scattering prevention hood 54 fall. The cutting chips and the non-sublimation type projection material are sent to the dust collector 3 together with air and captured by the dust collector 3. Air from which cutting chips and non-sublimation projectiles are separated is discharged to the atmosphere.

  While the upper mounts 25 and 26 make at least one turn, the motors 91 and 96 of the decontamination unit 90 and 95 (see FIGS. 8 and 9) are operated. Then, the upper end portion of the inner surface of the side wall portion 7 is ground by the wire brush 92, and the lower end portion of the inner surface of the side wall portion 7 is ground by the wire brush 97.

  As described above, since the decontamination of the side wall portion 7 is sequentially performed from the top to the bottom by the first side projection nozzle 51 of the side decontamination unit 50, the site that has already been decontaminated leaks from the shatterproof hood 54 It is possible to suppress radioactive contamination again by cutting chips and non-sublimation projectiles.

(4) Dose distribution measurement and re-decontamination of the side wall portion After decontamination of the entire side wall portion 7 is completed, the dose distribution of the inner surface of the side wall portion 7 is carried out in the same manner as the dose distribution measuring step of the inner surface of the side wall portion 7 described above. Measure Thereby, the decontamination effect can be confirmed.
When there is a part that can not be sufficiently decontaminated, a part that is insufficiently decontaminated due to the combination of the pivoting motion of the upper mounts 25 and 26 by the pivoting motors 27 and 28 and the lifting and lowering motion of the lifting and lowering mount 35 by the lifting and lowering motor 37 The side decontamination unit 50 is moved to spray the non-sublimation type projection material onto the decontaminated part by the first side decontamination nozzle 51. Thereafter, the decontamination effect is confirmed by measuring the dose of the site by the side dose measurement unit 60.

(5) Refilling of piping If the dose becomes lower than a predetermined value at any part of the inner surface of the side wall 7, the replacement of piping is performed. Specifically, the connecting pipes 12a, 14a, 15a, 16a (see FIG. 10) are removed. Then, as shown in FIG. 11, the connecting pipe 12b is piped from the first projectile supply device 12 to the connecting port 71b, and the connecting pipe 14b is connected from the blast compressor 14 to the connecting pipe 12b (in particular, the first projectile supplying device Pipe up to around 12). Further, the connecting pipe 15b is piped from the suction compressor 15 to the connecting port 73c, and the connecting pipe 16b is piped from the connecting port 73e to the projection material recovery device 16. Thereby, the first bottom decontamination nozzle 71 and the suction port 73 of the bottom decontamination unit 70 are made usable.

(6) Measurement of dose distribution at the bottom Next, the control unit in the control and monitoring room 11 remotely operates the drive unit of the lower dose measurement unit 80 to pull out the lower measuring instrument 82 from the protective case 81 (FIG. 6, FIG. 7). Then, by scanning the bottom 6 with the lower measuring instrument 82 of the lower dose measuring unit 80, the dose distribution of the bottom 6 is measured. At this time, the lower measuring instrument 82 of the lower dose measuring unit 80 is arranged along the bottom portion 6 by a combination of the swinging motion of the upper mounts 25 and 26 by the swinging motors 27 and 28 and the traversing motion of the lower mount 45 by the traversing motor 47. While being moved, the dose of the bottom portion 6 is measured by the lower measuring instrument 82, and the measurement result is sequentially output from the lower measuring instrument 82 to the control panel in the control and monitoring room 11. Thereby, the dose distribution of the bottom portion 6 is recorded on the control panel in the control and monitoring room 11.

  The scanning of the bottom portion 6 will be specifically described. First, the lower mount 45 is moved to one end of the lower rails 41 and 42 by the traverse motor 47. Next, while the dose of the bottom portion 6 is measured by the lower measuring instrument 82, the upper mounts 25, 26 are turned 180 ° by the turning motors 27, 28. Next, the lower mount 45 is moved in the radial direction by the traverse motor 47 by the radial length of the area that can be measured by the lower measuring instrument 82. While the lower gantry 45 moves from one end to the other end of the lower rails 41, 42, the turning of the upper gantry 25, 26 and the traversing of the lower gantry 45 are alternately repeated. Thereby, the dose distribution of the whole bottom part 6 is measured. Here, with regard to the pivoting of the upper mounts 25 and 26, clockwise 180 ° pivoting and counterclockwise 180 ° pivoting are alternately repeated. Therefore, after half scan of half of bottom 6 is made from the outer periphery toward the center, half scan is made from the center of the other half toward the outer periphery.

  When the measurement of the dose distribution of the entire bottom portion 6 is completed, the drive unit of the lower dose measurement unit 80 is remotely controlled by the control panel in the control and monitoring room 11, and the lower measurement instrument 82 is housed in the protective case 81.

(7) Decontamination of the bottom Next, the bottom decontamination unit 70 is turned to the bottom 6 by a combination of the swing operation of the upper mounts 25 and 26 by the swing motors 27 and 28 and the traversing operation of the lower mount 45 by the traversing motor 47. Move along.
Specifically, the upper mounts 25 and 26 are turned 180 ° by the turning motors 27 and 28. Next, the lower gantry 45 is traversed by the traverse motor 47 by the length of the radial direction of the area where the non-sublimation projection material is projected by the first bottom decontamination nozzle 71. While the lower gantry 45 moves from one end to the other end of the lower rails 41, 42, the turning of the upper gantry 25, 26 and the traversing of the lower gantry 45 are alternately repeated. Here, with regard to the pivoting of the upper mounts 25 and 26, clockwise 180 ° pivoting and counterclockwise 180 ° pivoting are alternately repeated.
The swing speed of the upper mounts 25 and 26 is controlled, for example, as described above in (A) or (B).

  As described above, while moving the bottom part decontamination unit 70 along the bottom part 6, the blast compressor 14, the first projectile supply device 12, the suction compressor 15, the dust collector 18, and the dust collector 3 are operated. Let Then, the non-sublimation type projection material is projected from the first bottom decontamination nozzle 71 to the bottom portion 6, and the surface portion of the bottom portion 6 is scraped off by the non-sublimation type projection material. In addition, the air in the scattering prevention hood 74 is sent to the projection material recovery device 16 together with the non-sublimation type projection material and cutting debris. The non-sublimation type projectile contained in the air is separated by the projectile collection device 16, and the non-sublimation type projectile is sent from the projectile collection device 16 to the first projectile supply device 12. The air from which the non-sublimation type projectiles are separated is sent from the projectiles collection device 16 to the cuttings collection device 17. The chips contained in the air are collected by the chip collection device 17. The air from which the chips are separated is filtered by the dust collector 18 and then discharged from the dust collector 18 to the atmosphere.

  The cuttings and non-sublimation projection materials leaked from the scattering prevention hood 74 are sent to the dust collector 3 together with the air and captured by the dust collector 3. The air from which cutting chips and non-sublimation projectiles are separated is discharged from the dust collector 3.

(8) Measurement of Dose Distribution at the Bottom and Recontamination When the entire decontamination of the bottom 6 is completed, the dose distribution at the bottom 6 is measured in the same manner as the step of measuring the dose distribution of the bottom 6 described above. Thereby, the decontamination effect can be confirmed.
If there is a part that can not be sufficiently decontaminated, a part of insufficient decontamination due to the combination of the turning movement of the upper mounts 25 and 26 by the turning motors 27 and 28 and the traversing action of the lower mount 45 by the traversing motor 47 The bottom decontamination unit 70 is moved to spray the non-sublimation type projection material onto the decontaminated part by the first bottom decontamination nozzle 71. Thereafter, the dose of the site is measured by the lower dose measurement unit 80 to confirm the decontamination effect.

(9) Refilling of piping Refilling of piping is performed when the dose becomes lower than a predetermined value at any part of the bottom part 6. Specifically, the connecting pipes 12b, 14b, 15b, 16b and 17a (see FIG. 11) are removed. Then, as shown in FIG. 12, the connecting pipe 13c is piped from the second projectile supply device 13 to the connecting port 52d, and the connecting pipe 14c is piped from the blast compressor 14 to the connecting port 52b. Further, the connecting pipe 15c is piped from the suction compressor 15 to the connecting port 53c, and the connecting pipe 17c is piped from the connecting port 53e to the air classification device 17e of the scrap collection device 17. This enables the second side decontamination nozzle 52 and the suction port 53 of the side decontamination unit 50 to be usable.

(10) Decontamination of the side wall Next, as described in “(3) Decontamination of the side wall”, the turning operation of the upper mounts 25 and 26 by the turning motors 27 and 28 and the raising and lowering motor 37 The side decontamination unit 50 is moved along the inner surface of the side wall 7 in combination with the lifting and lowering operation of the lifting and lowering stand 35. At this time, the blast compressor 14, the second projectile supply device 13, the suction compressor 15, the dust collector 18, and the dust collector 3 are operated. Then, the sublimation projection material is projected from the second side decontamination nozzle 52 onto the inner surface of the side wall 7, and the surface layer portion of the inner surface of the sidewall 7 is scraped off by the sublimation projection material, and the sublimation projection material projected Will sublime. In addition, non-sublimation type projectiles and cuttings attached to the side wall portion 7 in the previous decontamination process are also exfoliated by the collision of the sublimation type projectiles.

  Further, the air in the shatterproof hood 54 is sucked by the suction port 53 and is sent to the scrap collection device 17. The chips contained in the air are collected by the chip collection device 17. The air from which the chips are separated is filtered by the dust collector 18 and then discharged from the dust collector 18 to the atmosphere.

(11) Measurement of Dose Distribution in Side Wall After completion of decontamination of the entire side wall 7, the dose distribution in the inner side of the side wall 7 is measured in the same manner as the step of measuring the dose distribution on the inner surface of the side wall 7 described above. Thereby, the decontamination effect can be confirmed.

(12) Refilling of piping Next, the connecting pipes 13c, 14c, 15c and 17c (see FIG. 12) are removed. Then, as shown in FIG. 13, the connecting pipe 13d is piped from the second projectile supply device 13 to the connecting port 72d, and the connecting pipe 14d is piped from the blast compressor 14 to the connecting port 72b. Further, the connecting pipe 15d is piped from the suction compressor 15 to the connecting port 73c, and the connecting pipe 17d is piped from the connecting port 73e to the air classification device 17e of the scrap collection device 17. Thereby, the second bottom decontamination nozzle 72 and the suction port 73 of the bottom decontamination unit 70 are made usable.

(13) Decontamination of the bottom Next, as described in the section "(7) Decontamination of the bottom", the swing operation of the upper mounts 25 and 26 by the swing motors 27 and 28 and the lower mount by the traversing motor 47 The bottom decontamination unit 70 is moved along the bottom 6 in combination with 45 traversing movements. At this time, the blast compressor 14, the second projectile supply device 13, the suction compressor 15, the dust collector 18, and the dust collector 3 are operated. Then, the sublimation projection material is projected from the second bottom decontamination nozzle 72 to the bottom portion 6, the surface layer portion of the bottom portion 6 is scraped off by the sublimation projection material, and the projected sublimation projection material is sublimated. In addition, non-sublimation type projectiles and cuttings attached to the bottom portion 6 in the previous decontamination step are also exfoliated by the collision of the sublimation type projectiles.

  Further, the air in the shatterproof hood 74 is sucked by the suction port 73 and is sent to the scrap collection device 17. The chips contained in the air are collected by the chip collection device 17. The air from which the chips are separated is filtered by the dust collector 18 and then discharged from the dust collector 18 to the atmosphere.

(14) Measurement of Dose Distribution at Bottom When the decontamination of the entire bottom 6 is completed, the dose distribution at the bottom 6 is measured in the same manner as the step of measuring the dose distribution of the bottom 6 described above. Thereby, the decontamination effect can be confirmed.

4. Effects (1) The upper mounts 25 and 26, the lifting mount 35 and the lower mount 45 are self-propelled, and the decontamination units 50 and 70 are provided on the lift mount 35 and the lower mount 45, respectively. Therefore, the bottom 6 and the side wall 7 of the tank 5 can be decontaminated even if no worker enters the tank 5.

(2) Since the dose measurement units 60 and 80 are respectively provided on the lifting platform 35 and the lower platform 45, the dose distribution of the bottom portion 6 and the side wall portion 7 of the tank 5 is measured even if no worker enters the tank 5 can do.

(3) Even if the upper end of the inner surface of the side wall 7 can not be decontaminated by the decontamination unit 50, the upper decontamination machine 90 can decontaminate the upper end of the inner surface of the side wall 7. Even if the lower end of the inner surface of the side wall 7 can not be decontaminated by the decontamination unit 50, the lower decontamination machine 95 can decontaminate the lower end of the inner surface of the side wall 7.

(4) The scattering prevention hoods 54 and 74 suppress scattering of cuttings and projectiles, so that radioactive substances can be prevented from being deposited on the bottom portion 6 of the tank 5. Even if cuttings and projection materials leak from the splash prevention hoods 54 and 74, the cuttings and projection materials are captured by the dust collection device 3.

(5) The non-sublimation type projection material blown out from the first side projection nozzle 51 and the first lower projection nozzle 71 is recovered by the projection material recovery device 16 and the non-sublimation type projection material is circulated, Generation of radioactively contaminated non-sublimation type projectile can be minimized. In addition, radioactively contaminated non-sublimation projectiles are not released to the atmosphere.

(6) Since the non-sublimation type projection material does not sublime, the non-sublimation type projection material can be strongly sprayed to the bottom portion 6 and the side wall portion 7. Therefore, if the non-sublimation type projection material is used, the bottom portion 6 and the side wall portion 7 can be efficiently decontaminated. However, since there is a possibility that the non-sublimation projection material may be attached to the bottom 6 or the side wall 7, the non-sublimation projection material attached to the bottom 6 or the side wall 7 can be peeled off by spraying the sublimation projection material. Moreover, since the sublimation type projection material is sublimated, it is possible to suppress the sublimation type projection material from remaining on the bottom portion 6 and the side wall portion 7.

(7) Since the dust-containing air is filtered by the dust collectors 3 and 18, the release of radioactive substances to the atmosphere can be prevented.

5. Although the embodiments for carrying out the present invention have been described above, the above embodiments are for the purpose of facilitating the understanding of the present invention, and are not for the purpose of limiting the present invention and interpreting it.
Further, the present invention can be changed and improved without departing from the gist thereof, and the present invention also includes the equivalents thereof. The changes from the above embodiment will be described below. The various modifications described below may be combined and applied.

(1) In the above-mentioned embodiment, at the time of decontamination of the bottom part 6, the bottom part decontamination unit 70 was drawing the semicircular locus repeatedly. On the other hand, the bottom decontamination unit 70 may draw a linear trajectory. Specifically, at the same time the upper mounts 25 and 26 are turned by the turning motors 27 and 28, the lower mount 45 is made to traverse by the traverse motor 47, and the moving speeds of the upper mounts 25 and 26 and the lower mount 45 are further Adjust the Then, the bottom decontamination unit 70 draws a linear locus along the chord or diameter of the outer circumferential circle of the bottom 6.

By the way, as shown in FIG. 3, the bottom 6 is provided with grid-like ribs 6a. The rectilinear movement of the bottom decontamination unit 70 along the rib 6 a enables the decontamination of the rib 6 a in a focused manner.
In addition, also when measuring the dose distribution of the bottom part 6, the dose of the rib 6a can be measured by carrying out the linear motion of the lower dose measurement unit 80 along the rib 6a similarly.

(2) In the above embodiment, both the non-sublimation type projection material and the sublimation type projection material are sprayed on the inner surface of the side wall 7 by shifting the projection timing of the non-sublimation type projection material and the projection timing of the sublimation type projection material. The On the other hand, either the non-sublimation projection material or the sublimation projection material may be sprayed on the inner surface of the side wall portion 7. Alternatively, both the non-sublimation projection material and the sublimation projection material may be sprayed simultaneously on the inner surface of the side wall 7 (in this case, two blast compressors 14 are installed).
The same applies to the decontamination of the bottom 6.

(3) In the embodiment described above, the upper decontamination machine 90 is attached to the upper end of the vertical member 30. On the other hand, an upper decontamination machine similar to the upper decontamination machine 90 may be attached to the upper end of the elevating rails 31, 32. In this case, the upper decontamination machine 90 may be attached to the upper end of the vertical member 30, or the upper decontamination machine 90 may not be provided.

(4) In the embodiment described above, the lower decontamination machine 95 is attached to the lower end of the vertical member 30. On the other hand, a lower decontamination apparatus similar to the lower decontamination apparatus 95 may be attached to the lower end of the elevating rails 31, 32. In this case, the lower decontamination machine 95 may be attached to the lower end of the vertical member 30, or the lower decontamination machine 95 may not be provided.

(5) A grinding type decontamination machine similar to the decontamination machines 90 and 95 may be attached to the inside of the splash prevention hood 54, and the inner surface of the side wall 7 may be ground by the grinding type decontamination machine. Even when the inner surface of the side wall portion 7 is ground by the grinding type decontamination machine, the combination of the turning operation of the upper mounts 25 and 26 by the turning motors 27 and 28 and the lifting and lowering motion of the lifting and lowering mount 35 by the lifting and lowering motor 37 And the shatterproof hood 54 is moved along the inner surface of the side wall 7.
Similarly, a grinding type decontamination machine (however, the axis of the wire brush is horizontal) may be attached to the inside of the shatterproof hood 74, and the bottom 6 may be ground by the grinding type decontamination machine.

(6) The vertical member 30 may be used as a rail, and a lifting platform similar to the lifting platform 35 (hereinafter referred to as the second lifting platform in the section (6)) may be mounted so as to be able to move up and down along the vertical member 30 . In this case, the tooth track is vertically suspended from the second upper gantry 26 along the inner surface of the side wall 7 of the tank 5, the tooth track is provided parallel to the vertical member 30, and the motor is provided on the second lifting platform Engage the gear of the motor shaft with its gear. Further, a decontamination unit similar to the decontamination unit 50 is attached to the second lifting and lowering stand, and a dose measuring unit similar to the dose measuring unit 60 is attached to the second lifting and lowering stand. The second lifting and lowering frame is moved up and down in the same manner as the lifting and lowering frame 35, and the decontamination unit and the dose measuring unit provided on the second lifting and lowering frame are also operated in the same manner as the decontamination unit 50 and the dose measuring unit 60. Then, even if the swing angle of the upper mounts 25 and 26 is 180 °, it is possible to decontaminate substantially the entire side wall portion 7.

(7) In the embodiment described above, the decontamination nozzles 51, 52, 71, 72, the suction ports 53, 73, the air ejectors 53g, 73g, the first projectile supply device 12, the second projectile by restocking the piping The path between the supply device 13, the blast compressor 14, the suction compressor 15, the projection material recovery device 16, the cutting debris recovery device 17 and the dust collector 18 has been changed. On the other hand, decontamination nozzles 51, 52, 71, 72, suction ports 53, 73, air ejectors 53g, 73g, first using a plurality of valves (for example, direction control valve, switching valve, on-off valve, etc.) The path between the projection material supply device 12, the second projection material supply device 13, the blast compressor 14, the suction compressor 15, the projection material collection device 16, the cuttings collection device 17, and the dust collection device 18 may be changed.

(8) In the above embodiment, the tank 5 is cylindrical. On the other hand, as shown in FIG. 14, the decontamination machine 102 may be attached to the rectangular tank 105. The rectangular tank 105 and the decontamination machine 102 will be described in detail.

  As shown in FIG. 14, the tank 105 is of an open top type, and four upper rails 121 to 124 are assembled in a rectangular frame shape, and these upper rails 121 to 124 are at the upper ends of the side walls 105 a to 105 d of the tank 105. Each is provided. Furthermore, tooth tracks 125 to 128 are provided in parallel with the upper rails 121 to 124 at the upper ends of the side wall portions 105 a to 105 d of the tank 105, respectively. Upper mounts 131 to 134 are attached to the upper rails 121 to 124 so that they can travel. The upper mounts 131 to 134 are respectively provided with motors, and the gears provided on the shafts of these motors mesh with the tooth tracks 125 to 128, respectively, and the upper mounts 131 to 134 travel along the upper rails 121 to 124 by the motors. .

  In addition, elevating rails (vertical members) 141 to 144 vertically hang from the upper mounts 131 to 134 along the inner surfaces of the side walls 105a to 105d, respectively. Similarly, tooth tracks 145 to 148 hang from upper mounts 131 to 134 along the inner surfaces of side walls 105 a to 105 d, respectively. Lifting racks 151 to 154 are attached to these lifting rails 141 to 144 so as to be able to move up and down. Motors are provided on the elevating mounts 151 to 154, respectively. Gears provided on the shafts of these motors mesh with the tooth tracks 145 to 148, and the elevating mounts 151 to 154 are moved up and down along the elevating rails 141 to 144 by the motors. .

  A lower rail 161 and a lower gear 162 are horizontally installed between the lower end of the lift rail 142 and the lower gear 146 and the lower end of the lower rail 144 and the lower gear 148. A lower mount frame 171 is attached to the lower rail 161 so as to be movable. The lower pedestal 171 is provided with a motor, and a gear provided on the shaft of the motor meshes with the tooth track 162, and the lower pedestal 171 travels along the lower rail 161 by the motor.

  A beam 163 is horizontally installed between the lower end portions of the elevation rails 141 and the tooth tracks 145 and the lower ends of the elevation rails 143 and the tooth tracks 147.

Decontamination units similar to the side decontamination units 50 (see FIGS. 4 and 5) are attached to the elevating mounts 151 to 154, respectively. Furthermore, dose measurement units similar to the side dose measurement unit 60 (see FIG. 4) are attached to the elevating mounts 151 to 154, respectively.
A lower decontamination unit similar to the bottom decontamination unit 70 (see FIGS. 6 and 7) is attached to the lower pedestal 171. Furthermore, a dose measurement unit similar to the lower dose measurement unit 80 (see FIGS. 6 and 7) is attached to the lower gantry 171.

  At the time of decontamination of the side wall portions 105a and 105c of the tank 105, the decontamination unit is formed of the side wall portion 105a, by combining the traversing operation of the upper mounts 131 and 133 by the motor and the lifting and lowering operation of the lifting mounts 151 and 153 by the motor. Move along the inner surface of 105c. At this time, the upper mounts 131 and 133 run in parallel. Further, at this time, the projection material is sprayed toward the side wall portions 105a and 105c from the decontamination nozzle of the decontamination unit.

  At the time of decontamination of the side wall portions 105b and 105d, the decontamination unit is formed on the inner surface of the side wall portions 105b and 105d by a combination of the traversing operation of the upper mounts 132 and 134 by the motor and the lifting and lowering operation of the lift Move along At this time, the upper mounts 132 and 134 run in parallel. Further, at this time, the projection material is sprayed toward the side wall portions 105 b and 105 d from the decontamination nozzle of the decontamination unit.

  At the time of decontamination of the bottom portion 105e of the tank 105, the decontamination unit is moved along the bottom portion 105e by a combination of the traversing operation of the upper mount 132, 134 by the motor and the traversing operation of the lower mount 171 by the motor. At this time, the upper mounts 132 and 134 run in parallel. Furthermore, at this time, the projection material is sprayed toward the bottom portion 105 e from the decontamination nozzle of the decontamination unit.

  DESCRIPTION OF SYMBOLS 1 ... Decontamination apparatus, 2 ... Decontamination machine, 3 ... Dust collection apparatus, 3a ... Connecting pipe, 4 ... Protective sheet, 5 ... Tank, 6 ... Bottom part, 6a ... Rib, 7 ... Side wall part, 8 ... Support stand, DESCRIPTION OF SYMBOLS 9 ... Lid, 9a ... Outside air introduction hole, 9b ... Clearance, 10 ... Work gantry, 11 ... Control surveillance room, 12 ... 1st projection material supply apparatus, 13 ... 2nd projection material supply apparatus, 14 ... Compressor for blasting, 15 ... compressor for suction, 16 ... projection material recovery device, 17 ... cutting waste recovery device, 17 e ... air classification device, 17 f ... cutting waste storage part 18 ... dust collection device, 21 ... upper rail, 22 ... upper rail, 23 ... tooth Rail, 25: first upper mount, 26: second upper mount, 27: motor, 28: motor 30: vertical member, 31: lift rail, 32: lift rail, 33: tooth track, 35: lift mount, 37 Motor, 38: Bracket, 39: Bracket, 41: lower rail, 43: tooth track, 45: lower mount, 47: motor, 49: bracket, 50: side decontamination unit, 51: first side decontamination nozzle (Side decontamination machine), 51a ... supply pipe, 51b ... connection port, 52 ... second side decontamination nozzle (side decontamination machine), 52a ... supply pipe, 52c ... projection material supply pipe, 53 ... suction Port, 53a: Suction pipe, 53b: Supply pipe, 53c: Connection port, 53d: Discharge pipe, 53e: Connection port, 53g: Air ejector, 54: Scatter prevention hood, 54a: Seal member, 60: Side dose measurement unit, DESCRIPTION OF SYMBOLS 61 ... Protective case, 62 ... Side measuring instrument, 70 ... Bottom decontamination unit, 71 ... 1st bottom decontamination nozzle (bottom decontamination machine), 71a ... Supply pipe, 71 b ... connection port, 72 ... second bottom decontamination nozzle (bottom decontamination machine), 72a ... supply pipe, 72c ... projection material supply pipe, 73 ... suction port, 73a ... suction pipe, 73b ... supply pipe, 73c ... connection Port 73d Discharge pipe 73e Connecting port 73g Air ejector 74 Scattering prevention hood 74a Sealing member 80 Lower dose measuring unit 81 Protective case 82 Lower measuring instrument 90 Upper decontamination , 91 ... motor, 92 ... wire brush, 93 ... bracket, 95 ... lower decontamination machine, 96 ... motor, 97 ... wire brush, 98 ... bracket, 102 ... decontamination machine, 105 ... tank, 105a to 105d ... side wall Part, 105e ... bottom, 121 to 124 ... top rail, 125 to 128 ... tooth track, 131 to 134 ... on Frame, 141 to 144 ... the lifting rail, 145-148 ... tooth rail, 151-154 ... elevating frame, 161 ... lower rail, 162 ... tooth rail, 164 ... beam, 171 ... base frame

Claims (6)

A decontamination apparatus for decontaminating the inner surface of a tank having a bottom and a side wall erected around the bottom,
An upper rail provided on the upper end of the side wall along the upper end of the side wall;
A first upper gantry moving along the upper rail;
A second upper gantry moving along the upper rail away from the first upper gantry;
A lifting rail suspended from the first upper mount along the inner surface of the side wall;
A vertical member suspended from the second upper mount along the inner surface of the side wall portion;
A lifting stand that moves up and down along the lifting rails;
A lower rail installed between the lower end of the elevating rail and the lower end of the vertical member;
A lower gantry moving along the lower rail;
A side decontamination machine provided in the elevating platform and decontaminating the inner surface of the side wall portion;
And a bottom decontamination apparatus provided in the lower mount and decontaminating the bottom.   The decontamination facility according to claim 1, further comprising an upper decontamination apparatus provided at an upper end of the vertical member or the elevating rail and decontaminating an upper end portion of an inner surface of the side wall portion.   The decontamination apparatus according to claim 1 or 2, further comprising a lower decontamination apparatus provided at a lower end of the vertical member or the elevating rail and decontaminating a lower end portion of an inner surface of the side wall portion.   The decontamination facility according to any one of claims 1 to 3, further comprising a side measuring instrument provided on the elevating platform and measuring a dose of the inner surface of the side wall portion.   The decontamination facility according to any one of claims 1 to 4, further comprising a lower measuring device provided on the lower mount and measuring the dose of the bottom. In the decontamination method of decontaminating the said tank using the decontamination installation as described in any one of Claims 1-5,
The side decontamination machine is arranged along the inner surface of the side wall by a combination of the movement of the first upper mount and the second upper mount along the upper rail and the movement of the lift mount along the lift rail. Decontaminate the inner surface of the side wall by the side decontamination machine while moving the
The combination of the movement of the first upper gantry and the second upper gantry along the upper rail and the movement of the lower gantry along the lower rail moves the bottom decontamination machine along the bottom A method of decontamination comprising decontamination of the bottom by the bottom decontamination machine.

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