JP6199705B2 - Decontamination method - Google Patents

Description

  The present invention relates to radioactive decontamination, and more particularly to a radioactive decontamination method suitable for application to a nuclear power plant.

  Equipment and piping for nuclear power plants and tools used for maintenance or repair of nuclear power plants must be disposed of after the end of their useful lives. In addition, when a nuclear power plant is decommissioned, it is necessary to dispose of floor materials and wall materials of buildings such as a reactor building and a turbine building, as well as incidental facilities in the building.

  Radioactive cobalt adheres to the reactor internal structure in the reactor pressure vessel of the nuclear power plant and the piping connected to the reactor pressure vessel. Moreover, when a part of nuclear fuel is scattered, radioactive materials such as cesium adhere to floors and walls inside the building, ground outside the building, and the building.

  When disposing of structural members and buildings of a nuclear power plant, decontamination work is necessary to remove radioactive substances adhering to the outer surface. In this decontamination work, it is necessary to avoid exposure of workers, and from this point of view, the decontamination work requires high removal performance. In addition, when an operator performs decontamination work close to the object to be decontaminated, the radioactive material should not be diffused in the surrounding area, and secondary radioactive waste other than the object to be decontaminated should not be generated as much as possible. It becomes important.

  The decontamination methods are roughly classified into two types. The first is mechanical decontamination that physically removes radioactive substances attached to the surface of the object to be decontaminated, and the second is chemical that chemically removes radioactive substances attached to the surface of the object to be decontaminated using chemicals. Decontamination. In either method, the radioactive material is removed from the outer surface of the object to be decontaminated by washing the outer surface of the object to be decontaminated or by peeling a part of the surface layer of the object to be decontaminated. Is the method. Furthermore, mechanical decontamination is classified into a wet method using a liquid such as water and a dry method using a striking tool. In the wet method, the radioactive material can be removed from the surface of the object to be decontaminated by the liquid ejected from the nozzle toward the object to be decontaminated, and the removed radioactive material can be accompanied and recovered. However, the jetted liquid itself becomes secondary radioactive waste. On the other hand, in the dry method, the decontamination work speed can be increased by increasing the destructive force such as impact, but the operability of the apparatus is lowered because the weight of the tool used is increased. Furthermore, in the dry method, the radioactive material is accompanied by dust at the time of destruction and scattered in the air, so that a facility for cleaning the surrounding air is required.

  As an example of the wet method, there is a decontamination method described in JP-A-2002-116295. In this decontamination method, a decontamination target is immersed and fixed in water in a water tank, and high-pressure water is ejected from a nozzle to decontaminate the decontamination target. Cavitation bubbles generated in the jetted water stream can be used for decontamination of the object to be decontaminated. In this method, after the decontamination with high-pressure water is completed, a decontamination agent can be added to the water in the water tank to perform chemical decontamination of the object to be decontaminated. However, the use of a decontamination agent requires a decontamination processing facility.

  Japanese Patent Laid-Open No. 2010-78539 discloses a structural member that cuts a cutting object by injecting a high-pressure water flow (jet water flow) containing a cutting aid (for example, aluminum oxide powder) from the injection nozzle toward the cutting object. The cutting method is described. The cutting aid contained in the high-pressure water flow that cuts through the cutting object and passes through the cutting object is collected in a collection container that is disposed opposite the injection nozzle with the cutting object interposed therebetween. Japanese Patent Application Laid-Open No. 7-84094 also describes a method for cutting used control rods (cutting objects) using a cutting aid. The used control rod is arranged in a region surrounded by the isolation film, and the isolation film prevents the cutting aid that cut the used control rod from being scattered around. Furthermore, cutting technology development by water jet, decommissioning technical report, 1991, shows an example in which metal, ceramics, or natural ore is used as a cutting aid.

  In the case of applying the technology of the cutting method of the cutting object using these cutting aids to the decontamination of the decontamination target, the jet pressure of the jet water stream containing the auxiliary agent is reduced to damage the decontamination target Need to avoid. However, since the distance between the spray nozzle of the spray nozzle that sprays the water flow containing the auxiliary agent and the decontamination target is kept constant, the position and material of the decontamination target cannot be set in advance. It may be difficult to decontaminate without damaging the object to be decontaminated. Furthermore, in these methods, a method for collecting the auxiliary agent is described, but a method for setting the injection condition of the jet water flow for the complicated decontamination target and a method for collecting the auxiliary agent have not been studied.

  In the decontamination method described in JP 2013-113593 A, a jet water flow is jetted from a jet nozzle toward a decontamination target, and the surface of the decontamination target is decontaminated by the jet water flow. Furthermore, carbon dioxide gas is blown into the water before being jetted from the jet nozzle, and the pH of this water is lowered. That is, water becomes acidic. The acidified water is sprayed from the spray nozzle, and the decontamination object is decontaminated.

JP 2002-116295 A JP 2010-78539 A Japanese Patent Laid-Open No. 7-84094 JP 2013-113593 A

Development of cutting technology by water jet, decommissioning technical report, 1991

  When considering the decontamination work in a high-dose place, the inventors need a remote decontamination work, so that the wet process can utilize the advantages of being relatively lightweight and having less dust scattering in the air. We focused on the decontamination method.

  In order to improve the decontamination efficiency of radioactive substances attached to the decontamination target in the conventional decontamination method using a water stream, the inventors have increased the amount of water in the jet stream, And a method of mixing solids such as metals and ores as a decontamination aid into the jet water stream were studied. However, in the conventional decontamination method, when using a jet stream containing chemicals or auxiliaries to improve the decontamination efficiency, the distance between the decontamination object and the inside of the injection nozzle and the material of the decontamination object are unknown. In such a case, there is a possibility of damaging the decontamination object itself. Also, when keeping the distance between the spray nozzle outlet and the object to be decontaminated at the time of decontamination, prepare multiple high-pressure water pumps etc. to change the water pressure according to the object to be decontaminated It may be necessary to do.

  In addition, since the recovery of the water of the jet stream used for decontamination conventionally injects the jet water stream from the spray nozzle close to the object to be decontaminated, the recovery mainly sucks water in the vicinity of the spray nozzle. Is done by. However, when the distance between the spray nozzle and the object to be decontaminated is long, the suction method cannot be applied.

  The objective of this invention is providing the decontamination method which can improve the decontamination efficiency of the decontamination target object.

The feature of the present invention that achieves the above-described object is that when the water flow pressurized by the pump and sprayed from the spray nozzle hits the object to be decontaminated, the pressure P _b of the water flow and the radioactive material adheres from the spray nozzle. The rate of decrease in the pressure of the water flow corresponding to the distance to the decontamination position of the decontamination object, the rate of decrease in the amount of water in the water flow corresponding to the diameter of the injection nozzle of the injection nozzle, and the injection nozzle connected to the pump the first pressure P _a, which is determined based on the pressure loss of the hose which corresponds to the length of the hose leading to the water, setting the discharge pressure of the pump,
The water in the first pressure P _a discharged from the pump, and injected from the injection nozzle as water guided to the injection nozzle through the hose,
The purpose is to remove radioactive substances adhering to the object to be decontaminated by the jetted water flow.

The pressure P _b of the water flow when the water flow injected from the injection nozzle hits the decontamination object, and the water flow corresponding to the distance from the injection nozzle to the decontamination position of the decontamination object to which the radioactive substance is attached reduction rate of pressure decrease rate of water in the water flow, and the pressure P _a, which is determined based on the pressure loss of the hose leading to the water is connected to a pump to the injection nozzle, the discharge of the pump to supply water to the injection nozzle since setting the pressure, it is possible to maintain the pressure P _b of the water flow hitting the decontamination object, thereby improving the decontamination efficiency of the decontamination object.

Preferably the, R ₁ and the reduction rate of the pressure of the water flow, the reduction rate k ₁ of water of the water flow, and when the pressure loss and k _2, the first pressure P _a is the following formula ( It is desirable to be obtained in 1).

P _a = P _b × 1 / R ₁ × k ₁ × 1 / k ₂ (1)
Preferably, it is desirable to set within the allowable pressure corresponding pressure P _b in the material of the decontamination object. For this reason, damage of the decontamination target object by the jetted water flow can be prevented.

According to the present invention, the reduction rate of the pressure of the discharge pressure of the pump water flow, reduces the proportion of water in the water flow, and because it is set to the pressure P _a, which is determined based on the pressure loss of the hose, with water removal The decontamination efficiency of the object to be dyed can be improved.

It is a flowchart which shows the procedure of the first half in the decontamination method of Example 1 which is one suitable Example of this invention. 3 is a flowchart showing a procedure in the latter half of the decontamination method of Example 1. It is explanatory drawing which shows the decontamination method of Example 1 implemented using a decontamination apparatus. It is a block diagram of the decontamination water supply apparatus of the decontamination apparatus shown in FIG. 2, and the operating device of the decontamination apparatus. It is explanatory drawing which shows the allowable water pressure of a jet water flow corresponding to the material of the decontamination object. It is explanatory drawing which shows the decreasing rate of the water pressure of the jet water flow corresponding to the distance from a jet nozzle to a decontamination target object. It is explanatory drawing which shows the relationship between the removal rate of a radioactive substance, and the water pressure of a jet water flow when it hits a decontamination target object. It is explanatory drawing which shows each relationship between the diameter of the jet nozzle of a jet nozzle, the amount of water of a jet water flow, the length of a hose, and a pressure loss. It is a flowchart which shows the procedure of the first half in the decontamination method of Example 2 which is another suitable Example of this invention. 6 is a flowchart showing a procedure in the latter half of the decontamination method of Example 2. It is explanatory drawing which shows the decontamination method of Example 2 implemented using a decontamination apparatus. It is explanatory drawing which shows the decontamination method of Example 2 implemented using another decontamination apparatus. It is a flowchart which shows the procedure of the first half in the decontamination method of Example 3 which is another suitable Example of this invention. 10 is a flowchart showing a latter half procedure in the decontamination method of Example 3. It is explanatory drawing which shows the decontamination method of Example 3 implemented using a decontamination apparatus. It is a flowchart which shows the procedure of the first half in the decontamination method of Example 4 which is another suitable Example of this invention. It is a flowchart which shows the procedure of the latter half in the decontamination method of Example 4. It is explanatory drawing which shows the decontamination method of Example 4 implemented using a decontamination apparatus.

  Examples of the present invention will be described below.

  The decontamination method of Example 1, which is a preferred example of the present invention, will be described with reference to FIGS. 1A, 1B, 3 and 4. FIG.

  First, the decontamination apparatus used for the decontamination method of a present Example is demonstrated using FIG.3 and FIG.4. The decontamination apparatus 1 includes an ejection nozzle moving device 2, a dose rate meter 8, a decontamination water supply device 11, a camera monitor operation panel 20, a decontamination apparatus operation panel 22, and a computer 23. The injection nozzle moving device 2 includes a moving carriage 9, an injection nozzle lifting / lowering device 4, an injection nozzle 5, and cameras 6 and 7.

  The movable carriage 9 has four wheels 3 and has a motor (not shown) that rotates the wheels 3. An injection nozzle lifting / lowering device 4 configured by connecting a plurality of telescopic cylinders that extend vertically is installed on the upper surface of the movable carriage 9. The outer diameter of the expansion / contraction cylinder located above the injection nozzle lifting / lowering device 4 is smaller. The injection nozzle 5 and the camera 6 are installed in the telescopic cylinder of the injection nozzle lifting / lowering device 4 at the uppermost position. A dose rate meter 8 is installed on the upper surface of the camera 6. A camera 7 is installed on the moving carriage 9 on the traveling direction side.

  The decontamination water supply device 11 includes a water supply pump 10, a water supply hose 18, and a water supply tank 54. The water supply hose 18 connected to the water supply tank 54 is attached to the movable carriage 9, arranged along the injection nozzle lifting / lowering device 4, and connected to the injection nozzle 5. A water supply pump 10 is provided in the water supply hose 18. The water supply hose 18 is wound around the hose drum 17. The water supply pipe 13 is connected to the water supply tank 54, and the open / close valve 14 and the pump 12 are provided in the water supply pipe 13. A water level meter 15 is installed in the water supply tank 54. The water level meter 15 is connected to the control device 16, and the control device 16 is connected to the on-off valve 14 and the pump 12.

  A cable 25 connected to the decontamination device operation panel 22 is connected to the movable carriage 9. A cable 26 connected to the camera monitor operation panel 20 is connected to each of the cameras 6 and 7. The cables 25 and 26 are wound around the cable drum 24. Cables 25 and 26 are multicore cables. A display device 21 is provided on the camera monitor operation panel 20. A computer 23 is connected to the camera monitor operation panel 20.

  The camera monitor operation panel 20, the decontamination apparatus operation panel 22, the computer 23, and the water supply tank 54 are installed outside the reactor building in a place where there is little risk of exposure to the operator.

  The decontamination object which decontaminates using the decontamination apparatus 1 is demonstrated. The decontamination target is assumed to be a plate-like member (for example, a ceiling panel) 34 existing in a building, for example, a room 30 in the reactor building. The room 30 is surrounded by a floor 31, side walls 32 and a ceiling 33. The plate-like member 34 is attached to the ceiling 33 of the room 30 by support members 36 and 37. A plurality of pipes 35 are disposed between the plate member 34 and the ceiling 33 and supported by the plate member 34.

  For example, the decontamination of the portion of the plate-shaped member 34 to which the radioactive substance 38 is attached is performed by increasing the pressure of the water in the water supply tank 54 with the water supply pump 10, and the pressure-increased water from the injection nozzle 5 through the water supply hose 18. This is performed by spraying toward the position where the radioactive substance 38 of the member 34 is attached. Such a decontamination method of the present embodiment using the decontamination apparatus 1 will be described with reference to FIGS. 1A and 1B.

A decontamination target area is set (step S1). In order to set the decontamination target region, the operator operates the decontamination apparatus operation panel 22 to display the reactor building CAD data stored in the storage device (not shown) of the computer 23 on the display device 21. . The operator selects one room 30 in the reactor building where decontamination work is performed while viewing the displayed CAD data, and sets this room 30 as a decontamination target area. The injection nozzle moving device 2 that performs decontamination in the room 30 that is the decontamination pair target region is moved to the room 30 where the decontamination target exists through the passage in the reactor building. This movement is effected by the operator to operate the decontamination unit operation panel 2 2 drives a motor provided in the movable carrier 9 to rotate the wheel 3. An image in front of the moving carriage 9 captured by the camera 7 provided on the moving carriage 9 is transmitted to the display device 21 through the cable 26 and displayed on the display device 21. The operator moves the decontamination apparatus operation panel 2 2 by operating the injection nozzle moving apparatus 2 while viewing the image displayed on the display device 21 to the target room 30. The spray nozzle moving device 2 is in a state where the telescopic cylinder is contracted and the spray nozzle 5 is positioned at the lowest position in order to easily move while moving to the room 30.

  When the direction of the camera 7 is changed, the operator operates the camera monitor operation panel 20. A camera operation signal is transmitted from the camera monitor operation panel 20 to the driving device (not shown) of the camera 7 through the cable 26, and the direction of the camera 7 is changed by driving the driving device. A driving device for the camera 7 is provided in the movable carriage 9.

The dose rate in the decontamination target area is measured (step S2). The movable carriage 9 is moved along the upper surface of the floor 31 (hereinafter referred to as the floor surface), and the dose rate of the plate member 34 and the like is measured by the dose rate meter 8. The dose rate meter 8 detects the radiation emitted from the radioactive substance attached to the plate-like member 34 and the like, and obtains the dose rate of the target member based on the radiation detection signal. The movable carriage 9 is moved along the floor in the room 30 and the dose rate A ₁ at each position in the room 30 is measured.

If necessary, the dose rate meter 8 is raised so as to be close to the plate member 34 to some extent, and the dose rate of the plate member 34 and the like is measured. Increase in the dose rate meter 8, the operator drives the injection nozzle elevating device 4 of the injection nozzle moving device 2 that exists by operating the decontamination device pendant 2 2 room 30, expansion pipe of the injection nozzle elevating device 4 It is done by stretching. Such an increase in the injection nozzle 5, the image displayed on the display device 21 is captured by the camera 6 the operator is performed by operating the decontamination device control panel 2 2 while watching. When the dose meter 8 has risen to a predetermined position, the operator stops the rise of the injection nozzle elevating device 4 by operating the decontamination device control panel 2 2.

It is determined whether decontamination is necessary based on the measured dose rate (step S3). The dose rate A ₁ measured by the dose rate meter 8 is transmitted to the display device 21 through the cable 25 and displayed. The operator looks at the displayed dose rate A ₁ and determines whether this dose rate A ₁ is larger than the set dose rate A ₀ . When the dose rate A ₁ is less than or equal to the set dose rate A _0, it is determined whether the decontamination work in the room is complete (step S16). When the decontamination work in the room 30 is not completed (when the determination in step S16 is “No”), the movable carriage 9 is moved and the dose rate meter 8 is moved by operating the decontamination apparatus operation panel 22. Then, the dose rate of the plate-like member 34 at different positions is measured (step S2). When the dose rate A ₁ is larger than the set dose rate A ₀ (A ₀ <A ₁ ), it is necessary to decontaminate the position where A ₀ <A ₁ .

Construction records, drawings and images are displayed on the display device (step S4). When the operator operates the decontamination device operation panel 22, the construction record and the drawing information stored in the storage device of the computer 23 are read and displayed on the display device 21. Still image information of a video taken by the camera 6 when the dose rate A ₁ is measured is also displayed on the display device 21.

The position of the radiation source is specified (step S5). Operator drawing displayed on the display device 21 (CAD data) and look at each information of the still image of the image captured by the camera 6, a position where the dose rate A ₁ is larger than the set dose rate A _0, That is, the position of the radiation source (position where the radioactive substance is attached) is specified. CAD data is used as drawing information. Furthermore, the distance D ₀ between the injection port of the injection nozzle 5 and the position of the radiation source is set to the height from the floor of the injection port of the injection nozzle 5 and the specified position where the radioactive substance 38 is attached. Obtained using each information. The distance D ₀ includes a distance in the horizontal direction and a distance in the height direction. The obtained distance D ₀ is a guide for the movement of the injection nozzle 5 in step S8. The position of the radiation source specified in step S5 is a position where the radioactive substance 38 shown in FIG. 2 exists. A position where the radioactive substance 38 is present is a decontamination area where decontamination should be performed.

  It is determined whether the decontamination area is wide (step S6). Based on the extent of the radiation source position (position where the radioactive substance 38 is attached) obtained in step S5, it is determined whether the decontamination region is wide. When the decontamination region is a range narrower than the set range (when the determination in step S6 is “No”), a radiation shielding body is installed (step S7). Since the decontamination region is narrow, radiation shielding using a radiation shielding body is easy. A radiation shielding body is carried into the room 30, and an operator installs a radiation shielding body (not shown) below the plate-like member 34 so as to shield the radiation from the radiation source (radioactive material 38). Decontamination is not performed on the above-described narrow decontamination region facing the installed radiation shield. Then, the completion of the decontamination work in the room 30 is determined (step S16). There is a possibility that the position of the radiation source to be decontaminated also exists in the room 30. When the decontamination work in the room 30 is not completed by decontamination of the target radiation source, as described above. In step S2, the dose rate of the plate-like member 34 at different positions is measured.

When the determination in step S6 is “Yes”, that is, when the decontamination area is wide, the spray nozzle of the decontamination apparatus is moved (step S8). If the decontamination area is larger than the set range and wide, the area where the radiation shield is installed becomes wider in step S7, and it takes a long time to install the radiation shield. In this case, decontamination in step S11 is performed without installing a radiation shield. Steps S8 to S10 are decontamination preparation steps in step S11. In the process step S8, the operator, taking into account the distance D ₀ calculated in step S5, decontamination while watching the image displayed on the display device 21 loaded with the cameras 7 and 6 device control panel 2 2 Is operated to move the injection nozzle moving device 2 along the floor surface and further raise the injection nozzle lifting device 4. When the spray nozzle 5 reaches near the position of the plate-like member 34 to which the radioactive substance 38 is adhered due to the movement of the spray nozzle moving device 2 and the lift of the spray nozzle lifting / lowering device 4, the spray nozzle moving device 2 The movement and the raising of the injection nozzle lifting / lowering device 4 are stopped.

  The material of the decontamination object is specified by adjusting the angle of the spray nozzle and the distance from the spray nozzle to the position where the radioactive substance 38 is attached (step S9). After the injection nozzle 5 is moved in step S8, this injection is performed on the basis of the position where the radioactive substance 38 specified in step S5 is attached and the position of the injection port of the injection nozzle 5 whose rise is stopped in step S8. The computer 23 calculates the angle of the injection nozzle 5 when the mouth faces the position where the radioactive substance 38 is attached. The angle of the injection nozzle 5 calculated by the computer 23 is displayed on the display device 21. By operating the decontamination device operation panel 22 based on the angle of the spray nozzle 5 displayed by the operator, an angle adjustment command is output from the decontamination device operation panel 22 to the cable 25. Although not shown, the swinging device of the injection nozzle 5 attached to the upper end of the telescopic cylinder positioned at the uppermost position is driven based on the angle adjustment command, and the angle of the injection nozzle 5 is set to the calculated angle. Adjusted.

The computer 23 calculates a distance D ₁ between the ejection port of the ejection nozzle 5 and the position of the radiation source after adjusting the angle of the ejection nozzle 5. Calculation of the distance D ₁ may be determined using the information of the position where the position of the injection nozzle 5 (height and horizontal position of the floor face of the injection port), and radioactive materials 38 are attached. The material of the decontamination object, that is, the material of the plate-like member 34 to which the radioactive substance 38 is attached can be confirmed by CAD data displayed on the display device 21. The material of the plate member 34 is, for example, resin.

To set the scanning speed of the pressure P _a and the injection nozzles of the water discharged from the water feed pump (step S10). Information on the allowable water pressure of the jet water flow corresponding to the material of the decontamination object shown in FIG. 4 and the decrease in the water pressure of the jet water flow corresponding to the distance from the jet nozzle to the decontamination target shown in FIG. Information indicating the change in the ratio, information indicating the relationship between the removal rate of the radioactive substance having the scanning speed of the injection nozzle as a parameter and the water pressure of the injection water flow shown in FIG. 6, and the injection nozzle shown in FIG. Information indicating the relationship between the diameter of the nozzle and the amount of water in the jet water flow and information indicating the relationship between the length of the water supply hose and the pressure loss are stored in the storage device of the computer 23.

The pressure P _a is a pressure of the water has been pressurized by the feed water pump 10, a discharge pressure of the feed water pump 10. When setting the pressure P _a of the injection water stream 55 is decontaminated object (e.g., a plate-like member 34) (or less than the allowable pressure P ₁₎ water pressure P _b of the injection water stream 55 when hitting the, is injected from the injection nozzle 5 It is necessary to obtain the ratio R ₁ of the water pressure of the jet water flow 55 and the correction coefficients k ₁ and k ₂ that are reduced before hitting the object to be decontaminated.

In setting the discharge pressure P _a and the scanning speed of the injection nozzle of the water supply pump 10, the operator operates the decontamination device control panel 2 2, shown in FIGS. 4 to 7 stored in the storage device Each information is read out sequentially and displayed on the display device 21 sequentially. When the information shown in FIG. 4 is displayed on the display device 21, the operator, based on the displayed information, the material of the plate member 34 identified in step S9, that is, the resin plate member 34. An allowable water pressure P ₁ of the jet water flow with respect to is obtained.

Moreover, the water pressure of the jet water flow 55 jetted from the jet port of the jet nozzle 5 decreases until the jet water flow 55 reaches the position where the radioactive substance 38 is attached from the jet port. The operator displays the ratio R _{1 in} which the water pressure of the jet water flow 55 when jetted from the jet port of the jet nozzle 5 is reduced to the position where the radioactive substance 38 is attached is displayed on the display device 21 as shown in FIG. and determining based on the distance D _1.

The operator looks at the information shown in FIG. The operator uses the injection nozzle 5 necessary to achieve the DF ₁ (A ₁ / A ₀ ) necessary for making the dose rate A ₁ at the position where the radioactive substance 38 is attached equal to or less than the set dose rate A _0. scanning speed and the injection water 55, the water pressure P _b when striking the decontamination object, determined using the information shown in FIG. That is, the high pressure H as the scanning speed of the spray nozzle 5 and the water pressure P _L as the water pressure P _b when the spray water flow 55 hits the plate-like member 34 that is the decontamination object at the high speed H scanning speed of the spray nozzle 5, respectively. Selected. The water pressure P _L is smaller than the allowable water pressure P ₁ of the resin plate member 34.

Depending on the diameter (inner diameter) of the injection nozzle 5 and the length of the water supply hose 18 connected to the injection nozzle 5, the water pressure of the injection water flow injected from the injection nozzle 5 changes. For this reason, the information which shows the relationship between the diameter of the injection nozzle of the injection nozzle shown in FIG. 7 and the amount of water of the injection water flow, and the information which shows the relationship between the length of the water supply hose connected to the water supply pump 10 and the pressure loss 21. Based on the diameter of the injection port of the injection nozzle 5 provided in the injection nozzle moving device 2, the operator changes the diameter of the injection port from the information indicating the relationship between the displayed diameter of the injection nozzle and the amount of water in the injection water flow. obtains a reduction ratio k ₁ of water injection water flow due to further water supply based on the length of the water supply hose 18 pulled out from a hose drum 17, the information indicating the relationship between the length and the pressure loss of the water supply hose which is displayed A pressure loss k ₂ corresponding to the length of the hose 18 is obtained.

In order to obtain the pressure _{b of the} jet water flow 55 that is required when sprayed from the jet port of the jet nozzle 5 provided in the jet nozzle moving device 2 and hits the position of the plate-like member 34 where the radioactive substance 38 is adhered. the must be set to a value calculated based on the discharge pressure P _a of the following equation of the feed water pump 10 (1). Discharge pressure P _a of the feed water pump 10, the water pressure P _b when the hit to the plate-like member 34 is a decontamination object obtained by the information displayed on the display device 21, the pressure of the injected water jet Each of the reduction rate R ₁ , the reduction rate k _1, and the pressure loss k ₂ can be obtained by substituting into the equation (1).

P _a = P _b × 1 / R ₁ × k ₁ × 1 / k ₂ (1)
As described above, since the water pressure P _L is selected as the water pressure P _b when the jet water flow 55 hits the plate-like member 34 as the decontamination target at the high scanning speed H of the jet nozzle 5, the formula ( By substituting the water pressure P _L as the water pressure P _b in 1), the discharge pressure P _a1 (= P _L × 1 / R ₁ × k) of the water supply pump 10 when the scanning speed of the injection nozzle 5 is set to the high speed H described above. ₁ × 1 / k ₂ ) is required.

Note that P _b × 1 / R ₁ is the pressure of the jet water flow 55 at the time of injection from the injection port of the injection nozzle 5, and P _b × 1 / R ₁ × k ₁ flows into the injection port of the injection nozzle 5. It is the pressure of water just before .
Decontamination is performed (step S11). The discharge pressure of the feed water pump 10 is set to the pressure _Pa1 . The operator drives the water supply pump 10 by operating the decontamination device control panel 2 2. Water in the water supply tank 54 is boosted to a pressure _Pa1 by the water supply pump 10 and supplied to the injection nozzle 5 through the water supply hose 18, and becomes an injection water flow 55 from the injection port of the injection nozzle 5. It is injected toward the position where the radioactive substance 38 is attached. By setting the discharge pressure P _a of the feed water pump 10 to the pressure P _a1, pressure P _b of the injection water stream 55 which hit positions radioactive material 38 of the plate-like member 34 is attached is the water pressure P _L. The radioactive material 38 adhering to the plate member 34 is washed away by the jet water flow 55. By driving a motor provided in the moving carriage 9, the moving carriage 9 is moved at the high speed H obtained in step S10 while injecting the jet water flow 55 from the injection port of the injection nozzle 5. In order to operate the injection nozzle 5 at a high speed H, the rotational speed of the motor provided in the movable carriage 9 is adjusted. The plate member 34 is decontaminated by the jetted water flow 55 while moving the movable carriage 9. The jetted water stream 55 hits the plate-like member 34 and decontaminates, and then falls toward the floor 31. The dropped water is discharged from a drain port (for example, the drain port 45 shown in FIG. 10) formed in the floor 31 to an external tank (not shown).

  The water level in the water supply tank 54 is measured by the water level meter 15, and the water level measured by the water level meter 15 is input to the control device 16. When it is determined that the water level in the water supply tank 54 has dropped due to the injection of the jet water flow 55 and the water level measured by the control device 16 has fallen below the lower limit set water level, the control device 16 opens the on-off valve 14 and pumps. 12 is driven. For this reason, water is replenished into the water supply tank 54 through the water supply pipe 13. When the water level in the water supply tank 54 rises and the water level measured by the water level gauge 15 reaches the upper limit set water level, the control device 16 stops driving the pump 12 and closes the on-off valve 14. The supply of water into the water supply tank 54 is stopped.

When decontamination of a predetermined portion of the plate-like member 34 is completed, the operator the water supply pump 10 is stopped by operating the decontamination device control panel 2 2, stops injection of the injection water stream 55 from the injection nozzle 5.

The dose rate is measured (step S12). The dose rate meter 8 measures the dose rate A ₂ in the area where decontamination has been performed by jetting the jet water flow 55. The dose rate A ₂ measured after carrying out decontamination is lower than the dose rate A ₁ before carrying out decontamination.

It is determined whether decontamination is necessary based on the dose rate measured again (step S13). The dose rate A ₂ measured again by the dose rate meter 8 is displayed on the display device 21. The operator determines whether this dose rate A ₂ is larger than the set dose rate A ₀ . When the dose rate A ₂ is less than or equal to the set dose rate A ₀ , the completion of the decontamination work in the room is determined (step S16). When the decontamination work in the room 30 is not completed (when the determination in step S16 is “No”), the movable carriage 9 is moved and the dose rate meter 8 is moved by operating the decontamination apparatus operation panel 22. Then, the dose rate of the plate-like member 34 at different positions is measured (step S2). If the dose rate measured at a different position is greater than the set dose rate A ₀ , it is necessary to decontaminate that position.

In step S13, when it is determined that the dose rate A ₂ is larger than the set dose rate A ₀ (A ₀ <A ₂ ), the pressure _{Pa 1 of the} water discharged from the water supply pump and the scanning speed of the injection nozzle are changed. (Step S14). The scanning speed of the injection nozzle 5 is changed to the medium speed M shown in FIG. 6, and the decontamination rate of the plate-like member 34 is increased from DF ₁ to DF ₂ . Therefore, the plate-like member 34, the water pressure P _b of the injection water stream 55 when hitting the positions radioactive material 38 is adhered to the allowable pressure P ₁ following example hydraulic _{P M (P L <P M} ) ( Fig. 6). Therefore, the pressure P _a of the water discharged from the water supply pump 10, for example, a high pressure _{P a2 (= P M × 1} / R 1 × than the pressure P _a1 which is set on the basis of the pressure P _L in step S10 k ₁ × 1 / k ₂ ). Decontamination is performed (step S15). Similarly to step S11, the feed water pump 10 is driven to inject the injection water flow 55 from the injection nozzle 5, and the removal of the position where the radioactive material 38 of the plate-like member 34 is injected, which has injected the injection water flow 55 in step S11. Dyeing. At this time, water pressure P _b of the injection water flow 55 when hitting the plate member 34 so that the water pressure P _M, the discharge pressure P _a of the water supply pump is set to the pressure P _a2. The motor provided in the movable carriage 9 is driven, and the movable carriage 9 is moved at the medium speed M while ejecting the jet water flow 55 from the ejection port of the ejection nozzle 5. The injection nozzle 5 is also moved at a medium speed M. The position of the plate member 34 decontaminated in step S11 is decontaminated again. When the decontamination in step S15 is completed, the supply of water to the spray nozzle 5 is stopped.

After the decontamination in step S15 is completed, the dose rate is measured in step S12, and the determination in step S13 using this dose rate is performed. When the measured dose rate becomes equal to or less than the set dose rate A ₀ , it is determined in step S16 that the decontamination work in the room 30 has been completed. If it is determined in step S13 that the measured dose rate is greater than the set dose rate A ₀ , the steps S14, S15, S12, and S13 are performed in step S13. It repeats until it determines with it being the setting dose rate _A0 or less. Decontamination at step S15 in this case, the injection nozzle 5 is scanned at a low speed L, as the water pressure P _b of the injection water stream 55 is high water pressure P _H than the water pressure P _M when hitting the plate member 34, discharge pressure P _a feedwater pump is performed is set to a higher pressure _{a3 (= P H × 1 /} R 1 × k 1 × 1 / k 2) than the pressure P _a2. Water pressure P _H is the allowable pressure P ₁ the following water pressure water jet streams to the resin-made plate member 34.

The measured dose rate in step S13 is determined to be equal to or less than set dose rate A _0, when the determination in the subsequent step S16 is "No", until the determination of step S16 is "Yes", Step S2~ The corresponding step is repeated among the steps of S15. When the determination in step S16 is “No”, the operation of the decontamination apparatus operation panel 22 moves the moving carriage 9 to move the dose rate meter 8 to move the dose rate meter 8 in a different position (for example, the radioactive substance 38A is present in the room 30). The dose rate of the plate member 34 at the adhering position) is measured (step S2). Since the radioactive substance 38A is attached, the determination in step S3 is “Yes”, and the steps S4 and S5 are performed. In step S5, the position where the radioactive substance 38A is attached is specified. For example, when the determination in step S6 is “No”, then steps S8, S9, and S10 are sequentially performed. In step S11, the injection water flow 55 is supplied from the injection nozzle 5 to the plate-like member 34. , And spray toward the position where the radioactive substance 38A is attached. After the decontamination in step S11 is completed, steps S12 and S13 are performed. When the determination in step S13 is “No”, the determination in step S16 is subsequently performed. When the determination in step S16 is “Yes”, the decontamination work in the room 30 ends.

  In the present embodiment, the position where the radioactive substance 38 is adhered (the position of the radiation source) in the room 30 can be easily specified using the CAD data and the still image of the captured video.

In this embodiment, the operator confirms the material of the plate-like member 34, which is a decontamination target to which the jet water flow 55 is applied at the time of decontamination, using the CAD data displayed on the display device 21, and corresponds to the material. The allowable water pressure P ₁ of the jet water flow 55 can be confirmed based on the information shown in FIG. For this reason, at the time of decontamination of the plate-like member 34, the water pressure of the jet water flow 55 when hitting the plate-like member 34 that is the object to be decontaminated can be set to the allowable water pressure P ₁ or less. Damage to the shaped member 34 can be prevented.

In the present embodiment, the water pressure of the jet water flow 55 jetted from the jet nozzle 5 based on the distance from the jet port of the jet nozzle 5 to the position (radiation source position) of the plate-like member 34 where the radioactive substance 38 is attached. The reduction rate R ₁ is obtained, and the water pressure P _b (for example, the water pressure P _L , the water pressure P _M, or the water pressure P _H ) when the jet water flow 55 hits the plate-like member 34 that is the object of decontamination is obtained. A reduction rate k ₁ of the water amount of the jet water flow 55 due to the diameter of the jet port is obtained, and further, a pressure loss k ₂ of the water supply hose 18 corresponding to the length of the water supply hose 18 is obtained. According such a present embodiment, the injection water flow 55, pressure P _b when striking the plate member 34 is a decontamination object, reduction rate R ₁ of the pressure water jets 55, reduction in the amount of water injection water stream 55 ratio k _1, and the pressure P _a, which is determined based on the pressure loss k ₂ of the water supply hose 18 (formula (pressure P _a obtained by using 1)), the water supply pump 10 supplies water to the injection nozzle 5 since setting the discharge pressure, it is possible to maintain the pressure P _b of the injection water stream 55 when hitting the plate member 34, thereby improving the decontamination efficiency of the plate-like member 34. The pressure P _b is the allowable pressure P ₁ or less, it is possible to prevent damage to the plate-like member 34 due to the injection water stream 55.

When the dose rate A ₂ measured in step S12 is determined in step S13 that the dose rate A ₂ is larger than the set dose rate A ₀ (A ₀ <A ₂ ), the water pressure P _b is higher than the water pressure P _L. to be changed to the water pressure P _M, the discharge pressure of the feed water pump 10 is changed to a high pressure P _a2 than the pressure P _a1. Along with such a change in the discharge pressure of the water supply pump 10, the scanning speed of the injection nozzle 5 is changed from the high speed H to the medium speed M. In After changing the discharge pressure and the scanning speed of the feed water pump 10, the injection nozzle 5 is scanned at a medium speed M, since the water pressure of water jets 55 when hitting the plate member 34 is pressure P _M, the plate-like member The position where 34 radioactive substances 38 are attached can be decontaminated with the jet water flow 55 having a high water pressure at a low scanning speed. For this reason, the decontamination efficiency is improved as compared with the case where the spray nozzle 5 is scanned at a high speed H and decontaminated at a water pressure P _L lower than the water pressure P _M.

  In this embodiment, since the material of the plate-like member 34 that is a decontamination object is grasped using CAD data, it is easy to grasp the material of the decontamination object.

Also pressure of the injection water stream 55 is subjected to decontamination comprising water pressure P _H, the dose rate A ₁ of decontamination position of the plate member 34 is set at the time of the injection nozzle 5 is scanned at a low speed L hits the plate-like member 34 When the dose rate A ₀ does not fall below the water pressure of the jet water flow 55 when it hits the plate member 34, it is possible to make the water pressure larger than the allowable water pressure P ₁ .

  The decontamination method of Example 2, which is another preferred embodiment of the present invention, will be described with reference to FIGS. 8A, 8B and 9. FIG. In the decontamination method of the present embodiment, a decontamination waste liquid recovery device 27 is used in addition to the decontamination device 1 used in the decontamination method of Example 1. A schematic configuration of the decontamination waste liquid recovery device 27 will be described.

Decontamination waste liquid recovery device 27 is provided with a collection hood 29 in which a plurality of wheels 3 rotatably mounted on a movable carrier 9 divided attached to A dyeing waste liquid recovery container 28, and decontamination waste liquid collecting container 28 which is provided ing. The movable carrier 9 A decontamination waste liquid recovery unit 27, although not shown, are provided movable carriage 9 similarly to camera 7 of the decontamination apparatus 1. The spray water flow 55 sprayed from the spray nozzle 5 of the decontamination apparatus 1 and hitting the decontamination position of the plate-shaped member 34 becomes a large number of water droplets 39 and falls toward the floor 31 in the room 30. The decontamination waste liquid collection container 28 of the decontamination waste liquid collection device 27 collects these falling water droplets.

  Such a decontamination method of the present embodiment using the decontamination apparatus 1 and the decontamination waste liquid recovery apparatus 27 will be described with reference to FIGS. 8A and 8B. The decontamination method of the present embodiment is a decontamination method in which two steps S17 and S18 are added to the decontamination method of the first embodiment. Other steps in the decontamination method of this example are the same as those of the decontamination method of Example 1.

In the decontamination method of the present embodiment, steps S1 to S6 and S8 to S9 performed in the first embodiment are sequentially performed. The installation of the radiation shield in step S7 is performed when the determination in step S6 is “No”. After the process of step S9 is completed, the decontamination water collection container is moved (step S17). Other motor provided in the mobile carriage 9 A decontamination waste liquid recovery unit 27 (not shown) is driven, it is moved along the moving carriage 9 A floor 31. By moving the movable carriage 9 </ b> A, the decontamination waste liquid collection container 28 is disposed immediately below the decontamination position of the plate-like member 34. The angle of the collection hood is adjusted and the drainage groove is sealed (step S18). A motor (not shown) provided in the decontamination waste liquid recovery container 28 is driven, and a recovery hood 29 rotatably attached to the decontamination waste liquid recovery container 28 is rotated. As the collection hood 29 rotates, the decontamination waste liquid collection container 28 is opened upward. The rotation angle of the collection hood 29 is adjusted by driving the motor so that the opening angle between the collection hood 29 and the decontamination waste liquid collection container 28 becomes a predetermined opening angle. When the opening angle reaches a predetermined angle, the rotation of the collection hood 29 is stopped.

  In step S11, as in the first embodiment, decontamination of the position where the radioactive substance 38 of the plate-like member 34 is attached is performed. At the time of decontamination, the jet water flow 55 jetted from the jet nozzle 5 is applied to the plate member 34. The jet water flow 55 hitting the plate member 34 becomes a large number of water droplets 39 and falls toward the floor 31. The falling water drops 39 are collected in the decontamination waste liquid collection container 28 of the decontamination waste liquid collection device 27.

  After the decontamination of the decontamination area is completed, steps S12 and S13 are performed. When the determination in step S13 is “Yes”, the steps S14, S15, S12, and S13 are repeated until the determination in step S13 becomes “Yes”, as in the first embodiment. When the determination in step S3 or S13 is “No” and the determination in step S16 is “Yes”, the decontamination work in one room is completed.

In the present embodiment, each effect produced in the first embodiment can be obtained. This embodiment, for collecting water droplets 3 9 falling during decontamination in decontamination waste liquid collecting container 28 of the decontamination waste liquid recovery device 27, water droplets 39 fall onto the floor 31 is significantly reduced. For this reason, the contamination of the floor 31 surface by the falling water droplet 39 is reduced.

  Instead of the decontamination waste liquid recovery apparatus 27, a decontamination waste liquid recovery apparatus 40 shown in FIG. 10 may be used. The decontamination waste liquid recovery device 40 has a configuration in which a suction device 41 having a suction nozzle (not shown) is provided in a movable carriage 2B provided with a plurality of wheels 3. A monitoring camera 42 is provided in the suction device 41. In the decontamination method using the decontamination apparatus 1 and the decontamination waste liquid recovery apparatus 40, the drainage port 45 formed in the floor 31 is sealed by the sealing plate 44 at the time of decontamination. Water droplets 39 that have fallen due to the spray water flow 55 hitting the plate-like member 34 at the time of decontamination in step S11 and the like collect in the vicinity of the drain port 45 of the floor 31. The water 43 collected in the vicinity of the drain port 45 is sucked from the suction nozzle by the suction device 41 of the decontamination waste liquid recovery device 40. The sucked water is discharged to an external tank (not shown) through a hose connected to the suction device 41. The water 43 sucked by the suction device 41 may be collected in a tank (not shown) provided in the decontamination waste liquid collection device 40.

The decontamination method of Example 3, which is another preferred embodiment of the present invention, will be described with reference to FIGS. 11A, 11B and 12. FIG. In the decontamination method of the first embodiment, the jet water stream 55 is jetted from the jet nozzle 5 toward the decontamination target. However, in the decontamination method of this embodiment, in addition to the decontamination using the jet water stream 55, a chemical (for example, Further, decontamination can be performed by spraying water containing a surfactant-containing chemical and oxalic acid from the spray nozzle 5. For this reason, the decontamination apparatus used in the present embodiment is another water supply in which a chemical supply apparatus (not shown) is connected in addition to the water supply tank (first water supply tank) 54 in the decontamination apparatus 1 used in the first embodiment. It has the structure which provided the tank (2nd water supply tank ) . The branch portion connected to the water supply hose 18 is connected to the first water supply tank 54 by one water supply hose (first water supply hose), and the second water supply tank is connected by another one water supply hose (second water supply hose). Connected to. An opening / closing valve (not shown) is provided in each of the first water supply hose and the second water supply hose. Other configurations of the decontamination apparatus used in the present embodiment are the same as those of the decontamination apparatus 1 used in the first embodiment.

  The decontamination method of this example will be described with reference to FIGS. 11A and 11B. The decontamination method of the present embodiment is a decontamination method in which two steps S19 and S20 are added to the decontamination method of the first embodiment. Other steps in the decontamination method of this example are the same as those of the decontamination method of Example 1.

  In the room 30 where the decontamination method of the present embodiment is performed, a plurality of pipes 48 are arranged between a resin plate-like member 47 installed on the ceiling 33 and the ceiling (building frame) 33.

  In the decontamination method of the present embodiment, steps S1 to S6 and S7 to S9 performed in the first embodiment are sequentially performed. The installation of the radiation shield in step S7 is performed when the determination in step S6 is “No”. After the step S9 is completed, it is determined whether access is possible (step S19). In step S19, it is determined whether the jet water flow 55 jetted from the jet nozzle 5 reaches the decontamination region of the plate member 34. When the spray water flow 55 reaches the decontamination region of the plate-like member 47 (for example, the lower surface of the plate-like member 47) as in the case where the radioactive substance is attached to the lower surface of the plate-like member 47, step S19. This determination is “accessible”, that is, “Yes”. At this time, after the step S10 is performed, the on-off valve provided on the first water supply hose is opened while the on-off valve provided on the second water supply hose is closed, and the water in the first water supply tank 54 is opened. Is guided to the injection nozzle 5 through the first water supply hose and the water supply hose 18 (step S11). A jet water flow 55 is jetted from the jet nozzle 5 toward the decontamination target area of the plate-like member 47. The jet water flow 55 decontaminates the lower surface, which is the decontamination region of the plate-like member 47.

  Further, when it is determined in step S19 that the jet water flow 55 ejected from the ejection nozzle 5 does not reach the decontamination region of the plate member 34, that is, when the determination in step S19 is “No”, Fine adjustment of the angle of the injection and injection nozzles is performed (step S20). The case where the determination in step S19 is “No” is, for example, a case where the radioactive substance 38 is attached to the outer surface of the second pipe 48 from the outside disposed between the plate-like member 47 and the ceiling 33. (See FIG. 12). In this case, fine adjustment of the angle of the injection nozzle 5 is performed, and a medicine containing a surfactant is injected from the medicine supply device into the water in the second water supply tank.

  Steps S10 and S11 are performed. In step S11, the open / close valve provided in the second water supply hose is opened in a state where the open / close valve provided in the first water supply hose is closed, and the water supply pump 10 is driven to activate the surface activity in the second water supply tank. The water into which the medicine containing the medicine is injected is guided to the injection nozzle 5 through the second water supply hose and the water supply hose 18. The water containing the surfactant becomes a foam-like jet flow 46 and is jetted from the jet nozzle 5 toward a region where the pipe 48 between the plate-like member 47 and the ceiling 33 is disposed. When the gas (air) in the room 30 is mixed into the water containing the surfactant ejected from the ejection nozzle 5, a foam-like jet flow 46 is formed.

  When the foam-like jet flow 46 jetted between the plate-like member 47 and the ceiling 33 reaches the periphery of the pipe 48 to which the radioactive substance 38 is attached, the water supply pump 10 is stopped, and the plate from the jet nozzle 5 is stopped. The injection of water containing a surfactant between the member 47 and the ceiling 33 is stopped. The foam-like jet stream 46 is attached as a foam-like projectile around the pipe 48 to which the radioactive substance 38 is attached. By maintaining the state in which the foamy propellant is in contact with the outer surface of the pipe 48 for a predetermined time, the radioactive substance 38 attached to the outer surface of the pipe 48 is washed by the foaming propellant that is in contact. Is done.

  After the predetermined time has elapsed, the on-off valve provided on the second water supply hose is closed, the on-off valve provided on the first water supply hose is opened, and the water supply pump 10 is driven. The water in the first water supply tank 54 is pressurized by the water supply pump 10 and injected from the injection nozzle 5 between the plate-like member 47 and the ceiling 33. Foam-like jets present between the plate member 47 and the ceiling 33 are washed away by the water jetted from the jet nozzle 5.

  Thereafter, steps S12 and S13 are performed. When the determination in step S13 is “Yes”, the steps S14, S15, S12, and S13 are repeated until the determination in step S13 becomes “Yes”, as in the first embodiment. In this repetition, in step S15, decontamination is performed by injecting water containing a surfactant supplied from the second water supply tank. When the determination in step S3 or S13 is “No” and the determination in step S16 is “Yes”, the decontamination work in one room is completed.

  Even if the determination in step S19 is “Yes” and the determination in step S13 is “Yes”, the processes in steps S14, S15, S12, and S13 are repeated until the determination in step S13 becomes “Yes”. . The decontamination in step S15 in this repetition is performed by injecting water (not including the surfactant) supplied from the first water supply tank 54.

  In the present embodiment, each effect produced in the first embodiment can be obtained. Furthermore, in this embodiment, since water containing a surfactant is jetted, it is possible to efficiently decontaminate the radioactive substance 38 present in the narrow part where the jet water flow 55 cannot reach. Furthermore, since the present Example can switch the injection from the injection nozzle 5 of the water in a 1st water supply tank, and the injection from the injection nozzle 5 of the water containing surfactant (chemical | medical agent) in a 2nd water supply tank. Therefore, appropriate decontamination can be performed according to the situation of the decontamination target area.

  You may add organic acids, such as an oxalic acid, instead of the chemical | medical agent containing surfactant in the water in a 2nd water supply tank. By spraying an aqueous solution of an organic acid such as oxalic acid from the spray nozzle 5, it is possible to improve the decontamination effect in a narrow portion where the spray water flow 55 does not reach.

  The decontamination method of Example 4, which is another preferred embodiment of the present invention, will be described with reference to FIGS. 13A, 13B and 14. FIG. As in the decontamination method of Example 3, the decontamination method of this example uses decontamination using the jet water stream 55 and water containing a drug (for example, a drug containing a surfactant and oxalic acid). Can be decontaminated. The decontamination method of this example is a decontamination method in which the process of step S17 is added to the decontamination method of Example 3.

  In the decontamination method of the present embodiment, the decontamination waste liquid recovery device 49 is used together with the decontamination device used in the third embodiment. The decontamination waste liquid collection device 49 includes a moving carriage 9C having a plurality of wheels, an elevating device 50, a suction device 53, and cameras 51 and 52. The elevating device 50 and the camera 52 are attached to the movable carriage 9C. A suction device 53 and a camera 51 are attached to the upper end of the lifting device 50.

  In the decontamination method of the present embodiment, steps S1 to S6, S8 to S9, and S19 performed in the first embodiment are sequentially performed. The installation of the radiation shield in step S7 is performed when the determination in step S6 is “No”. When the determination in step S19 is “No”, the process of step S20 is performed as in the third embodiment. After step S20 is completed, step S17 is performed. In the process of step S17 of this embodiment, a motor (not shown) provided on the movable carriage 9C is driven to move the decontamination waste liquid recovery device 49 in the horizontal direction, and the decontamination waste liquid recovery device 49 is a plate-like member. 47 is disposed in the vicinity of the decontamination region. Further, the lifting device 50 is driven, and the suction device 53 is raised. When the tip of the suction device 53 reaches the region between the plate-like member 47 and the ceiling 33, the lifting device 50 is stopped, and the lifting of the suction device 53 is stopped.

  Steps S10 and S11 are performed. In step S <b> 11, the water into which the chemical containing the surfactant in the second water supply tank is injected is guided to the injection nozzle 5 through the second water supply hose and the water supply hose 18. The water containing the surfactant becomes a foam-like jet flow 46 and is jetted from the jet nozzle 5 toward a region where the pipe 48 between the plate-like member 47 and the ceiling 33 is disposed. A region between the plate-like member 47 and the ceiling 33 is filled with the foam-like propellant (foamed surfactant) contained in the foam-like jet flow 46, and the pipe 48 having the radioactive substance 38 attached to the outer surface thereof is It is buried in a foam-like projectile. The radioactive material 38 adhering to the outer surface of the pipe 48 is cleaned by the foamed projectile in contact therewith. After a predetermined time has passed in this state, the foam-like propellant containing the radioactive material 38 present in the region between the plate-like member 47 and the ceiling 33 is sucked by the suction device 53 and removed from the region. Is done. The foam-like projectile sucked by the suction device 53 is discharged to an external tank (not shown) through a hose connected to the suction device 53. The sucked foam-like propellant may be collected in a collection tank provided in the decontamination waste liquid collection device 49.

  In step S11, after the foam-like propellant containing the radioactive substance 38 is collected, the water in the first water supply tank 54 is jetted from the jet nozzle 5 toward the region between the plate-like member 47 and the ceiling 33, The foam-like propellant remaining in the area is washed away by the jetted water.

  Thereafter, steps S12 and S13 are performed. When the determination in step S13 is “Yes”, the steps S14, S15, S12, and S13 are repeated until the determination in step S13 becomes “Yes”, as in the first embodiment. In this repetition, in step S15, decontamination is performed by injecting water containing a surfactant supplied from the second water supply tank. Also in the decontamination process of step S15, after the decontamination using the foam-like propellant is completed, the foam-like propellant including the radioactive substance 38 is collected using the decontamination waste liquid recovery device 49. When the determination in step S3 or S13 is “No” and the determination in step S16 is “Yes”, the decontamination work in one room is completed.

  When the determination in step S19 is “Yes”, in the process of step S11 after the process of step S10, the water in the first water supply tank 54 is changed from the injection nozzle 5 to the injection water flow 55 as in the first embodiment. Decontamination is performed.

  In the present embodiment, each effect produced in the third embodiment can be obtained. In the present embodiment, since the foam-like propellant containing the radioactive substance 38 can be collected using the decontamination waste liquid recovery device 49, the foam-like propellant containing the radioactive substance 38 is scattered in the room 30. Further, it is possible to reduce the time required for cleaning with water, which is performed after completion of decontamination in step S11 and the like.

DESCRIPTION OF SYMBOLS 1 ... Decontamination apparatus, 2 ... Injection nozzle moving apparatus , 4 ... Injection nozzle raising / lowering apparatus, 5 ... Injection nozzle, 8 ... Dose rate meter, 2B, 9, 9A, 9C ... Moving cart, 10 ... Water supply pump, 11 ... Removal Dyeing water supply device, 18 ... water supply hose, 20 ... camera monitor operation panel, 22 ... decontamination device operation panel, 23 ... computer, 25, 26 ... cable, 27, 40, 49 ... decontamination waste liquid recovery device, 28 ... removal Dye waste collection container, 29 ... collection hood, 30 ... room, 34, 47 ... plate member, 35, 48 ... pipe, 41, 53 ... suction device, 46 ... foam-like jet, 54 ... water supply tank, 55 ... Jet water flow.

Claims (11)

Pressure P _{b of} the water flow when the water flow pressurized by the pump and sprayed from the spray nozzle hits the decontamination target, from the spray nozzle to the decontamination position of the decontamination target to which the radioactive substance is attached The rate of decrease in the pressure of the water flow corresponding to the distance of the water, the rate of decrease in the amount of water in the water flow corresponding to the diameter of the injection nozzle of the injection nozzle , and the length of the hose connected to the pump to guide the water to the injection nozzle the first pressure P _a, which is determined based on the pressure loss of the hose which corresponds to, and sets the discharge pressure of the pump,
The water of the first pressure P _a discharged from the pump, leading to the ejection nozzle through the hose and sprayed from the ejection nozzle as the water flow,
The decontamination method, wherein the radioactive material attached to the decontamination object is removed by the jetted water stream. R ₁ the reduction rate of the pressure of the water flow, when k ₁ the reduction ratio of the water volume of the water flow, and the pressure loss of the hose and k _2, the first pressure P _a is the following formula ( The decontamination method of Claim 1 calculated | required by 1).
P _a = P _b × 1 / R ₁ × k ₁ × 1 / k ₂ (1) Decontamination of claim 1 for removing the radioactive material by the water while moving the ejection nozzle that injects the water of the first pressure P _a discharged from the pump at a first scanning speed Method. The removal of the radioactive material by the water while moving the ejection nozzle that injects the water of the first pressure P _a discharged from the pump at a first scanning rate,
After decontamination of the decontamination object by the water stream is conducted to measure the dose rate of the decontamination position, when the measured dose rate is higher than the set dose rate, the decontamination of the pressure P _b The first pressure at the time is changed to a second pressure higher than the first pressure, and the second pressure P _a is obtained by substituting the second pressure into P _b in the equation (1). Set the discharge pressure,
While spraying from the injection nozzle the water of the second pressure P _a discharged from the pump as the water stream moves at a slower second scanning rate than the injection nozzle said first scanning speed, the injection The decontamination method according to claim 2, wherein the radioactive substance adhering to the decontamination target is removed using the water stream that has been removed. The decontamination method according to claim 1 or 4, wherein the pressure _Pb is set to be equal to or less than an allowable pressure corresponding to a material of the decontamination target.   The decontamination method according to claim 5, wherein a material of the decontamination object is grasped by CAD data. Decontamination method according to claim 1 which is collected by collecting device the water of the water used in the decontamination of the decontamination object as waste.   When the position to which the radioactive substance of the decontamination object is attached is present at a position where the water stream injected from the injection nozzle does not reach, water containing either a surfactant or an organic acid is supplied from the injection nozzle. The spraying is performed, the surfactant or the organic acid is brought into contact with the radioactive substance attached to the surface of the decontamination target, and the radioactive substance attached to the surface of the decontamination target is removed. Decontamination method.   When the water containing the surfactant is sprayed on the object to be decontaminated arranged between the housing and the plate member of the building, the foamed surface activity existing between the housing and the plate member The decontamination method according to claim 8, wherein the agent is sucked by a recovery device.   The said injection nozzle attached to the raising / lowering apparatus provided in the moving trolley is moved by the said moving trolley and the said raising / lowering apparatus, and the said water flow is injected toward the said decontamination position of the said decontamination target object from this injection nozzle. The decontamination method according to claim 1.   The spray nozzle attached to a lifting device provided on a movable carriage is moved by the movable carriage and the lifting device, and the water stream containing either the surfactant or the organic acid is removed from the spray nozzle. The decontamination method according to claim 8, wherein the decontamination target is sprayed toward the decontamination position.

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