JP2016001138A - Decontamination method of radioactive substance and decontamination device thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a decontamination method of radioactive substance capable of improving decontamination efficiency on piping inner face and recovery efficiency of waste water even in a closed circumstance such as a piping.SOLUTION: The decontamination method is a method for removing radioactive substance from the inner face of a piping 7 by shooting pressured decontamination agent from a nozzle 1. The decontamination method includes the steps of: identifying the position of the radioactive substance on the inner face of the piping 7; setting a discharge pressure of the decontamination agent required for removing the radioactive substance, which is output from the nozzle 1 provided to a mobile unit 20a moving within the piping, according to the position of the radioactive substance; and shooting the decontamination reagent from the nozzle with the discharge pressure to remove the radioactive substance.

Description

  The present invention relates to a radioactive material decontamination method and a decontamination apparatus thereof, and more particularly to a radioactivity suitable for decontaminating the radioactivity on the surface of a structure by using a water stream for radioactive decontamination used in a nuclear power plant. The present invention relates to a substance decontamination method and a decontamination apparatus thereof.

  Normally, the equipment and piping of a nuclear power plant, as well as the tools used for maintenance inspection or repair of the nuclear power plant, must be disposed of after the end of their useful life. 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.

  This is because radioactive cobalt is attached to the reactor internal structure in the reactor pressure vessel of the nuclear power plant and piping connected to the reactor pressure vessel, and when a part of nuclear fuel is scattered. This is because radioactive materials such as cesium will adhere to floors and walls in buildings, grounds outside buildings, and buildings.

  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, it is also important not to diffuse radioactive material around it and to generate secondary radioactive waste other than the object to be decontaminated as much as possible. It becomes.

  The decontamination methods for removing radioactive substances are roughly classified into two types. The first decontamination method is mechanical decontamination that physically removes the radioactive substance attached to the surface of the object to be decontaminated, and the second decontamination method is a radioactive substance attached to the surface of the object to be decontaminated. Is chemical decontamination in which chemicals are chemically removed using chemicals or the like. In any method, the radioactive material is removed from the outer surface of the object to be decontaminated by cleaning the outer surface of the object to be decontaminated or peeling off a part of the surface layer of the object to be decontaminated.

  Further, the decontamination method by 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 substance 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, radioactive materials are scattered in the air along with the dust at the time of destruction, so facilities for cleaning the surrounding air are required.

  As an example of the wet method, there is a decontamination method described in Patent Document 1. In the decontamination method described in Patent Document 1, the decontamination object is immersed and fixed in water in a water tank, and the decontamination object is decontaminated by injecting high-pressure water from a nozzle. The cavitation bubbles generated in the generated water stream can be used for decontamination of the object to be decontaminated. Moreover, in the decontamination method described in Patent Document 1, after 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, using a decontamination agent requires a treatment facility for the decontamination agent.

  Further, as another example of the wet method, there is a method of cutting a structural member described in Patent Document 2. In the method for cutting a structural member described in Patent Document 2, a high pressure water flow (jet water flow) containing a cutting aid (for example, aluminum oxide powder) is jetted from a jet nozzle toward a cutting target. Is to cut. The cutting aid contained in the high-pressure water flow that cuts the object to be cut and is passed through the object is collected in a collection container that is disposed opposite the spray nozzle with the object to be cut interposed therebetween.

  Patent Document 3 describes a method for cutting a used control rod (cutting object) using a cutting aid. In this patent document 3, the used control rod is arrange | positioned in the area | region enclosed by the isolation film, and it prevents the cutting aid which cut | disconnected the used control rod from scattering to the circumference | surroundings.

  When applying the technology of the cutting method of the cutting object using these cutting aids to the decontamination of the decontamination object, the decontamination object is reduced by reducing the jet pressure of the jet water stream containing the cutting aid. Need to avoid damage.

  However, since the distance between the injection port of the injection nozzle that injects the jet water flow containing the cutting aid and the decontamination target is kept constant, the position and material of the decontamination target cannot be set in advance. May be difficult to decontaminate without damaging the object to be decontaminated. Furthermore, in these methods, a method for recovering the cutting aid is described, but a method for setting the injection condition of the jet water flow for the complicated decontamination target and a method for recovering the auxiliary have not been studied.

  On the other hand, in the decontamination method described in Patent Document 4, a jet water flow is jetted from the jet nozzle toward the decontamination target, and the decontamination target surface is decontaminated by the jet water flow jetted from the jet nozzle. ing. Further, carbon dioxide gas is blown into the water before being jetted from the jet nozzle to lower the pH of this water. That is, by blowing carbon dioxide into water, the water becomes acidic, and the acidified water is sprayed from the spray nozzle, and the decontamination target is decontaminated.

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

  When considering the decontamination work in a place where the radiation dose is high, the present inventors need the decontamination work remotely, and thus take advantage of the fact that the dust is relatively light and less scattered in the air. We focused on a wet decontamination method.

  Then, the present inventors, in the conventional decontamination method using a water stream, in order to improve the decontamination efficiency of radioactive substances attached to the decontamination target, A method of adding chemicals to the water and a method of mixing solids such as metals and ores as a decontamination aid into the jet water stream were studied.

  However, when a jet water flow containing cutting aid is used in a closed environment in the pipe, the decontamination efficiency is improved, but the cutting aid after use is at the bottom of the pipe in the portion where the pipe is horizontally arranged. Will be deposited. Therefore, it may be necessary to add a large amount of water to discharge the cutting aid.

  In addition, the water used for decontamination and the discharge of cutting aid has conventionally been sprayed from a spray nozzle that is close to the object to be decontaminated, so the water is mainly sucked in the vicinity of the spray nozzle. Recovery is performed by However, in the case of decontaminating a pipe in a vertically arranged part, the waste water flows downward, so that a method of sucking in the vicinity cannot be applied.

  The present invention has been made in view of the above points, and the object of the present invention is to improve the decontamination efficiency of the inner surface of the pipe and the recovery efficiency of waste water even in a closed environment such as a pipe. An object of the present invention is to provide a radioactive substance decontamination method and a decontamination apparatus therefor.

  In order to achieve the above object, the radioactive substance decontamination method of the present invention removes the radioactive substance present on the inner surface of the pipe by spraying a pressurized decontamination agent from a nozzle and removing the radioactive substance on the inner surface of the pipe. Specify the position of the radioactive substance, and according to the position of the radioactive substance, set the discharge pressure necessary to remove the radioactive substance from the nozzle installed in the moving device that moves in the pipe, The radioactive substance is removed by spraying the decontaminating agent from the nozzle at the discharge pressure.

  Further, in order to achieve the above object, the radioactive substance decontamination apparatus of the present invention is a moving apparatus that moves in the pipe to be decontaminated, and is installed in the moving apparatus, and decontamination of the radioactive substance on the inner surface of the pipe A nozzle for injecting a decontamination agent set to a discharge pressure and / or a moving speed necessary for removing the radioactive substance toward the decontamination position on the inner surface of the pipe when the moving device moves to a position; A decontamination agent tank connected to the nozzle via a first hose, and a moving device operation panel for operating the moving device are provided.

  According to the present invention, even in a closed environment such as piping, the decontamination efficiency of the inner surface of the piping and the recovery efficiency of waste water can be improved.

It is a figure which shows the outline | summary of the arrangement | positioning condition of the piping used as the decontamination object of the nuclear power plant to which the decontamination method and its decontamination apparatus of the present invention are applied. FIG. 2 is a perspective view of a pipe partially broken to show a state in which the moving device in Embodiment 1 of the radioactive substance decontamination apparatus of the present invention is inserted into the pipe shown in FIG. 1. It is a perspective view which shows the component apparatus of the decontamination apparatus outside the structure connected to the moving apparatus of the radioactive substance decontamination apparatus shown in FIG. It is a flowchart which shows the procedure of Example 1 of the decontamination method of the radioactive substance of this invention. It is a perspective view which shows the state which drills a high-order side through-hole and a low-order side through-hole in piping in Example 1 of the decontamination method of the radioactive substance of this invention. It is a perspective view which shows the other example of the state which drills a high-order side through-hole and a low-order side through-hole in piping in Example 1 of the decontamination method of the radioactive substance of this invention. It is a characteristic view which shows the relationship between the injection water pressure according to the moving speed of the nozzle in Example 1 of the decontamination method of the radioactive substance of this invention, and a removal rate. It is a flowchart which shows the procedure of Example 2 of the decontamination method of the radioactive substance of this invention. It is a flowchart which shows the procedure of Example 3 of the decontamination method of the radioactive substance of this invention. It is a characteristic view which shows the relationship between the injection water pressure according to the property of the deposit | attachment in piping in Example 3 of the decontamination method of the radioactive substance of this invention, and a removal rate.

  Hereinafter, the decontamination method and decontamination apparatus for radioactive materials of the present invention will be described based on the illustrated embodiments. In addition, in each Example, the same code | symbol is used for the same component.

  1 to 3 show a first embodiment of the radioactive substance decontamination apparatus of the present invention.

  As shown in FIG. 1, in a nuclear power plant, for example, a target pipe 7 is provided with a plurality of rooms 41 </ b> A and 41 </ b> B partitioned by a structure 10 in length and width.

  The radioactive substance decontamination apparatus of the present embodiment for decontaminating the radioactive substance present on the inner surface of the pipe 7 in which a plurality of such rooms 41A and 41B are laid vertically and horizontally is shown in FIGS. As described above, when the moving device 20a is moved to the decontamination position of the radioactive substance on the inner surface of the pipe 7 and moved to the decontamination position of the radioactive material on the inner surface of the pipe 7, the moving device 20a is moved. A nozzle 1 for injecting a decontamination agent set to a discharge pressure and / or a moving speed necessary for removing radioactive substances toward the dyeing position, and the nozzle 1 is connected via a first hose 3a. The decontaminant tank 4a is connected to the moving device 20a via the cable 17, and is composed of a moving device operation panel 23 for operating the moving device 20a.

  Note that (A), (B), (C), and (D) in FIG. 1 correspond to (A), (B), (C), and (D) in FIG. 2, and (A) in FIG. , (B), (C), and (D) are respectively connected to (A), (B), (C), and (D) of FIG.

  Further, the radioactive substance decontamination apparatus of the present embodiment is disposed on the downstream side of the radioactive substance decontamination position on the inner surface of the pipe 7, for example, a water stop material made of foaming urethane or a resin curing material. 21, a recovery nozzle 20 b installed in the water-stopping material 21 (a pipe comes out of the water-stopping material 21), and a waste water of the decontaminating agent staying in the water-stopping material 21. The waste decontamination agent recovery comprising the suction pump 22 that is collected from the second hose 3b and the waste decontamination tank 4b that guides and stores the waste water of the decontamination agent from the suction pump 22 via the third hose 3c. And a device.

  In the middle of the first hose 3a described above, a feed water pump 2a is installed that pressurizes the decontaminant from the decontaminant tank 4a to a discharge pressure necessary for removing radioactive substances and supplies it to the nozzle 1. ing.

  On the other hand, in the decontamination agent tank 4a, a liquid level meter 11a for detecting the liquid level in the decontamination agent tank 4a, and when the liquid level meter 11a detects that the liquid level in the decontamination agent tank 4a is lowered, it is opened. A water supply switch 13 for performing the operation and a replenishing device 12 for replenishing the decontamination agent to the decontamination tank 4a when the water supply switch 13 is opened are installed. The waste decontaminant tank 4b is provided with a liquid level meter 11b that detects the fullness of the waste decontaminant, and is provided with a dose rate meter 16b that can detect an increase in dose rate even when the liquid level is low. it can.

  Moreover, the water stop material 21 mentioned above is connected to the water stop material tank 4c via the 4th hose 3d, and the water stop material supply pump 2b is installed in the middle of the 4th hose 3d.

  In addition, the moving device 20a includes a dose rate meter 16a that measures the dose rate in the target range in the pipe 7 after removing the radioactive material in the target range in the pipe 7, and the dose rate meter 16a is connected to the cable 17 The radiation measurement board 24 is connected to the radiation measurement board 24, and the radiation measurement board 24 displays the dose rate measured by the dose rate meter 16a and / or compares the measured dose rate with a preset target dose rate. (To be described later).

  Further, a switching valve 14 is installed in the middle of the third hose 3c, and a sampling container 15 and a nuclear fuel recovery container 5 are connected to the switching valve 14 and the decontamination agent sucked by the suction pump 22 is connected. The waste water of the decontaminant sucked by the suction pump 22 is switched if the nuclear waste material is contained in the waste water of the decontaminant. The valve 14 is switched to recover the nuclear fuel recovery container 5. The nuclear fuel recovery container 5 is stored in the shielding container 8 and includes a liquid level meter 11c and a dose rate meter 16c. The liquid level meter 11c and the dose rate meter 16c define the amount of waste water and the waste water dose of the decontamination agent. Excessive quantity can be detected.

  Next, Example 1 of the radioactive substance decontamination method of the present invention will be described with reference to FIGS.

  FIG. 4 shows the operation procedure of STEP (hereinafter abbreviated as S) 1 to S13 in the method for decontaminating radioactive materials of the present embodiment, and the apparatus configuration when decontaminating the inner surface of the pipe 7 (FIG. 4). The outline will be described below together with 1 to 3).

First, when starting the decontamination work in the pipe 7, a range (nozzle movement range) in which the decontamination work is performed is set in S1. For example, as shown in FIG. 1, since the target pipe 7 has a plurality of rooms 41A and 41B laid vertically and horizontally, construction records and related drawings stored in S2, a drawing during operation change, a camera image Based on the above, the route and length of the pipe 7 are grasped. In S3, the dose rate (A ₁ ) of the work place is measured by a dose rate meter or the moving device 20a from the outside of the pipe 7 in order to grasp the situation of the work place (the amount of radiation dose or the height of the radiation dose). The dose rate is measured by the dose rate meter removed from the above, and the location (position) where the radioactive substance is present roughly in the pipe 7 is specified.

  By using a gamma camera to visualize the radiation by superimposing the output value depending on the radiation dose from the radiation detection element on the camera image, or by exposing the photographic film or the fluorescent screen with the radiation, the pipe 7 is roughly arranged. It is also possible to specify where (position) the radioactive substance exists.

  Then, on the route of the pipe 7 including the decontamination range, a part having a dose rate as low as possible and a pipe 7 in the vicinity of the closing valve 40 (see FIG. 1) are selected, and the moving device 20a and the stop are connected to the selected pipe 7. The high-side through-hole 6a and the low-side through-hole 6b for inserting the water material 21 are drilled (S4). As shown in FIG. 2, the water blocking material 21 is injected from the lower side through hole 6b into the pipe 7 near the lower side through hole 6b at S5 (S5), and the moving device 20a is moved from the higher side through hole 6a at S6. It inserts in the piping 7 (S6).

  Since the waste water of the decontaminating agent (including water or a mixed liquid of water and organic acid) flows to the downstream side of the path of the pipe 7, as described above, A waste water recovery nozzle 20b is installed in the pipe 7 through the lower side through-hole 6b.

  Further, when cutting the high-side through-hole 6a and the low-side through-hole 6b, there is a concern that a part of the radioactive substance may be scattered to the outside air accompanying the gas staying in the pipe 7. As shown in FIG. 5, the curing container 30 is fixed to the outer surface of the pipe 7 with a grip belt 37 or the like so that it can be shut off from the outside air, thereby preventing a part of the radioactive material from scattering to the outside air. Then, the hole saw 32 connected to the rotary motor 31 is fixed in the curing container 30 and drilled into the pipe 7 in the curing container 30 to form the high-order through hole 6a and the low-order through hole 6b. At this time, the radioactive material scattered from the inside of the pipe 7 is sucked by the exhaust pump 34 and guided to the collecting material 35 made of a filter or activated carbon, cleaned by the collecting material 35 and returned to the curing container 30. .

  In addition, when a pressure fluctuation in the curing container 30 is expected due to the ejection of gas or the like from the pipe 7, as shown in FIG. 6, the gas cylinder 36 is used, the exhaust amount by the exhaust pump 34 and the supply from the gas cylinder 36. This can be dealt with by adjusting the balance of the air volume with the pressure gauge 33.

  In S <b> 7, after moving the moving device 20 a to the decontamination position in the pipe 7, the decontamination agent is sprayed from the nozzle 1 to the decontamination position in the pipe 7.

Here, as shown in FIG. 7, the injection condition for obtaining a predetermined removal rate DF (DF> A ₁ / A ₀ ) is the discharge pressure P _M (the movement speed of the nozzle 1 is different for each movement speed of the nozzle 1. Set to medium speed M) or P _L (when the movement speed of the nozzle 1 is low speed L) (S8). After decontamination of the target range in S9, the dose rate (A ₂ ) of the decontamination range in the pipe 7 is measured by the dose rate meter 16a in S10. In S11, the dose rate (A ₂ ) measured by the dose rate meter 16a is compared with the preset target dose rate (A ₀ ) by the radiation measurement panel 24, and the dose rate (A ₂ ) is the target dose rate. If not lower than (A ₀ ), in S12, the moving speed and discharge pressure of the nozzle 1 are changed on the moving device operation panel 23 so that the removal rate DF increases from the relationship of FIG. Dyeing is carried out. If the dose rate (A ₂ ) falls below the target dose rate (A ₀ ), the completion of the work is determined in S13, and the work is completed or another decontamination range is set.

  Thus, in the present embodiment, the moving device 20a is provided with the nozzle 1 for injecting the decontamination agent pressurized by the feed water pump 2a connected from the decontamination agent tank 4a via the first hose 3a. The radioactive substance adhering to the inner surface of the pipe 7 can be removed by spraying the decontaminating agent with the nozzle 1. The radiation measurement panel 24 and the moving device operation panel 23 are connected by a cable 17 and can be scanned remotely from the outside of the structure 10. Further, the decontamination waste water staying in the water stop material 21 is recovered from the recovery nozzle 20b by the suction pump 22 and stored in the waste decontamination tank 4b.

  Furthermore, since the decontaminating agent is consumed when the nozzle 1 is continuously ejected, the liquid level meter 11a detects that the liquid level in the decontaminating agent tank 4a is lowered, and the water supply switch 13 is opened to supply the replenishing device. From 12, the decontamination agent is supplied to the decontamination tank 4 a. Similarly, the waste decontamination agent in the waste decontamination tank 4b is similarly detected by the liquid level meter 11b, and is provided with a dose rate meter 16b, and an increase in dose rate can be detected even when the liquid level is low.

  Therefore, according to the present embodiment, when removing the radioactive material adhering to the inner surface of the pipe 7 by using the spray of the decontaminating agent, only an appropriate range is selected and the end portion and the device insertion portion are sealed. Thus, it is possible to suppress the scattering of radioactive substances inside the pipe 7 and collect the entire amount of waste water. Moreover, the usage-amount of a decontaminating agent can be reduced by setting to the discharge pressure according to the adhesion state inside the piping 7, and the amount of secondary waste can be suppressed.

  Therefore, according to the present Example, even if it is a blocky environment like piping, the effect which can improve the decontamination efficiency of the inner surface of piping, and the recovery efficiency of wastewater can be acquired.

  FIG. 8 shows Example 2 of the radioactive substance decontamination method of the present invention. The embodiment shown in the figure is obtained by adding the work procedure of S14 to S19 to the work procedure of the first embodiment shown in FIG. 4, and is a work procedure when nuclear fuel material is contained in the decontamination wastewater. is there.

  Steps S1 to S9 in FIG. 8 are the same as the work procedure of the first embodiment shown in FIG. 4. After decontamination is performed in S9 in FIG. 8, injection is temporarily stopped in S14, and a part of the waste water is recovered. To do. In this recovery, waste water is sucked by the suction pump 22 shown in FIG. 3 and pumped to the sampling container 15 by the switching valve 14. After sampling, the nuclides, chemical components, and concentrations in the wastewater are quantitatively analyzed in S15. In S16, when the regulated substances such as nuclear fuel substances are contained in the wastewater, the wastewater recovery system is switched by the switching valve 14 in S17 and connected to the nuclear fuel collection container 5, and when the regulated substances such as nuclear fuel substances are not contained, Decontamination is resumed at S18.

  Specifically, the waste water recovery system is connected to the nuclear fuel container 5 stored in the shielding container 8 by the switching valve 14 shown in FIG. The nuclear fuel recovery container 5 is provided with a liquid level meter 11c and a dose rate meter 16c, and the liquid level meter 11c and the dose rate meter 16c can detect the amount of waste water of the decontaminating agent and an excess of the prescribed amount of waste water dose. it can. In S19, the nuclear fuel material content in the wastewater recovered in the nuclear fuel recovery container 5 is measured, and the decontamination work is completed.

  By adopting such a present embodiment, it is possible to obtain the same effect as in the first embodiment, and of course, when the nuclear fuel material is contained in the decontamination wastewater, the decontamination wastewater and the nuclear fuel material are separated. It can be collected separately.

  FIG. 9 shows Example 3 of the radioactive substance decontamination method of the present invention. The present embodiment shown in the figure is an operation procedure in which S20 for adjusting the discharge pressure of the nozzle 1 is added when the nuclear fuel material is contained in the decontamination wastewater of the embodiment 2 shown in FIG. .

  Usually, when the nuclear fuel material is contained in the wastewater, there is a high possibility that it is mixed in the pipe 7 in the form of particles. At that time, as shown in FIG. 10, since the particulate deposits can be removed at a pressure lower than the discharge pressure for decontaminating the oxide film adhering in the pipe 7, in this embodiment, the discharge of the nozzle 1 is performed. After adjusting the pressure, decontamination is resumed in S18.

  By adopting such a present embodiment, the same effect as in the second embodiment can be obtained, and the amount of decontaminating agent can be reduced by lowering the discharge pressure in S20, and the amount of secondary wastewater. Can be suppressed.

  In addition, this invention is not limited to an above-described Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

  The present invention can be applied to a radioactive material decontamination work attached to the inner surfaces of liquid pipes, gas pipes, cable ducts and the like used in nuclear power plants.

  DESCRIPTION OF SYMBOLS 1 ... Nozzle, 2a ... Water supply pump, 2b ... Water stop material supply pump, 3a ... 1st hose, 3b ... 2nd hose, 3c ... 3rd hose, 3d ... 4th hose, 4a ... Decontamination agent Tank, 4b ... Waste decontamination tank, 4c ... Water stop tank, 5 ... Nuclear fuel recovery container, 6a ... Higher side through hole, 6b ... Lower side through hole, 7 ... Piping, 8 ... Shielding container, 10 ... Structure, 11a, 11b, 11c ... liquid level meter, 12 ... replenishing device, 13 ... water supply switch, 14 ... switching valve, 15 ... sampling container, 16a, 16b, 16c ... dose rate meter, 17 ... cable, 20a ... moving device, 20b DESCRIPTION OF SYMBOLS ... Recovery nozzle, 21 ... Water stop material, 22 ... Suction pump, 23 ... Moving device operation panel, 24 ... Radiation measurement board, 30 ... Curing container, 31 ... Rotary motor, 32 ... Hole saw, 33 ... Pressure gauge, 34 ... Exhaust Pump, 35 ... Collection , 36 ... gas cylinder, 37 ... grip belt, 40 ... closure valve, 41A, 41B ... room.

Claims (15)

When removing the radioactive material existing on the inner surface of the pipe by spraying the pressurized decontamination agent from the nozzle,
Discharge necessary for identifying the position of the radioactive substance on the inner surface of the pipe and removing the radioactive substance from the nozzle installed in a moving device that moves in the pipe according to the position of the radioactive substance A method for decontaminating radioactive material, comprising setting a pressure and ejecting the decontaminating agent from the nozzle at the discharge pressure to remove the radioactive material. In the decontamination method of the radioactive substance of Claim 1,
The moving speed of the nozzle is set according to the position of the radioactive substance in the pipe, and the radioactive substance is removed by spraying a decontamination agent from the nozzle at the moving speed and / or discharge pressure of the nozzle. A method for decontaminating a radioactive material. In the decontamination method of the radioactive substance of Claim 1 or 2,
The decontamination method of the radioactive substance includes a step of setting a decontamination range of the pipe, a step of measuring a radiation dose rate at a decontamination work place from outside the pipe and specifying a position of the radioactive substance, and the decontamination range. A pipe portion with a low radiation dose rate is selected on the route of the pipe including the high-side through hole and the low-side through hole for inserting the moving device and the water stop material into the selected pipe portion. A step of drilling, a step of injecting the water blocking material into the pipe from the low side through hole, a step of inserting the moving device into the pipe from the high side through hole, After moving to the decontamination position in the pipe, the discharge pressure of the nozzle is set for each moving speed of the nozzle installed in the moving device, and the decontamination in the pipe from the nozzle with the set discharge pressure. Spray decontaminant at the position And after decontamination of the target area in the pipe, measuring the radiation dose rate of the target area in the pipe with a dose rate meter, and in the pipe measured in the dose rate meter A step of comparing the radiation dose rate of the target range with a preset target radiation dose rate, and when the measured radiation dose rate is not less than the target radiation dose rate in the comparison, the nozzle Changing the moving speed and / or discharge pressure of the nozzle and returning to the step of injecting the decontaminating agent from the nozzle to the decontamination position in the pipe again, and performing the decontamination, and the radiation measured in the comparison A method for decontaminating radioactive material, comprising the step of ending work or setting another decontamination range when the dose rate falls below the target radiation dose rate. In the decontamination method of the radioactive substance of Claim 3,
After decontamination of the target area in the pipe, the step of temporarily stopping the spray of the decontaminating agent from the nozzle and collecting the waste water of the decontaminating agent, and sampling the recovered waste water of the decontaminating agent A step of pumping and analyzing in a container; a step of determining whether or not nuclear fuel material is contained in the waste water of the decontamination agent as a result of the analysis; and a result of the determination in the waste water of the decontamination agent If nuclear fuel material is included, connecting the decontamination waste water to the nuclear fuel recovery container; after connecting the decontamination waste water to the nuclear fuel recovery container, or as a result of the determination, The method further comprises a step of returning to the step of restarting decontamination and measuring the radiation dose rate of the target area in the pipe with a dose rate meter when the nuclear fuel material is not contained in the waste water of the decontamination agent. Of radioactive material characterized by Dyeing method. In the decontamination method of the radioactive substance of Claim 4,
After the waste water of the decontaminating agent is connected to the nuclear fuel recovery container, the method includes a step of changing the discharge pressure of the nozzle, and after changing the discharge pressure of the nozzle, the decontamination is resumed and the target in the pipe A decontamination method for radioactive substances, wherein the method returns to the step of measuring the radiation dose rate in the range with a dose rate meter. In the decontamination method of the radioactive substance of any one of Claims 3 thru | or 5,
The step of drilling the high-order side through-hole and the low-order side through-hole for inserting the moving device and the water-stopping material into the pipe part fixes a curing container that is blocked from outside air on the outer surface of the pipe, A decontamination method for a radioactive substance, wherein a hole saw is connected to a rotary motor in the curing container.   A moving device that moves in the pipe to be decontaminated, and the radioactive device that is installed in the moving device and moves toward the decontamination position of the inner surface of the pipe when the moving device moves to the decontamination position of the radioactive substance on the inner surface of the pipe. A nozzle for injecting a decontamination agent set to a discharge pressure and / or a moving speed necessary for removing the substance, a decontamination tank connected to the nozzle via a first hose, and the moving device A decontamination apparatus for radioactive material, comprising a moving device operation panel for operating the device. The radioactive substance decontamination apparatus according to claim 7,
The radioactive substance decontamination apparatus includes a water stop material disposed on the downstream side of the radioactive substance decontamination position on the inner surface of the pipe, a recovery nozzle installed in the water stop material, and the water stop material. A suction pump that collects the remaining waste water of the decontamination agent from the recovery nozzle via the second hose, and guides and stores the waste water of the decontamination agent from the suction pump via the third hose. A decontamination apparatus for a radioactive material, further comprising a waste decontamination agent recovery device comprising a waste decontamination agent tank. The radioactive substance decontamination apparatus according to claim 7 or 8,
In the middle of the first hose, a water supply pump is installed to press the decontamination agent from the decontamination agent tank to a discharge pressure required to remove the radioactive substance and supply the nozzle to the nozzle. A decontamination apparatus for radioactive materials characterized by the above. The radioactive substance decontamination apparatus according to claim 9,
The decontamination tank includes a liquid level meter that detects a liquid level in the decontamination tank, and a water supply switch that opens when the liquid level gauge detects that the liquid level in the decontamination tank has decreased. And a replenishing device for replenishing the decontamination agent to the decontamination agent when the water supply switch is opened. The radioactive substance decontamination apparatus according to any one of claims 7 to 10,
The water-stopping material is connected to a water-stopping material tank through a fourth hose, and a water-stopping material supply pump is installed in the middle of the fourth hose. apparatus. The radioactive substance decontamination device according to any one of claims 7 to 11,
The radioactive substance decontamination apparatus comprising a dose rate meter that measures a dose rate of a target range in the pipe after the radioactive substance in the target range in the pipe is removed. The radioactive substance decontamination apparatus according to claim 12,
The dose rate meter is connected to a radiation measurement board via a cable, and the radiation measurement board displays the dose rate measured by the dose rate meter and / or compares the measured dose rate with a target dose rate. A decontamination device for radioactive materials characterized by The radioactive substance decontamination apparatus according to any one of claims 7 to 13,
A switching valve is installed in the middle of the third hose, and a sampling container and a nuclear fuel recovery container are connected to the switching valve, respectively, and the decontaminant waste water sucked by the suction pump is switched. If the nuclear fuel material is contained in the waste water of the decontamination agent, the waste water of the decontamination agent sucked by the suction pump is changed over by switching the valve. The radioactive material decontamination apparatus collects in the nuclear fuel recovery container. The radioactive substance decontamination device according to claim 14,
The nuclear fuel recovery container is housed in a shielding container and is equipped with a liquid level meter and a dose rate meter, and the liquid level meter and dose rate meter detect the excess amount of the decontamination waste water and the waste water dose. A decontamination apparatus for radioactive substances characterized by

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