JP6491814B2 - Method for preventing expansion of pollution at power plant dismantling and internal investigation method at power plant dismantling - Google Patents

Description

  The present invention relates to a method for preventing the spread of contamination in a power plant, a shielding method, and a method for investigating the inside of a power plant.

  There are various types of power plants. For example, in a nuclear power plant, water is boiled with a large amount of heat generated by the nuclear fuel splitting reaction in a reactor pressure vessel, and steam is produced. The power is generated by rotating the generator by spraying it on the turbine connected to the generator.

  Nuclear power plants may be dismantled from nuclear reactors due to aging or natural disasters. Patent Document 1 describes a reactor building dismantling system that covers a reactor building with a protective building that is divided into three parts in the vertical direction in the reactor building dismantling system. Furthermore, an access gantry and an overhead traveling transport crane provided on the ceiling surface are provided inside the protective building. It is described that the access gantry is provided with a radiation shielding area surrounded by a shielding member that shields radiation to dismantle the reactor building. In Patent Document 1, when dismantling a nuclear reactor, the reactor building is covered with a protective building to prevent the radioactive material from being scattered outside.

JP 2013-29334 A

  In the reactor building dismantling system described above, by installing a protective building, when the reactor building is dismantled, radioactive reinforced concrete frames and radioactive materials adhering to the reactor building frame are scattered to the outside of the protective building. Is preventing. However, there is room for further improvement in the protection building, where radioactive dust generated during dismantling may adhere to the walls and ceiling of the protection building and increase the radiation dose in the protection building.

  Therefore, the problem to be solved by the present invention is to prevent dust scattering at the time of dismantling the nuclear reactor plant.

In order to solve the above-described problems, the present invention provides a gel or a viscous gel through a through-hole provided in a shield plug into a space surrounded by a reactor well, a shield plug, and a PCV head provided in a reactor building. A foam material is injected, a part of the space inside the reactor building is filled with gel or foam material, and then the shield plug is removed and carried out to the reactor building outdoor portion.

  ADVANTAGE OF THE INVENTION According to this invention, dust scattering prevention at the time of a nuclear reactor plant dismantling becomes possible.

It is a figure explaining the preparation step for performing the operation | work in Example 1. FIG. It is a figure explaining the step which installs a seal box apparatus in a shield plug. It is a figure explaining the step which provides a hole in a shield plug using a punching device. It is a figure explaining the step which provides a hole in the outer periphery of a shield plug using a punching device. It is a figure explaining the step which inject | pours a 1st gel to the vicinity of a well seal bellows. It is a figure explaining the step which injects the 2nd gel to a reactor well part. It is a figure explaining the step which provides a hole in PCV head using a punching device. It is a figure explaining the step which inject | pours a 3rd gel into a PCV head. It is a figure explaining the step which provides a hole in an RPV head using a punching device. It is a figure explaining the step which installs a sheet | seat in a RPV head. It is a figure explaining the step which inject | pours a 4th gel to the sheet | seat in a RPV head. It is a figure explaining the mode of a nuclear reactor plant after a 4th gel is inject | poured into the sheet | seat in a RPV head. It is a figure explaining the removal step of a shield plug. It is a figure explaining the mode of a nuclear reactor plant after removal of a shield plug. It is a figure explaining the removal step of the various gel of Example 1, and a nuclear reactor structure. FIG. 3 is a flowchart of work steps according to the first embodiment. It is a figure explaining the step which provides a several hole in a shield plug using the punching apparatus in Example 2. FIG. It is a figure explaining the step which installs the decontamination apparatus and decontamination water collection | recovery apparatus in Example 2. FIG. It is a figure explaining the step which decontaminates the inside of a well using the decontamination apparatus and decontamination water collection | recovery apparatus in Example 2. FIG. It is a figure explaining the step which installs the perforation apparatus in Example 2. FIG. FIG. 10 is a diagram illustrating a step of providing a plurality of holes in a PCV head in Example 2. It is a figure explaining the step which decontaminates the inside of a PCV head using the decontamination apparatus and decontamination water collection | recovery apparatus in Example 2. FIG. It is a figure explaining the step which installs the perforation apparatus in Example 2. FIG. It is a figure explaining the detailed structure of the boring apparatus in Example 3. FIG. It is a figure explaining the step which implements the investigation inside a nuclear reactor using the boring apparatus in Example 3. FIG. It is a figure explaining the detail of guide pipe connection in Example 3. FIG. FIG. 10 is a diagram illustrating detailed steps for inserting a guide pipe into a sheet in an RPV head in Example 3.

  Embodiments of the present invention will be described below with reference to the drawings.

  Example 1 is demonstrated below using the example applied to the boiling water nuclear power plant.

  First, a schematic structure of a boiling water nuclear power plant to which this embodiment is applied will be described with reference to FIG. The application target of the present invention is not limited to a boiling water nuclear plant, but can be applied to a pressurized water nuclear plant, a thermal power plant, and the like.

  The boiling water nuclear power plant 1 includes a nuclear reactor 2 and a reactor containment vessel (hereinafter referred to as PCV 3). The PCV 3 is installed in the reactor building 4 and is sealed with an upper lid (PCV head 5) attached to the upper end portion. A shield plug 6, which is a radiation shielding body divided into a plurality of parts, is disposed immediately above the upper lid of the PCV, and these shield plugs 6 are installed on the operation floor of the reactor building (hereinafter referred to as operation floor 7).

  The nuclear reactor includes a reactor pressure vessel (hereinafter referred to as RPV 9) configured with an upper lid (RPV head 8) attached thereto, a core 10 loaded with a plurality of fuel assemblies containing nuclear fuel material, a steam dryer 11 and a gas dryer. A water separator 12 is provided. The core, the steam / water separator and the steam dryer are disposed in the RPV, and the steam dryer 11 is disposed above the steam / water separator 12.

  The RPV is installed on a cylindrical pedestal 14 provided on a concrete mat 13 provided at the bottom of the PCV. A cylindrical γ-ray shield 15 is installed at the upper end of the pedestal and surrounds the RPV.

  The reactor building has a dryer / separator pool (hereinafter abbreviated as DSP 16) and a spent fuel storage pool (hereinafter abbreviated as SFP 17) for temporarily storing spent fuel so as to sandwich the reactor well 20 therebetween. Is provided. The DSP is used as a place for temporarily placing in-furnace structures such as steam dryers and steam separators during periodic inspections. Further, a heat insulating material 21 is provided on the upper portion of the RPV head 8.

  An outline of the form of fuel debris when core melting occurs in a boiling water nuclear power plant is shown. When the function of the cooling facility is lost and cooling water is not injected into the RPV, the fuel pellets in the fuel assembly, the cladding tube, and the like are melted by the decay heat of the nuclear fuel. In this case, the molten nuclear fuel is presumed to be present at the position 18 where it originally existed, at the bottom of the RPV furnace, or on the concrete mat 19 that is the bottom of the PCV.

  As shown in FIG. 1, first, the first house 51 is installed on the upper part of the nuclear reactor 2. An upper opening / closing type shielding plate 52 and a lower opening / closing type shielding plate 53 are provided in the upper and lower portions of the first house. Next, a second house 54 having the same structure as the first house 51 is installed. Furthermore, an equipment carry-in / out box 55 that can move on the upper part of the core and the DSP and store various equipment and structures is installed above the first house 51 and the second house 54. In addition, a seal box device 56 is provided in advance in the equipment carry-in / out box 55. Inside the first house 51, the second house 54, and the equipment loading / unloading box 55, a crane device 57 is provided so that various devices can be moved remotely. In addition, a cable for operating various devices remotely and a power cable for moving various devices are bundled together to have a seal cable 58 connected in a sealed state to the device carry-in / out box 55.

  The work steps in this example are shown in FIG. In this embodiment, the work is performed according to the steps shown in FIG.

  As shown in FIG. 2, a first house 51, a second house 54, and an equipment carry-in / out box 55, which are work houses, are installed, and the seal box device 56 is moved from the equipment carry-in / out box 55 through the first house 51. Then, it is installed in the lower stage of the shield plug 6 (step 1). The upper and middle stages of the shield plug have been removed in advance. The shield box device is provided with a punching device 59 for providing a hole in a shield plug or the like, a decontamination device 60 for decontaminating a contaminated portion, and an injection device (not shown) for injecting various gels.

  As shown in FIG. 3, the 1st hole 61 is provided in the lower stage of the shield plug 6 with the punching apparatus with which the shield box apparatus was equipped. This hole is once closed with a closing plug, and then a second hole 62 is similarly provided on the outer periphery of the shield plug by a punching device as shown in FIG. 4 (step 2). Subsequently, the reactor well, which is the first space surrounded by the shield plug 6, the PCV head 5, and the well seal bellows 65, is decontaminated (step 3).

  As shown in FIG. 5, the injection device 63 injects the first seal 64 so as to cover the well seal bellows 65 (step 4). The first gel 64 can prevent dust from leaking through the penetrating portion of the well seal bellows. Subsequently, as shown in FIG. 6, the second gel 66 is injected into the entire reactor well (step 5). Details of the various gels will be described later.

  By the work so far, the space surrounded by the reactor well, the shield plug, and the PCV head is filled with the first gel and the second gel. By filling this space with the first gel and the second gel, dust can be prevented from being scattered in the subsequent work.

  Next, as shown in FIG. 7, a hole is provided in the PCV head using a punching device (step 6). Thereafter, the inner surface of the PCV head and the outer surface of the RPV head are decontaminated using a decontamination apparatus (step 7). As shown in FIG. 8, the third gel 68 is injected into the space surrounded by the PCV head, the RPV head, and the fuel change bellows 67 using an injection device (step 8).

  Thereafter, as shown in FIG. 9, a hole is provided in the RPV using a punching device (step 9). Then, the inner surface of the RPV head and, if necessary, the steam dryer is decontaminated using a decontamination apparatus (step 10). As shown in FIG. 10, a sheet 69 is installed in the RPV head (step 11). The fourth gel 70 is injected into the seat 69 installed as shown in FIG. 11 (step 12). The state of the nuclear reactor plant after the fourth gel 70 is injected into the sheet is shown in FIG.

  Next, as shown in FIG. 13, the shield plug is divided into a plurality of parts using a cutting device (not shown) separately installed, and each is carried out to the outside. The state of the nuclear reactor plant after the shield plug is carried out is shown in FIG. Even if the shield plug is removed, since the space of the reactor well is filled with the first gel and the second gel, it is possible to prevent dust from being scattered when taking out various members. Thereafter, as shown in FIG. 15, various nuclear reactor structural members are removed (step 13). The first gel 64 and the second gel 66 injected into the first space surrounded by the shield plug 6, the PCV head 5, and the well seal bellows 65 are taken out. Next, the PCV head 5 is removed. Further, the third gel 68 injected into the second space surrounded by the PCV head 5, the RPV head 8 and the fuel change bellows 67 is taken out, and the RPV head 8 is carried out. Finally, the fourth gel 70 wrapped in the sheet is removed.

  As in this embodiment, the first space, the second space, and the third space surrounded by the nuclear reactor structure are sealed with various gels, thereby preventing dust scattering in each operation, The PCV head 5 and RPV head 8 can be taken out.

  Next, the filled gel used in this example will be described. The first gel is provided for the purpose of suppressing dust leakage from the well seal bellows. An example of the material is a replica material that is cured by two-component mixing. There are low-viscosity (fluid type) and high-viscosity (thixo-type), but low-viscosity ones are easy to flow.

  As the second gel, a material having a shielding function is used. For example, a nanocomposite type hydrogel (NC gel) can be mentioned. Since 90% is composed of moisture, a shielding effect by water can be expected. Moreover, you may make it give a shielding effect by adding a silicon-type material inside a gel material. Here, the first gel and the second gel may be the same. That is, the entire space of the reactor well may be filled with the first gel or may be filled with the second gel. In the case of the first gel, the cured gel can be divided and taken out when taking out. When filled with the second gel, it is in a gel state and can be taken out with a suction device. Moreover, the 3rd gel and the 4th gel can use the same thing as the 1st gel and the 2nd gel. As a result, the effect of each material can be expected, such as the effect of shielding radiation from inside the reactor. The second gel and the third gel may use a foam material (urethane foam or the like) in consideration of exclusion when accessing a tool for removing the bolts of the PCV head and the RPV head. The first gel, the second gel, the third gel, and the fourth gel of this embodiment may be poured into a sheet and packed in a sheet. When a sheet is used, the work can be easily performed because it can be collected together with the sheet. Furthermore, instead of the gel used in the present embodiment, a space may be replaced by inserting a bag (sheet) and inflating it (not shown). In this case, it is possible to prevent dust from being scattered while realizing weight reduction.

  A second embodiment will be described below with reference to FIGS. In the second embodiment, when holes are provided in the shield plug 6 or the like, a plurality of holes are provided, and the decontamination is performed by the decontamination apparatus 60 and the decontamination liquid recovery apparatus 100 using the holes. It is different from the embodiment. Description of the same parts as those in the first embodiment is omitted.

  As shown in FIG. 17, a plurality of holes are provided after the drilling device 59 is installed in the lower stage of the shield plug 6. The portion provided with the hole is closed with a plug or the like until the next operation is performed as necessary.

  As shown in FIG. 18, the decontamination device 60 is installed in the central hole provided in the lower stage of the shield plug 6. The decontamination liquid recovery apparatus 100 is installed in the outer peripheral hole provided in the lower stage of the shield plug 6. Then, as shown in FIG. 19, the inside of the reactor well 20 which is 1st space is decontaminated using the decontamination apparatus 60 and the decontamination liquid collection | recovery apparatus 100. FIG. In the decontamination liquid recovery apparatus 100, the decontamination liquid sprayed from the decontamination apparatus 60 is recovered. By collecting the decontamination liquid collected in the reactor well 20 using the decontamination liquid recovery apparatus 100, it is possible to prevent the spread of contamination to other locations. When the decontamination liquid recovery apparatus 100 is not provided, the decontamination liquid flows to the lower part of the RPV or the lower part of the PCV and is appropriately recovered.

  Thereafter, the first gel 64 and the second gel 66 are injected into the reactor well 20 that has been decontaminated. As shown in FIG. 20, the pole 101 may be installed in advance so as to communicate with a plurality of holes provided in the lower stage of the shield plug 6 before gel injection. By installing a pole first, various operations can be performed through this pole after the gel is injected. In addition, you may make it provide a hole directly in a gel, without installing a pole.

  As shown in FIG. 21, a plurality of holes are provided in the PCV head using a plurality of holes provided in the lower stage of the shield plug 6. Thereafter, as shown in FIG. 22, a decontamination device 60 and a decontamination liquid recovery device 100 are provided to decontaminate the space surrounded by the PCV head inner surface and the RPV head outer surface, which are the second space. By collecting the decontamination liquid collected in the second space using the decontamination liquid collection apparatus 100, it is possible to prevent the spread of contamination to other locations. When the decontamination liquid recovery apparatus 100 is not provided, the decontamination liquid flows to the lower part of the RPV or the lower part of the PCV and is appropriately recovered. Thereafter, the third gel 68 is injected into the second space. FIG. 23 shows a schematic diagram of the nuclear power plant after the third gel 68 is injected.

  In Example 2 described above, there is a possibility that the decontamination liquid may leak from the well seal bellows 65 parts or the fuel exchange bellows 67 parts. Therefore, before the decontamination work in the above embodiment, the well seal bellows 65 part and the fuel exchange bellows 67 part are repaired in advance with a gel of a predetermined thickness (which may not be a gel) to leak the decontamination solution. Preventive measures may be taken. Thereafter, a decontamination work may be performed to inject various gels into the remaining space.

  According to the second embodiment described above, when providing holes in the shield plug 6 or the like, a plurality of holes are provided, and decontamination is performed using the holes using the decontamination apparatus 60 and the decontamination liquid recovery apparatus 100. Since the decontamination solution used for the decontamination work can be collected, it is possible to prevent the spread of contamination to other locations.

  A third embodiment will be described below with reference to FIGS. The third embodiment is further different from the above-described embodiment in that the inside of the reactor is investigated using the boring device 150 after injecting various gels. A description of the same parts as those in the above-described embodiment is omitted.

  FIG. 24 shows a detailed structure of the boring device 150. The boring device 150 includes a hose / cable line 151 for supplying high-pressure water and supplying electric power as necessary, a guide pipe 152, a turning table 153 for turning the guide pipe if necessary, and a manipulator 154 for connecting the guide pipe. An elevating device 155 for elevating and lowering the guide pipe, a shielding port 157 provided in an opening when the guide pipe 152 carried in the transfer container 156 is moved to the seal box, It is comprised from the shield box 158 which comprises the isolation space. The shield box 158 further includes an electric power / control panel 159 for supplying electric power and controlling operations of various devices, an abrasive supply device 160 and an ultra-high pressure pump 161 used for AWJ disconnection. . An AWJ head 162 for performing AWJ cutting is provided at the tip of the guide pipe.

  FIG. 25 shows the detailed steps of the investigation process. The step of sealing the first space, the second space, and the third space with various gels is the same as described above. Thereafter, an internal investigation of the RPV is performed using the boring device 150. First, the boring device 150 is installed in the lower stage of the shield plug 6. Thereafter, the guide pipe is inserted into the reactor through the hole. Since the holes up to the RPV head have already been provided in the above-described operation, the guide pipe may be inserted using the holes. When the tip of the guide pipe reaches the steam dryer 11, a hole is provided by the AWJ head 162 provided at the tip of the guide pipe. It is possible to provide a hole by using AWJ water whose pressure has been increased by the ultrahigh pressure pump 161. The guide pipe is inserted into the reactor while cutting a necessary portion such as the steam separator 12.

  After inserting the guide pipe to a predetermined position, insert a radiation measuring device, temperature measuring device, pressure measuring device, fiberscope (not shown), etc., which are separately provided investigation devices inside the reactor, through the inside of the guide pipe. Investigate the inside of the reactor.

  The details of the guide pipe connection will be described with reference to FIG. As shown in FIG. 26A, a plurality of pin-like connecting members 163 are provided at the connecting portion at the upper end of the guide pipe 165. The plurality of pin-shaped connecting members 163 are provided at equal intervals in the circumferential direction at the upper end portion of the guide pipe 165. Each pin-shaped connecting member is pressed from the inside to the outside of the guide pipe 165 by a spring. The surface of the outer end portion of each pin-shaped connecting member 163 is processed into a hemispherical shape. A plurality of through holes 164 having an inner diameter that is the same as the outer diameter of the pin-shaped connecting member 163 are formed in the connecting portion at the lower end of the guide pipe 152 in the circumferential direction. These through holes 164 are formed in the circumferential direction of the lower end portion of the guide pipe 152 at the same intervals as the circumferential intervals of the pin-shaped connecting members 163 provided in the guide pipe 165. A curved surface is formed on the inner surface of the lower end portion of the guide pipe 152 from the lower end of the guide pipe 152 toward the through hole 164.

  As the elevating device 155 descends, the guide pipe 152 moves downward, and the upper end portion of the guide pipe 165 is inserted into the lower end portion of the guide pipe 152. When the curved surface formed on the inner surface of the lower end portion of the descending guide pipe 152 comes into contact with the hemispherical outer surfaces of the plurality of pin-like connecting members 163 provided on the upper end portion of the guide pipe 165, the guide pipe 152 descends. Accordingly, the curved surface presses the pin-shaped connecting member 163 toward the inside of the guide pipe 165, overcomes the outward pressing force by the spring, and the pin-shaped connecting member 163 moves toward the inside of the guide pipe 165. To do. When the through hole 164 is lowered to the position of the pin-shaped connecting member 163, the pin-shaped connecting member 163 that is pressed outward by a spring is inserted into the through-hole 164. As a result, as shown in FIG. 26B, each pin-shaped connecting member 163 is inserted into each through hole 164, and the guide pipe 152 and the guide pipe 165 are connected. These operations are performed using a manipulator 154 and an elevating device 155 provided in the shield box.

  FIG. 27 is a diagram for explaining detailed steps for inserting the guide pipe into the sheet in the RPV head. In FIG. 27, only this portion is taken out and described so that the sheet provided in the RPV head can be easily understood. FIG. 27A shows a sheet 69 in a normal state. A through-hole 170 is provided in the center of the sheet, and this through-hole 170 is normally closed by the fourth gel 70 injected into the inside (state shown in FIG. 27A). . In this embodiment, a fluid material is used as the fourth gel 70. Therefore, the through hole 170 is closed by the action of the gravity of the gel itself. When the guide pipe 152 is inserted, a conical insertion auxiliary tip 171 is attached to the tip of the guide pipe through the inside of the guide pipe, and the guide pipe is inserted into the through hole 170. At this time, since the fourth gel has fluidity, the guide pipe is inserted while the through-hole 170 provided in the sheet 69 is expanded by the insertion auxiliary tip 171 (the state shown in FIG. 27B). When various operations are completed, the guide purp is pulled out. When the pulling is performed, the through hole 170 is closed by the gravity action of the fluid gel itself (returns to the state shown in FIG. 27A). Accordingly, dust scattering can be prevented during various operations.

  In Example 3 described above, when the space is filled with various gels having a shielding effect, the shield plug can be removed. In FIG. 27, various devices are set on the shield plug to perform various operations. However, after removing the shield plug, a shield (not shown) is set there, and various devices are set thereon. You may make it carry out work.

  As in this example, the first space, the second space, and the third space surrounded by the reactor structure are sealed with various gels, and then the inside of the reactor is investigated, so that dust scattering It is possible to investigate the inside of the reactor while preventing

  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, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

1: boiling water nuclear power plant, 2: nuclear reactor, 3: PCV, 4: reactor building, 5: PCV head, 6: shield plug, 7: operating floor, 8: RPV head, 9: RPV, 10: core 11: Steam dryer, 12: Steam separator, 13: Concrete mat, 14: Pedestal, 15: Gamma ray shield, 16: DSP, 17: SFP, 18: Originally existing position, 19: Concrete mat Upper: 20: Reactor well, 21: Thermal insulation material, 51: First house, 52: Upper open / close type shielding plate, 53: Lower open / close type shielding plate, 54: Second house, 55: Equipment loading / unloading box, 56: Seal box device, 57: Crane device, 58: Seal cable, 59: Drilling device, 60: Decontamination device, 61: First hole, 62: Second hole, 63: Injection device, 64: First gel, 65: Hue Seal bellows, 66: second gel, 67: fuel change bellows, 68: third gel, 69: sheet, 70: fourth gel, 100: decontamination liquid recovery device, 101: pole, 150: boring device, 151: Hose / cable line, 152: guide pipe, 153: swivel table, 154: manipulator, 155: lifting device, 156: transfer container, 157: shielding port, 158: shield box, 159: power / control panel, 160: abrasive supply Device, 161: Ultra-high pressure pump, 162: AWJ head, 163: Pin-shaped connecting member, 164: Through hole, 165: Guide pipe, 170: Through hole, 171: Insertion auxiliary tip

Claims (10)

Viscous gel or foam material is injected into the space surrounded by the reactor well, shield plug, and PCV head provided in the reactor building through the through hole provided in the shield plug, Partly filled with gel or foam,
After the filling, the shield plug is removed and carried out to the outdoor part of the reactor building. In the method for preventing contamination expansion at the time of dismantling the power plant according to claim 1,
The gel or foam material is made of a material having a radiation shielding effect, and the method for preventing contamination expansion at the time of power plant dismantling. In the pollution expansion prevention method at the time of the power plant dismantling according to any one of claims 1 and 2,
The said gel or foaming material is comprised with several different material, The contamination expansion prevention method at the time of the power plant dismantling characterized by the above-mentioned. In the pollution expansion prevention method at the time of the power plant dismantling according to any one of claims 1 to 3,
The method of preventing contamination expansion at the time of dismantling a power plant, wherein the gel or foaming material is injected into a sheet previously provided in the space. In the pollution expansion prevention method at the time of the power plant dismantling according to any one of claims 1 to 4,
A method for preventing contamination expansion at the time of dismantling a power plant, wherein a step of taking out a nuclear reactor structure is carried out after part of the space inside the reactor building is filled with the gel or foam material. In the pollution expansion prevention method at the time of the power plant dismantling according to any one of claims 1 to 5 ,
A method for preventing contamination expansion at the time of dismantling a power plant, comprising a step of decontaminating the space. In the pollution expansion prevention method at the time of power plant dismantling of Claim 6 ,
The decontamination uses a decontamination apparatus that injects a decontamination liquid for decontamination onto a decontamination target, and a decontamination liquid collection apparatus that collects the decontamination liquid. How to prevent expansion. A step of inserting a guide pipe into the reactor after performing the method for preventing contamination expansion at the time of dismantling the power plant according to any one of claims 1 to 7 ;
A method for investigating the interior of a power plant when dismantling the power plant, wherein an investigation device is inserted into the reactor using the inserted guide pipe and the inside of the reactor is examined. In the method for preventing contamination expansion at the time of dismantling the power plant according to claim 1,
Viscous gel or foam material is injected into the space enclosed by the reactor containment vessel and the reactor pressure vessel provided in the reactor building through the through-hole provided in the PCV head, and the space inside the reactor building is A method for preventing the spread of contamination at the time of dismantling a power plant, characterized in that a part is filled with gel or foam. A gel or foam material having viscosity is injected into a space surrounded by a reactor well, a shield plug and a PCV head provided in the reactor building through a through-hole provided in the shield plug, and the gel or foam material is injected into the space. Filled with
After the filling, a method for preventing contamination expansion at the time of dismantling a power plant, wherein a nuclear reactor structure constituting a part of the space is removed and carried out to an outdoor part of the reactor building.