JP2014235009A - Carry-out method of fuel debris in boiling water nuclear power plant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method capable of carrying out fuel debris of a boiling water reactor in a short time.SOLUTION: In the present invention for solving the problems, in the carry-out method of fuel debris in a boiling water nuclear power plant, a cutoff material is injected into a reactor pressure vessel, and then the fuel debris molten in the reactor pressure vessel is carried out in the state in which water is filled in the reactor pressure vessel. An injection port is disposed in a pipe connected to the inside of the reactor pressure vessel, the cutoff material is injected through the injection port.

Description

  The present invention relates to a fuel debris retrieval method in a boiling water nuclear plant.

  In the boiling water nuclear power plant, multiple emergency cooling facilities are provided so that the core in the reactor pressure vessel is always cooled, and measures are taken to prevent a core melting accident. However, although the probability is very low, it can be assumed that the function of the emergency cooling facility is lost and the core is melted. Studies have been made on a method for extracting nuclear fuel material when such core melting occurs.

  Patent Document 1 describes a method of carrying out fuel debris from a reactor pressure vessel in an air environment. In this document, a hole is provided in the upper cover of the reactor containment vessel and the reactor pressure vessel using a boring device, and further, a steam dryer and a steam separator are bored, and boring processing is carried out to the reactor core. After injecting the shielding body into the reactor containment vessel from the hole, and confirming the radiation shielding effect of the injected shielding body, open the top cover of the reactor containment vessel and the reactor pressure vessel, and then the steam dryer Etc., and a method for carrying out fuel debris is described.

  Non-Patent Document 1 describes a method for taking out fuel debris in a boiling water nuclear power plant. In this document, in order to fill the inside of the reactor containment vessel and remove the fuel debris, the leakage location inside the reactor containment vessel is investigated in advance, and the specified leakage location is repaired to stop the water. After that, a method is described in which the inside of the reactor containment vessel is filled with water, the core is submerged, the investigation is performed, and the fuel debris is carried out.

  In Non-Patent Document 2, regarding the fuel debris when the core is melted, the position of the debris ranges from a state where it drops to the bottom of the reactor containment vessel to a state where it almost remains inside the reactor pressure vessel. It is described that there is a reaction between the molten core fuel and concrete.

JP 2013-19875 A

"Medium-to-long-term roadmap for decommissioning of TEPCO's Fukushima Daiichi Nuclear Power Station Units 1 to 4 (summary version)", [online], December 16, 2011, Ministry of Economy, Trade and Industry, [ Search on May 21, 2013], Internet <http://www.meti.go.jp/earthquake/nuclear/pdf/111221_01a.pdf> “Research plan regarding improvement of simulation code for understanding the status of fuel debris in the reactor”, [online], March 14, 2012, TEPCO, [Search May 21, 2013], Internet <http: //www.tepco.co.jp/nu/fukushima-np/roadmap/images/e120314_02-j.pdf>

  Although the technique described in Patent Document 1 is an effective technique for carrying out fuel debris in an air environment, a shield plug, a reactor containment vessel, and a reactor pressure vessel that are previously positioned above the reactor pressure vessel. It is necessary to provide a hole in the top lid and put a shielding material such as an iron ball into the reactor pressure vessel through the hole. Before starting drilling, install a work house and a preparation house on the operation floor, and further drill holes remotely. Work is required, and it is considered that it takes a long time to remove the fuel debris.

  In addition, fuel debris is carried out using a boring device that rotates and cuts. As described in Non-Patent Document 2, the molten fuel in the reactor pressure vessel is made of ceramic fuel debris and metal. It is estimated that internal structures of the reactor pressure vessel are mixed, and it is impossible to deny the possibility of problems such as the problem of the biting of the cut material when these mixtures are carried out using a boring device by rotary cutting. If one bite occurs, it may take a long time to remove the fuel.

  In the technology described in Non-Patent Document 1, it is necessary to investigate the leaked part and repair the specified leaked part for the entire area inside the reactor containment vessel, and the investigation range and the repaired part become wide, and the harsh environment It is considered that it takes a long time to take out the fuel debris because it is also a work under.

  Therefore, the problem to be solved by the present invention is to provide a construction method capable of carrying out fuel debris of a boiling water reactor in a short period of time.

  The present invention for solving the above-described problem is a method for carrying out fuel debris in a boiling water nuclear power plant, in which a water stop material is injected into the reactor pressure vessel and then the reactor pressure vessel is filled with water. The molten fuel debris is discharged into the reactor pressure vessel.

  According to the present invention, it is possible to carry out fuel debris of a boiling water reactor in a short period of time.

Diagram showing the outline of boiling water nuclear power plant The figure explaining the outline of the form of fuel debris when fuel melting occurs in a boiling water nuclear power plant The figure explaining the outline of other forms of fuel debris when fuel melting occurs in a boiling water nuclear power plant Diagram explaining the outline of the water injection system piping for emergency cooling equipment in a boiling water nuclear power plant Diagram showing the outline of the core spare purger at the boiling water nuclear power plant An enlarged view of a part of the core spare purger at the boiling water nuclear power plant The figure explaining the step which installs the water stop material injection device in the boiling water nuclear power plant The figure which shows the outline of the water stop material injection device The figure explaining the step which injects the water stop material to the boiling water nuclear power plant The figure explaining the step which raises the water level inside the reactor pressure vessel of a boiling water nuclear power plant by injecting a water stop material The figure explaining the step which decontaminates the upper lid of the containment vessel of a boiling water nuclear power plant The figure explaining the step which removes the upper cover of the containment vessel of a boiling water nuclear power plant The figure explaining the decontamination and removal step of the steam dryer and the steam separator of the boiling water nuclear power plant The figure explaining the step which installs the cutting device for crushing the fuel debris of a boiling water nuclear power plant The figure explaining the step which crushes fuel debris of a boiling water nuclear power plant The figure explaining the step which takes out the fuel debris of a boiling water nuclear power plant, and stores it in a fuel debris storage container The figure explaining the step of removing the water stop material injected into the boiling water nuclear power plant The figure explaining the step which crushes and collects fuel debris of a boiling water nuclear power plant The figure explaining the step which provides an opening in the reactor pressure vessel bottom of a boiling water nuclear power plant The figure explaining the step which injects a water stop material into the lower part of the pedestal of a boiling water nuclear power plant Diagram illustrating the steps to fill the bottom of the pedestal of a boiling water nuclear power plant The figure explaining the step which crushes and collects the fuel debris dripped at the pedestal lower part of a boiling water nuclear power plant. Diagram explaining the outline after fuel debris removal in a boiling water nuclear power plant The figure explaining the general cutting method using a cutting device Diagram explaining fuel debris crushing method for boiling water nuclear power plant The figure which shows the outline | summary of the insertion apparatus for inserting the in-core access apparatus in Example 2 in a core. The figure which shows the outline | summary of the in-furnace access apparatus in Example 2. The figure explaining the outline | summary of the access path | route of the reactor access apparatus to the inside of a reactor pressure vessel in Example 2. FIG. The figure explaining the step which provides a hole in T-box (T-shaped branch) of a core place purger in Example 2.

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

  A method for carrying out fuel debris in the nuclear power plant according to the first embodiment of the present invention applied to a boiling water nuclear power plant will be described with reference to FIGS.

  First, the schematic structure of the boiling water nuclear power plant of the present embodiment will be described with reference to FIG. 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 5 attached to the upper end. The PCV has a dry well 6 formed therein and a pressure suppression chamber 7 in which a pressure suppression pool filled with cooling water is formed. One end of the vent passage 8 communicated with the dry well is immersed in the cooling water of the pressure suppression pool in the pressure suppression chamber. A shield plug 9, which is a radiation shielding body divided into a plurality of parts, is disposed directly above the upper lid 5 of the PCV, and these shield plugs are installed on the operation floor of the reactor building.

  The nuclear reactor includes a reactor pressure vessel (hereinafter referred to as RPV 11) configured with an upper lid 10, a core 12 loaded with a plurality of fuel assemblies including nuclear fuel material, a steam separator 14 and a steam dryer 13. It has. The core, steam separator and steam dryer are located in the RPV. A core shroud 15 installed in the RPV surrounds the core. Each fuel assembly 16 loaded in the core is supported at its lower end by a core support plate 17 and at its upper end by an upper lattice plate 18. The steam separator is disposed above the upper grid plate located at the upper end of the core, and the steam dryer is disposed above the steam separator.

  A plurality of control rod guide tubes 19 are arranged below the core, and a support cylinder including a plurality of control rod guide tubes is formed. Control rods 20 that are put into and out of the fuel assemblies in the core and control the reactor power are disposed in the respective control rod guide tubes. A plurality of control rod drive mechanism housings 21 are attached to the lower mirror 22 of the RPV. A control rod drive mechanism (not shown) is installed in each control rod drive mechanism housing 21 and connected to the control rod 20 in the control rod guide tube 19. The steam / water separator 14, the steam dryer 13, the core shroud 15, the upper lattice plate 18, the core support plate 17, the support cylinder, the control rod guide tube 19, and the core shroud lower shell installed in the RPV 11 are in-core structures. It is.

  The RPV is installed on a cylindrical pedestal 24 provided on a concrete mat 23 provided at the bottom of the PCV. A cylindrical γ-ray shield 25 is installed at the upper end of the pedestal and surrounds the RPV.

  Next, FIG. 2 (a) and FIG. 2 (b) show an outline of the configuration of the fuel debris 26 when core melting occurs in the boiling water nuclear power plant. When the function of the emergency cooling facility is lost and the cooling water is not injected into the RPV, the fuel pellets in the fuel assembly and the cladding tube are melted by the decay heat of the nuclear fuel. In this case, it is presumed that the molten nuclear fuel exists on the concrete mat that is the position where it originally existed, the bottom of the RPV furnace, or the bottom of the PCV (FIG. 2A). In some cases, as shown in FIG. 2 (b), the nuclear fuel hardly remains at the position where it originally existed, and a considerable number exists on the concrete mat that is the bottom of the RPV or the bottom of the PCV. It is estimated that In such a state, it is estimated that a plurality of holes and cracks are generated in the bottom of the RPV furnace. Even if water is poured into the RPV in this state, the water poured through the holes and cracks leaks, so it is considered difficult to make the RPV flooded. However, according to Non-Patent Document 2, it is considered that the molten fuel debris is cooled in a state of being substantially in contact with water by water injection.

  The present embodiment provides a method capable of carrying out fuel debris from such a nuclear power plant in a short period of time. Although the present embodiment will be described by taking the case of FIG. 2A as an example, the present embodiment can also be applied when the fuel debris is that of FIG.

  As shown in FIG. 3, the boiling water nuclear power plant is provided with an emergency core cooling device for cooling the core in an emergency. This emergency core cooling apparatus is provided with two CS-system water injection pipes 27 (only one pipe is shown) of a high-pressure water injection system and a low-pressure water injection system. Each system is connected to a core spray line 28 provided in the RPV so that cooling water can be injected in an emergency. In addition, valves are provided at two locations in the middle of the CS-based water injection pipe 27.

  In this embodiment, a water stop material is injected into the core using the CS-type water injection pipe 27 directly connected to the core. Thereby, it is possible to seal or prevent the leakage of water from the RPV, or to reduce it as much as possible, by sealing the holes and cracks generated at the bottom of the RPV furnace without opening the upper lids of the PCV and RPV. If the leakage of water from the RPV can be stopped or reduced as much as possible, the inside of the RPV can be submerged, and even if the upper lid of the PCV and RPV is opened, the radioactive material is not scattered and further shielded. Since it also has an effect, the fuel debris retrieval work period can be shortened.

  FIG. 4A shows the details of the core place purger provided inside the RPV. The core sparger is composed of a core spray line 28 and a sparger nozzle 29. FIG. 4B shows a partially enlarged view of the core spare purger. As shown in FIG. 4B, the CS-based water injection pipe 27 and the core spray line 28 are connected by a T-box 30 (T-shaped branch).

  Next, details of the steps for injecting the water stop material will be described. As shown in FIG. 5, a water stop material injection device 31 is provided for injecting a water stop material into the CS water injection pipe 27 of either the high pressure water injection system or the low pressure water injection system. When connecting the water stop material injection device to the pipe, the valve provided in the middle of the pipe is closed. This is to prevent radioactive materials in the RPV from leaking outside. The water stop material injection device 31 is connected to the CS water injection pipe by welding or the like.

  FIG. 6 shows the details of the water stop material injection device 31. The water-stop material injection device is configured such that a seal box device 33 is connected to a connection pipe 32 provided by welding or the like in a part of the water injection system pipe that is perforated. Furthermore, it has the water stop material supply apparatus 34 which supplies a water stop material to a seal box apparatus. The seal box device 33 has a sealed structure, and is configured so that radioactive materials are not leaked from the connection pipe 32. Further, the seal box device 33 is provided with an injection nozzle 35 for injecting a water stop material.

  When the installation of the water stop material injection device is completed, the valve is opened, and the water stop material is injected into the reactor core together with water. FIG. 7 shows details of the water stopping material injection step. Since the CS-type water injection pipe of the high-pressure water injection system or the low-pressure water injection system is directly connected to the reactor core, the water stop material 36 can be injected into the RPV through this pipe. Here, iron powder was used as the water stop material. When iron powder is used, it can also be used as a shielding material. The waterstop material is not limited to iron powder, and other materials may be used. B4C (boron carbide) or cement may be used. Moreover, the water stop material uses the thing of the magnitude | size of various particle sizes here. This is because by changing the particle size of the water-stopping material, the water-stopping material enters the holes and cracks, so that a water-stopping effect can be obtained.

  FIG. 8 shows an enlarged view of the bottom of the RPV furnace when the water stop material is injected. At the bottom of the RPV furnace, it is presumed that some holes and cracks are caused by the molten fuel. It is estimated that a hole or the like is generated in the welded portion between the in-core monitor housing 37 and the RPV furnace bottom or the welded portion between the CRD stub tube 38 and the RPV furnace bottom, thereby causing water leakage. In this embodiment, this leakage is prevented by injecting a water stop material.

  As a first water-stopping material injection step, a water-stopping material having a large particle size is injected. As the second water stop material injection step, a water stop material having a size smaller than that of the water stop material injected in the first water stop material injection step is injected. Further, as the third water stop material injection step, a water stop material smaller than the water stop material injected in the second water stop material injection step is injected. By repeating such steps and injecting water from a large particle size water stop material to a small particle size water stop material into the RPV furnace bottom, water leakage occurring at the bottom of the RPV furnace is stopped or minimized. It becomes possible to stop. If water leakage can be prevented, the water surface 39 inside the RPV will also rise. When the RPV is filled with water, proceed to the next step.

  In this embodiment, since the water-filled portion is minimized with respect to the inside of the RPV, the work efficiency can be improved by minimizing the number of portions to be repaired as compared with the case where the inside of the PCV is submerged. Further, if the inside of the PCV is to be submerged, it is possible to minimize the number of contaminated portions of the radioactive material due to the contaminated water, compared to the case where the submergence cannot be performed.

  Here, when the water stoppage or leakage water can be minimized, it is necessary to forcibly circulate the cooling water in order to continue cooling the fuel debris. Although not shown in the figure, the cooling water is discharged from the recirculation outlet nozzle, and cooling is performed using a circulation line that injects the cooling water from the water supply system pipe. Alternatively, if the recirculation outlet nozzle cannot be used, the cooling water is circulated through the usable line.

  When the water filling in the RPV is completed, as shown in FIG. 9, before opening the upper cover of the PCV, the inner surface of the upper cover of the PCV is decontaminated by a decontamination apparatus 40 that injects high-pressure water. After the decontamination, as shown in FIG. 10, the shield plug provided on the upper part of the PCV is removed by the crane 41 provided separately, and then the upper lid of the PCV is removed. Although not shown in the figure, decontamination of the RPV upper lid is performed by the decontamination apparatus 40 that injects high-pressure water before removing the upper lid of the RPV. Even if the upper lid of the RPV is opened, since water is stretched inside the RPV, the radioactive dust is prevented from being scattered and further has a shielding effect.

  Thereafter, the reactor well 42 may be filled with water as shown in FIG. If there is a crack at the connection between the PCV 3 and the reactor well 42, the crack is repaired and the water is filled. Thereafter, the steam dryer and the steam / water separator in the RPV are decontaminated by the decontamination apparatus 40 that injects high-pressure water, and then removed. The core spray line 28 and the sparger nozzle 29 arranged in an annular shape in the nuclear reactor may also be removed.

  Thereafter, as shown in FIG. 12, a cutting device 43 for cutting the fuel debris 26 is installed in the RPV. For example, it is possible to employ a cutting device using high-pressure water. In addition to this, a laser cutting device may be used. Moreover, you may cut | disconnect using the abrasive water jet (AWJ) which added the abrasives to the high-speed water jet. By using B4C as an abrasive material, cutting becomes possible while preventing the criticality of fuel debris. This embodiment is characterized in that a non-contact cutting device is used. This is because in the case of rotary cutting, there is a problem of biting of the cut object.

  When the installation of the cutting device 43 is completed, the fuel debris is crushed as shown in FIG. The cutting device is configured to be remotely operable from above. Next, the cut fuel debris 44 is grasped by using a fuel debris gripping tool 45 and collected in a separately provided fuel debris storage container 46 (FIG. 14). In the present embodiment, the fuel debris is taken out using the gripping tool 45, but it is also possible to collect it with a suction recovery device using a pump. When the removal of the fuel debris remaining in the upper part of the RPV is completed, the process proceeds to the next step.

  Next, the shielding device 47 is installed in the RPV. As the shielding device, there is used a shielding device having a sufficient thickness that has a shielding effect of radiation from fuel debris even without water. The shielding device 47 has a structure in which a shielding material such as water can be put inside. That is, a function of changing the shielding effect by putting in and out the shielding material is provided. This is because workability is improved by including a shielding material that can provide an appropriate shielding effect depending on the dose rate at the work location. Considering only the shielding effect, if the heavier one is more effective (for example, 0.1 mSv / h or less), it is sufficient as a shielding body. Therefore, workability is improved by making it possible to insert an appropriate amount of shielding material each time.

  When the installation of the shielding device 47 is finished as shown in FIG. 15, the water inside the RPV is then drained, which can be drained using a pump or the like. Since a shielding device is provided in the RPV, it is possible to prevent leakage of radiation even if water is drained. Thereafter, the water stop material injected into the bottom of the RPV furnace is also removed. This removes the water stop material using the water stop material recovery device 64. The reason why the water-stopping material is removed here is that the amount of waste increases when the water-stopping material is mixed in the fuel debris.

  Thereafter, as shown in FIG. 16, the access device 48 provided at the bottom of the shielding device 47 is used to crush the fuel debris 26 with the cutting device 43 using high-pressure water, and the gripping device for the fuel debris after crushing is used. Used to recover to the fuel debris storage container 46. Although not shown, the shielding device 47 has an opening / closing lid for storing the fuel debris storage container. The access device 48 is configured to be operated by remote control.

  When recovery of fuel debris at the bottom of the RPV furnace is completed, a through hole 49 is provided in the bottom of the furnace (FIG. 17). As shown in FIG. 18, a shielding material 50 for shielding radiation is injected through the through hole 49. Further, the openings provided in the pedestal are also closed using the concretes 51 and 52. Thereafter, water is injected and the entire bottom of the RPV furnace is removed.

  Once the entire RPV furnace bottom is removed, the shielding device is further removed. Although not shown, a recirculation line for circulating the cooling water is provided as necessary. This state is shown in FIG. Thereafter, the shielding material is removed, the fuel debris is crushed using the cutting device 43, the crushed fuel debris pieces are taken out, collected into the fuel debris storage container 46, and the debris fuel is taken out.

  FIG. 21 shows a schematic diagram of the PCV after carrying out the fuel debris. The fuel debris removal is completed by such a series of operations.

  FIG. 22 shows details of the fuel debris crushing method. Conventionally, for cutting using AWJ or laser, a method of cutting through a certain plate thickness has been adopted. In carrying out the fuel debris in the present embodiment, the thickness of the molten fuel debris is unknown, and it is considered to be a certain lump state. When the conventional cutting method is adopted, there is a possibility that the cut piece cannot be cut off because the cutting cannot be performed. Therefore, in this embodiment, in both high-pressure water cutting and laser cutting without using AWJ and abrasive cutting, the idea of hanging from the surface is adopted instead of the idea of penetrating from the surface, and the cut is surely made little by little. I decided to adopt the idea of dropping down in detail.

  Conventionally, cutting has been performed using a cutting device approximately perpendicularly to the cutting object 53 as shown in FIG. 22 (a), but in this embodiment, cutting is performed from an oblique direction as shown in FIG. 22 (b). I tried to do it. By doing in this way, even if the thickness of the object to be crushed is thick, it is possible to reliably crush sequentially from the surface of the object.

  According to the present embodiment described above, the fuel debris of the boiling water reactor can be carried out in a short period of time. The construction period can be shortened by flooding only the RPV and flooding it.

  A method for carrying out fuel debris in the nuclear power plant of Example 2 applied to a boiling water nuclear power plant according to the present invention will be described with reference to FIGS. In addition, description of the same part as Example 1 is abbreviate | omitted.

  In the second embodiment, the sparger nozzle 29 of the core spray line 28 may become an obstacle during the injection of the water stop material, and it may be difficult to earn the water stop material. Therefore, in the present embodiment, the point that the water stop material is injected by providing a hole in the T-box 30 (T-shaped branch) of the core place purger is changed from the first embodiment. Since other work steps are the same as those in the first embodiment, description thereof is omitted.

  FIG. 23 shows a detailed view of the insertion device 54. The insertion device has a seal box device 55 and a water stop material supply device 56. A feed mechanism 58 of an access device 57 is provided inside the seal box device 55. The seal box device is hermetically sealed so that radioactive substances do not leak when the seal box device is connected to the CS-based water injection pipe 27.

  FIG. 24 shows details of the access device. At the tip of the access device, a camera (not shown), a gripping tool 59, a cutting device 60 (laser cutting device, high-pressure water cutting device), and a water stop material injection line 63 are provided. A plurality of these devices may be provided, or may be provided in combination, or a single device may be provided. An angle adjusting mechanism 61 is provided so that the angle of the tip can be changed. A roller 62 may be provided. As the roller rolls inside the CS-based water injection pipe 27, the insertability of the access device is improved. Moreover, you may provide a fixing device (not shown) so that the cutting device 60 may not move.

  FIG. 25 shows an access path when the access device is inserted into the CS water injection pipe 27 of the boiling water nuclear plant. The access device is inserted into the CS-based water injection pipe 27 using the feed mechanism 58, and the feed device 58 feeds the access device into the T-box 30 provided in the core sparger.

  Then, as shown in FIG. 26, the through-hole 64 is provided in the T-box 30 using the cutting device 60 provided in the front-end | tip part of the access device. It becomes possible to inject the water stop material directly into the core through the through hole 64.

  According to the present embodiment described above, the fuel debris of the boiling water reactor can be carried out in a short period of time. By filling the RPV with water and making it submerged, the construction period can be shortened. Furthermore, it becomes possible to inject a water-stopping material into the core without using a sparger nozzle, so that fuel can be taken out more reliably. .

DESCRIPTION OF SYMBOLS 1 ... Boiling water-type nuclear power plant, 2 ... Reactor, 3 ... PCV, 4 ... Reactor building, 5 ... Top cover, 6 ... Dry well, 7 ... Pressure suppression chamber, 8 ... Vent passage, 9 ... Shield plug, 10 ... Upper lid, 11 ... RPV, 12 ... core, 13 ... steam dryer, 14 ... gas / water separator, 15 ... core shroud, 16 ... each fuel assembly, 17 ... core support plate, 18 ... upper grid plate, 19 ... control Rod guide tube, 20 ... control rod, 21 ... control rod drive mechanism housing, 22 ... lower mirror, 23 ... concrete mat, 24 ... pedestal, 25 ... gamma ray shield, 26 ... fuel debris, 27 ... CS water injection pipe, 28 ... Core spray line, 29 ... Sparger nozzle, 30 ... T-box, 31 ... Water stop material injection device, 32 ... Connection pipe, 33 ... Seal box device, 34 ... Water stop material supply device, 35 ... Injection nozzle, 36 ... still water 37 ... In-core monitor housing, 38 ... CRD stub tube, 39 ... Water surface inside the RPV, 40 ... Decontamination device, 41 ... Crane, 42 ... Reactor well, 43 ... Cutting device, 44 ... Cut fuel debris, 45 DESCRIPTION OF SYMBOLS ... Fuel debris holding tool, 46 ... Fuel debris storage container, 47 ... Shielding device, 48 ... Access device, 49 ... Through-hole, 50 ... Shielding material, 51, 52 ... Concrete, 53 ... Cutting object, 54 ... Insertion device 55 ... Seal box device, 56 ... Water stop material supply device, 57 ... Access device, 58 ... Feed mechanism, 59 ... Gripping tool, 60 ... Cutting device, 61 ... Angle adjustment mechanism, 62 ... Roller, 63 ... Water stop material Injection line, 64 ... Waterstop material recovery device

Claims (12)

In a method for carrying out fuel debris in a boiling water nuclear power plant,
A fuel debris unloading method, comprising: injecting a water stop material into a reactor pressure vessel, and unloading molten fuel debris into the reactor pressure vessel in a state where water is filled in the reactor pressure vessel. The method for carrying out fuel debris according to claim 1,
A method for carrying out fuel debris, wherein an injection hole is provided in a pipe connected to the inside of the reactor pressure vessel, and a water stop material is injected from the injection hole. The method for carrying out fuel debris according to claim 1 or 2,
The method for carrying out fuel debris, wherein the water blocking material is a material having a shielding effect. The method for carrying out fuel debris according to claim 1,
The fuel debris carrying-out method according to claim 1, wherein the water-stopping material is injected in a granular shape to change the particle size. The method for carrying out fuel debris according to claim 1,
A method for carrying out fuel debris, wherein the water stop material is mixed into water and injected into a reactor pressure vessel. The method for carrying out fuel debris according to claim 2,
Pass the access device into the pipe through the injection hole,
A fuel debris carry-out method, wherein a water-stopping material is injected into a reactor pressure vessel through a water-stopping material injection device connected to the access device. The method for carrying out fuel debris according to claim 6,
The method for carrying out fuel debris, wherein the water stop material injection device comprises a monitoring camera, a water stop material injection tube, a laser cutting head, a high-pressure water cutting head, or an abrasive water jet device injected with an abrasive material. The method for carrying out fuel debris according to claim 1,
After discharging the first fuel debris, a shielding device capable of changing the shielding effect function by changing the injection amount of the shielding material is inserted into the reactor pressure vessel, and the shielding device is installed in the reactor pressure vessel. A fuel debris carrying-out method, wherein the fuel debris is collected in an inserted state. In a method for carrying out fuel debris in a boiling water nuclear power plant,
A method for carrying out fuel debris, characterized by using a non-contact type fuel debris crusher that does not directly contact fuel debris. The method for carrying out fuel debris according to claim 9,
The fuel debris crushing apparatus uses a laser, high-pressure water, or an abrasive water jet into which an abrasive material is injected. The method for carrying out fuel debris according to claim 10,
The laser or high-pressure water emits energy of laser or high-pressure water at a plurality of different angles with respect to the vertical axis, and digs downward in the vertical direction while crushing the surface of the fuel debris. The method for carrying out fuel debris according to claim 7, 10 or 11,
A method for carrying out fuel debris characterized by using B4C as an abrasive material.