JP6032689B1 - Fuel debris retrieval method - Google Patents

Abstract

Provided is a method and an apparatus that can be accessed from the upper part of a nuclear reactor and take out fuel debris in the air while shielding radiation using a shielding material that can be shielded flexibly according to the shape and dose of the radiation source. To do. Prior to a drilling or cutting process of a nuclear reactor containment vessel, a pressure vessel, internal structures disposed inside these, and fuel debris leaked into the pressure vessel, the drilling or cutting is performed. A step of forming a shielding layer by placing a shielding material made of magnetic steel balls on the upper end surface of at least one of the containment vessel 14, the pressure vessel 20 and the furnace internal structure in the space above the object; and drilling in the object Alternatively, a process of forming a work space for drilling or cutting by adhering a shielding material at an upper position of a planned cutting position with an electromagnet, lifting and separating, and drilling or cutting an object from above through this work space And a step of lifting and taking out a section of an object cut by drilling or cutting by drilling. [Selection] Figure 2

Description

  The present invention relates to a reactor pressure vessel in the air while shielding radiation from a reactor that has melted a core using a shielding material that can be shielded flexibly according to the shape and dose of a radiation source such as fuel debris. The present invention relates to a fuel debris retrieval method capable of taking out fuel debris inside and outside the pedestal and in-furnace structures.

  Patent Document 1 proposes a molten fuel take-out device that can safely take out molten fuel collected at the bottom of the reactor pressure vessel and the bottom of the containment vessel in water by remote operation.

  However, the molten fuel take-out device cannot be applied to take-out in the air, and the center of the operating floor must be opened during operation. There was a problem that the radioactive material would be filled up to.

JP 2013-195309 A

  The present invention provides a method of accessing fuel from the upper part of a nuclear reactor and taking out fuel debris in the air while shielding radiation using a shielding material that can be shielded flexibly according to the shape and dose of the radiation source. This is the issue.

The present invention includes (1) a pressure vessel for storing a reactor core, a storage vessel for storing the pressure vessel, and a reactor cavity surrounding the containment vessel, and a containment vessel head at an upper end of the containment vessel Is a method for removing fuel debris accumulated in the lower part of the pressure vessel and the bottom of the containment vessel in a reactor covered with a shield plug, the reactor containment vessel, the reactor pressure vessel, and The fuel debris is taken out by drilling and cutting the internal structure located inside the reactor and the fuel debris leaked into or outside the reactor pressure vessel or pedestal, and lifting it to a height above the reactor operating floor. Before the drilling or cutting step, the reactor containment vessel, the reactor pressure vessel and the internal structure in the space above the object to be drilled or cut Kutomo one of the upper end surface, magnetic in actual steel balls, packed magnetic hollow steel spheres, 2-4 times atmospheric diameter magnetic hollow steel ball having a diameter of diameter the magnetic hollow steel ball, the magnetic in solid steel ball A step of forming a shielding layer by placing a shielding material made of any one of ellipsoidal shaped shielding bags made of cloth bags, and adhering the shielding material at an upper position of a hole to be drilled or cut in the object by an electromagnet. And lifting and separating from the shielding layer to form a working space for drilling or cutting, working step of drilling or cutting the object from above through the formed working space, A step of lifting and taking out a section of the object cut or cut by drilling, a step of filling an annular space surrounding a side surface of the object with the shielding material to form an annular shielding layer, and the object After the end of the cutting operation, the annular shielding layer Lifting the shielding member constituting adsorbed by the electromagnet, Ri Na comprises a step of taking out, a step of forming the shielding layer, between the containment vessel upper part and the reactor inner circumferential surface of the cavity, A step of dropping the magnetic hollow large steel ball to form a containment container upper end portion shielding layer, and a shielding material comprising the ellipsoidal shielding bag is simply laid together with the bag on the containment vessel upper end portion shielding layer. A step of forming a top shielding layer, wherein the annular shielding layer is formed in a magnetic hollow so as to be within a limit value at which a shroud is plastically deformed inward by a weight in an annular shroud gap having a narrow filling place. comprising the step of forming a shroud head shielding layer by filling a small steel balls as a shielding material, the fuel debris removal how to characterized in that solves the above problems.

  The present invention also includes (2) a pressure vessel for storing the reactor core, a containment vessel for housing the pressure vessel, and a reactor cavity surrounding the containment vessel, and storing the upper end of the containment vessel. A method for removing fuel debris accumulated in a lower portion of the pressure vessel and a bottom portion of the containment vessel in a nuclear reactor in which the upper portion of the vessel head is covered with a shield plug, and penetrates from the upper side to the lower side of the shield plug. Drilling a plurality of working holes, and penetrating from the working holes at least the storage container head at the upper end of the storage container and the pressure container head at the upper end of the pressure container in the pressure container. A step of drilling a through hole from above in the core superstructure up to a position above the shroud head at the upper end of the shroud; and a decontamination water nozzle through the work hole and the shield plate Further, through the through-hole, projecting into the containment vessel and the pressure vessel and spraying decontamination water, at least the shield plug lower side surface, the reactor cavity upper inner peripheral surface An upper decontamination step for decontaminating the inner and outer surfaces of the containment vessel head and the inner and outer surfaces of the pressure vessel head, and a shielding material dropping pipe hanging from the through hole, and a shielding material made of magnetic steel balls from the lower end. Filling a ring shroud gap between the outer peripheral surface of the shroud and the inner peripheral surface of the pressure vessel and forming a shroud head shielding layer covering the upper surface of the shroud head, and through the through hole, Dropping a shielding bag containing a plurality of magnetic steel balls to form an upper shielding layer over the upper surface of the upper structure of the core portion above the shroud head; and through the through hole, the pressure A pressure vessel upper end portion that shields the upper end portion of the pressure vessel excluding the top portion of the pressure vessel head by dropping a shielding material made of a magnetic steel ball between the upper end portion of the reactor and the inner peripheral surface of the reactor cavity around it Forming a shielding layer; and dropping a shielding bag similar to the above onto the top of the pressure vessel head and the top surface of the pressure vessel upper end shielding layer to shield the top and the top surface of the shielding material to shield the top. A step of forming a layer, a step of lifting and removing the shield plug, a containment vessel head cutting step of cutting the containment vessel head by a manipulator, and cutting of the cutting operation before the containment vessel head cutting step After the step of removing the shielding bag and the pressure vessel upper end shielding layer on the line, and the storage container head cutting step, the shielding bag and the pressure vessel on the cut storage container head Removing the upper-end shielding layer; removing the cut-out storage container head; and after the removal process, on the heat insulation cover located between the storage container head and the pressure container head. Dropping the same shielding bag to form a heat insulating cover shielding layer, cutting the duct connected to the heat insulating cover, and then lifting and removing the heat insulating cover, and the pressure A flange bolt washer cutting step of cutting a flange bolt washer connected to the outer periphery of the pressure vessel of a flange provided on the upper outer periphery of the vessel head; and a pressure vessel head removing step of lifting and removing the pressure vessel head; Forming a core through hole in the shroud head by passing through the through hole and further penetrating the shroud head shielding layer; and the core through hole And filling the core with a shield made of a large number of magnetic steel balls, dropping a shielding bag similar to the above to form a core top surface shielding layer on the core top surface, and A step of removing the shroud head shielding layer, and a fuel debris extraction device provided with a manipulator for cutting out fuel debris and in-furnace structures from above and adsorbing the shielding materials from above are located at the top in the core. Adsorbing the shielding material, cutting out the in-furnace structure and fuel debris from above, and lifting and removing the adsorbed shielding material and the cut out fuel debris and in-furnace structure. The method solves the above problems.

  According to the present invention, when drilling or decontaminating the reactor internals sequentially from the upper part of the reactor, or when cutting the reactor internals and fuel debris, using a magnetic steel ball as a shielding material, The radiation is optimally shielded according to the shape and dose of the object, and before work, the magnetic steel balls necessary for the work are adsorbed and removed, and the work is performed while shielding the remaining magnetic steel balls. The magnetic steel ball is quickly adsorbed and repeatedly pulled up, and the fuel debris can be removed safely and reliably.

1 is a block diagram showing a schematic structure of a nuclear reactor for carrying out a fuel debris retrieval method according to an embodiment of the present invention. Sectional drawing which shows typically the nuclear reactor used as the object which implements the fuel debris extraction method which concerns on the Example of this invention Flowchart showing first and first fifth of execution steps of the fuel debris retrieval method Flowchart showing second and first fifth of execution steps of the fuel debris retrieval method The flowchart which shows the 3rd and 1/5 of the implementation process of the fuel debris removal method Flowchart showing fourth and first fifth of execution steps of fuel debris retrieval method Flowchart showing fifth and first fifth of execution steps of fuel debris retrieval method Sectional view similar to FIG. 2 showing a state in which a drilling device is installed on the shield plug The top view which shows the work hole drilled by the drilling apparatus Sectional view similar to FIG. 2 showing a state in which the decontamination nozzle is inserted into the working hole 2 is a cross-sectional view similar to FIG. Sectional view similar to FIG. 2 showing a state in which the shielding material is dropped by the shielding material filling device Cross-sectional view schematically showing the state in which shielding material is laid in the reactor Front view showing shielding materials A to C Front view with partial cross section showing shielding material D The top view which shows typically the relationship between shielding material A and B 2 is a cross-sectional view similar to FIG. 2 showing a state in which the shielding material A is placed at the center of the three shielding materials B 2 is a cross-sectional view similar to FIG. 2 showing a state in which a shroud shielding layer, a shroud head shielding layer, and a steam / water separator shielding layer are formed. 2 is a cross-sectional view similar to FIG. 2 showing a state in which a steam dryer shielding layer, a containment vessel upper end shielding layer, a reactor cavity shielding layer, and a containment vessel top shielding layer are formed. 2 is a cross-sectional view similar to FIG. 2 showing a state in which the shield plug is lifted and carried out of the building through the slide shielding plate. 2 is a cross-sectional view similar to FIG. 2 showing a state in which the manipulator for removing the upper structure is installed on the slide shielding plate. Front view showing the structure of the manipulator for removing the superstructure Side view showing configuration of manipulator for removal of superstructure The perspective view which shows the state which attached the lifting electromagnet to the arm tip of the manipulator for superstructure removal Sectional view similar to FIG. 2 showing a state in which the containment vessel head is cut and lifted by the manipulator for removing the superstructure Sectional view similar to FIG. 2 showing a state in which the storage container head storage box is installed on the slide shielding plate Sectional view similar to FIG. 2 showing a state where the cut containment container head is lifted 2 is a cross-sectional view similar to FIG. 2, showing a state in which the storage container head is placed on the slide shielding plate and moved to the carry-out position. 2 is a cross-sectional view similar to FIG. 2 showing a state in which a duct connected to the heat insulating cover is cut by the manipulator for removing the superstructure. 2 is a cross-sectional view similar to FIG. 2 showing a state in which the heat insulation cover storage box is moved above the heat insulation cover. 2 is a cross-sectional view similar to FIG. 2 showing a state where the heat insulation cover is lifted and moved into the heat insulation cover storage container. 2 is a cross-sectional view similar to FIG. 2 showing a state in which the heat insulation cover and the heat insulation cover storage box are lifted and carried out. 2 is a cross-sectional view similar to FIG. 2 illustrating a state in which a pressure vessel head shielding layer before lifting is formed and a flange bolt or the like is cut by a manipulator for removing an upper structure. FIG. 2 is a cross-sectional view similar to FIG. Sectional view similar to FIG. 2 showing a state where the steam dryer storage box has been moved directly above the steam dryer Photo showing the state of removing the steam dryer and steam separator 2 is a cross-sectional view similar to FIG. 2 showing the state where the steam dryer is lifted until it is stored in the steam dryer storage box. 2 is a cross-sectional view similar to FIG. 2 showing a state where the slide shielding plate on which the steam dryer is mounted is moved onto the DS pit. Sectional view similar to FIG. 2 showing a state in which the steam dryer is decontaminated with decontamination water in the decontamination tank 2 is a cross-sectional view similar to FIG. 2 showing a state in which the steam dryer is decontaminated with decontaminated water in the DS pit and then transported. Sectional view similar to FIG. 2 showing a state in which a core through hole is drilled in the shroud head FIG. 2 is a cross-sectional view similar to FIG. 2 showing a state where the fixing bolt to the pressure vessel of the steam separator is removed by the manipulator for removing the superstructure. Sectional view similar to FIG. 2 showing the process of lifting the steam separator with an overhead crane Sectional drawing similar to FIG. 2 which shows the state which lifts a steam-water separator and accommodates in a steam-water separator storage box FIG. 2 is a cross-sectional view similar to FIG. 2 showing a state in which the air / water separator is moved above the decontamination tank while being accommodated in the air / water separator storage box. Sectional view similar to FIG. 2 showing the state of decontamination of the steam separator in the decontamination tank 2 is a cross-sectional view similar to FIG. 2 showing a state in which the air / water separator is decontaminated and lifted together with the air / water separator storage box and carried out. 2 is a cross-sectional view similar to FIG. 2 showing a state where a flange lid for opening and closing the upper part of the core is installed. 2 is a cross-sectional view similar to FIG. 2 showing a state in which the fuel debris retrieval device is installed on the slide shielding plate. Plan view showing fuel debris retrieval device and flange lid FIG. 2 is a cross-sectional view similar to FIG. 2, showing a state immediately before the flange lid is opened and the fuel debris retrieval device is lowered. Sectional view similar to FIG. 2 showing a state immediately before the start of removal of the shroud shielding layer 2 is a cross-sectional view similar to FIG. 2 showing a state in which the shroud shielding layer is removed by adsorption, and the reactor internal structure and fuel debris are cut out and lifted up. 2 is a cross-sectional view similar to FIG. 2 showing the process of putting the suspended internal structure and fuel debris into the transfer container and storing them in the equipment storage pit. FIG. 2 is a cross-sectional view similar to FIG. 2, showing the fuel debris retrieval device approaching the pressure vessel lower mirror. 2 is a cross-sectional view similar to FIG. 2 showing a state where a through hole for dropping a shielding material is formed in the outer peripheral portion of the pressure vessel lower mirror. 2 is a cross-sectional view similar to FIG. 2 showing a state in which a control rod drive mechanism and a pressure vessel lower mirror are integrally installed in the core. 2 is a cross-sectional view similar to FIG. 2 showing a state in which a shielding material layer is formed on the CRD exchange device and the pedestal floor between the upper surface of the pressure vessel lower mirror and the integral suspension. Sectional view similar to FIG. 2 showing a state where the pressure vessel lower mirror and the CRD are integrally lifted in the CRD integrated storage box by the wire of the large crane FIG. 2 is a cross-sectional view similar to FIG. 2 showing a state in which a through hole is formed in the outer periphery surrounding the CRD nozzle by the fuel debris retrieval device. Sectional view similar to FIG. 42C showing a state where the periphery of the pressure vessel lower mirror is cut by the fuel debris retrieval device Sectional drawing similar to FIG. 42C which shows the state which installed the lifting tool which lifts a pressure vessel lower mirror Sectional view similar to FIG. 2 showing a state in which the fuel debris and CRD exchanging device is cut and lifted by the fuel debris retrieval device Sectional view similar to FIG. 2 showing a state in which fuel debris flowing out from the pedestal section inspection passage is removed FIG. 2 is a cross-sectional view similar to FIG. 2 showing a state in which fuel debris flowing out from the pedestal section inspection passage is cut and removed by a self-propelled manipulator. Sectional view similar to FIG. 2 showing a state in which the flange lid, the center of the operating floor, the temporary opening, etc. are closed Front view schematically showing the configuration of the shielding material filling device Sectional drawing which expands and shows the manipulator apparatus which comprises a part of fuel debris extraction apparatus The perspective view which shows the lifting electromagnet attached to the manipulator arm and its front-end | tip The perspective view which shows the core boring attached to the manipulator arm and its front-end | tip Block diagram showing an operation control device for remotely controlling equipment such as a fuel debris retrieval device

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[Example]
First, with reference to FIG. 1, the structure of the nuclear reactor 10 used as the object which implements the fuel debris extraction method which concerns on the Example of this invention is demonstrated.

  Here, the term “reactor” includes the reactor cavity, the containment vessel, and the internal structure.

  The nuclear reactor 10 includes a nuclear reactor containment vessel (hereinafter referred to as a containment vessel or PCV) 14 surrounded by a biological shielding wall 12 on a concrete foundation installed on the ground, and a pedestal floor 16 provided at the bottom of the containment vessel 14. A cylindrical biological shield 18 standing on the pedestal floor 16 and a reactor pressure vessel (hereinafter referred to as a reactor pressure vessel) surrounded by the containment vessel 14 with its upper end protruding upward from the cylindrical biological shield 18. , A pressure vessel or RPV) 20, a control rod drive mechanism 22 provided by being surrounded by a cylindrical biological shield 18 below the lower end of the pressure vessel 20, and a core portion 24 in the pressure vessel 20. A shroud 26, a control rod guide tube 28 disposed at the inner lower end of the pressure vessel 20 on the lower side of the shroud 26, and a reactor core upper structure sequentially disposed above the shroud 26 from the lower side. Standpipe 30, a steam separator 32 and steam dryers 34..

  Reference numeral 110 in FIG. 1 indicates fuel debris, but its position is an estimate.

  The storage container 14 has a storage container spherical shell part 14A in the lower half, a storage container cylindrical part 14B in the upper half, and a storage container head 14C in the upper part of the hemisphere. The upper end portion of the pressure vessel 20 is a pressure vessel head 20A.

  The space above the containment vessel head 14C is closed by the shield plug 36, and the space between the lower surface of the shield plug 36 and the containment vessel head 14C is a reactor cavity 38.

  The periphery of the shield plug 36 is a horizontal operating floor (hereinafter referred to as an operation floor) 40 continuous with the upper surface of the shield plug 36 so that various operations can be performed.

  As shown in FIG. 2, the upper part of the operation floor 40 is covered with a nuclear reactor building 42, and an overhead crane 44 is disposed in the nuclear reactor building 42 above the shield plug 36 and the operation floor 40. Yes.

  A barrier 46 that covers the shield plug 36 and the operation floor 40 is provided below the overhead crane 44. Reference numeral 47 in FIG. 2 denotes a surrounding shielding plate provided outside the side wall of the barrier 46.

  Inside the barrier 46, a transfer container crane 48 is arranged near the ceiling. 2, the barrier opening 50A is provided above the operation floor 40 on the right side of the shield plug 36 in FIG. 2, and the wire of the overhead crane 44 is provided above the central portion of the shield plug 36. A wire lifting opening 50B is provided for passing through.

  A temporary container opening 42 </ b> A larger than the barrier opening 50 </ b> A is provided in the ceiling portion of the reactor building 42 just above the barrier opening 50 </ b> A in the barrier 46.

  The container temporary opening 42A and the barrier opening 50A can be freely opened and closed by opening and closing panels 42B and 50C, respectively.

  In FIG. 2, an equipment storage pit (hereinafter referred to as DS pit) 52 is disposed below the operation floor 40 on the right side of the shield plug 36, and a spent fuel pool 54 is disposed below the left side of the shield plug 36. Has been placed. In FIG. 2, reference numeral 55 denotes a heat retaining cover that is placed on the pressure vessel head 20A from above.

  In order to carry out the fuel debris retrieval method according to the present embodiment, various devices, shielding materials, and the like are used. Of these, main devices and equipment for fuel debris retrieval will be described. Other devices and equipment will be described sequentially along the fuel debris retrieval process.

Major components, equipment, and facilities related to fuel debris retrieval:
1. 1. fuel debris retrieval device; 2. Fuel debris storage can and transfer container; 3. punching device and shielding material filling device; 4. Manipulator for removing superstructure, Self-propelled manipulator, 6. 6. Slide shield plate, Barrier facilities, 8. 8. Reactor air purification equipment, 10. Fuel debris cooling water purification equipment Other facilities.

1-1. The specifications of the fuel debris retrieval device are as follows.
(1) A 100-ton overhead crane can be used in the reactor building, and the height from the operating floor to the crane hook is about 12 m (the bottom is about 8 m).
(2) Electricity, water supply (washing water, cooling water) and compressed air of the required capacity can be used.
(3) The gate plug of the DS pit is divided into four parts based on the existing nuclear power plant information, and each height is 1820 mm from the first to third stages and 1600 mm from the fourth stage from the operation floor.
(4) Presupposed specifications are a maximum lifting distance of about 33000 mm (from operation floor to pedestal floor), horizontal maximum working radius; about 2785 mm (up to reactor vessel inner wall).

1-2. Basic structure (1) Lifting mechanism is a tension truss crane, and fuel debris extraction part is a manipulator device and cutting equipment, etc. based on actual use in nuclear reactor facilities in foreign countries (2) Manipulator device structure Fuel debris The manipulator device used for the take-out device has a total of six-axis joints made of a metal body, and grips fuel debris with a chuck at the tip. The payload is about 90 kg and the maximum reach is about 1600 mm.
(3) Manipulator device mounting equipment

  The cutting equipment is a disk cutter, scissors, saw, core boring, etc. These can be automatically attached and detached by an attachment mechanism.

  Furthermore, a monitoring device such as ITV and LED lighting for the same are attached to the manipulator device, and remote monitoring control is possible.

1-3. The following devices are deployed as fuel debris retrieval devices.
(1) The cutting piece and cutting powder collecting device collects the cutting piece etc. in the configuration of cyclone and bag filter, blower, storage can storage device, lid clamp, and delivers the cutting piece etc. to the storage can set under the cyclone Cover when it is full.
(2) The cutting device cuts the surface of the debris with an end mill.
(3) The excavator excavates debris by core boring.
(4) The cutting device opens a hole in the debris by the excavator, and then inserts a disk cutter into the hole to cut the debris horizontally.
(5) The manipulator arm is operated when a tool such as shielding material adsorption and cutting is used.
(6) The water jet cutting machine cuts the object with water containing an abrasive.
(7) The self-propelled manipulator performs debris collection work outside the pedestal.

2. Reactor vessel flange lid The door that shuts off the atmosphere inside the RPV is mounted on the RPV flange portion, has no airtightness, and is closed when the slide shielding plate is retracted to the DS pit.

  3. The crane apparatus is composed of an elevating part and a wire tension monitoring part, and the rated hoisting load is about 50 ton and the approximate weight is about 80 ton.

  Hereinafter, the fuel debris extraction process will be described with reference to the flowcharts of FIGS. 3 to 7, the cross-sectional views of the reactors of FIGS. 2 and 8, and the drawings showing the shielding materials. 3 to 7, the main process (steps 101 to 140) is shown on the left side, and the subprocess (steps 201 to 231) consisting of a preparation process for the main process and a waste carry-out process is shown on the right side. Show.

  As shown in FIG. 3, in step 101, a work hole is drilled in the shield plug 36. Before that, there is a sub-process of steps 201-205.

  In step 201, the barrier 46 is installed. In step 202, the container temporary opening 42A is installed in the ceiling of the reactor building 42. In step 203, the horizontal rail 48A for the transfer container crane 48 is installed in the barrier 46. Is installed (see FIG. 2).

  In step 204, a slide shielding plate 56 provided with a slide shielding plate opening 57 through which a crane suspension or the like is passed in the center is installed on the operation floor 40. The slide shielding plate 56 is configured by attaching a roller to a shielding plate made of a radiation shielding material. As shown in FIG. 2, the slide shielding plate 56 has a standby position on the operation floor 40 and a position for closing the opening after removing the shield plug 36. It can be moved between.

  In the next step 205, as shown in FIG. 8, a drilling device 58 is installed on the shield plug 36, and in step 101 of the main process, the work hole 60 is drilled in the shield plug 36 by the drill of the drilling device 58. Drill in multiple places.

  As shown in FIG. 9, the working hole 60 drilled by the drilling device 58 has five central holes 60A in a cross shape at the center and eight outer holes 60B on the same circumference at the outer periphery. Each is formed. In FIG. 9, a slide shielding plate 56 in a standby state is shown to the right of the shield plug 36. The code | symbol 103 of FIG. 9 shows the operation control room for remotely controlling the said drilling apparatus 58, a crane, the below-mentioned various control apparatuses, and apparatus. The operation control chamber 103 is provided with an operation control device 104 (see FIG. 49C).

  Proceeding to step 102, the through-hole 62 penetrating from the central hole 60A to the upper side of the storage container head 14C, the pressure container head 20A, and the shroud head 26A is punched by the punching device 58. At this time, the heat insulating cover 55 of the pressure vessel head 20A is also perforated.

  The through-hole 62 is further drilled to the vicinity of the shroud head 26A of the stand pipe 30 above the shroud head 26A by further lowering the drill for drilling from the work hole 60 at the center of the shield plug 36.

  Meanwhile, in the sub-process, in step 206, the punching device 58 on the shield plug 36 is replaced with the decontamination device 64.

  Proceeding to step 103, as shown in FIG. 10, the decontamination water nozzle 65 of the decontamination apparatus 64 is inserted into the reactor cavity 38 from the working hole 60, and the tip (lower end) of the decontamination water nozzle 65. The decontamination water nozzle 65 is lowered through the through-hole 62, and the containment vessel head 14C, the heat retaining cover 55, and the pressure vessel head 20A are decontaminated. The inside and outside surfaces of the are decontaminated with decontamination water.

  Proceeding to step 104, as shown in FIG. 11, the high-pressure water pipe 66 in the decontamination apparatus 64 is passed through the shield plug 36, the containment vessel head 14 </ b> C, the heat insulation cover 55, and the pressure vessel head 20 </ b> A. The steam dryer 34 is passed through the high-pressure water pipe 66 and decontaminated water is jetted to decontaminate the steam dryer 34, and the high-pressure water pipe 66 is further connected to the lower steam / water separator 32 and the stand pipe 30. The structure of the core portion 24 is sequentially decontaminated by lowering and spraying decontamination water. At this time, the decontamination water extends to fuel debris which is presumed to have leaked to the lower part of the core 24 inside the shroud 26, and also to fuel debris which is considered to have been cured after being melted on the pedestal bed 16. Dyeing water is advantageous because it can suppress the temperature rise.

  In the sub-process, in step 207, the decontamination device 64 on the shield plug 36 is replaced with the shielding material filling device 68, and then the process proceeds to step 105 of the main process. In step 105, as shown in FIG. 12, the magnetic hollow small steel is formed in the ring shroud gap 70 between the outer periphery of the shroud 26 and the inner peripheral surface of the pressure vessel 20 by the shielding material dropping pipe 69A of the shielding material filling device 68. The shielding material B made of the sphere 73 is filled, and the shielding material A (the shroud head shielding layer 75A) made of the magnetic solid steel ball 72 is laid on the upper surface of the shroud head 26A (refer to FIG. 13 for details). In FIG. 13, reference numeral 76 denotes a jet pump, reference numeral 77 denotes a recirculation pump inlet pipe, and reference numeral 78 denotes a shielding material filling opening.

  The shielding material dropping pipe 69A is provided with a dropping cylinder inclined at the tip of the vertical portion, and the shielding material is uniformly dropped by rotating the dropping cylinder around the vertical portion.

  Here, with reference to FIG. 14A-14D, the shielding material which consists of said magnetic solid steel ball and a magnetic hollow steel ball is demonstrated.

  In this embodiment, as shown in Table 1, the shielding material A composed of a magnetic solid steel ball 72, the shielding material B composed of a magnetic hollow small steel ball 73 having an outer diameter of 50 mm, and a magnetic hollow large material having an outer diameter of 150 mm. The shielding material C is composed of a steel ball 74 and the shielding material D is composed of an ellipsoidal shielding bag 75 in which a shielding material A which is a magnetic solid steel ball 72 is packed in a cloth bag.

The shape, size, weight, volume, average density, and material of each of these four types of shielding materials A to D are as shown in Table 1.

  These shielding materials A to D are shown in FIGS. 14A and 14B. 14C and 14D show a state where the shielding material A is placed on the shielding material B, respectively. The diameter of the shielding material B is such that the plurality of shielding materials B are in contact with each other. The shielding material A stays in these gaps without dropping, and is selected so as to fill the gaps and enhance the radiation shielding effect.

  In the shielding materials A to D, the shielding material A is chromium-coated carbon steel or ferritic stainless steel, and the shielding materials B to D are all ferritic stainless steel. Is not limited to this, and may be any iron-based material that can be adsorbed by magnetic force. However, the chromium-coated carbon steel is almost the same as a so-called pachinko steel ball, and these have wear resistance and rust resistance. Ferritic stainless steel has high wear resistance and rust resistance. In an environment where rust is not particularly problematic, a magnetic steel ball made of a simple steel material may be used.

Next, Table 2 shows the relationship between the type of the shielding material A to the shielding material D filled or installed and the location.

  Here, the shielding material B made of the magnetic hollow small steel ball 73 is used for a gap on the outer periphery of the shroud where the jet pump is located (ring shroud gap) and a portion of the recirculation system piping. Since the filling place is narrow, the shielding material B made of a steel ball having a small outer diameter is used. The hollow material is used, for example, so that the shroud is within the limit value for plastic deformation inward due to the weight of the magnetic steel ball.

  The place where the shielding material C made of the magnetic hollow large steel ball 74 is used is used when the volume is relatively large and the limit value of plastic deformation is not large. The shielding material D composed of the shielding bag 75 is simply laid together with the bag at a location close to the horizontal plane and having a gap above, such as on the steam dryer 34 or the steam separator 32. Used when you can.

  As shown in FIG. 15, in step 105, the magnetic hollow small steel balls 73 are dropped and filled from the shielding material dropping pipe 69 </ b> A into the ring shroud gap 70 by the shielding material filling device 68 to fill the shroud shielding layer 71. Form.

  As shown in FIG. 47, the shielding material filling device 68 includes a shielding material dropping device 68A, a dropped tube storage device 68B, and a dropped tube insertion device 68C.

  The drop tube storage device 68B is configured to hold a plurality of shielding material drop tubes 69A vertically, and to advance and retract to the drop tube insertion device 68C by an endless track 69B.

  The drop tube insertion device 68C receives the shield material drop tubes 69A one by one from the drop tube storage device 68B, and sequentially pushes them into the holes penetrating the shield plug 36, as shown in FIG. The next shielding material dropping pipe 69A is connected to the upper end and pushed in to form a shielding material dropping pipe having a predetermined length.

  The shielding material dropping device 68A is brought close to the upper end of the shielding material dropping tube 69A that has been inserted and connected by the dropping tube insertion device 68C, and as shown in FIGS. 12, 15, and 16, the shielding material is applied from the upper end. I will continue to introduce.

  The shielding material dropping device 68A has a shielding material container 69C in which the shielding material is stored, and a shooting tube 69E that sequentially cuts out the shielding material in the shielding material container 69C by a feed screw 69D and drops it from the upper end of the shielding material dropping pipe 69A. And.

  Proceeding to step 106, a magnetic solid steel ball 72 is dropped on the upper surface of the shroud head 26A to form a shroud head shielding layer 75A.

  In step 107, the shielding bag 75 containing the magnetic solid steel balls 72 is dropped from the shielding material dropping pipe 69 to form an air / water separator shielding layer 75 </ b> B covering the upper surface of the air / water separator 32.

  In the next step 108, the shielding bag (shielding material D) 75 containing the magnetic solid steel ball 72 is dropped from the shielding material dropping pipe 69, and the steam dryer shielding layer 75C covering the upper surface of the steam dryer 34 is formed. To do.

  Proceeding to step 109, as shown in FIG. 16, a magnetic hollow large steel ball (shielding material C) 74 is dropped between the upper end of the containment vessel head 14C and the inner peripheral surface of the reactor cavity 38, and the containment vessel An upper end shielding layer 75D is formed.

  Proceeding to step 110, a shielding bag (shielding material D) 75 is dropped on the upper surface of the upper end shielding layer 75D of the storage container on the top surface of the top of the storage container head 14C to form the top shielding layer 75E.

  As shown in FIG. 17, in step 111 of the main process, the shield plug 36 is lifted by the overhead crane 44, and in the sub process, the slide shielding plate 56 is moved below the overhead crane 44 and lifted in step 208. The shield plug 36 is lowered onto the slide shielding plate 56.

  In the next step 209, the slide shielding plate 56 is lifted by the hanger 49 of the movable large crane (not shown), ie, below the temporary container opening 42 A of the reactor building 42 and the barrier opening 50 A of the barrier 46. The shield plug 36 is lifted by a large crane and carried out of the reactor building 42.

  As shown in FIG. 18, in the sub-process, in step 210, the upper structure removing manipulator 80 is installed on the slide shielding plate.

  As shown in FIGS. 19A and 19B, the upper structure removing manipulator 80 includes a rotary base 80A and a slider provided below the rotary base 80A so as to be movable within a certain range in the left-right direction in FIG. 19A. 80B, two arm support bases 80C provided on the lower side of the slider 80B, and an extendable arm 80D supported by the arm support bases 80C, respectively, and a storage container at the tip of the arm 80D A cutting jig 80E for the head can be attached. The slider 80B can be moved up and down within a certain range with respect to the base 81 by an elevating device 81A on a rotary base 80A installed on the support base 80F. The support base 80F is installed on the slide shielding plate 56.

  Note that the cutting jig 80E at the tip of the arm 80D can be replaced with a lifting electromagnet 80G or other tool shown in FIG. 19C.

  Returning to the main process, in step 112, the upper structure removing manipulator 80 is attracted by the lifting electromagnet 80G, and the shielding bag (shielding material D) 75 and magnetic hollow large steel on and near the cutting line of the cutting operation in the next process. The sphere 74 is removed from the containment container upper end shielding layer 75D.

  In step 113, as shown in FIG. 20, the outer periphery of the storage container head 14C is cut by the cutting jig 80E of the manipulator 80 for removing the upper structure, and the storage container head 14C is cut off.

  In step 114, the remaining shielding bag (shielding material D) 75 and the magnetic hollow large steel ball 74 on the cut-out container head 14 </ b> C are lifted and removed by the upper structure removing manipulator 80. In step 211 of the sub process, as shown in FIG. 21, the storage container head storage box 82 is installed on the slide shielding plate 56.

  Returning to the main process, in step 115, the cut container head 14 </ b> C is lifted by the overhead crane 44 as shown in FIG. 22. In step 212 of the sub-process, the slide shielding plate 56 is moved, and the suspended storage container head 14C is lowered. In step 213, the containment vessel head 14 </ b> C is moved under the hanging tool 49 of the large crane (see FIG. 23), lifted through the temporary container opening 42 </ b> A, and carried out of the reactor building 42.

  In step 214, the upper structure removal manipulator 80 is installed on the slide shielding plate 56.

  Returning to the main process, in step 116, the shielding bag (shielding material D) 75 is dropped on the heat retaining cover 55 by the lifting electromagnet 80G of the manipulator 80 for removing the upper structure to form the heat retaining cover shielding layer 75F.

  In step 117 of the main process, the duct connected to the heat insulation cover 55 is cut by the cutting jig 80E of the manipulator 80 for removing the upper structure (see FIG. 24).

  In step 215 of the sub-process, the manipulator 80 for removing the upper structure is replaced with the heat insulating cover storage box 84 and the manipulator 85 and moved above the heat insulating cover 55 (see FIG. 25), and in step 118 of the main process, FIG. As shown in the drawing, the thermal insulation cover 55 is lifted by the overhead crane 44 to a position where it is accommodated in the thermal insulation cover storage box 84.

  In step 216 of the sub-process, as shown in FIG. 27, the thermal insulation cover storage box 84 that accommodates the thermal insulation cover 55 that has been lifted is moved under the lifting tool 49 of the large crane, and passes through the temporary container opening 42A. It is lifted and carried out of the reactor building 42.

  Returning to the main process, as shown in FIG. 28, in step 119, a shielding bag (shielding material D) 75 is dropped on the pressure vessel head 20A to form a pre-lifting pressure vessel head shielding layer 75G. Then, the flange bolt and washer for connecting the pressure vessel head flange are cut by the cutting jig 80E of the manipulator 80 for removing the upper structure.

  Meanwhile, in the sub-process, in step 217, the pressure vessel head storage box 86 is installed on the slide shielding plate 56, and the process returns to the main process. In step 121, as shown in FIG. The head 20 </ b> A is lifted until it is accommodated in the pressure vessel head storage box 86. In step 218, the pressure vessel head storage box 86 storing the pressure vessel head 20A is moved under the hanging tool 49 of the large crane, and is carried out of the reactor building 42 by the large crane.

  In step 219, the steam dryer storage box 87 is installed on the slide shielding plate 56, and is moved directly above the steam dryer 34 as shown in FIG.

  In step 220 of the sub-process, the slide shielding plate 56 is moved, and in step 122 of the main process, the steam dryer 34 is removed (see FIG. 31), and then steam drying is performed by the overhead crane 44 as shown in FIG. 32A. The vessel 34 is lifted up to a position where it is accommodated in the vapor dryer storage box 87, and the raised vapor dryer 34 is lowered.

  In step 221 in the sub process, as shown in FIG. 32B, the slide shielding plate 56 on which the steam dryer 34 is placed is moved onto the DS pit 52.

  In step 222, as shown in FIG. 32C and FIG. 32D, in the DS pit 52 on the lower side of the operation floor 40, in the decontamination tank 52A installed, the steam dryer 34 is decontaminated with decontamination water, It is carried out of the reactor building 42 together with the steam dryer storage box 87 by a crane. In step 223, the upper structure removing manipulator 80 is installed on the slide shielding plate 56.

  In step 123 of the main process, the shroud head shielding layer 75A at the drilling position is removed, and the core through hole 90 is drilled in the shroud head (see FIG. 33). The shroud head shielding layer 75A is removed by being attracted by the lifting electromagnet 80G of the manipulator 80 for removing the upper structure.

  Proceeding to step 124, the core material is filled with the shielding material C made of the magnetic hollow steel ball 74 through the core through-hole 90, and the shielding bag (shielding material D) 75 containing the magnetic solid steel ball 72 is dropped. Thus, the core upper end surface shielding layer 75H is formed.

  In step 125, as shown in FIG. 34A, the shielding bag 75 constituting the shroud head shielding layer 75A is sucked and removed by the lifting electromagnet 80G of the upper structure removing manipulator 80, and in step 126, the upper structure removing manipulator 80G is used. The fixing bolt of the steam separator 32 to the pressure vessel 20 is removed by the manipulator 80.

  In step 224 of the sub-process, the steam / water separator storage box 91 is installed on the slide shielding plate 56 and moved to a position above the steam / water separator 32 as shown in FIG. 34B. Returning to the main process, in step 127, the overhead crane 44 lifts the steam / water separator 32 to a position where it is accommodated in the steam / water separator storage box 91 as shown in FIG. 35A, and this is stored in the steam / water separator. It is housed in a box 91 and moved to a hanging position by a large crane as shown in FIG. 35B.

  In step 225 of the sub-process, the steam-water separator 32 stored in the steam-water separator storage box 91 is decontaminated by being placed in a decontamination tank 52A under the operation floor 40, as shown in FIG. 36A. In 226, as shown in FIG. 36B, the decontaminated air / water separator 32 is lifted by the large crane together with the air / water separator storage box 91 and carried out of the reactor building 42.

  In step 227, as shown in FIG. 37A, preparation for fuel debris retrieval is performed. That is, a storage can stand 95 and a maintenance inspection table 96 are installed in the equipment storage pit 52, and a storage can rack 95A and a storage can transfer cart 95B are installed in the spent fuel pool 54, respectively. Further, in step 128 of the main process, a flange lid 94 that opens and closes the upper part of the core is installed at the attachment portion of the pressure vessel head 20A to the inner periphery of the containment vessel 14.

  Proceeding to step 228, the fuel debris retrieval device 100 is installed on the slide shielding plate 56, as shown in FIG. 37B.

  The flange lid 94 is configured by attaching a radiation shielding material, and closes the upper end opening of the pressure vessel 20 in a state shown by a solid line in FIGS. 37A and 37B, and opens the opening in a state shown by a chain line in FIGS. 37A and 37B. The operation of the overhead crane 44 and the manipulator 80 for removing the upper structure and the operation of the core portion 24 of the fuel debris extraction device 100 are made possible. FIG. 37C is a plan view showing the flange lid 94 and the fuel debris extraction device 100.

  The fuel debris retrieval device 100 includes a manipulator device 101 and a tension truss crane device 102.

  As shown in FIG. 48, the tension truss crane device 102 suspends the manipulator device 101 with a wire, but the tension truss is applied to prevent the manipulator device 101 from swinging.

  Further, the manipulator device 101 includes a turntable 101A suspended by a tension truss crane device 102, a cutting tool table 101B attached to the lower side of the turntable 101A, and a storage can 95C for storing the cut fuel debris. A storage can base 101C, a manipulator arm 101D, and a storage can lift 101E are provided.

  In FIG. 48, reference numeral 101F denotes a water jet water tank, and 101G denotes a filter device. A cutting tool 101H such as an end mill is attached to the tip of the manipulator arm 101D.

  The cutting tool base 101B is equipped with a cutter 101I and a water jet nozzle 101J as replacement tools for the tip of the manipulator arm 101D. These can be exchanged by operating the manipulator arm 101D.

  In addition to the above, the manipulator arm 101D can be replaced with a lifting electromagnet 101K shown in FIG. 49A or a core boring 101L shown in FIG. 49B.

  The fuel debris retrieval device 100 is remotely operated by an operation control device 104 shown in FIG. 49C. The operation control device 104 includes an operation / monitoring panel 104A, a control panel 104B, and a power panel 104C. The control panel 104B includes a plurality of servo controllers 104D and a power supply unit 104E, and sends control signals and power to the manipulator device 101 and the tension truss crane device 102 of the fuel debris extraction device 100. The upper structure removal manipulator 80 and the like are also remotely operated from the operation control room 103.

  Proceeding to step 129, as shown in FIGS. 38A and 38B, the flange lid 94 is opened, and the manipulator device 101 of the fuel debris retrieval device 100 is lowered. Until the next step 130, the transfer container 97 is prepared in the equipment storage pit 52 in the sub-step 228.

  Proceeding to step 130 of the main process, as shown in FIG. 39A, the fuel debris take-out device 100 adsorbs and removes the shroud shielding layer 71, and further cuts and lifts the in-furnace structure and the fuel debris 110 from above. This cutout approaches the pressure vessel lower mirror 20B shown in FIG. 39C from the state of FIG. 39B.

  In step 131, as shown in FIG. 39B, the suspended in-furnace structure and fuel debris 110 are placed in the storage can 95C and stored in the transfer container 97 of the storage can cradle 95 in the equipment storage pit 52.

  In sub-steps 229 and 230, the transfer container 97 is transferred to the spent fuel pool by the transfer container crane 48.

  In step 230 of the sub process, the lifted transfer container 97 is accommodated in the storage can rack 95 </ b> A of the spent fuel pool 54.

  In step 132, the shielding material dropping through-hole 111 is drilled in the outer peripheral portion of the pressure vessel lower mirror 20B (see FIG. 40). In step 133, as shown in FIG. And an integrated suspension 93A of the pressure vessel lower mirror 20B.

Proceeding to step 134, as shown in FIG. 42A, the shielding material is dropped from the shielding material dropping through-hole 111, and between the upper surface of the pressure vessel lower mirror 20B and the integral suspension 93A, the CRD changer 112, the pedestal floor A shielding material layer 75I is formed on 16. Specifically, from the through hole 111 for dropping the shielding material, a magnetic solid steel ball 72 (outer diameter: about 25 mm, density: 7.8 g · cm ³ ) or a shielding bag 75 containing the steel ball is placed around the CRD exchange device 112. And about 40 cm thick on the fuel debris 110 of the pedestal floor 16 to reduce the radiation to about 1/100. Alternatively, a magnetic hollow small steel ball 73 (outer diameter of about 50 mm, plate thickness of 3 mm, density is about 3 g / cm ³ heavier than water) collected from the gap of the jet pump 76 is thrown into a thickness of about 70 cm.

  In step 135, the flange lid 94 is removed, and the CRD integrated storage box 113 is installed at the upper end of the pressure vessel 20 from which the head has been removed.

  In the next step 136, as shown in FIG. 42B, when the pressure vessel lower mirror 20B and the CRD are lifted together through the container temporary opening 42A, which is a temporary lifting opening, and the wire lifting opening 50B, by a large crane wire. At the same time, the CRD integrated storage box 113 is lifted by the integrated lifting tool 93A.

  Meanwhile, in step 231 of the sub-process, the CRD integrated structure is moved together with the CRD integrated storage box 113 through the barrier opening 50A for lifting the ceiling of the reactor building 42 and the ceiling of the barrier 46 by the crane 49 of the large crane. Lift and carry out.

  42C to 42E show a process of removing the pressure vessel lower mirror 20B and the CRD integrally.

  In FIG. 42C, reference numeral 115 denotes a CRD seismic support, and 116 denotes a CRD exchange path.

  From the through hole 111, the laser cutter 117 in the manipulator device 101 is inserted, and the CRD seismic support 115, the in-core monitor cable, and the like are cut.

  FIG. 42D shows a state where the circumference of the pressure vessel lower mirror 20B is cut by the cutter 101I of the manipulator device 101. FIG. 42E shows a state immediately before the hook of the integral suspension 93A is connected to the wire 93B of the mobile large crane and lifted.

  The CRD integrated storage box 113 is placed on the RPV flange part in the middle of being suspended together with the integrated suspension 93A by a large crane.

  Proceeding to step 137 of the main process, the shielding material on the CRD exchanging device 112 is removed by the fuel debris removing device 100, and the fuel debris 110 and the CRD exchanging device 112 are cut and lifted (see FIG. 43).

  Proceeding to step 138 of the main process, the shielding material layer on the pedestal floor 16 is removed, and the fuel debris 110 is cut and lifted (see FIG. 44).

  In step 139, as shown in FIG. 45, the self-propelled manipulator 114 cuts and removes the fuel debris 110 flowing out from the pedestal portion inspection passage and the shielding material thereon.

  Finally, as shown in FIG. 46, the flange lid 94 is closed, and further, the center portion of the operation floor 40 is closed by the slide shielding plate 56, the temporary opening above the operation floor 40 is also closed, and all the processes are completed. .

DESCRIPTION OF SYMBOLS 10 ... Reactor 12 ... Living body shielding wall 14 ... Reactor containment vessel (containment vessel)
DESCRIPTION OF SYMBOLS 14A ... Containment vessel spherical shell part 14B ... Containment vessel cylindrical part 14C ... Containment vessel head 16 ... Pedestal floor 18 ... Cylindrical biological shield 20 ... Reactor pressure vessel (pressure vessel)
20A ... Pressure vessel head 20B ... Pressure vessel lower mirror 22 ... Control rod drive mechanism 24 ... Core section 26 ... Shroud 26A ... Shroud head 28 ... Control rod guide tube 30 ... Stand pipe 32 ... Air-water separator 34 ... Steam dryer 36 ... Shield plug 38 ... Reactor cavity 40 ... Operating floor (operating floor)
42 ... Reactor building 42A ... Container temporary opening 42B, 50C ... Open / close panel 44 ... Overhead crane 46 ... Barrier 47 ... Perimeter shield 48 ... Transfer container crane 48A ... Rail 49 ... Suspension tool 50A ... Barrier opening 50B ... Wire lifting opening 52 ... Equipment storage pit (DS pit)
52A ... decontamination tank 54 ... spent fuel pool 55 ... heat insulation cover 56 ... slide shielding plate 57 ... slide shielding plate opening 58 ... punching device 60 ... work hole 60A ... central hole 60B ... outer hole 62 ... through hole 64 Decontamination device 65 Decontamination water nozzle 66 High-pressure water pipe 68 Shielding material filling device 68A ... Shielding material dropping device 68B ... Dropping tube storage device 68C ... Dropping tube insertion device 69A ... Shielding material dropping tube 69B ... Endless track 69C ... Shielding material container 69D ... feed screw 69E ... chute tube 70 ... ring shroud gap 71 ... shroud shielding layer 72 ... magnetic solid steel ball 73 ... magnetic hollow small steel ball 74 ... magnetic hollow large steel ball 75 ... shielding bag 75A ... shroud head Shielding layer 75B ... Air-water separator shielding layer 75C ... Steam dryer shielding layer 75D ... Container upper end shielding layer 75E ... Top shielding layer 75F ... Heat cover shielding layer 75G ... Pressure vessel head shielding layer before lifting 75H ... Core upper end shielding layer 75I ... Shielding material layer 76 ... Jet pump 77 ... Recirculation pump inlet piping 78 ... Shielding material filling opening 80 ... Superstructure removal Manipulator 80A ... rotating table 80B ... slider 80C ... arm support table 80D ... arm 80E ... cutting jig 80F ... rotating support table 80G ... lifting electromagnet 81 ... base 81A ... lifting device 82 ... storage container head storage box 84 ... heat insulation cover Storage box 85 ... Manipulator 86 ... Pressure vessel head storage box 87 ... Steam dryer storage box 90 ... Core through hole 91 ... Steam-water separator storage box 93A ... Integrated suspension 94 ... Flange lid 95 ... Storage can stand 95A ... Storage Can rack 95B ... Storage can transfer cart 95C ... Storage can 96 ... Maintenance inspection table 97 ... Transfer container 100 ... Fuel Debris extraction device 101 ... Manipulator device 101A ... Rotation table 101B ... Cutting tool table 101C ... Storage can table 101D ... Manipulator arm 101E ... Storage can lift 101F ... Water tank 101G ... Filter device 101H ... Cutting tool 101I ... Cutter 101J ... Water jet Nozzle 101K ... Lifting electromagnet 101L ... Core boring 102 ... Tension truss crane device 103 ... Operation control room 104 ... Operation control device 104A ... Operation / monitoring panel 104B ... Control panel 104C ... Power supply panel 104D ... Servo controller 104E ... Power supply unit 110 ... Fuel debris 111 ... Through hole for dropping shielding material 112 ... CRD exchange device 113 ... CRD integrated storage box 114 ... Self-propelled manipulator 115 ... CRD earthquake resistant support 116 ... CRD exchange passage 117 ... Zakatta

Claims (12)

A pressure vessel for storing the reactor core, a containment vessel for storing the pressure vessel, and a reactor cavity surrounding the containment vessel, and a shield plug covering an upper portion of the containment vessel head at the upper end of the containment vessel; A method for removing fuel debris accumulated in a lower portion of the pressure vessel and a bottom portion of the containment vessel in a nuclear reactor, the reactor containment vessel, the reactor pressure vessel, and a reactor disposed inside thereof A fuel debris retrieval method in which an internal structure and fuel debris leaked into and out of the reactor pressure vessel or pedestal are drilled and cut, lifted to a height above the reactor operating floor, and removed.
Prior to the drilling or cutting step, a magnetic solid steel ball, a magnetic ball is formed on the upper end surface of at least one of the reactor containment vessel, the reactor pressure vessel, and the reactor internal structure in the space above the object to be drilled or cut. Shielding material comprising any one of a hollow steel ball, a large-diameter magnetic hollow steel ball whose diameter is 2 to 4 times the diameter of the magnetic hollow steel ball, and an ellipsoidal shielding bag comprising a cloth bag filled with the magnetic solid steel ball Forming a shielding layer by placing
A step of forming a working space for drilling or cutting by adsorbing the shielding material at an upper position of a drilling or cutting scheduled portion in the object by an electromagnet and lifting and separating from the shielding layer;
A work step of drilling or cutting the object from above through the formed work space;
Lifting and removing a section of the object that has been drilled or cut by the drilling; and
Filling an annular space surrounding the side surface of the object with the shielding material to form an annular shielding layer;
After completion of the cutting operation of the object, a step of adsorbing and lifting the shielding material constituting the annular shielding layer with an electromagnet, and taking out,
Having
The step of forming the shielding layer includes the step of dropping the magnetic hollow large steel ball to form the containment vessel upper end portion shielding layer between the upper end portion of the containment vessel and the inner peripheral surface of the reactor cavity, and A step of forming a top shielding layer by simply laying a shielding material composed of the ellipsoidal shielding bag together with the bag on the upper end shielding layer of the storage container;
The step of forming the annular shielding layer is performed by filling the shroud head with a magnetic hollow small steel ball as a shielding material so that the ring shroud gap with a narrow filling place is within a limit value where the shroud is plastically deformed inward by weight. Forming a shielding layer,
A fuel debris retrieval method characterized by the above. In claim 1,
A fuel debris comprising the step of decontaminating the object and the reactor structure below the object by spraying decontamination water from the hole formed by the drilling after the object is drilled. Extraction method. In claim 1 or 2,
The diameter of the magnetic hollow steel ball is such that when a plurality of magnetic hollow steel balls are in contact with each other, the magnetic solid steel ball remains in the gap without dropping. Extraction method. A pressure vessel for storing the reactor core, a containment vessel for storing the pressure vessel, and a reactor cavity surrounding the containment vessel, and a shield plug covering an upper portion of the containment vessel head at the upper end of the containment vessel; A method for removing fuel debris accumulated in a lower part of the pressure vessel and a bottom part of the containment vessel in a nuclear reactor,
Drilling a plurality of working holes penetrating from the upper side to the lower side of the shield plug;
The upper part of the core part from the working hole to at least the upper end of the containment vessel and the upper end of the pressure vessel and the upper end of the pressure vessel to the upper position of the shroud head at the upper end of the shroud. Drilling through-holes in the structure from above;
A decontamination water nozzle is projected through the working hole to the lower side of the shield plug, further through the through hole, into the containment vessel and the pressure vessel to spray decontamination water, and at least An upper decontamination step for decontaminating the lower surface of the shield plug, the inner peripheral surface of the upper part of the reactor cavity, the inner and outer surfaces of the containment vessel head, and the inner and outer surfaces of the pressure vessel head;
A shield material dropping pipe is suspended from the through hole, a shield material made of a magnetic steel ball is dropped from the lower end, and a ring shroud gap between the outer peripheral surface of the shroud and the inner peripheral surface of the pressure vessel is filled, And forming a shroud head shielding layer covering the upper surface of the shroud head;
Dropping a shielding bag containing a plurality of magnetic steel balls through the through-hole, and forming an upper shielding layer over the upper surface of the upper structure of the core portion above the shroud head; and
Through the through hole, a shielding material made of a magnetic steel ball is dropped between the upper end portion of the pressure vessel and the inner peripheral surface of the reactor cavity around it, and the upper end portion of the pressure vessel excluding the top portion of the pressure vessel head Forming a pressure vessel upper end shielding layer for shielding,
Dropping a shielding bag similar to the above onto the top of the pressure vessel head and the upper surface of the pressure vessel upper end shielding layer to shield the top and the upper surface of the shielding material to form a top shielding layer;
Lifting and removing the shield plug;
A storage container head cutting step of cutting the storage container head by a manipulator;
Removing the shielding bag and the pressure vessel upper end shielding layer on the cutting line of the cutting operation before the storage container head cutting step;
Removing the shielding bag and the pressure vessel upper end shielding layer on the cut storage container head after the storage container head cutting step;
A step of removing the cut-out containment head;
A step of dropping a shielding bag similar to the above onto a heat insulation cover located between the storage container head and the pressure container head after the removing step to form a heat insulation cover shielding layer;
A heat insulation cover removing step of lifting and removing the heat insulation cover after cutting the duct connected to the heat insulation cover;
A flange bolt washer cutting step of cutting a flange bolt washer connected to the inner periphery of the containment vessel of a flange provided on the upper outer periphery of the pressure vessel head;
A pressure vessel head removing step of lifting and removing the pressure vessel head;
Forming a core through hole in the shroud head through the through hole and further through the shroud head shielding layer;
A step of filling a shield made of a large number of magnetic steel balls into the core through the core through hole and dropping a shielding bag similar to the above to form a core upper end surface shielding layer on the core upper end surface When,
Removing the shroud head shielding layer;
The fuel debris and the reactor internal structure are cut out from above, and the fuel debris retrieval device having a manipulator that adsorbs the shield from above is used to adsorb the shielding material at the top in the reactor core, thereby Cutting the object and fuel debris from the upper side, lifting the adsorbed shielding material, the cut fuel debris, and the in-furnace structure to remove,
A fuel debris retrieval method comprising: In claim 4,
After the upper decontamination step, a high-pressure water pipe is passed through the pressure vessel head from the through hole and passed to the steam dryer below the decontamination water to decontaminate the vapor dryer;
A fuel debris retrieval method comprising: In claim 5,
After the step of forming the upper shielding layer, a step of dropping a plurality of shielding bags similar to the above through the working hole to form a steam dryer shielding layer that covers and shields the upper surface of the steam dryer. ,
A fuel debris retrieval method comprising: In any one of Claims 4 thru | or 6.
After the step of removing the shroud head,
Removing a fixing bolt to the pressure vessel of the steam separator;
Lifting and removing the steam separator;
A fuel debris retrieval method comprising: In any of claims 4 to 7,
After the step of removing the shield plug, the operating floor is movable between a shielding position covering the opening from which the shield plug has been removed and a retracted position retracted on the operating floor, and an upper structure removing manipulator is provided. Installing a detachable slide shield plate; and
A fuel debris retrieval method comprising: Oite to claim 8,
Installing a flange lid with a shielding material on the mounting seat on the inner periphery of the containment vessel to which the flange of the pressure vessel head was fixed;
A fuel debris retrieval method comprising: In claim 9,
A crane device that suspends the manipulator and lifts the manipulator; and a carriage that supports the crane device and is movable between a retracted position on the operating floor and a work position above the flange lid. A step of installing a fuel debris retrieval device comprising:
Moving the carriage to the working position, opening the flange lid and lowering the fuel debris retrieval device;
A fuel debris retrieval method comprising: In any one of Claims 4 thru | or 10.
A magnetic debris retrieval method, characterized in that the magnetic steel balls forming the top shielding layer are hollow ferromagnetic stainless steel balls, and the total weight thereof is less than the plastic deformation limit value of the pressure vessel head. In any one of Claims 4 thru | or 10.
The fuel debris retrieval method, wherein the manipulator includes a magnetic adsorption unit that adsorbs a magnetic steel ball, and the magnetic adsorption unit adsorbs and lifts the shielding material and the shielding bag.