JP6439933B2 - Fuel debris recovery ventilation system and fuel debris recovery ventilation method - Google Patents

Description

  The present invention relates to a ventilation system and a ventilation method when recovering fuel debris solidified in a reactor pressure vessel and a reactor containment vessel.

  “Fuel debris” is a nuclear fuel material in which nuclear reactor fuel debris is formed in the nuclear reactor. The nuclear fuel material melts due to loss of coolant and is cooled and solidified along with the reactor structural materials and control rods. is there. When fuel debris is generated, it is considered that the fuel debris exists in a reactor pressure vessel (RPV) or a primary containment vessel (PCV).

  When decommissioning a nuclear reactor that generates fuel debris, it is important to collect the fuel debris in advance from the viewpoint of preventing radioactive contamination of the external environment.

  For example, in the nuclear fuel material carry-out method described in Patent Document 1, a work house is installed on the operation floor of the reactor building, a preparation house is installed on the work house, and a boring device having a cutting device in the work house is provided. It is installed. Large openings are formed in the operation floor and the floor and ceiling of each house, and various devices and recovered fuel debris are transferred through these openings.

  Further, in the nuclear fuel material extraction method described in Patent Document 2, an access passage is formed from the side of the biological shield surrounding the reactor containment vessel in the reactor building, and the radiation shielding chamber communicating with the access passage is often used. A joint access device is arranged, and fuel debris collection work is performed by the multi-joint access device.

JP 2013-19875 Japanese Unexamined Patent Publication No. 2014-070946

  In the method described in Patent Document 1 described above, since the nuclear fuel material in the core is cut by the cutting device, the shredded fuel debris is scattered or dropped, and the cooling water for cooling the fuel debris and the internal gas are used. There is a possibility of contamination. Since the work house and the preparation house communicate with the reactor pressure vessel through the opening, each house is also contaminated at the same level as the inside of the reactor pressure vessel.

  In the method described in Patent Document 2, a pair of doors are provided in the radiation shielding chamber. When one of the doors is opened, the other is closed to maintain airtightness. When there are cables for supplying power, piping for supplying hydraulic pressure, rails used for moving the cutting device, etc., the doors must always be opened. If so, the radiation shielding chamber will be contaminated at the same level as in the reactor containment.

  It is necessary to ventilate the building when performing operations such as cutting and collecting fuel debris, but a filter is provided for the exhaust from the building to prevent the radioactive material from being released to the outside. The apparatus which removes is provided in multiple stages. In order to efficiently remove radioactive substances by using these filters and radioactive substance removing devices, it is desired to suppress the displacement.

  However, as in Patent Documents 1 and 2, the work house, the preparation house, and the radiation shielding chamber communicate with each other when cutting and collecting the fuel debris, and each of these chambers is substantially the same as the reactor pressure vessel and the reactor containment vessel. The problem is that if the level is contaminated, the contaminated area widens.

  The present invention has been devised in view of such problems, and provides a ventilation system for fuel debris recovery and a ventilation method for fuel debris recovery that can more efficiently remove radioactive substances in ventilation performed during fuel debris recovery work. The purpose is to provide.

  In order to achieve the above object, a first invention is a fuel debris recovery ventilation system for recovering fuel debris solidified in a reactor pressure vessel or a reactor containment vessel, wherein the reactor containment A shielding chamber communicating with the inside of the container, a recovery means that approaches the fuel debris from the shielding chamber, and performs a recovery operation of the fuel debris; while partially allowing passage of the recovery means, the shielding chamber and the Partitioning means for partitioning between the reactor containment vessel, gas supply means for supplying gas from outside into the shielding chamber, and storing the reactor at a flow rate higher than the flow rate of gas supplied by the gas supply means An exhaust amount adjusting means for exhausting from the container, and a radioactive substance removing means for performing a removal process on the radioactive substance in the exhaust.

  In a fuel debris recovery ventilation system according to a second aspect of the present invention, in the first aspect, the shielding chamber is an upper shielding chamber installed above the reactor pressure vessel, and the recovery means includes the fuel debris A working unit that performs a recovery operation on the fuel and a cargo handling unit that transports the fuel debris into the upper shielding chamber, and the partition means is located on the reactor containment vessel side in the upper shielding chamber. And an airtight sheet that divides the cargo handling part side and has an introduction part that is temporarily opened to allow passage of the cargo handling part.

  According to a third aspect of the present invention, there is provided a fuel debris recovery ventilation system according to the first or second aspect, wherein the periphery of the opening communicates between the shielding chamber and a reactor well formed above the reactor pressure vessel. And a refrigerant injection means for injecting a refrigerant into the reactor well.

  In the fuel debris recovery ventilation system according to a fourth aspect of the present invention, in the first aspect, the reactor containment vessel is surrounded by a biological shielding wall, and the side surface of the nuclear reactor containment vessel and the side surface of the biological shielding wall Through holes are formed at corresponding positions, and the shielding chamber is a side shielding chamber that is in close contact with the side surface of the biological shielding wall and covers the through hole, and the collecting means is the side shielding chamber. The fuel debris is collected through the through-hole, and the partition means is a divided door that can be opened and closed independently by each of the divided parts, and the divided door is a main body of the manipulator A first door that opens and closes a region through which the portion passes; and a second door that opens and closes a region through which the connecting member connected to the manipulator passes.

  The fuel debris recovery ventilation system according to a fifth aspect of the present invention is the fuel debris recovery ventilation system according to any one of the first to fourth aspects, further comprising an auxiliary shielding chamber communicated with the shielding chamber via the communicating portion, and opening / closing of the communicating portion. And an opening / closing means for performing.

  6th invention is a ventilation method at the time of fuel debris collection at the time of recovering the fuel debris solidified in a reactor pressure vessel or a reactor containment vessel, and provides a shielding room connected with the inside of the reactor containment vessel A step of recovering the fuel debris from the shielding chamber and performing a recovery operation of the fuel debris, and partially allowing passage of a member accompanying the recovery operation in the recovery step. A step of providing partition means for partitioning between the reactor containment vessel and the reactor containment vessel, a gas supply step of supplying a gas from the outside into the shielding chamber, and a flow rate higher than a flow rate of the gas supplied in the gas supply step And an exhaust amount adjusting step for exhausting from the reactor containment vessel, and a radioactive substance removing step for performing a removal process on the radioactive substance in the exhaust.

  According to the present invention using the above means, in the ventilation performed during the fuel debris recovery operation, the recovery chamber is allowed to be separated from the reactor containment vessel while allowing the recovery operation, thereby limiting the region with a high contamination level. Since the amount can be suppressed, the radioactive substance can be removed more efficiently.

It is a schematic block diagram in the reactor building before collect | recovering fuel debris. It is a schematic block diagram in the reactor building at the time of fuel debris collection | recovery. It is an enlarged view of a top access collection device. It is a perspective view which shows the manipulator unit for work, and an airtight sheet | seat. (A) Enlarged view of the side access collection device, (b) Front view when the divided door is fully opened, and (c) Front view when the lower door of the divided door is closed. It is a schematic block diagram which shows the ventilation structure in a reactor building.

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

  The nuclear reactor shown in FIG. 1 is a boiling water reactor (BWR: Boiling Water Reactor). The reactor pressure vessel 11 is a vessel for housing a core, and is a steel vessel that can withstand high temperatures and high pressures. The reactor containment vessel 12 is a vessel for storing main equipment such as the reactor pressure vessel 11 and is a steel or concrete vessel having high hermeticity and pressure resistance. The reactor pressure vessel 11 and the reactor containment vessel 12 are stored in a concrete reactor building 1. The reactor building 1 has a role of preventing leakage of radioactive materials in the event of a nuclear reactor accident. The fuel pellet, fuel cladding tube, reactor pressure vessel 11, reactor containment vessel 12, and reactor building 1 form a five-layer barrier. In the reactor building 1, the concrete wall that surrounds the outer periphery of the reactor containment vessel 12 is called a biological shielding wall 13.

  A plurality of partitioned spaces are formed in the reactor building 1, and in this partitioned space, a pressure suppression pool 14 disposed in a ring shape below the reactor containment vessel 12, equipment is temporarily placed during maintenance or the like. An equipment temporary pool 15, a fuel storage pool 16 for storing spent fuel, and the like are arranged. In FIG. 1, the details of the control rod and the cooling system are omitted. Further, the reactor building 1 is not limited to the illustrated configuration.

  A cylindrical pedestal 17 that supports the reactor pressure vessel 11 is formed at the bottom of the reactor containment vessel 12, and a control rod drive mechanism (not shown) is disposed inside the pedestal 17. . A cylindrical γ-ray shield 18 surrounding the reactor pressure vessel 11 is disposed on the pedestal 17. A pedestal opening 17a for accessing the internal control rod drive mechanism is formed on the side surface of the pedestal 17.

  A dry well head 12 a that seals the reactor containment vessel 12 in a hermetically sealed state is disposed on the top of the reactor containment vessel 12. In addition, an upper lid 11 a that seals the reactor pressure vessel 11 in a sealed state is disposed at the top of the reactor pressure vessel 11.

  The vertical hole formed above the dry well head 12 a is called a reactor well 19 and is sealed by a shielding plug 20. The shielding plug 20 is composed of, for example, three discs made of concrete. The uppermost shielding plug 20a has the largest diameter, the intermediate shielding plug 20b has a smaller diameter than the uppermost shielding plug 20a, and the lowermost shielding plug 20c has a smaller diameter than the intermediate shielding plug 20b. It is formed as follows. In addition, since these shielding plugs 20 are heavy objects, they may be divided into a plurality in the width direction.

  On the upper surfaces of the shielding plug 20, the equipment temporary storage pool 15, and the fuel storage pool 16, an operation floor 1 a that is a work floor is formed. In addition, an overhead crane 1b for equipment transportation is installed in the upper part of the reactor building 1.

  When an accident such as core melting occurs, the reactor nuclear fuel melts due to the loss of the coolant and is cooled and solidified together with the reactor structural material, control rods, etc., and may become fuel debris. For example, FIG. 2 shows a case where the fuel debris X1 exists at the bottom of the reactor pressure vessel 11 and the fuel debris X2 exists at the bottom of the reactor containment vessel 12. As described above, when decommissioning the reactor in which the fuel debris X1 and X2 is generated, it is important to collect the fuel debris X1 and X2 in advance from the viewpoint of preventing radioactive contamination of the external environment. It is.

  In the present embodiment, as shown in FIG. 2, as a device (recovery means) for recovering these fuel debris X1, X2, the fuel debris X1 at the bottom of the reactor pressure vessel 11 is recovered from above the reactor pressure vessel 11. And a side access recovery device 60 that recovers fuel debris X2 at the bottom of the reactor containment vessel 12 from the side of the reactor containment vessel 12 through the living body shielding wall 13. The “recovery” of the fuel debris X1 and X2 may include all operations for fuel debris such as cutting, crushing, and pulverization in addition to the recovery operation for the fuel debris X1 and X2.

  First, the top access collection device 30 will be described.

  As shown in FIGS. 2 and 3, the top access recovery device 30 mainly includes a shielding port 31, an upper shielding chamber 32, an upper auxiliary shielding chamber 33, a working manipulator unit 34 (working unit), an airtight sheet 35 (partitioning means), It has a manipulator unit 36 for cargo handling (a cargo handling part).

  Specifically, when the top access collection device 30 is installed on the operation floor 1a, a circular upper opening 40 that penetrates the shielding plug 20 is formed, and a shielding port 31 is provided at the periphery of the upper opening 40. Yes. The shielding port 31 is provided with an opening / closing door 41 that opens and closes the upper opening 40. The dry well head 12a, the upper lid 11a, and the like are removed to secure an access route to the fuel debris X1.

  The upper shielding chamber 32 is installed so as to cover the upper side of the shielding port 31. Further, an upper auxiliary shielding chamber 33 is installed adjacent to the upper shielding chamber 32 and above the equipment temporary pool 15. In the upper shielding chamber 32 and the upper auxiliary shielding chamber 33, a communication opening 42 (communication portion) that communicates between the two chambers is formed on the walls that are in contact with each other, and the communication opening 42 is provided with the communication opening 42. Since the shielding door 43 (opening / closing means) that opens and closes is provided, diffusion of contamination to the upper auxiliary shielding chamber 33 is prevented. The walls and ceilings of the open / close door 41, the shielding door 43, the upper shielding chamber 32, and the upper auxiliary shielding chamber 33 are each composed of a shielding material, and are configured so that radiation and radioactive substances do not leak to the outside.

  A work manipulator unit 34, an airtight sheet 35, and a cargo handling manipulator unit 36 are disposed in the upper shielding chamber 32.

  As shown in FIG. 4, the working manipulator unit 34 includes an upper platform 44, a lower platform 45, and a manipulator arm 46.

  The upper platform 44 has two upper and lower annular bodies 44a and 44b positioned on the same axis and connected via a plurality of ribs 44c. The upper annular body 44a has an annular shape smaller than the lower annular body 44b, and a plurality of lifting mechanisms 47 (three in FIG. 4) for driving the wire 47a or the chain to move up and down are provided on the lower surface of the upper annular body 44a. It has been.

  The lower platform 45 is a substantially annular steel body that can flow through the inner circumferential circle of the lower annular body 44b and the upper opening 40. The lower platform 45 is suspended from the lower end of a wire 47a or chain extending from the lifting mechanism 47, and can move up and down between the upper shielding chamber 32 and the reactor pressure vessel 11.

  The manipulator arm 46 is an articulated arm, and is provided at two locations on the inner peripheral surface of the lower platform 45 in FIG. Each manipulator arm 46 performs a recovery operation such as cutting of the fuel debris X1 by remote control. An arbitrary processing tool 46 a (laser cutting machine, cutter, drill, shovel, etc.) is connected to the tip of the manipulator arm 46. The processing tool 46a can be switched by a robot or the like (not shown) arranged in the shielding chamber 3.

  The work manipulator unit 34 is covered with an airtight sheet 35. Specifically, the airtight sheet 35 has a hat shape along the outer shape of the upper platform 44 of the work manipulator unit 34, and defines a space between the reactor pressure vessel 11 side and the cargo handling manipulator unit 36 side in the upper shielding chamber 32. doing. A recovery container introducing portion 48 through which a recovery container 54 described later can pass is formed at the center of the upper surface of the airtight sheet 35. The collection container introduction portion 48 is provided with a so-called chrysanthemum cut in a circular shape radially from the center. The plurality of tongue pieces 48a formed by the cuts have a substantially triangular shape whose tip side can swing up and down. When the collection container 54 is pushed into the collection container introduction part 48, each tongue piece 48a has flexibility, so that the collection container 54 is allowed to pass, and after passing through the collection container 54, the original shape is obtained. The closed state is left while leaving a region through which the return wire or chain passes. The material of the airtight sheet 35 may be any radiation-resistant material that is flexible and does not transmit radioactive materials. For example, ethylene, propylene, diene rubber (EPDM rubber), nylon, or the like is preferable.

  Further, the cargo handling manipulator unit 36 is provided so as to surround the work manipulator unit 34, for example. The manipulator unit 36 for cargo handling is, for example, a portal gantry crane, and includes a pair of leg portions 50, a beam 51 spanned between the leg portions 50, and a plurality of movably arranged on the beam 51. And a trolley 52. A manipulator arm 53 and a collection container 54 are connected to the trolley 52. Similarly to the manipulator arm of the work manipulator unit 34, an arbitrary processing tool can be attached to and detached from the manipulator arm 53. The collection container 54 is a container that can store a cut section of the fuel debris X1, and is connected to the trolley 52 through a hoist, for example, and is configured to be able to be raised and lowered by the hoist.

  The top access recovery device 30 configured as described above performs cutting, crushing, pulverization, and the like of the fuel debris X1 by the manipulator arm 46 provided on the lower platform 45 of the working manipulator unit 34 when the fuel debris X1 is recovered. . On the other hand, the manipulator unit 36 for cargo handling lowers the recovery container 54 to the bottom of the reactor pressure vessel 11 through the recovery container introduction part 48 of the airtight sheet 35. Then, the manipulator arm 46 stores the section of the fuel debris X1 in the collection container 54. The collection container 54 in which the fuel debris X1 is accumulated rises and is returned again into the upper shielding chamber 32 through the collection container introduction part 48 of the airtight sheet 35. The section of the fuel debris X1 moved to the upper shielding chamber 32 is sealed in a container such as a canister and transferred to the upper auxiliary shielding chamber 33 or the like by the manipulator arm 53 of the manipulator unit 36 for cargo handling or other robot (not shown). The

  Most of the airtight sheet 35 is partitioned from the reactor containment vessel 12 side in the upper shielding chamber 32 except for the recovery container introducing portion 48, and the recovery container introducing portion 48 is also temporarily attached when the recovery container passes. Since it is only opened, the inflow of radioactive material from the reactor containment vessel 12 to the upper shielding chamber 32 is greatly limited. Further, since the upper shielding chamber 32 and the upper auxiliary shielding chamber 33 are closed by the shielding door 43 except when necessary, the inflow of radioactive material from the upper shielding chamber 32 to the upper auxiliary shielding chamber 33 is further restricted. Will be.

  The manipulator for cargo handling may be a simple jib crane as long as handling of the collection container 54 is possible.

  A plurality of water sprays 55 (refrigerating means) are provided below the periphery of the upper opening 40 that communicates between the upper shielding chamber 32 and the reactor well 19. The water spray 55 is a so-called dry mist nozzle, and injects water as a coolant downward in the reactor well 19. In this way, the water sprayed by the water spray 55 provided around the upper opening 40 cools the contaminated air that has been warmed and rises, thereby forming a downward flow (the white arrow in FIG. 3). Contamination expansion to the upper shielding chamber 32 can be further prevented.

  Next, the side access collection device 60 will be described.

  As shown in FIG. 5A, the side access collection device 60 mainly includes a side shielding chamber 61, an airtight cylinder 62, a side auxiliary shielding chamber 63, and a manipulator unit 64.

  Specifically, when the side access collection device 60 is disposed on the side of the reactor containment vessel 12 through the living body shielding wall 13, the side access recovery device 60 and the reactor containment vessel 12 pass through the biological shielding wall 13. A side opening 71 (through hole) is formed, and the side shielding chamber 61 is disposed so as to cover the opening of the through passage 70.

  The side shielding chamber 61 is in close contact with the living body shielding wall 13 via, for example, an inflatable sealing material 61a. The inflatable sealing material 61a is obtained by inflating a low-pressure air into a tube-shaped rubber seal. Such an inflatable sealing material 61a has already been sufficiently used as a sealing material in the fields of aircraft and nuclear equipment, and can seal the space between the side shielding chamber 61 and the biological shielding wall 13 in an airtight manner. . The sealing material is not limited to the inflatable sealing material 61a.

  On the other hand, a gap Δg of about several centimeters exists between the biological shielding wall 13 and the reactor containment vessel 12. Therefore, even if the space between the side shielding chamber 61 and the biological shielding wall 13 is sealed, if the side opening 71 is formed in the reactor containment vessel 12, the inside of the reactor containment vessel 12 and the gap Δg communicate with each other. The airtightness cannot be maintained.

  Therefore, in this embodiment, the airtight cylinder 62 is inserted from the side shielding chamber 61 into the through passage 70, and the end of the airtight cylinder 62 is the side surface of the reactor containment vessel 12 and the peripheral edge of the side opening 71. It is in close contact. Note that the close contact portion between the hermetic cylinder 62 and the reactor containment vessel 12 is also sealed by the inflatable sealing material 62a. By such a seal, the inside of the reactor containment vessel 12 and the inside of the side shielding chamber 61 are communicated using the airtight cylinder 62 while maintaining airtightness. Alternatively, it is possible to maintain airtightness by putting an inflatable seal directly in the gap Δg.

  In the side shielding chamber 61, the wall facing the airtight cylinder 62 is in contact with the side auxiliary shielding chamber 63. In the side shielding chamber 61 and the side auxiliary shielding chamber 63, a communication opening 72 (communication portion) that communicates the two chambers is formed on a wall that is in contact with each other.

  In the manipulator unit 64, a rail 64b that supports the manipulator arm 64a is disposed from the side auxiliary shielding chamber 63 through the side shielding chamber 61 and the airtight tube 62 to the pedestal opening 17a. The manipulator arm 64a is movable along the rail 64b, and moves to the end of the rail 64b as shown in FIG. 5A when the fuel debris X2 is recovered. The manipulator arm 64a can also be attached and detached with an arbitrary processing tool in the same manner as the manipulator arms 46 and 53 of the work manipulator unit 34 and the handling manipulator unit 36. The manipulator arm 64 a extends from the side auxiliary shielding chamber 63 to a power supply cable, piping for supplying hydraulic pressure, and wiring and piping 64 c such as process gas piping for using a laser cutting machine.

  The side auxiliary shielding chamber 63 is formed on the transport carriage and is movable. By mounting the manipulator unit 64 in a modular manner on the transport cart, the manipulator unit 64 can be easily replaced.

  Further, in the side shielding chamber 61, a first divided door 73 is provided on the wall on the biological shielding wall 13 side, and a second divided door 74 is provided in the communication opening 72.

  As shown in the front views of FIGS. 5 (b) and 5 (c), the first divided door 73 and the second divided door 74 are both upper doors 73 a, 74 a (first Door) and lower doors 73b and 74b (second door). Specifically, the upper doors 73a and 74a have a vertical width that allows the wiring and piping 64c (connecting member) to pass therethrough, and the lower doors 73b and 74b have rails 64b and a folded manipulator arm 64a (manipulator body). Has a vertical width enough to pass through.

  By closing (fully closing) both the upper door 73a and the lower door 73b of the first divided door 73 configured in this way, the hermetic cylinder 62 is closed, and the side shielding chamber 61 and the reactor containment vessel 12 The space is kept airtight. Further, the communication opening 72 is closed by closing (fully closing) both the upper door 74a and the lower door 74b of the second divided door 74, and the space between the side shielding chamber 61 and the side auxiliary shielding chamber 63 is reduced. It is kept airtight.

  On the other hand, when the manipulator arm 64a passes through the airtight cylinder 62, both the upper door 73a and the lower door 73b of the first divided door 73 and the second divided door 74 are opened (fully opened). Further, when the manipulator arm 64 a passes through the communication opening 72, both the upper door 74 a and the lower door 74 b of the second divided door 74 are opened (fully opened). Then, after the manipulator arm 64a passes to the pedestal 17 side, the upper doors 73a and 74a are opened and the lower doors 73b and 74b are closed. In the rail 64b in this embodiment, the first divided door 73 portion and the second divided door 74 portion are cut out to such an extent that the manipulator arm 64a can travel, and interfere with the opening and closing of the lower doors 73b and 74b. Shall not.

  The walls and ceiling of the first divided door 73, the second divided door 74, the airtight cylinder 62, the side shielding chamber 61, and the side auxiliary shielding chamber 63 are each made of a shielding material, and radiation and radioactive substances are externally provided. It is configured not to leak.

  The side access recovery device 60 configured in this manner performs cutting, crushing, pulverization, and the like of the fuel debris X2 by the manipulator arm 64a of the manipulator unit 64 during the recovery operation of the fuel debris X2. Further, a collection container (not shown) is transferred to the vicinity of the fuel debris X2 by the manipulator arm 64a, and a section of the fuel debris X2 is stored in the collection container by the manipulator arm 64a. The collection container in which the fuel debris X2 is accumulated is returned into the side shielding chamber 61 by the manipulator arm 64a. And it carries out with the waste transfer trolley (not shown) connected to the side part shielding chamber 61. FIG. In addition, it is also possible to carry out with a carrying-out cart through another route from the pedestal opening 17a.

  The first divided door 73 and the second divided door 74 are fully opened only when the manipulator arm 64a passes, and after the manipulator arm 64a passes, the lower doors 73b and 74b are closed to restrict the flow area. Thereby, the inflow of radioactive material from the reactor containment vessel 12 to the side shielding chamber 61 is restricted, and the inflow of radioactive material from the side shielding chamber 61 to the side auxiliary shielding chamber 63 is further restricted. .

  Specifically, manipulators and robots generally used in high-dose rate areas are installed in low-dose rate areas without mounting control circuits on manipulators and robots. Become. Accordingly, for example, if an opening is provided in the door to allow the wiring and piping to pass therethrough, the area of the opening becomes large, and sufficient shielding and airtight functions cannot be maintained. Therefore, by providing the upper doors 73a and 74a and the lower doors 73b and 74b like the divided doors 73 and 74 of this embodiment, it is possible to cope with a case where complete shielding and airtightness are required.

  When the manipulator unit 64 is returned to the side auxiliary shielding chamber 63, the first divided door 73 is first fully opened, and after the manipulator unit 64 is once stored in the side shielding chamber 61, the first divided door 73 is fully closed. And Subsequently, the second divided door 74 is fully opened, and the manipulator unit 64 is stored in the side auxiliary shielding chamber 63. In this way, a so-called air lock system is adopted, but when the first divided door 73 is fully opened to return the manipulator unit 64 into the side shielding chamber 61, the lower door 74b of the second divided door 74 is closed, Since only the upper door 74a is opened, most of the radiation from the reactor containment vessel 12 can be shielded. In addition, it is possible to prevent the contamination area from being enlarged, and it is also possible to reduce the shielding thickness of the side auxiliary shielding chamber 63, thereby achieving an effect of reducing the weight.

  Next, the ventilation structure of the reactor building 1 will be described with reference to FIG.

  As shown in FIG. 6, the upper shielding chamber 32 and the side shielding chamber 61 are supplied with gas for supplying process gas necessary for use in a laser cutting machine by corresponding manipulator units 34, 36, and 64, respectively. A device 80 (gas supply means) is provided. An air supply device 81 for taking in air from the outside is provided in each of the auxiliary shielding chambers 33 and 63. The gas supplied by the gas supply device 80 may be a gas other than the process gas, for example, and includes all gases such as air.

Further, the reactor containment vessel 12 has a nitrogen supply device 82 (gas supply means) for supplying nitrogen (N ₂ ) in order to prevent an explosion caused by hydrogen (H ₂ ) retention in the reactor building 1. It is connected.

  Further, the reactor containment vessel 12 is provided with an exhaust passage 83, and the exhaust passage 83 is provided with a radioactive substance removing unit 84 (radioactive substance removing means) and an exhaust fan 85 (exhaust amount adjusting means). The radioactive substance removing unit 84 and the exhaust fan 85 are provided outside the reactor building 1, and are provided, for example, in a turbine building (not shown).

  The radioactive substance removing unit 84 is provided with devices for processing radioactive substances in multiple stages, and roughly includes a wet removing apparatus 84a and a dry removing apparatus 84b. More specifically, the wet removal device 84a includes, for example, an absorption tower, an electrostatic precipitator, a condenser, a demister, and the like, and the dry removal device 84b includes a heater, HEPA (High Efficiency Particulate Air Filter), iodine. A filter or the like is provided.

  The exhaust fan 85 performs exhaust at a flow rate higher than the total flow rate of the process gas supply flow rate by the gas supply device 80, the air supply amount by the air supply device 81, and the nitrogen supply flow rate by the nitrogen supply device 82. The inside of the pressure vessel 11 and the reactor containment vessel 12 is maintained in a negative pressure state.

  Comparing the contamination levels of the respective chambers in the reactor building 1, the reactor pressure vessel 11 and the reactor containment vessel 12 where the fuel debris X1 and X2 are recovered are the highest contamination level (high level contamination). Become.

  The upper shielding chamber 32 that communicates with the reactor containment vessel 12 is partitioned from the reactor containment vessel 12 through an airtight sheet 35, and the collection vessel 54 is partially allowed to pass through the collection vessel 54. It has only been done. For this reason, even during the recovery operation of the fuel debris X1 by the top access recovery device 30, the airtightness of both spaces is maintained high, and the contamination level in the upper shielding chamber 32 is lower than that in the reactor containment vessel 12 (medium level contamination). It becomes.

  Also in the side shielding chamber 61, an airtight cylinder 62 communicating with the reactor containment vessel 12 is partitioned by a first divided door 73, and a manipulator arm 64a is provided with rails 64b to perform a recovery operation of the fuel debris X2. Even when located at the tip, the lower door 73b of the first divided door 73 is closed, and only the region through which the wiring / piping 64c passes is opened. For this reason, even during the recovery operation of the fuel debris X2 by the side access recovery device 60, the airtightness of both spaces is maintained high, and the side shielding chamber 61 has a lower contamination level (medium level contamination) than the reactor containment vessel 12. It becomes.

  Since the upper auxiliary shielding chamber 33 communicating with the upper shielding chamber 32 is kept airtight except when necessary by the shielding door 43, the contamination level is lower than that of the upper shielding chamber 32 (low level contamination). Become. Further, the side auxiliary shielding chamber 63 communicating with the side shielding chamber 61 is partitioned by a second divided door 74 similar to the first divided door 73, so that it is lower than the side shielding chamber 61. Contamination level (low level contamination).

  As described above, the upper shielding chamber 32 is sealed by the airtight sheet 35, the side shielding chamber 61 by the first divided door 73, the upper shielding chamber 32, the side shielding chamber 61, the reactor containment vessel 12 and the reactor pressure vessel 11. Since the opening to is limited, the exhaust amount by the exhaust fan 85 can be suppressed. Since the exhaust amount can be suppressed, the load on the wet removal device 84a and the dry removal device 84b is reduced, and the radioactive material can be reliably removed. Thereby, the ventilation at the time of fuel debris collection | recovery which concerns on this embodiment can remove a radioactive substance more efficiently.

  Although the description of the embodiments of the fuel debris recovery ventilation system and the fuel debris recovery ventilation method according to the present invention is finished above, the embodiment is not limited to the above embodiment.

  The present invention is not limited to the above-described embodiment, and can be applied to, for example, boiling water reactors having different types or nuclear reactors other than boiling water reactors, and the like without departing from the spirit of the present invention. Various changes are possible.

  For example, in the above embodiment, the airtight sheet 35 has a hat shape, but the shape of the airtight sheet is not limited to this, and for example, a rectangular sheet is cured along the outer shape of the upper platform of the work manipulator unit. May be.

  Moreover, in the said embodiment, although the collection container introduction part 48 of the airtight sheet 35 has comprised what is called a chrysanthemum crack shape, the shape of a collection container introduction part is not restricted to this. For example, the collection container introduction part may be a circular lid that can be opened and closed. The lid member is automatically opened and closed by an actuator or the like when passing through the collection container.

  In the above embodiment, the side access collection device 60 accesses the fuel debris X2 through the through passage 70 and the side opening 71, but a plurality of accessible routes may be formed. For example, a through-passage and a side opening may be formed at two locations, and two systems of a route for cutting fuel debris and a route for collecting a section of fuel debris may be provided. Also in that case, the same effect as the above-mentioned embodiment can be produced by partitioning each shielding room with a divided door.

DESCRIPTION OF SYMBOLS 1 Reactor building 11 Reactor pressure vessel 12 Reactor containment vessel 13 Biological shielding wall 17 Pedestal 17a Pedestal opening 30 Top access recovery device (recovery means)
32 Upper shielding room 33 Upper auxiliary shielding room 34 Manipulator unit for work (working part)
35 Airtight sheet (compartment means)
36 Manipulator unit for cargo handling (loading department)
42 Communication opening (communication part)
43 Shielding door (opening / closing means)
48 collection container introduction part 48a tongue piece 54 collection container 55 water spray (refrigerant injection means)
60 Side access collection device (collection means)
61 Side shielding chamber 62 Airtight cylinder 63 Side auxiliary shielding chamber 64 Manipulator unit 64a Manipulator arm (manipulator body)
64b Rail 64c Wiring / Piping (connecting member)
70 Through passage (through hole)
71 Side opening (through hole)
72 Communication opening (communication part)
73 First split door 73a Upper door (first door)
73b Lower door (second door)
74 Second divided door 74a Upper door 74b Lower door 80 Gas supply device (gas supply means)
81 Air supply device 82 Nitrogen supply device (gas supply means)
83 Exhaust passage (displacement adjustment means)
84 Radioactive substance removal unit (Radioactive substance removal means)
84a Wet removal device 84b Dry removal device 85 Ventilator

Claims (6)

A fuel debris recovery ventilation system for recovering solidified fuel debris in a reactor pressure vessel or a reactor containment vessel,
A shielding room in communication with the reactor containment vessel;
Recovery means for approaching the fuel debris from the shielding chamber and performing a recovery operation of the fuel debris;
Partitioning means for partitioning between the shielding chamber and the reactor containment vessel while partially allowing passage of the recovery means;
Gas supply means for supplying gas from the outside into the shielding chamber;
An exhaust amount adjusting means for exhausting from the reactor containment vessel at a flow rate higher than a gas flow rate supplied by the gas supply means;
A radioactive substance removing means for removing the radioactive substance in the exhaust;
With fuel debris recovery ventilation system. The shielding chamber is an upper shielding chamber installed above the reactor pressure vessel,
The recovery means includes a working unit that performs a recovery operation on the fuel debris, and a cargo handling unit that transfers the fuel debris into the upper shielding chamber.
The partitioning means is an airtight sheet that covers the working portion on the reactor containment vessel side in the upper shielding chamber and partitions the cargo handling portion side, and the airtight sheet is temporarily allowed to allow passage of the cargo handling portion. The fuel debris recovery ventilation system according to claim 1, further comprising an introduction portion that is opened. 2. The apparatus according to claim 1, further comprising a refrigerant injection unit that is provided around an opening that communicates between the shielding chamber and a reactor well formed above the reactor pressure vessel, and that injects a refrigerant into the reactor well. 2. A ventilation system for collecting fuel debris according to 2. The reactor containment vessel is surrounded by a biological shielding wall, and through holes are formed at corresponding positions on the side surface of the reactor containment vessel and the side surface of the biological shielding wall,
The shielding chamber is a side shielding chamber that covers the through hole in close contact with the side surface of the biological shielding wall;
The recovery means is a manipulator that recovers the fuel debris from the side shielding chamber through the through hole,
The partition means is a divided door that can be opened and closed independently by each of the divided parts, and the divided door is connected to the manipulator and a first door that opens and closes an area through which a main body portion of the manipulator passes. The fuel debris recovery ventilation system according to claim 1, further comprising: a second door that opens and closes a region through which the connected connecting member passes. Further, an auxiliary shielding room communicated with the shielding room via a communication part;
The fuel debris recovery ventilation system according to any one of claims 1 to 4, further comprising opening / closing means for opening and closing the communication portion. A fuel debris recovery ventilation method for recovering solid fuel debris in a reactor pressure vessel or a containment vessel,
Providing a shielding chamber in communication with the reactor containment vessel;
A recovery step of approaching the fuel debris from the shielding chamber and performing a recovery operation of the fuel debris;
Providing partitioning means for partitioning between the shielding chamber and the reactor containment vessel while partially allowing passage of the member accompanying the recovery operation in the recovery step;
A gas supply step of supplying a gas from the outside into the shielding chamber;
A displacement adjustment step of exhausting from the reactor containment vessel at a flow rate higher than the flow rate of the gas supplied in the gas supply step;
A radioactive substance removal step of performing a removal treatment on the radioactive substance in the exhaust;
Ventilation method when collecting fuel debris.

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