JP4000032B2 - Furnace bottom working device and working method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a furnace bottom working apparatus and a working method for performing inspection, inspection, preventive maintenance, or repair work at the bottom inside a pressure vessel of a boiling water reactor (BWR).
[0002]
[Prior art]
The structure of the boiling water reactor is as shown in FIG. That is, an upper lattice plate 2, a core support plate 3, a CRD (control rod drive mechanism) housing 4, and a stub tube 5 are installed as structures inside the pressure vessel 1. A fuel assembly 6 is detachably installed between the upper lattice plate 2 and the core support plate 3, and a control rod guide tube 7 is detachably installed between the core support plate 3 and the CRD housing 4. An in-core guide tube 8 is installed between the CRD housings 4.
[0003]
When working at the bottom of a boiling water reactor having such a structure, the fuel assembly 6, the control rod guide tube 7, the fuel support bracket, the control rod, After removing the control rod drive mechanism, the work apparatus is remotely operated after the work apparatus is installed at the place.
[0004]
For example, the following Patent Document 1 discloses a type of wire that can be bent in only one direction with a TV camera attached to the tip after removing the fuel assembly, control rod guide tube, fuel support bracket, control rod, and control rod drive mechanism. An apparatus for performing a wide range of inspections and the like by pushing the guide body is disclosed.
[0005]
Patent Document 2 below discloses an apparatus for repairing and inspecting the neutron flux monitor housing by removing a working mechanism for holding the neutron flux monitor housing and driving it around after the reactor internal structure is removed. .
[0006]
However, although the apparatus disclosed in Patent Document 1 can be inserted from one place and can be operated in a wide range, the welded portion of the stub tube and the pressure vessel (RPV) as the welded portion of the furnace bottom, the stub tube and the CRD housing Among the welded portions, it is difficult to apply to the welded portions of the stub tube and the CRD housing in terms of dimensions, and it is not suitable for work that receives reaction force such as polishing work.
[0007]
Although the apparatus disclosed in Patent Document 2 can perform work that receives a reaction force with high positional accuracy, the range of work that can be performed by a single installation is limited. In the furnace bottom working apparatus configured as described above, maintenance work cannot be performed with high accuracy while receiving a reaction force on a target welded part in a wide range of the furnace bottom by a single installation work.
[0008]
[Patent Document 1]
JP-A-9-288197 [0009]
[Patent Document 2]
JP-A-7-63879 [0010]
[Problems to be solved by the invention]
As described above, in the conventional furnace bottom working device, there is a problem that inspection inspection, preventive maintenance, polishing and repair work of a wide range of welded parts cannot be performed with a small number of installation work, including work receiving reaction force. is there.
[0011]
Accordingly, the present invention provides a reactor bottom working device and a working method capable of performing a wide range of inspections, repairs, etc. of the reactor bottom while minimizing preparation work for removing the fuel assemblies, control rod guide tubes, etc. The purpose is to do.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, a first aspect of the present invention is a housing having an arcuate cross section, a first propelling means attached to the housing and moving the housing in a direction perpendicular to the cross section, and the housing attached to the housing. Second propulsion means for moving the casing in a direction parallel to the cross section, driving means attached to the inside of the arc of the casing and moving the casing along the arc, and a work head attached to the casing And a control device that controls the first propulsion unit, the second propulsion unit, the drive unit, and the work head.
[0013]
According to a second aspect of the present invention, there is provided a travel distance measuring device having a follower wheel and a sensor that are attached to the inside of the arc of the housing and rotate while contacting the work object.
According to a third aspect of the present invention, the housing includes a plurality of blocks coupled to each other by a hinge mechanism in a direction parallel to the arcuate cross section, the actuator for rotating the hinge mechanism, and the thrust of the second propulsion means It is set as the structure provided with the rotation mechanism which changes the direction of.
[0014]
According to a fourth aspect of the present invention, there is provided a distance measuring device for measuring a distance from an adjacent furnace bottom structure attached outside the arc of the housing , and an operation for processing a signal from the distance measuring device and the travel distance measuring device. It is set as the structure provided with a vessel.
[0015]
According to a fifth aspect of the present invention, a support device having a cylindrical main body is installed on the upper part of the CRD housing at a location where the control rod guide tube in the nuclear reactor is removed, and the reactor bottom working device according to the first aspect passes through the main body. Is installed at the bottom of the reactor, and the power / information transmission means connected to the furnace bottom working device is handled by the power / information transmission means handling device provided in the support device, so that the work at the bottom of the reactor is performed.
[0016]
DETAILED DESCRIPTION OF THE INVENTION
A furnace bottom working apparatus according to a first embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 1, the furnace bottom working apparatus of the present embodiment has a semicircular cross section, the upper inner diameter is substantially the same as the CRD housing outer diameter, and the lower inner diameter is substantially the same as the stub tube outer diameter. Thus, a vertical body which is a first propulsion means which includes a housing 10 having an outer diameter of 276 mm or less, a motor 11 and a screw 12 attached to the housing 10 and moves the housing 10 in a direction perpendicular to the semicircular arc cross section thereof. Two propulsion units which are composed of a direction propulsion unit 13, a motor 20 and a screw 21 and which are attached so that their rotational axes form 90 degrees with each other and move the casing 10 in a direction parallel to the semicircular arc-shaped cross section. Parallel direction propulsion units 22a and 22b and another direction propulsion unit 22c, which is another second propulsion unit, are provided so as to be driven in a direction connecting both ends of the semicircular arc of the housing 10.
[0017]
The furnace bottom working device of the present embodiment is a driving means that is rotated by two motors 30a and 30b (30b is not shown) that are separately attached to the side (inside) having a small radius of curvature of the casing 10. A driving wheel 31a, 31b (31b is not shown), a travel distance measuring device 42 composed of a slave wheel 40 and a sensor 41, which are also mounted on the side of the housing 10 having a small radius of curvature, and one or both sides of a semicircular arc And a control head 100 for remotely performing each operation, and a cable 60 and a hose 70 for connecting the control device 100 and the housing 10.
[0018]
The reactor bottom working device of the present embodiment configured as described above is dropped into the reactor water, and the vertical direction propulsion unit 13 and the parallel direction propulsion units 22a and 22b are operated remotely from the control device 100, as shown in FIG. The fuel assembly 6 and the control rod guide tube 7 are removed from the core shown, and the upper lattice plate 2 and the core support plate 3 of the cell are made to enter the bottom of the reactor.
[0019]
As shown in FIG. 2, the parallel-direction propulsion units 22a, 22b, and 22c can move the casing 10 back and forth, right and left, or swivel by a combination of thrusts in directions parallel to the semicircular arc-shaped cross section of the casing 10. The vertical movement at the bottom of the furnace is caused by the thrust of the vertical thruster 13, and the horizontal movement is caused by the parallel thrusters 22a, 22b and 22c. After positioning the target CRD housing 4 by using these moving functions, the thrust of the parallel direction propulsion units 22a and 22b is brought close to the CRD housing 4 and the stub tube 5 and circulated by the drive wheels 31a and 31b. The work is performed by the work head 50. After completion of the work, as shown in FIG. 3, the same work is performed by moving to the next CRD housing 4 and stub tube 5.
[0020]
As described above, the furnace bottom working device of the present embodiment has the vertical thruster 13 and the parallel direction after the fuel assembly 6, the control rod guide tube 7, the fuel support bracket, the control rod and the control rod drive mechanism are removed. Using the propulsion units 22a, 22b, and 22c, they pass through the openings of the upper lattice plate 2 and the core support plate 3 and reach the bottom of the furnace. And after positioning to the CRD housing 4 using a parallel direction propulsion unit and a vertical direction propulsion unit, the drive wheels 31a and 31b are rotated by pressing the drive wheels 31a and 31b against the CRD housing 4 by the parallel direction propulsion unit. To do. The work head 50 attached to one side or both sides of the semicircular arc of the housing 10 can work the entire circumference of the CRD housing 4. At the same time, the slave wheel 40 of the travel distance measuring device 42 is also pressed, the movement distance is calculated by the rotation sensor, and the position is detected. After the entire circumference is completed, the same operation is performed by positioning the next CRD housing with a vertical thruster and a parallel thruster.
[0021]
According to the reactor bottom working device of the present embodiment, it is possible to perform operations such as inspection inspection, preventive maintenance, and repair of the reactor bottom without removing a large number of fuel assemblies 6, control rod guide tubes 7, etc. Work can be carried out in a short time. In addition, since the structure can be reliably moved from the base point and the position can be grasped by the travel distance measuring device 42, the work quality is good. In this way, with a minimum of preparatory work, a wide range, many types, and high-quality work can be performed, which can contribute to shortening the periodic inspection time of the nuclear power plant and improving the operating rate.
[0022]
Next, a second embodiment of the furnace bottom working apparatus according to the present invention will be described with reference to FIGS. In the furnace bottom working apparatus according to the present embodiment, the casing 10 includes three blocks, and these blocks are connected to each other by hinges 26a and 26b that are actively rotated by motors 25a and 25b. Although not shown, the housing 10 is provided with a rotation mechanism that changes the direction of the parallel thruster.
[0023]
As shown in FIG. 5 (a), the furnace bottom portion working device of the present embodiment rotates the hinges 26a and 26b so that the housing 10 bends when passing through the core support plate 3. Can be reduced. Further, when passing through a narrow gap at the bottom of the furnace, as shown in FIG. 5B, the narrow gap can be passed by rotating the hinges 26a and 26b so that the casing 10 is deployed.
[0024]
The furnace bottom working apparatus of the present embodiment can change the cross-sectional shape of the casing 10 by the hinge mechanisms 26a and 26b, and can change the shape when passing through the core support plate 3 and the shape at the furnace bottom. Therefore, it is possible to easily pass between the CRD housing 4 and the in-core guide tube 8, and a wider range of work is possible. It is also possible to mount a larger work head.
[0025]
Next, a third embodiment of the furnace bottom working apparatus according to the present invention will be described with reference to FIGS. As shown in FIG. 6, the furnace bottom working apparatus of this embodiment includes an ultrasonic rangefinder 80 attached to the rear surface of the housing 10 and a detection circuit (not shown) that detects the shortest distance by signal processing the output. ).
[0026]
According to this embodiment, as the position of the housing 10 rotates along the CRD housing 4 to positions a, b, and c in FIG. 6A, as shown in FIG. 7, the adjacent CRD housing 4a. 4c and the reflection of sound waves from the in-core guide tube 8, the output of the ultrasonic distance meter 80 changes. By obtaining the peak of this output, it is possible to detect the closest position and know the absolute angle of the reactor bottom working device with respect to the nuclear reactor.
[0027]
When the furnace bottom working device of the present embodiment rotates close to the CRD housing 4, the furnace bottom working device detects the adjacent CRD housing from the shortest distance position of the output signal of the ultrasonic rangefinder 80, and thereby determines its own position. Can be identified. Further, by detecting the next adjacent CRD housing along with the rotation, it is possible to correct the error of the mileage measuring instrument 42, and more accurate position detection can be performed, so that the reliability of data is improved.
[0028]
As described above, according to the present embodiment, the rotational position of the reactor bottom working device can be accurately detected with respect to the nuclear reactor, so that the reproducibility of the position is ensured and the work quality is improved. Further, since the positioning accuracy is improved, it is possible to indicate the work position on the drawing.
[0029]
Next, a furnace bottom working method according to a fourth embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 8, the furnace bottom part working method is the furnace bottom part work of the first to third embodiments in which the cable 60 and the hose 70 which are transmission means for transmitting and receiving power and information to and from the outside of the furnace are connected. The device 10a is introduced into the bottom of the furnace by an assist device 110 attached to the top of the CRD housing 4 where the control rod guide tube 7 has been removed.
[0030]
The support device 110 has a cylindrical main body installed on the upper part of the CRD housing. In the main body, a guide tube 112 having a slope 111 at the lower end, a motor 120, a screw 121, and a linear guide 122 are provided. A vertical mechanism 124 configured to move the guide tube 112 up and down, a feed mechanism 132 composed of a motor 130 and a roller 131 mounted on the vertical mechanism 124, and a hose 70 and a cable 60 fixed to a tip portion of the wheel 140. Is attached, and a flexible wire 141 is partially sandwiched between rollers 131 of the feed mechanism 132. The wheel 140 and the wire 141 constitute a power / information transmission means handling device.
[0031]
In the furnace bottom working method of the present embodiment, as shown in FIG. 9, the vertical mechanism 124 is positioned at the top, and the flexible wire 141 is pulled up to the root of the guide tube 112 by the feed mechanism 132, In a state where the work device 10a is housed in the support device 110, the control rod guide tube 7 is installed in the lower part of the furnace. Next, the vertical mechanism 124 is operated to lower the guide tube 112 to the furnace bottom, and at the same time, the furnace bottom working device 10a is moved from the support device 110 to the furnace bottom. Thereafter, the cable 60 and the hose 70 are fed by the wire 141 by the feeding mechanism 132 while moving the furnace bottom working device 10 a to the predetermined CRD housing 4. The bottom of the furnace can be smoothly moved by the wheel 140 at the tip of the wire 141.
[0032]
In the furnace bottom part working method of the present embodiment, the support device 110 is supported by the flexible wire 141 that assists the feeding and storage of the cable 60 and the hose 70 connected to the furnace bottom part working device 10a and the feeding mechanism 132. Therefore, the load on the vertical direction propulsion device and the parallel direction propulsion device can be reduced, and the movement can be easily performed. In addition, the workability is improved because the cables and hoses are stably routed, and the applicability of the furnace bottom working device is expanded.
[0033]
As described above, according to the present embodiment, by combining the support device 110 and the furnace bottom working device 10a, there is no need to pull the cable 60 and the hose 70 by the furnace bottom working device 10a for a long distance, and the furnace bottom working device 10a. Is easy to move and can perform a wide range of work at the bottom of the furnace.
[0034]
Next, a furnace bottom working method according to a fifth embodiment of the present invention will be described with reference to FIG. This embodiment includes an imaging device 150 such as a TV camera and an illumination 151 attached to the guide tube 112 in addition to the configuration of the fourth embodiment.
[0035]
According to the furnace bottom part working method of this embodiment, the state of the cable 60 and the hose 70, the position of the furnace bottom part working apparatus 10a, the positional relationship with the stub tube 5 of the flexible wire 141, etc. are remotely grasped and accurately detected. Work can be done.
[0036]
【The invention's effect】
According to the present invention, there is provided a reactor bottom working apparatus and work method capable of minimizing preparation work for removing a fuel assembly, a control rod guide tube, etc., and performing a wide range inspection, repair, etc. of the reactor bottom. Can be provided.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a configuration of a furnace bottom working device according to a first embodiment of the present invention.
FIG. 2 is a plan view for explaining horizontal movement (a), (b), (d) and turning (c) operations of the furnace bottom working apparatus according to the first embodiment of the present invention.
FIG. 3 is a plan view for explaining a transition operation between adjacent CRD housings or stub tubes of the furnace bottom working apparatus according to the first embodiment of the present invention.
FIG. 4 is a plan view showing a configuration of a furnace bottom working device according to a second embodiment of the present invention.
FIGS. 5A and 5B are diagrams illustrating an operation of a furnace bottom portion working apparatus according to a second embodiment of the present invention, wherein FIG. 5A is a plan view and FIG.
6A and 6B illustrate the operation of the furnace bottom working apparatus according to the third embodiment of the present invention, wherein FIG. 6A is a plan view and FIG. 6B is a longitudinal sectional view.
FIG. 7 is a curve diagram for explaining the operation of the furnace bottom working apparatus according to the third embodiment of the present invention.
FIG. 8 is a longitudinal sectional view of a furnace bottom portion for explaining a furnace bottom portion working method according to a fourth embodiment of the present invention.
FIG. 9 is a longitudinal sectional view of the furnace bottom portion for explaining the operation of the furnace bottom portion working method according to the fourth embodiment of the present invention.
FIG. 10 is a longitudinal sectional view of a furnace bottom portion for explaining a furnace bottom portion working method according to a fifth embodiment of the present invention.
FIG. 11 is a longitudinal sectional view of a boiling water reactor according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Pressure vessel, 2 ... Upper lattice board, 3 ... Core support plate, 4, 4a, 4c ... CRD housing, 5, 5a, 5c ... Stub tube, 6 ... Fuel assembly, 7 ... Control rod guide tube, 8 ... In-core guide tube, 10 ... housing, 10a ... furnace bottom working device, 11 ... motor, 12 ... screw, 13 ... vertical thruster, 20 ... motor, 21 ... screw, 22a, 22b, 22c ... parallel thruster, 25a 25b ... motor, 26a, 26b ... hinge, 30 ... motor, 31a ... drive wheel, 40 ... slave wheel, 41 ... sensor, 42 ... travel distance measuring instrument, 50 ... work head, 60 ... cable, 70 ... hose, 80 ... Ultrasonic distance meter, 100 ... control device, 110 ... support device, 111 ... slope, 112 ... guide tube, 120 ... motor, 121 ... screw, 122 ... linear guide, 124 ... vertical mechanism, 30 ... motor, 131 ... roller, 132 ... feeding mechanism, 140 ... wheel, 141 ... wire, 150 ... imaging device, 151 ... lighting.

Claims (5)

  A housing having an arcuate cross section; first propulsion means attached to the housing for moving the housing in a direction perpendicular to the cross section; and a first propulsion means attached to the housing for moving the housing in a direction parallel to the cross section. Two propulsion means, drive means attached to the inside of the arc of the enclosure, and moving the enclosure along the arc; a work head attached to the enclosure; the first propulsion means; the second propulsion A furnace bottom working device comprising: means, a drive means, and a control device for controlling the work head.   The furnace bottom working device according to claim 1, further comprising a travel distance measuring device having a follower wheel and a sensor that are attached to the inside of the arc of the housing and rotate while contacting a work object.   The housing is composed of a plurality of blocks coupled to each other by a hinge mechanism in a direction parallel to the arcuate cross section, and an actuator for rotating the hinge mechanism and a rotating mechanism for changing the direction of thrust of the second propulsion means The furnace bottom working apparatus according to claim 1, further comprising: A distance measuring device for measuring a distance from an adjacent furnace bottom structure attached outside the arc of the housing, and a computing unit for processing a signal from the distance measuring device and the travel distance measuring device; The furnace bottom working device according to claim 2.   A support device having a cylindrical main body is installed on the upper part of the CRD housing at a location where the control rod guide tube in the nuclear reactor is removed, and the reactor bottom working device according to claim 1 is installed in the reactor bottom through the main body. A reactor bottom working method characterized in that a work at the bottom of a nuclear reactor is performed while handling power / information transmission means connected to the reactor bottom working device with a power / information transmission means handling device provided in the support device.

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