JP6672086B2 - Inspection apparatus and inspection method for core tank - Google Patents

Description

  The present disclosure relates to an inspection device and an inspection method for a reactor core tank of a nuclear reactor.

  Generally, as one of inspections for evaluating the soundness of a nuclear reactor, it is required to inspect the state of a welded portion of a reactor core vessel. The core tank is usually formed by welding a plurality of plates into a cylindrical shape.However, when used in a harsh environment, defects such as cracks and breakage can occur in welds that are more vulnerable than other parts. Likely to happen. Therefore, in the inspection of the core tank, it is required to mainly inspect the welded portion.

  2. Description of the Related Art Conventionally, in inspection of a core tank, a core tank removed from a nuclear reactor is placed in an upright posture, and a visual inspection of the core tank is performed using a remotely operated camera. At this time, it has been common to introduce a camera suspended from above the core tank by a crane or the like into the core tank and bring the camera closer to the welded portion by remote control to take an image.

In recent years, requirements regarding the moving speed and photographing range of a camera have become strict, and as a configuration corresponding to this requirement, for example, Japanese Patent Application Laid-Open No. H11-163873 discloses a moving apparatus that moves an inspection apparatus including a camera along the outer peripheral surface of a core tank. A mechanism is disclosed.
Further, in the inspection of the core tank, it may be required to perform an inspection in a narrow portion. For example, Patent Documents 2 and 3 disclose a method of inspecting a weld in a narrow portion. In this method, a fiber scope and a UT probe are hung down on a traveling roller that moves along the upper end of a heat shield disposed on the outer peripheral side of a core tank, and a visual inspection of a welded portion is performed by the fiber scope, and a UT probe is used. Nondestructive inspection of the welded portion is performed by using the method.

International Publication No. 2011/070788 JP-A-8-226991 JP-A-8-226990

However, when inspecting the welded portion by observing the welded portion of the core bath using the imaging unit, scale and the like adhere to the core bath due to aging, and the visibility of the welded portion is reduced. Incorrect inspection may be performed based on the image.
In this regard, Patent Literatures 1 to 3 do not disclose a method for appropriately performing an inspection of a welded portion using an imaging unit when the visibility of the welded portion is reduced due to aging of the core bath.

  In view of the above circumstances, at least some embodiments of the present invention provide an inspection apparatus and an inspection method for a core tank that can appropriately perform an inspection of a welded part even in a core tank whose visibility is reduced due to aging. The purpose is to provide.

(1) A core tank inspection apparatus according to at least some embodiments of the present invention includes:
An apparatus for inspecting a weld bead extending along a circumferential direction of a core tank of a nuclear reactor,
A bead sensor for detecting the weld bead,
An imaging unit for imaging the weld bead,
Supporting the bead sensor and the imaging unit, a carrier configured to be movable in the circumferential direction of the core vessel,
During the detection of the weld bead by the bead sensor, a first actuator configured to move the bead sensor and the imaging unit along the axial direction of the core bath,
A second actuator configured to move the carrier in the circumferential direction at a position where the bead sensor detects the weld bead during imaging of the weld bead by the imaging unit;
Is provided.

The core tank inspection apparatus of (1) includes a bead sensor for detecting a weld bead, and an imaging unit for imaging the weld bead. Then, the welding bead is imaged by the imaging unit at the position where the bead sensor detects the welding bead. This makes it possible to appropriately image the welding bead without overlooking the weld bead even in the core tank in which the visibility is reduced due to aging.
Further, as a moving mechanism of the bead sensor and the imaging unit, a first actuator configured to move the bead sensor and the imaging unit along the axial direction during detection of the weld bead by the bead sensor, and during imaging of the welding bead by the imaging unit. And a second actuator configured to move the carrier in a circumferential direction at a position where a bead sensor detects a weld bead. The bead sensor moved in the axial direction by the first actuator detects the position of the weld bead in the height direction, and the imaging unit is moved in the circumferential direction together with the carrier by the second actuator at the height position, so that, for example, Like a weld bead extending in the horizontal direction, a long weld bead extending in the core tank along the horizontal direction can be reliably detected and appropriately imaged.

(2) In some embodiments, in the configuration of the above (1),
In a state positioned in the radial direction of the core tank, further comprising a traveling rail attached to the core tank along the circumferential direction,
The carrier is configured to be able to travel along the travel rail.

  According to the configuration (2), since the traveling rails are attached to the core tank along the circumferential direction while being positioned in the radial direction of the core tank, the carrier can be accurately aligned along the traveling rail. Can be moved.

(3) In some embodiments, in the configuration of the above (2),
The traveling rail is attached to an upper flange of the core tank.

  According to the above configuration (3), since the traveling rail is attached to the upper flange of the core tank, the traveling rail can be easily attached and detached. In addition, since the upper flange of the core tank generally extends in the horizontal direction almost exactly, the running rail can be properly installed in the horizontal direction by following the upper flange.

(4) In some embodiments, in the configuration of the above (2) or (3),
The traveling rail has a plurality of fitting portions that can be respectively fitted to a plurality of positioning protrusions or recesses formed in the core bath.

  According to the configuration of the above (4), when the traveling rail is installed, the traveling rail can be accurately positioned with respect to the core tank by fitting the convex portion or the concave portion with the fitting portion. Thereby, the carrier, the bead sensor, and the imaging unit can be appropriately moved.

(5) In some embodiments, in any of the above configurations (2) to (4),
The traveling rail is
An annular rail portion continuous in the circumferential direction,
At least one bridge portion provided so as to cross the annular rail portion,
including.

  According to the above configuration (5), since at least one bridge portion is provided so as to cross the annular rail portion, the strength of the annular rail portion can be secured, and the annular rail portion can be secured even when the carrier moves. Can be stably supported.

(6) In one embodiment, in the configuration of the above (5),
The traveling rail further includes a rib provided on at least one of the annular rail section and the bridge section.

  According to the configuration (6), since the strength of the annular rail portion can be further improved, the annular rail portion can be prevented from bending even under the load of the carrier, the bead sensor, and the imaging unit, and the carrier can be prevented. Can be moved appropriately.

(7) In some embodiments, in the configuration of the above (5) or (6),
A traveling guide rod further has one end rotatably fixed to the at least one bridge portion on the center of the annular rail portion and the other end connected to the carrier.

  According to the configuration (7), the carrier can be accurately positioned in the radial direction of the core tank, and the carrier can be appropriately moved on the annular rail portion.

(8) In some embodiments, in any one of the above configurations (1) to (7),
The bead sensor, the imaging unit, and at least a part of the carrier are configured to be accessible in a gap between a heat shield provided on an outer peripheral side of the core tank and the core tank.

  According to the configuration of (8), it is possible to reliably detect a weld bead in a narrow portion between the core bath and the heat shield, and appropriately image the weld bead.

(9) In one embodiment, in the configuration of the above (8),
The inspection device, a narrow portion inspection carrier for inspecting the weld bead in the gap, and a non-narrow portion inspection carrier for inspecting the weld bead in an area not covered by the heat shield. Are configured to be exchangeable among a plurality of the carriers including:

  According to the configuration of the above (9), a plurality of types of carriers including a narrow portion inspection carrier and a non-narrow portion inspection carrier can be exchanged. Most areas of the tank can be properly inspected.

(10) In some embodiments, in any of the above configurations (1) to (9),
The first actuator is configured such that during movement of the carrier by the second actuator, at least one pin is located in a gap between the heat shield provided on the outer peripheral side of the core tank and the core tank. When the imaging unit approaches a directional position range, the imaging unit is configured to move in the axial direction such that the at least one pin is avoided by the imaging unit.

  According to the above configuration (10), for example, when a pin is provided on the outer peripheral side of the core tank such as a mounting pin of a heat shield, the imaging unit is moved in the axial direction so that the imaging unit avoids the pin. This makes it possible to move the carrier smoothly along the core tank while preventing interference between the imaging unit and the pins. Therefore, the efficiency of inspection work can be improved.

(11) In some embodiments, in any one of the above configurations (1) to (10),
The apparatus further includes a counterweight attached to the carrier.

  When a weld bead is detected or an image is taken, the center of gravity of the bead sensor and the imaging unit is located away from a support point that is a contact point between the traveling rail and the carrier. Therefore, the carrier can be stably moved by adjusting the weight balance of the carrier by the counter weight as in the configuration (11).

(12) In some embodiments, in any of the above configurations (1) to (11),
The bead sensor is attached to the carrier at a position shifted from the imaging unit.

  According to the configuration (12), since the positions of the bead sensor and the imaging unit are different, it is possible to monitor (detect or image) substantially the same surface by adjusting the respective angles.

(13) In some embodiments, in any one of the above configurations (1) to (12),
The inspection device,
A sensor feed cable connected to the bead sensor,
An imaging unit feed cable connected to the imaging unit,
The carrier includes a guide tube through which the sensor feed cable and the imaging unit feed cable are inserted,
The first actuator is configured to advance and retreat the sensor feed cable and the imaging unit feed cable within the guide tube to move the bead sensor and the imaging unit along the axial direction.

  According to the above configuration (13), the bead sensor and the imaging unit can be moved in the axial direction via the cables (the sensor feed cable and the imaging unit feed cable) inserted through the guide tube. At the first actuator. Therefore, it is possible to install the first actuator using a relatively large space, for example, a space above the core tank, instead of a narrow space near the bead sensor and the imaging unit.

(14) In one embodiment, in the configuration of the above (13),
The distal end portion of the guide tube is configured to be insertable into a gap between the heat shield and the core tank provided on the outer peripheral side of the core tank,
The bead sensor and the imaging unit are respectively suspended below the distal end of the guide tube by the sensor feed cable and the imaging unit feed cable extending inside the guide tube.

  According to the above configuration (14), if the inspection is performed in a state where the tip of the guide tube is inserted into the annular gap between the heat shield and the core tank, the bead sensor and the imaging unit are moved along the axial direction by the first actuator. When moving the bead sensor and the imaging unit, it is easy to enter the gap between the bead sensor and the imaging unit.

(15) An inspection method of a core tank according to at least some embodiments of the present invention includes:
A method for inspecting a weld bead extending along a circumferential direction of a core tank of a nuclear reactor,
Detecting the welding bead by the bead sensor while moving the bead sensor in the axial direction of the core bath;
While moving the imaging unit in the circumferential direction at the detection position of the welding bead by the bead sensor, imaging the welding bead by the imaging unit,
Is provided.

According to the core tank inspection method of the above (15), the welding bead is detected by the bead sensor while moving the bead sensor in the axial direction of the core tank, and the imaging is performed while the imaging unit is moved in the circumferential direction at the detected position. The unit images the weld bead. This makes it possible to appropriately image the weld bead without overlooking the weld bead even in the core tank whose visibility has been reduced due to aging.
Also, by detecting the position of the weld bead in the height direction by a bead sensor moved in the axial direction of the core tank, and moving the imaging unit in the circumferential direction at the height direction position to take an image, for example, in the horizontal direction of the core tank, It is possible to reliably detect a long weld bead extending in the core tank along the horizontal direction like a weld bead extending to the core tank, and appropriately image the weld bead.

  According to at least some embodiments of the present invention, a weld bead can be appropriately imaged without overlooking the weld bead even in a core tank whose visibility has been reduced due to aging. Further, for example, a long weld bead extending in the core tank along the horizontal direction, such as a weld bead extending in the horizontal direction of the core tank, can be reliably detected and appropriately imaged.

FIG. 1 is a side sectional view of a nuclear reactor according to one embodiment. It is a side view of a core tank concerning one embodiment. It is a perspective view showing the state where the inspection device of the core tank concerning one embodiment was attached to the core tank. It is a perspective view showing the schematic structure of the inspection device of the core tank concerning one embodiment. FIG. 4 is a diagram showing a cross section taken along line AA of FIG. 3. FIG. 5 is an enlarged view of a portion B in FIG. 4. FIG. 5 is an enlarged view of a portion C in FIG. 4. It is a side view of the carrier provided with the counterweight in one embodiment. It is a figure for explaining the inspection method of the core tank concerning one embodiment.

  Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in the embodiments or shown in the drawings are not intended to limit the scope of the present invention thereto, but are merely illustrative examples. Absent.

  First, with reference to FIG. 1, a description will be given of a nuclear reactor 1 including a core tank 30 to be inspected in the present embodiment. FIG. 1 is a side sectional view of a nuclear reactor 1 according to one embodiment.

  As exemplarily shown in FIG. 1, a nuclear reactor 1 according to some embodiments is configured to generate steam by thermal energy generated in a fission reaction. In the embodiment exemplarily shown in FIG. 1, the reactor 1 is a pressurized water reactor (PWR: Pressurized Water Reactor). In other embodiments, the reactor 1 may be a boiling water reactor (BWR), or, unlike light water reactors, including pressurized water reactors and boiling water reactors, moderators or A nuclear reactor of a type using a substance other than light water as a coolant may be used.

The nuclear reactor 1 includes a nuclear reactor vessel 2, a core tank 30, a fuel assembly 15, and control rods 16.
Specifically, the reactor vessel 2 includes a reactor vessel body 3, a reactor vessel body 3, and a reactor vessel lid (upper mirror) 4 that can be opened and closed.
The reactor vessel body 3 has a cylindrical shape whose lower part is closed by a lower mirror 5 having a hemispherical shape. The reactor vessel body 3 has a coolant inlet (inlet nozzle) 6 for supplying light water (coolant) as primary cooling water at an upper portion thereof, and a coolant outlet (outlet nozzle) 7 for discharging light water. Are formed. In addition, the reactor vessel main body 3 is formed with a water injection nozzle (water injection nozzle) not shown separately from the coolant inlet portion 6 and the coolant outlet portion 7.

  Inside the reactor vessel body 3, an upper core support plate 8 is fixed above the coolant inlet 6 and the coolant outlet 7, and the lower core support plate 8 is positioned near the lower mirror 5 below. The plate 9 is fixed. The upper core support plate 8 and the lower core support plate 9 are formed in a disk shape, and have a large number of communication holes (not shown). An upper core plate 11 having a plurality of communication holes (not shown) is connected below the upper core support plate 8 via a plurality of core support columns 10.

  The core tank 30 has a cylindrical shape. The core tank 30 is disposed inside the reactor vessel main body 3 at a predetermined interval from the inner wall surface of the reactor vessel main body 3. The core tank 30 has an upper part connected to the upper core plate 11 and a lower part connected to the lower core plate 12. The lower core plate 12 has a disk shape, and has a large number of communication holes (not shown) formed therein, and is supported by the lower core support plate 9. The outer peripheral side of the core tank 30 may be covered with a heat shield 40 (see FIGS. 2 and 3).

The core 13 is formed by the upper core plate 11, the core tank 30, and the lower core plate 12.
A large number of fuel assemblies 15 and a large number of control rods 16 are arranged inside the core 13. A large number of control rods 16 are grouped at the upper end into a control rod cluster 17 and can be inserted into the fuel assembly 15. A number of control rod cluster guide tubes 18 are fixed to the upper core support plate 8 so as to penetrate the upper core support plate 8. The lower end of each control rod cluster guide tube 18 extends to the control rod cluster 17 in the fuel assembly 15.

  The fuel assembly 15 is supported by a support plate (not shown) with a plurality of fuel rods arranged in a lattice. Fission reactions in a plurality of fuel rods included in the fuel assembly 15 are controlled by a control rod cluster 17 having a plurality of control rods 16. The control rod cluster 17 is driven by a control rod driving device 19 so that a plurality of control rods 16 included in the control rod cluster 17 move up and down inside the fuel assembly 15.

  The reactor vessel lid 4 constituting the reactor vessel 2 has a hemispherical upper part, and is provided with a control rod driving device 19 of a magnetic jack, and is housed in a housing 21 integrated with the reactor vessel lid 4. Have been. The plurality of control rod cluster guide tubes 18 extend at the upper end to a control rod drive device 19, and a control rod cluster drive shaft 20 extended from the control rod drive device 19 passes through the control rod cluster guide tube 18. The control rod cluster 17 extends through the fuel assembly 15 so as to be able to grip the control rod cluster 17. The control rod driving device 19 extends in the vertical direction and is connected to the control rod cluster 17, and controls the output of the reactor 1 by moving the control rod cluster driving shaft 20 up and down.

  In the reactor 1 having the above configuration, the control rod driving device 19 moves the control rod cluster drive shaft 20 to pull out the control rods 16 from the fuel assembly 15 by a predetermined amount, thereby controlling nuclear fission in the core 13. The light energy filled in the reactor vessel 2 is heated by the generated thermal energy, and the high-temperature light water is discharged from the coolant outlet 7 and sent to a steam generator (not shown). That is, the nuclear fuel constituting the fuel assembly 15 emits neutrons by fission, and light water as a moderator and primary cooling water lowers the kinetic energy of the released fast neutrons to thermal neutrons, thereby producing new neutrons. It facilitates nuclear fission and takes away the generated heat for cooling. On the other hand, by inserting the control rods 16 into the fuel assembly 15, the number of neutrons generated in the core 13 is adjusted, and by inserting all the control rods 16 into the fuel assembly 15, the Can be stopped.

  Further, the above-described nuclear reactor 1 may be provided in a nuclear power plant (not shown). The nuclear power plant includes a nuclear reactor 1, a steam turbine driven by steam generated in the nuclear reactor 1, and a generator driven by rotation of a rotating shaft of the steam turbine.

  Here, a specific configuration of the core tank 30 in the embodiment exemplarily shown in FIG. 2 will be described. FIG. 2 is a side view of the core tank 30 according to one embodiment. In FIG. 2, the heat shield 40 is indicated by a broken line.

In one embodiment, the core vessel 30 has a cylindrical shape, and when housed in the reactor vessel 2 (see FIG. 1), the upper flange 31 formed at the upper end of the reactor vessel 30 is attached to the reactor vessel 2. 2 is supported by the reactor vessel 2 (see FIG. 1) by engaging with a step provided on the upper part of the reactor vessel 2 (see FIG. 1).
Specifically, the core tank 30 includes an upper structure portion 32 provided with an upper flange 31, and a cylindrical body portion 33 facing the fuel assembly 15 (see FIG. 1).
As described above, the lower core support plate 9 (see FIG. 1) that supports the load of the fuel assembly 15 (see FIG. 1) is connected to the bottom surface of the core tank 30.

  A cylindrical heat shield 40 is attached to the outer peripheral side of the core tank 30 so as to cover the core tank 30. The thermal shield 40 may be provided so as to cover the body 33 below the upper structure 32 of the core vessel 30. For example, the heat shield 40 is provided below an inlet nozzle 37 (see FIG. 3) or an outlet nozzle 38 provided in the upper structure portion 32. The inlet nozzle 37 or the outlet nozzle 38 is provided corresponding to the coolant inlet 6 and the coolant outlet 7 shown in FIG. In another embodiment, the thermal shield 40 may be provided intermittently in the circumferential direction of the core tank 30. That is, the heat shield 40 may have a configuration in which a plurality of panels are arranged along the outer periphery of the core tank 30 such that the plurality of panels are separated from each other in the circumferential direction.

  The thermal shield 40 is attached to the outer peripheral side of the core tank 30 by at least one pin 45. The at least one pin 45 may be provided radially in an annular gap between the core vessel 30 and the heat shield 40. Further, at least one pin 45 may be provided in an upper part of the annular gap between the core tank 30 and the heat shield 40.

The body part 33 is integrally formed by vertically stacking the upper structure part 32 and the plurality of cylindrical bodies 33A and 33B and welding them to each other. Therefore, welding beads (welding lines) 35A to 35C are formed at the joints between the upper structure portion 32 and the cylindrical bodies 33A and 33B which are vertically adjacent to each other. These weld beads 35 </ b> A to 35 </ b> C are formed along the horizontal direction over the entire circumference of the core vessel 30.
Further, for example, when each of the upper structure portion 32 and the cylindrical bodies 33A and 33B is formed into a cylindrical shape by bending a plate material, the core vessel 30 also includes vertical weld beads 36A to 36C. I have. In the example shown in FIG. 2, the circumferential positions of the weld beads 36A to 36C are shifted from each other, but the circumferential positions of the weld beads 36A to 36C may be the same.

Next, an inspection device 50 of the core tank 30 according to some embodiments will be described with reference to FIGS. FIG. 3 is a perspective view showing a state where the inspection device 50 according to one embodiment is attached to the core tank 30. FIG. 4 is a perspective view illustrating a schematic configuration of the inspection device 50 according to the embodiment. FIG. 5 is a diagram showing a cross section taken along line AA of FIG. FIG. 6 is an enlarged view of a portion B in FIG. FIG. 7 is an enlarged view of a portion C in FIG. FIG. 8 is a side view of the carrier 70 having the counter weight 78 according to one embodiment.
FIG. 3 is a partial cross-sectional perspective view of the heat shield 40, which is partially cut away to show the peripheral structure of the bead sensor 52 and the imaging unit 54 in the inspection device 50. FIG. 6 omits the guide tube 71 to show a rack 72 described later. FIG. 7 is a view of part C (the bead sensor 52 and the imaging unit 54) in FIG.

  In the following embodiment, inspection of the weld beads 35A to 35C extending in the horizontal direction will be exemplarily described. In the following description, “axial direction” refers to the axial direction of the core vessel 30, and “circumferential direction” refers to the circumferential direction of the core vessel 30.

  The inspection device 50 of the core tank 30 exemplarily shown in FIGS. 3 and 4 is for inspecting the weld beads 35A to 35C extending along the circumferential direction of the core tank 30 of the reactor 1 (see FIG. 1). Device. As one embodiment, the illustrated inspection device 50 is configured to inspect the weld beads 35A to 35C on the outer peripheral surface of the core vessel 30.

  In some embodiments, the inspection device 50 of the core tank 30 includes a bead sensor 52, an imaging unit 54, a carrier 70, a first actuator 56, and a second actuator 58.

The bead sensor 52 is configured to detect the weld beads 35A to 35C. For example, as the bead sensor 52, an eddy current sensor, an infrared sensor, or the like is used.
The imaging unit 54 is configured to image the welding beads 35A to 35C. That is, the imaging unit 54 is configured to acquire an image of the inspection region of the core tank 30 including the welding beads 35A to 35C. The images of the weld beads 35A to 35C captured by the image capturing unit 54 are used for visual inspection or used for image analysis.

The carrier 70 is configured to support the bead sensor 52 and the imaging unit 54 and to be movable in the axial and circumferential directions.
The first actuator 56 is configured to move the bead sensor 52 and the imaging unit 54 along the axial direction during detection of the weld beads 35A to 35C by the bead sensor 52.
The second actuator 58 is configured to move the carrier 70 in the circumferential direction at the position where the bead sensor 52 detects the welding beads 35A to 35C during the imaging of the welding beads 35A to 35C by the imaging unit 54.
The specific configuration of the carrier 70, the first actuator 56, and the second actuator 58 will be described later.

The inspection device 50 includes a bead sensor 52 for detecting the weld beads 35A to 35C, and an imaging unit 54 for imaging the weld beads 35A to 35C. The imaging unit 54 images the welding beads 35A to 35C at the detection positions of the welding beads 35A to 35C by the bead sensor 52. Thereby, it is possible to appropriately image the welding beads 35A to 35C without missing the welding beads 35A to 35C even in the core tank 30 whose visibility is reduced due to aging.
A first actuator 56 configured to move the bead sensor 52 and the imaging unit 54 along the axial direction during detection of the weld beads 35A to 35C by the bead sensor 52 as a moving mechanism of the carrier 70; And a second actuator 58 configured to move the carrier 70 in the circumferential direction at the position where the bead sensor 52 detects the welding beads 35A to 35C during imaging of the welding beads 35A to 35C. By detecting the height direction positions of the welding beads 35A to 35C by the bead sensor 52 moved in the axial direction by the first actuator 56, and moving the imaging unit 54 in the circumferential direction by the second actuator 58 at the height position. For example, the long welding beads 35A to 35C extending along the horizontal direction in the core tank 30 are reliably detected and appropriately imaged, for example, the welding beads 35A to 35C extending in the horizontal direction of the core tank 30. can do.

As shown in FIGS. 3 and 4, in some embodiments, the inspection device 50 includes a traveling rail 60 attached to the core tank 30 along the circumferential direction while being positioned with respect to the radial direction of the core tank 30. The carrier 70 is configured to be able to travel along the traveling rail 60.
According to this configuration, the traveling rail 60 attached to the core tank along the circumferential direction is provided in a state positioned in the radial direction of the core tank 30, so that the carrier 70 can be accurately positioned along the traveling rail 60. Can be moved.

The traveling rail 60 may be attached to the upper flange 31 of the core tank 30.
For example, when the inspection of the core tank 30 is performed underwater, the traveling rail 60 can be detached from above the inspection pool, so that the operation of attaching or detaching the traveling rail 60 is simplified. In addition, since the upper flange 31 of the core tank 30 generally extends in the horizontal direction almost exactly, the traveling rail 60 can be properly installed in the horizontal direction by following the upper flange 31.

The traveling rail 60 has a plurality of fitting portions 61 that can be respectively fitted with a plurality of positioning protrusions or recesses formed in the core vessel 30. In the embodiment shown in FIG. 4, a fitting portion 61 protruding downward in the axial direction is provided on the lower surface of the traveling rail 60. On the other hand, although not shown, a concave portion is provided at a position corresponding to the fitting portion 61 on the upper flange 31 (see FIG. 3) of the core vessel 30. Then, by fitting the fitting portion (convex portion) 61 of the traveling rail 60 with the concave portion of the upper flange 31 (see FIG. 3), the traveling rail 60 can be appropriately positioned with respect to the core tank 30. it can.
As described above, when the traveling rail 60 is installed, the protrusion or the concave portion of the core tank 30 (see FIG. 3) is fitted to the fitting portion 61 of the traveling rail 60, so that the core tank 30 (see FIG. 3) is fitted. On the other hand, the traveling rail 60 can be accurately positioned. Accordingly, the carrier 70, the bead sensor 52, and the imaging unit 54 (all shown in FIG. 3) can be appropriately moved.

In the embodiment shown in FIGS. 3 and 4, the running rail 60 includes an annular rail portion 62 that is continuous in the circumferential direction, and at least one bridge portion 63 provided to intersect the annular rail portion 62. .
Specifically, the annular rail portion 62 is formed in an annular shape having a perfect circular shape along the upper flange 31 of the core tank 30. The bridge portion 63 has an end connected to the annular rail portion 62 and extends linearly on the inner peripheral side of the annular rail portion 62. In one embodiment, at least one bridge portion 63 includes a plurality (four in the illustrated example) of bridge portions 63 radially arranged from the central axis O of the core vessel 30 toward the annular rail portion 62. Including.
As described above, since at least one bridge portion 63 is provided so as to intersect with the annular rail portion 62, the strength of the annular rail portion 62 can be secured, and the annular rail portion 62 can be stabilized even when the carrier 70 moves. I can support it.

As shown in FIG. 5, the running rail 60 may further include a rib 65 provided on at least one of the annular rail portion 62 and the bridge portion 63. For example, the rib 65 is formed on the lower surface of the traveling rail 60.
Accordingly, the strength of the annular rail portion 62 can be further improved, so that the annular rail portion 62 bends even under the load of the carrier 70, the bead sensor 52, and the imaging unit 54 (see FIG. 3). Can be prevented, and the carrier 70 (see FIG. 3) can be appropriately moved.

In the embodiment shown in FIGS. 3 and 4, the inspection device 50 is configured such that one end is rotatably fixed to at least one bridge portion 63 on the center (center axis O) of the annular rail portion 62 and the other end is a carrier. The vehicle further includes a travel guide rod 67 connected to 70. For example, one end of the travel guide rod 67 is rotatably attached to the bridge 63 at the center (center axis O) of the annular rail portion 62, and the carrier 70 connected to the other end is annularly mounted around the attachment portion as a fulcrum. It is configured to rotate along the rail portion 62. In this case, the length of the traveling guide rod 67 substantially matches the radius of the annular rail portion 62.
Thereby, the carrier 70 can be accurately positioned in the radial direction of the core tank 30, and the carrier 70 can be appropriately moved on the annular rail portion 62.

  Here, specific configurations of the carrier 70, the first actuator 56, and the second actuator 58 in one embodiment will be described with reference to FIGS. 3, 4, 6, and 7. FIG.

As shown in FIGS. 3, 4 and 6, the carrier 70 is supported by the traveling rail 60 and is configured to move only in the circumferential direction, and the guide tube 71 attached to the fixed frame 79. And
The first actuator 56 and the second actuator 58 are attached to the fixed frame 79.
The guide tube 71 extends in the vertical direction, and is attached to the fixed frame 79 at an upper portion thereof. Further, the guide tube 71 has a hollow structure, and the bead sensor 52 and the imaging unit 54 can pass through the inside of the guide tube 71. As shown in FIG. 7, the bead sensor 52 is connected to a sensor feed cable 53, and the imaging unit 54 is connected to an imaging unit feed cable 55. The sensor feed cable 53 and the imaging unit feed cable 55 are each inserted into the guide tube 71. The sensor feed cable 53 and the imaging unit feed cable 55 are respectively advanced and retracted in the guide tube 71 in the axial direction by the first actuator 56. In this way, the bead sensor 53 and the imaging unit 54 connected to the feed cables 53 and 55 are configured to be movable in the axial direction by the first actuator 56, respectively. As described above, the bead sensor 52 and the imaging unit 54 can be moved in the axial direction via the feed cables 53 and 55 inserted through the guide tube 71, so that the first actuator is located at a position distant from the bead sensor 52 and the imaging unit 54. 56. For this reason, as shown in FIG. 3, the first actuator 56 is installed using the space above the core tank 30 where a relatively easy space can be secured, instead of the narrow space near the bead sensor 52 and the imaging unit 54. Becomes possible.

  As shown in FIG. 6, the first actuator 56 is configured to move the guide tube 71 along the axial direction with respect to the fixed frame 79 by a rack and pinion mechanism. Specifically, a first actuator (for example, a motor) 56 and a pinion 73 rotated by the first actuator 56 are attached to the fixed frame 79. On the other hand, a rack 72 is provided inside the guide tube 71. When the first actuator 56 is driven, the pinion 73 rotates, and the rack 72 meshed with the pinion 73 moves in the axial direction. The rack 72 is connected to the sensor feed cable 53 and the imaging unit feed cable 55, and the bead sensor 52 and the imaging unit 54 are moved in the axial direction with respect to the fixed frame 79 and the guide tube 71 (that is, with respect to the traveling rail 60). It is designed to move. Thus, the bead sensor 52 and the imaging unit 54 are moved in the axial direction by the first actuator 56.

  Further, a reaction force receiving portion 74 for receiving a stress acting on the rack 72 from the first actuator 56 may be provided on the opposite side of the rack 72 from the first actuator 56. The rack 72 to which the rotational power of the first actuator 56 is transmitted is pressed against the side surface of the pinion 73, and an external force is generated on the rack 72 in a direction opposite to the first actuator 56. Therefore, the rack 72 and the feed cables 53 and 55 can be stably moved in the axial direction by providing the reaction force receiving portion 74 for generating a reaction force receiving the external force.

  The second actuator (for example, a motor) 58 is configured to rotate a wheel 75 provided between the fixed frame 79 and the running rail 60 (specifically, the annular rail portion 62). The wheels 75 are rotatably mounted on a fixed frame 79. When the second actuator 58 is driven, the wheels 75 rotate on the traveling rail 60, and the fixed frame 79 moves in the circumferential direction together with the guide tube 71. Thus, the bead sensor 52 and the imaging unit 54 are moved in the circumferential direction by the second actuator 58.

As shown in FIG. 3, the bead sensor 52, the imaging unit 54, and at least a part of the carrier 70 are disposed in a gap between the heat shield 40 provided on the outer peripheral side of the core tank 30 and the core tank 30. It may be configured to be accessible.
Thereby, welding beads 35A to 35C in a narrow portion between core vessel 30 and thermal shield 40 can be reliably detected, and welding beads 35A to 35C can be appropriately imaged.

  For example, the guide tube 71 is provided with a first straight portion 71A provided along the vertical direction, a bent portion 71B provided at the lower end of the first straight portion 71A, and a lower end of the bent portion 71B along the vertical direction. And the second linear portion 71C. The fixed frame 79 is attached to the first straight portion 71A. The bent portion 71B is formed such that the lower end side is located closer to the inner peripheral side than the upper end side in the radial direction of the core vessel 30. Therefore, the second straight portion 71C is located on the inner peripheral side of the first straight portion 71A. Thereby, the bead sensor 52 and the imaging unit 54 can be brought closer to the outer peripheral surface of the core tank 30, and the bead sensor 52 and the imaging unit 54 are smoothly introduced into a narrow portion between the core tank 30 and the heat shield 40. be able to.

Further, the distal end portion of the guide tube 71 formed by the second straight portion 71C has a dimension that can be inserted into the annular gap between the core tank 30 and the heat shield 40. Then, at the time of inspection by the prefectural device 50, the bead sensor 52 and the imaging unit 54 are respectively moved below the distal end portion (second linear portion 71 </ b> C) of the guide tube 71 by feed cables 53 and 55 inserted into the guide tube 71. It is hanging.
Thus, when the bead sensor 52 and the imaging unit 54 are moved into the annular gap along the axial direction by the first actuator 56 as advance preparation for the inspection by the inspection device 50, the bead sensor 52 and the imaging unit 54 are caused to enter the annular gap between the bead sensor 52 and the imaging unit 54. Will be easier.

Further, the inspection device 50 includes a narrow portion inspection carrier for inspecting the weld beads 35A to 35C in the gap between the core tank 30 and the heat shield 40, and a welding in an area not covered by the heat shield. A plurality of types of carriers 70 including a non-narrow portion inspection carrier for inspecting a bead may be configured to be exchangeable. As an example, the narrow portion inspection carrier is configured such that the above-described guide tube 71 includes the first straight portion 71A, the bent portion 71B, and the second straight portion 71C, and the bead sensor 52 and the imaging unit 54 are easily introduced into the narrow portion. It has a configuration. On the other hand, the non-constricted portion inspection carrier is configured such that the guide tube 71 is formed only of a straight portion, so that the distance between the bead sensor 52 and the imaging unit 54 and the outer peripheral surface of the core tank 30 can be secured to some extent. A configuration capable of coping with irregularities on the outer peripheral surface may be adopted.
In this way, by making a plurality of types of carriers 70 including the narrow portion inspection carrier and the non-narrow portion inspection carrier replaceable, an appropriate carrier 70 is selected according to a target portion to be inspected. Most areas can be properly inspected.

In one embodiment, during the movement of the carrier 70 by the second actuator 58, at least one of the first actuators 56 in the gap between the heat shield 40 provided on the outer peripheral side of the core tank 30 and the core tank 30 is provided. When the imaging unit 54 approaches the circumferential position range where the pin 45 is located, the imaging unit 54 (and the bead sensor 52) is moved in the axial direction so that the imaging unit 54 avoids at least one pin 45. Be composed. For example, when the pin 45 is provided above the inspection target area, when the carrier 70 is moved in the circumferential direction by the second actuator 58, the bead sensor 52 and the imaging unit 54 are moved by the first actuator 56 at the position of the pin 45. After the pin 45 is moved above the pin 45, the pin 45 is moved by the second actuator 58 in the circumferential direction to a position where it can be avoided. Then, the bead sensor 52 and the imaging unit 54 are lowered again to the positions of the welding beads 35A to 35C by the first actuator 56 again, and the imaging by the imaging unit 54 is restarted.
Note that the length of the guide tube 71 is preferably set so that the tip of the guide tube 71 is located above the pin 45. In this case, even if the carrier 70 is moved in the circumferential direction, the guide tube 71 and the pin 45 do not interfere with each other. Therefore, only the bead sensor 52 and the imaging unit 54 are raised by the first actuator 56 to avoid the pin 45. Is enough.

  According to this configuration, when the pins 45 are provided on the outer peripheral side of the core tank 30 such as the mounting pins of the heat shield and the guide pins of the upper core plate, the imaging unit 54 avoids the pins 45. By moving the imaging unit 54 (and the bead sensor 52) in the axial direction, the carrier can be moved along the core tank 30 without re-installing the carrier 70 at the position of the pin 45. Therefore, the efficiency of inspection work can be improved.

As shown in FIG. 7, the carrier 70 further includes a fixing member 76 to which the bead sensor 52 and the imaging unit 54 are fixed. The fixing member 76 is provided so as to protrude from an opening at the tip of the guide tube 71. The bead sensor 52 is supported by the fixing member 76 at a position shifted from the imaging unit 54. In FIGS. 3, 4, 8, and 9, the fixing member 76 is omitted.
In the illustrated embodiment, the bead sensor 52 and the imaging unit 54 are attached to the fixing member 76 at positions shifted in the horizontal direction.
In another embodiment (not shown), the bead sensor 52 and the imaging unit 54 may be attached to the fixing member 76 at a position shifted in the vertical direction, or at positions shifted in the horizontal direction and the vertical direction.
According to this configuration, since the positions of the bead sensor 52 and the imaging unit 54 are different, it is possible to monitor (detect or capture) substantially the same surface by adjusting the respective angles.

In the embodiment shown in FIG. 8, the inspection device 50 further includes a counterweight 78 attached to the carrier 70.
At the time of detecting or imaging the weld beads 35A to 35C, the center of gravity of the bead sensor 52 and the imaging unit 54 is located away from the support point P which is the contact point between the traveling rail 60 and the carrier 70. Therefore, the carrier 70 can be moved stably by adjusting the weight balance of the carrier 70 by the counter weight 78.
Specifically, as described above, when the guide tube 71 includes the first straight portion 71A, the bent portion 71B, and the second straight portion 71C, the bead sensor 52 is provided with respect to the support point P of the carrier 70 on the traveling rail 60. and the lower end of the guide tube 71 by the load of the imaging unit 54 acts a moment M ₁ toward the outer peripheral side. Therefore, Bidosensa 52 and moment M ₂ toward the inner peripheral side is generated by providing the counterweight 78 on the outer peripheral side of the imaging unit 54, since these moments M _1, M ₂ are balanced, the guide tube 71 vertical posture Can be held stably.

Next, an inspection method of the core tank 30 will be described with reference to FIG.
In some embodiments, the inspection method of the core tank 30 includes welding beads 35A to 35C (35C is omitted in FIG. 9) extending along the circumferential direction of the core tank 30 of the reactor 1 (see FIG. 1). A method of inspecting, wherein the bead sensor 52 detects the weld beads 35A to 35C while moving the bead sensor 52 in the axial direction of the core tank 30, and an image pickup unit is provided at a detection position of the weld beads 35A to 35C by the bead sensor 52. Imaging the welding beads 35 </ b> A to 35 </ b> C by the imaging unit 54 while moving the projection 54 in the circumferential direction.

According to the inspection method of the core tank, the bead sensor 52 detects the welding beads 35A to 35C while moving the bead sensor 52 in the axial direction of the core tank 30, and the imaging unit 54 is moved in the circumferential direction at the detected position. Meanwhile, the imaging unit 54 images the welding beads 35A to 35C. Thereby, even in the core tank 30 whose visibility has decreased due to aging, the welding beads 35A to 35C can be appropriately imaged without overlooking the welding beads 35A to 35C.
Further, by detecting the height direction positions of the welding beads 35A to 35C by the bead sensor 52 moved in the axial direction of the core tank 30, and by moving the imaging unit 54 in the circumferential direction at the height direction position to perform imaging, For example, long welding beads 35A to 35C extending along the horizontal direction in the core tank 30 are reliably detected and appropriately imaged, such as welding beads 35A to 35C extending in the horizontal direction of the core tank 30. be able to.

Here, an embodiment of the method for inspecting the core tank 30 will be specifically described.
In this inspection method, the weld beads 35A to 35C (35C is omitted in FIG. 9) are inspected with the core tank 30 taken out of the reactor 2 (see FIG. 1) in an upright posture.
First, as shown in FIG. 9A, the traveling rail 60 is attached to the upper flange 31 of the core tank 30. At this time, as shown in FIG. 4, the fitting portion 61 of the traveling rail 60 may be fitted to a concave portion or a convex portion of the upper flange 31 of the core tank 30 for positioning.
Next, as shown in FIG. 9B, the carrier 70 is attached to the annular rail portion 62 of the traveling rail 60. At this time, the bead sensor 52 and the imaging unit 54 are positioned above the heat shield 40.

  Subsequently, as shown in FIG. 9B, the distal end portion (second linear portion 71C) of the guide tube 71 is inserted into the gap between the core tank 30 and the heat shield 40, and the first actuator 56 is driven. Then, the bead sensor 52 and the imaging unit 54 are lowered and sent into the gap between the core tank 30 and the heat shield 40. At this time, the bead sensor 52 detects the weld beads 35A to 35C. Then, at the height direction position detected by the bead sensor 52, the first actuator 56 is stopped, and the imaging unit 54 images the inspection area including the weld beads 35A to 35C. Further, as shown in FIG. 9C, when welding the welding beads 35A to 35C by the imaging unit 54, the bead sensor 52 and the imaging unit 54 are moved in the circumferential direction by the second actuator 58, and a desired inspection target area is obtained. Perform imaging.

When the bead sensor 52 and the imaging unit 54 reach just before the position in the circumferential direction of the pin 45, the first actuator 56 is driven to move the bead sensor 52 and the imaging unit 54 above the pin 45. In this state, the guide tube 71, the bead sensor 52, and the imaging unit 54 are moved in the circumferential direction by the second actuator 58, temporarily stopped at a circumferential position where the pin 45 is not provided, and then bead sensor 52 is again moved by the first actuator 56. Then, the imaging unit 54 is moved downward. At this time, after detecting the height direction positions of the welding beads 35A to 35C again by the bead sensor 52, the imaging units 54 may image the welding beads 35A to 35C. Alternatively, the positions of the previous welding beads 35A to 35C in the height direction may be stored, and the imaging units 54 may image the welding beads 35A to 35C at the stored height positions.
After inspecting the weld beads 35A to 35C continuously or intermittently over the entire circumference of the core vessel 30 and then inspecting the other weld beads 35A to 35C, the bead sensor 52 again detects the weld beads 35A to 35C. The position in the height direction is detected, and the imaging unit 54 images the welding beads 35A to 35C. When the inspection of the weld beads 35A to 35C is completed, the first actuator 56 is driven to move the bead sensor 52 and the imaging unit 54 upward, and then the carrier 70 and the traveling rail 60 are sequentially removed from the core tank 30. .

  As described above, according to at least some embodiments of the present invention, the weld beads 35A to 35C can be appropriately imaged without missing the weld beads 35A to 35C even in the core tank 30 in which the visibility is reduced due to aging. can do. Further, for example, long weld beads 35A to 35C extending along the horizontal direction in the core tank 30 are reliably detected, such as welding beads 35A to 35C extending in the horizontal direction of the core tank 30, and appropriately detected. Images can be taken.

  The present invention is not limited to the above-described embodiment, and includes a form in which the above-described embodiment is modified and a form in which these forms are appropriately combined.

For example, in the above embodiment, the case where the weld bead extending in the horizontal direction is inspected in the core tank as shown in FIG. 2 has been described. Can also be applied.
Further, in the above-described embodiment, the configuration in which the weld beads 35A to 35C are inspected on the outer peripheral surface of the core vessel 30 as shown in FIG. 3 has been described, but the weld bead on the inner peripheral surface of the core vessel 30 is inspected. Is also good.
Furthermore, in the above embodiment, as shown in FIG. 3, the case where the inspection is performed in the gap between the core tank 30 and the heat shield 40 has been described. However, when the heat shield 40 does not exist, or when the heat shield is not provided. The present invention can be applied to an inspection target that is not covered with the body 40.
Furthermore, in the above embodiment, the case where the reactor 1 is a pressurized water reactor as shown in FIG. 2 has been described, but in another embodiment, the reactor 1 may be a boiling water reactor. .

For example, expressions representing relative or absolute arrangement such as “in a certain direction”, “along a certain direction”, “parallel”, “orthogonal”, “center”, “concentric” or “coaxial” are strictly described. Not only does such an arrangement be shown, but also a state of being relatively displaced by an angle or distance that allows the same function to be obtained.
For example, expressions such as "identical", "equal", and "homogeneous", which indicate that things are in the same state, not only represent exactly the same state, but also have a tolerance or a difference to the extent that the same function is obtained. An existing state shall also be represented.
For example, the expression representing a shape such as a square shape or a cylindrical shape not only represents a shape such as a square shape or a cylindrical shape in a strictly geometrical sense, but also an uneven portion or a chamfer as long as the same effect can be obtained. A shape including a part and the like is also represented.
On the other hand, the expression “comprising”, “including”, or “having” one component is not an exclusive expression that excludes the presence of another component.

DESCRIPTION OF SYMBOLS 1 Nuclear reactor 2 Reactor vessel 13 Core 15 Fuel assembly 16 Control rod 30 Core tank 31 Upper flange 32 Upper structure part 33 Body part 33A, 33B Cylindrical bodies 35A to 35C, 36A to 36C Weld beads 40 Thermal shield 45 Pin 50 Inspection device 52 Bead sensor 53 Sensor feed cable 54 Imaging unit 55 Imaging unit feed cable 56 First actuator 58 Second actuator 60 Travel rail 61 Fitting part 62 Ring rail part 63 Bridge part 65 Rib 67 Travel guide rod 70 Carrier 71 Guide pipe 71A First straight portion 71B Bend portion 71C Second straight portion 72 Rack 73 Pinion 74 Reaction force receiving portion 75 Wheels 76 Fixed material 78 Counter weight 79 Fixed frame

Claims (12)

An apparatus for inspecting a weld bead extending along a circumferential direction of a core tank of a nuclear reactor,
A bead sensor for detecting the weld bead,
An imaging unit for imaging the weld bead,
Supporting the bead sensor and the imaging unit, a carrier configured to be movable in the circumferential direction of the core vessel,
During the detection of the weld bead by the bead sensor, a first actuator configured to move the bead sensor and the imaging unit along the axial direction of the core bath,
A second actuator configured to move the carrier in the circumferential direction at a position where the bead sensor detects the weld bead during imaging of the weld bead by the imaging unit;
Equipped with a,
In a state positioned in the radial direction of the core tank, further comprising a traveling rail attached to the core tank along the circumferential direction,
The carrier is configured to be able to travel along the travel rail,
The traveling rail is
An annular rail portion continuous in the circumferential direction,
At least one bridge portion provided so as to cross the annular rail portion,
An inspection apparatus for a core tank , comprising: The inspection apparatus for a core tank according to claim 1 , wherein the traveling rail is attached to an upper flange of the core tank. The running rail, examination of the core barrel according to claim 1 or 2, characterized in that it has a plurality of projections or recesses and the respectively fittable fitting portions for the plurality of positioning formed in the core barrel apparatus. The apparatus according to claim 3 , wherein the traveling rail further includes a rib provided on at least one of the annular rail portion and the bridge portion. Said annular end rotatably on the bridge portion of said at least one on the center of the rail portion is fixed, claims 1, the other end and further comprising a traveling guide rod connected to the carrier 4 The inspection apparatus for a core tank according to any one of the above. The bead sensor, the imaging unit, and at least a part of the carrier are configured to be accessible in a gap between the heat shield provided on the outer peripheral side of the core tank and the core tank. The inspection apparatus for a core tank according to any one of claims 1 to 5 , characterized in that: The inspection device, a narrow portion inspection carrier for inspecting the weld bead in the gap, and a non-narrow portion inspection carrier for inspecting the weld bead in an area not covered by the heat shield. 7. The inspection apparatus for a core tank according to claim 6 , wherein the plurality of carriers are exchangeable. The first actuator is configured such that during movement of the carrier by the second actuator, at least one pin is located in a gap between the heat shield provided on the outer peripheral side of the core tank and the core tank. The image pickup unit is configured to move the image pickup unit in the axial direction so that the image pickup unit avoids the at least one pin when the image pickup unit approaches a directional position range. An inspection apparatus for a core tank according to any one of claims 1 to 7 . The apparatus for inspecting a core tank according to any one of claims 1 to 8 , further comprising a counterweight attached to the carrier. The inspection apparatus for a core tank according to any one of claims 1 to 9 , wherein the bead sensor is supported by the carrier at a position shifted from the imaging unit. A sensor feed cable connected to the bead sensor,
An imaging unit feed cable connected to the imaging unit,
The carrier includes a guide tube through which the sensor feed cable and the imaging unit feed cable are inserted,
The first actuator is configured to advance and retreat the sensor feed cable and the imaging unit feed cable within the guide tube to move the bead sensor and the imaging unit along the axial direction. An inspection apparatus for a core tank according to any one of claims 1 to 10 . The distal end portion of the guide tube is configured to be insertable into a gap between the heat shield and the core tank provided on the outer peripheral side of the core tank,
The said bead sensor and the said image pick-up unit are each suspended below the said front-end | tip part of the said guide pipe | tube by the said sensor feed cable and the said image pick-up unit feed cable which extend inside the said guide pipe | tube. 12. The inspection apparatus for a core tank according to item 11 .

Images