JPH0820546B2 - In-reactor inspection device - Google Patents

Description

The present invention relates to an in-reactor inspection device for inspecting the inside of a reactor pressure vessel of a boiling water reactor, and particularly to the reactor pressure vessel. The present invention relates to a device that can be inspected without having to attach and detach various devices.

(Prior Art) A conventional example will be described with reference to FIGS. 12 to 14. 12th
FIG. 1 is a cross-sectional view showing a schematic configuration of a boiling water reactor (hereinafter referred to as BWR), in which reference numeral 1 is a reactor pressure vessel. A core support structure 4 that supports the coolant 2 and the core 3 is housed in the reactor pressure vessel 1. The core 3 is composed of a plurality of fuel assemblies and control rods. Reference numeral 4a in the figure
Is the shroud head. The degree of insertion of the control rods into the core 3 is adjusted by the control rod drive mechanism 5, whereby the core power is controlled.

The coolant 2 flows upward in the core 3 and, at that time, is heated by the nuclear reaction heat of the core 3. The heated coolant 2 becomes a two-phase flow state of water and steam and is introduced into the steam separator 6 installed above the core 3. The steam separated in the steam separator 6 is introduced into the steam dryer 7 provided above the steam separator 6 to become dry steam. This dry steam is transferred to a turbine system (not shown) through a main steam pipe 8 connected to the reactor pressure vessel 1 and used for power generation. The steam that has worked is introduced into a condenser (not shown), condensed and liquefied to become condensed water. This condensate is a condensate purification system (not shown)
It is returned to the reactor pressure vessel 1 again via. On the other hand, the separated water is supplied to the lower part of the core 3 again in a state of flowing down the downcomer portion and being mixed with the feed water. The same cycle is repeated thereafter.

By the way, the core support structure 4 has a structure as shown in FIG. Reference numeral 21 in the figure is an upper lattice plate,
The upper grid plate 21 positions the upper portion of the fuel assembly. On the other hand, a core support plate 22 is arranged below the upper grid plate 21, and the core support plate 22 positions the lower part of the fuel assembly. These upper lattice plate 21 and core support plate 22
Is housed in the core shroud 23.

As shown in Fig. 14, the core shroud 23 is
24, an intermediate body 25, and an upper body 25.
Further, in the figure, reference numeral 26 is a vertical welding portion, and reference numeral 27 is a circumferential welding portion. The lower body 24 has a smaller diameter than the middle body 25, and the middle body 25 has a smaller diameter than the upper body 26.

In the above structure, stress corrosion cracking (hereinafter referred to as SCC) may occur in the longitudinal weld portion 27, the circumferential weld portion 28, and in the vicinity of these weld portions due to long-term operation. If operation is continued in the state where such SCC has occurred, it is expected that cracks due to SCC will progress and the core shroud 23 will be damaged. If the core shroud 23 is damaged,
It is expected that the function of supporting the fuel assembly by the upper lattice plate 21 and the core support plate 22 may be deteriorated to hinder the operation of the nuclear reactor, and that a secondary disaster may be induced.
Considering these points, the inspection work of the core shroud 23 as well as the various equipment located in the core part is extremely important.

By the way, the various devices arranged in the reactor pressure vessel 1 are under high radiation dose, and therefore it is impossible for an operator to directly approach the device to perform an inspection. It is necessary to suspend the inspection equipment from above.

For example, there is a case where the inner surface of the core portion of the core shroud 23 is inspected. In this case, a long pole having inspection equipment attached to the tip is inserted from above the reactor pressure vessel 1. At that time, as described above, the upper lattice plate 21 is provided on the upper portion of the core 3, and there is a concern that the upper lattice plate 21 and the pole may interfere with each other. Therefore, in order to ensure good workability, it is necessary to remove the upper lattice plate 21. The removal of the upper lattice plate 21 means the removal of all the fuel assemblies and the control rods, and the attachment / detachment work requires a long time as well as the work. In addition, when it is removed and then reattached, problems such as centering may occur, and if accurate centering is not performed, the insertion characteristics of the control rod may be impaired. Considering these points, removal of the upper lattice plate 21 should be avoided as much as possible.

When inspecting the inside of the furnace by using the pole without removing the upper lattice plate 21, it is necessary to install a turning mechanism at the lower end of the pole. When such a turning mechanism is installed, a long pole serving as a fulcrum of rotation is attached to the center of the core 3, and the pole having the above-mentioned inspection equipment is turned using the pole. Therefore, in this case, it is necessary to remove all the fuel assemblies and control rods without removing the upper lattice plate 21, which makes the work difficult, and the storage of the removed equipment becomes a problem. There is a problem in that workability is poor because it is necessary to constantly monitor turning and vertical movement.

(Problems to be Solved by the Invention) As described above, in the conventional configuration, there is a problem that the inspection work is difficult and the work also takes a long time. It was made based on the points and the purpose is to facilitate the inspection work inside the furnace,
Another object of the present invention is to provide an in-reactor inspection apparatus capable of improving the operating rate of a plant by shortening the time required for work.

[Structure of the Invention] (Means for Solving the Problems) That is, the in-reactor inspection apparatus according to the present invention is arranged in the reactor pressure vessel and above the core to support the upper end of the fuel assembly. An upper support mechanism supported by the lattice of the upper lattice plate, a lower support mechanism supported by a core support plate disposed in the reactor pressure vessel below the core and supporting the lower end of the fuel assembly, A connecting mechanism that connects the upper supporting mechanism and the lower supporting mechanism, a moving mechanism that can move up and down along the connecting mechanism, and that can rotate, and a vertical mechanism that is attached to the moving mechanism and that can be swiveled and extend and contract. And an arm mechanism provided with an inspection mechanism.

(Operation) That is, the upper support mechanism supported by the upper lattice plate, the lower support mechanism supported by the core support plate, the connecting mechanism connecting these upper supporting mechanism and the lower supporting mechanism, and the connecting mechanism moving up and down. It is composed of a movable mechanism that is attached to the movable mechanism, and an arm mechanism that is attached to the movable mechanism, has an inspection mechanism at its tip, and is vertically rotatable and expandable and contractible.

Then, when performing the inspection, remove only the fuel assembly at the place where it is expected to interfere with the inspection work from the core,
Other devices are left as they are. Then, the inspection device is inserted from above the reactor pressure vessel and inserted into the reactor core through an arbitrary lattice of the upper lattice plate. The inspection device is in a state of being supported by the upper grid plate and the core support plate via the upper support mechanism and the lower support mechanism, and then the moving mechanism is moved via the connection mechanism and the inspection attached to the tip of the arm mechanism. The necessary inspection is performed by the mechanism.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 to 11. Incidentally, the same parts as those of the conventional one are designated by the same reference numerals and the description thereof is omitted. FIG. 1 is a perspective view showing the structure of the in-reactor inspection apparatus according to the present embodiment, in which reference numeral 101 is an upper support mechanism. The upper support mechanism 101 is fitted and supported in the lattice 21a of the upper lattice plate 21 from above. On the other hand, a lower support mechanism 102 is supported by the fuel support fitting 22a of the core support plate 22, and a connection mechanism 103 is arranged between the lower support mechanism 102 and the upper support mechanism 101. The connection mechanism 103 includes a pair of guide poles 104 and 105 arranged between the upper support mechanism 101 and the lower support mechanism 102, and a ball screw 106 arranged between the pair of guide poles 104 and 105. It consists of and. A moving mechanism 107 is attached to the connecting mechanism 103 so as to be movable up and down as shown by an arrow a in the drawing and rotatable in a direction shown by an arrow b. The moving mechanism 107 is moved up and down by the rotation of the ball screw 106. . An arm mechanism 108 is attached to the moving mechanism 107, and an inspection mechanism 109 is attached to the tip of the arm mechanism 108. The arm mechanism 108 expands and contracts in the direction indicated by the arrow c in the figure, and is rotatable in the direction indicated by the arrow d. The above is the schematic configuration of the in-reactor inspection apparatus, and the configuration of the upper support mechanism 101 will be described below in order.

FIG. 2 is a perspective view showing the upper support mechanism 101 with a part thereof cut away. Reference numeral 111 in the drawing denotes a case having substantially the same shape and size as the lattice 21a of the upper lattice plate 21. The case 111 fits into the lattice 21a of the upper lattice plate 21 from above. Case 1 above
A swivel gear 112 is arranged in the gear 11, and another gear 113 is meshed with the swivel gear 112.
The rotating shaft 114a of 114 is fixed. In addition, the swing gear 1
Further gear 115 is meshed with 12 and this gear 115
Is fixed to the rotary shaft 116a of the tachometer 116. As shown in FIG. 3, an adapter 117 is fixed below the turning gear 112, and the pair of guide poles 1 is attached to the adapter 117.
04 and 105 are stuck. A bearing 118 is arranged between the adapter 117 and the case 111.
Therefore, by driving the swing motor 114, the gear 11
3, the adapter 117 rotates in the desired direction via the swivel gear 112, which causes the moving mechanism 107 and the arm mechanism 108.
Point in any direction. Reference numeral 119 in the drawing is a nut for fixing the guide poles 104 and 105 to the adapter 117. On the other hand, an elevating motor 120 is arranged above the turning gear 112, and the ball screw 106 is fixed to a rotary shaft 120a of the elevating motor 120. This lifting motor 1
The ball screw 116 is rotated by driving 20 and thereby the moving mechanism 107 is moved up and down.

Next, the configuration of the moving mechanism 107 will be described with reference to FIGS. 4 and 5. Reference numeral 121 in the drawing is a case slightly smaller than the case 111 of the upper support mechanism 101, and the pair of guide poles 104 and 105 and the ball screw 106 are included in the case 121.
Through holes 122, 123, and 124 are formed respectively. Slide tubes 125 and 126 are mounted in the through holes 122 and 123, respectively. On the other hand, a ball screw nut 127 is arranged below the through hole 124, and the ball nut 127 is fixed to the inner surface side of the case 121 by a bolt or the like not shown. Attach the ball screw 106 to the ball nut 127.
Are screwed together. Therefore, when the ball screw 106 rotates in a desired direction, the case 121 moves up and down via the ball nut 127. Hydraulic cylinder mechanism in the case 121
128 is accommodated and arranged, and the hydraulic cylinder mechanism 128 turns the arm mechanism 108. Also above case 1
A recess 129 is formed on one side of the recess 21, and the arm mechanism 108 is attached to the recess 129. Underwater lights 130 and 131 are arranged on both sides of the recess 129, respectively.

Next, the structure of the arm mechanism 108 will be described with reference to FIG. First, the arm mechanism 108 by the cylinder mechanism 128 described above.
This is the turning of the arm mechanism, as shown in the figure.
A lever 132 is attached to the base end of 108, and this lever 132
Shaft 128a connected to the piston of cylinder mechanism 128
Are connected. Therefore, if the shaft 128a is pulled by the cylinder mechanism 128, as shown by the chain double-dashed line in the figure, the lever 132
The arm mechanism 108 turns downward via. In this state, the projected area from the upper surface is smaller than that of the case 111 of the upper support mechanism 101, so that the lattice 21a of the upper lattice plate 21 can easily pass through. On the contrary, the cylinder mechanism 128
When the shaft 128a is projected by the arm mechanism 108, the arm mechanism 108 pivots to the position shown by the solid line in the figure via the lever 132. In this way, when inserting the inspection device into the core, the arm mechanism 108 is swung to the position shown by the chain double-dashed line in the figure, thereby preventing interference with the upper lattice plate 21. On the other hand, when performing the in-furnace inspection, the arm mechanism 108 is rotated to the position shown by the solid line in the figure.

Next, the configuration of the arm mechanism 108 will be described in more detail with reference to FIG. First, the arm mechanism 108 includes a main arm 141, a telescopic arm 142 whose one end is supported by the main arm 141 and can retract from the main arm 141, a spring box 143 attached to the end of the telescopic arm 142, and the spring box 143. The inspection device 109 fixed to the tip of the. A drive motor 144 is arranged inside the base end portion of the main arm 141, and a gear 145 is fixed to a rotary shaft 144a of the drive motor 144. Another gear 146 meshes with this gear 145, and a ball screw 147 is fixed to this gear 146. This ball screw 147 is the main arm
The inside of 141 is extended in the axial direction. Ball screw 1 above
A ball nut 148 is screwed onto the 47, and the ball nut 148 is fixed to the flange portion 141a in the main arm 141. On the other hand, another ball nut 149 is screwed into the hole screw 147.
It is fixed to the base end of. Therefore, the drive motor
By driving 144, the ball screw 147 rotates via the gears 145 and 146, and the rotation of the ball screw 147 causes the telescopic arm 142 to project from and retract into the main arm 141 via the ball nut 149. The amount of protrusion of the telescopic arm 142 is restricted by the flange 142a formed at the end of the telescopic arm 142 engaging the flange 141b formed at the tip of the main arm 141. Above spring box 143
A spring 150 is housed therein, while an action portion 151 protruding from the telescopic arm 142 is housed in the spring box 143. That is, the above spring 150
Due to this, a certain degree of freedom is ensured. A proximity sensor 192 is attached to the tip of the telescopic arm 142, and the proximity sensor 192 measures the distance from the spring box 143. This proximity sensor 192
The drive motor 144 is rotated in a desired direction on the basis of the measurement result of 1, and thereby the telescopic arm 142 is telescopically extended. This corresponds to the case where the distance between the inspection device and the inspection object changes as shown in FIG.
Incidentally, the structure inside the spring box 143 and the inspection device 1
The mounting structure of 09 will be described later.

Next, the structure of the lower support mechanism 102 will be described with reference to FIG. In the figure, reference numeral 61 is a disc-shaped substrate.
The ball screw 106 is rotatably supported at the center of 61 via a nut 161. The pair of guide poles
104 and 105 are fixed to rotating rings 163 and 164 mounted on the substrate 161. A bearing 165 is arranged between the rotating rings 163 and 164 and the substrate 161. Further, four guides 166 are provided on the lower surface side of the substrate 161, and these four guides 166 are fitted into the recesses 22b of the fuel support fitting 22a.

Next, with reference to FIGS. 10 and 11, the internal structure of the spring box 143 and the mounting structure of the inspection device 109 will be described in detail. On the inspection device 109 side of the spring 150 in the spring box 143, a pair of partition plates 171 and 1 are provided.
A chamber 173 is formed by 72, and a rotary plate 175 is accommodated in the chamber 173. A shaft 176 is projected from the rotary plate 175, and the shaft 176 is inserted into the chamber 173.
An oil seal 177 is mounted between the shaft 176 and the penetrating portions of the partition plates 171 and 172, and the shaft 176 is rotatably supported by the pair of partition plates 171 and 172. One end of a spring 178 made of a shape memory alloy is attached to the shaft 176, and the other end of the spring 178 is fixed to the inner surface of the spring box 143. The spring 178 can be appropriately energized via a cable 179, and the energization causes the shape memory effect to be exerted to adjust the elastic force of the spring 178.
On the other hand, one end of another spring 180 is fixed to the shaft 176, and the other end of the spring 180 is attached to the spring box 143.
It is fixed to the inner surface of the. The spring 178 is energized to exert its shape memory effect to change its elastic force, thereby adjusting the balance of the elastic forces of the springs 178 and 180. By adjusting such balance
The rotating plate 175 rotates via the 176. In the case of the present embodiment, the rotary plate 175 rotates within a range of 90 °, whereby a plurality of ultrasonic waves described later are respectively used for flaw detection on the circumferential welding line or flaw detection on the longitudinal welding line. Align the position of the probe 182. The 90 ° rotation range is restricted by a stopper (not shown). Also above axis
The oil seal 177 is installed in the penetrating portions of the partition plates 171 and 172 of 176 because it is necessary to make the inside of the upper chamber 173 air-tight in relation to energizing the spring 17.

On the other hand, the inspection device 109 is attached to the rotary plate 175 via four springs 181, and the four springs 181 also ensure the degree of freedom. The inspection device 109 also integrally rotates via the spring 181 by the rotation of the rotary plate 175. A plurality of ultrasonic probes 182 are attached to the inspection device 109 via a spring 183, and the spring 183 is installed in the inspection device 1
It is mounted in the recess 184 formed in 09. The ultrasonic probe 182 needs to be pressed perpendicularly to the member to be inspected, and this is ensured by the springs 181 and 1
83. A plurality of ultrasonic probes 182 are installed in the state shown in the figure because the welding line is sandwiched between them and the welding line and its vicinity are to be inspected together. still,
Reference numeral 191 in FIG. 7 is an underwater TV camera.

The operation will be described based on the above configuration. First, remove the fuel assemblies and control rods at the location to be inspected.
Then, the in-reactor inspection device is carried into the reactor pressure vessel 1 by using an unillustrated overhead crane or the like. At this time, the cylinder mechanism 28 is driven and the arm mechanism 108 is swung to the lower side so that the arm mechanism 108 and the core upper part mechanism 21 can be prevented from interfering with each other. In such a state, the inspection device is loaded into the core 3 through the lattice 21a of the upper lattice plate 21. Then, the lower support mechanism 102 of the inspection device is
While being fitted to the fuel support metal fitting 22a from above, the upper support mechanism 101 is fitted to the lattice 21a of the upper lattice plate 21 from above, whereby the inspection device is supported and its position is fixed.

Next, the inspection is started. First, the cylinder mechanism 28 is driven to rotate the arm mechanism 108 in the horizontal direction. At the same time, the underwater lights 130 and 131 are turned on. In this state, the moving mechanism 107 is moved up and down and turned, and the arm mechanism 108 is expanded and contracted to perform a desired inspection, for example, a welding line (first
4 The probe 184 along the welding line indicated by reference numerals 27 and 28 in FIG.
Is scanned to perform flaw detection inspection.

The flaw inspection is first performed from the circumferential welded portion 28. That is, by driving the turning motor 114, the adapter 117 is rotated via the gear 113 and the turning gear 112, and thereby the moving mechanism 107 and the arm mechanism 108 are turned via the pair of guide poles 104 and 105. At this time, as shown in FIG. 8, since the distance between the inspection device 109 attached to the tip of the arm mechanism 108 and the reactor internal structure changes, it is necessary to expand and contract the arm mechanism 108 according to the change in the distance. . This is a spring box 143 due to the proximity sensor 192.
And the drive motor 144 based on the measured value.
Forward or reverse. Thereby ball screw 14
The expansion and contraction arm 142 of the arm mechanism 108 is expanded and contracted via the 7 and the ball nut 149. On the other hand, the turning angle is measured by the tachometer 116, and the flaw detection is stopped by checking the set value (when it is confirmed that the turning angle is a predetermined angle).

Next, the longitudinal welding line 27 is subjected to flaw detection. In this case, the spring 178 is energized via the cable 179 to exert a shape memory effect, thereby changing the balance of the elastic forces of the springs 178 and 180, thereby causing the shaft 176 to move.
Rotate 0 °. As a result, the probe 182 attached to the tip surface of the inspection device 109 also rotates 90 °. In this state, the vertical welding line 28 is monitored while being monitored by the underwater TV camera 191.
The elevating motor 120 is driven to scan the probe 182 along. Also in this case, the flaw detection inspection is stopped after the predetermined inspection is completed.

Then, after all the inspections are completed, the cylinder mechanism is
The arm mechanism 108 is swung downward by the 28 to bring it into the same state as when the inspection device was loaded. In such a state, the inspection device is carried out from the reactor pressure vessel 1 by using the overhead crane, and the fuel assemblies and the control rods which have been removed before the inspection are carried in.

According to this embodiment, the following effects can be obtained.

First, in-core inspection can be performed without removing the upper lattice plate 21 and without removing all fuel assemblies and control rods. That is, it is only the fuel assemblies and control rods that are placed at the positions expected to interfere with the inspection that need to be removed from the core prior to the inspection, and these fuel assemblies and control rods must be removed. Then, after that, the inspection device can be carried into the core through the lattice 21a of the upper lattice plate 21 and necessary inspection can be performed. Therefore, the inspection work is greatly facilitated and the time required for the inspection is greatly reduced, which is extremely effective in improving the plant operating rate and reducing the radiation exposure of workers.

Next, the upper supporting mechanism 101 of the inspection device is provided with a case 111 having the same shape as the lattice 21a of the upper lattice plate 21, and the upper side of the inspection device is supported only by fitting the case 111 to the lattice 21a from above. And positioning is performed. Similarly, the lower end of the inspection device is positioned and supported by fitting the guide 166 of the lower support mechanism 102 into the fitting hole 22b of the fuel support fitting 22a of the core support plate 22 from above.
In this way, the positioning and support of the inspection device is surely performed. And the supporting and positioning of these is facilitated simply by inserting the inspection device from the grid 21a.

Next, the arm mechanism 108 in the present embodiment is provided with the proximity sensor 191.
It is configured to automatically expand and contract based on the measurement result of the distance measurement by, so that, for example, when the flaw is applied to the circumferential welding line 27, the distance between the inspection device 109 and the reactor internal structure to be inspected. Even when the change occurs, the inspection device 109 can be positioned at an appropriate place by expanding and contracting according to the change. Therefore, it is possible to perform highly accurate inspection and to maintain the soundness of the devices including the inspection device 109.

Further, the inspection device 109 according to the present embodiment is rotatable,
Therefore, once mounted, the circumferential welding line 27 and the vertical welding line 28 can be flaw-detected simply by rotating the welding line 27.

The present invention is not limited to the above-mentioned one embodiment. For example, in the above-mentioned one embodiment, an example in which the inspection device 109 is configured as the UT device of the core shroud 4 is shown, but the present invention is not limited to this. , Upper lattice plate 21, core support plate 22,
Alternatively, it may be configured as a fuel assembly inspection device.
It can also be used for visual inspection with the underwater TV camera 191 or the like, or other nondestructive inspection.

[Effects of the Invention] As described in detail above, according to the in-reactor inspection apparatus of the present invention, not only the upper lattice plate but also the fuel assembly and the control rods can be inspected by only partially removing them. And the inspection work is greatly facilitated, and the time required for the inspection is greatly shortened, the operating rate of the plant can be improved, and the radiation exposure of workers can be reduced. The effect is great.

[Brief description of drawings]

1 to 11 are views showing an embodiment of the present invention.
FIG. 1 is a perspective view of the in-reactor inspection apparatus, FIG. 2 is a perspective view showing a part of the upper support mechanism in a cutaway view, FIG. 3 is a sectional view of the upper support mechanism, and FIG. 5 is a perspective view, FIG. 5 is a partial cross-sectional view of the moving mechanism, FIG. 6 is a view showing the swiveling action of the arm mechanism, FIG. 7 is a cross-sectional view of the arm mechanism, and FIG. 8 is a diagram showing the action of the arm mechanism. 9 is a cross-sectional view of the lower support mechanism, FIG. 10 is a perspective view of the inspection device, the rotating plate, and the shaft,
FIG. 11 is a sectional view of the spring box, FIGS.
FIG. 12 is a view used for explaining a conventional example, FIG. 12 is a sectional view of a boiling water reactor, FIG. 13 is a front view of a core support mechanism, and FIG. 14 is a perspective view of a core shroud. 1 ... Reactor pressure vessel, 2 ... Coolant, 3 ... Reactor core, 4
...... Core support mechanism, 2 …… Upper lattice plate, 22 …… Core support plate, 23 …… Core shroud, 101 …… Upper support mechanism, 12
...... Lower support mechanism, 103 ...... Connection mechanism, 107 ...... Movement mechanism, 108 …… Arm mechanism, 109 …… Inspection device.

Claims (3)

[Claims] 1. An upper support mechanism, which is supported by a lattice of an upper lattice plate that is disposed in the reactor pressure vessel and above the core and supports the upper end portion of the fuel assembly, and in the reactor pressure vessel. A lower support mechanism supported by a core support plate that supports the lower end of the fuel assembly and that is disposed below the core, and a connection mechanism that connects the upper support mechanism and the lower support mechanism, and along this connection mechanism An in-reactor inspecting apparatus comprising: a moving mechanism that can move up and down and rotate; and an arm mechanism that is attached to the moving mechanism and that can swivel in a vertical direction and that is expandable and contractible and has an inspection mechanism at a tip thereof. . 2. The in-reactor inspection according to claim 1, wherein the arm mechanism measures a distance from a member to be inspected and expands and contracts based on the measurement result. apparatus. 3. The inspection mechanism is provided with a plurality of ultrasonic probes on the tip surface thereof, and the relative position of the ultrasonic probes can be rotated with respect to the axis of the arm mechanism. The nuclear reactor inspection apparatus according to claim 1.