JPS6143676B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an in-core monitor exchange device, particularly an in-core monitor (in-reactor neutron flux measuring device).
This invention relates to an in-core monitor replacement device suitable for removing and installing an in-core monitor from a reactor core.

In-core monitors can be divided into two types, depending on their use: monitors during startup or intermediate times, and monitors during output operation; the former is a traveling type, and the latter is a stationary type. The present invention relates to the latter type of reactor neutron flux measuring device (power range monitor) during power operation.

The core of a nuclear reactor is comprised of a large number of fuel assemblies arranged between a core support and a top guide. Usually, four fuel assemblies are arranged in one grid of the top guide, and a cross-shaped control rod is arranged in the center of the four fuel assemblies. Nuclear reactions in the nuclear reactor are controlled by inserting or withdrawing these control rods. In this way, the core of a nuclear reactor is designed so that there is no wasted space in terms of performance, and the in-core monitors are placed across the narrow spaces. This gap is the space below the lattice plate of the lattice-shaped top guide. If the in-core monitors fail or their performance deteriorates, these in-core monitors must be replaced after removing the reactor pressure vessel top cover during periodic reactor inspections. This replacement work is currently extremely difficult.

The replacement work of a conventional in-core monitor will be explained with reference to FIGS. 1 and 2. In FIG. 1, an in-core monitor 4 inside a reactor pressure vessel 3 is held by a top guide 5 and an in-core flange 6.
The reactor core is sealed by the in-core flange 6 and the seat surface 9 of the tapered part of the in-core monitor 4. 7 is a core support, and 8 is an in-core monitor housing. Conventionally, the approximately 13 m long in-core monitor 4 is handled by operating a fuel exchange trolley 10 and an overhead crane 11. When removing the used in-core monitor 4 from the reactor core,
It is cut to a predetermined length or bent and stored in a spent fuel storage pool (not shown). 1 is the lower reactor room, 2 is the 5th floor of the reactor building (hereinafter referred to as the 5th floor), 16 is the workbench, 17 is the hoist, 18
is an incore monitor handling tool. Reference numeral 19 is a spring reel, which is attached to the operating trolley 21 in the lower reactor chamber 1, and around which the cable 20 is wound. 22
is a pedestal.

In Figure 2, 12 is a strong back;
It is used when inserting a new in-core monitor 4 into the reactor core. Then, attach the in-core monitor 4 to the strong back 12, and
Avoid bending or distortion during handling. In this case, first, the overhead crane 11 lifts the strong bag 12 horizontally using the hook 13 at the middle part, and then the auxiliary hook 14 of the overhead crane 11 lifts the strong bag 12 from the lifting fitting 15 at the tip.
The strong bag 12 is held vertically by operating two hooks of the overhead crane 11.
After that, the hoist 17 is operated from the workbench 16 of the fuel exchange cart 10 to move the Incore monitor 4 from the strong back 12 to the Incore monitor handling tool 1.
The process involves a complicated procedure of re-gripping the tube and inserting it into the reactor core.

As the in-core monitor handling tool 18, JP-A-52
An operating device shown in FIG. 6 of Publication No. 46296 has been proposed. Incore monitor handling tool 1 like this
8, it is extremely difficult to perform both the operations of removing the in-core monitor 4 from the reactor core and attaching it to the reactor core.

SUMMARY OF THE INVENTION An object of the present invention is to provide an in-core monitor replacement device that allows an in-core monitor to be attached to and removed from the reactor core in a short time.

A feature of the present invention is to provide a first operating means for moving substantially horizontally a fixed claw that moves along the guide member in the axial direction of the guide member and a movable claw that clamps the collar of the in-core monitor. The object of the present invention is to provide a second operating means for moving the pawl and the first operating means in the axial direction of the guide member.

The present invention was developed through a detailed study of the operation of attaching and detaching an in-core monitor. The results of the study are explained below.

FIG. 3 is a detailed view of the head of the in-core monitor 4. FIG. A plunger 2 is attached to the head of the incore monitor 4.
3 is inserted. Plug 24 and collar 25A
and 25B are provided on the plunger 23.
The lower end of the plunger 23 is in contact with a coil spring 26 disposed within the head of the in-core monitor 4. FIG. 3 shows a recess 27 in which the plug 24 is provided below the intersection of the grid members of the top guide 5.
The in-core monitor 4 is inserted into the reactor core, and the in-core monitor 4 is shown attached to the reactor core. When removing the in-core monitor 4, move the movable claw 28 of the in-core monitor handling tool 18 (operating device of JP-A-52-46296) to A.
The collar 25A is engaged with the collar 25A at the point.
This is done by lowering the plug a distance l from point A to point B and pulling out the plug 24 from the recess 27. When installing the in-core monitor 4 in the reactor core, it is necessary to move the plug 24 directly below the recess 27 while lowering the collar 25A, which engages the movable claw 28, to point B. Therefore, the position of the movable claw 28 that engages with the collar portion 25A changes depending on whether the in-core monitor 4 is attached or removed.
The distance l between points A and B differs. When the In-core monitor 4 is installed, the upper end of the In-core monitor handling tool 18 comes into contact with the upper end of the installation guide, so the movable claw 28 can be accurately positioned at point B, and the upper end of the plug 24 is placed above the lower end of the top guide 5. With this position, the plug 24 can be easily inserted into the recess 27. However, Incore Monitor 4
When removing the in-core monitor, the in-core monitor handling tool 18 must be lifted up a little so that the movable claw 28 is at the height of point A. At this time, the in-core monitor handling tool 18 is in a suspended state, and the positioning of the movable claw 28 cannot be carried out with high precision, making it difficult to engage the movable claw 28 with the collar portion 25A located at point A. The present invention solves these problems.

An in-core monitor exchange device, which is a preferred embodiment of the present invention, will be explained based on FIGS. 4, 5, and 6. The in-core monitor exchange device 30 is
It consists of an upper support plate 31, a guide rod 34, a cylinder 37 for vertical operation, a cylinder 42 for longitudinal operation, a fixed claw 46, and a movable claw 49. The upper support plate 31 has connection ports 57, 59, 61, and 62 for supplying and exhausting pressurized air for operation to the guide rod 32, the lifting portion 33, and each cylinder. The upper ends of the four pillars 35 are connected to the upper support plate 3
Fixed to 1. The lower ends of the four pillars 35 are bent inward as shown in FIGS. 4 and 5.
The lower end of each support column 35 is joined together. A central support plate 36 and a lower support plate 55 are attached to the column 35 by welding. The lower ends of the four guide rods 34, whose upper ends are attached to the upper support plate 31, pass through the central support plate 36 and are fixed to the lower support plate 55. The central support plate 36 may be fixed to the guide rod 34. A vertical operation cylinder 37 is installed on the central support plate 36. Pipes 38 and 39 for supplying and discharging pressurized air for operation are connected to the vertical operation cylinder 37, and the upper ends of these pipes are connected to connection ports 61 and 62. A piston rod 40, which is attached to a piston (not shown) within the vertical operation cylinder 37, is attached to a bracket 41.

The detailed structure of the lower part of the in-core monitor exchange device 30 will be explained based on FIGS. 7 and 8. The fixing pawl 46 is slidably attached to the guide rod 34 and is further fixed to the lower end of the bracket 41. A cylinder 42 for longitudinal operation and a pair of guides 54 are installed on the fixed claws 46. Pipe lines 43 and 44 for supplying and exhausting pressurized air for operation are connected to connection ports 57 and 59, and further communicated with cylinder 42 for front and rear operation. A pair of guides 5
A movable pawl 49 that slides within the piston rod 45 is attached to a piston rod 45 that is connected to a piston (not shown) in the longitudinal operation cylinder 42 via a connecting member 53. The fixing claw 46 has a notch 47 into which the in-core monitor 4 is inserted. A circular recess 48 is formed on the upper surface of the notch 47 . Further, a U-shaped recess 48 is formed on the lower surface of the notch 47 . Screw hole 5 for inserting the fixing screw of the guide 54
6 is provided on the fixed claw 46. The movable claw 49 is
It has a notch 50 into which the in-core monitor 4 is inserted. A circular recess 51 is provided on the lower surface of the cutout 50. A stepped portion 52 is formed on the side surface of the movable claw 49. This stepped portion 52 is held down by a guide 54.

The replacement work of the in-core monitor 4 will be explained below. After the operation of the boiling water reactor is stopped, the upper cover of the reactor pressure vessel 3 is removed, and cooling water is filled into the reactor well 58 shown in FIG. 11. Four fuel assemblies surrounding the in-core monitor 4 to be replaced, which is disposed within the core section 60, are taken out from the core section 60.

Thereafter, the installer 65 shown in FIG.
The fuel assembly is inserted into the position of the pulled out fuel assembly. That is, the installation guides 66 and 68 of the installation staff 65
is the lattice member intersection part 6 of the lattice-shaped top guide 5.
4 and inserted into the top guide 5 as shown in FIG. A recess 27 into which the plug 24 of the in-core monitor 4 to be replaced is inserted is present below the grid member intersection 64. Installation guide 66
and the upper end of the installation guide 68 are connected by a connecting fitting 70. A hanging fitting 71 is attached to the successive fitting 70. The bottoms of the installation guides 66 and 68 are
It is inserted into the hole of a fuel support fitting 73 attached to the core support (core support plate) 7 and is supported. A guide plate 67 that guides the lower end of the in-core monitor 4 into the in-core monitor housing 8 is provided at the lower part of the installation guide 66 in an inclined state. A mounting confirmation device (eg, a mirror) 72 is provided within the installation guide 68 . An opening 69 is provided in a portion of the installation guide 68 that faces the recess 27 near the mirror 72 .
The installation member 65 is moved by gripping the hanging fitting 71. 63 is a fuel assembly inserted into the reactor core 60.

A hanging member held by the hoist 17 is attached to the upper end of the lifting part 33 of the in-core monitor exchange device 30. Fuel exchange trolley 10 and hoist 1
7 to lower the in-core monitor replacement device 30 within the installation guide 66 until the top guide 5 is completely inserted into the guide rod 32. When the insertion of the top guide 5 into the guide rod 32 is completed,
The positioning of the in-core monitor exchange device 30 is completed. Thereafter, pressurized air is supplied from the conduit 44 into the cylinder 42 for forward and backward operation to push out the piston rod 45 and move the movable pawl 49 in the direction of arrow 74 (FIG. 4). As a result, the portion of the plunger 23 above the collar portion 25A of the in-core monitor 4 disposed within the reactor core portion 60 is inserted into the notch portion 50 of the movable claw 49. The movable claw 49 is moved in advance by supplying pressurized air through the pipe line 39 into the cylinder 37 for vertical operation.
It is adjusted to be located above 5A.
When the plunger 23 is inserted into the notch 50,
Pressurized air is supplied from the pipe line 38 into the vertical operation cylinder 37 to push out the piston rod 40 and lower the fixed claw 46. The upper part of the collar 25A is inserted into the circular recess 51 of the movable claw 49, and further,
The coil spring 26 is compressed and the plunger 23 descends. When the plug 24 is pulled out from the recess 27, the fixing claw 46 stops lowering. The withdrawal of the plug 24 from the recess 27 can be confirmed by looking at the mirror 72. Pressurized air is supplied from the conduit 43 into the cylinder 42 for forward and backward operation, and the movable claw 49 is moved in the opposite direction of the arrow 74, so that the circular recess 51 of the movable claw 49 and the circular recess 48 of the fixed claw 46 are moved. Match. The collar 25B is inserted into the U-shaped recess 48 of the fixed claw 46, and the collar 25A is interposed between the circular recesses 48 and 51. Here, operate the hoist 17 to replace the in-core monitor exchange device 30.
is pulled up and the in-core monitor 4 is taken out from the reactor core section 60.

In this way, when removing the in-core monitor 4 from the reactor core 60, since the in-core monitor replacement device 30 is attached and fixed to the top guide 5,
By operating the vertical operation cylinder 37 and the longitudinal operation cylinder 42, the movable claw 49 can be positioned accurately, and the in-core monitor 4 can be easily removed. Therefore, the time required to remove the in-core monitor 4 is shortened. Positioning of movable pawl 49 is performed by detecting the distance traveled by piston rods 40 and 45. Furthermore, when the piston in the vertical operation cylinder 37 is at the uppermost end, the movable claw 49 is located above the collar 25A, and when the piston in the longitudinal operation cylinder 42 is at the leftmost position in FIG. so that the plunger 23 is inserted into the notch 50 of the claw 49.
The movement of the movable claw 49 may be adjusted in advance. The guide rod 32 may engage the upper end of the installation guide 66.

The in-core monitor 4 pulled out from the reactor core 60 is reversed so that the plug 24 is at the bottom. This is because the plug 24 portion is the most radioactive and has a high radioactivity level. Thereafter, the in-core monitor 4 is moved to a fuel pool (not shown), where it is stored suspended or cut axially.

As described above, a new in-core monitor 4 is installed at the position of the reactor core 60 from which the in-core monitor 4 was removed. This work will be described below.

On the 5th floor floor 2, a new Incore monitor 4 is attached to the strong back 75 shown in FIG.

A plurality of cart carts 77 attached to the frame 76 are connected by a connecting rod 81. Link mechanism 84 is rotatably attached to connecting rods 81 and 82. The gripping mechanism 87 is connected to the link mechanism 84
Attached to the tip of the

Attaching the Incore monitor 4 to the gripping mechanism 87 is as follows:
This is done by setting the position of the movable gripping part 89 of the gripping mechanism 87. That is, when the movable grip part 89 is in the position E in FIG. 16, the in-core monitor 4
is gripped by a gripping mechanism 87. Grasping mechanism 8
When separating the in-core monitor 4 from the in-core monitor 7, move the movable grip portion 89 to the position F in FIG. When the attachment of the in-core monitor 4 to the grip mechanism 87 is completed, the lock pin 91 is inserted into the hole 90 of the protrusion provided in the movable grip part 89, and
Block the movement of 9.

When the in-core monitor 4 is attached to the strong bag 75, the link mechanism 84 is retracted as shown in FIG. This is because if the link mechanism 84 is extended, there is a high possibility that the in-core monitor 4 will be damaged by the operation of vertically standing the strong back 75 to which the in-core monitor 4 is attached as shown in FIG. Therefore, it is better to retract the link mechanism 84 and bring the in-core monitor 4 as close to the frame 76 as possible until the strong bag 75 is vertically erected. This reduces the risk of damage to the in-core monitor 4. At this time, the link mechanism 28 is fixed so as not to open by a lock mechanism (not shown). Since the cart truck 77 and the balance weight 78 are connected by a roller chain 79, by moving the cart truck 77, the position of gripping the head of the in-core monitor 4 attached to the strong bag 75 can be freely changed. incore monitor 4
After the cart is attached to the strong back 75, the cart 7 can be moved by tightening the anti-movement device 80.
7 is fixed to the frame 76.

The strong bag 75 equipped with the Incore monitor 4 is suspended from the auxiliary hook 14 of the overhead crane 11. By moving the auxiliary hook 14, the strong back 75 is moved above the reactor core 60, and the strong back 75 is erected vertically. Next, from the strong back 75 to the fuel exchange trolley 10
The in-core monitor 4 is replaced by the in-core monitor exchange device 30 attached to the hoist 17 of the in-core monitor 4.
At this time, the collar portion 25A of the in-core monitor 4 is present between the circular recesses 48 and 51 of the fixed claw 46 and the movable claw 49, respectively. The lock mechanism (not shown) fixing the link mechanism 84 is removed, and the link mechanism 84 is extended as shown in FIG. Thereby, the in-core monitor exchange device 30 can be easily aligned on the axis of the in-core monitor 4 attached to the strong bag 25. Therefore, the in-core monitor 4 can be moved to the strong back 7 by the operation of the worker on the workbench 16.
5 to the in-core monitor exchange device 30 in a short time and easily.

By driving the hoist 17 and lowering the in-core monitor exchange device 30, the in-core monitor 4 is inserted into the installation guide 66. When the lower end of the in-core monitor 4 comes into contact with the guide 67, the lower end of the in-core monitor 4 descends along the slope of the guide 67, and is eventually inserted into the in-core monitor housing 8 attached to the core support 7. As the in-core monitor exchange device 30 descends, the in-core monitor 4 gradually descends within the in-core monitor housing 8. The lower end of the in-core monitor 4 is connected to the seat surface 9 of the in-core flange 6.
When the in-core monitor exchange device 30 is seated, the drive of the hoist 17 is stopped and the descent of the in-core monitor exchange device 30 is stopped. The guide rod 32 is attached to the top guide 5 as described above. At this time, the position of the collar portion 25A of the in-core monitor 4 is at the same level as point B in FIG. Pressurized air is supplied into the longitudinal operation cylinder 42 to move the movable claw 49 in the direction of the arrow 74 and position the plug 24 directly below the recess 27 .
Next, pressurized air is supplied from the pipe line 39 into the vertical operation cylinder 37, the fixed claw 46 is raised, and the plug 24 is inserted into the recess 27.

Whether the plug 24 of the in-core monitor 4 is completely inserted into the recess 27 is checked using a mirror 28. In other words, a worker on floor 2 on the 5th floor looks at mirror 2.
This can be confirmed by looking at the state of the vicinity of the recess 27 extending into the area 8. The attachment of the in-core monitor 4 to the reactor core 60 is completed. After completion, movable pawl 49 is moved in the opposite direction of arrow 74. The in-core monitor replacement device 30 and the installation gear 65 are removed from the reactor core 60, and four fuel assemblies are loaded around the attached in-core monitor 4.

Even when the in-core monitor 4 is installed in the reactor core 60, the plug 24 and the recess 27 can be positioned with high accuracy, and the installation work can be performed easily. The time required for installation is shortened. The entire replacement process will significantly save time and reduce the risk of exposure for workers.

Further, since the flange portion 25A is always held directly below by the movable claw 49 within the reactor core 60 when the in-core monitor is attached, the plunger 23 bends and the hole 85 into which the plunger 23 of the in-core monitor 4 is inserted is There is no possibility that the plunger 23 would become jammed and the in-core monitor 4 would become impossible to attach to the reactor core 60. When attaching the in-core monitor 4 to the reactor core 60 using the in-core monitor handling tool shown in FIG. 17, there is a risk that the plunger 23 and the hole 85 may be jammed. That is, when the piston rod 88 is lowered by operating the cylinder 86, the link 92 rotates in the direction of arrow 93, and the movable claw 94 holding the collar 25A of the in-core monitor 4 moves in the direction of arrow 95. By this operation, the in-core monitor 4 moves to the recess 27 as shown by the two-dot chain line.
will be moved directly below. After the in-core monitor 4 is seated on the seat surface 9, the in-core monitor 4 is placed in the recess 27.
Until it moves directly below the flange 25A, the flange 25A is pressed by an oblique force in the direction of the arrow 95 due to the oblique movable claw 94. Therefore, the diameter of approx.
The plunger 23, which is about 12 mm in diameter, is bent and comes into contact with the hole 85, which tends to cause galling between the plunger 23 and the hole 85. If the movable claw 94 is placed horizontally at the position indicated by the solid line in FIG. 17, the movable claw 94 will become oblique at the position indicated by the two-dot chain line in the figure, resulting in the above-mentioned danger. In this embodiment, there is no such danger, and the in-core monitor 4 can be replaced reliably.

Conventionally, when installing the in-core monitor 4 in the reactor core,
Due to the accumulation of crud and adhesion of impurities in the reactor pressure vessel 3 to the seal between the seat surface 9 and the in-core flange 6, the seat surface may not be in complete contact with each other, or seat leakage may occur due to damage to the seat surface. It was dangerous. In order to prevent this, a flushing mechanism (not shown) is provided to stop the insertion just before the lower end of the in-core monitor 4 seats on the sealing surface 9, and the seat surface 9 is washed with the flow rate of the reactor water. .

According to the present invention, the replacement work of the in-core monitor can be performed reliably in a short time.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of the conventional In-Core monitor installation work, Figure 2 is an explanatory diagram of the In-Core monitor being attached to a conventional strongback, and Figure 3 is the installation of the In-Core monitor head to the top guide of the reactor core. An explanatory diagram showing the operation, FIG. 4 is a structural diagram of an in-core monitor exchange device which is a preferred embodiment of the present invention, FIG. 5 is a view taken from the − arrow in FIG. 4, and FIG. A view in the direction of arrows, FIG. 7 is a sectional view of FIG. 4,
FIG. 8 is a view taken from the − arrow in FIG. 7, FIG. 9 is a perspective view of the vicinity of the in-core monitor gripping part of the fixed claw shown in FIG. 8, and FIG. 10 is a view of the in-core monitor gripping part of the movable claw shown in FIG. A perspective view of the vicinity, FIG. 11 is an explanatory diagram showing the in-core monitor replacement work using the in-core monitor replacement device shown in FIG. 4, FIG. 12 is a side view of the installation work shown in FIG. 11, and FIG. 14 is a side view of the strong back shown in FIG. 11, and FIG. 15 is a view in the direction of arrow XII in the figure.
16 is an explanatory diagram showing a state in which the link mechanism is viewed from the − cross section of FIG. 14, and FIG. 17 is a sectional view.
The figure is an explanatory diagram showing the operation of a movable claw of a conventional in-core monitor handling tool. 3... Reactor pressure vessel, 4... In-core monitor, 5... Top guide, 17... Hoist, 3
0... Incore monitor exchange device, 31... Upper support plate, 34... Guide rod, 35... Support column, 3
7... Cylinder for vertical operation, 42... Cylinder for longitudinal operation, 46... Fixed claw, 47, 50... Notch, 48, 51... Circular recess, 49... Movable claw, 65... Installation work , 66, 68...Installation guide, 72...Mirror, 75...Strong back.

Claims (1)

[Claims] 1. A support member that engages with the upper end of an installation guide that is inserted into a lattice member that supports the upper part of the fuel assembly in the reactor core and that guides the in-core monitor having a flange portion at the upper part toward the housing or the lattice member. a guide member attached to the support member and extending downward of the support member; a fixed pawl having a notch that fits together; a movable pawl that has a notch that engages with the upper part of the flange of the in-core monitor and clamps the flange together with the fixed pawl; and the guide member together with the fixed pawl. a first operating means that moves in the axial direction of the movable claw and moves the movable pawl in a substantially horizontal direction; and a first operating means that is attached to the support member or the guide member and moves the sliding member in the axial direction of the guide member. An in-core monitor exchange device comprising a second operation means for controlling the in-core monitor.