JP2000298188A - Sealing device for in-core instrumentation guide pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sealing device for an in-core instrumentation guide pipe, having a high sealing function, facilitating insertion and withdrawal of the in-core guide pipe, and preventing interference with other in-core equipment, etc. SOLUTION: In this in-core guide pipe sealing device freely removably inserted into an in-core guide pipe 2 provided on a core support plate 12 below an upper grid plate 8 in a reactor pressure vessel to seal the inside of the in- core guide pipe 2 in a watertight condition, a closure plug 36 having cylindrical sealing packing 46 is inserted into an insertion portion 37 inserted into the in-core guide pipe 2 so as to seal the inside of the in-core guide pipe 2 in a watertight condition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seal device for an in-core guide tube, and more particularly to a seal device for an in-core guide tube which is inserted into an in-core guide tube after a plurality of neutron measurement tubes provided in a core of a boiling water reactor or the like are pulled out. And a sealing device for an in-core guide tube for sealing the inside thereof in a watertight manner.

[0002]

2. Description of the Related Art Generally, in a boiling water reactor, a neutron instrumentation system installed in a reactor core is installed in order to monitor reactor safety, maintain fuel integrity, and achieve efficient combustion. The reactor is operated by measuring neutrons in the reactor with detectors and automatically controlling the power in the reactor based on the measurement data and the like in the central control room.

[0003] The detector of the neutron instrumentation system is called an in-core monitor or a neutron measuring tube, and is referred to as a neutron measuring tube in the present specification. The neutron measurement tube 1
Is referred to as an in-core guide tube.

FIG. 6 shows a state in which the neutron measuring tube 1 is attached to an in-core guide tube 2 in a reactor pressure vessel. That is, the neutron measuring tube 1 has a neutron detector (not shown) for measuring neutrons therein, and the lower half thereof is axially penetrated through both the inside of the in-core guide tube 2 and the inside of the in-core housing 3. Thus, a plurality of lead wires 5 are extended downward from the lower mirror portion 4 of the reactor pressure vessel to the outside and the lower end thereof.

[0005] The neutron measuring tube 1 is provided with a spindle 7 concentrically provided in the upper part thereof, which is axially expandable and contractable by a spring 6.
It is supported by being fitted into a supporting recess 9 on the lower surface of the intersection 8a between the two. The axis of the neutron measuring tube 1 is maintained by guide rings 10 and 11 provided in portions accommodated in the in-core guide tube 2 and the in-core housing 3, respectively.

On the other hand, the in-core guide tube 2 is fixed by inserting an upper end portion of the opening into an insertion hole of the core support plate 12.
An in-core housing 3 is concentrically fixed to the lower end by welding. The incore housing 3 has the incore flange 13 fastened by mounting bolts 14, and the neutron measuring tube 1 penetrates through the incore flange 13 and is mounted with a tightening nut 15. The neutron measuring tube 1 leads from the center hole of the tightening nut 15. The wire 5 is drawn out.

[0007] Each neutron measuring tube 1 constructed as described above is exchanged in order to be updated at every periodic inspection.
During this operation, it is necessary to check and confirm the soundness of the in-core guide tube 2 and the in-core housing 3 after the neutron measurement tube 1 has been pulled out. Further, in recent years, the inspection and reinforcement work of the furnace internal structure at the time of periodic inspection has increased, and the frequency of use of the space as an operation area between the upper lattice plate 8 and the core support plate 12 has increased.

[0008]

To this end, an in-core guide tube sealing device is inserted into the in-core guide tube 2 from the open end thereof to seal the inside of the in-core guide tube 2 in a water-tight manner, and the reactor water is supplied to the in-core guide tube 2. It is necessary to prevent leakage from the upper end of the guide tube 2 into the inside of the guide tube 2 and drain the water from the in-core housing 3 in a water-stopped state, and then check the soundness and the like thereof.

At that time, the most important problem is that the sealing function of the in-core guide tube sealing device is high and reliable, and it is required that the in-core guide tube 2 can be easily inserted into and pulled out of the in-core guide tube 2. There is.

Further, the space from the insertion portion of the in-core guide tube sealing device to be inserted into the in-core guide tube 2 to the upper lattice plate 8 interferes with inspection equipment, reinforcing equipment, and the like used below the upper lattice plate 8 as much as possible. If not considered, parallel work can be performed, and the periodic inspection work will be shortened. Further, since the work is performed in the reactor water in a narrow place in the nuclear reactor, there is a problem that it is required to securely and reliably perform the installation and removal of the in-core guide tube sealing device at the same time every hour.

In recent years, in order to extend the life of the reactor, repair techniques for equipment inside the reactor have been advanced, and construction such as internal inspection, reinforcement, and repair of shrouds and pressure vessels has been performed. . However, the conventional sealing device for the in-core guide tube that stands up from the upper lattice plate to the core support plate interferes with other repair work equipment, and in that case, it is necessary to temporarily remove it. There is a need for such measures.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems and to satisfy the above-mentioned demands. The purpose of the present invention is to provide a high sealing function, easy insertion and withdrawal from an in-core guide tube, and other furnaces. It is an object of the present invention to provide a sealing device for an in-core instrumentation guide tube which does not cause interference with equipment and the like.

[0013]

According to a first aspect of the present invention, a core instrumentation guide tube is mounted on a core support plate provided in a reactor pressure vessel, and is inserted into and removed from the core guide tube. A sealing device for an in-core instrumentation pipe that is inserted to seal the in-core instrumentation guide tube in a water-tight manner, comprising a closing plug for sealing the inside of the in-core instrumentation guide tube in a water-tight manner, the closing plug including a seal box, A seal shaft having a seal portion that is screwed into the seal box and inserted into the in-furnace instrumentation guide tube to seal in a watertight manner, and the seal portion is expanded in diameter when inserted into the in-furnace instrumentation guide tube. And a cylindrical elastic seal packing that is in water-tight contact with the inner surface of the in-furnace instrumentation guide tube.

According to the first aspect of the present invention, at the insertion portion inserted into the in-core guide tube of the in-core guide tube seal device, the other in-core guide tube seal device can be recovered while leaving only the closing plug. It does not interfere with the use of the in-furnace inspection device, and the period of the periodic inspection can be shortened easily. Also,
By fixing the seal packing to the tip of the closing plug with a tapered cap nut, the insertability into the in-core guide tube insertion portion is improved.

Furthermore, by providing a seat that sits on the core support plate when the tip of the closing plug is inserted into the incore guide tube insertion portion, the seal shaft is lengthened so that the insertion portion can be inserted into the incore guide tube. The amount of insertion can be adjusted to an appropriate amount, and the elastic seal packing can be installed at a position separated from the high-dose part.

According to a second aspect of the present invention, the seal box has a pin protruding from an outer surface, the pin is supported by a holder having a dovetail groove into which the pin is inserted, and the seal shaft is screwed with a short wrench from the upper surface. And the short wrench is connected to a lower shaft.

According to the second aspect of the present invention, the tightening torque can be controlled by turning the sealing shaft of the insertion portion of the in-core guide tube sealing device with a wrench from above the fuel exchanger using a wrench, and the degree of compressive deformation can be controlled. And the reliability of the seal is improved.

According to a third aspect of the present invention, the lower shaft is connected via a gear to an intermediate shaft penetrating an upper lattice plate provided in the reactor pressure vessel, and the intermediate shaft projects from an operation floor. Connected to the upper shaft through a gear.

According to the third aspect of the present invention, in the incore guide tube sealing device, the wrench is provided with an upper lattice plate guide,
Since it is suspended in the reactor, the in-core guide tube sealing device can be easily and reliably inserted into a predetermined in-core guide tube, and can be easily removed.

According to a fourth aspect of the present invention, there is provided a cap having an upper end closed to cover an upper end of an in-furnace instrumentation guide tube,
A seal box which surrounds the outside of the cap and is screwed together, and is provided between the inside of the lower part of the seal box and the upper outer surface of the in-furnace instrumentation guide tube and is pressed and supported by the lower end surface of the cap. And a cylindrical elastic seal packing.

According to the fourth aspect of the present invention, the upper grid plate and the core support plate are replaced by a sealing work, so that the cap or the seal box can be replaced by a wrench even if the upper lattice plate and the core support plate are not provided. By rotating the seal member, the seal member can be compressed and deformed, and the seal member can be brought into close contact with the outer surface of the in-core guide tube.

According to a fifth aspect of the present invention, a pin is provided on the seal box, a holder having a dovetail groove into which the pin is inserted is provided, an external wrench is connected to the holder, and the external wrench is provided above the cap. It is characterized by connecting an inner wrench to be inserted into the inside.

According to the fifth aspect of the present invention, a cylindrical outer wrench and an inner wrench are provided as guides to be inserted into the in-core guide tube, so that the in-core guide tube does not interfere with the core support plate and thus has a cylindrical seal. Packing can be compressed. By changing the lengths of the inner wrench and the outer wrench, the wrench can be used as a closure for the incore housing installed below the incore guide tube.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of a sealing device for an in-core instrumentation guide tube according to the present invention will be described with reference to FIGS. FIG. 1 is a longitudinal sectional view showing a sealing device for an in-core instrumentation guide tube according to a first embodiment, partially cut away, and FIG. 2 is a top view as seen from the direction of arrows AA in FIG. 3 (a) is a top view showing a state where a seal box is inserted into the seal shaft in FIG. 1, (b) is a longitudinal sectional view showing a part of the side in (a), and FIG. 4 is a view of the closing plug in FIG. It is a side view which shows a use example partially.

A sealing device for an instrumentation tube in a furnace according to the present embodiment,
That is, the in-core guide tube sealing device 21 is inserted into the insertion portion 32 of the in-core guide tube 2 attached to the core support plate 12 to close the inner surface in a water-tight manner as shown in FIG.
Mainly 36. The closing plug 36 is provided with a seal box 41 as shown in an enlarged view in FIG.
Seal shaft 40 with seal 42 threaded into it
It consists of

The seal shaft 40 is composed of a horizontal member 40a and a vertical member 40b. The Teflon sheet 43, the ring 44, the O-ring 45, the cylindrical seal packing 46, the Teflon sheet 47 and the cap nut 48 are provided on the outer surface of the vertical member 40b. Are provided one above the other to form a seal portion. Seal part 42
Is inserted into the insertion portion in the in-core guide tube 2. Note that Teflon is a tetrafluoroethylene resin, and is a trade name.

The upper lattice plate 8 is provided with an upper gear housing 23 having a guide 22 on the lower surface. A first gear 29 and a second gear 30 are provided in the upper gear housing 23,
An upper shaft 28 is mounted on the first gear 29, and an intermediate shaft 31 is mounted on the second gear 30.

The guide 22 has a pair of leg portions 22 branched into two branches.
a, 22b, and is suspended by inserting the intersection 8a of the upper lattice plate 8 into the crotch between the legs 22a, 22b. The intermediate pipe 24 is fixed. The intermediate pipe 24 extends vertically downward, and a lower gear housing 25 is fixed to a lower end surface thereof.

In the upper gear housing 23, a fuel exchange wire 26 (hereinafter, referred to as fuel exchange, not shown) on the operation floor is fitted to a suspension ear 27 at the upper part of the upper gear housing 23, and the incore guide tube is provided. The sealing device 21 is suspended.

The first and second gears 29 and 30 described above are housed in the upper gear housing 23, and the upper shaft extends from the refueling machine to the center of the intersection 8a between the upper lattice plates 8. A first gear 29 rotated by 28 and a second gear 30 in which the center of the intersection 8a between the upper lattice plates 8 is offset are incorporated.

The intermediate shaft 31 connected to the second gear
Extends downward in the intermediate pipe 24 on the side surface of the guide 22 and is connected to a third gear 32 in the lower gear housing 25. The third gear 32 in the lower gear housing 25 includes a fourth gear 33
The fourth gear 33 is connected to the lower shaft 34 at a position below the vertical line of the center of the intersection 8a between the upper lattice plates 8 and meshes with the lower shaft 34.

That is, as shown in FIG.
And the in-core guide tube 2 is located below the perpendicular of the center of the intersection 8a between the upper lattice plates 8, so that the intermediate pipe 24 is disposed on the side of the guide 22, as shown in FIG. It is offset so as not to interfere with the portion 8a. At the tip of the lower shaft 34, a holder 35 is provided. A closing plug 36 is attached to this holder 35 and suspended in the in-core guide tube 2.

As shown in FIG. 1, after the guide 22 of the in-core guide tube sealing device 21 suspended by the insulated wire 26 reaches the vicinity of the upper lattice plate 8, the guide 22 is connected to the intersection 8a.
, And further lowered, the cylindrical seal packing 46 of the closing plug 36 attached to the holder 35 and the cap nut 48
Is guided to the insertion portion 37 of the in-core guide tube 2, and the seal box 41 of the closing plug 36 is seated on the core support plate 12.

When the closing plug 36 is seated on the core support plate 12 of the insertion portion 37 guided by the guide 22, the in-core guide tube
The operator on the refueling machine rotates the upper shaft 28 in the tightening direction. The rotation of the upper shaft 28 transmits the rotation to the first gear 29, and the first gear 29 held by bearings 38 provided above and below the upper gear housing 23 transmits the rotation to the second gear 30.

The intermediate shaft 31 fixed to the second gear 30 and held by the bearings 38 of the upper gear housing 23 and the lower gear housing 25 rotates, and the lower shaft held by the bearings of the lower gear housing 25 and the holder 35 When the fourth gear 33 in the lower gear housing 25 installed on the shaft 34 rotates, the lower shaft 34 whose tip is shaped into a hexagon rotates.

A hexagonal portion at the tip of the lower shaft 34
16 fits into the hexagon socket 17 formed in the female hexagonal hole of the short wrench 39, and the short wrench 39 rotates. Short wrench
The tip of 39 is formed in a hexagonal shape similarly to the above, and the hexagonal portion 18 is fitted with the hexagonal socket 19 of the seal shaft 40 of the closing plug 36.

When the short wrench 39 rotates clockwise, the core support plate 12
The seal shaft 40 of the closing plug 36 seated on the is rotated counterclockwise. It is screwed into a seal holder 41 having a female screw on the outer periphery of the seal shaft 40 having the male screw.

Referring to FIG. 3, the structure of the closing plug 36 will be described. The closing plug 36 is made up of a seal shaft 40, a seal box 41, and a seal portion 42, and inserts the tip of the seal shaft 40 into a hole of the seal box 41 which is formed with a hole at the center with the bag part of the cap nut 48 down, A seal shaft 40 having a male screw is screwed into a seal box 41 having a female screw by right rotation.

First, a Teflon sheet 43 is inserted from below into the tip of the seal shaft 40 which is inserted into the hole of the seal box 41 and protrudes downward, and then a ring 44 is inserted.
An O-ring 45 is fitted inside 44 and then a cylindrical seal packing 46 is placed. Next, a Teflon seal 47 is inserted, and finally a tapered cap nut 48 is tightened to fix the packing.

The seal box 41 has two pins on the outer peripheral surface.
4 and is held in the dovetail groove 20 of the holder 35 until it is inserted into the in-core guide tube 2 as shown in FIG. By lowering the sealing device, the pin moves relatively above the dovetail groove 20.

A television camera (not shown) confirms that the pin 49 has relatively moved above the dovetail groove 20, and when the upper shaft 28 is turned to the left, the short wrench 39 also starts to turn to the left. The seal shaft 40 into which 39 is inserted also rotates. Further, the seal box 41 fitted with the seal shaft 40 with the screw rotates about the seal shaft 40 by the frictional force of the screw.

By lowering the in-core guide tube sealing device 21, the pin 49 which has relatively moved above the dovetail groove 20 moves the dovetail groove 20 of the holder 35 to the left with respect to the seal box 41 which has started to rotate. When it has moved about 45 degrees and reached the dovetail groove 20 opened downward, it contacts the edge of the dovetail groove 20 and stops.

When the pin 49 stops at the dovetail groove 20 of the holder 35, the seal box fitted with the seal shaft 40 by a screw.
The friction force of the screw with 41 loses to the pin 49, and the seal box 41
Is stopped, only the seal shaft 40 rotates counterclockwise.

When only the seal shaft 40 rotates counterclockwise, when the seal shaft 40 rises inside the seal box 41 along the screw, the cap nut 48 at the tip of the seal shaft 40 also rises.
At this time, a compressive force acts on the rubber cylindrical seal packing 46 between the seal box 41 and the cap nut 48 to form an enlarged portion 46a which is deformed and locally expanded as shown in FIG. Adheres to the inner surface of the

The cylindrical seal packing 46 is pressed downward by a tapered cap nut by natural rubber, synthetic rubber, or another elastic body and is compressed and deformed. The outer peripheral surface of the cylindrical seal packing 46 is attached to the inner peripheral surface of the in-core guide tube 2. It is designed to seal the reactor water tightly.

Therefore, according to the present embodiment, the in-core guide tube sealing device 21 suspended from the refueling machine is easily guided to the in-core guide tube 2 by the guide 22 and easily closed to the insertion portion 37 of the in-core guide tube 2. By inserting the plug 36 and rotating the upper shaft 28 counterclockwise, the packing 46 is compressed and deformed so as to expand in the diametrical direction, and the degree of close contact with the inner peripheral surface of the in-core guide tube 2 is increased. improves.

On the other hand, after the cylindrical seal packing 46 is compressed and deformed, it
Since the pin 49 of the seal box 41 comes out of the downwardly opened dovetail groove 35, the closing plug 36 is removed from the holder 35 while removing the in-core guide tube sealing device 21 from the holder 35 while remaining on the core support plate 12. can do.

Next, the removal will be described. The in-core guide tube sealing device 21 suspended by the insulated wire 26 guides the holder 35 to the closing plug 36 by the guide 22. holder
When the pin 49 enters the downwardly opened dovetail groove 35, the upper shaft 28 is rotated clockwise. Each gear is upper shaft
When the seal shaft 40 rotates clockwise, the seal shaft 40 moves down the seal box 41 along the screw, reaches the bottom surface of the seal box 41, and the packing 46
The compression force is lost and the original shape is restored.

Even if the seal shaft 40 reaches the bottom surface of the seal box 41, when the seal shaft 40 further rotates clockwise, the seal shaft 40
Rotates rightward with the seal box 41. At this time pin 49
Moves the dovetail groove 20 of the holder 35 to the right, and finally contacts the edge of the dovetail groove 20 which is not opened downward and stops. Here, by pulling up the in-core guide tube sealing device 21 with the fuel wire, all the in-core guide tube seal device components can be collected.

Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 5 is a partially cutaway longitudinal sectional view of a closing cap 51 of an in-core guide tube sealing device 50 according to a second embodiment of the present invention. The present embodiment is an example in which a closing cap 51 is attached to the in-core guide tube 2 instead of the closing plug 36 of the in-core guide tube sealing device 21 shown in FIG.
Core support plate with the expansion of the strengthening work in the reactor in recent years
This is a sealing device for closing the in-core guide tube with the 12 and upper lattice plate 8 removed.

That is, in the closing cap 51, the closing plug 36 of the in-core guide tube sealing device 21 in the first embodiment makes the rubber cylindrical seal packing 46 adhere to the inner surface of the in-core guide tube 2 to seal the reactor water. On the other hand, the closing cap 51 is to seal the reactor water by bringing the cylindrical packing 53 into close contact with the outer surface of the in-core guide tube 2,
52, and a cap 58 screwed into the seal box 52.

The seal box 52 has a cylindrical shape whose upper, middle and lower parts are reduced in diameter.
The female screw is cut in the same manner as the closing plug 36. The diameter of the middle part is reduced by one step.
Fit 53. In addition, an incore guide tube 2 is provided at the lower end.
A trumpet-shaped guide 63 is provided to make it easy to enter.

The upper portion is provided with a pin 54 for moving through a dovetail groove 64 provided in the holder 59 at the time of removal, and is used like a closing plug. External wrench on top of holder 59
61 is connected. The inner wrench 60 is inserted into the outer wrench 61.

The first Teflon sheet is placed in the seal box 52.
55, the cylindrical seal outer packing 53 is fitted on the lower surface thereof, and then the second Teflon sheet 55 is placed on the lower surface of the cylindrical seal packing 53. Then, a cap 58 having a male screw having a hexagon socket 56 at an upper portion and an O-ring 57 at a lower portion is screwed into the seal box 52 and assembled.

In the same manner as in the first embodiment, the pin 54 of the seal box 52 is inserted into the dovetail groove 64 of the holder 59 at the lower end of the in-core guide tube sealing device 50, and the pin 54 is turned clockwise by 90 degrees. By fitting it into the dovetail groove 64 that is not open,
Do not drop the closing cap 51 during transfer.

As described at the beginning of the second embodiment, the core support plate 12 and the upper grid plate 8
There is no need to offset the in-core guide tube sealing device 50 on the way, so a linear wrench may be used.

The in-core guide tube sealing device 50 suspended in the furnace by the combustion wire 26 inserts the in-core guide tube 2 into the trumpet-shaped guide 63 at the tip of the seal box 52. The upper end of the in-core guide tube 2 passes through the packings 55, 53, 55 in the seal box 52, and is inserted into the locking portion 65 in the cap 58 to be seated.

When the incore guide tube 2 is seated on the cap 58, the inner wrench 60 is fixed on the refueling machine, and when the outer wrench 61 is rotated to the left, the cap 58 descends along the screw. Compressive force is applied to the seal seal 53,
The cylindrical seal packing 53 is compressed and deformed, and the in-core guide tube 2 is deformed.
To seal the reactor water.

When the tightening is completed, the pin 54 is aligned with the dovetail groove 64 which is opened downward to the holder 59, and the inner wrench 60 and the outer wrench 61 are pulled up with the insulated wire to close the cap.
Others can be recovered by leaving 51 in the in-core guide tube 2. The space 62 in the cap 58 is designed so as not to interfere with the lower surface of the cap 58 when the inspection device is raised to the uppermost part of the in-core guide tube 2.

When removing the inner wrench 60, the inner wrench 60 and the outer wrench 61 are suspended by the insulated wire 26, and the pins 54 are aligned with the dovetail grooves 64 which are opened downwardly of the holder 59.
When the outer wrench 61 is rotated right, the compressive force of the cylindrical seal packing 53 is released, and the original shape is restored. Turn outer wrench 61,
Align the pin 54 with the dovetail groove 64 that is not open downward and hold it with the holder 59,
Raise 0 and 61 together.

As described above, according to the second embodiment, the closing cap 51 can be directly attached to the in-core guide tube 2 even when the upper lattice plate does not exist. Further, when the incore guide tube 2 is detached, a closure is provided which is effective for reinforcement of structures in a nuclear reactor, for example, it can be attached to the incore housing only by lengthening a wrench. be able to.

[0062]

According to the present invention, the following effects can be obtained. (1) The insertion part of the in-core guide tube seal device inserted into the in-core guide tube can collect other in-core guide tube seal devices while leaving only the closing plug, which interferes with the use of other in-core inspection devices. As a result, it becomes easier to shorten the period of the periodic inspection, and when the operating rate of the nuclear power plant is improved, the energy generated by the oil can be reduced by the amount of the generated power, and the global environmental destruction can be prevented.

(2) By turning the closing plug of the insertion portion of the in-core guide tube sealing device from above the refueling machine with a wrench, not only the tightening torque can be controlled but also the degree of compressive deformation can be controlled, and the reliability of the seal can be improved. improves.

(3) By fixing the seal packing to the tip of the closing plug with a tapered cap nut, the insertability into the in-core guide tube insertion portion is improved, and the work of the in-core guide tube having 20 or more locations can be shortened.

(4) Since the seat is provided on the core support plate when the tip of the closing plug is inserted into the in-core guide tube insertion portion, the insertion portion can be extended by extending the seal shaft. The insertion amount inserted into the tube can be adjusted appropriately. In addition, since the elastic body can be installed at a position removed from the high-dose area, there is no need to replace the elastic seal packing even when the periodic inspection period is long.
It is possible to reduce radiation exposure of workers and shorten the period of periodic inspection.

(5) The in-core guide tube sealing device has an upper lattice plate guide attached to its wrench and is suspended from the reactor, so that the in-core guide tube seal device is easily and reliably inserted into a predetermined in-core guide tube. On the other hand, it can be easily removed, which reduces radiation exposure of workers and shortens the period of periodic inspection.

(6) A short wrench is provided at the lower end of the lower shaft, and a seal shaft is provided at the lower end of the short wrench, so that the in-core guide tube provided on the core support plate immediately below the intersection of the upper lattice plate. In addition, the seal packing can be compressed without interference with the upper lattice plate, the tightening torque can be controlled, the degree of compressive deformation can be controlled, and the reliability of the seal is improved.

(7) By providing a cylindrical seal packing which can be sealed in close contact with the inner surface of the in-core guide tube, even if the upper lattice plate or the core support plate does not exist due to replacement work, the cap or the seal is provided by a short wrench. By compressing and deforming the seal packing by rotating the box,
The seal packing can be brought into close contact with the inner surface of the in-core guide tube. In addition, it does not interfere with the use of other in-core inspection equipment, shortens the period of periodic inspections easily, and improves the operation rate of nuclear power plants. Can be prevented.

(8) By changing the lengths of the inner wrench and the outer wrench, the inner wrench can be used as a closing tool for the incore housing below the incore guide tube, so that the range of interference with the use of other in-furnace inspection devices is increased. In addition, the period of the periodic inspection can be shortened.

[Brief description of the drawings]

FIG. 1 shows a first embodiment of an in-core guide tube sealing device according to the present invention.
FIG. 3 is a longitudinal sectional view showing the embodiment of FIG.

FIG. 2 is a top view as seen from the direction of arrows AA in FIG. 1;

3A is a top view showing a state where a seal box is inserted into a seal shaft in FIG. 1, and FIG. 3B is a longitudinal sectional view showing a part of the side surface in FIG.

FIG. 4 is a side view partially showing a use example of the closing plug in FIG. 1 in a cross section.

FIG. 5 shows a second embodiment of the in-core guide tube sealing device according to the present invention.
FIG. 2 is a vertical cross-sectional view partially showing the embodiment of the present invention.

FIG. 6 is a longitudinal sectional view showing a state in which a neutron measurement tube for explaining a conventional example is attached to an in-core guide tube of a reactor core with a part cut away.

[Description of Signs] 1 ... Neutron measurement tube, 2 ... In-core guide tube, 3 ... In-core housing, 4 ... Lower mirror part of reactor pressure vessel, 5 ... Lead wire, 6 ... Spring, 7 ... Spindle, 8 ... Upper lattice Board, 8a
... intersection of upper lattice plate, 9 ... recess for support, 10,11 ... ring, 12 ... core support plate, 13 ... in-core flange, 14 ... mounting bolt, 15 ... tightening nut, 16, 18 ... hexagonal part, 17 , 19…
Hexagon socket, 20 ... dovetail groove, 21: incore guide tube sealing device (first embodiment), 22 ... guide, 23 ... upper gear housing, 24 ... intermediate pipe, 25 ... lower gear housing,
26 ... Combustion wire, 27 ... Hanging ear, 28 ... Upper shaft, 29 ...
1st gear, 30 ... 2nd gear, 31 ... intermediate shaft, 32 ...
Third gear, 33 ... fourth gear, 34 ... lower shaft, 35 ...
Holder, 36 ... closing plug, 37 ... insertion part, 38 ... bearing, 39 ... short wrench, 40 ... seal shaft, 41 ... seal box, 42 ... seal part, 43 ... Teflon sheet, 44 ... ring, 45 ... O-ring, 46 ... cylindrical seal packing, 47 ... Teflon sheet, 48 ... cap nut, 49 ... pin, 50 ... in-core guide tube sealing device (second embodiment), 51 ... closing cap, 52 ... seal box, 53 ... cylinder Seal packing,
54… Pin, 55… Teflon sheet, 56… Hex socket, 57
... O-ring, 58 ... Cap, 59 ... Holder, 60 ... Internal wrench, 61 ... Outer wrench, 62 ... Cap space, 63 ... Guide,
64 ... Dove groove.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hidehiko Yasuda 2-4-4 Suehirocho, Tsurumi-ku, Yokohama-shi, Kanagawa Prefecture Inside the Toshiba Keihin Works (72) Inventor Yoshiaki Ono 2--4, Suehirocho, Tsurumi-ku, Yokohama-shi, Kanagawa Address F-term in Toshiba Keihin Works (reference) 2G075 AA03 BA18 CA08 CA49 DA01 FA19 FA20 FC14 GA15 GA37 GA38

Claims (5)

[Claims] 1. A core instrumentation guide tube is attached to a core support plate provided in a reactor pressure vessel, and is inserted into and detachable from the reactor core guide tube so that the reactor instrumentation guide tube is watertight. A sealing device for an in-core instrumentation pipe for sealing, comprising a closing plug for sealing the inside of the in-core instrumentation pipe in a watertight manner, the closing plug being screwed into the seal box and screwed into the in-furnace instrumentation guide. A seal shaft having a seal portion that is inserted into the pipe to seal watertightly, and when the seal portion is inserted into the in-furnace instrumentation guide tube, the diameter of the seal portion expands to make it watertight with the inner surface of the in-furnace instrumentation guide tube. A sealing device for an in-furnace instrumentation guide tube, comprising a cylindrical elastic seal packing in contact with a pipe. 2. The seal box has a pin protruding from an outer surface thereof. The seal box is supported by a holder having a dovetail groove into which the pin is inserted, and the seal shaft is connected to a short wrench from above by screwing. 2. The sealing device for an instrumentation guide tube in a furnace according to claim 1, wherein the device is connected to a lower shaft. 3. The lower shaft is connected via a gear to an intermediate shaft passing through an upper lattice plate provided in the reactor pressure vessel, and the intermediate shaft is connected via a gear to an upper shaft projecting from the operation floor. 3. The sealing device for an in-furnace instrumentation guide tube according to claim 2, wherein the sealing device is connected by connecting. 4. A cap having an upper end closed to cover an upper end portion of an in-core instrumentation guide tube, a seal box surrounding the outside of the cap and being screwed together, a lower inner side of the seal box and the in-furnace meter. And a cylindrical elastic seal packing provided between the upper outer surface of the mounting guide tube and the lower end surface of the cap so as to be pressed and supported. 5. The seal box is provided with a pin, a holder having a dovetail groove into which the pin is inserted is provided, an outer wrench is connected to the holder, and an inner wrench inserted into the outer wrench is provided above the cap. 5. The sealing device for an in-core instrumentation guide tube according to claim 4, wherein the sealing device is connected.