JP2003156587A - Recirculation outlet nozzle seal device of reactor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform maintenance and checking work of piping and components of coolant recirculation system without draining coolant in the reactor pressure vessel by inserting a plug in a recirculation outlet nozzle from inside and water- tightly sealing. SOLUTION: The device comprises a plug 22 inserted freely detachably in the recirculation outlet nozzle 4 of the reactor pressure vessel 1 from the inner open end and blocking the outlet nozzle, a flange arranged on the plug and attached to the outer periphery of the inner open end of the recirculation outlet nozzle, a freely extendable plug detaching device 36 installed on the flange, and detachably inserting the plug in the recirculation outlet nozzle by hooking the movable open end on the core shroud when extending, tube seals 25 and 26 which is freely expanding and contracting by flowing in and out of pressurizing fluid and sealing the gap between the plug outer surface and the inner surface of the recirculation outlet nozzle, and a press seal 33 touching the inner open end outer periphery of the recirculation outlet nozzle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a recirculation outlet nozzle sealing device for a reactor, in which a recirculation outlet nozzle of a reactor pressure vessel to which a recirculation pump is connected via a pipe is watertightly plugged from the inside. Regarding

[0002]

2. Description of the Related Art Generally, as shown in FIG. 6, a boiling water reactor has a bottomed cylindrical reactor pressure vessel 1 for containing light water, and its hemispherical head 1a is openable and closable. It will be opened during the regular inspection of. The reactor pressure vessel 1 comprises a steam outlet pipe 2, a feed water inlet pipe 3 and a recirculation outlet nozzle 4. A recirculation loop pipe 5 is connected to the recirculation outlet nozzle 4, a recirculation pump 6 is interposed in the recirculation loop pipe 5, and the first and first recirculation pump pipes are provided on the upstream side and the downstream side. Two on-off valves 7 and 8 are provided respectively.

An outlet end 5a of the recirculation loop pipe 5 is connected to an outer end of a recirculation inlet nozzle 9 of the reactor pressure vessel 1, and an inner end of the recirculation inlet nozzle 9 is connected to the reactor pressure vessel 1. It is connected to the jet pump 10 inside. A plurality of jet pumps 10 are arranged in the annular gap between the shroud 11 and the inner peripheral surface of the reactor pressure vessel 1 at a predetermined pitch in the circumferential direction. By driving these jet pumps 11, the reactor water is circulated in a ring-shaped pattern around the shroud 11.

The shroud 11 has a core portion 13 in which a plurality of nuclear fuels 12 are loaded. A steam generator 14 and a steam dryer 15 are arranged above the shroud 11.

By the way, in the boiling water reactor constructed as described above, the reactor water in the reactor pressure vessel 1 is not drained and the recirculation loop is not drained when the nuclear fuel 12 is not in operation for loading or maintenance. It is necessary to separate the pipe 5 and drain water.

Conventionally, during maintenance and repair work of the suction pipe of the recirculation loop pipe 5, the reactor water in the reactor pressure vessel 1 reaches a side surface of the reactor pressure vessel 1 to a water level lower than the height of the recirculation outlet nozzle 4. It was necessary to drain the.

However, since the recirculation outlet nozzle 4 is generally installed at a position lower than the core portion 13 in which the nuclear fuel 12 is loaded, the coolant can be discharged unless all the nuclear fuel 12 in the core portion 13 is removed. Can not. However, such an operation requires a lot of cost and time, and requires handling and storage of radioactive materials, resulting in cost increase.

The recirculation loop pipe 5 can be separated and drained by shutting off the first and second on-off valves 7 and 8 of the recirculation loop pipe 5. In addition to requiring general maintenance, it is not possible to disconnect or drain water while these on-off valves 7 and 8 are in use. In addition, it has been found that the on-off valves 7 and 8 are prone to liquid leakage if they are not maintained.

Therefore, a method is conceivable in which maintenance inspection work is carried out by inserting a nozzle plug into the recirculation outlet nozzle 4 and plugging the nozzle plug to prevent the coolant in the reactor pressure vessel 1 from being extracted.

[0010]

However, when such a nozzle plug is used, the recirculation outlet nozzle 4 is a horizontal nozzle that horizontally projects near the bottom of the reactor pressure vessel 1. However, the inside of the reactor pressure vessel 1 has a small work space and is a remote operation in water, so that workability is difficult and positioning with high accuracy is required. Further, since the recirculation outlet nozzle 4 is located at a deep water location in the reactor pressure vessel 1, the water pressure (head pressure) is high in the sealing material related to the nozzle plug sealing mechanism. Therefore, it is considered that the water pressure causes the seal material to be crushed or twisted.

Therefore, conventionally, when the maintenance and inspection of the coolant recirculation system such as the recirculation loop pipe 5 and the equipment are carried out as described above, all the coolant in the reactor pressure vessel 1 is extracted. After that, maintenance and inspection work must be carried out, and improvement of shortening the regular inspection process is requested.

The present invention has been made in view of the above circumstances, and an object thereof is to insert a plug from the inside into a recirculation outlet nozzle and seal it watertightly.
It is an object of the present invention to provide a reactor recirculation outlet nozzle seal device that enables maintenance and inspection work of the coolant recirculation system piping and equipment without extracting the coolant in the reactor pressure vessel. .

[0013]

The invention according to claim 1 is
In the recirculation outlet nozzle of the reactor pressure vessel containing the core shroud, insertable and removable from its inner open end,
A plug for closing the outlet nozzle, a flange disposed on the plug and abutting on the outer peripheral portion of the inner opening end of the outlet nozzle when the plug is inserted into the recirculation outlet nozzle; An expandable and retractable plug inserting / removing device that is attached to the flange and that allows the movable free end to be locked to the core shroud during expansion and inserts the plug into the recirculation outlet nozzle so that the plug can be inserted and removed. A sealing member that is provided and is expandable and contractible by the inflow and outflow of a pressurized fluid, and seals the gap between the outer peripheral surface of the plug and the inner peripheral surface of the recirculation outlet nozzle when expanding, and the inner opening of the recirculation outlet nozzle. A recirculation outlet nozzle sealing device for a nuclear reactor, comprising: a pressure seal protruding from an abutting surface of the flange that abuts an outer peripheral edge portion.

According to a second aspect of the present invention, in the pressure seal, the seal tip portion is formed in a mountain-shaped projection shape, the seal tip portion is made of a soft rubber material, and the seal base portion is made of a hard rubber material. The recirculation outlet nozzle sealing device for a nuclear reactor according to claim 1, wherein the recirculation outlet nozzle sealing device has a two-layer structure.

According to a third aspect of the present invention, the seal member has a tube for expanding and contracting a pressurized fluid, and the inside of the tube is engaged with an engaging portion of the tube. The recirculation outlet of a nuclear reactor according to claim 1 or 2, characterized in that the metal fitting having a groove is housed therein and is configured to slide along the engagement groove when the tube seal is expanded under pressure. It is a nozzle seal device.

The invention according to claim 4 is characterized in that the plug is integrally fixed to the flange by a plurality of fastening members arranged in a zigzag manner in the circumferential direction. The recirculation outlet nozzle sealing device for a nuclear reactor according to any one of 3 above.

The invention according to claim 5 is the recirculation outlet nozzle sealing device for a nuclear reactor according to any one of claims 1 to 4, wherein the plug has a hollow structure.

The invention according to claim 6 is the recirculation outlet nozzle sealing device for a nuclear reactor according to claim 5, wherein the plug has a hollow corner portion formed into a curved surface.

According to a seventh aspect of the present invention, the plug insertion / removal device includes an expandable / retractable pantograph mechanism and a hydraulically actuated piston for driving the pantograph mechanism to expand / contract. Item 1 is a recirculation outlet nozzle sealing device for a nuclear reactor.

The invention according to claim 8 is the recirculation outlet nozzle seal device for a nuclear reactor according to claim 7, characterized in that the working piston is configured to be driven by remote control.

According to a ninth aspect of the present invention, when the plug is inserted into the recirculation outlet nozzle, the reactor water between the seal member and the pressure seal is drained while the air is supplied to the nozzle. , Having a pipe connected to this nozzle,
This pipe extends to the outside of the nuclear reactor, and by supplying compressed air from this pipe, the reactor water between the seal member and the pressure seal is removed to form an air space, and this air space has an air seal function. The recirculation outlet nozzle sealing device for a nuclear reactor according to any one of claims 1 to 8, which is configured as described above.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to FIG.
~ It demonstrates based on FIG. In these figures, the same or corresponding parts are designated by the same reference numerals.

FIG. 1 shows a reactor pressure vessel 1 in which a recirculation outlet nozzle sealing device 21 according to an embodiment of the present invention is shown in FIG.
FIG. 2 is a side view showing a state in which it is expanded and contracted, FIG. 2 is a plan view of the expanded state, and FIG.
It is a III line arrow line view.

As shown in these figures, the recirculation outlet nozzle sealing device 21 seals the recirculation outlet nozzle 4 of the reactor pressure vessel 1 shown in FIG. 6 from the inside in a watertight manner. And a cylindrical plug 22 that can be inserted and removed from the inside of the reactor pressure vessel 1.

This plug 22 has a plurality of tightening bolts 24 shown in FIG. 2 at one axial end of which a disk-shaped outward flange 23 having a diameter larger than that of the inner opening end 4a of the recirculation outlet nozzle 4 is shown.
Are attached concentrically. The plurality of tightening bolts 24 are screwed from the outer surface side of the outward flange 23 toward the one end side of the plug 22 to fix the outward flange 23 to the plug 22. These tightening bolts 24 are arranged inside and outside twice at a predetermined pitch in the circumferential direction at the inner peripheral portion of the outer surface of the outward flange 23, and the arrangement of these inside and outside double tightening bolts 24 is alternated in the circumferential direction. They are arranged in a staggered pattern.

The plug 22 is a bottomed cylindrical plug body 22.
A lid 22c is fixed to the opening tip 22b of the a by fastening bolts or the like, and the corner of the hollow portion 22d is rounded.
It is formed by e.

In the plug 22, the tube seals 25 and 26 of the first and second stages, which are an example of a seal member, are arranged on the outer peripheral surface of the plug body 22a side by side with a required interval in the axial direction.

As shown in FIG. 4, the first and second tube seals 25 and 26 are provided with peripheral grooves 27 and 28, each having a rectangular cross section and a large outer end opening, on the outer peripheral surface of the plug body 22a. Formed in these peripheral grooves 27, 28 are annular sealing tubes 25a, 26a having elasticity, the outer peripheral surface of which is substantially flush with the outer ends of the openings of the peripheral grooves 27, 28, or slightly outwardly protruding. And fixed in each tube 25a, 25
On the outer peripheral surface of b, a plurality of protrusions 25c, 26c,
... is protruding.

Further, the tubes 25a and 26a are formed with reduced diameter portions 25b and 26b, respectively, which are reduced in diameter in the middle portion in the radial direction. Engaging metal fittings 29, 30 to be engaged
Is inserted and one end of each of the engaging fittings 29, 30 is fixed to the bottom of each circumferential groove 27, 28.

Further, in each tube seal 25, 26, a separate system supply / discharge pipe 31, 32 for supplying / exhausting compressed air and compressed liquid (water), which are pressurized fluids, to / from each tube 25a, 26a. Are connected to each other, and each tube 25a, 26a expands when these pressurized fluids are supplied,
It is designed to shrink when ejected. Supply and discharge piping 31,3
One end of 2 extends to the outside of the reactor pressure vessel 1 and is connected to a compressed fluid supply / exhaust device (not shown) for supplying or discharging compressed liquid of compressed air.

On the other hand, the outward flange 23 is in contact with the outer peripheral portion of the inner opening end 4a of the recirculation outlet nozzle 4, and the contact surface 23.
An annular pressure seal 33 is concentrically arranged on the outer peripheral surface of a.

As shown in FIG. 5, the pressing seal 33 is made of hard rubber or the like and has an elastic ring-shaped base 33a.
On the tip (outer end) of the ring-shaped seal portion 3 made of soft rubber or the like which is softer than the base 33a and has elasticity.
3b are laminated and fixed. The tip portion (outer end portion) of the seal portion 33b is integrally formed with a protrusion 33c having a mountain-shaped radial cross section, and the mountain-shaped protrusion 33c is elastically attached to the outer peripheral portion of the inner opening end of the recirculation outlet nozzle 4. Abutting against each other and sealing in a watertight manner.

On the other hand, the base 33a of the pressure seal 33 is
Outward flanges that project outward are integrally formed on both sides in the radial direction of the base end portion to form step portions 33a1 respectively, and inner and outer annular rings that engage with these step portions 33a1 respectively. The pressing plates 34a and 34b are fixed to the outward flange 23 with tightening bolts or the like, and thereby the pressing seal 33 is fixed to the outward flange 23.

As shown in FIGS. 1 and 2, a patch plate 35 smaller than the plug 22 is concentrically fixed to the central portion of the outer surface of the outward flange 23 opposite to the mounting surface of the plug 22. A retractable plug insertion / removal device 36 is attached to the contact plate 35.

The plug inserting / removing device 36 is a pair of front and rear (in FIG. 2, left and right in FIG. 2) expandable and retractable pantograph mechanisms 37 and 38, for example, rhombus, and these pantograph mechanisms 37 and 3.
And a hydraulic cylinder 39 that drives 8 to expand and contract.

As shown in FIG. 2, the pair of front and rear pantograph mechanisms 37 and 38 are arranged symmetrically with respect to the central axis O of the plug body 22a as a symmetrical axis, and in FIG. 1, the front and back directions of the paper surface (the left and right directions in FIG. 2). They are rotatably connected by a pair of upper and lower hinge pins 40 and 41 extending in the direction.

That is, the front end portion (the left end portion in FIG. 2) of the upper hinge pin 40 is integrally connected to the hinge pin of the upper movable node of the rhombus link in FIG. 1 of the front pantograph mechanism 37, while the front end portion of the lower hinge pin 41 ( (The left end in Figure 2)
Is integrally connected to the hinge pin of the lower movable node of the rhombus link in FIG. 1 of the front pantograph mechanism 37.

Further, the rear end portion (the right end portion in FIG. 2) of the hinge pin 40 is integrally connected to the hinge pin of the upper movable node of the rhombus link of the rear pantograph mechanism 38, while the rear end portion of the lower hinge pin 41 is moved rearward. The diamond link of the pantograph mechanism 38 is integrally connected to the hinge pin of the lower movable part.

Then, these pantograph mechanisms 37, 3
1, a pair of upper and lower end portions 37 of each plug 22 of FIG.
2, a, 37b, 38a, 38b are rotatably pivoted to the left and right end portions of the contact plate 35 in FIG. 2, while the pair of upper and lower end portions 37 of the pantograph mechanisms 37, 38 on the shroud 11 side are provided.
A pressing plate 42 is rotatably and pivotally attached to the c, 37d, 38c, and 38d, and the pressing plate 42 is attached to each pantograph mechanism 37,
It is configured as a movable free end of the movable and retractable 38.

Further, as shown in FIG. 2, the ends of the pair of pantograph mechanisms 37 and 38 on the plug 22 side are provided with a gap slightly larger than the plate thickness of each link inside, for example, two links are rotated. Reinforcing links 43 and 44 of two-joint links which are movably connected are arranged in parallel.

As shown in FIGS. 1 and 2, a pair of upper and lower hinge pins 40, 41 are axially connected to each other by a hydraulic cylinder 39.

That is, as shown in FIG. 1, the hydraulic cylinder 39 includes a cylinder 39a and a piston plunger 39 connected to a piston housed therein so as to be reciprocally movable.
1 b of the cylinder 39a is pivotally attached to the axially intermediate portion of the upper hinge pin 40 while the outer end portion (lower end portion in FIG. 1) of the piston plunger 39b is attached to the lower hinge pin. It is pivotally attached to the axially intermediate portion of 41.

The water pressure cylinder 39 supplies drive water of a required pressure into the cylinder 39, while driving water supply / discharge pipes (not shown) for draining the drive water, and controlling the supply and discharge of the drive water. A remote control device (not shown) that expands and contracts the pantograph mechanisms 37 and 38 by expanding and contracting the cylinder 39 in the axial direction is provided.

Then, as shown in FIG. 2, in the state where the recirculation outlet nozzle sealing device 21 seals the recirculation outlet nozzle 4, the tube seal 26 and the pressure seal 33 in the subsequent stage and the rounded angle of the recirculation outlet nozzle 4 are shown. A drainage / air supply nozzle 45 that supplies compressed air while draining the reactor water in a gap g formed between the drainage and air supply portion, and a drainage / air supply pipe (not shown) connected to the drainage / air supply nozzle 45. A drainage / air supply device (not shown) that is connected to one end of a drainage / air supply pipe extending to the outside of the reactor pressure vessel 1 to discharge air and supply air of a predetermined pressure while being drained.

Next, the method of use and the operation of the recirculation outlet nozzle sealing device 21 thus constructed will be described.

First, the entire recirculation outlet nozzle sealing device 21 is suspended by a wire rope or the like with the pantograph mechanisms 37, 38 contracted, and further suspended in the reactor pressure vessel 1 to adjust the length of the wire rope. By adjusting the position, the position and the posture of the nozzle plug 22 are gradually adjusted and positioned to the position of the recirculation outlet nozzle 4 to be sealed, and first the tip of the plug body 22a is placed inside the recirculation outlet nozzle 4. insert.

Next, drive water is supplied to the hydraulic cylinder 39,
Extend this hydraulic cylinder. Then, as shown in FIG. 1, the pantograph mechanisms 37 and 38 are extended, the holding plate 42 at the movable free end is pressed against the outer peripheral surface of the shroud 11 and locked, and the reaction thereof causes the plug body 22a to recirculate and exit. It moves into the nozzle 4 and is inserted. At this time, the nozzle plug body 22a is gradually anastomosed to the recirculation outlet nozzle 4 while being kept horizontal. At this time, at the same time, the chevron-shaped protrusions 33c of the pressing seal 33 of the outward flange 23 are elastically pressed against the inner wall surface of the reactor pressure vessel 1, so that the first seal can be activated first.

Next, a pressurized fluid such as compressed air is supplied from the outside of the reactor pressure vessel 1 into the tube seals 25a, 26a of the two-stage tube seals 25, 26 of the plug 22 through the supply / discharge pipes 31, 32. The tube seals 25 and 26 are inflated by sending them, and these tube seals 2
The plurality of convex portions 25c, 26c on the outer peripheral surfaces of the plugs 5, 26 elastically contact the inner peripheral surface of the recirculation outlet nozzle 4,
The gap between the outer peripheral surface of 2a and the inner peripheral surface of the recirculation outlet nozzle 4 is sealed.

In this way, the recirculation outlet nozzle 4 near the bottom of the reactor pressure vessel 1 can be reliably sealed in a watertight manner by the recirculation outlet nozzle sealing device 21 in a short time. Therefore, maintenance and inspection work of the piping and equipment of the coolant recirculation system can be performed without extracting the coolant (reactor water) from the reactor pressure vessel 1. As a result, it is possible to significantly reduce the work time.

Further, since the pressurized fluids to be supplied to the two tube seals 25 and 26 are water and air having a predetermined pressure and are supplied and discharged by separate systems, one system should fail. If the above occurs, the other system can be operated.

Further, the tube seals 25, 26 are fitted with metal fittings 29, 30 which engage with the tubes 25a, 26a, respectively.
Slide along the groove that engages during pressurization and expansion of the metal fitting 2
It is possible to prevent the tube seals 25, 26 from coming off the 9, 30.

Further, since the hollow portion 22d is formed in the plug body 22a to form a hollow structure, the weight can be reduced and the open end 22b of the hollow portion 22d can be achieved.
Since the lid is closed by the lid 22c, it is possible to prevent the intrusion of the reactor water into the hollow portion 22a and improve the strength of the plug body 22a.

Further, the hollow portion 22d of the plug body 22a
Since the corner portion is formed into the radius 22e, it is possible to prevent or reduce the concentration of stress on the corner portion.

The recirculation outlet nozzle sealing device 21
Each pantograph mechanism 37, 3 is controlled by remotely controlling the expansion and contraction of the hydraulic cylinder 39 of the reactor from outside the reactor pressure vessel 1.
Since the plug 22 can be inserted into the recirculation outlet nozzle 4 by expanding and contracting 8, the radiation exposure dose of the operator of the recirculation outlet nozzle sealing device 21 can be reduced, and the work safety can be improved. You can

Further, with the recirculation outlet nozzle sealing device 21 thus constructed arranged at a predetermined position in the recirculation outlet nozzle 4, the tube seals 25 and 26 and the pressure seal 33 are controlled by the drainage / air supply nozzle 45. This space can be configured as an air space of a predetermined pressure by draining the reactor water between the space and the outside of the reactor pressure vessel 1 and then supplying air of a predetermined pressure, so that the air space is air-sealed. be able to.

[0056]

As described above, according to the present invention, the recirculation outlet nozzle, which is a nozzle that projects horizontally (horizontally) at a position near the bottom of the reactor pressure vessel, is provided with a working space inside thereof. In a narrow space, the recirculation outlet nozzle sealing device can be used for remote work to perform watertight sealing in a short time and reliably, which enables regular inspection and maintenance of recirculation piping and equipment without draining water from the reactor pressure vessel. Can be done.

[Brief description of drawings]

FIG. 1 is a side view of a recirculation outlet nozzle sealing device according to an embodiment of the present invention.

FIG. 2 is a plan view of FIG.

3 is a view taken along the line III-III in FIG.

FIG. 4 is an enlarged view of the tube seal shown in FIGS. 1 and 2.

5 is an enlarged view of the pressure seal shown in FIGS. 1 and 2. FIG.

FIG. 6 is a vertical sectional view of a general boiling water reactor pressure vessel.

[Explanation of symbols]

1 Reactor pressure vessel 1a head (head) 2 steam dryer 3 steam generator 4 Recirculation outlet nozzle 6 Recirculation pump 21 Recirculation outlet nozzle sealing device 22 plug 22a Plug body 22d Plug hollow part 22e Ear of hollow part of plug 23 Outward flange 24 Tightening bolt 25 1st tube seal 26 Second tube seal 29,30 Engagement fitting 31, 32 Supply and discharge piping 33 Press seal 36 Plug insertion / removal device 37,38 a pair of pantograph mechanism 39 hydraulic cylinder 40,41 a pair of hinge pins 42 Presser plate

Continued front page    (72) Inventor Nei Kanazawa             8th Shinsugita Town, Isogo Ward, Yokohama City, Kanagawa Prefecture             Ceremony company Toshiba Yokohama office (72) Inventor Tsuyoshi Maehara             2-4 Suehiro-cho, Tsurumi-ku, Yokohama-shi, Kanagawa               Toshiba Keihin Office (72) Inventor Makoto Sato             2-4 Suehiro-cho, Tsurumi-ku, Yokohama-shi, Kanagawa               Toshiba Keihin Office (72) Inventor Soichiro Ueda             2-3 Mitsugaoka, Nishi-ku, Kobe-shi, Hyogo 5-5               Rokuryo Rubber Co., Ltd. (72) Inventor Masaki Hara             2-3 Mitsugaoka, Nishi-ku, Kobe-shi, Hyogo 5-5               Rokuryo Rubber Co., Ltd.

Claims (9)

[Claims] 1. A plug inserted into a recirculation outlet nozzle of a reactor pressure vessel accommodating a core shroud so as to be removably inserted from an inner open end thereof and closing the outlet nozzle, and a plug disposed on the plug. A flange that abuts the outer peripheral portion of the inner opening end of the outlet nozzle when the plug is inserted into the recirculation outlet nozzle, and a flange that is attached to the flange and that has a movable free end that engages with the core shroud when extended. A retractable plug insertion / removal device for stopping and inserting the plug into the recirculation outlet nozzle, and an expandable / contractible device that is arranged on the outer peripheral surface of the plug and that is inflated and contracted by the inflow / outflow of a pressurized fluid. A seal member that seals a gap between the outer peripheral surface of the plug and the inner peripheral surface of the recirculation outlet nozzle at the time of expansion, and abutment of the flange that abuts the inner peripheral edge of the inner end of the recirculation outlet nozzle. Recirculation outlet nozzle seal arrangement of the reactor, characterized by comprising a pressing seal which projects, to. 2. The pressure seal has a two-layer structure in which the seal tip portion is formed in a mountain-shaped projection shape, the seal tip portion is made of a soft rubber material, and the seal base portion is made of a hard rubber material. The recirculation outlet nozzle seal device for a nuclear reactor according to claim 1, wherein the recirculation outlet nozzle seal device is formed. 3. The seal member has a tube into and out of which a pressurized fluid enters and leaves, and inside the tube,
A metal fitting having an engagement groove that engages with the engagement portion of the tube is accommodated, and is configured to slide along the engagement groove when the tube seal is pressurized and expanded. Item 3. A recirculation outlet nozzle sealing device for a nuclear reactor according to Item 1 or 2. 4. The plug is integrally fixed to the flange by a plurality of fastening members arranged in a zigzag pattern in the circumferential direction. Recycle outlet nozzle sealing device for a nuclear reactor according to 1. 5. The recirculation outlet nozzle sealing device for a nuclear reactor according to claim 1, wherein the plug has a hollow structure. 6. The recirculation outlet nozzle sealing device for a nuclear reactor according to claim 5, wherein the plug has a hollow corner portion formed into a curved surface. 7. The plug insertion / removal device comprises a retractable pantograph mechanism, and a hydraulically actuated piston for driving the pantograph mechanism to extend and contract. Recirculation outlet nozzle sealing device. 8. The recirculation outlet nozzle seal device for a nuclear reactor according to claim 7, wherein the working piston is configured to be driven by remote control. 9. When the plug is inserted into the recirculation outlet nozzle, it drains the reactor water between the seal member and the pressure seal while supplying air, and a nozzle connected to this nozzle. This pipe extends outside the reactor, and compressed air is supplied from this pipe to remove reactor water between the seal and the pressure seal to form an air space. The recirculation outlet nozzle sealing device for a nuclear reactor according to any one of claims 1 to 8, which is configured to have an air sealing function.