JPH0868887A - Attaching detaching device and its aandling for internal pump - Google Patents

Abstract

PURPOSE: To provide attaching detaching device for internal pump and its han dling capable of shortening the maintenance and inspection works for the inter nal pump and improving the availability factor of the reactor by independently separating the detaching work for secondary seal mechanism from the detaching work for the pump impeller. CONSTITUTION: The attaching/detaching device 35 for an internal pump 23 has a motor casing 9 hung below the bottom plate of a reactor pressure vessel 10, a secondary seal mechanism 36 placed at the shoulder part 15 of the motor casing 9 and a secondary seal treatment tool 50 inserted from below the motor casing 9 and connected detachably with the secondary seal mechanism 36. The secondary seal treatment tool 50 is provided with a decoupling means 57, 70 for releasing the coupling between the secondary seal mechanism and the motor easing 9 and forms a cylindrical space capable of inserting a drive shaft 3 for the pump impeller 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal pump provided in an improved boiling water nuclear reactor, and more particularly to an internal pump attachment / detachment device and an internal pump for facilitating replacement work of a secondary seal. Regarding how to handle the pump.

[0002]

2. Description of the Related Art Improved boiling water reactor (hereinafter referred to as ABWR
Say. ), Multiple internal pumps are attached to the reactor pressure vessel, and this internal pump is designed to forcibly recycle the reactor water in the reactor.

The internal pump provided in the ABWR is constructed as shown in FIG. 10, and is composed of a motor section 1 and a pump section 2. The rotational driving force from the motor section 1 is passed through a drive shaft 3 to the pump section. 2 and pump section 2
The pump impeller 4 is driven to rotate.

The pump unit 2 has a diffuser 6 installed in an annular downcomer unit 5 and a pump impeller 4 housed in the diffuser 6, and the pump impeller 4 is installed on the top of the drive shaft 3 so as to rotate integrally therewith.

On the other hand, the motor unit 1 includes a stator 7 and a rotor 8.
And is housed in the motor casing 9.
The motor casing 9 has an upper part (neck) at the reactor pressure vessel 1
No. 0 is fixed to the nozzle 11 protruding from the lower mirror portion 10a by welding or the like, and is vertically installed. The pump portion 2 is provided on the top of the nozzle 11.
The diffuser 6 is mounted on the nozzle 11 by the stretch tube 13 and its tube nut 14.

The stretch tube 13 is inserted in the neck portion of the motor casing 9, and the lower end thereof is tightened and fixed by the stretch tube nut 14. The drive shaft 3 is inserted into the stretch tube 13 from above,
The lower portion of the drive shaft 3 is inserted into and fixed to the rotor 8 of the motor unit 1, so that the rotational driving force of the motor unit 1 is transmitted.

The stretch tube nut 14 is provided on the shoulder portion 15 of the motor casing 9, and a secondary seal mechanism 16 (hereinafter referred to as a secondary seal) is mounted below the stretch tube nut 14. Secondary seal 1
A secondary seal pressurizing pipe 17 is provided on the back side of 6,
Water pressure is applied to the back side of the secondary seal 16 via the pressurizing pipe 17, and the elastomer constituting the sealing means of the secondary seal 16 is pressed into contact with the drive shaft 3 for sealing.

Further, the primary seal is constituted by the metal contact between the collar portion of the drive shaft 3 and the upper surface 13a of the stretch tube 13. The primary seal seals the reactor water to prevent leakage of the reactor water. ing.

A cooling water circulation pipe 19 is attached to the upper and lower parts of the body portion 18 of the motor casing 9, and the cooling water circulation pipe 19 forcibly circulates the cooling water in the motor portion 1 to move the motor portion 1 to the motor portion 1. It is cooled to prevent its burnout.

The internal pump undergoes maintenance and inspection work at the time of periodic inspection of the ABWR and the like. In the conventional internal pump, normal maintenance work is performed as follows.

In the maintenance and inspection work of the internal pump, the motor unit 1 is first removed from the motor casing 9, but in order to prevent the leakage of the reactor water when the motor unit 1 is removed, the drive shaft 3 and the stretch tube 13 are connected to each other. Constitutes a primary seal between.

After that, pressurized water is supplied from the secondary seal pressurizing pipe 17 to pressurize the back side of the secondary seal 16 so that the elastomer is brought into close contact with the drive shaft 3 and the space between the motor casing 9 and the drive shaft 3 is brought into contact with the drive shaft 3. Seal and shut off the reactor water in the reactor pressure vessel 10.

After the secondary sealing, the lid (closing) flange 20 of the motor casing 9 is removed and the motor unit 1 is removed from below the casing.

After the motor unit 1 is removed from the motor casing 9, a closing flange 20 is attached to the motor casing 1 to seal the inside of the motor casing 9, and the motor casing 9 is filled with makeup water in this sealed state. After filling the motor casing 9 with makeup water, the secondary seal 1
Release 6.

The reactor pressure vessel 10 with the secondary seal released.
From above, the pump impeller 4 is pulled out together with the drive shaft 3 and removed. The work of removing the pump impeller 4 and the drive shaft 3 is performed by using a lifting machine on the refueling machine.

After removing the pump impeller 4 and the drive shaft 3 above the reactor pressure vessel 10, the diffuser 6
The opening is closed with the upper plug 21 shown in FIG. 11 to seal the water. In this sealed state, the makeup water in the motor casing 9 is discharged, and in this discharged state, the closing flange 20 of the motor casing 9 is removed.

After removing the closing flange 20, the secondary seal 16 is removed using the replacement rotary mount of the control rod drive mechanism, and the secondary seal 16 is maintained, inspected and repaired.

After removing the secondary seal 16 downward from the motor casing 9, a closing flange 20 is attached to the lower end of the motor casing 9 to refill the inside of the motor casing 9 with makeup water. The upper plug 21 is removed from above the reactor pressure vessel 10 with the makeup water being filled.

After the inspection, repair, and maintenance of the motor unit 1 and the secondary seal 16 of the removed internal pump, the motor unit 1, the pump impeller 4, the drive shaft 3 and the secondary seal 16 are reattached. The internal pump is installed in the reverse order of the pump removal.

In this way, maintenance of the internal pump
The inspection / maintenance work is divided into an upper part and a lower part of the reactor pressure vessel 10. The upper part of the reactor pressure vessel 10 is carried out by using a lifting machine on a refueling machine as described in JP-A-58-14092, and the lower part thereof is described in JP-A-62-96896. The control rod drive mechanism as described above is used for replacement.

[0021]

In the maintenance and inspection work of the internal pump, the pump impeller 4 and the drive shaft 3 are removed and attached, and the upper plug 21 is attached and detached by using the lifting machine of the fuel exchanger. Therefore, while the attachment / detachment work takes a long time, it cannot be used while the fuel assembly is being replaced by the fuel exchanger, and the work cannot be carried out. Similarly, during inspection work of the control rod drive mechanism, the rotary mount cannot be used, and the secondary seal 16 cannot be removed or attached.

On the other hand, the secondary seal 16 applies water pressure from the back side of the elastomer constituting the seal portion to bring the elastomer into pressure contact with the surface of the drive shaft 3 to seal it, and the reactor water in the reactor pressure vessel 10 is sealed. Since it is intended to block water leakage and prevent water from leaking, wear and deterioration due to long-term use may occur. Therefore, the secondary seal 16 needs to be replaced regularly due to the life of the elastomer, and it should be replaced regularly. It

However, even when only the secondary seal 16 needs to be replaced, the conventional internal pump is basically maintenance-free, and the pump impeller 4 and the drive shaft 3 are detached and attached, and the upper plug 21 is removed. Installation
Removal work is required. Moreover, the work of attaching / detaching the pump impeller 4 and the upper plug 21 cannot be carried out while the fuel assembly is being replaced, and the work must be waited.

Therefore, in the conventional internal pump, the replacement work of the secondary seal 16 is strongly affected by the fuel assembly replacement work and the control rod drive mechanism maintenance / inspection work, and the replacement of the secondary seal. Even when only doing, it is necessary to attach and detach the pump impeller 4 and the upper plug 21,
Because of the extra work that is not directly related to the original work of attaching and detaching the secondary seal 16, it takes a long time to perform the maintenance and inspection work of the internal pump, which causes the operating rate of the reactor to decrease. Was there.

The present invention has been made in consideration of the above-mentioned circumstances, and the time required for the maintenance and inspection work of the internal pump is shortened by separating the attachment / detachment work of the secondary seal mechanism from the pump impeller attachment / detachment work. An object of the present invention is to provide an internal pump attachment / detachment device that can improve the operating rate of a nuclear reactor.

Another object of the present invention is to make it possible to replace the secondary seal without attaching or detaching the pump impeller or the drive shaft, thereby simplifying and simplifying the replacement work of the secondary seal, which can be carried out in a short time. It is to provide a device for attaching and detaching the internal pump.

[0027]

In order to solve the above-mentioned problems, an internal pump attaching / detaching device according to the present invention is mounted on a lower mirror portion of a reactor pressure vessel as described in claim 1. An installed motor casing, a secondary seal mechanism attached to a shoulder portion of the motor casing, and a secondary seal handling tool that is inserted from below the motor casing and detachably connected to the secondary seal mechanism. The secondary seal handling tool includes an engagement releasing means for releasing the engagement between the secondary sealing mechanism and the motor casing, and forms a cylindrical space portion through which the drive shaft of the pump impeller can be inserted. It was done.

In order to solve the above-mentioned problems, an internal pump attaching / detaching device according to the present invention is claimed in claim 2.
As described above, the secondary sealing mechanism includes a sealing means for sealing between the motor casing and the drive shaft by an external fluid pressure action, and the secondary sealing mechanism is engaged and held in the shoulder circumferential groove of the motor casing. The secondary seal handling device has an engaging and holding means for connecting with a secondary seal handling device and a secondary seal handling device with an elevating device for raising and lowering a hollow shaft through which a drive shaft can be inserted, and an upper part of the hollow shaft as a secondary device. Connecting means for detachably connecting to the connecting means of the seal mechanism,
And a disengagement holding means for holding the engagement holding means of the secondary seal mechanism in a disengaged state. Further, as described in claim 3, the secondary seal handling tool includes a pump impeller. The drive shaft is provided with a tension applying means for applying a downward pulling force, and the mounting flange is provided with a water leak receiver and a drain line.

On the other hand, the internal pump handling method according to the present invention is intended to solve the above-mentioned problems.
As described in, at the time of maintenance and inspection of the internal pump, after removing the motor part from the motor casing downward, insert a secondary seal handling tool from below in the motor casing, and by this secondary seal handling tool, This is a method of performing maintenance and inspection of the secondary seal mechanism by attaching and detaching the secondary seal mechanism with the pump impeller and drive shaft attached.

The internal pump handling method according to the present invention is intended to solve the above-mentioned problems.
As described in (4), during the maintenance and inspection of the internal pump, the removal work of the secondary seal mechanism is separated from the removal work of the pump impeller and the drive shaft, and the secondary seal mechanism can be installed only from below the reactor pressure vessel. It is a method of attaching and detaching.

Further, according to the internal pump handling method of the present invention, in order to solve the above-mentioned problems, as described in claim 6, the pump impeller and the drive shaft are detached during the periodic inspection period of the reactor. Instead, the secondary seal mechanism is taken out from the lower side of the motor casing without being mounted, the secondary seal mechanism is maintained, inspected, maintained or replaced, and then the secondary seal mechanism is attached from the lower side of the motor casing.

[0032]

In the attachment / detachment device of the internal pump according to claim 1, a secondary seal handling tool which is inserted from the lower portion of the motor casing and is detachably connected to the secondary sealing mechanism is provided. Is provided with an engagement releasing means for releasing the engagement between the secondary sealing mechanism and the motor casing, and has formed a cylindrical space portion through which the drive shaft of the pump impeller can be inserted. The secondary sealing mechanism can be used to remove or install the secondary sealing mechanism from the motor casing. This desorption or replacement work of the secondary seal mechanism is performed below the reactor pressure vessel without being affected by refueling work and maintenance / inspection work of the control rod drive mechanism. It can be performed efficiently, and the work time required for maintenance and inspection of the internal pump can be greatly reduced. Therefore, the operating rate of the nuclear reactor can be improved.

Further, in this internal pump attaching / detaching device, the secondary seal mechanism can be replaced without removing the pump impeller and the drive shaft, so that the secondary seal mechanism can be replaced. It can be simplified and can be done efficiently in a short time and economically.

In the attachment / detachment device for an internal pump according to a second aspect of the present invention, the sealing means acting on the secondary sealing mechanism by an external fluid pressure and the engagement holding means for supporting the secondary sealing mechanism on the shoulder portion of the motor casing. And a means for connecting to the secondary seal handling tool, the hollow shaft elevating means capable of inserting the drive shaft into the secondary seal handling tool, the connecting means to the secondary seal mechanism, and the secondary seal mechanism. Since the engagement release holding means for holding the engagement release state is provided, the secondary seal mechanism can be removed and installed independently of the pump impeller attachment / detachment work. The time required can be greatly reduced, and the operating rate of the nuclear reactor can be improved.

In the internal pump attachment / detachment device according to the third aspect, the secondary seal handling device is provided with the tension applying means for applying a downward tensile force to the drive shaft.
By this tension applying means, the drive shaft can be stably held, while the sealability of the primary seal can be improved, and leakage of reactor water can be effectively prevented.

The leaked water can be easily drained to the outside of the motor casing through the drain line through the drain line.

In the internal pump handling method according to the fourth aspect, after the motor section is removed from the motor casing, the secondary seal handling tool inserted into the motor casing keeps the pump impeller and the drive shaft attached. Since the secondary seal mechanism can be removed and installed, maintenance and inspection of the secondary seal mechanism can be performed without removing the pump impeller and drive shaft, and the secondary seal mechanism can be removed and installed easily. It is possible to improve workability and significantly reduce work time.

In the internal pump handling method according to the fifth aspect, the work of attaching and detaching the secondary seal mechanism is independent of the work of attaching and detaching the pump impeller and the drive shaft. Since the work can be performed only from below the pressure vessel, the work of removing and installing the secondary seal mechanism can be simplified, the workability can be improved, and the work time can be shortened.

In the internal pump handling method according to the sixth aspect, the secondary seal mechanism can be efficiently and efficiently removed and installed even during refueling work during the periodic inspection of the reactor. Maintenance, inspection, maintenance or replacement work can be performed only from below the reactor pressure vessel.

[0040]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings.

In the Advanced Boiling Water Reactor (ABWR),
As shown in FIG. 1, a plurality of wet motor type internal pumps 23 are provided in the reactor pressure vessel 10 housed in the reactor containment vessel 22. The internal pump 23 is provided around the lower mirror part of the reactor pressure vessel 10, and by its pumping action, the reactor water in the reactor pressure vessel 10 is forcibly recirculated, and the core 2 surrounded by the core shroud 25 is
6 is actively supplying reactor water.

The core 26 is constructed by mounting a large number of fuel assemblies 27, while the reactor water heated by passing through the core 26 is separated into gas and liquid by a steam separator 28. The separated steam component is dried by the steam dryer 29 and becomes dry steam and is guided to the main steam system 30.

On the other hand, the liquid component separated by the steam separator 28 is guided to the annular downcomer portion 5 formed by the core shroud 25 and the inner peripheral wall of the reactor pressure vessel 10.
The water guided to the downcomer unit 5 is the internal pump 2
3 and is guided to the lower core plenum 31 and returned to the core 26 again.

The control rod 3 is provided between the fuel assemblies 27 of the core 26.
2 is moved in and out by the control rod drive mechanism 33, and the ABWR
It controls the start / stop of and the output control during operation.

On the other hand, the lower mirror portion 10a of the reactor pressure vessel 10
Since the overall structure of the internal pump 23 installed in FIG. 10 is the same as that shown in FIG. 10, the same reference numerals are given and the description thereof will be omitted.

At the time of maintenance and inspection of the internal pump 23, maintenance and inspection work is performed by using the attachment / detachment device 35 of the internal pump 23.

As shown in FIG. 2, the internal pump 23 has a secondary seal mechanism 3 on the shoulder 15 of the motor casing 9.
6 is installed. The secondary seal mechanism 36 is provided below the stretch tube nut 14 at a predetermined interval.

As shown in FIG. 3, the secondary seal mechanism 36 is provided with a ring-shaped or torus-shaped seal main body 37 which is liquid-tightly mounted on the shoulder inner peripheral wall of the motor casing 9 with an O-ring or the like. In 37, upper and lower ring-shaped main body pieces 38 and 39 that can be divided into two parts are fastened with tightening bolts 40 or the like to be liquid-tightly integrated with an O-ring or the like.

A wedge-shaped seal guide surface is formed on the inner peripheral side of the seal body 37 by the mating surfaces of the body pieces 38 and 39, and sealing means is provided in a wedge-shaped ring-shaped taper space 41 defined by the seal guide surfaces. Elastomer 4 as
3 are accommodated. The elastomer 43 is housed so as to project toward the inner peripheral side, while a fluid pressure such as air pressure or water pressure acts on the back side of the elastomer 43 from the secondary seal pressure pipe 17 via the communication passage 44. .

Further, a washer 45, which constitutes an engaging and holding means, is sandwiched between the seal body 37 by the upper and lower body pieces 38, 39. The washer 45 is composed of a disc spring or the like made of an elastic material, the inner peripheral side of which is sandwiched between the body pieces 38 and 39, and the outer peripheral side of the washer 45 engages with the peripheral groove 46 of the motor casing 9 to form a secondary sealing mechanism. Holds 36.

A connecting means 47 is provided below the seal body 37 of the secondary seal mechanism 36. The connecting means 47 comprises a disc-shaped engaging plate 48 and an engaging hole (groove) 49 integrally formed with the lower body piece 39 of the seal body 37, and the connecting means 47 has a secondary seal handling tool 50.
Is detachably connected.

The secondary seal handling tool 50 is inserted from below the motor casing 9 as shown in FIG. 2, and the mounting flange 52 of the handling tool body 51 is attached to the lower flange portion 9a of the motor casing 9 by tightening bolts 53 and the like. It is fixed by a fastening means and is installed in a liquid-tight manner by a sealing means such as an O-ring 54.

The handling tool 51 is integrally provided with a sleeve-shaped or tubular holding cylinder 55 which rises from the mounting flange 52, and a hydraulic cylinder mechanism 57 as an elevating means for moving the hollow shaft 56 up and down is provided on the holding cylinder 55. ing. The hydraulic cylinder mechanism 57 is divided into an upper cylinder chamber 60 and a lower cylinder chamber 61 by a piston 58 provided on the lower outer peripheral side of the hollow shaft 56.
Hydraulic pressure is supplied to 0 and 61 through hydraulic pipes 62 and 63. Even if the lifting means is a cylinder mechanism using water pressure or air pressure instead of the hydraulic cylinder mechanism 57,
A motor drive mechanism in which a motor and a screw shaft are combined may be used.

The secondary seal handling tool 50 has a tubular space 65 through which the drive shaft 3 can be inserted by a holding cylinder 55 and a hollow shaft 56. The teeth 66 are formed, and the outer teeth 66 mesh with the drive pinion 68 attached to the output shaft of the motor 67, and the rotation mechanism 6 of the hollow shaft 56.
9 is composed. By driving the rotating mechanism 69, the hollow shaft 56 is driven to rotate about the shaft axis.

Further, an engaging cylinder 70 is installed on the upper part of the hollow shaft 56, and a plurality of hook-shaped engaging claws 71 are provided on the upper part of the engaging cylinder 70 as shown in FIG. The engaging claw 71 may be formed directly on the top of the hollow shaft 56. The engaging claw 71 and the rotating mechanism 69 constitute a connecting means 72 for detachably connecting the upper portion of the hollow shaft 56 to the secondary sealing mechanism 36. In addition, the engagement cylinder 7
0 or the hollow shaft 56 and the hydraulic cylinder mechanism 57, which is an elevating means, constitute an engagement releasing means for the secondary sealing mechanism 16.

Further, the engaging cylinder 70 has a secondary seal mechanism 36.
Disengagement holding means 74 for holding the engagement holding means 45 in the disengaged state is provided. The disengagement holding means 74 may be provided on the upper portion of the hollow shaft 56. The engagement release holding means 74 includes a cover cylinder 75 slidably fitted on the engagement cylinder 70. The cover cylinder 75 is always urged upward by a spring 76 and is formed at the upper end of the cover cylinder 76. The cover sleeve 77 has an outer diameter that is slidably inserted into the shoulder portion 15 of the motor casing 9. The cover sleeve 77 has a taper formed at the tip end portion so as to expand toward the tip end, and due to this taper, the secondary seal mechanism 3
When the engagement holding means 45 of No. 6 is disengaged, the washer 45, which is the engagement holding means, is smoothly guided into the cover spring 77.

On the other hand, in the secondary seal handling tool 50, as shown in FIG. 2, a tension applying means 78 for applying a tensile force to the drive shaft 3 is provided at the center of the mounting flange 52.
The tension applying means 78 is provided with an adjusting bolt 79 which is liquid-tightly mounted in the central hole of the mounting flange 52, and the tip end side of the adjusting bolt 79 is screwed to an impeller stud 80 extending downward from the drive shaft 3. Then
By rotating the adjusting bolt 79, the impeller stud 80 is pulled downward, and a downward pulling force is applied to the drive shaft 3. Due to this tensile force, in the internal pump 23, as shown in FIG. 10, the primary seal makes a metal contact and seals the reactor water.

Thus, the internal pump 23 is the elastomer 4 which constitutes the sealing means of the secondary sealing mechanism 36.
Due to the service life of 3, regular replacement is required. Even when the elastomer of the secondary seal mechanism 16 is replaced in the conventional internal pump, the pump impeller attachment / detachment work and the upper plug 21 attachment / detachment work are required. During the replacement work of 27, the secondary seal mechanism 16 could not be removed or attached.

Attaching / detaching device 3 for this internal pump 23
5, the secondary seal handling tool 50 is installed on the motor casing 9, and the secondary seal handling tool 50 is operated to remove and install the secondary seal mechanism 36. The removal work of the pump impeller 4 and the upper plug 21 are performed. It can be performed independently from the attachment / detachment work of (1) and is performed only from the lower side of the reactor pressure vessel 10 regardless of the attachment / detachment work of the pump impeller 4.

Next, the operation of the attaching / detaching device 35 for the internal pump 23 will be described.

Attaching / detaching device 3 for this internal pump 23
5, when the secondary seal mechanism 36 is attached / detached, the fluid pressure from the secondary seal pressurizing pipe 17 is applied to the back side of the secondary seal mechanism 36 to cause the elastomer 43, which is the sealing means, to drive the drive shaft. The side 3 is pressed against and sealed to prevent leakage of reactor water in the reactor pressure vessel 10.

In this state, the closing flange 20 of the internal pump 23 is removed, the motor section 1 is taken out from below the motor casing 9, and the motor section 1 is inspected and maintained.

After removing the motor unit 1 from the motor casing 9, the secondary seal handling tool 50 is attached to the motor casing 9.
Insert the mounting flange 52 from the bottom of the
Then, the secondary seal handling tool 50 is fixed to the lower part of the motor casing 9 and the secondary seal handling tool 50 is installed on the motor casing 9. At this time, the impeller stud 80 extending downward from the drive shaft 3 is screwed by the tension applying means 78 to apply a downward pulling force to the drive shaft 3 to strengthen the adhesion at the primary seal. In this state, the sealing function of the secondary sealing mechanism 36 is released. As shown in FIG. 5, the work of removing and installing the secondary seal mechanism 36 is performed while the pump impeller 4 and the drive shaft 3 are mounted.

Next, when the hydraulic cylinder mechanism 57 of the secondary seal handling tool 50 is driven to move the hollow shaft 56 upward, from the state shown in FIG.
1 enters the connecting means 47 below the secondary sealing mechanism 36. Specifically, the engaging claw 71 enters into the elongated hole of the engaging plate 48 of the secondary sealing mechanism 36. The engaging mechanism 71 is rotated by driving the rotating mechanism 69 while the engaging claw 71 is inserted into the elongated hole of the engaging plate 48, and the engaging claw 71 is engaged with the engaging hole 49. By this engagement, the engaging claw 71 is connected to the connecting means of the secondary sealing mechanism 36 and locked, and
As shown in (B), the drawing becomes impossible.

The secondary seal handling tool 50 is attached to the secondary seal mechanism 3
When the hydraulic cylinder mechanism 57 is driven again in the state of being connected to the connecting means 47 of No. 6, and the hollow shaft 56 is further raised by a required amount, the hollow shaft 56 pushes up and lifts the entire secondary seal mechanism 36. By lifting the secondary seal mechanism 36, the washer 45 of the engagement holding means
Bends inward while being disengaged from the circumferential groove 46 of the motor casing 9. As a result, the washer 45 and the peripheral groove 46 of the motor casing 9 are disengaged, and at the same time, the cover cylinder 75 is lifted by the spring action of the spring 76, and the cover sleeve 77 closes the peripheral groove 46. The state shown in FIG. At this time, the hydraulic cylinder mechanism 57 moves the engagement holding means 4
5 functions as a disengagement means.

With the cover sleeve 77 of the cover cylinder 75 closing the circumferential groove 46, the hydraulic cylinder mechanism 5 serving as an elevating means.
7 is driven again to move the hollow shaft 56 downward.
When the hollow shaft 56 is moved downward, the cover sleeve 77 of the cover cylinder 75 is moved by the spring force of the spring 76 into the circumferential groove 4.
6, the washer 45 is guided and inserted into the cover sleeve 77 while being bent.

The cover sleeve 7 of the cover cylinder 75 is moved by the downward operation of the hollow shaft 56 by the hydraulic cylinder mechanism 57.
The secondary seal mechanism 36 does not interfere with the shoulder portion 1 of the motor casing 9 because the spring 7 prevents the washer 45 from expanding.
5 and is guided to the body portion 18 of the motor casing 9 (see FIG. 6D).

Thereafter, while the fastening bolt 53 of the secondary seal handling tool 50 is removed, the tension applying means 78 is operated to release the tension applied to the drive shaft 3, and a screw mechanism (not shown) is driven by the drive motor. A base (not shown) is lowered, and the secondary seal handling tool 50 installed on the base is pulled out from below the motor casing 9. As a result, the work of removing the secondary seal mechanism 36 is completed.

After that, the secondary seal mechanism 36 taken out
The maintenance, inspection, and maintenance are performed, and the elastomer 43, which is the sealing means that has reached the end of its life, is replaced. After the maintenance and inspection of the secondary seal mechanism 36, the secondary seal mechanism 36 is attached to the shoulder portion 15 of the motor casing 9 again.

The mounting work of the secondary seal mechanism 36 is performed as follows.

Hollow shaft 56 of secondary seal handling tool 50
Is held at the lowered position by the hydraulic cylinder mechanism 57, the cover cylinder 75 is removed in this state, and the secondary seal mechanism 36 is installed in a state of being connected by the engaging claw 71.

Next, the drive motor is started to rotate the screw mechanism (both not shown) to raise the base, and the secondary seal handling tool 50 installed on the base is inserted into the motor casing 9. Then, the secondary seal handling tool 50 is fixed to the motor casing 9 with the fastening bolts 53 and installed.

Further, the impeller stud 80 extending from the drive shaft 3 of the pump impeller 4 is attached to the tension applying means 78.
The drive shaft 3 is fixed by being screwed to the adjusting bolt 79 of. After fixing the drive shaft 3, the hydraulic cylinder mechanism 57 is driven to raise the hollow shaft 56, and the washer 45, which is the engagement holding means of the secondary seal mechanism 36, is moved in contact along the inner peripheral wall of the shoulder portion of the motor casing 9. , The peripheral groove 46 of the motor casing 9 is engaged. This washer 4
Due to the engagement of No. 5, the secondary seal mechanism 36 is forcibly attached to the shoulder portion 15 of the motor casing 9 and held in engagement.

After that, the connection state between the secondary seal handling tool 50 and the secondary seal mechanism 36 is released by rotational driving, and in this released state, the fastening bolt 53 of the secondary seal handling tool 50 is removed and a drive not shown is carried out. The secondary seal handling tool 50 is pulled out from below the motor casing 9 by driving the motor, and the mounting work of the secondary seal mechanism 36 is completed.

After the mounting of the secondary seal mechanism 36 is completed,
By inserting the motor portion 1 from below the motor casing 9 and closing the closing flange 20 at the lower portion of the motor casing 9, the maintenance and inspection work of the internal pump 23 is completed.

Next, a second embodiment of the attachment / detachment device for the internal pump will be described.

FIGS. 7 to 9 show a second embodiment of the attachment / detachment device for the internal pump. Attachment / detachment device 35A for the internal pump 23 shown in the second embodiment.
From the bottom to the motor casing 9 secondary seal handling tool 50
A is inserted and installed in a liquid-tight manner via the mounting flange 52.

The secondary seal handling tool 50A has a mounting flange 5
2 has a holding cylinder 55 standing upright, and the hollow shaft 56 is housed in the holding cylinder 55 by a lifting means 85 so as to be lifted and lowered. The elevating means 85 is formed by, for example, a screw shaft mechanism 86 with a motor, and the hollow shaft 56 is moved up and down by rotationally driving the screw shaft 88 by a reversible drive motor 87. A tubular space 90 into which the drive shaft 3 of the pump impeller 4 can be inserted is formed in the hollow shaft 56 and the holding cylinder 55.

A bearing 9 is provided above the hollow shaft 56.
The engaging cylinder 92 is rotatably provided around the central axis via the rotary mechanism 9 for rotating the engaging cylinder 92.
3 is provided on top of the hollow shaft 56. Rotation mechanism 9
3 is configured by engaging a drive pinion 95 attached to the output shaft of the drive motor 94 with engagement teeth 96 provided on the outer peripheral side of the engagement cylinder 92. In the rotation mechanism 93, the drive motor 94 may be provided on the engagement cylinder 92 side and the engagement teeth may be provided on the hollow shaft 56 side. The rotation mechanism 93 constitutes an engagement release holding means for releasing the engagement holding means 101 of the secondary seal mechanism 100 shown in FIG. Since the rotation mechanism 93 only needs to rotate the engagement cylinder 92, the rotational inertia amount may be small.

On the other hand, an engaging claw 95 is provided on the top of the engaging cylinder 92. The engaging claw 95 is formed in a hook shape similar to that shown in FIG. 4, for example. Reference numeral 79 is an adjusting bolt of the tension applying means 78. Since the shape of the adjusting bolt 79 is not different from that shown in FIG. 2, the same reference numeral is given and its description is omitted.

Further, the shoulder portion 15 of the internal pump 23
The secondary seal mechanism 100 mounted on the motor has a ring-shaped structure shown in FIG. 8 and is mounted on the shoulder portion 15 of the motor casing 9 in a liquid-tight manner. The secondary seal mechanism 100 has a ring-shaped seal main body 102, and the seal main body 102 can divide the ring-shaped upper main body piece 103, the lower main body piece 104, and the support body 105 by tightening the tightening bolts 106 together. It is assembled and integrated.

The seal body 102 of the secondary seal mechanism 100
A wedge-shaped seal guide surface is provided on the inner peripheral side of both main body pieces 10.
The wedge-shaped ring-shaped taper space 107 is formed by the mating surfaces of 3, 104 and is defined by the seal guide surface.
An elastomer 108 as a sealing means is accommodated in the. The elastomer 108 is housed so as to be able to project to the inner peripheral side, while a fluid pressure such as air pressure or water acts on the back side of the elatosumer 108 from the secondary seal pressure pipe 17 via the communication passage 109. Due to the action of this fluid pressure, the elastomer 1
08 is pushed out and comes into pressure contact with the drive shaft 3 to perform a sealing action.

On the other hand, a support 105 is attached to the lower part of the secondary seal mechanism 100, and a slide ring 110 is supported on the support 105 so as to be slidable in the rotational direction. The slide amount of the slide ring 110 is the tightening bolt 1
The slide ring 110 is formed with a plurality of engagement holes 112 that can be engaged with the engagement claws 95 of the engagement cylinder 92 while being regulated by the long holes 111 that engage with 06. Further, a plurality of protrusions protruding outward in the radial direction are formed on the slide ring, and a fixing pin 114 is provided on the free end side of the protrusions. Each fixing pin 114 is slidably engaged with an elongated hole 116 formed in an arcuate engagement arm 115. Each long hole 116 intersects with the radial direction at a predetermined angle so as to have a spiral expansion.

Further, each engagement arm 114 has a seal body 1
It is rotatably supported around a support pin 117 fixed to 02. In practice, each engagement arm 115 has its elongated hole 11
6 and the fixed pin 114 are engaged with each other, so that the fixed pin 114 and the fixed pin 114 are horizontally swingably supported around the support pin 117. Support pin 117
May be provided on the lower surface of the body piece 103 of the seal body 102 or on the support 105.

From the state shown in FIG. 9 (A), the engaging arm 115 swings around the support pin 117 by rotating the slide ring 110 in the counterclockwise direction to expand.
The state shown in FIG. 9B is obtained. In the expanded state shown in FIG. 9B, the free end side of each engagement arm 115 engages with the circumferential groove 46 of the shoulder portion 15 of the motor casing 9, and the secondary seal mechanism 1
00 is held. Motor casing 9
In order to stably hold the secondary sealing mechanism 100 on the shoulder portion 15 of the, the spring is interposed between the slide ring 110 and the support body 105, and the slide ring 110 is expanded in the direction in which each engagement arm 115 expands. The spring may be constantly biased.

The secondary sealing mechanism 100 includes each engaging arm 11
5 is made openable by the rotation operation of the slide ring 110, and the engagement holding means 101 is constituted by expanding the engagement arms 115 to engage with the circumferential groove 46 of the motor casing 9. By this engagement holding means 101,
The secondary seal mechanism 100 includes a shoulder portion 15 of the motor casing 9.
It is fixedly held at.

Further, the secondary seal mechanism 100 is configured as shown in FIGS. 8 and 9, so that the seal body 1
A connecting means 11 to the secondary seal handling tool 50A at the bottom of 02.
9 are configured. This connecting means 119 is used for the support 105.
The engaging hole formed in the engaging hole 1 of the slide ring 110.
12 and the engaging claws 95 of the secondary seal handling tool 50A can be inserted through these engaging holes 112.

Secondary seal mechanism 10 shown in FIGS. 8 and 9.
The attachment / detachment work of 0 is performed as follows.

When removing the secondary seal mechanism 100 provided in the internal pump 23, first, a fluid pressure is applied to the back side of the secondary seal mechanism 100 to press the elastomer 108, which is the sealing means, against the drive shaft 3. Contact and seal to prevent leakage of reactor water.

With the secondary seal mechanism 100 in operation, the closing flange 20 of the motor casing 9 is removed and the motor unit 1 is taken out from below the motor casing 9. The motor unit 1 is taken out using a replacement rotary mount (not shown) of the control rod drive mechanism.

After removing the motor unit 1 from the motor casing 9, a drive motor (not shown) is driven to rotate and drive a screw mechanism to raise a base (not shown), and the secondary unit installed on the base is driven. The seal handling tool 50A is inserted into the motor casing 9 from below. At this time, the drive shaft 3 is inserted into the hollow shaft 56 of the secondary seal handling tool 50A so as to be guided.

After inserting the secondary seal handling tool 50A, the secondary seal handling tool 50A is fixed to the motor casing 9 by the fastening bolts 53 and installed, while the impeller stud 80 extending from the drive shaft 3 of the internal pump 23 is installed.
An adjusting bolt 79 as a tension applying means is screw-connected to the drive shaft 3 to apply a downward pulling force to the drive shaft 3 to strengthen the sealing function of the primary seal. By the screw connection of the adjusting bolt 79, the drive shaft 3 can be stably held without lateral swing.

From this state, the drive motor 8 of the elevating means 85
7 is driven to raise the hollow shaft 56, and the engaging claw 85 provided on the upper portion of the hollow shaft 56 is inserted into the elongated hole of the support body 105 formed on the lower portion of the secondary sealing mechanism 100. The engaging claws 85 and the elongated holes respectively form a connecting means.

After inserting the engaging claw 95 of the secondary seal handling tool 50A into the elongated hole constituting the connecting means 119 of the secondary seal mechanism 100, the rotating mechanism 93 is activated to see the engaging claw 95 from above. When rotated in the clockwise direction, the engaging claws 95 are locked to the support body 105 in a non-pullable manner and connected. Also,
When the slide ring 110 is rotated clockwise, the engagement arm 115 is moved from the expanded state shown in FIG.
It can be brought to the stored state shown in (A).

By rotating the slide ring 110 in the clockwise direction, the fixing pin 114 is moved to the long hole 11 of each engaging arm 115.
6, the engagement arms 115 are drawn inward to be disengaged from the circumferential groove 46 of the motor casing 9, and the engagement holding means 1 of the motor casing 9 and the secondary seal mechanism 100 is retained.
01 is released.

With the secondary seal mechanism 100 disengaged, the drive motor 87 of the elevating means 85 is driven to lower the hollow shaft 56. At this time, since the secondary seal mechanism 100 is disengaged from the circumferential groove 46 of the motor casing 9, the secondary seal mechanism 100 is taken out downward without any obstacle, and the body portion 18 of the motor casing 9 is removed.
Will be guided to.

In this state, the fastening bolt 53 of the secondary seal handling tool 50A is removed, and a drive motor (not shown) is driven to lower the base by a screw mechanism, so that the secondary seal handling tool installed on the base. 50A for motor casing 9
It can be pulled down further. As a result, the removal of the secondary seal mechanism 100 is completed, and the secondary seal mechanism 10 is removed.
After that, maintenance inspection or replacement is performed for 0, and after this maintenance inspection or replacement, the mounting work of the secondary seal mechanism 100 is started.

In the mounting work of the secondary seal mechanism 100, the elevating means 85 is driven to set the hollow shaft 56 to the lower position, while the engaging arm 115 of the secondary seal mechanism 100 rotates the slide ring 110. The engaging claw 95 is set so that the engaging claw 95 can be inserted into the elongated hole of the support 105. Then, the secondary sealing mechanism 100
9 is installed on the secondary seal handling tool 50A, and the entire secondary seal mechanism 100 is rotated counterclockwise when viewed from above.
The engaging arm 115 is housed as shown in FIGS.

Next, a drive motor (not shown) is driven to raise a base (not shown) by a screw mechanism, and the secondary seal handling tool 50A installed on the base is inserted into the motor casing 9 from below. To do. After the secondary seal handling tool 50A is inserted, the secondary seal handling tool 50A is fixed to the lower flange portion 9a of the motor casing 9 with the fastening bolts 53,
install. When the secondary seal handling tool 50A is installed, the adjusting bolt 79 of the tension applying means 78 is screwed to the impeller stud 80 of the drive shaft 3 so that the drive shaft 3 is not screwed.
Keep it stable.

After the drive shaft 3 is fixedly held, the raising / lowering means 85 of the secondary seal handling tool 50A is driven to move the hollow shaft 56 upward so as to reach the shoulder portion 15 of the motor casing 9 of the secondary seal mechanism 100. .

After the secondary sealing mechanism 100 reaches the predetermined position of the motor casing 9, the rotating mechanism 93 is driven to rotate the engagement cylinder 92 counterclockwise when viewed from above. By this rotation of the engagement cylinder 92, the engagement arm 115 expands to engage with the circumferential groove 46 of the motor casing 9, and the secondary sealing mechanism 100 is attached to the shoulder portion 15 of the motor casing 9 at a predetermined position. The engaging claw 95 can be pulled out from the long hole which constitutes the connecting means 119 of the support 105.

After that, by removing the fastening bolt 53 of the secondary seal handling tool 50A and driving a drive motor (not shown), the secondary seal handling tool 50A can be pulled out from the lower portion of the motor casing 9 and the secondary seal mechanism. The work of attaching 100 is completed.

According to this internal pump attachment / detachment device, the attachment / detachment work of the secondary seal mechanisms 36, 100 can be carried out separately from the attachment / detachment work of the maintenance-free pump impeller 4 and the attachment / detachment work of the upper plug 21. The secondary seal mechanism can be detached and attached only by the work below the reactor pressure vessel 10, and can be independently performed during the fuel assembly replacement work.

Further, it is not necessary to attach / detach the maintenance-free pump impeller 4 and the drive shaft 3 even during the periodical inspection of the ABWR, and the secondary seal mechanisms 36, 100 can be detached and attached while they are still attached. You can During the periodic inspection of the ABWR, the elastomer 43, 108, which is the sealing means, needs to be replaced depending on the service life thereof. Therefore, the elastomer 43, 108, which is the sealing means, is replaced when the secondary sealing mechanisms 36, 100 are attached and detached. Be done.

In the second embodiment of the attachment / detachment device for the internal pump according to the present invention, an example in which the engagement cylinder is rotated above the hollow shaft via the bearing is shown. A rotating mechanism for rotating the is not necessarily required. If the hollow shaft itself can be rotated by the rotating mechanism with respect to the protective cylinder, the engaging cylinder and the bearing are unnecessary. In this case, the engaging claw may be provided directly on the upper part of the hollow shaft.

[0106]

As described above, in the attachment / detachment device for the internal pump according to the first aspect, the secondary seal handling tool inserted from the lower portion of the motor casing and detachably connected to the secondary seal mechanism. This secondary seal handling tool is provided with an engagement releasing means for releasing the engagement between the secondary sealing mechanism and the motor casing, and since the tubular space portion in which the drive shaft of the pump impeller can be inserted is formed. With the drive shaft of the pump impeller attached, the secondary seal mechanism can be removed or attached to the motor casing with the secondary seal handling tool. Desorption or replacement work of this secondary sealing mechanism is affected by refueling work and maintenance / inspection work of the control rod drive mechanism below the reactor pressure vessel, but is independent of refueling work and maintenance / inspection work. It can be performed efficiently, and the work time required for maintenance and inspection of the internal pump can be greatly reduced. Therefore, the operating rate of the nuclear reactor can be improved.

Further, in this internal pump attaching / detaching device, the secondary seal mechanism can be replaced without removing the pump impeller and the drive shaft, so that the secondary seal mechanism can be replaced. It can be simplified and can be done efficiently in a short time and economically.

In the attachment / detachment device of the internal pump according to the second aspect of the present invention, the sealing means that acts on the secondary sealing mechanism by the fluid pressure from the outside and the engagement holding means that supports the secondary sealing mechanism on the shoulder of the motor casing. And a means for connecting to the secondary seal handling tool, the hollow shaft elevating means capable of inserting the drive shaft into the secondary seal handling tool, the connecting means to the secondary seal mechanism, and the secondary seal mechanism. Since the engagement release holding means for holding the engagement release state is provided, the secondary seal mechanism can be removed and installed independently of the pump impeller attachment / detachment work. The time required can be greatly reduced, and the operating rate of the nuclear reactor can be improved.

In the internal pump attaching / detaching device according to the third aspect, the secondary seal handling device is provided with the tension applying means for applying a downward tensile force to the drive shaft.
By this tension applying means, the drive shaft can be stably held, while the sealability of the primary seal can be improved, and leakage of reactor water can be effectively prevented.

Further, the leaked water can be easily drained to the outside of the motor casing by the drain line of the leak receiver.

In the internal pump handling method according to the fourth aspect, after the motor section is removed from the motor casing, the secondary seal handling tool inserted into the motor casing is used to keep the pump impeller and the drive shaft attached. Since the secondary seal mechanism can be removed and installed, maintenance and inspection of the secondary seal mechanism can be performed without removing the pump impeller and drive shaft.
It is possible to remove the secondary seal mechanism, simplify the installation work, improve workability, and significantly reduce the work time.

In the internal pump handling method according to the fifth aspect, the work of removing the secondary seal mechanism is independent of the work of removing the pump impeller and the drive shaft. Since the work can be performed only from below the pressure vessel, the work of removing and installing the secondary seal mechanism can be simplified, the workability can be improved, and the work time can be shortened.

In the internal pump handling method according to the sixth aspect, the secondary seal mechanism can be efficiently and efficiently removed and installed even during refueling work during the periodic inspection of the reactor. Maintenance, inspection, maintenance or replacement work can be performed only from below the reactor pressure vessel.

[Brief description of drawings]

FIG. 1 is a principle diagram showing an improved boiling water nuclear reactor equipped with an internal pump.

FIG. 2 is a vertical cross-sectional view showing an embodiment of an attachment / detachment device for an internal pump according to the present invention.

FIG. 3 is a partial cross-sectional view showing an engagement relationship between a secondary seal handling tool and a secondary seal mechanism provided in the attachment / detachment device for an internal pump according to the present invention.

FIG. 4 is a perspective view showing a connecting means of a secondary seal handling tool provided in the attachment / detachment device for an internal pump according to the present invention.

FIG. 5 is a cross-sectional view showing a handleable state of a secondary seal mechanism provided in the attachment / detachment device for an internal pump according to the present invention.

6A to 6D are views showing a procedure for removing the secondary seal mechanism using the attachment / detachment device of the internal pump according to the present invention.

FIG. 7 is a vertical cross-sectional view showing another embodiment of the attachment / detachment device for an internal pump according to the present invention.

8 is a partial cross-sectional view showing the engagement relationship between the secondary seal mechanism and the secondary seal handling tool of the internal pump shown in FIG.

9 (A) and 9 (B) are plan views showing an inactive state (stored state) and an operating state (expanded state) of the engagement holding means of the secondary seal mechanism shown in FIG. 8, respectively.

FIG. 10 is a vertical cross-sectional view showing an internal pump provided in the improved boiling water reactor.

FIG. 11 is a vertical cross-sectional view showing a state in which a conventional secondary sealing mechanism using an internal pump can be handled.

[Explanation of symbols]

 1 Motor Section 2 Pump Section 3 Drive Shaft 4 Pump Impeller 5 Downcomer Section 6 Diffuser 7 Stator 8 Rotor 9 Motor Casing 10 Reactor Pressure Vessel 11 Nozzle 13 Stretch Tube 14 Stretch Tube Nut 15 Motor Shoulder 16 Secondary Sealing Mechanism 17 Secondary seal pressurizing pipe 18 Body of motor casing 19 Cooling water circulation pipe 20 Closing (lid) flange 21 Upper plug 22 Reactor containment vessel 23 Internal pump 24 Core shroud 26 Core 32 Control rod 33 Control rod drive mechanism 35, 35A Internal pump attachment / detachment device 36 Secondary sealing mechanism 37 Seal main body 38, 39 Main body piece 40 Tightening bolt 41 Tapered space 43 Elastomer 45 Washer (engagement holding means) 46 Circumferential groove 47 Coupling means 50 Secondary seal Handling tool 51 Handling tool body 52 Mounting flange 55 Holding cylinder 56 Hollow shaft 57 Hydraulic cylinder mechanism (elevating / disengaging means) 58 Piston 60, 61 Cylinder chamber 65 Cylindrical space 67 Motor 68 Drive pinion 69 Rotation Mechanism 70 Engagement Cylinder (Disengagement Means) 71 Engagement Claw 72 Coupling Means 74 Engagement Retaining Means 78 Tension Applying Means 79 Adjusting Bolt 85 Elevating Means 86 Screw Shaft Mechanism 87 Drive Motor 88 Screw Shaft 90 Cylindrical Space 91 Bearing 92 Engagement cylinder 93 Rotation mechanism (disengagement holding means) 95 Engaging claw 100 Secondary sealing mechanism 101 Engagement holding means 102 Seal body 103 Upper body piece 104 Lower body piece 105 Support body 106 Tightening bolt 107 Lenk ring shape Taper space 108 gills Stormer 110 Slide ring 111 Long hole 112 Engaging hole 114 Fixing pin 115 Engaging arm 116 Long hole 117 Support pin 119 Connecting means

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroyuki Nojima 4-4 Suehiro-cho, Tsurumi-ku, Yokohama-shi, Kanagawa Stock company Toshiba Keihin office

Claims (6)

[Claims] 1. A motor casing vertically mounted on a lower mirror portion of a reactor pressure vessel, a secondary seal mechanism mounted on a shoulder portion of the motor casing, and a second casing inserted from below the motor casing. And a secondary seal handling tool detachably coupled to the secondary sealing mechanism, wherein the secondary sealing handling tool includes an engagement releasing means for releasing the engagement between the secondary sealing mechanism and the motor casing, An internal pump attachment / detachment device, characterized in that a tubular space is formed through which a drive shaft of a pump impeller can be inserted. 2. A secondary sealing mechanism for sealing between a motor casing and a drive shaft by an external fluid pressure action, and a secondary sealing mechanism engaged with and held in a shoulder groove of a motor casing. While the engaging and holding means and the connecting means for connecting the secondary seal handling tool to the lower part are provided, the secondary seal handling tool is an elevating means for raising and lowering the hollow shaft through which the drive shaft can be inserted, and a secondary seal for the upper part of the hollow shaft. 2. The internal pump according to claim 1, further comprising: connecting means that is detachably connected to the connecting means of the mechanism; Detachable device. 3. The secondary seal handling device according to claim 1 or 2, wherein the drive shaft of the pump impeller is provided with a tension applying means for applying a downward pulling force, and the mounting flange is provided with a water leakage receiver and a drain line. Internal pump attachment / detachment device. 4. During maintenance and inspection of the internal pump, after removing the motor section from the motor casing downward, a secondary seal handling tool is inserted into the motor casing from below and the secondary seal handling tool is used to pump the pump. A method for handling an internal pump, characterized in that the secondary seal mechanism is attached and detached with the impeller and drive shaft attached, and the secondary seal mechanism is inspected and maintained. 5. The secondary seal mechanism is detached and attached from the pump impeller and drive shaft during the maintenance and inspection of the internal pump, and the secondary seal mechanism is attached and detached only from below the reactor pressure vessel. A method of handling an internal pump, characterized by: 6. The secondary seal mechanism is taken out from the lower side of the motor casing with the pump impeller and the drive shaft not attached and detached during the periodic inspection period of the nuclear reactor, and the secondary seal mechanism is maintained, inspected, maintained or replaced. And then a secondary sealing mechanism is attached from below the motor casing.