JP6466113B2 - Internal pump and inspection method - Google Patents

Description

  The present invention relates to an internal pump and an inspection method thereof, and more particularly, to an internal pump used for circulating a reactor coolant in an improved boiling water reactor and an inspection method thereof.

  In the improved boiling water reactor (ABWR), a plurality of internal pumps are installed at the bottom of the reactor pressure vessel in order to circulate the reactor coolant (reactor water).

  This type of internal pump houses an impeller shaft mounted on the upper end side and an underwater motor for driving the impeller mounted on the lower end side, and an underwater motor and an impeller shaft. And a motor cover for sealing the bottom of the motor casing.

  When inspecting the internal pump, it is necessary to take out the submersible motor from the motor casing downward, so the motor cover is removed from the bottom of the motor casing. When removing the motor cover, in order to prevent the reactor water from leaking outside, the secondary seal device provided on the outer peripheral side of the impeller shaft is operated to seal the reactor water. Here, when taking out the submersible motor, the impeller and the impeller shaft are not supported by the bearing and are lowered downward, and the lower surface of the flange above the impeller shaft is placed on the upper end portion of the stretch tube. At this time, a primary seal that prevents external leakage of the reactor water is formed by the metal surface contact.

  And if it is going to replace | exchange a secondary seal apparatus in the state which removed the motor cover and the submersible motor, the reactor water which was not completely sealed with the primary seal leaks outside. Therefore, the replacement of the secondary seal device is usually performed as follows.

  That is, when replacing the secondary seal device, generally, the secondary seal device is first operated to drain the water in the motor casing, the motor cover is removed, the submersible motor is taken out, and then the lower end of the motor casing is removed. Close with the closing plate. After that, after the operation of the secondary seal device is canceled, the impeller and the impeller shaft are extracted upward, and the opening of the diffuser installed on the upper surface of the boss portion protruding from the inner surface of the reactor pressure vessel is closed by a closing plug. Close and drain the reactor water that has entered the motor casing again. Then, after removing the closing plate at the lower end of the motor casing, the secondary seal device is replaced.

  As described above, it is usually necessary to remove the impeller and the impeller shaft even when only inspecting the secondary sealing device. However, the work of removing the impeller and the impeller shaft requires a large number of work steps.

  Also, since rubber products are generally more susceptible to deterioration than metal parts, the inspection cycle of equipment such as impeller shafts is set according to the inspection cycle of secondary seal devices that use rubber seal members. Will increase. For this reason, in accordance with the inspection cycle of the secondary seal device that is shorter than the inspection cycle of the equipment such as the impeller shaft, the inspection of the equipment including the work of removing the impeller shaft and the like that requires a large work man-hour is performed. Reactor availability decreases.

  On the other hand, the technique which replaces | exchanges a secondary seal apparatus, without removing an impeller and an impeller shaft is disclosed (refer patent document 1, 2).

  The technique described in Patent Document 1 uses a secondary seal exchange device having a mechanism for applying a downward tensile force to the impeller shaft. That is, with the motor cover and submersible motor removed and the impeller shaft attached, a secondary seal replacement device is installed at the bottom of the motor casing, and a downward tensile force is applied to the impeller shaft to seal the primary seal. Replace the secondary seal with the condition improved.

  The technique described in Patent Document 2 uses a closing unit that seals the bottom of the motor casing, and a secondary seal changer that incorporates a remotely manipulator. That is, with the motor cover and submersible motor removed and the impeller shaft attached, a secondary seal changer is installed at the bottom of the motor casing, and a manipulator that can be operated remotely is used to place the secondary seal in the closing unit. Replace the seal.

JP-A-8-68887 JP 2013-53937 A

  However, in the technique described in Patent Document 1, the secondary seal exchange device requires a complicated structure, and the manufacturing cost increases. Further, in the technique described in Patent Document 2, the secondary seal exchange device requires a complicated structure, which increases the size of the device and increases the manufacturing cost.

  The present invention has been made in consideration of the circumstances of the prior art as described above, and can be used to easily check the secondary seal device with a simple and compact configuration without removing the impeller and the impeller shaft. It is an object to provide a null pump and an inspection method thereof.

In order to solve the above-mentioned problems, an internal pump according to the present invention includes an impeller shaft that is mounted on the lower end side with an impeller that is mounted on the upper end side, and an underwater motor that drives the impeller is mounted on the lower end side. , Provided at the bottom of the reactor pressure vessel and extending downward, a casing that houses the submersible motor and the impeller shaft, and a casing that is provided in the casing and seals between the impeller shaft and the casing. A plurality of secondary seal devices that are actuated by pressurized water are provided in the casing, wherein a plurality of installed portions are formed in the axial direction of the impeller shaft. To do.

  Further, the internal pump inspection method according to the present invention includes the step of installing at least one secondary seal device in the installation portion of the internal pump and operating the internal pump; At the time of inspection of the null pump, another secondary seal device is additionally installed below the secondary seal device installed in the installed part, or the lowest one among those installed in the installed part. And replacing the secondary sealing device with another secondary sealing device.

ADVANTAGE OF THE INVENTION According to this invention, the internal pump which can perform the inspection of a secondary seal apparatus easily by a simple and compact structure, and its inspection method can be provided, without removing an impeller and an impeller shaft.
Moreover, it becomes possible to set the inspection period of apparatuses, such as an impeller shaft, without being influenced by the inspection period of a secondary sealing apparatus.

It is a longitudinal section showing the structure of the internal pump concerning one embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view in the vicinity of a secondary seal device shown in FIG. 1. It is the schematic which shows the mode at the time of the inspection in the state in which the 1st secondary seal apparatus from the top is installed in the to-be-installed part of the internal pump. It is the schematic which shows a mode that another secondary seal apparatus is added and installed below the secondary seal apparatus installed in the to-be-installed part. It is the schematic which shows the mode at the time of the inspection in the state in which the secondary sealing apparatus of the 1st from the top and the secondary sealing apparatus of the 2nd (lowermost) from the top are installed in the to-be-installed part of an internal pump. .

Embodiments of the present invention will be described in detail with reference to the drawings as appropriate.
Note that, in the drawings shown below, the same members or corresponding members are denoted by the same reference numerals, and redundant description is omitted as appropriate. In addition, the size and shape of the member may be schematically represented by being modified or exaggerated for convenience of explanation.

An internal pump 100 according to an embodiment of the present invention will be described with reference to FIGS.
FIG. 1 is a longitudinal sectional view showing a structure of an internal pump 100 according to an embodiment of the present invention. FIG. 2 is an enlarged cross-sectional view of the vicinity of the secondary seal device 7 shown in FIG.

  As shown in FIG. 1, an internal pump 100 according to an embodiment of the present invention circulates a reactor coolant (reactor water) in a reactor pressure vessel 1 of an improved boiling water reactor (ABWR). Therefore, a plurality of units are installed at the bottom of the reactor pressure vessel 1.

  The internal pump 100 includes an impeller 3 disposed at a lower portion in the reactor pressure vessel 1, an impeller shaft 4 for mounting an impeller 3 on the upper end side, and an underwater motor 10 for driving the impeller 3 on the lower end side, A motor casing (casing) 2 that extends downward from the bottom of the reactor pressure vessel 1 and houses the submersible motor 10 and the impeller shaft 4 and a motor cover 13 that seals the bottom of the motor casing 2 are provided. Yes.

  The submersible motor 10 includes a motor rotor 8 and a motor stator 9. The motor rotor 8 is arranged on the outer peripheral side of the impeller shaft 4 by moving and mounting the submersible motor 10 from below the impeller shaft 4 to the axial direction (hereinafter simply referred to as “axial direction”) of the impeller shaft 4. The impeller shaft 4 is connected by a key or the like so as to be able to transmit a rotational force.

  The internal pump 100 includes a diffuser 5 that is a stationary hydraulic part of the internal pump 100 and a stretch tube that fixes the diffuser 5 to the upper surface of a boss portion 22 that protrudes upward from the inner surface of the reactor pressure vessel 1. 6 is provided. The stretch tube 6 is inserted into the neck portion of the motor casing 2, and the lower end thereof is fastened and fixed by a stretch tube nut 23.

  A thrust collar 11 is fixed to the lower end of the impeller shaft 4, and the thrust collar 11 is supported in the axial direction by a bearing 12. The motor cover 13 is fastened and fixed to the lower end of the motor casing 2 by a screw member.

  A secondary seal device 7 that seals or separates the impeller shaft 4 and the motor casing 2 is provided in the motor casing 2. And in the motor casing 2, the to-be-installed part 19 which can install the secondary seal apparatus 7 in multiple numbers (here two) is formed.

  As shown in FIG. 2, the installed portion 19 includes a first set position 24 where one secondary seal device 7 can be installed, and the secondary seal device 7 below the first set position 24 in the axial direction. And a second set position 25 that can be installed. The secondary sealing device 7 is detachably held on the inner wall of the motor casing 2 by holding means such as a retaining ring.

  FIG. 2 shows a state in which the secondary sealing device 7A is installed at the first set position 24 and the secondary sealing device 7B is installed at the second set position 25. Here, the secondary sealing device 7 is a general term for the secondary sealing device 7A and the secondary sealing device 7B.

  The secondary sealing device 7 includes a packing box 15 as a box and a rubber seal member 16 installed in the packing box 15. The motor casing 2 is provided with a plurality of nozzles 14 for injecting pressurized water for operating the plurality of secondary seal devices 7 respectively. In other words, the plurality of nozzles 14 can reliably and independently deliver pressurized water to the first set position 24 and the second set position 25, respectively.

  By injecting pressurized water into the packing box 15 from a nozzle 14 connected to an external water injection system (not shown), the inside of the packing box 15 is pressurized, the seal member 16 is elastically deformed, and the outer peripheral surface of the impeller shaft 4 Close contact with. In this manner, the reactor water is prevented from leaking outside.

  An opening / closing valve 20 is provided in each of the plurality of pipes 21 connected to the plurality of nozzles 14. Which nozzle among the plurality of nozzles 14 to be used for water injection to the secondary seal device 7 by manually or automatically operating the open / close valve 20 installed in the pipe 21 branched from the external water injection system Selection is possible. That is, both of the plurality of secondary seal devices 7 can be operated, or either one can be selectively operated.

Next, an inspection method of the internal pump 100 configured as described above will be described with reference to FIGS.
FIG. 3 is a schematic view showing a state at the time of inspection in a state where the first secondary seal device 7A from the top is installed in the installation portion 19 of the internal pump 100. FIG. FIG. 4 is a schematic view showing a state in which another secondary seal device 7B is additionally installed below the secondary seal device 7A installed in the portion 19 to be installed. FIG. 5 shows an inspection in a state where the first secondary sealing device 7A from the top and the second (lowermost) secondary sealing device 7B from the top are installed on the installation portion 19 of the internal pump 100. It is the schematic which shows the mode of.

  In the previous stage, the first secondary seal device 7A from the top is installed in the installation portion 19 of the internal pump 100. Then, the internal pump 100 is operated by rotating the impeller 3 by the submersible motor 10 in a state where the secondary seal device 7A is not operated, that is, in a state where pressurized water is not injected into the secondary seal device 7A. In this state, when the inspection is performed by removing the motor cover 13 and the submersible motor 10 (see FIG. 1), the secondary seal device 7A installed in the installation portion 19 is operated as shown in FIG. Seal the water. Then, the water in the motor casing 2 is drained, and then the motor cover 13 and the submersible motor 10 are removed.

  In the installed state, the impeller 3 and the impeller shaft 4 are supported by a bearing 12 via a thrust collar 11 (see FIG. 1). However, when the submersible motor 10 is taken out, the thrust collar 11 is removed from the rotating body such as the impeller shaft 4, so that the bearing 12 is not supported, and the impeller 3 and the impeller shaft 4 are lowered downward. The lower surface of the flange rests on the upper end of the stretch tube 6 (see FIG. 1). At this time, a primary seal that prevents external leakage of the reactor water is formed by the metal surface contact. However, since the primary seal is a seal only by metal surface contact, it does not form a complete seal due to adhesion of a clad or the like in use, and it is necessary to use it together with the secondary seal device 7.

  Before the sealing member 16 (see FIG. 2) of the first secondary sealing device 7A installed in the installation portion 19 deteriorates, the secondary sealing device 7 is inspected. In the inspection of the secondary sealing device 7, as shown in FIG. 4, the secondary sealing device 7A installed in the installation portion 19 is operated to seal the reactor water. In this state, the water in the motor casing 2 is drained, and then the motor cover 13 and the submersible motor 10 are removed, and the secondary installed in the installation part 19 without removing the impeller 3 and the impeller shaft 4. Another secondary sealing device 7B is additionally installed below the sealing device 7A.

  Alternatively, in the previous stage, the first secondary sealing device 7A from the top and the second (lowermost) secondary sealing device 7B from the top may be installed in the installation portion 19 of the internal pump 100. . In this case, in the inspection of the secondary sealing device 7, the water in the motor casing 2 is drained in a state where the secondary sealing device 7A is operated and the reactor water is sealed, and then the motor cover 13 and the submersible motor 10 are discharged. And the lowermost secondary seal device 7B among the secondary seal devices 7A and the secondary seal devices 7B installed in the installed portion 19 is replaced with another secondary seal device.

  That is, in the present embodiment, at least one secondary seal device 7 is installed in the installation part 19 of the internal pump 100 so that the internal pump 100 is operated. Another secondary seal device is added and installed below the secondary seal device 7 installed at 19. Alternatively, the lowermost secondary sealing device 7 among a plurality of devices installed in the installation target 19 is replaced with another secondary sealing device.

  In addition, in the state where another secondary sealing device 7B is added later below the secondary sealing device 7A, or the lowermost secondary sealing device 7B is replaced with another secondary sealing device, the motor cover 13 When the inspection is performed with the submersible motor 10 removed, the secondary sealing device 7B installed by addition or replacement as shown in FIG. 5 is operated to seal the reactor water. Then, the water in the motor casing 2 is drained, and then the motor cover 13 and the submersible motor 10 are removed.

  It should be noted that the second secondary sealing device 7A from the top installed in the portion to be installed 19 may be operated simultaneously with the operation of the secondary sealing device 7B installed by addition or replacement. In this case, the opening / closing valve 20 provided in the pipe 21 connected to the first secondary seal device 7A can be omitted.

  In addition, the inspection of the secondary seal device 7 performed before the seal member 16 (see FIG. 2) of the secondary seal device 7B installed additionally or replaced is deteriorated in accordance with the inspection cycle of the impeller 3 and the impeller shaft 4. Can be implemented. In this case, first, the secondary seal device 7 is operated to drain the water in the motor casing 2, the motor cover 13 is removed, the submersible motor 10 is taken out, and then the lower end of the motor casing 2 is closed with a closing plate (not shown). To close. After that, after the operation of the secondary seal device 7 is canceled, the impeller 3 and the impeller shaft 4 are extracted upward, the opening of the diffuser 5 is closed by a closing plug (not shown), and enters the motor casing 2. Drain the reactor water again. Then, after removing the closing plate at the lower end of the motor casing 2, it is possible to replace all of the plurality of secondary seal devices 7 installed in the installation target 19.

As described above, according to the present embodiment, the installation portion 19 in which a plurality of secondary seal devices 7 can be installed is formed in the motor casing 2, so that the impeller 3 and the impeller shaft 4 can be removed without removing the impeller 3 and the impeller shaft 4. It is possible to provide the internal pump 100 and its inspection method that can easily inspect the next sealing device 7 with a simple and compact configuration.
In addition, it is possible to set the inspection cycle of equipment such as the impeller shaft 4 without being influenced by the inspection cycle of the secondary seal device 7. Therefore, there is no need to inspect the equipment including the work of removing the impeller shaft 4 and the like that requires a large number of work steps in accordance with the inspection cycle of the secondary seal device 7 that is shorter than the inspection cycle of the equipment such as the impeller shaft 4. As a result, the operating rate of the nuclear reactor can be improved.

  As mentioned above, although this invention was demonstrated based on embodiment, this invention is not limited to above-described embodiment, Various modifications are included. For example, the above-described embodiment has been described in detail for easy understanding of the present invention, and is not necessarily limited to one having all the configurations described. It is possible to add, delete, and replace other configurations for a part of the configuration of the above-described embodiment.

  For example, in the above-described embodiment, the installation portion 19 in which two secondary sealing devices 7 can be installed is formed in the motor casing 2, but the installation in which three or more secondary sealing devices 7 can be installed is provided. A part may be formed.

1 Reactor pressure vessel 2 Motor casing (casing)
DESCRIPTION OF SYMBOLS 3 Impeller 4 Impeller shaft 5 Diffuser 6 Stretch tube 7 (7A, 7B) Secondary seal device 8 Motor rotor 9 Motor stator 10 Submersible motor 11 Thrust collar 12 Bearing 13 Motor cover 14 Nozzle 15 Packing box 16 Seal member 19 Installation part 20 Opening and closing Valve 21 Piping 22 Boss portion 23 Stretch tube nut 24 First set position 25 Second set position 100 Internal pump

Claims (4)

An impeller shaft mounted on the lower end side of an underwater motor for mounting the impeller disposed on the lower end in the reactor pressure vessel on the upper end side and driving the impeller;
A casing that extends downward from the bottom of the reactor pressure vessel and houses the submersible motor and the impeller shaft;
A secondary seal device provided in the casing and sealing or separating the impeller shaft and the casing; and
An internal pump characterized in that a plurality of installation portions in which a plurality of the secondary seal devices operated by pressurized water can be installed in the axial direction of the impeller shaft are formed in the casing.   2. The internal pump according to claim 1, wherein the casing is provided with a plurality of nozzles for injecting pressurized water for operating the plurality of secondary seal devices.   The internal pump according to claim 2, wherein an opening / closing valve is provided in each of the plurality of pipes respectively connected to the plurality of nozzles. At least one of the secondary seal devices is installed in the installation portion of the internal pump according to any one of claims 1 to 3, and the internal pump is operated.
At the time of inspection of the internal pump, another secondary seal device is additionally installed below the secondary seal device installed in the installed part, or a plurality of installed in the installed part An inspection method for an internal pump, wherein the lowermost secondary sealing device is replaced with another secondary sealing device.

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