JPH0531957B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a pump section housing rack for an internal pump that accommodates a pump section of an internal pump removed from a boiling water nuclear reactor.

[Technical Background of the Invention] Generally, in a boiling water reactor (hereinafter referred to as BWR), coolant is forced between a recirculation pump installed outside the reactor pressure vessel and a jet pump inside the reactor pressure vessel. The coolant is recirculated by circulating the coolant, but such a recirculation system has a complicated structure, and the recirculation piping that connects the reactor pressure vessel and the recirculation pump becomes a boundary for the coolant. Therefore, if this pipe should break, there is a possibility of loss of coolant.

Therefore, we developed a BWR equipped with an internal pump that forcedly circulates coolant directly within the reactor pressure vessel.
(hereinafter referred to as A-BWR) has been developed.
As shown in FIG. 1, this A-BWR has a reactor core 2 consisting of a plurality of fuel assemblies (not shown) formed within a reactor pressure vessel 1, and a cylindrical shroud 3.
is housed within. Above the reactor core 2 is a water supply pipe 4.
A water supply spargeer 5 connected to the
Further above, a steam separator 6 and a steam dryer 7 are provided. In the figure, 8 is the main steam pipe for taking out the steam generated in the reactor pressure vessel 1, and 9
is a control rod drive mechanism for inserting the control rods 10 into the reactor core 2 and controlling the output of the nuclear reactor.

Further, reference numeral 11 denotes a plurality of internal pumps attached to the opaque part of the reactor pressure vessel 1. These internal pumps 11 are composed of a pump section 12 and a motor section 13, as shown in FIG. The pump section 12 includes an impeller 14, a differential user 15, and a differential user wear ring 1.
The impeller 14 is connected to the motor section 13 via a drive shaft 17. The diff user 15 has a stretch tube 19 attached to the top of a nozzle 18 protruding from the bottom of the reactor pressure vessel 1.
Stretch tube 1
9 is fixed by a stretch tube nut 20. In addition, Stretch Tube Nut 2
A secondary seal 21 is provided at the bottom of 0.

The motor section 13 is constructed by housing a rotor 22, a stator 23, etc. in a motor casing 24, and the motor section 13 has a pump casing 25 whose tip is inserted into a nozzle 18 and welded to the reactor pressure vessel 1. is housed within. and,
Cooling water is circulated within the pump casing 25 through a circulation pipe 26 to prevent the motor section 13 from burning out.

A having such an internal pump 11
- Since the BWR does not have a recirculation pump outside the reactor pressure vessel 1 unlike the conventional external recirculation type BWR, it does not require recirculation piping. For this reason,
The installation space for recirculation equipment within the primary containment vessel can be significantly reduced, and the capacity of the emergency core cooling system can also be reduced. Furthermore, since the motor section 13 of the internal pump 11 is housed in the pump casing 25 with excellent watertightness, there is no need for a sliding shaft sealing device, and the structure is simple and reliable with less possibility of reactor water leakage. Excellent in sex.

By the way, A-
With the adoption of BWR, it is necessary to periodically perform maintenance and inspection work on the internal pump 11. To inspect the internal pump 11, first stop the operation of the reactor, fill the reactor pressure vessel 1 with water,
After shielding from radiation, the reactor pressure vessel lid is removed, the reactor well is filled with water, and the steam dryer 7, steam/water separator 6, shroud head, etc. are removed. After that, the internal pump 11 is removed from the reactor pressure vessel 1. The removal work of the internal pump 11 is performed from above and below the reactor pressure vessel 1, and the work procedure is as follows.

First, the secondary seal 21 seals between the pump casing 25 and the drive shaft 17 to shut off the reactor water in the reactor pressure vessel 1, and then drains the water in the pump casing 25. Thereafter, the motor section 13 is removed from below the pump casing 25. Next, after attaching a closing flange to the lower end of the pump casing 25, the interior of the pump casing 25 is filled with make-up water, and then the secondary seal 21 is released. In this state, the impeller 14 and the drive shaft 17 are removed from above the reactor pressure vessel 1. Next, the opening of the diffuser 15 is closed from above the reactor pressure vessel 1 with an upper closing plate, and the water in the pump casing 25 is discharged. In this state, remove the closing flange from below the pump casing 25, and
Remove the secondary seal 21 and stretch tube nut 20 from inside. After attaching the closing flange to the lower end of the pump casing 25 again, it is filled with makeup water. In this state, the upper closing plate, the differential user 15, the differential user wear ring 16, and the stretch tube 19 are removed from the upper side of the reactor pressure vessel 1.

For installation after inspection and maintenance, perform the above procedure in reverse order.

[Problems with the Background Art] However, during maintenance and inspection of the internal pump 11, the installation position, especially the installation and removal work of each component of the pump section 12, is at a depth of more than 20 meters below the water surface from above the reactor. Therefore, it is difficult. For this reason, grips for attaching and detaching each component of the pump section 12 have been devised.

On the other hand, the pump components removed from the inside of the reactor pressure vessel 1, such as the impeller 14 and the drive shaft 17, which were removed together, were simply temporarily placed in a random manner in a fuel storage pool or the like.

Therefore, these pump components occupy a large space within the fuel storage pool, and there is a possibility that the storage space for storing spent fuel will be significantly reduced. In addition, the temporarily placed pump components are transferred to another location during maintenance and inspection, but the transfer work is expected to be difficult because it is carried out by remote control in a narrow space.

[Object of the Invention] The present invention has been made based on the above circumstances, and its purpose is to improve the pump component of an internal pump installed below the water surface in a nuclear reactor pressure vessel, especially the impeller and drive shaft. An object of the present invention is to provide a housing rack for a pump part of an internal pump, which can be temporarily placed in an orderly manner in a fuel storage pool, and can be easily transported for maintenance and inspection.

[Summary of the Invention] In order to achieve the above object, the pump housing rack for the internal pump according to the present invention includes an annular seat plate through which the drive shaft of the internal pump is inserted from above and on which the impeller of the internal pump is seated. an annular upper plate provided at a height corresponding to the upper end of the differential user of the internal pump with reference to the upper surface of the annular seat plate and having a center hole large enough to allow the impeller to be inserted; and a plurality of simulated guide pins erected to simulate the guide pins of the internal pump.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to FIGS. 3 to 5.

The pump housing rack 31 has four support plates 33 erected on an annular bottom plate 32.
An annular top plate 34 is fixed thereon, and an annular bottom plate 32 is fixed thereon.
An annular seat plate 35 is fixed to four support plates 33 at a position between the annular upper plate 34 and the annular upper plate 34 . A hanging fitting 36 is attached to the upper surface of the annular bottom plate 32. Also, the annular bottom plate 32 and the annular seat plate 3
Each of the center holes 32a, 35a of No. 5 is sized to allow the drive shaft 17 of the internal pump 11 to be inserted therethrough from above. The center hole 34a of the annular upper plate 34 is sized to allow the impeller 14 to be inserted therein. As shown in FIG. 5, the impeller 14 can be seated on the upper surface of the annular seat plate 35. Further, the annular upper plate 34
The impeller 14 is attached to the annular seat plate 35 as shown in FIG.
When seated on the upper surface, the position corresponds to the upper end of the differential user well ring 16 with respect to the impeller 14 (a height position corresponding to the upper end of the differential user 15 with the upper surface of the annular seat plate 35 as a reference), and this annular upper A plurality of simulated guide pins 3 are provided on the upper surface of the plate 34.
7 is provided protrudingly. The simulated guide pin 37 is a guide pin 15 at the upper end of the differential user 15 with the impeller 14 as a reference when the impeller 14 is seated on the annular seat plate 35 as shown in FIG.
It is located at a position corresponding to a (see Figure 2). In addition,
The guide pin 15a is used for mounting the impeller 14,
This is provided for positioning the impeller-specific grip used for removal.

That is, reference numeral 38 in FIG. 5 indicates a grip exclusively for the impeller, and this grip 38 abuts against the upper end of the differential user wear ring 16 in FIG. Positioning in the horizontal direction is performed by engaging with a plurality of guide pins 15a provided at the upper end. This impeller-specific grip 38 is provided with a mechanism for gripping and releasing the impeller bolt portion 14a at the upper end of the impeller 14.

In FIG. 5, the impeller-specific grip 38
The grip 38 is shown positioned in the pump housing rack 31, and the grip 38 is brought into contact with the upper surface of the annular upper plate 34 for vertical positioning, and is engaged with the dummy guide pin 37 for horizontal positioning. will be done.

The pump housing rack 31 of the internal pump constructed as described above is installed, for example, in a fuel storage pool.

At the time of maintenance and inspection of the internal pump 11, the impeller 14 and drive shaft 17 are taken out together from inside the reactor pressure vessel 1 using the impeller-dedicated grip 38, and the pump part installed in the fuel storage pool is housed. It is supported on a rack 31 as shown in FIG. The impeller-specific grip 38 is placed on the annular upper plate 34 and the dummy guide pin 37 is placed on the annular upper plate 34.
The impeller 14 is released from the grip in the positioned state, whereby the impeller 14 and the drive shaft 17 are held within the pump housing rack 31. Further, by performing the reverse procedure, the impeller 14 and the drive shaft 17 can be taken out from the pump housing rack 31 using the impeller-dedicated grip 38. The impeller 14 and drive shaft 17 taken out from the storage rack 31 are introduced into the reactor pressure vessel 1, and the grip 38 abuts the upper end of the differential user wear ring 16 and is positioned on the guide pin 15a. , is incorporated into the differential user 15 at an appropriate position. The impeller 14 and the drive shaft 17 are held at the appropriate positions as the gripping tool 38 releases the impeller 14.

Furthermore, when performing maintenance and inspection of the impeller 14 and drive shaft 17 housed in the pump housing rack 31, the housing rack 31 can be transported to a predetermined maintenance and inspection facility by lifting the hanging fittings 36 together. Such a transfer can also be carried out easily.

[Effects of the Invention] As described in detail above, according to the pump housing rack for an internal pump of the present invention, the impeller and drive shaft, which are the pump component components of the internal pump, can be temporarily and orderly placed in the fuel storage pool. It is also possible to easily carry out transportation work for maintenance and inspection. Further, according to the present invention, an annular upper plate having a center hole large enough to allow the impeller to be inserted is provided at a height corresponding to the upper end of the differential user with reference to the upper surface of the annular seat plate on which the impeller is seated. Since a plurality of simulated guide pins simulating the guide pins of an internal pump are erected at predetermined positions on the upper surface of the plate, the impeller can be easily gripped by the gripper.

[Brief explanation of the drawing]

Figure 1 is a schematic vertical cross-sectional view of a boiling water reactor;
The figure is a schematic vertical sectional view of an internal pump, and FIGS. 3 to 5 show an embodiment of the present invention.
Figure 3 is a plan view of the pump housing rack, Figure 4 is a side view of the pump housing rack, and Figure 5 shows the impeller and drive shaft inserted into the pump housing rack using special grips. FIG. 1... Reactor pressure vessel, 11... Internal pump, 12... Pump section, 13... Motor section,
14... impeller, 15... differential user, 15
a... Guide pin, 17... Drive shaft, 31... Pump housing rack, 32... Annular bottom plate, 33...
Support plate, 34... annular upper plate, 35... annular seat plate,
36... Hanging fixture, 37... Simulated guide pin, 38
...Grasp for impeller.

Claims (1)

[Claims] 1. An annular seat plate through which the drive shaft of the internal pump is inserted from above and on which the impeller of the internal pump is seated, and an annular seat plate at a height corresponding to the upper end of the differential user of the internal pump with respect to the upper surface of this annular seat plate. an annular upper plate having a central hole large enough to allow the impeller to be inserted therethrough; and a plurality of dummy guide pins erected on the upper surface of the annular upper plate to simulate guide pins of the internal pump. A pump housing rack for internal pumps featuring: