JPH0531956B2 - - Google Patents

Description

Detailed Description of the Invention [Technical Field of the Invention] The present invention relates to an improved boiling water reactor (A-
This invention relates to an internal pump motor handling device for attaching and detaching the internal pump motor in BWR).

[Technical background of the invention]

Generally, in a boiling water reactor (hereinafter referred to as BWR), coolant is regenerated by forced circulation between a recirculation pump installed outside the reactor pressure vessel and a jet pump inside the reactor pressure vessel. However, 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. If something like this happens, 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.
FIG. 2 shows a schematic configuration of the A-BWR, in which reference numeral 1 is a reactor pressure vessel 1, and a reactor core 2 consisting of a plurality of fuel assemblies (not shown) is housed in a cylindrical shroud 3. ing. A water supply spargeer 5 connected to a water supply pipe 4 is provided above the reactor core 2.
Further above, a steam separator 6 and a steam dryer 7 are provided. Reference numeral 8 denotes a main steam pipe for extracting steam generated within the reactor pressure vessel 1;
1 is a control rod drive mechanism for inserting a control rod 10 into the reactor core 2 from below and pulling it out to control the output of the reactor.

Further, reference numeral 11 indicates the lower mirror portion 1a of the reactor pressure vessel 1.
multiple internal pumps installed in the These internal pumps 11 are composed of a pump section 12 and a motor section 13, as shown in FIG. The pump section 12 is an impeller 1
4, a differential user 15, a differential user wear ring 16, etc., and an impeller shaft 17 is fixed to the impeller 14. The impeller shaft 17 hangs down to the motor section 13 and is connected to the motor section 13. The diff user 15 is fixed by a stretch tube 19 to the upper part of a nozzle 18 protruding from the bottom of the reactor pressure vessel 1.
is fixed by a stretch tube nut 20. In addition, stretch tube nuts 20
A secondary seal 21 is provided at the bottom of the .

The motor section 13 is constructed by housing a rotor 22, a stator 23, etc. in a motor casing 24, and the tip of the motor section 13 is inserted into a nozzle 18 and welded to the lower mirror section 1a of the reactor pressure vessel 1. The pump casing 25 is housed inside a pump casing 25 that protrudes downward. Furthermore, cooling water is circulated within the pump casing 25 through a circulation pipe 26 to prevent the motor section 13 from burning out.

A stud bolt 27 is connected to the lower end of the impeller shaft 17.
A nut 28 is screwed onto the lower end of the impeller shaft 17 to connect the impeller shaft 17 and the rotor 22 of the motor section 13. The motor section 13 also has a main flange 2 that closes the lower end opening of the pump casing 25.
9, and in this state, the lower end 17 of the collar of the impeller shaft 17
A distance c of about 10 mm is provided between a and the upper end 19a of the stretch tube 19. A circular hole is provided in the center of the main flange 29, and this circular hole is closed by a small flange 30. By removing this small flange 30, the nut 28 can be attached and removed through the circular hole.
Note that the nut 28 and main flange 29 are removed, and the motor section 13 is attached to the pump casing 25.
When pulled out from the inside, the impeller shaft 17 and the impeller 14 descend under their own weight, eliminating the gap between the lower end 17a of the collar of the impeller shaft 17 and the upper end 19a of the stretch tube 19. The outflow of reactor water is now being prevented.

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

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 remove the internal pump 11, first stop the reactor, fill the reactor pressure vessel 1 with water, shield it from radiation, remove the reactor pressure vessel cover, and then fill the reactor pressure vessel 1 with water. After the steam dryer 7, steam separator 6, shroud head, etc. are removed, each component is removed from the top and bottom of the reactor pressure vessel 1. The same applies to the installation work.

That is, the pump section 1 of the internal pump 11
The removal and installation operations 2 are performed from above the reactor pressure vessel 1, and the removal and installation operations of the motor section 13 are performed from below.

Among these, the work for attaching the motor section 13, which is related to the present invention, is performed after the other components are attached. That is, this is done after the differential user 15, differential user wear ring 16, stretch tube 19, impeller 14, and impeller shaft 17 are attached from above, and the stretch tube nut 20 and secondary seal 21 are attached from below. Water leakage prevention at this stage is two-fold. First, since the impeller 14 and the impeller shaft 17 are not pushed up by the motor section 13, the lower end 17a of the collar of the impeller shaft 17 descends until it touches the upper end 19a of the stretch tube 19, and is strongly pressed by its own weight and water head pressure to form a seal. . Furthermore, the secondary seal 21 is activated to seal between the pump casing 25 and the impeller shaft 17, thereby backing up. In this state, the motor section 13 is pushed up from below together with the main flange 29, inserted into the pump casing 25, and raised to just before supporting the impeller shaft 17.

After that, replace the small flange 30 with the main flange 2.
9, fill the pump casing 25 with water, release the secondary seal 21, and remove the motor part 1.
3 together with the impeller shaft 17.
Thereafter, the secondary seal 21 is activated to drain the water inside the pump casing 25, the small flange 30 is removed, and the nut 28 is tightened on the stud bolt 27.

[Problems with background technology]

This double measure against water leakage is taken when the motor section 13 is raised alone, but the impeller shaft 17 is inserted into the center of the motor section 13 when the motor section 13 is raised. If contact occurs between the motor section 13 and the impeller shaft 17 and the impeller shaft 17 is lifted as the motor section 13 rises, there is a possibility of water leakage. That is, when the impeller shaft 17 is lifted, it is natural that a space will be created between the lower end 17a of the collar of the impeller shaft 17 and the upper end 19a of the stretch tube, causing water leakage, but the secondary seal 21 is also a static seal. Therefore, if the impeller shaft 17 was moving, there was a possibility that sufficient sealing could not always be achieved.

[Purpose of the invention]

The present invention was made based on the above circumstances, and an object thereof is to provide an internal pump that can reliably prevent water leakage when installing the motor section 13 of the internal pump 11 and ensure work safety. An object of the present invention is to provide a pump motor handling device.

[Summary of the invention]

In order to achieve the above object, the internal pump motor handling device according to the present invention includes a handling device base installed below the pump casing, and a handling device base installed upward from the base, which a plurality of guide screws whose upper ends are rotatably supported at the lower part; a rotation drive device installed on the base for rotationally driving the guide screws; and a main flange that closes the lower end opening of the pump casing. a plurality of lifting nuts that are attached to a peripheral edge and move up and down as the guide screw rotates; and a tension bar that has a threaded portion at its upper end that engages with a stud bolt that projects from the lower end of the impeller shaft of the internal pump. , a turnbuckle whose lower end is connected to the center of the upper surface of the base and applies downward tension to the stud bolt via the tension bar; a rotating handle for adjusting the length of the turnbuckle; It is equipped with a load cell that detects the tension of the load cell.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 shows the state in which the motor section 13 of the internal pump 11 is installed in the pump casing 25 by the motor section handling device 41. The configuration of the motor section handling device 41 is as follows.

That is, reference numeral 42 is a handling device base, and a rotation drive device 43 is installed on this base 42. Further, reference numerals 44 and 44 denote a pair of guide screws which are configured to rotate in conjunction with each other via a chain or the like and are simultaneously rotationally driven by the rotary drive device 43. Each guide screw 44 includes:
Lifting nuts 45, 45 attached to the outer periphery of the main flange 29 are screwed together, respectively. Reference numerals 46 and 46 denote a pair of brackets installed at symmetrical positions on the lower outer circumference of the pump casing 25 of the internal pump 11.
The upper end of the guide screw 44 is rotatably supported inside the guide screw 44.
A bearing 47 that prohibits vertical movement is incorporated.

Further, a tension bar 50 is connected to the center of the handling device base 42 via a load cell 48 and a turnbuckle 49 as a tension applying mechanism. Note that reference numeral 51 is a handle for rotating the turnbuckle 49. Tension bar 5 above
0 extends upward through a circular hole at the center of the main flange 29, and a threaded portion 52 is provided at the upper end thereof. This threaded portion 52 is threadedly engaged with a threaded portion provided at the lower end of the stud bolt 27 to connect the tension bar 50 and the impeller shaft 17.

Therefore, after maintenance and inspection of the internal pump 11, the motor section 13 is removed by the motor section handling device 41.
To carry out the installation work, first, the motor section 13 from which the small flange 30 at the center of the main flange 29 has been removed is attached to the motor section handling device 41 and raised to an intermediate position. That is, the bracket 46 is attached to the lower part of the outer periphery of the pump casing 25, and the lifting nut 45 is attached to the outer periphery of the main flange 29. Raise the motor section 13 and position the motor section 13 so that the turnbuckle 49 and handle 51, which will be attached later, are under the motor section 13. Next, the tension bar 50 is passed through the hollow part of the motor part 13, the load cell 48, the turnbuckle 49 and the handle 51 are assembled, and the threaded part 52 is threadedly connected to the lower end of the stud bolt 27. Appropriate downward tension is applied to the impeller shaft 17. The strength of the tension at this time can be detected by the load cell 48. And again the rotary drive device 4
3, the motor section 13 is raised and inserted into the pump casing. The ascent continues until just before the motor section 13 supports the impeller shaft 17.
During the rise up to this point, downward tension is acting on the impeller shaft 17, so the impeller shaft 1
7 collar lower end 17a and stretch tube 19
Since there is no gap between the upper end 19a and the upper end 19a, water leakage is prevented. Moreover, since overload can be detected by the load cell 48 at the stage when some kind of contact occurs between the motor section 13 and the impeller shaft 17,
The rise can then be stopped.

Furthermore, the final pump casing 2 of the motor section 13
5 is installed by removing the tension bar 50, but there is no risk of water leakage during this operation.

As described above, since the installation work of the motor part 13 is performed with downward tension applied to the impeller shaft 17, the motor part 13 is
The impeller shaft 17 and the impeller 14 are not pushed up as the impeller shaft 17 and the impeller 14 rise. Therefore, it is possible to maintain a sealed state between the lower end 17a of the collar of the impeller shaft 17 and the upper end 19a of the stretch tube 19, to reliably prevent water leakage from this gap, and to ensure safety in work. I can do it.

〔Effect of the invention〕

As described above in detail, according to the internal pump motor handling device according to the present invention, water leakage can be reliably prevented when the motor is installed, and work safety can be ensured. Furthermore, according to the present invention, the tension can be easily adjusted by adjusting the length of the turnbuckle using the rotation handle. In addition, by detecting the downward tension acting on the stud bolt with a load cell, it is possible to detect when the motor comes into contact with a tension bar, etc. during lifting and lowering, and the lifting and lowering of the motor stops when the motor comes into contact with the tension bar, etc. can be done.

[Brief explanation of the drawing]

FIG. 1 is a front view of a motor handling device showing an embodiment of the present invention, FIG. 2 is a longitudinal sectional view showing the schematic structure of an A-BWR, and FIG. 3 is a longitudinal sectional view of an internal pump. DESCRIPTION OF SYMBOLS 1... Reactor pressure vessel, 1a... Lower mirror part, 11... Internal pump, 13... Motor part, 14... Impeller, 15... Defuser, 17... Impeller shaft, 17a... Collar lower end of impeller shaft,
19a...Stretch tube upper end, 22...Rotor, 25...Pump casing, 27...Stud bolt, 29...Main flange, 41...Motor section handling device, 42...Handling device base, 43...Rotary drive device, 44...Guide screw U, 45... Lifting nut, 46... Bracket, 47... Bearing, 48... Load cell, 49... Turnbuckle (tension adding mechanism),
50...Tension bar, 51...Operation handle.

Claims (1)

[Claims] 1. A motor section is housed in a pump casing that protrudes downward from the lower mirror section of the reactor pressure vessel, an impeller and a diffuser are provided around the core inside the reactor pressure vessel, and an impeller fixed to the impeller. The shaft is suspended down to the motor section, a stud bolt connected to the lower end of the impeller shaft is connected to the rotor of the motor section, the differential user is fixed to the lower mirror section of the reactor pressure vessel by a stretch tube, and the pump casing is fixed to the lower mirror section of the reactor pressure vessel. The motor section is held at a constant height by a main flange that closes the lower end opening of the impeller shaft, and a constant distance is provided between the lower end of the collar of the impeller shaft and the upper end of the stretch tube. The device for attaching and detaching the motor section of an internal pump includes a handling device base installed below the pump casing, and a handling device base extending upward from the base and rotating an upper end to the bottom of the pump casing. a plurality of freely supported guide screws; a rotary drive device installed on the base for rotationally driving the guide screws; and a rotation drive device attached to the peripheral edge of the main flange that moves up and down by rotation of the guide screws. a plurality of lifting nuts, a tension bar having a threaded portion at its upper end that is screwed into the stud bolt, and a turnbuckle whose lower end is connected to the center of the upper surface of the base and applies downward tension to the stud bolt via the tension bar. A motor handling device for an internal pump, comprising: a rotation handle for adjusting the length of the turnbuckle; and a load cell for detecting downward tension acting on the stud bolt.