JPH08105993A - Internal pump upper plug device - Google Patents

Abstract

PURPOSE: To provide an internal pump upper plug device free from being afloat even under exposure to the systematic water pressure of a feedwater system. CONSTITUTION: This device has such a cylindrical upper half as forming the major section of the body of an internal pump upper plug 31, a projection 34 formed on the upper half, and such a cylindrical lower half as communicated to the upper half, having a smaller diameter than the upper half and extended down from the lower end thereof. In addition, the device is equipped with a diffuser 13 having a cutout section 35 concentrically enveloping the impeller 12 of an internal pump 4 and formed vertically for the insertion of the projection 34, as well as a groove section 32 peripherally formed so as to be communicated to the section 35.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an upper plug device for an internal pump incorporated in a boiling water reactor, and particularly to prevent floating when pouring water into a motor casing during disassembly and reassembly of the internal pump. The present invention relates to an internal pump upper plug device suitable for

[0002]

2. Description of the Related Art Generally, at the time of periodic inspection in a boiling water reactor, the upper lid of the reactor pressure vessel is removed and water is filled in the reactor pressure vessel and in the reactor well above the core of the reactor pressure vessel. This water filling is for shielding the radiation from the fuel and the reactor pressure vessel constituting the core, and the fuel exchange and the like are also performed underwater to shield the radiation.

By the way, the reactor pressure vessel is provided with nozzles for connecting pipes and attaching equipment. When the equipment and pipes attached to these nozzles are taken out at the time of regular inspection, the nozzles must be closed to prevent outflow of reactor water.

In FIG. 6, in the reactor pressure vessel 1,
A lower mirror 1a of the reactor pressure vessel 1 is inserted at a penetrating portion 1b below a downcomer 3 having a horizontal cross section formed in an annular shape between a core 2 and an inner peripheral surface of the reactor pressure vessel 1, and a plurality of the lower pressure chamber 1a Internal pumps 4 are equally distributed in the circumferential direction.
During normal operation, the coolant is forcedly circulated from the downcomer 3 into the core 2 by the internal pump 4.

In FIG. 7, the internal pump 4 is composed of a pump section 10 and a motor section 11. The pump portion 10 is driven by the motor portion 11 to pump shaft 15
It has an impeller 12 which is driven through the diffuser 13 and a diffuser 13 which concentrically surrounds the impeller 12. The diffuser 13 is fixed via a stretch tube 17 to the upper portion of a nozzle 16 projecting from the bottom of the reactor pressure vessel 1 and concentrically surrounding the pump shaft 15. Also,
A secondary seal 19 is mounted below the stretch tube nut 18.

The motor unit 11 includes a rotor 20 and a stator 2.
1, the tip of the motor casing 22 for accommodating them is inserted into the nozzle 16, and the reactor pressure vessel 1
It is fixed to the lower mirror 1a by welding. Reference numeral 23 in the drawing denotes a cooling water circulation pipe communicating with the motor casing 22, and 24
Is an auxiliary cover provided on the bottom plate 22a of the motor casing 22, 25 is a coupling stud nut that connects the pump shaft 15 and the motor unit 11, and 26 is a main stud nut that fixes the bottom plate of the motor casing 22. .

In the conventional internal pump 4 having the above structure, the maintenance and inspection work is performed as follows. That is, first, the motor casing 2
2 and the pump shaft 15 are sealed, the reactor water in the reactor pressure vessel 1 is shut off, and then the water in the motor casing 22 is discharged.

Next, the bottom plate 22 of the motor casing 22
The auxiliary cover 24 is taken out from a, the coupling stud nut 25 is removed, and the pump shaft 15 and the motor part 11 are separated. In this state, the main stud nut 26 is loosened, and the motor portion 11 and the pump shaft 15 are lowered about 10 mm by their own weight. Due to this lowering, the projection 15a provided inside the furnace of the pump shaft 15
Is in contact with the upper surface of the nozzle 16 to seal the reactor water.
In this state, the action of the secondary seal 19 is performed, and the inside of the motor casing 22 is completely drained. Here, the main stud nut 26 is removed and the motor unit 11 is removed.

Next, the bottom plate 22 is attached to the motor casing 22.
a, after the auxiliary cover 24 is attached, auxiliary water is filled in the motor casing 22, and the sealing by the secondary seal 19 is released here. In this state, the impeller 12 is connected to the pump shaft 1 by remote control from above the reactor pressure vessel 1.
Remove with 5.

Next, the opening of the diffuser 13 is opened from above the reactor pressure vessel 1 as shown in FIG.
It is closed by 1, and the inside of the motor casing 22 is drained.
Here, the bottom plate 22a of the motor casing 22 is removed, and the secondary seal 19 and the stretch tube nut 18 are removed from the inside of the motor casing 22. Next, after reattaching the bottom plate 22a to the motor casing 22, water is poured into the motor casing 22 from a makeup water system (hereinafter referred to as MUW), and the internal pump 4 is attached in the reverse order of the above.

[0011]

When the internal pump 4 is attached to the lower mirror 1a portion of the reactor pressure vessel 1 and the removal work is performed, the upper plug 31 is attached as described above. Further, the upper plug 31 is attached, the water in the motor casing 22 is drained, and water is injected again.

MUW is used for water injection, but the water injection pressure is about 10 Kg / cm ^2, and the upper plug 31 may float if pressure is not reduced by providing a pressure reducing valve on the upstream side.

The present invention has been made in view of the above conventional circumstances, and an object thereof is to provide an internal pump upper plug device which does not float up even when the system water pressure of the MUW is applied.

[0014]

In order to achieve the above object, an internal pump upper plug device according to claim 1 of the present invention is vertically provided by penetrating a lower mirror portion of a reactor pressure vessel. In the internal pump upper plug for closing the motor casing of the internal pump having an opening on the inner surface of the lower mirror part of the reactor pressure vessel, the cylindrical upper half part forming the main part of the internal pump upper plug body, The protrusion provided on the upper half portion, the cylindrical lower half portion including an inverted conical portion which is continuous with the upper half portion and has a diameter smaller than that of the upper half portion and which hangs down from the lower end of the upper half portion; The diffuser includes a notch portion concentrically surrounding the impeller of the pump and formed in the vertical direction for inserting the projection portion, and a groove portion communicating with the notch portion and formed in the circumferential direction. It is intended.

Further, in the internal pump upper plug device according to the second aspect of the invention, the internal pump upper plug device is vertically provided so as to penetrate through the lower mirror portion of the reactor pressure vessel, and has an opening on the inner surface of the lower mirror portion of the reactor pressure vessel. In the internal pump upper plug that closes the motor casing of the internal pump, the cylindrical upper half that forms the main part of the internal pump upper plug body and the spring that is provided in this upper half move horizontally in the horizontal direction. A fixed rod fitted into a groove provided in a circumferential direction on a diffuser that concentrically surrounds the impeller of the internal pump; and a fixed rod that penetrates through the fixed rod and the upper half portion and is vertically movable. A shaft partially having a large diameter portion for pushing the fixing rod, and an inversion which is continuous with the upper half portion and has a smaller diameter than the upper half portion and hangs down from the lower end of the upper half portion. And it has a lower half cylindrical having a conical portion.

[0016]

In the internal pump upper plug device having the above structure, the upper plug is mechanically fixed in the groove for the diffuser grip, so that it is possible to prevent the MUW from rising even if the water injection pressure is directly applied. is there.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of an internal pump upper plug device according to the present invention will be described below with reference to FIG. 1 (a) and 1 (b) are structural views showing a first embodiment of an internal pump upper plug device according to the present invention.

In FIGS. 1 (a) and 1 (b), the upper plug 31a has a height in the direction of 180 ° and a height corresponding to the depth of the diffuser gripping tool groove 32 when fitted into the diffuser 13a. A protruding portion 34 is provided. The protrusion 34 is slightly narrower than the width of the diffuser gripping groove 32 so that it can be easily fitted. Further, a sealing material 33 is provided on a portion of the lower portion of the upper plug 31a that comes into contact with the stretch tube 17.

Conventionally, the diffuser 13a has a groove 32 for a diffuser grip for installing or replacing the diffuser 13a. As shown in FIG. 2, the diffuser grip tool groove 32 is hooked with a hook 51 provided on the diffuser grip tool 50 when it is necessary to remove the diffuser 13a during an inspection such as a regular inspection as shown in FIG. It is provided to pull up.

In this embodiment, in addition to the diffuser gripping tool groove 32, two notches 35 are provided in the 180 ° direction so that the projections 34 can be inserted in the diffuser gripping tool groove 32. Mating is possible.

The protrusion 3 of the upper plug 31a of FIG. 1 (a)
The upper plug 3 (4) fits into the notch 35 of the diffuser 13a by an upper plug grip (not shown).
1a is inserted into the diffuser 13a.

Here, the upper plug 31a is rotated 90 ° so that the protrusion 34 fits into the diffuser gripping groove 32. By performing such an operation, as shown in FIG.
The state becomes as shown in the sectional view of FIG.

By performing the above operation, the upper plug 31a is mechanically fixed to the diffuser 13a. The sealing property of the upper plug 31a is ensured by the sealing material 33.

In this way, the motor casing 22
It is possible to prevent floating even when water is poured at a predetermined pressure of about 10 Kg / cm ² , which is the predetermined pressure of the MUW used when pouring water.

Next, a second embodiment of the present invention will be described with reference to FIG.
A description will be given using (a) and (b). 4 (a), (b)
In, the upper plug 31b is already in the diffuser 13. The same parts as those in FIGS. 1A and 1B are designated by the same reference numerals, and the description of the configuration will be omitted. The difference from the first embodiment is that the diffuser 13 has no notch 35 and the upper plug 31b has no protrusion 34. Instead, the top plug 3
The shaft 3 is attached to the fixing rod 37 having the spring 38 in the upper half of 1b.
A shaft 39 that is installed radially with respect to 9 axes and moves up and down
Is provided with a large diameter portion 53 that is thicker by an amount corresponding to the depth of the diffuser grip tool groove 32.

Further, the fixing rods 37 provided radially are also provided.
An example of is shown in FIGS. FIG. 5A is an example in which the fixing rod 37 is provided in a cross shape, and FIG. 5B is a combination of the half-moon shaped fixing rod 37.

The operation of the second embodiment thus constructed will be described again with reference to FIGS. 4 (a) and 4 (b).
FIG. 4A shows a state in which the shaft 39 is lowered and the motor casing 22 is not filled with water, the motor casing 22 is being filled with water, or the water filling is finished. ing.

FIG. 4B shows a state in which the shaft head 40 is held by the upper plug holding tool and the shaft 39 is pulled up in the direction of the arrow in the figure. In FIG. 4A, the shaft 3
The fixing rod 37 is pushed out to the large diameter portion 53 of the
Is hooked in the diffuser gripping groove 32 to mechanically fix the upper plug 31b and the diffuser 13.
The maximum pressure of the MUW used for water injection is applied, and the shaft 3
The thickness and weight of the shaft 39 and the communicating portion 41 are adjusted so that the fixing rod 37 can be hooked in the diffuser gripping groove 32 even when 9 is moved up and down.

The reactor pressure vessel 1 and the motor casing 22 are sealed by the sealing material 33 as in the first embodiment. When the upper plug 31b having the above structure is expected to have a sealing effect, the valve 36 closes the communication portion 41 by pushing the shaft 39, and at the same time, the large diameter portion 53 is fitted into the fixing rod 37, and the diffuser 13 The upper plug 31b is mechanically fixed to.

On the other hand, when the motor casing 22 is filled with water and the upper plug 31b is pulled out, the shaft 3
By pulling 9, the valve 36 separates from the communication portion 41, and at the same time, the large diameter portion 53 separates from the fixed rod 37. Therefore, the fixing rod 37 enters the direction of the shaft 39, that is, the inside by the force of the spring 38, the fitting with the groove 32 for the diffuser gripping tool is released, and the upper plug 31b can be pulled out upward.

In this way, the motor casing 22
It is possible to prevent floating even when water is poured at a predetermined pressure of about 10 Kg / cm ² , which is the predetermined pressure of the MUW used when pouring water.

[0032]

As described above, in the internal pump upper plug device of the present invention, it is possible to prevent the upper plug from rising due to the water injection pressure during water injection.
Further, it is not necessary to reduce the pressure of the MUW used for water injection, and the decompression mechanism is not needed.

Therefore, the reliability of water injection into the motor casing at the time of regular inspection is improved, and at the same time, the decompression operation is not required, so that the working time can be shortened and the burden on the worker can be reduced.

[Brief description of drawings]

FIG. 1 (a) is a structural diagram showing an internal pump upper plug in a first embodiment of an internal pump upper plug device according to the present invention, and FIG. 1 (b) is a structural diagram showing a diffuser.

FIG. 2 is a vertical sectional view for explaining a groove for a diffuser grip provided in a diffuser in the first embodiment.

FIG. 3 is a vertical sectional view for explaining fitting of the internal pump upper plug and the diffuser in the first embodiment.

FIG. 4 is a longitudinal sectional view showing a second embodiment of the internal pump upper plug device according to the present invention.

FIG. 5 (a) is a plan view showing an embodiment in which the fixing rod of the internal pump upper plug device of the second embodiment has a cruciform shape, and FIG. 5 (b) is a half-moon shaped fixing rod. The top view which shows the Example in case of a shape.

FIG. 6 is a vertical cross-sectional view for explaining the installation state of the internal pump.

FIG. 7 is a vertical cross-sectional view for explaining the structure of an internal pump.

FIG. 8 is a vertical cross-sectional view showing a conventional example of an internal pump upper plug device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Reactor pressure vessel 1a ... Lower mirror 1b ... Penetration part 2 ... Reactor core 3 ... Downcomer 4 ... Internal pump 10 ... Pump part 11 ... Motor part 12 ... Impeller 13, 13a
... Diffuser 15 ... Pump shaft 15a ... Projection part 16 ... Nozzle 17 ... Stretch tube 18 ... Stretch tube nut 19 ... Secondary seal 20 ... Rotor 21 ... Stator 22 ... Motor casing 22a ... Bottom plate 23 ... Cooling water circulation piping 24 ... Auxiliary cover 25 ... Coupling stud nut 26 ... Main stud nut 31, 31a, 31b ... Upper plug 32 ... Diffuser grip tool groove 33 ... Sealing material 34 ... Protrusion 35 ... Notch 36 ... Valve 37 ... Fixing rod 38 ... Spring 39 ... Shaft 40 ... Shaft head 41 ... Communication part 50 ... Diffuser grip 51 ... Hook 52 ... Cable 53 ... Large diameter part

Claims (2)

[Claims] 1. An internal pump upper plug which is vertically provided by penetrating a lower mirror portion of a reactor pressure vessel and which closes a motor casing of an internal pump having an opening on an inner surface of a lower mirror portion of the reactor pressure vessel. In the device, a cylindrical upper half part forming a main part of the internal pump upper plug body, a protrusion provided on the upper half part, and a continuous part of the upper half part with a smaller diameter than the upper half part. A cylindrical lower half portion having an inverted conical portion hanging down from the lower end of the upper half portion, and a notch portion which is concentrically surrounding the impeller of the internal pump and which is vertically formed for inserting the projection portion. An internal pump upper plug device comprising: a diffuser having a groove portion formed in a circumferential direction in communication with the cutout portion. 2. An internal pump upper plug, which is vertically provided by penetrating a lower mirror portion of a reactor pressure vessel and has an opening in an inner surface of the lower mirror portion of the reactor pressure vessel to close a motor casing of the internal pump. In the device, a cylindrical upper half part forming a main part of the internal pump upper plug body and a spring provided in the upper half part and movable in a horizontal direction by a spring, concentrically with the impeller of the internal pump. A fixing rod fitted in a groove portion provided in the circumferential direction of a diffuser surrounded by, and provided so as to vertically move through the fixing rod and the upper half portion, and partly for pushing the fixing rod. A shaft having a large diameter portion, and a cylindrical lower half portion having an inverted conical portion that is continuous with the upper half portion and has a smaller diameter than the upper half portion and hangs from the lower end of the upper half portion. Interface -Plug device on the top of the internal pump.