JPH0771393A - Recirculating pump built in atomic reactor - Google Patents

Abstract

PURPOSE:To provide a recirculating pump built in an atomic reaction, stably rotating in a pump rotating speed range at the time of normal driving even when weight of a rotor is increased and improvement of inertia is attempted. CONSTITUTION:A pump part provided on the bottom part of an atomic reactor pressure container and circulating a coolant, a motor part to drive this pump part and a thrust disc 18 constituted by forming a plural number of through holes in the diametrical direction are provided. Additionally, a lower part thrust bearing 20 arranged on the lower part of this thrust disc 18, a plugging device 11 provided on the lower part of the thrust disc 18 and to prevent reverse rotation of the pump part, an internal cylinder 29 to engage with this plugging device 11 and a pressure holding tool 26 arranged in a clearance part between this plugging device 11 and the internal cylinder 29 are furnished.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a built-in reactor type recirculation pump which is attached to the bottom of a reactor pressure vessel and circulates a reactor coolant.

[0002]

2. Description of the Related Art In general, a recirculation pump with a built-in reactor (hereinafter referred to as RIP) is used to forcibly circulate a coolant in a reactor pressure vessel (hereinafter referred to as RPV) 1 as shown in FIG. It is a thing. The RIP 27 is mainly composed of a motor section 2 and a pump section 3 which are in a flooded state.
Here, the pump unit 3 has a pump impeller 14 which is attached to the upper portion of the shaft 13 and guides the coolant from above to below, and a diffuser 4 which is attached inside the RPV 1 and diffuses the coolant to be discharged.

On the other hand, although the motor unit 2 and the inside of the RPV 1 are in communication with each other, purge water is constantly supplied into the motor unit 2 from a purge water pipe 15 attached to an upper portion of a motor casing 5 for housing the motor unit 2. Since the purged water flows upward on the outer peripheral surface of the shaft 13, R
Water quality is separated from the coolant in PV1.

A secondary seal 16 is provided on the upper portion of the motor casing 5, and when the motor unit 2 is removed, pressure water is supplied to the secondary seal 16 via a pressure water supply pipe 17. By expanding the secondary seal 16 and bringing it into close contact with the outer peripheral surface of the shaft 13, the coolant inside the RPV 1 is prevented from leaking from the lower portion of the motor casing 5.

A thrust disk 18 is provided at the lower end of the shaft 13 via a bolt 28. The shaft 13 is inserted into the rotor 7, and the shaft 1
A pump impeller 14 is detachably attached to the upper end of the pump 3, and the pump impeller 14 is rotated as the shaft 13 rotates.
Rotates. Therefore, pump impeller 14 and shaft 1
Since the rotor 7 and the thrust disk 18 rotate integrally, the upper thrust bearing 19 is on the upper side of the thrust disk 18 and the lower thrust bearing 20 is on the lower side.
Are installed respectively.

The thrust disk 18 is provided with a plurality of through holes 24 radially in the radial direction. Shaft 13
Since the thrust disk 18 rotates with the rotation of, the fluid in the through hole 24 is driven to the outside of the thrust disk 18 by the centrifugal force due to the difference in radius between the inside and the outside of the through hole 24. At this time, the pressure of the fluid is higher on the outer side than on the inner side of the thrust disk 18. Due to this driving force, the cooling water moves upward in the motor casing 5, removes heat of the motor unit 2 while passing through the motor unit 2, and is then guided to the outside from the motor unit cooling outlet pipe 9. The cooling water provided for this heat removal is cooled by a heat exchanger (not shown) provided outside the RIP 27, and then the motor cooling inlet pipe 1 is again provided.
0 is guided into the thrust disk 18 via a flow path (not shown) provided in the motor casing 5.

At this time, a part of the cooling water moves downward on the outer side of the thrust disk 18, passes through the lower thrust bearing 20 and the reverse rotation preventing device 11, and is again thrust disk 18.
May be guided inside. This flow rate is the motor unit 2
Therefore, it is necessary to limit this short-circuit flow rate as much as possible because it is guided to the inside of the thrust disk 18 again without flowing through it. For this reason, this short-circuited flow path is narrowed, and a cylindrical pressure dam is installed to limit this flow. This pressure dam will be described with reference to FIG. 6, which shows the lower part of the RIP 27 in detail. As described above, the cooling water that has obtained the driving force by the normal thrust disk 18 cools the motor part 2 through the flow path indicated by the arrow A in the figure, and then flows in from the motor part cooling inlet pipe 10 via the external heat exchanger. Then, it is again guided to the inside of the thrust disk 18 through the flow path indicated by arrow B in the figure.

On the other hand, the flow path of the short-circuited flow is shown by an arrow C in the figure. Therefore, in order to narrow the short circuit channel, it is preferable to provide a member for narrowing the channel somewhere in this channel. That is the pressure dam 8. This pressure dam 8 is a motor cover 2
It is fixed at 5.

Next, the pressure and load applied to the structure near the pressure dam 8 and the thrust disk 18 will be described.
Multiple RIP27s are installed in the lower part of the reactor in order to enhance the safety of the reactor. Even if one or two RIP27s are shut down, it is designed so that the remaining RIP27s can safely operate the reactors. There is. However, one or two RIP2
When the pump 7 is stopped, the coolant flows backward through the pump unit 3, and this flow causes the pump unit 3 to receive a force in the reverse rotation direction. At this time, if the pump unit 3 rotates in the reverse direction,
Further, the backflow rate increases and the coolant flowing to the core decreases. Therefore, in order to suppress the backflow of the stopped pump unit 3 and to send the coolant to the core portion as much as possible, it is necessary to prevent the pump unit 3 from rotating in the reverse direction. Therefore, the reverse rotation prevention device 11 is provided. ing.

The reverse rotation preventing device 11 is for preventing the shaft 13 from rotating in the reverse direction, and a cam (not shown) contacting the inner cylinder 29 is caused by the force of a spring (not shown). Prevents reverse rotation by engaging in a wedge shape. During normal operation, this cam receives an external force due to centrifugal force and overcomes the spring force, so that the inner cylinder 29 and the cam do not contact each other.

The rotating body composed of the pump impeller 14, the shaft 13, the rotor 7 and the thrust disk 18 is a thrust disk 1 when it is stopped and at low speed.
It is supported by the lower thrust bearing 20 via 8. Further, at the time of high speed rotation, the rotating body is lifted by the reaction force of the fluid in the pump impeller 14, so that the upper thrust bearing 1
9 will be supported. The balance at the time of lifting is determined by the weight of the rotating body, the reaction force of the fluid, and the pressure distribution of the coolant around the thrust disk 18.

FIG. 7 shows the balance of forces acting on the rotating body. In the figure, F2 is its own weight, F1 is the reaction force of the pump impeller 14,
It increases as the rotation speed increases. P1 and P2 represent the pressure of the fluid, P1 is the pressure on the discharge side of the thrust disk 18, P2 is the pressure on the suction side, and has a relationship of P1> P2. Further, S1 and S2 represent areas, S1 is an area under the thrust disk 18 where the pressure P2 is applied, and S2 is an area under the thrust disk 18 where the pressure P1 is applied. Therefore, the downward force applied to the rotating body is as shown in the first formula below. Note that S is the area S1 and the area S2.
Is the sum of

[0013]

## EQU00001 ## Downward force = F2-F1 + P1.times.S-P2.times.S1-P1.times.S2 = F2-F1 + S1.times. (P1-P2) (1) Therefore, in addition to the own weight F2, rotation also occurs due to the pressure difference of the coolant. The numbers will receive a downward force.

However, when the rotational speed of the pump impeller 14 increases, F1 increases and there is a rotational speed at which the downward force becomes zero. In such a state, the pump impeller 14, the shaft 13, the rotor 7 and the thrust disk 1
Since the rotating body composed of 8 is not supported by either the upper thrust bearing 19 or the lower thrust bearing 20,
The vibration of the rotating body becomes large.

The rotating body is laterally supported by an upper radial bearing 21 and a lower radial bearing 22 shown in FIG. If the RIP 27 loses power due to some factor during normal operation, the RIP 27 loses its driving force, and the rotational speed gradually decreases. On the other hand, in the core portion, heat is still generated due to the decay heat of the fuel. Therefore, it is unfavorable for safety that the RIP 27 slows down and the flow rate of the coolant supplied to the core portion decreases because the fuel temperature rises.

Therefore, the flywheel 23 shown in FIG.
Etc. are provided to increase the weight of the rotating body of the RIP 27 and to increase the inertia moment of the rotating system, thereby reducing the decrease in the rotational speed.

[0017]

In the prior art described above, since the weight of the rotating body increases due to the high inertia, the rotational speed when the rotating body floats up due to the fluid reaction force of the pump impeller is higher than that of the conventional art. There is a possibility that it will become higher and will enter the rotational speed range of the RIP in normal operation. When the rotating body is lifted up in the normal operation region, the vibration of the RIP becomes large during the normal operation, which is not preferable for safe operation of the RIP.

The present invention has been made in consideration of the above conventional circumstances, and an object thereof is to increase the rotational speed of the RIP by increasing the weight of the rotating body of the RIP to achieve high inertia. It provides a RIP that stably rotates in the area.

[0019]

In order to achieve the above-mentioned object, the RIP of the present invention is, in the invention described in claim 1, provided at the bottom of a reactor pressure vessel, and a coolant is circulated in the reactor pressure vessel. A pump part, a motor part for driving the pump impeller of the pump part via a shaft, a thrust disk provided in the lower part of the shaft and having a plurality of through holes formed in the radial direction, and a thrust disk for supporting the thrust disk. For this purpose, a lower thrust bearing disposed under the thrust disk, a reverse rotation preventing device provided under the thrust disk for preventing reverse rotation of the pump portion, and a spline that meshes with the reverse rotation preventing device on the outer surface. In a reactor built-in type recirculation pump having a cylinder and a motor cover for enclosing the motor part while supporting the reverse rotation prevention device, the reverse rotation prevention is provided. There is provided a reactor internal recirculating pump disposed pressure retainer in the gap portion of the location and the inner cylinder.

According to the second aspect of the invention, a pump portion provided at the bottom of the reactor pressure vessel for circulating a coolant in the reactor pressure vessel, and a motor for driving the pump portion via a shaft. Section, a thrust disk provided in the lower portion of the shaft and having a plurality of through holes formed in the radial direction, a lower thrust bearing arranged in the lower portion of the thrust disk to support the thrust disk, and the lower portion of the thrust disk. A reverse rotation preventive device for preventing the reverse rotation of the pump portion, an inner cylinder having a spline meshing with the reverse rotation prevention device on the outer surface, and a motor enclosing the motor portion while supporting the reverse rotation prevention device. In a nuclear reactor built-in recirculation pump having a cover, the through hole formed in the thrust disk has a downward inclination toward the radially outer side. There is provided a reactor internal recirculating pump comprising Te.

According to a third aspect of the invention, there is provided the reactor built-in type recirculation pump according to the first aspect, wherein the pressure holder is integrally provided on the motor cover. The invention according to claim 4 provides the recirculation pump with built-in nuclear reactor according to claim 1, wherein the pressure retainer is provided integrally with the reverse rotation preventing device.

[0022]

In the RIP having the above-mentioned structure, in the inventions described in claims 1, 3 and 4, the pressure dam is arranged in the gap between the reverse rotation preventing device and the inner cylinder close to the axial center. In the invention of (1), by guiding the high-pressure cooling water after passing through the through-hole, upward pressure is applied to the thrust disk, the pump rotation speed at which the floating phenomenon occurs is reduced, and in the pump rotation speed region during normal operation. It can be stably rotated without vibrating.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIG. 1. In FIG. 1, the same parts as those in FIG. In FIG. 1, a cylindrical pressure dam 26 is arranged inside the reverse rotation preventing device 11. Therefore, it is possible to apply a pressure similar to the pressure from the upper direction even from the lower direction by using the coolant discharge pressure. Therefore, the weight of R increased due to the high inertia.
The rotation speed of the IP27 when it floats can be lowered,
The pump can be stably rotated without vibration in the pump rotation speed range during normal operation.

Next, FIG. 2 shows a second embodiment of the present invention. In FIG. 2, the same parts as those in FIG. In FIG. 2A, the through hole 31 of the thrust disk 18 is provided obliquely downward toward the outside. Therefore, the coolant discharged by the centrifugal force is discharged downward from the through hole 31. Since the reaction force at that time works upward, RIP2
7 is effective for lifting, and in the present invention as well, the rotation speed of the RIP 27, which has increased in weight due to high inertia, can be lowered when the RIP 27 is lifted. Therefore, it is possible to rotate the pump stably without vibration in the pump rotation speed range during normal operation. Note that FIG.
The figure which shows the DD line arrow of (a) is shown.

Furthermore, FIG. 3 shows a third embodiment of the present invention. In FIG. 3, the cylindrical pressure dam 26 is integrated with the motor cover 25. Therefore, since the pressure dam 26 and the motor cover 25 can be taken out at the same time during the regular inspection, the handling operation can be simplified, and at the same time, the pump can be stably rotated in the pump rotation speed region during normal operation without vibration. Is possible.

FIG. 4 shows a fourth embodiment of the present invention. Figure 4
In FIG. 1, the pressure dam 26 is arranged below the reverse rotation preventing device 11. With this configuration, by narrowing the gap between the pressure dam 26 and the inner cylinder 29, it is possible to set the area where the discharge pressure of the fluid from the thrust disk 18 is applied to the lower side of the rotating body to the inner side as much as possible. As a result, the area of the lower surface of the rotating body to which the discharge pressure of the coolant from the thrust disk 18 is applied is increased, and the floating effect is increased. Therefore, it is possible to rotate the pump stably without vibration in the pump rotation speed range during normal operation.

[0027]

As described above, in the reactor built-in type recirculation pump of the present invention, the cylindrical pressure dam is arranged inside the reverse rotation preventing device to effectively use the coolant, and Also, a pressure similar to the pressure from above can be applied, and stable rotation can be achieved without vibration in the pump rotation speed region during normal operation.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing a first embodiment of a recirculation pump with built-in nuclear reactor of the present invention.

FIG. 2A is a vertical sectional view showing a second embodiment of the recirculation pump with built-in nuclear reactor of the present invention, and FIG. 2B is a DD view of FIG.
FIG.

FIG. 3 is a vertical sectional view showing a third embodiment of the recirculation pump with built-in nuclear reactor of the present invention.

FIG. 4 is a vertical sectional view showing a fourth embodiment of the recirculation pump with built-in nuclear reactor of the present invention.

FIG. 5 is a vertical cross-sectional view showing a conventional example of a recirculation pump with a built-in nuclear reactor.

FIG. 6 is an enlarged vertical cross-sectional view showing a portion of a symbol VI in FIG.

FIG. 7 shows a conventional example of a recirculation pump with a built-in reactor,
The conceptual diagram which shows the pressure and load which act on a rotating body.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Reactor pressure vessel (RPV) 2 ... Motor part 3 ... Pump part 4 ... Diffuser 5 ... Motor casing 6 ... Stator 7 ... Rotor 8 ... Pressure dam 9 ... Motor part cooling outlet pipe 10 ... Motor part cooling inlet pipe 11 ... Reverse rotation prevention device 12 ... Hollow motor shaft 13 ... Shaft 14 ... Pump impeller 15 ... Purge water piping

Claims (4)

[Claims] 1. A pump unit provided at the bottom of a reactor pressure vessel for circulating a coolant in the reactor pressure vessel, a motor unit for driving a pump impeller of the pump unit via a shaft, and a shaft. A thrust disk provided in the lower portion and having a plurality of through holes formed in the radial direction, a lower thrust bearing provided in the lower portion of the thrust disk to support the thrust disk, and a pump portion provided in the lower portion of the thrust disk. An atomizer having a reverse rotation preventing device for preventing reverse rotation, an inner cylinder having an outer surface formed with a spline that meshes with the reverse rotation preventing device, and a motor cover for enclosing the motor unit while supporting the reverse rotation preventing device. A built-in-reactor recirculation pump, characterized in that a pressure retainer is disposed in a gap between the reverse rotation preventing device and the inner cylinder. . 2. A pump section provided at the bottom of the reactor pressure vessel for circulating a coolant in the reactor pressure vessel, and a motor section for driving the pump section via a shaft.
A thrust disk provided in the lower portion of the shaft and having a plurality of through holes formed in the radial direction, a lower thrust bearing arranged in the lower portion of the thrust disk for supporting the thrust disk, and a lower thrust bearing provided in the lower portion of the thrust disk. A reverse rotation preventive device for preventing reverse rotation of the pump portion, an inner cylinder having an outer surface formed with a spline that meshes with the reverse rotation prevention device, and a motor cover for enclosing the motor portion while supporting the reverse rotation prevention device. In the internal-reactor-type recirculation pump, the through-hole formed in the thrust disk is inclined downward toward the outside in the radial direction. 3. The reactor built-in recirculation pump according to claim 1, wherein the pressure holder is provided integrally with the motor cover. 4. The recirculation pump with a built-in nuclear reactor according to claim 1, wherein the pressure retainer is provided integrally with a reverse rotation prevention device.