JPH05142381A - Recirculation pump system with built-in nuclear reactor - Google Patents

Abstract

PURPOSE:To prevent a recirculation pump from being abruptly lowered in revolution, and thereby enable cooling a furnace core to be kept on by disposing a cooling water pump in the pipe line for a cooling water supply connected to the pump motor section of recirculation pump system with a built-in nuclear reactor. CONSTITUTION:A cooling water pump 33 driven by a steam turbine is, for example, disposed in the cooling water pipe line 31 of a heat exchanger 30, and is connected to a cooling water inlet port 32 provided for the lower section of a motor casing 8. When one of power supplies for the pump motor 6 of recirculation pump 2 with a built-in nuclear reactor is cut off, the pump impeller 7 of the pump 2 is lowered in revolution. Since cooling water pressurized by the pump 33 is fed into the pump 2, an auxiliary impeller 19 is driven by cooling water. By this constitution, the pump 2 is neither abruptly lowered in revolution, nor suspended. This configuration thereby dies not result in passage resistance which impairs the other flow of refrigerant by the pump 2 normally operated, any fuel rod will never increase in temperature.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the operation of a reactor built-in recirculation pump installed in a boiling water reactor, and more particularly to the safe operation of the reactor when the pump motor power is lost.

[0002]

2. Description of the Related Art In the latest boiling water reactor, the bottom of the reactor pressure vessel 1 is replaced by a recirculation pump installed outside the conventional reactor as shown in the partially cut front view of FIG. A plurality of built-in nuclear reactor type recirculation pumps 2 are directly installed in the reactor. By the operation of the recirculation pump 2 with built-in reactor, the reactor coolant is sucked through the downcomer portion 4 as shown by the arrow 3, discharged to the lower part of the core 5, and introduced and circulated in the core 5. Reactor built-in recirculation pump 2
Are installed around the reactor core 5 in the reactor pressure vessel 1, and transmit the rotational driving force of the directly connected pump motor 6 to the pump impeller 7, and the rotation of the pump impeller 7 causes the reactor pressure vessel 1 to rotate. The reactor coolant inside is forced to circulate.

As shown in the structural cross-sectional view of FIG. 3, the internal-reactor recirculation pump 2 has a pump impeller 7 projecting inward from the bottom of the reactor pressure vessel 1 and downward from the bottom of the reactor pressure vessel 1. A pump motor 6 that projects and is mounted inside a motor casing 8 that is configured integrally with the reactor pressure vessel 1 and that rotationally drives a pump impeller 7, and a reverse rotation prevention device 9 that is installed inside the lower end of the motor casing 8. It is configured. Furthermore, the pump part is a pump impeller 7
The lower part of the pump shaft is inserted into the pump motor 6
A pump diffuser 12 fixed to the upper end of 10 and coaxial with the pump impeller 7 on the outer circumference of the pump impeller 7 is fixed to the reactor pressure vessel 1 at the outer circumference and the lower end.

A pump motor 6, which is a motor portion, is fixed to a motor shaft 13 fixed via a key (not shown) below the pump shaft 10 penetrating the shaft center and an outer periphery of the motor shaft 13. It is composed of a rotor 14, a motor outer cylinder 15 mounted and fixed to the inner circumference of the motor casing 8, and a stator 16 fixed to the inner circumference of the motor outer cylinder 15. The outer periphery of the upper end of the motor shaft 13 is supported by an upper radial bearing 17 fixed to the inner periphery of the motor outer cylinder 15, and the outer periphery of the lower end of the motor shaft 13 is supported by a lower radial bearing 18 in the radial direction. On the other hand, the auxiliary impeller is located below the motor shaft 13.
An upper thrust bearing 20 is attached to a motor outer cylinder 15 that is directly connected to the auxiliary impeller 19 and faces the upper surface of the auxiliary impeller 19, and a motor lower lid 21 fixed to the lower end of the motor casing 8 via a seal (not shown). A lower thrust bearing 22 is provided between the auxiliary impeller 19 and the auxiliary impeller 19.

By operating the recirculation pump 2 with a built-in reactor, the reaction force of the reactor coolant discharged by the pump impeller 7 in the direction indicated by the arrow 3 in FIG. The pump shaft 10, rotor 14, pump impeller 7, auxiliary impeller when stationary
The loads of the rotating members such as 19 are supported by the lower thrust bearing 22. An auxiliary lid 23 is installed in the center of the motor lower lid 21 via a seal (not shown), and a reverse rotation preventing device 9 is installed on the outer periphery of the auxiliary lid 23. The reverse rotation preventing device 9, the auxiliary lid 23, and the auxiliary impeller. A suction port 24 of the auxiliary impeller 19 is provided in a central portion surrounded by 19. A power cable (not shown) is pulled out airtightly through the motor lower lid 21.

Further, a motor upper chamber 25 is formed in an upper portion of the motor outer cylinder 15, and a through hole 26 communicating with the motor upper chamber 25 is provided in an upper portion of the motor casing 8. The through hole 26 is provided in the through hole 26. A pipe 27 for injecting high-pressure purge water is connected inside the motor. Further, a cooling water outlet 28 penetrates through the motor casing 8 below the through hole 26, and
It is connected to a heat exchanger 30 which is installed outside the reactor built-in recirculation pump 2 by 29. In addition, the heat exchanger
The other side of 30 is connected by a pipe 31 to a cooling water inlet 32 on the side surface of the suction port 24 provided in the lower portion of the motor casing 8.

In the reactor built-in type recirculation pump 2 having the above-described structure, the pump motor 6 is supplied by the purge water injected from the pipe 27 into the pump motor 6 at high pressure.
The inside is shut off from the inside of the reactor pressure vessel 1. Further, inside the pump motor 6, the cooling water is sucked by the auxiliary impeller 19 from the piping 31 through the cooling water inlet 32 and the suction port 24 by operating the reactor built-in recirculation pump 2. 6 circulates inside 6 and pipes 29 from the cooling water outlet 28
It is refluxed to the heat exchanger 30 via and cooled.

Further, when the recirculation pump 2 with built-in nuclear reactor is adopted, the inertia of the rotating portion is smaller than that of the conventional recirculation pump due to its structure, and therefore the responsiveness to speed control is excellent. On the other hand, when the power supply is cut off during operation, the rotation speed decreases rapidly. Therefore, design the power supply device etc. so that the pump impeller 7 is rotating and the damping rate is at a specified value as much as possible. However, the temperature of the fuel rods (not shown) forming the core 5 is prevented from rising rapidly.

In the reverse rotation prevention device 9, the power supply to a part of the reactor built-in recirculation pumps 2 out of a plurality of the reactor built-in recirculation pumps 2 is cut off,
The power supply of the other internal reactor recirculation pumps 2 is normal, and when operating normally, the power supply was cut off due to the discharge pressure of these normal internal reactor recirculation pumps 2 The recirculation pump 2 with a built-in nuclear reactor is for preventing a reverse flow due to the reverse flow by adding a flow in the reverse direction to the normal to the pump impeller 7. This structure is generally of the cam latch type, and a large number of movable cams are provided in the rotating portion, and the structure is such that it is expanded in the radial direction by the centrifugal force accompanying the rotation. On the other hand, there is a cylindrical member on the stationary side, and a cam shape is formed so that the pump impeller 7 cannot rotate reversely.

[0010]

In the reactor built-in type recirculation pump 2, when the power supply to the pump motor 6 is cut off, the rotation of the pump impeller 7 does not occur because the inertia of the rotating portion is small. It slows down rapidly and eventually stops. In this case, until the power is restored, core cooling in the nuclear reactor must rely on cooling by natural circulation. At this time, the reactor coolant takes the flow path indicated by an arrow 3 in FIG. 2, but at this time, the reactor built-in type recirculation pump 2 stopped.
For the natural circulation flow, there is a problem that it acts as flow path resistance and weakens the natural circulation force, which impedes cooling of the core.

The object of the present invention is to supply the cooling water for the pump motor to the reactor built-in recirculation pump under pressure by an external pump, and to assist the reactor built-in recirculation pump when the power supply is cut off. It is an object of the present invention to provide a recirculation pump system with a built-in reactor that cools the core by preventing a rapid decrease in rotation of the recirculation pump with a built-in reactor by driving an impeller.

[0012]

[MEANS FOR SOLVING THE PROBLEMS] A built-in-reactor recirculation pump including a motor installed at the bottom of a reactor pressure vessel and integrally attached to a recirculation pump, and a motor part of the built-in reactor recirculation pump. In a nuclear reactor built-in recirculation pump system in which a pipe connecting cooling equipment for supplying cooling water is connected, a cooling water pump is inserted in a cooling water supply pipe connected to the motor unit.

[0013]

[Operation] During normal operation of the reactor, the cooling water of the pump part of the recirculation pump with built-in reactor is sent from the heat exchanger to the auxiliary impeller by the cooling water pump, and is circulated in the pump motor by the auxiliary impeller for cooling. .. If the power supply is cut off, the rotational force of the pump motor will be lost, but the rotational force of the auxiliary impeller by the cooling water pumped from the cooling water pump will rotate the internal recirculation pump of the reactor, The forced circulation function of the reactor coolant is maintained and the temperature rise of the core is prevented.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. It should be noted that the same components as those of the above-described conventional technique are denoted by the same reference numerals and detailed description thereof will be omitted. As shown in the sectional view of the configuration of FIG.
Is attached to the inside of the pump impeller 7 projecting inward from the bottom of the reactor pressure vessel 1 and the motor casing 8 projecting downward from the bottom of the reactor pressure vessel 1 and integrally formed with the reactor pressure vessel 1. , A pump motor 6 for rotationally driving the pump impeller 7, and a reverse rotation preventing device 9 mounted inside the lower end of the motor casing 8. An auxiliary impeller 19 is directly connected to a lower portion of the motor shaft 13 of the pump motor 6. ing.

An upper thrust bearing 20 is provided on the motor outer cylinder 15 facing the upper surface of the auxiliary impeller 19, a motor lower lid 21 fixed to the lower end of the motor casing 8 via a seal (not shown), and the auxiliary impeller 19 are provided. A lower thrust bearing 22 is provided between and.

Further, a suction port 24 for the auxiliary impeller 19 is provided at a central portion surrounded by the auxiliary lid 23 attached to the center of the motor lower lid 21 and the auxiliary impeller 19. Further, a motor upper chamber 25 is formed in an upper portion of the motor outer cylinder 15, and a through hole 26 communicating with the motor upper chamber 25 is provided in an upper portion of the motor casing 8. The through hole 26 has a through hole 26. A pipe 27 for injecting high-pressure purge water is connected inside. Further, a cooling water outlet 28 is provided below the through hole 26 of the motor casing 8 and is connected to a heat exchanger 30 by a cooling water pipe 29. On the other side of the heat exchanger 30, a cooling water pipe 31 and a cooling water pump 33, which is inserted into the cooling water pipe 31 and is driven by, for example, a steam turbine, are provided below the motor casing 8 on the side surface of the suction port 24. It is connected to the water inlet 32. A steam pipe 35 having a steam valve 34 is connected to the cooling water pump 33.

Next, the operation of the above configuration will be described. When the power supply to the pump motor 6 of the recirculation pump 2 with built-in reactor is normal, the flow of the reactor coolant generated by the pump impeller 7 driven by the pump motor 6 is sufficiently supplied to the core 5. Then, the core 5 is cooled and the reactor output is extracted. At this time, the auxiliary impeller 19 sucks the cooling water sent to the suction port 24 through the heat exchanger 30, the cooling water pipe 31, and the cooling water pump 33 to circulate and cool the inside of the pump motor 6. And return it to the heat exchanger 30 again.

If the power supply to the pump motor 6 of a part of the internal reactor recirculation pump 2 is cut off for some reason, the rotation of the pump impeller 7 of the internal reactor recirculation pump 2 will decrease. Then, the circulation flow rate of the reactor coolant to the core 5 by the internal reactor recirculation pump 2 is reduced. However, since the cooling water pressurized by the steam turbine-driven cooling water pump 33 is sent to the suction port 24 of the reactor-internal recirculation pump 2, the auxiliary impeller 19 is driven by this cooling water. It As a result, the rapid decrease in rotation of the recirculation pump 2 with built-in nuclear reactor does not occur, and it does not stop.

Therefore, at this time, since it does not serve as a flow path resistance which obstructs the flow of the reactor coolant in the core 5 by the other reactor built-in type recirculation pump 2 during normal operation, the core 5
The temperature of the fuel rods constituting the fuel cell does not rise. Further, by controlling the cooling water pump 33, the pressure and flow rate of the cooling water are adjusted to cool the pump motor 6 when the power source is normal, or to maintain or stop the rotation of the internal reactor recirculation pump 2 when the power source is lost. Since it becomes possible to easily control the attenuation rate and so on, it is not necessary to consider inertia during operation by the power supply device or the like.

Further, according to the present invention, the reverse rotation of the internal reactor recirculation pump 2 whose power supply is cut off due to the discharge pressure of the other internal reactor recirculation pump 2 during normal operation does not occur. It is also possible to eliminate the need for the reverse rotation prevention device 9. In the above-described embodiment, the cooling water pump 33 is described as being driven by a steam turbine, but it may be driven by a motor as long as it has an emergency power supply separate from the power supply of the recirculation pump 2 with a built-in reactor. Well, with steam turbine drive, even when power is lost, steam from the reactor or
With the auxiliary steam, it is possible to always perform its function without any trouble.

[0021]

As described above, according to the present invention, the power supply system of the internal reactor recirculation pump is disturbed, and one of the plurality of internal reactor recirculation pumps installed in the reactor pressure vessel is affected. Even if all or all of the power supply is lost, the rotation of the reactor internal recirculation pump does not rapidly decrease and stop, and the flow of the reactor coolant is not obstructed. It has the effect of improving safety and reliability of reactor operation without affecting cooling.

[Brief description of drawings]

FIG. 1 is a sectional view showing the configuration of a recirculation pump system with built-in nuclear reactor according to an embodiment of the present invention.

FIG. 2 is a partially cut front view showing an outline of a boiling water reactor.

FIG. 3 is a configuration cross-sectional view of a conventional recirculation pump system with built-in nuclear reactor.

[Explanation of symbols]

1 ... Reactor pressure vessel, 2 ... Reactor built-in recirculation pump,
3 ... Reactor coolant flow path, 4 ... Downcomer section, 5 ... Reactor core, 6 ... Pump motor, 7 ... Pump impeller, 8 ... Motor casing, 9 ... Reverse rotation prevention device, 10 ... Pump shaft, 11 ... Guide vane, 12 ... Pump diffuser, 13 ... Motor shaft, 14 ... Rotor, 15 ... Motor outer cylinder, 16 ... Stator, 17 ... Upper radial bearing, 18 ... Lower radial bearing, 19 ... Auxiliary impeller, 20 ... Upper thrust bearing, 21 … Motor lower lid, 22… Lower thrust bearing, 23… Auxiliary lid, 24… Suction port, 25… Motor upper chamber, 26… Through hole, 27… Piping, 28… Cooling water outlet, 29,
31 ... Cooling water piping, 30 ... Heat exchanger, 32 ... Cooling water inlet, 33 ...
Cooling water pump, 34 ... Steam valve, 35 ... Steam piping.

Claims (1)

[Claims] Claim: What is claimed is: 1. A reactor internal recirculation pump comprising a motor installed at the bottom of a reactor pressure vessel and integrally attached to a recirculation pump, and cooling water supplied to the motor part of the reactor internal recirculation pump. In the recirculation pump system with built-in reactor, which is connected with piping for connecting cooling equipment, a cooling water pump is provided in the cooling water supply pipe connected with the motor section. system.