JPS62169084A - Flow controller for coolant of nuclear reactor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a nuclear reactor coolant flow rate control device, and is particularly suitable for a primary cooling system of a tank-type fast breeder reactor (hereinafter referred to as FBR). This invention relates to a flow rate control device.

[Conventional technology]

The conventional FBR primary cooling system flow rate control method is described in "Hitachi Hyoron J Vo467, No. 853 of 11 (November 1985).
As shown on pages 858 to 858, each loop of the cooling system had a pump rotation speed control device for continuous control.

For this reason, as a rotation speed control device for a large pump drive motor, M-G sets or thyristor power supplies that generate variable frequencies are installed as many as the number of loops in the cooling system.

[Problem that the invention seeks to solve]

In the above conventional technology, a large-scale pump rotation speed control device is required for each cooling system loop, and as the reactor output scale increases, the number of loops also increases, so the number of control devices tends to increase. .

The purpose of the present invention is to rationalize the circulation pump rotation speed control device while maintaining the continuous control characteristics of the reactor coolant flow rate, and to significantly simplify the equipment, thereby achieving greater economy, reliability, and maintainability. It's about trying.

[Means for solving problems]

The flow of the primary coolant in a tank-type FBR is mixed within the tank, except for the piping that connects each circulation pump outlet to the core inlet.
It's called IHX. ), the flow rate is evenly distributed.

[-Therefore, in order to control the reactor coolant flow rate and the IHX coolant flow rate, it is not necessary to control the rotation speed of the circulation pumps of each loop equally.

In view of the above-mentioned characteristics, the present invention simplifies the circulation pump rotation speed control device by using constant speed rotation pumps for a portion of the primary coolant circulation pumps and using continuous rotation control pumps for the remaining pumps. This has been achieved.

[Operation] Figures 2(a) and 2(b) show the flow of coolant in the tank-type FBRO tank and the operation of the pump partial number control system according to the present invention.
1. In a tank-type FBR, the reactor core 2 is located in the center of the vessel (tank) 1, and the cooling system loop system 11 (x3A to 3D and circulation pumps 48 to 41) is located around it. will be placed accordingly.

The flow of coolant in the tank is based on the reactor output (part of the reactor core).
→ Upper plenum 11 → IHX primary inlet → IHXI secondary outlet - → Lower part V nano, 12 → Circulation pump 4 → Check valve 9
→ Reactor inlet (lower core) → Circulate through the path inside the reactor core 2.

Here, in tank type ii' B II, circulation pump 4
8 to 41) are connected by piping from the outlet to the reactor inlet.In the primary cooling system, each loop flows in a mixed manner in a plenum inside the tank, so there is a difference in the circulation pump rotation speed of each loop. Even at this time, an equal flow rate of coolant flows through each IHX 3A to 3D.

In view of the characteristics of the primary cooling system of the tank-type FBR, the present invention controls the flow rate of the primary cooling system by rotating some pumps at a constant speed, unlike the conventional system of controlling the number of rotations of all pumps. The key to controlling the system is to control the rotation speed of n of the N primary cooling system circulation pumps, and the rest! ri(N-n>
The table rotates at a constant speed. The reactor coolant flow rate is controlled by changing the constant speed stepwise by a combination of continuous rotation speed control of n pumps, starting/stopping of (N-n) pumps, or changing the number of poles. As a result, the flow rates of each IHX are uniform; the heat output generated in the reactor core 2 is evenly transported; a large-scale pump control device can be reduced, and reliability can be improved.

〔Example〕

Hereinafter, one embodiment of the present invention will be explained in detail.

The embodiment shown in Fig. 1 has four loops in the cooling system, and among 54 primary cooling system circulation pumps 48 to 4D, 4B and 4C4 are fixed-speed rotation pumps, and four people and 4D are operated by a continuous rotation speed control device. This figure shows a case where the pump is equipped with the following.

Drive motor 41B for constant speed rotation pumps 4B and 4C.

410 are connected to the power supply 5 through the circuit breakers 6B and 6I, respectively.
Connected to B and 5C.

On the other hand, the pump motor 41A continuously controls the rotation speed.

41D, each continuous rotation speed control device 8A.

8D is connected, and a rotation speed command signal is given to the rotation speed command device 7. Continuous rotation speed control device 8A.

8D has power supplies 5A and 5D connected to circuit breakers 6A and 6, respectively.
Connected via D.

The operation of this embodiment will be explained below.

When the circuit breakers 6A to 6D are turned on and the pumps 4A to 4D are started, the constant speed rotation pumps 4B, 4C rotate at the rated speed, and the continuous rotation speed control pumps 4A and 4D start the continuous rotation speed control device 8.
It rotates at the minimum rotation speed specified by A and 8D.

The rotation speed command device 7 sends the pump rotation speed command signal 7 as a function of the plant output command signal to the rotation speed control devices 8A, 8.
Give to D.

FIG. 3 shows an example in which the continuous rotation speed control devices 8A and 8D are implemented as an MG set.

In FIG. 3, the rotation speed command signal 7A has its upper and lower limits limited by a rotation speed limiter 81, and then is compared with the rotation speed output from a tachometer 87 and provided to a rotation speed controller 82 as a rotation speed deviation. The controller performs calculations such as proportional integral and the like, and sends a control signal to the scoop tube drive device 83.

The fluid coupling 85 is installed between the drive motor 84 rotating at a constant speed and the alternating current generator @86, and the force transmission torque changes depending on the scoop pipe position □, so that the rotation speed of the alternator can be continuously changed.

Therefore, by driving the scoop pipe of the fluid coupling with a control signal, the generation frequency of the alternator, that is, the drive frequency of the pump motor 41 changes, and the pump rotation speed changes.

The automatic voltage regulator 88 sends a signal proportional to the rotational speed to the exciter 89, and applies a voltage proportional to the frequency to the pump motor.

As described above, the continuous rotation speed control pump 4A.

The rotation speed of 4D is controlled according to a command signal from a rotation speed command device.

The primary coolant flow rate is set as a function of reactor power, examples of which are shown in FIGS. 4-7.

In Figure 4, the rotational speed of the four pumps is set to be the same at the rated output, and as the output decreases, the rotational speed of the continuous rotational speed control pumps 4A and 4D is reduced, and the constant speed rotational pumps 4B and 4C are set to the rated output. This shows the case where the rotation speed remains unchanged.

The flow rates of the constant speed rotary pumps 4B and 4C tend to increase as the pressure loss decreases as the rotation speed of the continuous rotation speed control pumps 4A and 4D decreases, but the flow rate of the primary cooling system as a whole tends to increase depending on the setting program. changes according to As a result, the primary cooling system flow rate can be continuously controlled between approximately 60% and 100% even though a constant speed rotation pump is present.

Figure 5 shows the constant speed rotary pump 4 at approximately 70% output (point ■).
The case where either B or 4C is stopped is shown. The rotation speed command device commands an increase in the rotation speed of the continuous rotation speed pump to compensate for the decrease in flow rate due to the stoppage of the constant speed rotation pump.
The flow rate changes according to the set program. This results in
The primary system flow rate can be continuously controlled between about 40% and 100%.

Figure 6 shows that one constant-speed rotary pump is stopped at approximately 70% output (point ■), and the other constant-speed rotary pump is stopped at approximately 45% output (point ■). This shows the case where

As a result, the primary cooling system flow rate is approximately 20% to 100%.
Continuous control is possible between

In order to further expand the flow rate control range, one of the pumps with continuous rotation speed control is stopped and only one circulating pump is continuously controlled in rotation speed.

The pump rotation speed command and pump start/stop program for the output-flow rate as described above are set by the rotation speed command device.

FIG. 7 shows an embodiment in which a pole change type is used as a drive motor for a constant speed rotation pump.

An i-return conversion type motor has windings with different numbers of poles, and by switching the excited windings, a constant rotation speed can be obtained in stages according to the number of poles, and is equipped with a pole number conversion switching device. It is known as a motor.

This example shows the case of a pole number conversion type motor of 4 poles and 8 poles, and by switching from 4 pole excitation to 8 pole excitation, υ
, the rotational speed decreases to about 1/2.

In Fig. 7, if we consider the case where the output is decreased from the rated output, one of the drive motors of the constant speed rotation pump (
For example, the number of poles of 41B) is changed from 4 to 8 poles. The decrease in flow rate due to this is compensated by an increase in the continuous rotation speed control pump rotation speed.

Regarding point (2), the other constant speed rotation pump drive motor 41
Change the number of poles of C from 4 poles to 8 poles.

Regarding point (2), one constant-speed rotary pump drive motor (for example, 4
1B).

At point ■, the other constant speed rotary pump, drive motor 411
0i is stopped, and the flow rate is controlled only by the continuous speed control pump.

The order of switching the points from ■ to ■ does not necessarily have to be the same as above; instead of changing the number of poles of the motor 41C at the point ■, stop the motor 41B, and change the number of poles of the motor 41C at the point ■. Also good.

Although the embodiments of the present invention have been described above, it goes without saying that the following cases are also included in the present invention.

(1) Although the relationship between the reactor output and the coolant flow rate has been described as being proportional, it may be any function.

(2> Although the case where there are four cooling system circulation pumps and four intermediate heat exchangers each has been described, the number is not particularly important.

(3) A plurality of continuous rotation speed control pumps do not need to be controlled because they always rotate at the same time, and it is also possible to control the rotation speed individually.

(4) Coolant flow rate control is an example of 1 rotation speed signal feedback.Although all explanations have been given, the flow rate signal is fed to the part 1. 2' may be used, or both may be used together.

Open loop control without feedback of signals is also possible.

〔Effect of the invention〕

The effects of the present invention are as follows.

(1) By making some of the multiple cooling system circulation pumps rotate at a constant speed, it is possible to eliminate the need for large-scale and complicated pump motor continuous rotation speed control devices, which has significant economic effects such as reducing equipment costs and building space. .

(2) By reducing the number of pump motor continuous rotation speed control devices described above, maintenance becomes easier and reliability is improved.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a control device showing an embodiment of the present invention, FIG. 2(a) is a plan view showing the flow of coolant in a tank-type FBRO tank, and FIG. 2(b) is an elevational view. FIG. 3 is a diagram showing a detailed configuration example of the rotation speed control device, and FIGS. 4 to 7 are graphs showing the flow rate at each output due to the operation of the embodiment of the present invention. 1... Container, 2... Reactor core, 3A, 3
B, 3C. 3D...Intermediate heat exchanger, 4A, 4B, 4C, 4D...
・Coolant circulation pump, 5A, 5B, 5C, 5D... Power supply, 6A, 6B, 6C, 6D... Breaker, 7...
Rotation speed command device, 8A, 8D...Rotation speed control device. 41A, 41B, 41C, 41D... Pump driving terms 2 mouth (phantom Z3riJ Taku 4 f Fig. 2 Poka (ga) viscous 7 Fig. 0 5Q
100 output ζ2ノ

Claims (1)

[Claims] 1. A plurality of coolant circulation pumps that feed coolant to the reactor core and a plurality of heat exchangers through which the coolant passes are provided in the same container, and the coolant circulation pump A nuclear reactor coolant flow rate control device, wherein the drive motor is a nuclear reactor equipped with a continuous rotation speed control device, wherein a portion of the plurality of coolant circulation pumps are constant speed rotation pumps. 2. In claim 1, the drive motor of the constant speed rotary pump is characterized by being equipped with a switching control device that can freely switch the constant speed stage to a plurality of constant speeds with different rotational speeds. Reactor coolant flow control device. 3. A nuclear reactor coolant flow rate control device according to claim 2, wherein the switching control device is a pole number conversion switching control device for a drive motor.