JPS5886490A - Flow rate control device - 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 the Invention The present invention relates to a flow control system for controlling recirculation flow in a boiling water nuclear reactor having multiple recirculation loops.

(b) Conventional technology Output control of boiling water reactors can be controlled by controlling the neutron flux in the reactor by absorbing it with control rods, or by changing the flow rate of reactor water, which is the moderator in the reactor. The recirculation flow rate may be controlled. The former is to set the distribution shape of the reactor output so that it becomes a predetermined distribution, and the latter is to set the distribution shape of the reactor power distribution characteristic so that it becomes a predetermined distribution, and the latter is to set the distribution shape of the reactor power distribution characteristic so that the output It increases or decreases the size of .

There is a recirculation flow rate control device that controls the output of a nuclear reactor by recirculating this reactor water. The recirculation flow control device sucks reactor water from the reactor, pressurizes it, and controls it to forcefully circulate it back to the reactor. Usually, it controls the recirculation pump motor that drives the recirculation pump. That control is expressed. That is, it controls the frequency of the generator (MG set generator) that powers the recirculation pump motor, thereby controlling the speed of the recirculation pump motor. Generally, a boiling water reactor has a recirculation loop and a B2 system, so the recirculation pumps of the two systems are controlled simultaneously.

This recirculation flow control device is installed after the reactor is started up.
It will start up after a while. That is, when the reactor is started, the output is gradually increased through natural circulation, and when the reactor output reaches a predetermined value, for example, about 25 liters, only one recirculation pump is started. Then, the minimum speed is set to, for example, about 2 degrees, and when that becomes stable, the other recirculation pump is started and this is also set to the minimum speed, for example, 20 degrees. After this, the speed of the two recirculation pumps is controlled by the recirculation flow control device to increase or decrease the reactor output, and the control rods are operated as necessary to change the shape of the reactor's output to achieve a predetermined level. The reactor is operated to achieve a reactor output of

However, recently, even in nuclear power plants, it has become necessary to increase or decrease their output in accordance with the load. In other words, it is customary for nuclear power plants to operate on a base load, with almost no changes in load.However, as the capacity of nuclear power plants' power generation facilities is gradually increasing, nuclear power plants are operated exclusively for pace loads. I'm starting to not be able to go to school anymore. On the other hand, there is a simultaneous need for improvements to make the operation of nuclear power plants safer and more reliable, and improvements in nuclear reactor output control have been desired.

(c) Purpose of the Invention Therefore, the object of the present invention is to coordinately control a plurality of recirculation pumps when controlling the recirculation flow rate to increase or decrease the output of a nuclear reactor, thereby improving the safety of the nuclear reactor. And, there is a possibility to obtain a flow control device that improves operating efficiency while maintaining reliability.

(d) Structure of the Invention The present invention will be described below with reference to an embodiment shown in the drawings. FIG. 1 is a system configuration diagram in which the flow rate control device of the present invention is applied to a recirculation flow rate control system B of a Ct nuclear reactor. 9 Recirculation mass flow control system A shown in the figure.

B uses a variable frequency motor-generator device (hereinafter referred to as MG upper set).

In FIG. 1, steam generated by the heat generated by the nuclear reaction in the core 50 of the reactor 1 is sent to the turbine through the main steam pipe 51, but the moderator flow rate (core flow rate) flowing through the reactor core 5o is It is pressurized by three recirculation pumps, three recirculation flow control systems, B and B, and is driven via jet pump 2. The recirculation pumps 3A, 3B are connected to recirculation pump motors 4A, 48, respectively, and the recirculation pump motors 4A, 4B are connected to the MG upper set electric machine 5A.
, 5B. The MO upper set electric machines 5A and 5B are connected to the MG upper set motors 7A and 7BK via fluid couplings 6 and 6B. Exciters 8 and 8B are connected to these MG upper set motors 7A and 7B,
MG Kamisetsu Denki 5A.

Supply field to 5B. Meanwhile, 5 MG set generators,
Rotation speed detectors 9A and 9B are attached to 5B, and the signal of rotation speed detector 9 and 9B is transferred to hand 1 automatic switch 14A.
, 14BK sent.

Next, the rotational speed request signal from the main controller 16 in the flow rate control device C or the output signal from the distributor 23 is input to the manual/automatic switching devices 14A and 14B. When the rotation speed request signal from the main controller 16 is used, it is automatic, and when the output signal from the distributor 23 is used, it is manual. First, in the case of automatic, the rotation speed detector 9
The rotational speed obtained from the driver 9B is compared with the request signal from the main controller 16, and the difference is calculated by the controllers 13A and 13B.
Give K. On the other hand, in the case of 9 manual, converters 24A, 24
The rotation speed is obtained from the rotation speed detector 9B via the rotation speed detector 9B, and the deviation from the setting signal from the setting device 20 is obtained by the adder 21.

Then, the output signal of the adder 21 is inputted to the distributor 23 via the control element 22 to control the recirculation flow rate.

B is divided into two systems, so the signals distributed here are sent to the controller 13 via manual/automatic switchers 14A and 14B.
A. 138K is input.

The output signals of controllers 13A and 13B are respectively output from controller 1.
2, A, 12B and compensators 11A, IIB, are input to the scoop tube controller 10A, IOB, respectively, and the output signals of the scoop tube controller 10A, IOH are sent to the scoop tube drive device 16A.

16B.

Assume now that the MG upper set motives 7A and 7B are activated. Assume that the MG upper set motors 7A and 7B are operated at a constant rotation speed (for example, 101,000 rpm).
The shaft of the fluid joint 6A acts as the input shaft of the fluid joint 6B.

The output shaft of 6B is the axis of M () set generator 5 people, 5B, and the torque TMA + T M jl of 6 fluid couplings, 6B Nyo D, MG upper set motor 7A, 7B is M
Drive torque TQ of G upper set electric machines 5A and 5B.

Transmitted as TGI. The torques Tea and Tom are expressed by the following equations.

'ram=/A(8Gmu)・Tnu...-α)T@m
= fm (Ram) ・Twm... (2) Here, the function fmt/m is the torque transmission efficiency of 6 fluid couplings and 6B, and the variables 8Gm and 80m are MG upper set electric machine 5 The speed is 5B.

In this way, when the MG upper set electric machine rotates and generates electric power, the electric power is transmitted to the recirculation pump motors 4 and 4, respectively.
Power is transmitted to B and rotates the recirculation pump motor 4, 4B. Here, when the MG set electric motors 71 to 7B are rotating at a constant rotation speed, the torque is transmitted to the MG upper set electric motors 5 and 5B using equations (1) and (2) above, so the rotation speed is Since the torque transmission efficiency changes depending on the torque transmission efficiency Im, h, the frequency of the electric power generated in the MG upper set electric machine 5B also changes. As a result, MG-nit generator 5A, 5
A recirculation pump motor 4A electrically coupled to B.

This means that the rotation speed of 4B is variable.

Furthermore, since the recirculation pump 3, 3B is mechanically connected to the recirculation pump motor 4, 4B, the flow rate of water discharged by the recirculation pump changes depending on the change in rotational speed. The recirculation 3jlj flow rate is controlled.

In other words, 5 MG generators.

The rotational speed detector 5B detects the rotational speed of the MG upper set electric machine 5B, and sends the signal to the manual/automatic switch 14A, 14B.
Since the recirculation flow rate is also sent to 4A and 24B, the recirculation flow rate is controlled to match the target value.

In this case, in order to avoid asymmetrical operation in the two loops of the recirculation flow control system A and B, until the rotational speed of the three recirculation pumps and the recirculation pump 3B reaches a certain value or higher (for example, 45-speed),
1 Set the manual/automatic switch 14A, 14B to the manual position.

FIG. 2 is a characteristic diagram of the rotational speeds of the recirculation pumps 3A and 3B and their operating ranges.

Both recirculation pumps 3A and 3Bd have a minimum operating speed, which must be maintained to maintain the integrity of the equipment. In FIG. 2, line segments ab and ac represent the operating speed ranges of the three recirculation pumps and 3B, respectively. On the other hand, the shaded areas A and B in FIG. 2 are ranges in which the operating speeds of the recirculation pumps 3A and 3B differ greatly from each other, that is, they are asymmetric areas, and the operation in this area is Not done.

Therefore, it is usually desirable to keep the two recirculation pumps on the line segment ad at the same rotation speed. Therefore,
In the present invention, the request signal is distributed equally by the distributor 23.

During manual operation, the setting device 20 is operated to change the set value. The rotational speed of the two recirculation pumps 3 and 3B inputted to the converter 24^24B is calculated based on the set value of the setter 20 and the adder 21 performs the following arithmetic processing.

Δ=D-(gom+801)...(3) Then, this deviation signal Δ is input to the controller 22, and the distributor 23 sends it to the two recirculation pumps, Man and B. A rotational speed request signal is calculated so that the speed is constant. This calculation result is sent to manual/automatic switching devices 14A and 14B. Below, the outputs of the manual/automatic switch 14A, 14B are input to the controllers 13A, 13B, and the maximum, minimum,
The rate of change is limited and output to the controllers 12A and 12B. After predetermined control calculations are performed by the controllers 12A and 12B, their outputs are input to the compensator 11^11B, where calculations such as nonlinear compensation of the fluid coupling are performed. Then, the output is input to the scoop tube controller 10A and IOH, and the scoop tube controller 10A and IOB operate the scoop tube drive device 16,
16B and operates the scoop pipe to adjust the slip (torque transmission efficiency fm,/m) between the input shaft and output shaft of the fluid couplings 6A and 6B. In this way, the two recirculation pumps 3, 3B can be operated at equal speeds at all times.

Next, the rotational speed of the recirculation pump is set to a constant value (e.g. 45-
), the output of the main controller 16 is always set to the speed of the two recirculation pumps so that the output of the main controller 16 is automatically controlled, and the manual/automatic switch 14AJ4
Switch both B to the automatic side. The operations after this Kyo-sho can be performed by changing the settings of the main controller 16.

In the above embodiment, a variable frequency motor-generator device is used for the recirculation flow rate control system, but the recirculation flow rate may also be controlled by adjusting the opening degree of the outlet valve of the recirculation pump. Needless to say, this is dangerous even when an axial flow pump called an internal pump is applied inside a nuclear reactor.

(e) Effects of the Invention As described above, according to the present invention, the recirculation flow rate can be distributed evenly and the output can be increased and decreased in a balanced manner between the two recirculation flow rate control systems. That is, since asymmetrical operation of the two recirculation flow rate control systems can be avoided, it is possible to provide a safe and highly reliable flow rate control device that can quickly respond to increases and decreases in output.

[Brief explanation of the drawing]

FIG. 1 is a system configuration diagram in which the flow rate control device of the present invention is applied to a recirculation control system of a nuclear reactor, and FIG. 2 is a characteristic diagram showing the operating range of a recirculation pump. 1... Nuclear reactor, 2... Jet pump, 3... Recirculation pump, 4... MG upper set motor, 5... MG
Upper set electric machine, 6... Fluid coupling, 7... Recirculation pump motor, 8... Exciter, 9... Rotation speed detector,
20... Setting device, 21, 22... Controller, 23...
・Distributor, 24...Converter, 16...Main controller, C
...Flow control device. (7317) Representative Patent Attorney Kensuke Norichika (and 1 other person) Figure 1 Hei 68? 8 Figure 2 O rotation for phlegm <B)

Claims (1)

[Scope of Claims] A plurality of recirculation flow rate control systems are provided to control the output of a boiling water reactor by controlling the recirculation flow rate using a recirculation pump, and a control command is given to each of these recirculation flow rate control systems. , a setter for setting a reference raw reference value of the recirculation flow rate, an adder for obtaining a deviation between the sum of the recirculation flow rates in each of the recirculation pumps and the reference value, and a recirculation flow rate corresponding to this deviation. 9. A flow control device comprising: a distributor that evenly distributes a command to the plurality of recirculation flow control systems.