JPS61272508A - Feed water controller for 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 (Technical Field of the Invention) The present invention relates to a reactor water supply control device for controlling a boiling water nuclear reactor to maintain a constant reactor water level.

[Technical background of the invention]

Generally, in a boiling water reactor, the reactor water level is maintained constant by changing the feed water 1ffi supplied to the reactor by a feed water pump during reactor operation.
is being carried out. In addition, when the reactor is shut down or in the early stages of reactor startup, there is no steam flowing out of the reactor and υItll drive water flows into the reactor from the control rod drive system, so reactor water is passed through the reactor coolant purification system. Reactor water is kept constant by adjusting the amount of discharged water.

In order to perform such control, a reactor water supply control device as shown in FIG. 4 has conventionally been used.

The conventional reactor water supply system M1 includes a main controller 2 which receives a reactor water level signal S1 and outputs a water supply command signal S2 to keep the water level constant at w4, and this main controller 2.
A water supply pump that adjusts the water supply flow rate of the motor-driven water supply pump 5 and the turbine-driven water supply pump 5a according to the water supply command signal S2 from the! Blowdown flow 1 which adjusts the blowdown flow rate of blowdown flow aSw valve 6° according to the water supply command signal S2 as well as the IIIIIIIII device 3! ! Ig
It is composed of a one-section valve υ controller 4.

Maintaining a constant level of reactor water using this conventional device is performed as follows.

That is, in a normal operating state when the reactor is operating and main steam is supplied to the outside of the reactor from the steam outlet 10a of the reactor pressure vessel 10, the reactor is shut down with the same amount of water supply as the amount of main steam flowing out. Time i1! ! main i to supply at t10
The water supply command signal S2 in the positive direction is output from the controller 2, and the water supply pump control 1fi3 sets the water supply control valve 7 or the steam regulating valve 7a to 1Fi1rf! in order to obtain the water supply flow rate corresponding to this water supply command signal S2. The opening command signal S3 is output. As a result, the same amount of feed water as the amount of main steam flowing out from the reactor pressure vessel 10 is transferred from the feed water pump 5 to the feed water control valve 7.
The reactor pressure vessel 10 is then returned to the reactor pressure vessel 10.

At this point, the blowdown flow rate control valve controller II 4 outputs an opening command signal S4 that completely closes the blowdown flow rate control valve 6.

In addition, when steam is not being supplied outside the reactor, such as during reactor shutdown and reactor startup/shutdown processes, control rod drive water flowing from the control rod drive system 8 into the reactor pressure vessel 10 Water level rises. Therefore, a water supply command signal S in the negative direction is sent from the main controller 2 to suppress the upper arm of this reactor water.
2 is output. and blowdown Rfl control valve ul
6014 outputs an opening command signal S4 for opening the blowdown flow rate control valve 6 in order to obtain a blowdown flow rate corresponding to the water supply command signal S2 in the negative direction. As a result, reactor water passes through the reactor cooling U1 material purification system 9 to the condenser 11.
is discharged to. At this point, the feedwater pump controller 3 is outputting the opening command signal S3 to fully close the feedwater control valve 7 or the steam control valve 7a, and the feedwater pumps 5, 5a are stopped.

[Problems with background technology]

However, this conventional device 43 has the following problems when controlling the water level when steam is not being supplied from the reactor pressure vessel 10 during reactor shutdown and startup/shutdown process.

FIGS. 5(a) to 5(d) show the behavior of each part in the event of water level disturbance when the nuclear reactor is shut down. In the figure, from time O to tl, the water level is stable, and as shown in figure (b), the water supply command signal S2 in the negative direction (for example, -50%) is issued from the main controller I unit 2. According to the blowdown control valve instruction 111 device 4 is the blowdown control valve 6
A WI degree command signal S4 of 50% is output for a certain period of time.

As a result, the blowdown control valve 6 is maintained at a 50% open state, as shown in FIG.

In addition, the reactor water level (FIG. 2(a)) is maintained at the set reactor water level 1-1.

At time t1, as shown in FIG. 2(a), when the reactor water level falls due to a drop in the water level due to the activation of the reactor recirculation pump (not shown) or a water level disturbance G caused by other devices, the main In the mt controller 2, a deviation occurs between the set reactor water level 1-1 and the actual water level, and the PI calculator (not shown) in the main controller 2
The output of water supply command signal S2 increases in the positive direction.

Here, when this water level disturbance G is large, the output 82 of the main control Pj12 at time t2, as shown in FIG.
is a positive water supply command. At the same time, an opening command signal S3 is issued from the water supply pump controller 3 to open the water supply control valve 7 or the steam control valve 7a, and the water supply control valve 7 or the steam control valve 7a is opened as shown in FIG. be asked. The opening command signal S4 of the other blowdown flow rate control valve 6 becomes 0, and the blowdown flow ff11 becomes 0 as shown in FIG.
The one-section valve 6 is fully closed.

However, at this point, the water supply pumps 5 and 5a are stopped and no water is supplied even if the water supply control valve 7 is opened, so the water level gradually rises due to the water flowing in from the control rod drive system 8. At time t3 when the water level reaches the set reactor water level T1, the deviation between the set reactor water level H and the actual water level is reversed, and the water supply command signal S2 changes from the increasing direction to the decreasing direction, but since it has already gone too far in the positive direction, It takes a long time from time t3 to time t4 until the water supply command signal $2 becomes negative again and the blowdown control valve 6 opens. Therefore, this “re time (13~
At t4), the water level further rises, the overshoot of the water level rise becomes large, and it takes a long time for the reactor water level to stabilize at the set reactor water level H.

(Object of the invention) The present invention has been made in consideration of the above points,
To provide a reactor water supply control device capable of stably maintaining the reactor water level at a set reactor water level even if there is a water level disturbance in a state where the water supply pump is not capable of supplying water such as during reactor shutdown or early reactor startup. Reactor feed water of the present invention 1. The IJ tll device is a water supply system that maintains the reactor water level at a constant level by controlling the amount of water supplied by the water pump and the discharge flow rate by the blowdown flow control valve according to the deviation between the actual water level in the reactor pressure vessel and the set reactor water level. A main υ controller that outputs a command signal, and a water supply pump that controls the amount of water supplied according to the water supply command signal.1. II controller, and blowdown flow control valve controls t111 for controlling the discharge flow m by opening and closing the blowdown flow control valve in accordance with the water supply command signal, and the main controller ,
It is characterized by comprising a PI calculator which integrates the deviation to generate a water supply command signal and allows the saturation limit value of the integral element to be variable.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to FIGS. 1 to 3.

Figure 1 shows the reactor water supply of the present invention! , II shows the configuration of a reactor water supply system using the ill device, and particularly shows the case where one water supply pump 105 is controlled.

In FIG. 1, the reference numeral 101 is the reactor water supply control system of the present invention, and the main and sub-t11 units 102 are shown in detail in FIG.
, a water supply pump controller 103 and a blowdown flow control valve controller 104. This main controller 102 receives a reactor water level signal S indicating the actual water level from the reactor pressure vessel 110.
101 outputs a water supply command signal 3102 to the water supply pump controller 103 and the blowdown flow control valve controller 104 to keep the reactor water level constant. Further, one water supply pump controller 103 receives a water supply command signal S from the main controller 102.
Accordingly, the opening command signal S is output to the water supply control valve 107, and the other blowdown flow ff1J11 valve controller 1 is output.
04 is main 1. In response to the water supply command signal @8102 from the II 1211 device 102, an opening command signal 51o4 is output to the blowdown flow rate control valve 106. This water supply control valve 10
7 adjusts the water supply flow rate of the water supply pump 105 based on the opening command signal S 1 . Further, the blowdown flow control valve 106 adjusts the discharge flow rate of reactor water in the reactor pressure vessel 110 to be discharged to the condenser 111 through the reactor coolant purification system 109. The control rod drive system 108 supplies drive water to the tIII rod drive mechanism inside the reactor pressure vessel 110.

The main controller 102 of this embodiment will be further explained with reference to FIG.

This main controller 102 includes a water level setter 112, a deviation calculator 113. ! :P [It is composed of an arithmetic unit 114 and an f, IIIin setting device 115. This deviation calculator 113
receives the reactor water level signal 5181 from the reactor pressure vessel 110 and the set reactor water level output from the water level setter 112, calculates the deviation from the water level setting signal 8105, and calculates the deviation signal 51o6.
is output to the PI operation ♂114. This PI*fraud device 114
are a proportional calculator 116 that multiplies the input deviation signal @S1゜6 by a constant and outputs it to the adder 118, and an integrator that integrates the input deviation signal 51o6 and outputs the integrated value to the adder 118. 117, and an adder 118 that adds the output of the proportional calculator 116 and the output of the integrator 117 and outputs the result as a water supply command signal 5182. Also, integrator 1
17 has a function of setting the upper and lower limits of integration using the limit value signal S outputted from the limiter 115. And this! The II limiter 115 outputs a limit short message @51o7 so as to lower the upper limit of the positive integral when there is no water supply capacity.

Next, the operation of this embodiment having such a configuration will be explained.

Water level v control during steady operation of the nuclear reactor is performed as follows.

During steady operation of the reactor, steam generated from the reactor pressure vessel 110 is passed through the steam outlet 110a to a turbine (not shown).
Therefore, a flow rate of feed water corresponding to the flow rate of steam flowing out to the outside must be supplied into the reactor pressure vessel 110. Main controller 1 of water supply control device 101 of this embodiment
02 operates so that the deviation between the reactor water level signal S 1 and the water level setting signal S 2 from the water level setting device 112 becomes zero. Since steam usually flows out, the actual water level tends to be lower than the set reactor water level, and the output of the integrator 117 becomes a positive water supply command signal 51o2 requesting water supply. At this point, the i and II limits are not applied to the output of the integrator 117, making it possible to output up to 100% in the positive direction. This keeps the actual water level at the set reactor water level.

Further, water level control in a state where steam is not supplied to the outside of the reactor, such as during reactor shutdown and startup/shutdown process, is performed as follows.

FIG. 3 shows the behavior of each part in the case of water level disturbance in this embodiment.

When the reactor is shut down, the amount of control rod drive water flowing in from the control rod drive system 108 is reduced to the reactor pressure vessel 10.
Must be discharged from within 0.

Therefore, in this embodiment, the output S of the main controller 102 is set to a negative value that requests the discharge of reactor water, as shown from time O to tl in FIG. 3(b).

As a result, the blowdown flow rate adjustment valve controller 104 issues an opening command signal S1°4 to open the blowdown flow fit adjustment valve 106. As a result, the blowdown 1ffi valve 106 is opened as shown in FIG.
The reactor water level is maintained at the set reactor water level H as shown in FIG.

Here, if we consider the case where a water level disturbance G that significantly lowers the water level, such as when the coolant recirculation pump starts, occurs at time t1, the water level deviation signal $106 is output in the positive direction as the reactor water level signal 51o1 decreases. and the integrator 117 integrates in the positive direction. At this time, the output S 102 of the main controller 102
As shown in FIG. 3(b), the value increases with the passage of time. On the other hand, in the blowdown flow [1 open valve 106, the valve opening degree is gradually narrowed down, as shown in FIG. Then, at t2, the output of the integrator 117, that is, 51o2
becomes the output in the positive direction as shown in FIG. i:117 stops the integration, and the integrated evaporation force is maintained near the limit value of 0% until time t3.

During this period from t 1 to t 3 , not only the blowdown outflow control valve 106 but also the water supply mfI valve 107 is closed.

After time t3, the water level further rises and exceeds the set reactor water level T1, as shown in FIG. The deviation is in the negative direction, and the integrator 117 starts negative integration again. At this time, the integrator 117 is held at the limit value (O) as described above, so as shown in FIG.
As shown in , a negative water supply command signal S is immediately output.
At the same time, the blowdown flow control valve 6 is opened to suppress the water level from rising above. As a result, the overshoot of water level rise can be suppressed significantly lower than before, and fluctuations in the reactor water level caused by the water level disturbance G can be converged to the set reactor water level i (as shown in Figure (a)) in a short time. In the above embodiment, the water supply pump 105 is driven by an electric motor, and the water supply amount is controlled by a water supply adjustment valve 107 provided at the discharge port of the water supply pump 105. As shown in case 2, the same effect can be obtained by driving the water supply pump by a steam turbine and controlling the amount of water supplied by adjusting the rotational speed of the steam turbine using a steam control valve applied to the steam turbine. Of course.

〔Effect of the invention〕

In this way, the reactor water supply control device of the present invention can control the reactor water level during steady operation of the reactor. Not only in IIJTn but also in reactor water level t and lI control performed by discharging reactor water during shutdown, the reactor water level can be stably maintained at the set reactor water level regardless of the presence or absence of water level disturbance, ensuring plant safety. This has the effect of improving performance and reliability.

4. Drawing + 7) f! ! Figures 1 to 3 show an embodiment of the reactor feed water control system of the present invention, Figure 1 is a block diagram showing the water supply control system using this embodiment, and Figure 2 is the main Configuration diagram showing DI m device, Figure 3(a)~
(d) is a characteristic diagram showing the behavior of each part in response to water level disturbance in this embodiment, Figure 4 is a configuration diagram similar to Figure 1 of the conventional device, and Figure 5
This figure is a characteristic diagram similar to that shown in FIG. 3 of a conventional device.

101...Reactor feed water v4 control device, 102...Main controller, 103...Water pump 1i11 control device, 104.
... Blowdown flow rate control valve controller, 105 ... Water supply pump, 106 ... Blowdown vL amount control valve, 10
7... Water supply control valve, 110... Reactor pressure vessel, 1
14...PI performer, 115...Restrictor, 117.
...Integrator, 5181...Reactor water level signal, 5182...
・Water supply command signal.

Applicant's agent Kiyoshi Inomata ■１ Man 1 figure Figure 2 Man 3 figure II No. 4Ei7i

Claims (1)

[Claims] 1. The reactor water level is kept constant by controlling the amount of water supplied by the water supply pump and the discharge flow rate by the blowdown flow control valve according to the deviation between the actual water level in the reactor pressure vessel and the set reactor water level. a main controller that outputs a water supply command signal to be held; a water supply pump controller that controls the water supply amount according to the water supply command signal; and a blowdown flow control valve that opens and closes the blowdown flow control valve according to the water supply command signal to control the discharge The main controller includes a blowdown flow rate control valve controller for controlling the flow rate, and the main controller includes a PI calculator that integrates the deviation to generate a water supply command signal and can freely vary the saturation limit value of the integral element. A reactor water supply control system characterized by: 2. The nuclear reactor according to claim 1, wherein the PI computing unit has an integrator that integrates the deviation, and a limiter that changes the saturation limit value of the integral element by this integrator from the outside. Water supply control device.