JPS60114607A - Nuclear reactor feedwater controller for boiling-water type 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 system for a boiling water nuclear reactor that maintains the water level in the boiling water reactor at a preset water level. .

[Technical background of the invention]

Generally, when operating a boiling water nuclear reactor, the level of the coolant in the reactor, that is, the reactor water, is maintained constant in order to ensure safe operation. This water level maintenance is also required when reactor power changes.

For this reason, conventionally, the water level of the reactor water has been maintained using a reactor water supply control system as shown in FIG.

In the figure, reference numeral 1 indicates a boiling water reactor, and the steam generated in the boiling water reactor 1 is sent to a turbine 3 through a main steam flow path 2, which rotates the turbine 3 and generates electricity from a generator 40. Served. The steam flowing out of this turbine 3 is transferred to a condenser 5
The water is condensed in the boiling water reactor 1, and is then fed by the feed water pump 6, and is fed into the boiling water reactor 1 through the feed water channel 8 as feed water while the flow rate is controlled by the feed water regulating valve 7, which is a type of feed water flow rate controller. sent to.

The water level of the reactor water in the boiling water reactor 1 is maintained by the water level gauge 9.
This is done by adjusting the opening degree of the water supply regulating valve 7 while detecting the water level.

The opening degree control of this water supply regulating valve 7 is performed automatically.

That is, the main steam flow rate detector 10 provided in the main steam flow path 2
The main steam flow rate is detected by the water supply flow path 8, and the water supply flow rate is detected by the water supply flow rate detector 11 provided in the water supply flow path 8. Next, the mismatch signal calculator 12 calculates the difference between the main steam flow rate signal 10a and the feed water flow rate signal 11a respectively emitted from both detectors 10 and 11, and multiplies the difference by a predetermined constant as the mismatch gain GM. Mismatch signal 1
Emit 2a. After that, the feedback signal calculator 13
Then, this mismatch signal 12a and the water level signal 9a sent from the water level gauge 9 are added together and sent to the water supply flow rate controller 14 as a feedback signal 13a. The reason why the mismatch signal 12a is added to the water level signal 9a as this feedback signal 13a is that a change in the water level in the reactor 1 occurs when there is a difference between the main steam flow rate and the feed water flow rate. This is to cause the reactor water level 12a to act as a preceding element for changes in the reactor water level, thereby suppressing fluctuations in the reactor water level due to disturbances such as when changing the output of the reactor 1. Then, the water supply flow rate controller 14 calculates the difference between the feedback signal 13a and the set water level signal 15a, and the KPI type controller 16 calculates a command signal 14a that makes the difference zero, and sends it to the water supply adjustment valve 7. The water supply regulating valve 7 that receives this command signal 14a is adjusted to open or close according to the value of the command signal 14a, thereby changing the water supply flow rate. This change in the feed water flow rate is fed back in the same manner as described above, and is continuously changed so that the feed water flow rate maintains the water level of the reactor 1 constant.

[Problems with background technology]

In this way, in the conventional device, the water supply regulating valve 7 is opened and closed by feedback to maintain the water supply flow rate at an appropriate value.

In order to reduce the influence of disturbances such as changes in the reactor output direction on this water supply flow rate, the mismatch gain GM in the mismatch signal calculator 12 may be increased.

On the other hand, if this mismatch gain GM is increased, the timing of opening and closing of the water supply regulating valve 7 may not match the valve opening degree that maintains the actual required water supply flow rate, so it is not possible to sufficiently increase the mismatch gain GM. The problem was that I couldn't do it.

[Purpose of the invention]

The present invention was made in view of these points, and even if a disturbance such as a sudden change in the reactor output occurs, fluctuations in the water level inside the reactor are suppressed to a minimum, and the present invention always operates stably to maintain an appropriate water supply flow rate. The purpose of the present invention is to provide a reactor water supply control device for a boiling water reactor that is capable of maintaining high reliability.

[Summary of the invention]

The reactor feed water control device for a boiling water reactor of the present invention further includes a change rate of the main steam flow rate signal in addition to the conventional device, subtracts this change rate from the mismatch signal, and sends it to a feedback signal calculator as a water level correction signal. A correction calculator is provided to send out a correct command signal to the target at all times.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to FIGS. 2 and 3.

FIG. 2 shows the configuration of the apparatus of the present invention, and the same parts as in FIG. 1 are given the same reference numerals.

As shown in the figure, in this embodiment, the mismatch signal calculator 1
A correction computing unit 17 is provided at the rear of 2 and in the length. The correction calculator 17 includes a rate-of-change calculator 18 that performs a differential operation on the change in the live steam flow rate signal 10a emitted from the main steam flow rate detector 10, and a predetermined constant for the output 18a of the rate-of-change calculator 18. It has an upper and lower limit limiter 19 that applies an upper and lower limit limit gate to the value multiplied by Correction signal 17
It is sent to the feedback signal calculator 13 as a signal.

Other configurations are similar to the conventional example.

Next, the operation of this embodiment will be explained.

A case where the reactor output suddenly decreases will be explained with reference to FIG.

When the reactor output suddenly decreases, as shown in Figure 3(a),
The main steam flow rate signal 10a suddenly decreases. As a result, the feed water flow rate signal 11a becomes larger than the main steam flow rate signal 10a, and the mismatch signal 12a calculated by the mismatch signal calculator 12 becomes positive and decreases the feed water flow rate, as shown in FIG. Change.

At the same time, the main steam flow rate change signal 19a calculated by the change rate calculator 18 becomes negative as the main steam flow rate signal 10a rapidly decreases, as shown in FIG.

The water level correction signal 17a obtained by subtracting the negative main steam flow rate change signal 19a from the positive mismatch signal 12a is, as shown in FIG. It becomes a positive value larger by the amount of the main steam flow rate change rate signal 19a than the value (broken line in FIG. 3(d)), and becomes a value that reduces the water supply flow rate.

Therefore, the feedback signal 13a determined by the feedback signal calculator 13 becomes larger than before, and the difference from the set water level signal 15a becomes larger, and the command signal 14a issued from the regulator 14 also becomes larger. The water supply regulating valve 7 is rapidly closed.

As a result, as shown in the same figure (e), the water supply flow rate signal 1
1a decreases earlier than the conventional value (dotted line in FIG. 6(e)).

Therefore, as shown in Figure (f), 'Reactor water level signal 9
a rises above the set water level (O level in figure (f)) because the feed water flow rate temporarily becomes larger than the main steam flow rate;
As shown in (e) of the same figure, the feed water flow rate decreases earlier than in the conventional case, so that the increase in the water level signal is suppressed to be smaller than that of the conventional reactor water level signal (the broken line in the same figure).

In this way, fluctuations in the water level inside the reactor 1 are reduced,
Holding at a set water level is carried out.

On the other hand, when the reactor output suddenly increases, the water level in the reactor 1 is kept at the set level by suppressing fluctuations in the water level by a completely opposite response to the sudden decrease.

[Effects of the Invention] Since the present invention is constructed and operates in this manner,
Even if a disturbance such as a sudden change in reactor output occurs, fluctuations in the water level inside the reactor can be suppressed to a small level, and it can always operate stably and maintain an appropriate water supply flow rate. Even if it is set to a small value in the direction of more stability, the main steam change rate signal can widen (suppress) fluctuations in the reactor water level, resulting in more stable control and higher reliability. play.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a conventional reactor feed water control device for a boiling water reactor, FIG. 2 is a block diagram showing an embodiment of the reactor feed water control device of the present invention, and FIGS. (f) shows characteristic diagrams of various signals produced by the device of the present invention. DESCRIPTION OF SYMBOLS 1... Nuclear reactor, 7... Water supply adjustment valve (water supply flow rate controller), 9... Water level gauge, 9a... Water level signal, 10...
Main steam flow rate detector, 10a... Main steam flow rate signal, 11
...Water supply flow rate detector, lla...Water supply flow rate signal, 1
2... Mismatch signal calculator, 12a... Mismatch signal, 13... Feedback signal calculator, 13a
...Feedback signal, 14...Adjuster, 14a
...Command signal, 15a...Setting water level signal, 17...
・Correction calculator, 17a... Water level correction signal, 18...
Rate of change calculator, 19... Upper and lower limit limiter, 19a Main steam flow rate change signal. Applicant's agent Kiyoshi Inomata Figure 3

Claims (1)

[Scope of Claims] 1. A main steam flow rate detector that detects the flow rate of main steam flowing out from the boiling water reactor and generates a main steam flow rate signal, and a main steam flow rate detector that detects the flow rate of feed water flowing into the boiling water reactor. a feedwater flow rate detector that detects and issues a feedwater flow rate signal, a water level gauge that detects the water level in the boiling water reactor and issues a water level signal, and a difference between the main steam flow rate signal and the feedwater flow rate signal. Furthermore, a mismatch signal calculator multiplies a mismatch gain to generate a mismatch signal, a feedback signal calculator adds the mismatch signal and the water level signal to generate a feedback signal, and calculates the difference between this feedback signal and the set water level. In a reactor feed water control system for a boiling water reactor, the main steam A boiling water reactor comprising a correction calculator that calculates the rate of change of the flow rate signal, subtracts this rate of change from the mismatch signal, and sends the result as a water level correction signal to the feedback signal calculator. Reactor water supply control device. 2. The correction calculator consists of a rate-of-change calculator that performs differential calculations on changes in the main steam flow rate signal, and a value obtained by multiplying the output of this rate-of-change calculator by a predetermined constant by upper and lower limit gates. 2. A reactor feed water control system for a boiling water reactor according to claim 1, further comprising an upper and lower limit limiter for generating a steam flow rate change rate signal.