JPS6283693A - Nuclear reactor output control method and 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 Application of the Invention] The present invention relates to a method and apparatus for controlling the power of a nuclear reactor, and in particular, to controlling the reactor power by a recirculation flow rate control system of a boiling water reactor (hereinafter referred to as BWR) plant. This invention relates to a method and device for controlling a nuclear reactor.

[Background of the invention]

Generally, when controlling the generator output in a BWR plant, that is, the turbine output, by controlling the amount of steam flowing into the turbine, it is desirable to control the reactor output at the same time. Control the reactor output by controlling the flow rate. However, when the reactor power is made to follow the turbine power demand, the neutron flux signal of the reactor will overshoot if the recirculation flow rate is changed rapidly.

There is a possibility that the reactor will scram. One method for suppressing fluctuations in this neutron flux signal is, for example, in Japanese Patent Application Laid-Open No. 54-397.
It is disclosed in Publication No. 90.

This publication discloses a reactor pressure control system for a BWR plant that can suppress fluctuations in reactor pressure due to sudden changes in steam flow rate, and FIG. 6 is an explanatory diagram of this system configuration.

In this diagram, 1 is a nuclear reactor, 2 is a turbine, 3 is a condenser, and 4 is a
, 5 and 6 are a main steam isolation valve, a turbine stop valve, and a turbine control valve provided between the reactor 1 and the turbine 2, respectively; 7 is a main steam isolation valve between the condenser 3 and the main steam isolation valve 4; A turbine bypass valve is provided, 8 is a water supply system connected between the reactor 1 and the condenser 3, 9 is a neutron flux φ,
Reactor pressure control devices 10 and 11 which receive the reactor pressure P, steam flow rate Qs, and turbine speed N as inputs are provided between the reactor pressure control device 9 and the turbine control valve 6 and turbine bypass valve 7, respectively. 12 is a recirculation pump, 13 is a recirculation system main controller operated by the load deviation output C of the reactor pressure control device 9, and a and b are A turbine control valve opening request signal and a turbine bypass valve opening request signal are shown, respectively.

Pressure control by this reactor pressure control device is performed in the reactor 1
The reactor pressure P, neutron flux φ, steam flow rate Qs, and turbine speed N are input to the reactor pressure control device 9, predetermined calculations are performed, and the outputs are used to control the turbine control valve 6, turbine bypass valve 7. This is done by controlling the recirculation pumps 12 respectively.

Here, the deviation signal between the steam flow rate Qs and the neutron flux φ is as follows:
The signal is multiplied by three element gains of proportional, integral, and differential (PID), and this signal is added to the load deviation output C to the recirculation system main controller 13. With this configuration, the recirculation flow rate is controlled according to the deviation between the steam flow rate Qs and the neutron flux φ, and as a result, a stable neutron flux response is obtained.

However, since the steam flow rate signal is used to calculate the load deviation signal C, which is the output to the recirculation system main controller 13, the influence of failure of the steam flow rate sensor.

Alternatively, it will be directly affected by noise mixed into the steam flow rate signal. Further, there are problems such as the inability to sufficiently suppress neutron flux fluctuations due to malfunction of the turbine bypass valve 7 and malfunction of the turbine control valve 6.

[Purpose of the invention]

An object of the present invention is to be able to suppress sudden changes in a neutron flux signal when controlling the output of a BWR plant using a recirculation flow rate in accordance with a load request signal, and to prevent failure of a steam flow rate sensor. An object of the present invention is to provide an output control device for a nuclear reactor that can eliminate the influence of noise mixed in a steam flow rate signal and suppress neutron flux fluctuations due to malfunction of a turbine bypass valve or the like.

[Summary of the invention]

The power control method for a nuclear reactor according to the first aspect of the present invention is a power control method for a nuclear reactor in which the reactor power is controlled by a recirculation flow rate control system of a boiling water nuclear power plant. A power control device for a nuclear reactor according to a second aspect of the present invention is characterized in that a deviation signal between a request signal and a neutron flux signal is fed back to the recirculation flow rate control system. In the reactor output control device for controlling the reactor output of a type nuclear power plant using the recirculation flow rate control system, there is a reactor pressure control device to which the JM slave reactor pressure is input and a total steam flow rate request signal is output, and a turbine output a turbine output control device which inputs the set value of , the total steam flow rate request signal and the turbine speed and outputs a turbine control valve and turbine bypass valve drive signal and a load deviation output; a neutron flux, the total steam flow rate request signal and the turbine speed; The present invention is characterized in that it has a recirculation flow rate control system which inputs the load deviation output and outputs it to the recirculation pump.

According to the present invention, a stable neutron flux response is obtained by using a deviation signal between a neutral flux signal and a total steam flow rate request signal in a recirculation flow rate control system. By using.

This eliminates the effects of sensor failure and noise mixing into sensor signals, and also provides a more stable neutron flux response even when a turbine bypass valve or the like malfunctions.

[Embodiments of the invention]

Examples will be described below.

Figure 1 shows an embodiment of the nuclear reactor power control device of the present invention.
This is an explanatory diagram showing the configuration of a nuclear reactor power control system applied to a WR plant, and the same parts as in FIG. 6 are given the same reference numerals. In this figure, 14 is a reactor pressure control device into which the reactor pressure P in the reactor 1 is input and the total steam flow rate request signal g is output; 15 is a reactor pressure control device in which the turbine 2 output is set; A turbine output control device that inputs a total steam flow rate request signal g and a turbine speed N from a turbine, sets a turbine output, and outputs a turbine adjustment valve opening request signal a, a turbine bypass valve disclosure request signal, and a load deviation output C. ,1
Reference numeral 6 indicates a recirculation flow rate control system to which the neutron flux φ, the total steam flow rate demand compensation sign g, and the load deviation output C are inputted, and a speed control signal for the recirculation pump 12 is outputted.

In the output control device of this embodiment, a steam flow rate Q is sent out depending on the reactor pressure P within the nuclear reactor 1. This steam flow rate Qs is sent to the turbine control valve 6 via the main steam isolation valve 4 and the turbine stop valve 5, and is injected to the turbine 2 as a turbine steam flow rate. On the other hand, a part of the steam flow rate Qs is sent to the condenser 3 as a turbine bypass steam flow rate, if necessary. The steam flow rate Q that passed through the condenser 3 is.

It becomes water and returns to the reactor 1 again through the water supply system 8.

The reactor output control of this BWR plant is based on the reactor pressure P inside the reactor 1! ! Total steam flow rate request signal g output from 14.

Turbine output control bag for reactor neutron flux φ and turbine speed N! ! ! 15. Performs predetermined calculations as an input to the recirculation flow rate control system 16 to control the turbine control valve 6, turbine bypass valve 7, and recirculation pump 12.

5S2 is a block diagram of the recirculation flow rate control system 16 of FIG. 1, in which 17 is a main controller, 18 is a limiter circuit, 19 is a speed controller, 20 and 21 are first-order delay elements, 22 is a dead band limiter circuit, 23 indicates a PID element, and 24 indicates a limiter circuit. In FIG. 2, the recirculation flow control system 16
The input to the main controller 17 is either the flow rate setting signal or the load deviation signal C from the turbine output control device 15, and is switched as necessary. The output of the main controller 17 which receives these signals as input is divided into two systems, A and B loops, but only one system, the A loop, is shown in FIG. The output of this main controller 17 and the rotation speed N of the recirculation pump 12.

After taking the deviation from the pump speed and passing it through the limiter circuit 18, the speed controller 19 generates a pump speed request signal.

On the other hand, the neutron flux φ of the nuclear reactor passes through the first-order lag element 20, and the deviation between this signal and the full-load flow rate request signal g, which has passed through the -th order lag element 21, is taken. This deviation signal is passed through the dead band limiter circuit 22 and the PID element 23 Go
After multiplying by (s) and further passing through the limiter circuit 24,
The difference from the above-mentioned pump speed request signal is taken and finally taken out as the recirculation flow rate request signal PLR. The speed of the recirculation pump 12 is controlled by this recirculation flow rate request signal PLR. Here, the total steam flow rate request signal g is obtained by multiplying the pressure deviation signal obtained by matching the reactor pressure P and the reactor pressure setting signal Po by a - next lead/lag element in the reactor pressure control device 14. , is a signal multiplied by the reciprocal of the pressure adjustment rate R.

FIG. 3 shows the results of determining the neutron flux response when the recirculation flow rate is changed by the flow rate setting using a BWR plant to which the reactor power control device configured as described above is applied. The horizontal axis is time, and the vertical axis is steam flow rate, neutron flux,
The recirculation flow rate is determined, and A (solid line) is the recirculation flow rate request signal PL in this embodiment, and B (dotted chain line) is the deviation between the neutron flux φ and the total steam flow rate request signal g in FIG.
The case is shown in which it is not returned to R. From the comparison of the neutron flux responses in this figure, it is found that the deviation signal between the neutron flux φ and the total steam flow rate request signal g is multiplied by the PID element 23, and the feedback of this signal is applied to the recirculation flow rate request signal PLR. It is clear that the overshoot of the neutron flux can be suppressed when the flow rate suddenly changes, and the neutron flux can be controlled more stably.

Furthermore, in order to investigate the effectiveness of the present invention, the control system of one of the eight turbine bypass valves 7 broke down, and one of the turbine bypass valves 7, which is normally fully open, became open. Figure 4 shows the results of considering the case where the horizontal axis represents time.

The vertical axis shows the steam flow rate, total steam flow rate request signal, neutron flux, and recirculation flow rate, and C (solid line) is D in the case of the present invention.
(One-dot chain line) shows the case of the conventional example.

In this way, by opening one of the turbine bypass valves 7, the steam flow rate Q increases rapidly and the reactor pressure P decreases. Therefore, the total steam flow rate request signal g decreases so as to maintain the reactor pressure P at a constant value, and the turbine control valve 6 is throttled. On the other hand, due to a temporary decrease in the reactor pressure P, the neutron flux φ initially decreases. At this time, since the deviation between the neutron flux φ and the total steam flow rate request signal g is fed back to the recirculation flow rate, the recirculation flow rate decreases. Therefore, even in a transient state where the steam flow rate Q3 suddenly increases, the recirculation flow rate does not increase sharply, so the neutron flux φ does not change significantly, and it is possible to prevent reactor shutdown due to an inadvertent scram. can.

In contrast, conventionally, the deviation signal between the steam flow rate Qs and the neutron flux φ was used in the recirculation flow rate control system, so when one valve of the turbine bypass valve 7 is opened, the steam flow rate Qs increases rapidly. As a result, the reactor pressure P decreases. Therefore, the neutron flux φ temporarily decreases. At this time, since the deviation between the neutron flux φ and the steam flow rate Qs is reflected in the recirculation flow rate, the recirculation flow rate increases. As a result, since the addition of the neutron flux φ depends on the rate of change of the re-wi reflux increase, a large fluctuation in the neutron flux φ will occur, potentially causing the reactor to reach a scram.

As described above, according to this embodiment, it is possible to suppress large fluctuations in the neutron flux φ when the recirculation flow rate suddenly changes, and at the same time, it is possible to suppress large fluctuations in the neutron flux φ when the recirculation flow rate suddenly changes. It is also possible to obtain a stable neutron flux response.

FIG. 5 shows a turbine load setting section which is a main part of another embodiment;
This is a block diagram of the turbine output control device and the reactor pressure control device 10, which are composed of a load deviation value setting section, etc. In the case of FIG. 2, the deviation signal between the total steam flow rate request signal g and the neutron flux signal The difference is that the feedback is fed back to the load deviation value setting section in the turbine output control device. In this diagram, 2
5 is a turbine load setting section, 26 is a calculation section, 27 is a load deviation value setting section, 28 is a primary lead/lag element of the reactor pressure control device 14, 29 is a pressure adjustment rate, and 30 is a low value selection circuit LVG. It shows.

The reactor pressure control device 14 multiplies the pressure deviation signal obtained by comparing the reactor pressure P and the reactor pressure setting signal Po by -next advance/lag element G1 (g) 28, and then calculates the pressure adjustment rate R29. Multiply by the reciprocal and output the total steam flow rate request signal g. The turbine adjustment valve opening request signal a is combined with the load request signal f from the turbine load setting section 25 and the reactor pressure control device 14.
Among the total steam flow rate request signals g from , the signal having a smaller value is selected. Here, the load request signal f is obtained by correcting the error correction signal d and the turbine load request signal e by correcting the deviation of the turbine speed N from the set speed. In the normal state, the error correction signal d is approximately zero, so the load request signal f can be considered as the turbine load request signal e.

Further, the load request signal e is set to the sum of the turbine load signal and the bias amount Δh of the turbine load signal. This bias amount Δh is usually 1 of the turbine load signal.
It is set to a value around 0%.

In the normal operating state, when comparing the total steam flow rate request signal g and the load request signal f in FIG. This becomes the steam flow rate request signal g, which becomes the turbine adjustment valve opening request compensation band a for supplying the steam flow rate Q5 according to the turbine load. That is, during normal operation, the total steam flow rate request signal g can be regarded as the turbine control valve opening degree request signal a. Further, the setting of the total steam flow rate request signal g is performed by the pressure setting Pa. For this reason, the turbine control valve 6 is normally controlled to maintain the reactor pressure P constant.

The turbine bypass valve 7 is used to maintain the reactor pressure P constant even if there are load fluctuations.

The turbine bypass valve 7 is controlled by the difference signal between the total steam flow rate request signal g and the turbine adjustment valve opening request signal a, that is, the turbine bypass valve opening request signal.

As described above, the valve opening degree of the turbine control valve 6 is determined by outputting the load deviation signal C from the load deviation value setting section 27 to the recirculation system main controller 17 of the recirculation flow rate control system 16 at the same time as the turbine output request. Control is performed to match the turbine output.

The reactor pressure P changes depending on the difference between the amount of steam generated by the heat of the reactor output (equivalent to the neutron flux φ) and the steam flow rate Qs output from the reactor 1.

Therefore, the reactor output is controlled by taking into account the difference signal between the neutron flux φ and the signal corresponding to the steam flow rate Qs. Here, the steam flow rate Q8 can be regarded as the above-mentioned total steam flow required compensation code g, and is further not affected by the failure of the steam flow rate sensor and the noise mixed in the sensor signal of the steam flow rate Q. In order to do this, the difference signal between the neutron flux φ and the total steam flow rate request signal g is used. That is, the difference signal between the two control variables, the total steam flow rate request signal g and the neutron flux, is multiplied by the three-element gain Gz(s), and this signal is used as the load deviation signal C.
Add to. The reason for setting the bias of Δh in the load deviation value setting section 27 is that when trying to change the turbine output, the recirculation flow rate is first changed and the atom By varying the furnace power.

This is to change the reactor pressure P, thereby changing the aforementioned total steam flow rate request signal g, and indirectly changing the valve opening degree of the turbine control valve 6.

On the other hand, as is clear from the above explanation, when the steam flow rate Qs is used instead of the total steam flow rate request signal g, the three-element gain Ga ( s) and added this signal to the load deviation signal 0 to control the recirculation flow rate, a failure of the steam flow sensor would be considered as, for example, a decrease in the steam flow tQs;
As a result, the recirculation flow rate is suppressed and the valve opening degree of the turbine control valve 6 is reduced. For this reason, the reactor output decreases even though it is desired to continue constant load operation. Similarly, the noise mixed in the steam flow rate sensor signal is compared with the neutron flux φ as a fluctuation in the steam flow rate Q, and then added to the load deviation signal C. Therefore, due to the influence of noise, the recirculation flow rate is always There was a problem with small fluctuations.

In this respect, the difference signal between the total steam flow rate request signal, which can be regarded as the steam flow rate Qs, and the reactor neutron flux φ is multiplied by a three-element gain Gz (s), and this signal is added to the load deviation signal C. Accordingly, the present invention, which controls the recirculation flow rate, can prevent the above-mentioned problems from occurring. This is exactly the same in the case of FIG.

Note that in the explanation of the nuclear reactor output control device of the example, an electronic circuit-like control block was used for convenience of comparison with a conventional analog electronic circuit control device, but a digital control block using a microcomputer etc. was used. It can also be realized by a control circuit.

According to the reactor output control device of these embodiments, it is possible to effectively suppress fluctuations in neutron flux when the recirculation flow rate suddenly changes, and also to eliminate the effects of failure of the steam flow rate sensor and noise mixed in the steam flow rate signal. It is more stable because
It becomes possible to operate the R plant. Furthermore, even if the steam and flow rate suddenly change due to failure or malfunction of the turbine bypass valve or turbine control valve, fluctuations in neutron flux can be suppressed.

〔Effect of the invention〕

The invention relates to controlling the output of a BWR plant in response to a load demand signal using a recirculation flow rate.

It is possible to suppress sudden changes in the neutron flux signal, and it is also possible to eliminate the effects of steam flow rate sensor failures, noise mixed in the steam flow rate signal, etc., and to suppress neutron flux fluctuations due to malfunctions of turbine bypass valves, etc. This makes it possible to provide a method and device for controlling the output of a nuclear reactor, which has great industrial effects.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the configuration of a reactor power control system in which an embodiment of the nuclear reactor power control device of the present invention is applied to a BWR plant, and FIG. FIG. 3 is a diagram showing the fluctuating neutron flux response of the curved recirculation flow rate. FIG. 4 is a diagram showing the neutron flux response when the steam flow rate fluctuates, and FIG. 5 is a diagram showing the output power of a nuclear reactor in which another embodiment of the nuclear reactor power control device of the present invention is applied to a turbine power control device. FIG. 6, a block diagram of a control system, is an explanatory diagram showing a system configuration of a conventional nuclear reactor power control device. 1... Nuclear reactor, 2... Turbine, 3... Condenser,
4... Top steam isolation valve, 5... Turbine valve, 6... Turbine regulator valve, 7... Turbine bypass valve, 8... Water supply system, 10... Turbine regulator valve drive mechanism, 11... turbine bypass valve drive mechanism, 12... recirculation pump,
14... Reactor pressure control device, 15... Turbine output control device, 16... Recirculation flow rate control system. Agent: Patent attorney Hiroo Nagasaki 2゛. (1 idiot) Kaya 3 eyes ε 埒道茅4 Figure-JfrItl

Claims (1)

[Claims] 1. A nuclear reactor output control method for controlling reactor output using a recirculation flow rate control system of a boiling water nuclear power plant, comprising:
A nuclear reactor output control method, characterized in that a deviation signal between a total steam flow rate request signal of a turbine control system and a neutron flux signal is fed back to the recirculation flow rate control system. 2. In a reactor power control device that controls the reactor output of a boiling water nuclear power plant equipped with a recirculation flow rate control system, the reactor pressure is input and the total steam flow rate is requested. a reactor pressure control device that outputs a signal; and a turbine output control device that receives a turbine output set value, the total steam flow rate request signal, and the turbine speed and outputs a Tabin control valve and turbine bypass valve drive signal and a load deviation output. and a recirculation flow rate control system which inputs the neutron flux, the total steam flow rate request signal, and the load deviation output and outputs it to the recirculation pump. 3. After passing the deviation signal between the total steam flow rate request signal and the neutron flux signal through a dead band limiter circuit, proportional, integral,
The output control of a nuclear reactor according to claim 2, wherein the calculation is performed by a calculation unit consisting of a differential element, and the calculation result is fed back to the output side of the pump speed controller of the recirculation flow rate control system. Device.