JPH03225298A - Nuclear reactor pressure controller - Google Patents

Abstract

PURPOSE:To prevent the contingent nuclear reactor scram by providing a bypass valve control circuit which makes control by the difference between the output signal f a circuit for calculating the steam flow of governar valves and the signal corresponding to the steam flow of the reactor. CONSTITUTION:The opening degree signals 3a, 3a' of the plural governar valves 3, 3' are respectively inputted to respective circuits 17, 17' for calculating the flow of the governar valves, by which the correction of the flow characteristics of the valves 3, 3' by the number of the operating units of the valves 3, 3' is executed and from which steam flow signals 17a, 17a' are respectively outputted. These signals 17a, 17a' are inputted to an adder 18 and are added. A turbine total steam flow signal 18a is outputted from the adder 18. This signal 18a is computed together with a steam flow request signal 12a and a bias signal 20 in an adder 19. A bypass valve is controlled by an opening degree request signal 13b outputted from this adder 19. The scram occurring in a change in the nuclear reactor pressure is effectively averted in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a nuclear reactor pressure control system, and particularly to a nuclear reactor pressure control system that can avoid inadvertent reactor scrams.

(Prior art) Generally, in a boiling water nuclear coupler, steam generated in the reactor is supplied to a turbine via multiple control valves to drive a generator, and the opening degree of a bypass valve is controlled. It is customary to provide a reactor pressure control device for pressure regulation.

By the way, in a conventional nuclear reactor pressure control device, the opening degree and flow rate of a bypass valve are controlled based on the difference between a regulating valve steam flow rate request signal and a pressure regulator output signal of a pressure control system.

(Problems to be Solved by the Invention) In the conventional reactor pressure control device, a regulating valve steam flow rate request signal is used to control the opening degree and flow rate of the bypass valve. If the control valve and bypass valve operate rapidly due to a malfunction, etc., the turbine steam flow rate may fluctuate due to a mismatch in the operating characteristics of the six valves, and in this case, the reactor pressure and neutron flux will increase. This could lead to a reactor scram.

The present invention was made with these points in mind, and even if the moderation valve and bypass valve operate rapidly, the rise in reactor pressure and neutron flux is suppressed, and inadvertent reactor scrams are prevented. The purpose of the present invention is to provide a nuclear reactor pressure control device that can perform

[Structure of the invention]

(Means for Solving the Problems) As a means for achieving the above object, the present invention provides a control valve steam flow rate calculation circuit that calculates a total control valve flow rate based on the valve opening degree of each control valve, and a control valve steam flow rate calculation circuit that calculates a total control valve flow rate based on the valve opening degree of each control valve. A steam flow rate control circuit is provided, which includes a bypass valve control circuit that controls the opening degree and flow rate of the bypass valve based on the difference between the output signal from the calculation circuit and the signal corresponding to the amount of steam sent from the reactor. It is characterized by

(Function) In the reactor pressure control device according to the present invention, a total control valve steam flow rate signal obtained based on the individual control valve opening degree is used in place of the conventional control valve steam flow rate request signal. The flow rate that should flow through the bypass valve is determined from the difference between the signal and the signal corresponding to the amount of steam sent from the reactor.

Therefore, the difference in response characteristics between the control valve and the bypass valve is corrected, and it becomes possible to continue operation while avoiding reactor scram caused by increases in reactor pressure and neutron flux.

(Example) Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

FIG. 1 shows an example of a nuclear reactor pressure control system according to the present invention, and in the figure, reference numeral 1 indicates a nuclear reactor.
The steam generated in the main steam pipe 2 and a plurality of control valves 3.
3' to the turbine 4, which drives the generator 5. Also, as shown in FIG. 1, a part of the steam generated in the reactor 1 is directly led to the condenser 8 via the bypass pipe 6 and the bypass valve 7, so that the reactor pressure is controlled. It has become.

The inlet pressure of the turbine 4 is detected by a turbine inlet pressure detector 11, as shown in FIG.
1a is manually powered by a pressure regulator 12, and from this pressure regulator 12, a pressure commensurate with the reactor output,
That is, the steam flow rate request signal 12 corresponding to the reactor thermal output
a is output, and this steam flow rate request signal 12a is input to the steam flow rate control circuit 13 together with the control valve opening signals 3a, 3a' from each control valve 3.3'. As shown in FIG. 1, this steam flow rate control circuit 13 sends an appropriate opening request signal 13a to each control valve 3,3' and bypass valve 7.

13a' and 13b are output to control their opening degrees.

As shown in FIG. 2, the steam flow rate control circuit 13 includes a low value priority circuit 15 into which a steam flow rate request signal 12a from the pressure regulator 12 and a frequency control signal 14a from the system side are input.
Therefore, valve control is normally performed by the steam flow rate request signal 12a from the pressure regulator 12, but when the system frequency fluctuates, the frequency control signal 14a is given priority.

As shown in FIG. 2, the output signal 15a from the low value priority circuit 15 is input to an opening request compensation circuit 16, and from this opening request compensation circuit 16, each control valve 3 .3', opening request signals 13a and 13B' are outputted to control the turbine steam flow rate.

In addition, each control valve opening signal 3a from each control valve 3.3',
3a', as shown in Fig. 2, is manually inputted to the control valve flow rate calculation circuits 17 and 17', and each steam flow rate outputted from each of these control valve flow rate calculation circuits 17 and 17'. The signals 17a, 17a' are sent to the adder 18.
The amount is added manually. Then, the turbine total steam flow rate signal 1 output from this adder 18
8a, as shown in FIG. A bypass valve opening request signal 13b is output as a steam flow rate request signal.

Next, the operation of this embodiment will be explained.

Steam generated in the nuclear reactor 1 is sent to a turbine 4 via a main steam pipe 2 and a plurality of control valves 3,3' to drive a generator 5.

The inlet pressure of the turbine 4 is detected by a turbine inlet pressure detector 11, and its detection signal 11a is transmitted to the pressure regulator 1.
2 is input. As shown in FIG. 2, the steam flow total request signal 12a output from the pressure regulator 12 is input to the low value priority circuit 15 together with the frequency control signal 14a.
The output signal 15a of the low value priority circuit 15 is input to the opening request compensation circuit 16. Then, the opening request compensation circuit 1
From 6 onwards, an opening request signal 13a is sent to each control valve 3.3'.
, 13a' are output, and the turbine steam flow rate is controlled.

On the other hand, the opening signal 3a of each control valve 3, 3'.

As shown in FIG. 2, 3a' is input to each regulator valve flow rate calculation circuit 17, 17', and the flow characteristics of the regulator valves 3, 3' are corrected depending on the number of operating regulator valves 3, 3'. steam flow rate signal 17a.

17a' are output respectively.

These steam flow rate signals 17a, 17a' are input to an adder 18 and added, as shown in FIG.
8 outputs a turbine total steam flow rate signal 18a. This signal 18a is sent to an adder 19 as shown in FIG.
The bypass valve 7 is controlled by the opening request signal 13b which is calculated together with the steam flow rate request signal 12a and the bias signal 20 and output from the adder 19.

Figure 3 is a time characteristic diagram of control valves and bypass valves during system frequency fluctuations, and Figure 4 is a transient response diagram of neutron flux and reactor pressure. show conventional examples.

In the conventional case, the bypass valve opening request signal is the output signal 15a of the low value priority circuit 15 in FIG.
It is controlled by the difference between the steam flow rate request signal 12a and the steam flow rate request signal 12a. Therefore, if the request signal for each valve is rapid, there is a possibility that a mismatch will occur in the response characteristics of the control valve and the bypass valve, and the reactor pressure will increase.

On the other hand, in the case of this embodiment, the bypass valve opening request signal 13b is calculated based on the actual control valve opening, so the mismatch does not occur and Scrum can be avoided.

In addition, conventionally, the opening degree of the adjusting valve was not directly monitored.
If an erroneous closing or opening accident occurs due to a failure of the regulating valve port body, the compensatory action by the bypass valve etc. will be delayed and the possibility of scram etc. will increase.

In contrast, in the case of this embodiment, malfunctions of the regulating valves 3゜3' can be directly detected, and changes in the number of operating regulating valves are taken into account by the respective regulating valve steam flow m calculation circuits 17 and 17'. Since the flow rate of each control valve can be calculated accurately, an appropriate opening request signal 13b can be output to the bypass valve 6.
The risk of scram caused by reactor pressure changes can be avoided.

〔Effect of the invention〕

As explained above, the present invention calculates the bypass valve opening request signal based on the actual control valve opening, so it is possible to effectively avoid scrams caused by changes in reactor pressure, and Health and plant availability can be improved.

[Brief explanation of drawings]

FIG. 1 is an overall configuration diagram showing a nuclear reactor pressure control device according to an embodiment of the present invention, FIG. 2 is a configuration diagram of a steam flow rate control circuit,
FIG. 3 is a time characteristic diagram of the control valve and bypass valve when the system frequency fluctuates, and FIG. 4 is a transient response diagram of neutron flux and reactor pressure. 1...Nuclear reactor, 3.3'...Adjustment valve, 3a, 3a'
... Adjustment valve opening signal, 4... Turbine, 5... Generator, 7... Bypass valve, 11... Turbine inlet pressure detector, 12... Pressure regulator, 12a... - Steam flow rate request signal, 13... Steam flow rate control circuit, 13a,
13B'13b...Opening request signal, 14a...Frequency control signal, 15...Low value priority circuit, 16...Opening request compensation circuit, 17.17'...Adjustment valve flow rate calculation circuit , 17a. 17a'...Steam flow rate signal, 18.19...Adder, 18a...Turbine total steam flow rate signal, 20...Bypass signal.

Claims (1)

[Claims] In a reactor pressure control device that supplies steam generated in a nuclear reactor to a turbine via a plurality of control valves to drive a generator, and also controls the opening degree of a bypass valve to adjust pressure, each of the control valves The control valve steam flow rate calculation circuit calculates the total control valve flow rate based on the valve opening degree of the control valve, and the difference between the output signal from the control valve steam calculation circuit and the signal corresponding to the steam amount sent from the reactor is used to 1. A nuclear reactor pressure control device comprising a steam flow rate control circuit having a bypass valve control circuit that determines the opening degree and flow rate of a bypass valve.