JPS63196912A - Control equipment for nuclear reactor pressure - Google Patents

Abstract

PURPOSE:To control pressure reduction within a certain range of the variation of the reactor water temperature even in a low pressure area by controlling a by-pass valve so that the nuclear reactor pressure corrected with a nonlinear compensating element follows up a calculated target pressure value. CONSTITUTION:When a nuclear reactor pressure P is reduced to reach a rated pressure, a nuclear reactor pressure controller 14 is started. Then, a sampler 15A inputs the pressure P and a reactor water temperature T from a pressure detector 13 and a temperature detector 13 to the controller 14. The temperature T is inputted to a pressure target value calculating means 17 consisting of a function generator 18 and an integrator 19, and this means 17 calculates and outputs a nuclear reactor pressure target value PA. Meanwhile, if the pressure P is lower than the rated pressured, a nonlinear compensating element 16 linearizes the input pressure P because it has a nonlinear characteristic then, and a corrected pressure PC is outputted. Control elements 21 and 22 converts the pressure PC to a valve opening degree request signal (a) and limits it as prescribed and outputs it. A by-pass valve opening controller 23 calculates a valve opening degree target value a' in accordance with the signal (a) and obtains the deviation from an actual valve opening degree b' and outputs a control signal (c) to control a by-pass valve 6, thus controlling pressure reduction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Objective of the Invention (Industrial Application Field) The present invention relates to a reactor pressure control device for controlling reactor pressure in a boiling water nuclear power plant.

(Conventional technology) Conventionally, in order to shut down the reactor of a boiling water nuclear power plant,
First, the main stop valve installed in the main steam piping from the reactor to the turbine is fully closed, and then the reactor pressure control device is used to
It controls the bypass valve installed in the steam pipe that bypasses the turbine and goes from the reactor to the condenser, and sends the main steam from the reactor directly to the condenser, gradually reducing the reactor pressure from the rated pressure. , the reactor was shut down by operating the control rods.

At this time, the reactor pressure vessel is subject to mechanical thermal stress constraints, and rapid changes in reactor water temperature are undesirable.

For this reason, the reactor pressure control system performs pressure reduction control while keeping the rate of change in reactor water temperature within a certain range.

(Problem to be solved by the invention) However, conventional nuclear reactor pressure control equipment uses a Bourdon tube and a differential transformer as a pressure detector to detect reactor pressure, and it is linear near the rated pressure. Since it has a detection characteristic of 10 kg/cdg or less, it has a nonlinear detection characteristic in a low pressure region of 10 kg/cdg or less. For this reason, the reactor pressure in the low pressure region cannot be detected correctly, and pressures below 10 kg/cl g are out of the control range, so depressurization must be controlled manually by operators. However, in the low-pressure region, the amount of operation of the bypass valve is large, and long-term manual operation by operators is a heavy burden, and depressurization control to maintain the rate of change in reactor water temperature within a certain range is problematic. .

Therefore, in the present invention, the reactor pressure is to kg/aJ
It is an object of the present invention to provide a reactor pressure control device that can automatically perform pressure reduction control while keeping the rate of change in reactor water temperature within a certain range even in a low pressure region of less than g.

[Structure of the Invention] (Means for Solving the Problems) The present invention provides a bypass valve opening jack and a pressure detector for detecting the reactor pressure in order to correctly detect the reactor pressure in the low pressure region. A nonlinear compensation element that corrects nonlinear characteristics in the low pressure region to linear characteristics, and a system that inputs the reactor water temperature and calculates the reactor pressure target value at each predetermined time interval from the relationship between the reactor water temperature and saturated steam pressure. Pressure target value′! A bypass valve opening jack is provided to control the bypass valve so that the corrected reactor pressure from the nonlinear compensation element follows the reactor pressure target value calculated by the pressure target value calculation means. It is something.

(Function) Thereby, even in a low pressure region where the reactor pressure is 10 kg/cdg or less, pressure reduction control can be performed while automatically maintaining the rate of change in reactor water temperature within a certain range.

(Embodiment) FIG. 1 shows a system configuration in which a reactor pressure control device according to an embodiment of the present invention is applied to a boiling water nuclear power plant.

Steam from the nuclear reactor 1 passes through a main steam pipe 2, and one side is sent to a steam turbine S directly connected to a generator 4 via a main outlet valve 3. The other part is sent to the condenser 7 via the turbine bypass valve 6. The outlet steam of the steam turbine 5 is sent to the condenser 7
The water is cooled and becomes condensate, which passes through the condensate pipe 8 to the condensate pump 9.
The water is sent to the feed water heater 10 by. The condensate is heated by the feedwater heater 10 and sent to the reactor 1 again by the feedwater pump 11.

On the other hand, the reactor pressure and reactor water temperature inside the nuclear reactor 1 are detected by a pressure detector 12 and a temperature detector 13, respectively. The reactor pressure P from the pressure detector 12 is input to a nonlinear compensation element 16 for correcting the reactor pressure P via a sampler 15A that inputs a signal every sampling period in the reactor pressure control bag [14]. . The reactor water temperature T from the temperature detector 13 is also input to the pressure target value calculation means 17 via the sampler 15A in the reactor pressure control device 14. This pressure target value calculation means 17 includes a function generator 18 for calculating the target pressure change rate F'DtI- from the input reactor water temperature T, and a reactor pressure when the sampler 15A starts sampling, that is, when the control starts. Let P be the initial value.

It consists of an integrator 19 that adds the target pressure change rate PD calculated by the function generator 18 to this at every sampling period and outputs the addition result as the reactor pressure target value PA.

This reactor pressure target value PA and the corrected reactor pressure PC from the nonlinear compensation element 16 described above are input to an adder 20, and the deviations are calculated by A control element 21, B*control element 2
2 and the sampler 15B, which outputs a signal every sampling period in conjunction with the sampler 15A, is output as a valve opening request signal a to the bypass valve control bag W123. Here, the A control element 21 is for converting the deviation from the lfX device 20 into a valve opening request signal a to the bypass valve control device 23, and the 8 control element 22 is for converting the deviation from the lf This is to provide a predetermined limit if the value is not within the range.

Bypass valve control bag! ! The bypass valve opening jack opening setting device 24 in 23 is for inputting the valve opening request signal a from the reactor pressure control 3A 14 and calculating the valve opening target value a' of the bypass valve 6. It is.

The valve opening target value a' calculated by the bypass valve opening jack opening setting device 24 is combined with the actual valve opening b' from the C control element 25 which inputs the valve opening signal of the bypass valve 6. It is input to the adder 26.

The adder 26 is used to calculate the deviation between the input valve opening target value a' and the actual valve opening b', and the deviation is input to the bypass valve opening jack opening controller 27 for control. The signal becomes signal C and is output to the bypass valve 6.

With the above configuration, when the nuclear reactor 1 is normally operated, the bypass valve 6 is closed and the main stop valve 3 is open.

As a result, main steam from the nuclear reactor 1 passes through the main steam pipe 2, passes through the main stop valve 3, drives the steam turbine 5, rotates the generator 4, and obtains a generator output.

When stopping the nuclear reactor 1 from this state, the generator 4 and the system are cut off, the main stop valve 3 is closed, the supply of main steam to the steam turbine 5 is cut off, and the steam turbine 5 is stopped.

Next, the bypass valve 6 is gradually opened using a conventional reactor pressure control device (not shown), and the main steam from the reactor 1 is transferred to the condenser 7.
and keep the rate of change of reactor water temperature T within a certain range (-55℃/
Reduce the pressure to the rated pressure 10kg/c+Jg while maintaining the pressure at 10kg/c+Jg.

Now, when the reactor pressure P becomes 10kg/c+Jg, the reactor pressure control bag! ! 14. Then, the sampler 15^ detects the pressure detector 1 at a predetermined sampling period.
The reactor pressure P from 2 and the reactor water temperature T from the temperature detector 13 are input into the reactor pressure control system.

As shown in FIG. 2, the function generator 18 in the pressure target value calculation means 17 inputs the current reactor water temperature T1, and calculates the reactor water temperature T2 after the sampling period Δ in seconds as T2=T1+ΔtX.
(Target cooling rate). moreover.

Reactor pressures PI and P2 when the reactor water temperature is TI and T2 are determined from the relationship between the reactor water temperature T and the saturation pressure of the reactor 1, and the target pressure change rate PD is calculated using PD=P2-P1. ,
This is output to the integrator 19. Integrator 19 is a reactor pressure control bag! ! 14 is started at time t1 as the initial value, and the input target pressure change rate PD (=
Pz Pt) and convert this to the pressure target value PA (=P
Output as 2).

On the other hand, when the reactor pressure P detected by the pressure detector 12 is less than 10 kg/cjg, the nonlinear compensation element 16 has a nonlinear characteristic and the correct reactor pressure is not detected. Pressure detector 1
The reactor pressure P from 2 is linearized and the corrected reactor pressure PC is output.

Adder 20 outputs the deviation between pressure target value PA from integrator 19 and reactor pressure PC corrected from nonlinear compensation element 16 to A control element 21 . The control element 21 converts this into a valve opening request signal a to the bypass valve 6, while the 8 control element 22 applies a predetermined limit to this and sends it to the sampler 15.
The valve opening request signal a is sent to the bypass valve control device 23 via B.
Output to. Bypass valve opening jack control system! !
! Bypass valve opening jack setting device 2 in 23
4 calculates a target valve opening value a' of the bypass valve 6 based on this valve σ degree requirement compensation code a. The adder 26 inputs this valve opening target value a' and the actual valve opening b' from the C control element 25, and outputs the deviation thereof to the bypass valve opening jack opening controller 27. Based on this, the bypass valve opening jack opening degree controller 27 outputs a control signal C to operate the bypass valve 6, and the bypass valve 6 is removed from the reactor 1.
The main steam sent to condensate II7 is controlled, and the reactor pressure P is reduced from P+ to P2 in Δ seconds.

As a result, the reactor water temperature T determined by the saturated steam pressure after Δ seconds can be set to T2.

Generally, in the n-th sampling period, if the reactor water temperature is Tn, the target reactor water temperature Tn+t after ΔL seconds is Tn * r = Tn+Δ×(target cooling rate), which corresponds to the reactor water temperature jn◆1. Find the reactor pressure Pn++,
Target pressure change rate PDti-PD: Pn+ t-Pn, reactor pressure target value PA is PA-P++ΣPD=Pn+
+ Using the reactor pressure target value PA calculated in this way as a target value, the bypass valve 6 is adjusted by the bypass valve opening jack control device @23, and the nonlinear compensation element 16 is adjusted.
By feedback-controlling the corrected reactor pressure PC from , the reactor water temperature T can be brought to Tn++ after Δ seconds.

As described above, according to this embodiment, in the low pressure region,
It is possible to automatically perform depressurization control of the reactor while keeping the rate of change of the reactor water temperature T within a certain range.

In addition, in this example, depressurization control of 10 kg/c sig or less was explained, but depressurization control from rated pressure to 10 kg/aJ g or less without using any conventional reactor pressure control device can also be performed entirely using this atomic control system. Furnace pressure control bag ffi
! Of course, it is also possible to have 14 perform the process.

[Effect of the invention] As described above, according to the present invention, 10 kg/dg
It is possible to automatically perform depressurization control while maintaining the rate of change in reactor water temperature within a certain range even in the following low pressure regions.
It is possible to obtain a reactor pressure control device that eliminates the long-term depressurization operation by an operator when the reactor is shut down, and contributes to a large rjJ in improving the operating rate of the plant.

[Brief explanation of the drawing]

Fig. 1 is a system configuration diagram in which a reactor pressure control device according to an embodiment of the present invention is applied to a boiling water nuclear power plant;
The figure is an explanatory diagram of characteristic changes in reactor pressure and reactor water temperature during plant shutdown, and FIG. 3 is an explanatory diagram of input/output characteristics of the nonlinear compensation element shown in FIG. 1. 1... Nuclear reactor, 2... Main steam piping, 3... Main stop valve, 4... Generator, 5... Steam turbine, 6... Bypass valve, 7... Condensate Container, 8... Condensate pipe, 9...
Condensate pump, lO... Feed water heater, 11... Water feed pump, 12... Pressure detector, 13... Temperature detector,
14... Reactor pressure control device, 15A, 15b...
sampler. 16... Nonlinear compensation element, 17... Pressure target value calculation means, 18... Function generator, 19... Integrator, 20
．． 26... Adder, 21, 22. 25... Control element, 23... Bypass valve opening jack control device,
24...Bypass valve opening jack opening setting device,
27...Bypass valve opening jack opening controller. Agent Patent Attorney Crest 1) Makoto Figure 1 Figure 2

Claims (1)

[Claims] A nuclear reactor that controls the opening of the bypass valve installed in the steam pipe that bypasses the turbine and goes from the reactor to the condenser, thereby controlling the pressure reduction of the reactor while keeping the rate of change in reactor water temperature within a certain range. The reactor pressure control device includes a pressure target value calculation means for calculating a reactor pressure target value from the detected reactor water temperature, a nonlinear compensation element for correcting the nonlinear characteristics of a pressure detector for detecting the reactor pressure, and and a bypass valve opening jack control device that controls the bypass valve according to the deviation between the reactor pressure value corrected by the nonlinear compensation element and the reactor pressure target value calculated by the pressure target value calculation means. A nuclear reactor pressure control device characterized by: