JPH08327776A - Core control system of boiling water reactor, and core control method - Google Patents

Abstract

PURPOSE: To provide a core control system and method for boiling water reactor which can accurately predict the drift component varying with time, and estimate the stability margin during a transient event, and immediately after the end of the event. CONSTITUTION: Provided are a delay filter 7 which takes in neutron flux signal data of an APRM or an LPRM which are monitoring signals of a boiling water reactor core and predicts drift component, a self-correlater 8 for calculating a self-correlating value sequentially based on the prediction, an stability evaluator 22 for calculating a width reduction ratio based on the self-correlation value and evaluating stability margin of the core, and an indication device 11 for displaying the stability margin in a core monitoring device 24. Further a controlling device 23 is provided with an SPI operator 14 receiving a control rod selection and insertion signal from a judging device 13, an SPI device 15 directing insertion based on the signal, a control rod drive mechanism 16 inserting control rod in the core by the direction, and a flow controller 31 controlling the core flow rate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a boiling water nuclear reactor core control system, and more particularly to a boiling water nuclear reactor core control having a monitoring device suitable for preventing the occurrence of unstable vibrations. The present invention relates to a system and a core control method.

[0002]

2. Description of the Related Art A conventional stability monitoring device for a boiling water reactor is disclosed in Japanese Patent Laid-Open No. 59-79894, which is a neutron flux detector LPRM (Local Power) for a nuclear reactor.
er Range Monitor) is used to determine the pattern of the autocorrelation function of the required frequency component of the neutron flux signal. Here, the autocorrelation function g (t) is defined by the following equation (Equation 3).

[0003]

(Equation 3)

However, φ is the neutron flux signal minus the drift component, t is the delay time, and T is the time.

The function form of the autocorrelation function is such that, when the noise of the input signal is white, f is the frequency,
It can be expressed as the following equation (Equation 4).

[0006]

[Equation 4]

Here, it is understood that a represents the damping constant of the state quantity, and the autocorrelation function is a function of damping vibration.

Conventionally, the stability margin is calculated by using an index called a width reduction ratio, as shown in FIG. 3 and the following equation (Equation 5), and the first peak g (0) of the autocorrelation and the first peak after one cycle. Two peaks g (1 / f)
It is expressed by the ratio of.

[0009]

(Equation 5)

If the width reduction ratio γ> 1, it is unstable. If the width reduction ratio γ <1, it is stable. FIG. 4 shows the result of the plant data of the actual machine by the conventional stability monitoring device. The input signal of the stability monitoring device is the neutron flux signal APRM (Average
Power Range Monitor) is being used. (A) is AP
It is a raw signal of the RM signal. (B) shows the fluctuation component of APRM. This is obtained by subtracting the drift component from the APRM signal in (a). Also, (c) is A in (b)
It shows the autocorrelation value of the fluctuation of the PRM signal,
The autocorrelation value of the neutron flux signal becomes a damped oscillation waveform,
It turns out that it agrees well with the expectation of the expression (3). Therefore, as described above, the width reduction ratio, which is an index of stability, is obtained from the first peak and the second peak of the autocorrelation.

As another method, autocorrelation
When the damping coefficient a and the frequency f are obtained, the reduction ratio can be obtained by the following equation (Equation 6).

[0012]

(Equation 6)

FIG. 5 shows the relationship between the normal operating range and stability. Since the boiling water reactor is designed to be stable in all operating regions, there is no unstable region in the operating region, and it is designed with a margin.

For stability monitoring, low flow rate within the operating range,
It can be seen that the stability margin is minimized on the high output side. Therefore, it can be seen that the monitoring by the stability monitoring device is particularly important in this area.

The operation at low flow rate and high output, which is important to be monitored by the stability monitoring device, can be performed during normal operation, during start-up operation, control rod pattern replacement, or transient event such as pump trip. There is a nature. Therefore, conventionally, the stability is evaluated by design calculation, and the starting operation line and the control rod exchange line are determined in consideration of the margin. For transient events such as pump trips, consider the margin based on the design calculation and determine the operating area of the selected control rod.
It is blocked so as not to enter the operating area where there is little margin of stability.

As shown in FIG. 5, the degree of instability is reduced from point A (width reduction ratio a) (the width reduction ratio is reduced).
As for the direction, a method of decreasing the output by the control rod (SRI) (to the point B) and a method of increasing the flow rate (to the point C)
There is a method (to point D) in which both are combined.

[0017]

However, in the prior art, since the operation line is conservatively determined based on the design calculation, there is a large margin of stability, and much time is required for startup, control rod pattern replacement, etc. There was a problem.

In a transient event such as a pump trip, the neutron flux signal changes abruptly. Therefore, in the conventional stability monitoring device, the stability is evaluated by processing the fluctuation amount of the signal. There was a concern of making an erroneous evaluation because it cannot follow changes.

FIG. 6 shows the results obtained by the stability monitoring device immediately before and after the pump trip. (A) is the raw signal value of the APRM signal, (b) is the one with the drift component removed,
(C) shows the result of the reduction ratio. It can be seen that the pump was rated before the trip, and the reduction ratio was small and stable.
When a pump trip occurs, the flow rate is reduced and the output is reduced rapidly. As a result, the neutron flux signal APRM also sharply decreases. However, since the current filter (drift component removal) cannot follow the drift component prediction with this sudden transient event, a large drift component due to a time delay remains as shown in (b), and as a result, the state stabilizes. The reduction ratio displays an unreliable value until the prediction of the drift component by the filter catches up. That is, it is understood that the stability index, that is, the width reduction ratio cannot be displayed for about 50 seconds after the occurrence of the transient event.

In other words, the conventional stability monitoring device has a problem that the stability margin cannot be accurately estimated because the drift component changes rapidly immediately after the transient event.

An object of the present invention is to make it possible to accurately predict a drift component that changes from time to time even when a transient event such as a pump trip occurs, and to estimate the stability margin during and immediately after the transient event. An object of the present invention is to provide a water reactor core control system and core control method.

[0022]

In order to achieve the above object, the present invention provides a monitoring signal A for a boiling water reactor core.
A core monitoring device that evaluates and monitors the stability margin of the core using PRM or neutron flux signal data of LPRM, a determination device that determines the stability margin, and controls the operation of the core based on the determination result. In a boiling water reactor core control system having a control device, the core monitoring device is a delay filter that predicts a drift component by capturing the neutron flux signal data, and an autocorrelation value is sequentially obtained based on the prediction. It is characterized by comprising an autocorrelator to be obtained and a stability evaluator which calculates a reduction ratio based on the autocorrelation value and evaluates the stability margin of the core.

Another feature of the present invention is that while monitoring and monitoring the stability margin of the core by using neutron flux signal data of APRM or LPRM which is a monitoring signal of the boiling water reactor core, Stability margin is determined, in the boiling water reactor core control method for controlling the operation of the core based on the determination result, the drift component is predicted by incorporating the neutron flux signal data into the delay filter, based on the prediction Sequentially obtain the autocorrelation value, by calculating the reduction ratio based on the autocorrelation value to evaluate the stability margin of the core, to determine the stability margin while monitoring the core, the determination As a result, the control rod selection insertion signal is received, the control rod insertion is instructed based on the signal, and the control rod is inserted into the core to control the operation of the core.

Further, another feature of the present invention is that the stability margin of the reactor core is evaluated and monitored by using the neutron flux signal data of APRM or LPRM which is the monitoring signal of the boiling water reactor core. Stability margin is determined, in the boiling water reactor core control method for controlling the operation of the core based on the determination result, the drift component is predicted by incorporating the neutron flux signal data into the delay filter, based on the prediction Sequentially obtain the autocorrelation value, by calculating the reduction ratio based on the autocorrelation value to evaluate the stability margin of the core, to determine the stability margin while monitoring the core, the determination As a result, a core flow rate adjustment signal is received, a pump rotation speed change signal is transmitted to the pump system based on the signal, and the pump rotation speed is changed to adjust the core flow rate. The Rukoto is to control the operation of the reactor core.

[0025]

According to the present invention, since the delay filter responds to the abrupt change of the drift component, the time series data before and after the time T1 is used, and the time τ past the time T0 at which the data is captured is τ. The drift component is predicted at T1 (= T0-τ).

In the drift component removal filter used in the conventional online stability monitoring device, as shown in FIG. 7, the drift component yi at the time T0 when the data is captured is predicted, and the original signal si is used. By subtracting this drift component yi, the fluctuation component xi of the APRM signal is evaluated. For the prediction of the drift component yi, an arithmetic mean or a filter of first-order lag, which is expressed by the following equations (7) and (8), is used.

Example 1 (arithmetic mean value of xi)

[0028]

(Equation 7)

Example 2 (first-order lag filter)

[0030]

(Equation 8)

(Here, C is a coefficient depending on the cut frequency, but C = 0.95 when the cut time is several seconds and the cut frequency is several Hz.) The conventional method is generalized and summarized as follows. It is reduced to an equation like (Equation 9).

[0032]

[Equation 9]

In other words, the drift component at time T0 is extrapolated and estimated from the data past time T0. Therefore, when xi changes greatly, the weight of the past data is larger than T0, so that time T
There is a problem that the weight of the data past 0 is added and the change of xi cannot be followed. Therefore, when the drift component at the time T0 between them is interpolated from the data before the time T0 and the data after the time T0, the load of the data is dispersed, so that the prediction reliability can be improved. This method is the basic principle of the present invention. Therefore, the prediction of the drift component is evaluated with a slight delay from the time T0 when the data is captured, and the stability is also delayed by the same time. However, the delay time is about several seconds, and there is no problem in monitoring the stability. Further, the drift margin prediction follows even during a sudden transition, so that the stability margin can be displayed.

Further, the general form of the drift component prediction is as in the following formula (Equation 10), but as an example, the drift component prediction by the fit formula of the least square method will be explained.

[0035]

[Equation 10]

The fitting formula by the least squares method is also included in the above general formula, and the drift component can be accurately predicted. FIG.
Shows an example of data processing immediately after the transient event. The left end of the data is the time T0 when the data is taken in, but the value at the left end (time T0) of the least-squares fit expression is the same as that of the conventional technique, and thus a large difference occurs. However, τ from the time T0 when the data is acquired
It can be seen that the drift component can be accurately predicted at time T1 (T1 = T0-τ) delayed by a second (about 2 wavelengths, about 4 seconds).

Therefore, by using the delay filter defined in (Equation 10), even for a sudden transient event,
The stability margin can always be evaluated.

Next, the examination result of the delay time τ of the delay filter will be described. FIG. 9 shows the calculation result immediately after the transient event when the delay time τ of the delay filter is used as a parameter. The horizontal axis of the figure is a dimensionless product obtained by multiplying the delay time τ by the fundamental frequency f of the neutron flux signal, and the vertical axis shows the reduction ratio of the stability index. As is clear from FIG. 9, τ = 0
It can be seen that the accuracy becomes worse at the time of, but the value of the reduction ratio approaches a constant value as τ becomes larger. That is, from the viewpoint of improving the prediction accuracy of the width reduction ratio, τ is the reciprocal 1 of the fundamental frequency.
It is understood that it is necessary to secure at least / f.

FIG. 10 shows the result of applying the present invention to a pump trip event as a transient event.
(A) shows the raw signal value of the APRM signal, (b) shows the APRM fluctuation value with the drift component removed, and (c) shows the value of the reduction ratio of the stability index. As is clear from FIG. 10, in the core monitoring device of the present invention with respect to a sudden change in pump trip, since the drift component is accurately predicted, the fluctuation component of the neutron flux in (b) can be accurately evaluated, As a result, the decrement ratio can be evaluated with high accuracy both during the occurrence of the transient event and after the end of the transient event. However, although the result at the time T1 (past time) delayed by several seconds with respect to the time T0 at which the data is fetched is evaluated, the delay time is also several seconds, and it cannot be displayed for 50 seconds in the conventional example. There is no problem in stability evaluation even when compared with.

Thus, even for a sudden transient event,
The drift component that changes from time to time can be accurately predicted, and the stability margin can be estimated during the transient event and immediately after the event.
The stability margin can always be evaluated.

[0041]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A boiling water reactor core control system and core control method according to an embodiment of the present invention will be described below with reference to the drawings.

1 and 2 show a first embodiment according to the present invention. FIG. 1 shows the entire configuration of a boiling water reactor core control system, and FIG. 2 shows the details of the configuration of a core monitoring device provided in the boiling water reactor core control system.

The core monitoring device 24 evaluates the stability of the BWR and the delay filter 7 for predicting the drift component by taking in the neutron flux signal data of the APRM 21 and LPRM 20 which are the monitoring signals of the boiling water reactor core. The auto-correlator 8, the stability evaluator 22 including the frequency evaluator 9 and the width reduction ratio evaluator 10, and the display device 11 for displaying the stability margin.

The delay filter 7 is composed of a delay register 1, a multiplier 2 and an adder 3, and with respect to the input signal Xn,
The relationship of Expression (10) is satisfied. When the expression (10) is satisfied, the signal to be evaluated is Xn-D past the input signal Xn by the delay time D. X in the equation (10)
And a linear expression of Y, the following expression (Equation 11) is obtained.

[0045]

[Equation 11]

It becomes

The input signal is the X signal from the delay register 1.
It is stored as i, Xi-1, Xi-2, ..., Xk.
This stored signal is output by the multiplier 2 to ai · Xi, b.
i · Yi, Σai · Xi, Σbi · Yi by the adder 3
Signal. The drift component Yn-D is calculated from Σai · Xi and Σbi · Yi. This drift component Y
By reversing the sign of n-D and adding it to Xn-D by the adder, only the fluctuation component of the input signal becomes a signal.

The autocorrelator 8 is composed of a multiplier 5, an integrator 6 and a delay device 4. The computing means composed of the multiplier 5 and the integrator 6 outputs the autocorrelation value g (0) with a delay time of 0 seconds in response to the input signal to the autocorrelator 8. Further, the calculation means composed of the multiplier 5, the integrator 6 and the delay device 4 respectively have delay times Δt, 2Δt,
..., the autocorrelation value of nΔt seconds g (Δt), g (2Δt),
,, g (nΔt) is output.

This output is input to the frequency evaluator 9 of the stability evaluator 22, and after evaluation of the frequency f and the attenuation coefficient a,
The reduction ratio evaluator 10 calculates the reduction ratio. The calculated reduction ratio is visualized by the display device 11.

As described above, the core monitoring device 24 can accurately predict a drift component that changes from moment to moment even in a transient event, and can accurately monitor the stability margin during the transient event after the event settling. Become.

Further, even in the steady state, when the determination device 13 determines that the stability margin has decreased, the control device 23 includes a series of SRI for inserting the control rod, a jet pump, an internal pump, etc. Flow rate adjusting device 31 for controlling the pump system 30 for ensuring the core flow rate
Therefore, the stability margin can be secured.

The control device 23 receives the selected control rod insertion signal from the determination device 13 and selects an SRI (Selected Rod Inserti).
on) Actuating device 14 and SR for instructing insertion based on a signal
I device 15, a control rod drive mechanism 16 for inserting a control rod into the core according to an instruction, and a determination device 13 receive a core flow rate adjustment signal, and send a pump rotation speed change signal to the pump system 30 to change the pump rotation speed. Is configured by a flow rate adjusting device 31 for adjusting the flow rate of the core by changing

FIG. 11 shows a second embodiment according to the present invention. In this embodiment, the reactor is started by using the core monitoring device 24. In a nuclear reactor which does not use the core monitoring device 24 of the present invention, (a) and (b) of FIG.
As shown in, it is necessary to avoid the stability limit curve that is conservatively set in advance by the core heat output and the core flow rate and perform the startup. In this embodiment, since the stability margin can be directly monitored in real time, if the stability margin is large without taking an excessive margin in the stability limit curve set conservatively, the stability margin shown in FIG. As shown in (c), it is possible to start the vehicle slightly beyond the stability limit curve. This makes it possible to simplify the startup operation and shorten the startup time.

FIG. 12 shows a third embodiment according to the present invention. In this embodiment, the control rod pattern of the nuclear reactor is exchanged by using the core monitoring device 24. In a nuclear reactor that does not use the core monitoring device 24 of the present invention, as shown in FIGS. 12 (a) and 12 (b), a stability limiting curve that is conservatively set in advance by the core heat output and the core flow rate is used. It is necessary to avoid it and replace the control rod pattern. In the present embodiment, since the stability margin can be directly monitored in real time, if the stability margin is large without taking an excessive margin in the stability limit curve that is set conservatively, (( As shown in c), a control rod pattern exchange that slightly exceeds the stability limit curve can be performed. As a result, the control rod pattern exchange operation can be simplified and the control rod pattern exchange time can be shortened.

FIG. 13 shows a fourth embodiment according to the present invention. The reactor core control system according to the present embodiment includes a core monitoring device 24, a stability mode determiner 17, an instability occurrence position determiner 18, an unstable occurrence region determiner 19, and a controller 23. There is. The core monitoring device 24 is composed of a delay filter 7, an autocorrelator 8, a stability evaluator 22 and one display device arranged in parallel.

In the present embodiment, when the stability margin decreases, the stability mode determiner 17 determines the stability mode (all core unstable mode, region unstable mode, channel unstable mode). It guides appropriate stability measures. For the stability mode determined by the stability mode determiner 17 from the signals of the LPRM20 and the APRM21, the control rods are evenly inserted into the core so as to reduce the output of the entire core for the all core unstable mode. , Insert the control rod into the region where the stability margin is small for the region unstable mode, and insert the control rod adjacent to the channel where the stability margin is small for the channel unstable mode. Is to do.

Further, according to the present embodiment, when the stability margin decreases, an appropriate control rod can be inserted, and excessive control rod insertion is performed in order to secure the stability margin. Will disappear. As a result, it becomes possible to simplify the recovery operation from the time when the stability margin after the control rod is inserted and to shorten the recovery time.

FIG. 14 shows a fifth embodiment according to the present invention. The core monitoring device 24 of the present embodiment includes the delay filter 7,
Auto-correlator 8, frequency evaluator 9, integration range evaluator 12,
The reduction ratio evaluator 10 and the display device 11 are included. Also,
The operating principle of this embodiment is basically the same as that of the embodiment of FIG. 1, but the number of signal data used for defining the drift component in the delay register 1 is calculated by the frequency evaluator 9. Determined using frequency f.
This defines the number of data (integration range) for performing Σ in the equation (10), and is defined by the number of data corresponding to the time of several wavelengths from the frequency f. The drift component defined by the data in such a range can be accurately obtained, and the range of the data to be evaluated is limited, so that the processing time can be shortened.

FIG. 15 shows a sixth embodiment according to the present invention. The nuclear reactor core control system according to the present embodiment includes a reactor core monitoring device 24, a determination device 13, and a control device 23. The core monitoring device 24 is composed of a delay filter 7, an autocorrelator 8, a frequency evaluator 9, an integration range evaluator 12, a reduction ratio evaluator 10, and a display device 11.

The principle of operation up to the calculation of the width reduction ratio in this embodiment is the same as that of the embodiment of FIG. 1, but in the present embodiment, the calculated width reduction ratio is compared with the reference value by the judging device 13, When it is determined that the stability margin is small, the SR of the control device 23
Send a signal to the I-actuator 14. When a signal is sent to the SRI actuating device 14, a signal for SRI actuation is sent to the SRI device 15, and the control rod driving mechanism 16 inserts the control rod according to a predetermined control rod pattern. When the control rod is inserted, the output decreases, which restores the stability margin. Further, by using the signal processing method of the present embodiment, the reliability of the SRI actuation signal itself is increased.

FIG. 16 shows a seventh embodiment according to the present invention. It is an example of simultaneously displaying and monitoring the conventional processing method and the processing method of the present invention. When the processing method of the present invention is used, the processing can be performed with high accuracy, but the processing involves a delay time. As shown in (a), since the conventional processing method has a quick response, the calculated reduction ratio is displayed as a predicted value,
Further, as shown in (b), the processing method of the present invention displays the calculated reduction ratio as a fixed value. By displaying in this way, the stability margin can be accurately monitored, and the stability margin non-monitoring time associated with the delay time can be roughly understood as a predicted value to improve the reliability of stability margin monitoring. can do.

FIG. 17 shows an eighth embodiment according to the present invention. The present embodiment is an example in which the conventional filter processing method and the filter processing method of the present invention are combined. In this method, a process using the conventional method is displayed as a predicted value, and a process using the method of the present invention is displayed as a fixed value. Although the processing using the method of the present invention can be processed with high accuracy, the width reduction ratio cannot be calculated during the delay time.
The value of the conventional method is displayed as the predicted value, and after the delay time, the value calculated using the method of the present invention is displayed as the fixed value. According to the present embodiment, the stability margin can be accurately monitored, and the stability margin non-monitoring time associated with the delay time can be roughly grasped as a predicted value to improve the reliability of the stability margin monitoring. it can.

FIG. 18 shows a ninth embodiment according to the present invention. Conventionally, the determination of the occurrence of a transient event is based on the amount of change in the absolute value of the neutron flux, so there is a concern that it will take time before the level of change in the neutron flux reaches a certain set value. In this embodiment, the delay filter 7 and the signal converter 2 are used.
8. In the core monitoring device 24 including the autocorrelator 8, the stability evaluator 22, and the display device 11, whether or not a drastic drift change occurs at the time T1 τ seconds past on the downstream side of the delay filter 7. A drift determiner 27 for determining
The downstream side of the drift determiner 27 is a selection control rod drive mechanism 29.
Alternatively, it is configured to be connected to an alarm device.

With this configuration, when the drift component changes abruptly, the selective control rod drive mechanism 29 or the alarm device can be activated with a delay of only the delay time of the delay filter 7. The delay time of the delay filter 7 is
It is about one cycle of the natural vibration mode of the neutron flux. Since the cycle of the natural vibration mode of the neutron flux is about 2 seconds, the occurrence of a transient event can be determined in about 2 seconds. Therefore, the operation of the selection control rod and the alarm are issued at an early stage while maintaining a sufficient margin, which further increases the safety margin.

FIG. 19 shows a tenth embodiment of the present invention. In this embodiment, the delay filter 7 and the signal converter 2 are used.
8. In the core monitoring device 24 including the autocorrelator 8, the stability evaluator 22, and the display device 11, between the delay filter 7 and the autocorrelator 8, there is a rapid drift change at time T1 τ seconds past. It is provided with a drift determiner 27 for determining whether or not, and a signal converter 28 for replacing the drift component with the current signal component when the drift component changes rapidly and regarding the signal processing component as zero. With this configuration, the drift component can follow any high-speed transient event, so that the accuracy is not reduced due to the delay in drift component prediction.

[0066]

According to the present invention, the stability margin can be monitored and the operation can be controlled even in an event that is important for stability, and its reliability can be improved.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a boiling water reactor core control system according to an embodiment of the present invention.

FIG. 2 is a detailed view of the configuration of a core monitoring device provided in the boiling water reactor core control system of FIG.

FIG. 3 is a diagram showing an autocorrelation value.

FIG. 4 is a diagram showing an evaluation result of an actual machine by a conventional stability monitoring device.

FIG. 5 is a diagram showing a relationship between an operating region and stability.

FIG. 6 is a diagram showing an evaluation result at the time of pump trip by a conventional stability monitoring device.

FIG. 7 is a diagram showing a result of a conventional drift component prediction method.

FIG. 8 is a diagram showing a drift component prediction result at the time of pump trip by the method of the present invention.

FIG. 9 is a diagram showing a sensitivity analysis of delay time of a delay filter.

FIG. 10 is a diagram showing an evaluation result at the time of pump trip according to the method of the present invention.

FIG. 11 is a diagram showing a second embodiment in which the reactor is started up using a core monitoring device.

FIG. 12 is a diagram showing a third embodiment in which the control rod pattern of the nuclear reactor is exchanged using a core monitoring device.

FIG. 13 is a diagram showing a fourth embodiment according to the present invention.

FIG. 14 is a diagram showing a fifth embodiment according to the present invention.

FIG. 15 is a diagram showing a sixth embodiment in which the present invention and SRI are combined.

FIG. 16 is a diagram showing a seventh embodiment for simultaneously displaying and monitoring the conventional processing method and the processing method of the present invention.

FIG. 17 is a diagram showing an eighth embodiment in which the conventional filter processing method and the filter processing method of the present invention are combined.

FIG. 18 is a diagram showing a ninth embodiment according to the present invention.

FIG. 19 is a diagram showing a tenth embodiment according to the present invention.

[Explanation of symbols]

1 ... Delay register, 2, 5 ... Multiplier, 3 ... Adder, 4 ...
Delay device, 6 ... Integrator, 7 ... Delay filter, 8 ... Autocorrelator, 9 ... Frequency evaluator, 10 ... Reduction ratio evaluator, 11 ...
Display device, 12 ... Integration range evaluator, 13 ... Judgment device, 1
4 ... SRI actuating device, 15 ... SRI device, 16 ... control rod drive mechanism, 17 ... stability mode determiner, 18 ... unstable occurrence position discriminator, 19 ... unstable occurrence region discriminator, 20 ... L
PRM, 21 ... APRM, 22 ... Stability evaluator, 23 ...
Control device, 24 ... Core monitoring device, 25 ... Sign reversal device, 2
7 ... Drift judgment device, 28 ... Signal converter, 29 ... Selection control rod drive device, 30 ... Pump system, 31 ... Flow control device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hideo Soneda 3-1-1, Saiwai-cho, Hitachi-shi, Ibaraki Hitachi Ltd. Hitachi factory (72) Inventor Hidetaka Sakamoto 3-chome, Saiwai-cho, Hitachi, Ibaraki No. 1 Stock company Hitachi Ltd. Hitachi factory (72) Inventor Takanori Fukahori 32-1 No. 2 Sachimachi, Hitachi City, Ibaraki Hitachi Engineering Co., Ltd.

Claims (16)

[Claims] 1. An AP which is a supervisory signal for a boiling water reactor core.
A core monitoring device that evaluates and monitors the stability margin of the core by using neutron flux signal data of RM or LPRM, a determination device that determines the stability margin, and controls the operation of the core based on the determination result. In a boiling water reactor core control system having a control device, the core monitoring device is a delay filter that predicts a drift component by capturing the neutron flux signal data, and an autocorrelation value is sequentially obtained based on the prediction. The desired autocorrelator,
A boiling water reactor core control system, comprising a stability evaluator that calculates a reduction ratio based on the autocorrelation value and evaluates a stability margin of the core. 2. The delay filter according to claim 1, wherein the delay filter has a time T1 (T1 = T0) τ seconds past the present time T0.
-Τ) is used to predict the drift component, and the fluctuation amount of the neutron flux signal is evaluated by subtracting the drift component from the neutron flux signal at the time T1 in the past τ seconds. Reactor core control system. 3. The τ according to claim 1 or 2, wherein the delay filter has a reciprocal time 1 / f or more of the fundamental frequency of the fluctuation of the neutron flux signal. Boiling water reactor core control system. 4. The boiling water reactor core control system according to claim 1, wherein drift component prediction of the neutron flux signal in the delay filter is performed by the following equation (Equation 1). . [Equation 1] Here, Yk; drift component value of neutron flux signal at time Tk, Xi; neutron flux signal data value at time Ti, ai; coefficient, bi; coefficient. However, if 1 <k <m, and the interval of the neutron flux signal data is Δt, then (k−m) = τ / Δt. 5. The control device according to claim 1, wherein the control device receives an SRI actuation device for receiving a selection control rod insertion signal from the determination device, an SRI device for instructing insertion based on the signal, and an SRI device for instructing insertion to the core according to the instruction. A boiling water reactor core control system comprising a control rod drive mechanism for inserting the control rod. 6. The control device according to claim 1, wherein the control device receives a core flow rate adjustment signal from the determination device, and transmits a pump rotation speed change signal to a pump system based on the signal to change the pump rotation speed. And a flow rate adjusting device for adjusting the flow rate of the reactor core. 7. The boiling water reactor core control according to claim 1, wherein the control device controls the operation of the reactor core when the judging device judges that the stability margin is small. system. 8. The boiling water reactor core control system according to claim 1, wherein the control device controls the operation of the reactor core when the reactor is started. 9. The boiling water reactor core control system according to claim 1, wherein the control device controls the operation of the core when the control rod pattern is replaced. 10. The stability mode determiner according to claim 1, wherein the stability mode determiner discriminates a plurality of unstable modes in which the stability margin is reduced, and a stability mode determiner is provided for each of the identified unstable modes. The controller controls the operation of the reactor core, respectively, and the boiling water reactor core control system is characterized. 11. The core monitoring device according to claim 1, wherein the core monitoring device delays the neutron flux signal in addition to displaying a stability margin at time T1 τ seconds past based on the delay filter. A boiling water reactor core control system characterized in that a system is provided directly to the autocorrelator and the stability evaluator without passing through a filter, and an expected value at time T0 based on the system is also displayed at the same time. 12. A supervisory signal for a boiling water reactor core
A boiling water reactor for determining the stability margin while evaluating and monitoring the stability margin of the core by using neutron flux signal data of PRM or LPRM, and controlling the operation of the core based on the determination result. In the core control method, the neutron flux signal data is taken into the delay filter to predict the drift component, the autocorrelation value is sequentially obtained based on the prediction, and the decrement ratio is calculated based on the autocorrelation value to By evaluating the stability margin of the core, to determine the stability margin while monitoring the core, depending on the determination result, receiving a selection control rod insertion signal, instructing the control rod insertion based on the signal, A boiling water reactor core control method comprising controlling the operation of the core by inserting the core into the core. 13. A supervisory signal for a boiling water reactor core
A boiling water reactor for determining the stability margin while evaluating and monitoring the stability margin of the core using neutron flux signal data of PRM or LPRM, and controlling the operation of the core based on the determination result. In the core control method, the drift component is predicted by incorporating the neutron flux signal data into the delay filter, the autocorrelation value is obtained sequentially based on the prediction, and the width reduction ratio is calculated based on the autocorrelation value. By evaluating the stability margin of the core, the stability margin is determined while monitoring the core, the core flow rate adjustment signal is received according to the determination result, and a signal indicating a change in pump speed to the pump system based on the signal. To control the operation of the core by changing the pump rotation speed to adjust the flow rate of the core. Way. 14. The method according to claim 12 or 13,
The delay filter predicts the drift component at time T1 (T1 = T0−τ) τ seconds past the current time T0,
A boiling water reactor core control method, characterized in that the fluctuation amount of the neutron flux signal is evaluated by subtracting the drift component from the neutron flux signal at time T1 in the past τ seconds. 15. The method according to any one of claims 12 to 14,
Τ in the delay filter (time to go back to the past)
Is set to the reciprocal number 1 / f or more of the fundamental frequency of the fluctuation of the neutron flux signal, and a boiling water reactor core control method. 16. The method according to claim 12 to claim 15,
A boiling water reactor core control method, wherein the drift component prediction of the neutron flux signal in the delay filter is performed by the following equation (Equation 2). [Equation 2] Here, Yk; drift component value of neutron flux signal at time Tk, Xi; neutron flux signal data value at time Ti, ai; coefficient, bi; coefficient. However, if 1 <k <m, and the interval of the neutron flux signal data is Δt, then (k−m) = τ / Δt.