JPH04115190A - Controlling apparatus for output of reactor - Google Patents

Abstract

PURPOSE:To stabilize a control of an output of a reactor by providing a monitoring element determining the stability on the basis of inputs of a neutron flux level, a neutron flux level change rate and a control rod position signal, a fuzzy control element and a constraint fuzzy control element. CONSTITUTION:A reactor output control apparatus 23 comprises a monitoring element 23a, a predictive fuzzy control element 23b and a constraint fuzzy control element 23c. The monitoring element 23a judges the stability of a reactor from inputs of a neutron flux level N, a neutron flux change rate DN and a control rod position Z. A neutron flux level Nn and a control rod position Zn obtained through this judgement are given to the control element 23b. Receiving the level Nn and the position Zn from the monitoring element 23a as inputs, the control element 23b sets a control rod position instruction Zi and a speed Vr of insertion and withdrawal of a control rod by fuzzy inference. This instruction Zi is given to a control rod driving mechanism 14 and the speed Vr to the control element 23c respectively. The control element 23c corrects the speed Vr as a process amount around the reactor by the fuzzy inference on the basis of an input of the change rate DN, for instance, and a control rod drive instruction Vi obtained as the result is given to the control rod driving mechanism 14.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a nuclear reactor power control device, and particularly to a nuclear reactor power control device that controls the criticality of a nuclear reactor by manipulating the position of control rods. Regarding equipment.

(Conventional technology) About conventional reactor power control equipment! This will be explained with reference to FIG.

A nuclear reactor 1 houses a reactor core 1a, which generates heat due to a nuclear fission chain reaction and heats a primary coolant flowing within the reactor. The heated primary coolant is sent to the intermediate heat exchanger 3 via the high temperature side pipe 2, and transfers heat to the primary coolant through heat exchange. The primary coolant whose temperature has been lowered by heat exchange is returned to the reactor 1 through the low temperature side pipe 4. Such circulation of the primary coolant is performed by a circulation pump 5 interposed in the low temperature side piping 4.

On the other hand, the secondary coolant that has undergone heat exchange in the intermediate heat exchanger 3 is sent through the high-temperature side pipe 6 to the steam generator 7, which is a load heat exchanger. Here, a case will be described in which the steam generator 7 is used as an example of a load heat exchanger, but an air cooler and other cooling systems have a similar cooling system configuration. The secondary coolant whose temperature has been lowered by heat exchange in the steam generator 7 is returned to the intermediate heat exchanger 3 through the low temperature side pipe 8. Such circulation of the secondary coolant is performed by a circulation pump 9 interposed in the low temperature side piping 8.

The control of the nuclear reactor is based on the output setting value from the output setting device 10,
This is performed by the reactor power control device 13 using the reactor exit temperature from the temperature detector 11 and the neutron flux level from the neutron detector 12. The reactor power control device 13 uses the reactor outlet temperature from the temperature detector 11 as a feedback signal, processes the neutron flux level from the neutron detector 12 as an auxiliary signal, and generates a control rod drive speed command signal obtained as a result. is output to the control rod drive mechanism 14. The control rod drive mechanism 14 that receives the control rod drive speed command signal adjusts the reactor output by inserting and removing the control rods 15 into and from the reactor core 1a.

(Problems to be Solved by the Invention) In the conventional reactor power control device 13, during low power operation,
Especially in the critical state, the response of the neutron flux level to the control rod operation is highly nonlinear, making it difficult to automatically control the reactor to the critical state. For this reason, during operation up to criticality, the operator manually operated the control rods 15. However, there was a problem in that the details of the operation depended on the experience and skill of the operator.

The present invention has been made in consideration of the above circumstances, and it is an object of the present invention to provide a nuclear reactor power control device that can automatically and stably control the reactor power from a reactor shutdown state to criticality.

[Structure of the invention]

(Means for Solving the Problem) As a means for achieving the above object, the present invention provides a nuclear reactor power control device that controls the output of a nuclear reactor by giving a control rod drive speed command signal to a control rod drive mechanism. A monitoring unit that determines stability by inputting the flux level, neutron flux level change rate, and control rod position signal, and a monitoring unit that determines stability by inputting the neutron flux level and control rod position signal when it is determined that the monitoring unit is stable. , a predictive fuzzy control unit that predicts the control rod position at critical times in the reactor and sets the position and speed of control rod withdrawal or insertion using fuzzy reasoning, and various process variables related to the reactor, such as the rate of change in neutron flux level. and a constraint fuzzy control section that corrects the control rod withdrawal or insertion speed set by the predictive fuzzy control section by fuzzy reasoning based on the input of the above.

(Function) In the reactor power control device according to the present invention, after the monitoring unit confirms the stability of the reactor, the predictive fuzzy control unit
Based on the neutron flux level and control rod position signal when the reactor stability is confirmed by the monitoring unit, the control rod position at criticality is predicted by comparing the reciprocal of the neutron flux level with the control rod position, and the fuzzy Inference sets the position and speed of control rod withdrawal or insertion. Thereafter, the constraint fuzzy control unit corrects the control rod withdrawal or insertion speed set by the predictive fuzzy control unit based on the input of various process variables related to the reactor, such as the rate of change in neutron flux level, and corrects the control rod position. Outputs a command signal and a control rod drive speed command signal to the control rod drive mechanism. Therefore, it is possible to stably and automatically control the reactor output from the reactor shutdown state to criticality.

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

FIG. 2 shows an example of a nuclear reactor power control device according to the present invention, and in the figure, reference numeral 1 indicates a nuclear reactor.
The reactor core 1a is housed in the reactor core 1a, and the control rods 1 are installed in the reactor core 1a.
5 is provided so that it can be inserted and removed by a control rod drive mechanism 14. Further, a control rod position detector 20 that measures the position of the control rod 15 is installed in the control rod drive mechanism 14, and a control rod position signal from this control rod position detector 20 is transmitted to the reactor power control system. 23.

This reactor power control device 23 also includes a power setting device 10.
The output setting value from the reactor 1, the neutron flux level from the neutron detector 12 disposed around the reactor 1, and the rate of change in the neutron flux level from the differentiator 21 which takes this neutron flux level as input are respectively input. It has become. The reactor power control device 23 performs arithmetic processing based on the neutron flux level, neutron flux level change rate, and control rod position signal,
A control rod position command signal and a control rod drive speed command signal are given to the control rod drive mechanism 14 to control the reactor output.

This reactor power control device 23, as shown in FIG.
It is composed of a monitoring section 23a, a predictive fuzzy control section 23b, and a constraint fuzzy control section 23c.

The monitoring unit 23a determines the stability of the reactor by inputting the neutron flux level N, the neutron flux level change rate DN, and the control rod position Z. The neutron flux level N and control rod position Z are provided to the predictive fancy control section 23b.

The predictive fuzzy control unit 23b receives the neutron flux level N and control rod position Z from the monitoring unit 23a as n inputs, and sets the control rod position command Z and the insertion/extraction speed V of the control rod 15 by fuzzy reasoning. It has become. Then, the control rod position command Z is sent to the control side rod drive mechanism 14, and the insertion/extraction speed V is given to the control rod drive mechanism 14, and the insertion/extraction speed V is given to the control rod drive mechanism 14.
The control unit 23c is provided with the respective signals.

The constraint fuzzy control unit 23c corrects the insertion/removal speed ■ by fuzzy reasoning by inputting, for example, the neutron flux level change rate DN as various process quantities around the reactor, and the control rod The drive speed command V is given to the control rod drive mechanism 14.

Next, the operation of this embodiment will be explained.

First, the processing in the monitoring section 23a will be explained with reference to the flowchart shown in FIG.

In step S31, the control rod position Z and the neutron flux level change rate DN are read, and the control rod position change rate DZ is calculated. Next, in step S32, the absolute values of each of the neutron flux level change rate DN and the control rod position change rate DZ are set to a sufficiently small value ε. , ε2. Then, each absolute value of the neutron flux level change rate DN and the control rod position change rate DZ is a sufficiently small value ε.

If it is smaller than ε2, in step 533,
The neutron flux level N is read and set as N 2 and outputted to the predictive fuzzy control section 23b, and the control rod position at that time is set as Z 2 and outputted to the predictive fuzzy system side section 23b.

Next, the process in the predictive fuzzy control unit 23b is
This will be explained with reference to the flowchart shown in the figure.

First, in step S41, the neutron flux level N and control rod position Zn are read from the monitoring section 23a. Subsequently, in step S42, the neutron flux level N and control rod position Z are input from the monitoring unit 23a. -1, the predicted critical control rod position Z is determined by equation (1) shown below.
Calculate.

Next, in step 543, the deviation Z between the predicted critical control rod position Z 1 and the control rod position Z 2 is determined.

Calculate CQ Zo (positional deviation) and substitute the deviation into the membership function shown in Figure 5 to obtain positive and large (P B) grade, positive and small (P S) grade, and zero (ZO).
Determine the grade, negative less (NS) grade, and negative greater (NB) grade.

Next, in step S44, a deviation N between a preset criticality neutron flux level N2 and a neutron flux level Nn is determined. -Nn (neutron flux level deviation) is calculated, and the deviation is substituted into the membership function shown in Figure 6. Positive and large (P B) grade, positive and small (ps) grade, zero (20 ) grade, negative less (NS) grade, and negative greater (NB) grade. Then, the fuzzy control rules shown in Table 1 below are executed to determine membership functions corresponding to the control rod position command Z and the control rod insertion/extraction speed V, respectively.

In addition, the fuzzy set of control rod position command Z1 and control rod insertion/extraction speed■ is positive and large (PB), and positive and small (PS).
The fuzzy set, zero (20) fuzzy set, negative small (NS) fuzzy set, and negative large (NB) fuzzy set are defined by the membership functions shown in Figures 7 and 8, respectively. do.

Next, in step S45, the membership functions of the control rod position command Z obtained by executing the fuzzy rule are combined, and the center of gravity thereof is set as the control rod position command Z.

For example, if the position deviation is PB in a grade of 0.7 and the neutron flux level deviation is PB in a grade of 0.4, the control rod position command Z is set to a positive and large value (P B), and its membership The function has a function form shown in FIG. 9 in which the minimum value of 0.4 between the grade of position deviation PB and the grade of neutron flux level deviation PB is the maximum. Also, the positional deviation is 0.
PS with grade 3, neutron flux level deviation is 0.6
In the case of PS with a grade of The function form shown in FIG. 10 is assumed to be the maximum. Then, as shown in FIG. 11, the membership function in FIG. 9 and the membership function in FIG. 10 are combined, and the center of gravity Z thereof is used as a control rod position command. Furthermore, in the same way as combining the membership functions of the control rod position command Z, and setting the center of gravity as the control rod position command Z, each membership function of the control rod insertion/extraction speed V is obtained by executing fuzzy rules. and control rod insertion/extraction command V
shall be.

Next, the processing in the constraint fuzzy control unit 23c is
This will be explained with reference to the flow chart shown in FIG.

First, in step 5121, the control rod insertion/extraction speed V and the neutral flux level change rate DN are read from the predictive fuzzy control unit 23b. Let it be a fuzzy set defined by a function.

Next, in step 5122, the neutron flux level change rate DN is determined by the membership function shown in FIG.
Just right (MED I UM) or too big (B
IG). DNL shown in FIG. 14 is a constraint on the operation of the neutron flux level change rate DN, and is predetermined.

Next, in step 8123, the fuzzy control rules shown in Table 2 below are executed, and the control rod drive speed command V,
Define the membership function corresponding to .

Here, V in Table 2 is 0 as shown in Figure 15.
Let it be a fuzzy set defined by a membership function centered at 10.

Next, the member functions corresponding to the control rod drive speed command V obtained by executing each fuzzy rule are synthesized, and the center of gravity thereof is set as the control rod drive speed command V. In other words, the combined form of each membership function corresponding to control rod drive speed command] is as shown in Fig. 16, and the maximum of the membership functions of ■ is MEDIUM of the neutron flux level change rate DN. It is a composite of the function form limited by grade LH and the function form limited by grade LB, which is the BIG of the neutron east level change rate DN, and the maximum of the membership function of ■, and its center of gravity is the control rod drive speed command. V, becomes.

In this way, in order to predict the control rod position at the critical time based on the change in the neutron flux level after control rod operation, and to set an appropriate control method based on the behavior of the neutron flux level during control rod operation, Reactor power can be automatically controlled stably even up to criticality, where the neutron flux level response to control rod operations is highly nonlinear.

Further, the burden on the operator is reduced, and there is no problem that the output control characteristics are influenced by the experience and skill of the operator, and operational controllability can be improved.

〔Effect of the invention〕

As explained above, the present invention includes a monitoring section, a predictive fuzzy control section, and a constraint fuzzy control section, so that it is possible to stably and automatically control the reactor output from the reactor shutdown state to criticality. This makes it possible to improve plant operation controllability.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a reactor power control device according to an embodiment of the present invention, Fig. 2 is a block diagram showing a reactor equipment equipped with this reactor power control device, and Fig. 3 is a block diagram showing a reactor power control device according to an embodiment of the present invention. Flowchart showing the processing procedure, Fig. 4 is a flowchart showing the processing procedure in the predictive fuzzy control section, Fig. 5 is a graph showing the membership function that is the criterion for control rod position deviation, and Fig. 6 is a graph showing the neutron flux level deviation. A graph showing a membership function used as a determination criterion, and FIG. 7 is a graph showing a membership function for determining a control rod position command.
Fig. 8 is a graph showing a membership function for determining control rod insertion/extraction speed, Fig. 9 is a graph showing an example of a membership function when the control rod position command is a positive and large value, and Fig. 10 is a graph showing the control rod position. A graph showing an example of a membership function when the command is a positive and small value, FIG. 11 is a graph showing an example of combining membership functions of control rod position commands, FIG. 12 is a flowchart showing the processing procedure in the constrained fuzzy control unit, 1st
FIG. 3 is a graph showing a membership function of control rod insertion/extraction speed, FIG. 14 is a graph showing a membership function for determining the neutron flux level, and FIG. 15 is a graph showing an example of a membership function of control speed. Figure 16 is a graph showing an example of composition of membership functions of control rod drive speed commands;
The figure is a system diagram showing a conventional nuclear reactor plant. 1... Nuclear reactor, 12... Neutron detector, 14...
Control rod drive mechanism, 15... Control rod, 20... Control rod position detector, 21... Differentiator, 23... Reactor power control device, 23a... Monitoring unit, 23b... Predictive fuzzy control unit, 23C... Constraint fuzzy control unit.

Claims (1)

[Claims] In a reactor power control device that controls the output of a nuclear reactor by giving a control rod drive speed command signal to a control rod drive mechanism, input of a neutron flux level, a rate of change in neutron flux level, and a control rod position signal is provided. A monitoring unit that determines the stability of the reactor, and a fuzzy A predictive fuzzy control unit that sets the position and speed of control rod withdrawal or insertion based on inference; and a predictive fuzzy control unit that sets the control rod withdrawal or insertion position and speed by inference; and a predictive fuzzy control unit that sets the control rods set by the predictive fuzzy control unit by inputting various process variables around the reactor, such as neutron flux level change rate. A nuclear reactor power control device comprising: a constraint fuzzy control unit that corrects the speed of withdrawal or insertion of the fuel by fuzzy reasoning;