JPH0454497A - Operation controller for pressurized water reactor - Google Patents

Abstract

PURPOSE:To decrease an operator's burden by automatically controlling the operation of a reactor in such a manner that an axial neutron flux deviation enters the upper and lower limit range thereof at the time of a load follow-up operation. CONSTITUTION:The make-up water volume of the reactor necessary for the burnup is set by a load change start signal at the time of the load follow-up operation. The automatic make-up including the automatic selection of 'diluting' or 'concentrating' of boron is then started. A coolant average temp. TAVG is controlled by monitoring the relation between the coolant average temp. TAVG and a coolant program reference temp. Tref and automatically adjusting the make-up water volume during the load change. Further, the insertion and withdrawal of control rods are automatically executed by the relation between the temp. TAVG and the reference temp. Tref, the tendency thereof and the actual axial neutron flux deviation to maintain the axial neutron flux deviation within the target range. The control of the make-up water volume is executed by comparing the range thereof with the control range of a regulating valve for the make-up water volume and is automatically switched to a batch control at a certain point of time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an operation control device for load following operation of a pressurized water nuclear reactor.

[Prior Art] Core power control of a pressurized watercolor nuclear reactor plant is performed by controlling the control rod position and the boron concentration in the coolant in the reactor coolant system. Control rod control is used for large and fast reactivity changes.

Therefore, when operating at a constant output such as during normal operation, the control rods are not operated, and the control rods are used at a position near the fully withdrawn state for the purpose of flattening the core power distribution. Ru. Boron concentration control in the coolant is used for gradual reactivity control, such as reactivity compensation by combustion during constant output car operation. This is compensated for by diluting the boron concentration.

On the other hand, in response to changes in power demand, an operation mode that immediately responds to the load at each point in time, such as load following operation, takes 24 hours a day as one cycle and, for example, changes the output from 100% to 50% in 3 cycles. time, 50% retention for 6 hours, 50
% → 100% for 3 hours and 100% held for 12 hours, the load change is large,
Therefore, if the reactivity change is large, the power distribution of the core will change significantly if control rods alone are used, so both the control rod position and boron concentration should be adjusted to flatten the power distribution. Therefore, it is necessary to control the axial neutron flux deviation within the core so as to bring it as close to the target value as possible while maintaining it at least within its upper and lower limits.

Increasing the boron concentration is referred to as enrichment, and this is done by adding boron to the coolant system, and also.

Decreasing the boron concentration is called dilution, and this is done by adding pure water to the coolant system, and such addition of boron and pure water is generally referred to as make-up water control.

The guideline for this make-up water control is the primary system output, or coolant average temperature (TAv,), the secondary system output, or program reference temperature (T,,), and the control rod position or axial neutron flux deviation (ΔI ), and concentration and dilution operations are performed.

However, in order to perform such control, operators must monitor and predict various plant parameters such as the average coolant temperature TAVQ and the program reference temperature Tr*f.
Various manual operations, such as adjusting the amount of make-up water, must be performed quickly and accurately, otherwise the axial neutron flux deviation will deviate significantly from the target value.

Taking the case of a load drop as an example, 1. Due to the load drop, the core output must also be lowered.

2. To reduce the core power, insert control rods and add boron.

3. If the degree of insertion of the control rod becomes too large, the neutron flux deviation increases to the negative side and deviates from the control range, so boron addition is controlled by the amount of make-up water in order to suppress the degree of insertion.

4. At this time, if the boron addition is too large, the generator output will be greater than the reactor output, the average coolant temperature TAVG will drop, and unnecessary operations such as control rod withdrawal or dilution operations will be required. For this reason, the generator output reactor output, that is, TAVeΣ
The amount of makeup water is manually controlled to maintain the Trot relationship.

5. In other words, this make-up water control is determined by the operator based on the Tava Tr* and trends.

6. When the output is maintained, the output loss reactivity disappears, so
Control over changes in xenon reactivity is required.

7. At this time, xenon has risen to the negative side, and it is necessary to switch the mode to dilution operation.

8. Also, when holding the output, there is no need to operate the control rods in principle, and only the constant TAV = Tref control is performed.

This control is also performed by controlling makeup water in the same manner as described above.

9. The same applies when the load increases, but the concentration and dilution modes are opposite to those when the load decreases.

10. At any time, if the amount of make-up water decreases due to the influence of xenon, it will exceed the control range of the valve, so control will be switched from continuous flow rate control to batch control.

Operators perform the operations and judgments described above based on various parameters, and are constantly performing careful operations.

[Problem to be solved by the invention] Therefore, operators who had to perform various operations manually are required not only to have long experience but also to have a high degree of skill, skill, and judgment. like 1 day 2
Since load following operation is performed every day with one cycle of 4 hours, the physical and mental burden on the operators has increased significantly, and we are heading into a situation where we can no longer leave things as they are.

Therefore, an object of the present invention is to provide a device that automatically controls the operation of a nuclear reactor so that the axial neutron flux deviation falls within its upper and lower limits during load following operation.

[Means for Solving the Problems] In order to achieve this object, according to the present invention, an operation control device during load following operation of a pressurized water reactor having a primary cooling system and a secondary cooling system receives a load change start signal. According to
A make-up water amount setting device that sets the make-up water amount of the primary cooling system necessary for the core state at that time and outputs a signal to automatically start replenishment; and a coolant average that represents the output of the primary cooling system during load changes. a monitoring/adjusting device that monitors the relationship between the temperature and a coolant program reference temperature representing the output of the secondary cooling system, automatically adjusts the amount of make-up water, and controls the average coolant temperature; A maintenance device that automatically inserts and withdraws control rods based on the relationship and tendency between temperature and the program reference temperature and the actual axial neutron flux deviation to maintain the axial neutron flux deviation within a target range; A switching device automatically switches make-up water flow control from initial continuous control to batch control based on the rise of a mode selection device that automatically selects a mode and communicates the selected mode to the make-up water amount setting device; and a replenishment device that automatically adjusts the make-up water amount by controlling the make-up water amount when the output is maintained in the same way as when the load changes. It is equipped with a water amount adjustment device and a reversal detection device that detects the reversal based on the xenon calculation result and automatically switches the mode of makeup water by reversing the xenon when the output is maintained.

[Operation] For example, in load drop mode, when load drop starts, the reactor make-up water system selects enrichment mode, and replenishment is automatically started at a flow rate that is the program flow rate multiplied by the burnup coefficient. .

At this time, an increase/decrease signal for the make-up water amount is issued at regular intervals based on the temperature difference and trend between the average coolant temperature Tavo and the program reference temperature Traf, and the flow rate of the make-up water amount is adjusted to match the set value. In addition, the control rods are TAVII, T
One step at a time is inserted under the conditions of raf temperature difference and axial neutron flux deviation. If the axial neutron flux deviation deviates significantly, the axial neutron flux deviation will be brought back by continuous insertion and withdrawal.

When the make-up water flow rate decreases due to the influence of xenon and is below the flow control lower limit value of the control valve and a signal to reduce the flow rate is received, continuous control is automatically switched to batch control. Batch control is
Replenish a certain amount of water when a flow increase signal is issued 5
In this state, the load is lowered from 100% to 50%.

Since it is necessary to switch the make-up water mode based on the load drop signal, the mode is switched using the exclusion signal of the automatic load adjustment device.The initial flow rate setting is also set at the same time to control the amount of make-up water.

Switching from continuous to batch control when holding the output is the same as described above, but when switching to make-up water mode, the mode switching is performed based on the xenon calculation results and taking into account the time when xenon is inverted.

The above description has been made regarding the time when the load decreases and the time when the output is maintained, but the operation is almost the same when the load increases, except that the initial mode starts from the dilution mode, and the following characteristic control is performed.

(1) The relationship between TAVO and Tear when the load drops is Tav
2) The relationship between TAVO and Trat when the load increases is TAV
(Control to i≦T1.).

(3) When holding the output, control TAVll=Trsf.

[Embodiment] First, an outline of the procedure for performing load following operation according to the present invention will be described below.

(1) The core condition at that time is determined by the load change start signal. Set the amount of reactor make-up water required for (burnup), "dilution", "
Replenishment will begin automatically, including the automatic selection of "Concentration".

(2) During load changes, the relationship between the average coolant temperature TAV6 and the coolant program reference temperature Tref is monitored, the amount of make-up water is automatically adjusted, and the average coolant temperature Tava is controlled.

(3) Furthermore, the control rods are automatically inserted and withdrawn based on the relationship and tendency of the coolant average temperature TAVO and the program reference temperature T a, r, and the actual axial neutron flux deviation to achieve the target axial neutron flux deviation. Stay within range.

(a) Makeup water amount control is initially continuous control, but it is necessary to switch to batch control when xenon Xe rises. Regarding this, the system will compare the control range of the make-up water amount adjustment valve and automatically switch to batch control at a certain point.

(5) Immediately after the end of the load change, the "dilution J" and "concentration" modes are reversed, so the mode is automatically selected based on the load drop completion signal, the required amount of replenishment water is set, and replenishment is started.

(6) Regarding the control of the amount of make-up water while maintaining the output, the amount of make-up water is automatically adjusted in the same way as when the load changes.

(7> When maintaining the output, the mode of makeup water is switched by inversion of xenon Xe. The inversion is detected from the xenon χe calculation result and the mode is automatically switched.

Next, regarding the control device of the present invention for performing load following operation based on the above-mentioned procedure, the reactor make-up water flow control logic is shown in FIGS. 1 and 2, and the control rod control logic is shown in FIG. 3. This will be explained in detail with reference to .

First, FIGS. 1 and 2 show the make-up water control logic at the time of load change and at the time of load maintenance, respectively, and the control logic includes logic circuits (1) to (2). In the logic circuit ①, the boron concentration in the reactor coolant system RCS usually ranges from 1500 ppm to 1 from the early core to the final core.
Although it is operated at 0 ppm, the flow rate is different during concentration (boron addition) and dilution (pure water addition) even if the rate of change in boron concentration is the same, so the program for concentration and dilution is different. A flow rate is provided. in this way,
Since the boron concentration changes depending on the operating period, the burnup (the integrated value of the energy generated by nuclear fission relative to the loaded fuel) is used as a parameter to compensate for the effect of this on the enrichment rate and dilution rate. ing. Specifically, the operating conditions are stored, the burnup is calculated from the data, and the program flow rate is determined. In the logic circuit (makeup water amount setting device), when the concentration signal 2a or dilution signal 2b from the logic circuit (mode selection device) enters the switching element 1a or 1b, the program flow rate set as described above is output. be done. That is, the initial flow rate of make-up water is given by changing the coefficient depending on the core state at the time of signal input.

In the logic circuit ■, the output increases during load following operation,
When descending, "concentration" and "dilution" modes are patterned, and AND circuits 2a-1 and 2b-1 are used to control the generator load at a set rate of change for a set target. When a signal from the automatic load adjustment device (^LP) that does not operate is input, that is, when a signal indicating the start of an output change is input, the above-mentioned signals 2a and 2b (load change start signal) are activated depending on whether the load is increasing or decreasing. is output.

In logic circuit ■ (monitoring/adjusting device), TAv
c is the average temperature of the primary coolant, and in the case of a pressurized water reactor, this TAVO is programmed for the load,
It represents the primary system output. Further, Trsf is a reference average temperature programmed from the pressure after the first stage of the turbine, and represents the secondary system load. In plant operation, it is necessary to control TAVO, which is the primary system output, and Trer, which is the secondary system output, within a certain range.
This is a secondary system-based operation that also changes the secondary system output. Changes in the primary system output are caused by control rod position control and RC
Since this is done by controlling the S boron concentration, the TAv
The deviation between c and Tr*-r is monitored and used to control makeup water and control rods. When the load decreases, TAv
When a≧T1.2 and the load increases, control is performed to maintain the state of TAVO≦Traf, and the operational margin of the control rod is also taken into consideration.

Furthermore, since TAVC, Tr, and t are oscillating at high frequencies, the logic circuit (2) includes a first-order lag element LAG in order to input a first-order lag into the adder 3a as a flat signal. The output of the adder 3a is input to the logic circuit (2) and also to the port 1 of the logic circuit (2) in FIG.

Logic circuit■ (monitoring/adjustment device) is a logic circuit■
Monitors 4a, 4b, 4C5 connected to adder 3a of
4d and the logic circuit ■ receive the concentration signal from the ND circuit 2a-1 ND circuits 4e and 4f and the logic circuit ■
The logic circuit ■ includes ND circuits 4g and 4h that receive the dilution signal from the ND circuit 2b-1, and the Lvc and T
In addition to the deviation of ret, monitor whether this deviation tends to increase or decrease and generate an increase/decrease signal for the amount of make-up water. For example, if concentration is started due to a load drop and TAVG exceeds a certain value with respect to Trsl, 1 by monitors 4a and 4b
It is difficult to judge that the output of the secondary system is larger than the output of the secondary system.TAv
G>T,...), a signal is generated to increase the concentration amount in order to quickly lower the primary system output, and is applied to the make-up water control of the logic circuit (2) via the ND circuits 4e and 4f.

As can be seen from the logic circuit ■, at this time, the dead time element 4i (dead time τ=30 sec) - the positive/negative inversion element 4j
, the adder 4k, the monitor 41 (the output turns on when the output to the adder 4 is 0 or more), the monitor 4 (the output turns on when the output to the adder 4 is less than or equal to O), etc. We are monitoring the increase/decrease trend - TAvc>
It is necessary to be in the state of Tr++t and to have an increasing tendency. On the other hand, if there is a decreasing trend in the above condition, TA V C=T
It is determined that the temperature is approaching r a f, and no make-up water increase signal is output even if there is a temperature difference. TAv5
(The same concept will be used to determine the Tret status, and a signal to reduce the supply water will be given.

In the logic circuit ■, the ^ND circuit 4e of the logic circuit ■
, 4f, 4FK, 4h signals and actual replenishment mode (
Concentration increase or decrease and dilution increase or decrease signals are created from the combination with the concentration mode or dilution mode) and input to the logic circuit (2). That is, the logic circuit (2) has two pairs of AND@ circuits that receive signals from each one AND circuit of the logic circuit (2), for a total of eight ^ND circuits 5a to 5h, and each pair of AND circuits has a concentration circuit. A mode signal and a dilution mode signal are input. Of these AND circuits 58 to 5h, ^ND times N5b, 5d
, 5f, 5g are connected to the OR circuit 51, and the ND circuit 5
a, 5c, 5e, and 5h are connected to an OR circuit 5j. Furthermore, the outputs of these OR circuits 51.5j are sent to another N
Connected to D times #35k and 51, respectively, on-delay timers 5-15n (output turns on after a predetermined time from input), NOT circuits 5o and 5p, and on-delay timer 5q.
, 5r, ^ND circuits 5s, 5t to output a signal representing "increase" and a signal representing "decrease" to ND circuits 5u, 5v,
Send to 5-15x. A dilution mode signal and an increase signal are connected to the ND circuit 5u, and when both are input, it indicates a dilution increase (rare increase), and a dilution mode signal and a decrease signal are connected to the AND circuit 5v, and both are input. When dilution decreases (
A concentration mode signal and an increase signal are connected to the AND circuit 5w, and when both are input, it represents a concentration increase (concentration increase).A concentration mode signal and a decrease signal are connected to the AND circuit 5x. and represents a decrease in concentration (collapse) when both input.

The logic circuit (2) (monitoring/adjusting device) receives the initial flow rate set by the logic circuit (2) and the increase/decrease signal from the logic circuit (2) and calculates the increase/decrease in the flow rate. Concentration and dilution have different effects on the core even if the flow rate is the same, so they are divided into two systems. Furthermore, although the flow rate is changed using the increase/decrease signal, the range of change is also separated so that it can be set in consideration of the actual machine.

That is, the flow rate change range is given by constant setters 6a to 6d for each increase or decrease in concentration and dilution, and adders 6e, 6f61.
6j and integrators 6g and 6h, the flow rate setting is calculated based on the initial flow rate set by the logic circuit (2). In addition, the "^LR switching reset" signal is input to each system, and the ^LR is "
By changing from "use" to "exclude", integrator 6g, 6
The value of h is reset to 0.

Next, in the logic circuit (2), the flow rate calculated in the logic circuit (2) is transferred to a flow rate controller, that is, a boric acid flow rate controller FC-22.
0. Since the boric acid flow control valve and the pure water flow control valve of the flow rate controller such as Ni, which is applied to the pure water flow rate controller FC-223, have a limit value of the flow rate control range, the calculated flow rate of the logic circuit Once the critical flow rate is reached, ensure that the flow does not fall below that value.
The logic circuit ■ has a limiter or limiter 7a, 7b.
is provided. The limiter 7a outputs an input representing the flow rate between 0806 and 2.5, and when the input is smaller than 0.06, it outputs this 0.06, and when the input is larger than 2.5, it outputs this 2.5. Output. The limiter 7b outputs an input representing a flow rate between 1.5 and 4.0, and an input representing a flow rate of 1.5 to 4.0.
．． If it is smaller than 5, it outputs this 1.5 and the input is 4.
If it is greater than 0, output this 4.0. Limiter 7
The maximum values expected to be necessary for control are set as the upper limit values of a and 7b. In addition, if the set flow rate is below the lower limit value even after reaching the lower limit flow rate and a certain period of time has passed, it is determined that the flow rate is greater than the required flow rate, and in order to switch from continuous control to batch control, these limiters 7a, 7b has a monitor 70.7d (switching device) and a monitor 70.7d that turns on the output when the input is 0.06.1.5 or less.
On-delay timers 7e and 7f (switching devices) whose outputs are turned on 360 seconds from the input of d are connected. Memories 7i and 7j are connected to the on-delay timers 7e and 7f via AND circuits 7g and 7h, respectively, which receive output signals from the ^ND times H5× and 5v of the logic circuit (■). 71.7j holds the output when there is an input from the ND circuits 7g and 7h, and resets the output with the signal from the LR switching reset.

Although the above is the case when the load changes, the concept is basically the same when the load is maintained or the output is maintained, and FIG. 2 shows the make-up water control block at that time.

In FIG. 2, the logic circuit (2) (device for adjusting the amount of make-up water during load maintenance) is the same as the logic circuit (2) described above. However, since this is control during load holding, the selection of concentration and dilution uses the ^LR exclusion signal. The change in reactivity when the load is maintained is basically due to the influence of Xe, and there is no large change in reactivity as when the load is changed. Therefore, since the program flow rate shown in FIG. 1 cannot be used as the program flow rate, a new flow rate for load holding is set. Also, Xe
Since the effect does not change depending on the core life, the burnup coefficient is set to 1.0. In the logic circuit (2), reference numeral 8a is an OR circuit whose output is input to the NOT circuit 9a of the logic circuit (2). Further, the outputs of the switching elements 1a and 1b of the logic circuit (■) are respectively input to adders 61.6j of the logic circuit (■), and a batch switching signal is transmitted in the logic circuit (■) according to the outputs thereof. It looks like this.

In the logic circuit ■, after transmitting the batch switching signal, the same signal and the dilution increase (dilution increase) and concentration increase (podium) signals from the ^ND circuits 5u and 5w of the logic circuit ■ are connected to the ^ND circuit 9.
The timing of batch replenishment is determined by combining a, 9b, 9c, and 9d.

The logic [phase] (reversal detection device) determines the reversal of Xe when the load is held and determines the timing of switching the replenishment mode. The behavior of Xe matches the calculations very well, and since the calculations are constantly performed by a computer in the plant, it is possible to determine the timing of switching the replenishment mode by monitoring the computer output. That is, the logic circuit [phase] includes AND circuits 10m and 10b which receive the outputs of the ^ND circuits 9a and 9b of logic circuit (2) at one input port, and an AND circuit 10m of these to monitor the increase/decrease trend of Xe. Dead time element 10e (dead time τ=600se
c) - positive/negative inversion element 10d, adder 10e, monitor 1
of (the output is turned on when the output of the adder 10e is 0 or less) and a monitor 10g (the output is turned on when the output of the adder 10e is 0 or more).

Logic circuit (2) represents the TAv: control block when the load is held. When decreasing and increasing the output, TAvc≧Tref+ TAVO≦T from the viewpoint of control rod operation margin.
The control was performed to maintain the state of rsf, but when the load is maintained, the control is such that TAVC=Tr@f. In other words, it is not necessary to operate the control rods when the load is maintained, and TAVO is controlled so that the control rods are not operated.

In addition, in the logic circuit ■, the symbols 11a and llb are T.
This is a monitor that is turned on and off in response to six deviations of AVC and T, . Reference numerals lie to llb are ND circuits, and numerals 11i and llj are OR circuits.

Next, the logic of control rod control will be explained with reference to FIG.

In order to perform load following operation, reactivity control and output distribution control are required for output fluctuations, and reactivity control is carried out using control rods and make-up water control in combination, as described above. . Output distribution control is a constant axial deviation control (C^
OC) driving method is adopted. ΔI sub-control is Mm I
Since the position of I has a large effect, it is necessary to constantly monitor the actual AI and ΔI target value, and control the amount of movement of the control rod by makeup water control. 0 Control rod control during normal operation is as follows:
It is controlled by the TAvc and Trot deviation and output mismatch circuits (mismatch between nuclear instrumentation system output and turbine output).

When changing the load such as during load following operation, if only the normal control system is used, the amount of movement of the control rods will increase, and the AI will deviate significantly from the target value. Therefore, it is preferable to also monitor the ΔI deviation and provide feedback.

That is, in the logic circuit @ (maintenance device) of FIG.
Control over TAVO's Trll+ was performed in the previous make-up water control, and here the timing to operate the control rods was determined based on the ΔI deviation signal. Control rod movement and A
The relationship between I is that as the control rods are inserted, the output at the top of the core decreases, and AI becomes negative (-) in proportion to the amount of control rod movement.
) side. For this reason, the control rods must be operated one step at a time. In the logic circuit @, symbols 12 a to 12 d are monitors, symbols 12 e to 12 h are ^ND circuits, and symbol 12 i
~121 is an on-delay timer, code 12s ~1
2n is a NOT circuit.

Considering the load drop, (1) TAv is controlled by the make-up water system so that TAVC≧T1.
．． , maintain.

(2) This allows for extra control rod insertion (Due to ΔI sub-control, a certain amount of control rod insertion is required when the load drops).

In other words, control is performed in anticipation of a drop in TAVc due to control rod insertion).

(3) The behavior of AI during load reduction is that when Tavc falls due to control rod insertion or boron injection, and TAVG falls, Δ■ increases due to the feedback of the moderator temperature coefficient (core characteristics). Become.

(4) By capturing this phenomenon, the control rod insertion at load drop is T
Avo>Trot and AI are set to the plus (-) side.

(At this time, due to the insertion of the control rod, the AI becomes negative (-
) side and is maintained within the target range.

(6) The opposite is true when the load increases.

In the logic circuit (■) in Fig. 3, the control rods are controlled by the control of the logic circuit @, but for example, the TA
When the ΔI deviation exceeds a certain value, it is considered that the deviation of the AI is large, and the control rods are operated to bring the AI into the target range, taking into consideration cases where the VG is poorly controlled. That is, the logic circuit (2) includes monitors 13a, 13b and an OR circuit 13e,
When AI deviates to the plus side, a control rod is inserted to shift AI to the minus side, and when Δ■ deviates to the plus side, the control rod is pulled out and AI shifts to the plus side.

[Effects of the Invention] According to the operation control device of the present invention having the above-described configuration, conventionally, all operations were performed by monitoring, judgment, and manual operation by the operator, and the operation period was long, so the burden on the operator was reduced. By automating a series of tasks that used to be extremely burdensome, the burden on the operator can be reduced, and operation timing can be automatically determined and controlled, making it possible to prevent operations.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram of reactor make-up water control logic when the load changes by the operation control device of the present invention, and FIG. 2 is a conceptual diagram of the reactor make-up water control logic when output is maintained by the operation control device of the present invention. 3 are conceptual diagrams of control rod control logic by the operation control device of the present invention. ■... Logic circuit (makeup water amount setting device) ■... Logic circuit (mode selection device) 2a... Concentration signal (load change start signal) 2b... Dilution signal (load change rM start multiplication signal ■, ■, ■...Logic times n<monitoring/adjusting device) 7a, 7b...monitor (switching device) 7e, 7''.
...On-day timer (switching device) ■Logic circuit (makeup water amount adjustment device) ■...Logic circuit (reversal detection device) ■...Logic circuit (maintenance device) Applicant: Ryoju Industries Co., Ltd.

Claims (1)

[Scope of Claims] An operation control device during load following operation of a pressurized water nuclear reactor having a primary cooling system and a secondary cooling system, which controls the primary cooling system according to the core state at that time according to a load change start signal. a make-up water amount setting device that sets a make-up water amount and outputs a signal to automatically start replenishment; and during a load change, a coolant average temperature that represents the output of the primary cooling system and an output of the secondary cooling system. A monitoring/adjusting device that monitors the relationship with the coolant program reference temperature, automatically adjusts the amount of make-up water, and controls the coolant average temperature; and the relationship and trend between the coolant average temperature and the program standard temperature. , as well as a maintenance device that automatically inserts and withdraws control rods based on the actual axial neutron flux deviation to maintain the axial neutron flux deviation within the target range, and a maintenance device that automatically controls the amount of make-up water based on the rise of xenon. A switching device automatically switches from continuous control to batch control, and since the boron dilution and concentration modes are reversed immediately after the load change ends, the mode is automatically selected by the load drop completion signal, and the selected mode is a mode selection device that communicates the make-up water amount setting device with the make-up water amount setting device; a make-up water amount adjusting device that automatically adjusts the make-up water amount by controlling the make-up water amount when the output is held in the same way as when the load changes; An operation control device for a pressurized water reactor, comprising: a reversal detection device that detects the reversal based on xenon calculation results and automatically switches the make-up water mode due to the reversal.