JP7267093B2 - NUCLEAR POWER PLANT CONTROL DEVICE, NUCLEAR POWER PLANT AND NUCLEAR POWER PLANT CONTROL METHOD - Google Patents

Description

The present invention relates to a control device for a nuclear power plant, a nuclear power plant, and a control method for a nuclear power plant.

Conventionally, technologies related to nuclear power plants are known. For example, Patent Literature 1 discloses a nuclear power plant in which steam generated in a reactor pressure vessel flows into a turbine through a main steam pipe to rotate a generator connected to the turbine.

JP 2009-235949 A

2. Description of the Related Art In recent years, in nuclear power plants, there is an increasing need to implement constant rated thermal power operation in which the thermal power of a nuclear reactor is set to a specified rated thermal power. Constant rated thermal output operation keeps the thermal output of the nuclear reactor constant, so it is possible to increase the amount of power generated compared to constant rated electrical output operation in winter when the seawater temperature is low and power generation efficiency is high. In such a constant rated thermal power operation, it is necessary to prevent the thermal power from exceeding the rated thermal power. Therefore, conventionally, an operator manually increases the heat output gradually over a long period of time so as to suppress the overshoot of the heat output caused by the control delay, leading to an increase in the work load.

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and is intended to automatically bring a nuclear power plant into operation at a constant rated thermal output while satisfactorily preventing the thermal output of a nuclear reactor from exceeding the rated thermal output. intended to migrate.

In order to solve the above-described problems and achieve the object, the control apparatus for a nuclear power plant according to the present invention provides a control apparatus for a nuclear power plant in which the thermal output of a nuclear reactor is The controlled object is controlled to increase the thermal output at a first rate until a predetermined upper limit output lower than the rated thermal output is reached, and when the thermal output reaches the predetermined upper limit output, the control target is increased from the first rate The controlled object is controlled so as to gradually increase the thermal output.

In order to solve the above-described problems and achieve the object, the nuclear power plant of the present invention includes a primary cooling system including a nuclear reactor, and a turbine rotated by heat obtained by heat exchange with the primary cooling system. A secondary cooling system and a control device for the nuclear power plant that controls a controlled object to adjust the thermal output of the nuclear reactor.

In order to solve the above-described problems and achieve the object, the method of controlling a nuclear power plant according to the present invention provides a method of controlling a nuclear power plant when the thermal output of a nuclear reactor is shifted to a constant rated thermal output operation in which the thermal output is the rated thermal output. The controlled object is controlled to increase the thermal output at a first rate until a predetermined upper limit output lower than the rated thermal output is reached, and when the thermal output reaches the predetermined upper limit output, the control target is increased from the first rate The controlled object is controlled so as to gradually increase the thermal output.

A control device for a nuclear power plant, a nuclear power plant, and a control method for a nuclear power plant according to the present invention automatically control the nuclear power plant while satisfactorily suppressing the thermal output of the nuclear reactor from exceeding the rated thermal output. There is an effect that it is possible to shift to rated thermal output constant operation immediately.

FIG. 1 is a schematic configuration diagram of a nuclear power plant according to an embodiment. FIG. 2 is an explanatory diagram showing temporal changes in the thermal output of a nuclear reactor when transitioning to constant rated thermal output operation. FIG. 3 is a flowchart illustrating an example of a method for controlling a nuclear power plant according to the embodiment;

EMBODIMENT OF THE INVENTION Below, embodiment of the control apparatus of a nuclear power plant, a nuclear power plant, and the control method of a nuclear power plant concerning this invention is described in detail based on drawing. In addition, this invention is not limited by this embodiment.

FIG. 1 is a schematic configuration diagram of a nuclear power plant according to an embodiment. The nuclear power plant 1 includes a primary cooling system (reactor cooling system) 100 including the reactor 2 and a secondary cooling system (turbine system) 200 that exchanges heat with the primary cooling system 100 . A primary coolant flows through the primary cooling system 100 , and a secondary coolant flows through the secondary cooling system 200 . In this embodiment, the nuclear reactor 2 is a pressurized water reactor (PWR). The reactor 2 may be a boiling water reactor (BWR).

(Primary cooling system)
The primary cooling system 100 has a steam generator 4 connected to the reactor 2 via a cold leg 3a and a hot leg 3b. A pressurizer 5 is provided in the hot leg 3b, and a primary coolant pump 6 is provided in the cold leg 3a. The reactor 2 , cold leg 3 a , hot leg 3 b , steam generator 4 , pressurizer 5 and primary coolant pump 6 are housed in a reactor containment vessel 7 .

The reactor 2 is a pressurized water reactor as described above, and its interior is filled with a primary coolant. The primary coolant is light water with dissolved boron used as a neutron moderator. In the reactor 2, a large number of fuel assemblies 8 are housed inside a reactor vessel 10, and a large number of control rods 9 for controlling nuclear fission of the fuel assemblies 8 are inserted into and removed from the respective fuel assemblies 8. provided as possible.

A series of operations in the primary cooling system 100 of the nuclear power plant 1 will be described. In the nuclear reactor 2, when the fuel assemblies 8 are fissioned while the nuclear fission reaction is controlled by the control rods 9, thermal energy is generated by nuclear fission. When the primary coolant in the reactor 2 is heated by this thermal energy, the heated primary coolant is sent by the primary coolant pump 6 to the steam generator 4 via the hot leg 3b. The high-temperature primary coolant passing through the hot leg 3b is pressurized by the pressurizer 5 to suppress boiling, and flows into the steam generator 4 in a high-temperature, high-pressure state. The high-temperature, high-pressure primary coolant that has flowed into the steam generator 4 is cooled by performing heat exchange with the secondary coolant, and the cooled primary coolant is pumped by the primary coolant pump 6 through the cold leg 3a to the reactor. sent to 2. Then, the cooled primary coolant flows into the reactor 2 to cool the reactor 2 . Thus, the primary coolant circulates between the reactor 2 and the steam generator 4 .

(Secondary cooling system)
The secondary cooling system 200 includes a turbine 12 connected to the steam generator 4 via a steam pipe 11, a condenser 13 connected to the turbine 12, and a feed water supply connecting the condenser 13 and the steam generator 4. It has a water supply pump 15 interposed in the pipe 14 and a steam control valve 20 provided in the steam pipe 11 . A generator 16 is connected to the turbine 12 . The steam control valve 20 is a valve that adjusts the flow rate of steam sent from the steam generator 4 to the turbine 12, and its opening is controlled by a control device 50, which will be described later.

A series of operations in the secondary cooling system 200 of the nuclear power plant 1 will be described. When steam flows into the turbine 12 from the steam generator 4 via the steam pipe 11, the turbine 12 rotates. As the turbine 12 rotates, a generator 16 connected to the turbine 12 produces electricity. After that, the steam that has flowed out of the turbine 12 flows into the condenser 13 . The condenser 13 has a cooling pipe 17 disposed therein. One end of the cooling pipe 17 is connected to a water intake pipe 18 for supplying cooling water (eg, seawater), and the other end of the cooling pipe 17 is connected to a drain pipe 19 for draining cooling water. The condenser 13 cools the steam that has flowed in from the turbine 12 through the cooling pipe 17 to return the steam to liquid. The liquid secondary coolant is sent to the steam generator 4 via the water supply pipe 14 by the water supply pump 15 . The secondary coolant sent to the steam generator 4 becomes steam again by exchanging heat with the primary coolant in the steam generator 4 .

(control system)
The nuclear power plant 1 also includes a control system 300 that controls the primary cooling system 100 and the secondary cooling system 200 . The control system 300 is provided with a controller 50 to which various plant data and parameters are input and which controls the primary cooling system 100 and the secondary cooling system 200 based on the plant data. The control device 50 is a control device equipped with an arithmetic device such as a CPU, various programs executed by the arithmetic device, and a storage device such as an HDD for storing data necessary for executing the various programs.

The plant data input to the controller 50 include, for example, the temperature of the primary coolant flowing into the reactor 2, the temperature of the primary coolant flowing out of the reactor 2, and a neutron measuring device (not shown) provided inside the reactor 2. , a primary coolant flow rate, a feed water flow rate to the steam generator 4, a steam flow rate from the steam generator 4, and the like. The control device 50 generates various data including the thermal output of the nuclear reactor 2 based on these plant data. Also, the control device 50 adjusts the thermal output of the nuclear reactor 2 by controlling the controlled object. More specifically, the control device 50 increases or decreases the steam flow rate of the steam sent from the steam generator 4 to the turbine 12 by increasing or decreasing the opening degree of the steam control valve 20 as a controlled object, thereby increasing or decreasing the output of the turbine 12. and increase or decrease the thermal power of the reactor 2.

(Transition processing to rated thermal output constant operation)
In addition, the control device 50 executes constant rated thermal output operation of the nuclear power plant 1 based on an operator's instruction. The constant rated thermal power operation is an operation in which the thermal power, which is the amount of heat generated from the nuclear reactor 2, is kept constant near the rated thermal power, which is the maximum value. Constant rated thermal output operation keeps the thermal output of the nuclear reactor constant, so it is possible to increase the amount of power generated compared to constant rated electrical output operation in winter when the seawater temperature is low and power generation efficiency is high. In a state where the nuclear power plant 1 is operated with the thermal output of the nuclear reactor 2 set to a partial output smaller than the rated thermal output, the control device 50 receives an instruction from the operator to shift to rated thermal output constant operation. Execute the migration process.

FIG. 2 is an explanatory diagram showing temporal changes in the thermal output of a nuclear reactor when transitioning to constant rated thermal output operation. When the control device 50 receives an instruction from the operator to shift to the constant rated thermal output operation, the control device 50 increases the steam output at a first rate R1 until the thermal output of the nuclear reactor 2 reaches a predetermined upper limit output H1. The opening degree of the control valve 20 is increased. The first rate R1 is a general rate at which the thermal power of the reactor 2 is increased, and is a preset value. The first rate R1 is, for example, 300%/h when the rated heat output Hr is 100%. Further, the predetermined upper limit output H1 is a value set in advance as a value lower than the rated thermal output Hr, as shown in FIG. The predetermined upper limit output H1 is set to a value such that the thermal output does not exceed the rated thermal output Hr even if the thermal output is increased at the first rate R1 over the control unit time. For example, the predetermined upper limit output H1 is set to 97% or less. As a result, even if the thermal output overshoots the predetermined upper limit output H1 during stabilization of the thermal output, which will be described later, it is possible to more reliably suppress the thermal output from exceeding the rated thermal output Hr.

When the thermal output of the nuclear reactor 2 reaches the predetermined upper limit output H1 (time t1 in FIG. 2), the controller 50 stabilizes the thermal output. More specifically, when the thermal output of the nuclear reactor 2 reaches the predetermined upper limit output H1, the control device 50 temporarily stops increasing the opening of the steam control valve 20 over the first waiting time X1 and restores the current opening. to maintain. The first standby time X1 is predetermined as the time until the thermal output stabilizes when the increase in the opening degree of the steam control valve 20 is stopped from the state in which the thermal output is increased at the first rate R1. The first standby time X1 is, for example, 1 minute to 10 minutes. In FIG. 2, after the thermal output reaches the predetermined upper limit output H1, it is set to a constant value. Delay occurs. Therefore, the heat output repeatedly increases and decreases with respect to the predetermined upper limit output H1 until it is stabilized. In the following description, when the heat output is set, the increase and decrease are repeated in the same manner.

When the control device 50 stops increasing the degree of opening of the steam control valve 20 and the first standby time X1 elapses (time t2 in FIG. The subsequent processing procedure is switched depending on whether or not a request to reset the information has been made. The information when the constant rated thermal output operation was performed last time is the value of the degree of opening (control parameter) of the steam control valve 20 (controlled object). Further, the request to reset the information when the constant rated thermal output operation was performed last time is a request given in advance by the operator when it is not preferable to use the information to control the nuclear power plant 1. . A case in which it is not desirable to control the nuclear power plant 1 using information from the previous constant rated thermal output operation is, for example, a change in the rated thermal output due to seasonal differences (differences in seawater temperature), facility renewal, or the like. There may be a case where the influence of the control parameters on the thermal output of the reactor 2 is different from when the constant operation was performed last time.

(First migration process)
If the control device 50 does not have the information of the previous constant rated thermal output operation, or if the operator has requested to reset the information, the control device 50 executes the first transition process. In the first transition process, after increasing the thermal output by a predetermined value Y% at the second rate R2, the thermal output is allowed to settle for the second standby time X2, which is repeatedly executed. In other words, in the first transition process, as shown in FIG. 2, the range from the predetermined upper limit output H1 to the rated thermal output Hr is divided into a plurality of sections ΔH, and the thermal output is reduced by the predetermined value Y% for each section ΔH. After the increase, a process of settling the heat output over a second waiting time X2 is performed.

The predetermined value Y% is predetermined as at least a value equal to or lower than a rated recovery end region Ha, which will be described later. The predetermined value Y% is, for example, 0.2%. Also, the second rate R2 is predetermined as a value lower than the first rate R1. The second rate R2 is, for example, 0.5%/h. Further, the second standby time X2 is predetermined as the time until the thermal output stabilizes when the increase in the opening degree of the steam control valve 20 is stopped from the state in which the thermal output is increased at the second rate R2. be done. The second standby time X2 is longer than the first standby time X1, for example, 15 minutes to 20 minutes, in order to stabilize the heat output more reliably.

When the thermal output after stabilization reaches the rated recovery end area Ha (time t3 in FIG. 2), the control device 50 determines that the nuclear power plant 1 has returned to constant rated thermal output operation, and executes the first transition process. is stopped to keep the heat output constant. That is, the control device 50 maintains the steam control valve 20 at the current opening degree. The rated recovery end region Ha is a region lower than the rated thermal output Hr by a predetermined range. The rated recovery end region Ha (predetermined range) is set in advance as a range larger than the fluctuation (for example, 0.1%) that occurs in the thermal output when the opening degree of the steam control valve 20 as a control parameter is constant. . As a result, it is possible to more reliably prevent the thermal output that has reached the rated recovery end region Ha from exceeding the rated thermal output Hr. The rated recovery end area Ha is set, for example, within a range of 0.4% to 1% in order to provide a sufficient margin for fluctuations occurring in thermal output.

(Second transition processing)
If the control device 50 has the information of the previous constant rated thermal output operation and the operator does not request to reset the information, the control device 50 executes the second transition process. More specifically, when the control device 50 stops increasing the opening degree of the steam control valve 20 and the first standby time X1 elapses (time t2 in FIG. 2), the opening degree of the steam control valve 20 (controlled object) The thermal output is increased at the third rate R3 until the (control parameter) reaches the value when the constant rated thermal output operation was performed last time (see the two-dot chain line in FIG. 2). The third rate R3 is preset as a value lower than the first rate R1. The third rate R3 is, for example, 24%/h. Although the third rate R3 is set to a value higher than the second rate R2 in FIG. 2, the third rate R3 may be a value equal to or lower than the second rate R2. As a result, the opening degree of the steam control valve 20 is restored to the degree of opening when the constant rated thermal output operation was performed last time, so the thermal output of the reactor 2 becomes the rated thermal output.

Next, a control method for the nuclear power plant 1 according to the embodiment will be described with reference to FIG. FIG. 3 is a flowchart illustrating an example of a method for controlling a nuclear power plant according to the embodiment; In the processing procedure shown in FIG. 3, the nuclear power plant 1 is operated with the thermal output of the nuclear reactor 2 being a partial output smaller than the rated thermal output, and the operator inputs an instruction to shift to the rated thermal output constant operation. is executed by the controller 50 when the

In step S1, the control device 50 increases the opening degree of the steam control valve 20 so that the thermal output of the reactor 2 increases at the first rate R1 until the thermal output reaches the predetermined upper limit output H1. When the thermal output of the reactor 2 reaches the predetermined upper limit output H1 (time t1 in FIG. 2), the control device 50 executes stabilization of the thermal output over the first waiting time X1 as step S2. More specifically, the control device 50 stops increasing the degree of opening of the steam control valve 20 and maintains the current value of the degree of opening of the steam control valve 20 over the first waiting time X1.

Next, in step S3, the control device 50 determines whether or not there is information on the previous time when the constant rated thermal output operation was performed. As described above, in the present embodiment, the information when the constant rated thermal output operation was performed last time is the value of the control parameter of the controlled object when the constant rated thermal output operation was performed last time. It is the value of the degree of opening of the steam control valve 20 .

When the control device 50 determines that it does not have the information on the last time the constant rated thermal output operation was performed (Yes in step S3), in step S4, the thermal output is reduced by the predetermined value Y% at the second rate R2. The opening degree of the steam control valve 20 is increased so as to increase. Next, as step S5, the control device 50 performs stabilization of the thermal output over the second waiting time X2. More specifically, the control device 50 stops increasing the degree of opening of the steam control valve 20 during the second standby time X2 and maintains the degree of opening at the current value.

In step S6, the control device 50 determines whether or not the thermal output has reached the rated recovery end area Ha. When determining that the thermal output has not reached the rated recovery end area Ha (No in step S6), the control device 50 executes the processes after step S4 again. On the other hand, when the control device 50 determines that the thermal output has reached the rated recovery end area Ha (time t3 in FIG. 2) (Yes in step S6), this routine ends. As a result, the opening degree of the steam control valve 20 is maintained at the current value, and the shift to the constant rated thermal output operation is completed. As described above, in steps S4 to S6, the thermal output is increased at the second rate R2 lower than the first rate R1 until the thermal output reaches the rated recovery end region Ha, which is lower than the rated thermal output Hr by a predetermined range. After allowing the thermal power to settle, a first transition process is performed which repeats to allow the thermal output to settle for a second waiting time X2.

Further, when the control device 50 determines in step S3 that it has the information when the constant rated thermal output operation was performed last time (No in step S3), in step S7, the control device 50 performs the previous constant rated thermal output operation. Determines whether or not there is a request to reset the information at the time of execution. As described above, the request to reset the information on the previous constant rated thermal power operation was entered in advance by the operator.

If there is a request to reset the information when the constant rated thermal output operation was performed last time (No in step S7), the control device 50 executes the processing from step S4 onward. That is, in steps S4 to S6, the thermal output is increased at a second rate R2 lower than the first rate R1 until the thermal output reaches a rated recovery end region Ha lower than the rated thermal output Hr by a predetermined range. , a first transition process is performed which repeats to allow the thermal output to settle for a second waiting time X2.

If there is no request to reset the information when the constant rated thermal output constant operation was performed last time (Yes in step S7), in step S8, the control device 50 sets the opening degree (control parameter) of the steam control valve 20 (controlled object). The opening of the steam control valve 20 is increased so as to increase the thermal output at the third rate R3 until the value of the previous constant rated thermal output operation is reached. As a result, the opening degree of the steam control valve 20 is restored to the degree of opening when the constant rated thermal output operation was performed last time, so the thermal output of the reactor 2 becomes the rated thermal output, and the shift to the constant rated thermal output operation is completed. After that, the control device 50 terminates this routine.

(Action and effect of the embodiment)
As described above, the control device 50 and the control method for the nuclear power plant 1 according to the embodiment are configured so that when the thermal output of the nuclear reactor 2 is shifted to the rated thermal output constant operation in which the thermal output is the rated thermal output Hr, the thermal output is set to the rated thermal output Hr. The steam control valve 20 (controlled object) is controlled so as to increase the heat output at a first rate R1 until the predetermined upper limit output H1 lower than the heat output Hr is reached (steps S1 to S2), and the heat output reaches the predetermined upper limit output H1. When the upper limit output H1 is reached, the steam control valve 20 (controlled object) is controlled so as to increase the heat output more gently than the first rate R1 (steps S3 to S8).

With this configuration, the thermal output can be rapidly increased at the first rate R1 up to the predetermined upper limit output H1 lower than the rated thermal output Hr. Further, when the heat output reaches the predetermined upper limit output H1, the heat output is increased more slowly than at the first rate R1. Therefore, it is possible to suppress the occurrence of the overshoot of the heat output due to the control delay near the rated heat output Hr. can. Therefore, the nuclear power plant 1 can be automatically shifted to the constant rated thermal output operation while satisfactorily preventing the thermal output from exceeding the rated thermal output Hr.

Further, in the present embodiment, when the thermal output reaches the predetermined upper limit output H1, the second rate lower than the first rate R1 is maintained until the thermal output reaches the rated recovery end area Ha lower than the rated thermal output Hr by a predetermined range. After increasing the thermal output by a predetermined value Y in R2, a first transition process is executed to repeat the stabilization of the thermal output over a second waiting time X2 (steps S4 to S6).

With this configuration, the increase and settling of the heat output at the second rate lower than the first rate in the normal state are repeated step by step until the heat output reaches the rated recovery end area Ha. The overshoot of the thermal output in the section ΔH) can be suppressed even more satisfactorily. Therefore, it is possible to better prevent the thermal output from exceeding the rated thermal output.

Further, the predetermined value Y is a value equal to or less than the predetermined range of the rated recovery end area Ha. With this configuration, it is possible to prevent the thermal output from exceeding the rated thermal output when the thermal output is increased by the predetermined value Y during execution of the first transition process.

Further, in the present embodiment, when information on the degree of opening (control parameter) of the steam control valve 20 (controlled object) when the constant rated thermal output operation was performed last time is provided (No in step S3), the thermal output reaches the predetermined upper limit. When the output H1 is reached, a third rate R3 lower than the first rate R1 is applied until the degree of opening (control parameter) of the steam control valve 20 (controlled object) reaches the value when the constant rated thermal output operation was performed last time. A second transition process is executed to increase the heat output (step S8).

With this configuration, the opening degree (control parameter) when the constant rated thermal output operation was performed last time is obtained, and the thermal output is increased at the third rate R3 lower than the first rate R1. It is possible to increase the heat output to the rated heat output Hr while suppressing the overshoot satisfactorily.

If there is a request to reset the above information (No in step S7), the second transition process is not executed, and until the thermal output reaches the rated recovery end area Ha lower than the rated thermal output Hr by a predetermined range, the After increasing the heat output at a second rate R2 that is less than the one rate R1, a first transition process is performed to settle the heat output for a second waiting time X (steps S4 to S6).

With this configuration, when it is not preferable to use the information obtained when the constant rated thermal output operation was performed last time, the second transition processing is not executed, and the first transition processing is performed to shift to the constant rated thermal output operation. can be executed. As a result, it is possible to prevent the thermal output from being increased appropriately by the second transition process, and to perform the transition to the constant rated thermal output operation more appropriately.

In addition, the controlled object controls the flow rate of steam sent from the primary cooling system 100 including the reactor 2 to the secondary cooling system 200 including the turbine 12 rotated by the heat obtained by heat exchange with the primary cooling system 100. Steam control valve 20 to be regulated.

Even if the control target is the steam control valve 20 included in the secondary cooling system 200 and a control delay with respect to the thermal output of the reactor 2 is likely to occur, according to the present embodiment, the overshoot of the thermal output due to the control delay can be prevented. Its occurrence can be suppressed. Therefore, the nuclear power plant 1 can be automatically shifted to the constant rated thermal output operation while satisfactorily preventing the thermal output from exceeding the rated thermal output Hr.

Further, the nuclear power plant 1 according to the embodiment includes a primary cooling system 100 including the reactor 2, a secondary cooling system 200 including a turbine 12 rotated by heat obtained by heat exchange with the primary cooling system 100, and a control device 50 that controls a controlled object to adjust the thermal output of the nuclear reactor 2 . With this configuration, the nuclear power plant 1 can be automatically shifted to the constant rated thermal output operation while satisfactorily preventing the thermal output from exceeding the rated thermal output Hr.

In the embodiment, the process of step S7 may be omitted, and the process of step S8 may always be executed when there is information on the previous operation at a constant rated thermal output (No in step S3). Further, the processes of steps S3, S7 and S8 may be omitted, and the processes of steps S4 to S6 may be always executed after step S2.

In this embodiment, the thermal output is set (steps S2 and S5) over the first waiting time X1 and the second waiting time X2. However, the thermal output may be stabilized by monitoring the calculated value of the thermal output by the controller 50 and confirming that it has been stabilized within a predetermined fluctuation range.

Also, the controlled object may be a component included in the nuclear power plant 1 other than the steam control valve 20 as long as it can be reflected in the control of the thermal output of the nuclear reactor 2 .

1 Nuclear Power Plant 2 Nuclear Reactor 11 Steam Pipe 12 Turbine 20 Steam Regulating Valve 50 Control Device 100 Primary Cooling System (Reactor Cooling System)
200 secondary cooling system (turbine system)
300 Control system H1 Predetermined upper limit output Ha Rated recovery end area Hr Rated heat output R1 First rate R2 Second rate R3 Third rate X1 First standby time X2 Second standby time Y Predetermined value

Claims (8)

When shifting to constant rated thermal power operation in which the thermal power of the reactor is the rated thermal power, the thermal power is increased at a first rate until the thermal power reaches a predetermined upper limit lower than the rated thermal power. controlling the controlled object such that when the thermal output reaches the predetermined upper limit output, the controlled object is controlled to increase the thermal output more slowly than the first rate;
When the thermal output reaches the predetermined upper limit output, the thermal output is set at a second rate lower than the first rate until the thermal output reaches a rated recovery end region lower than the rated thermal output by a predetermined range. performing a first transition process of repeating increasing by a value and then allowing said thermal output to settle;
The control device for a nuclear power plant , wherein the predetermined value is a value equal to or less than the predetermined range of the rated recovery end region . When information on the control parameter of the controlled object when the constant rated thermal output operation was performed last time is provided, when the thermal output reaches the predetermined upper limit output, the control parameter is set to the value when the constant rated thermal output operation was performed last time. 2. The control system for a nuclear power plant according to claim 1 , wherein a second transition process is executed to increase said thermal output at a third rate lower than said first rate until reaching a value. When shifting to constant rated thermal power operation in which the thermal power of the reactor is the rated thermal power, the thermal power is increased at a first rate until the thermal power reaches a predetermined upper limit lower than the rated thermal power. controlling the controlled object such that when the thermal output reaches the predetermined upper limit output, the controlled object is controlled to increase the thermal output more slowly than the first rate;
When information on the control parameter of the controlled object when the constant rated thermal output operation was performed last time is provided, when the thermal output reaches the predetermined upper limit output, the control parameter is set to the value when the constant rated thermal output operation was performed last time. a nuclear power plant control apparatus for performing a second transition process of increasing said thermal output at a third rate lower than said first rate until reaching a value. If there is a request to reset the information, the second transition process is not executed, and a first rate lower than the first rate is maintained until the thermal output reaches a rated recovery end region lower than the rated thermal output by a predetermined range. 4. The nuclear power plant control system according to claim 2, wherein the first transition process is repeated to increase the thermal output by a predetermined value at two rates and then to stabilize the thermal output. The controlled object is a steam control that adjusts a flow rate of steam sent from a primary cooling system including the nuclear reactor to a secondary cooling system including a turbine rotated by heat obtained by heat exchange with the primary cooling system. 5. The control device for a nuclear power plant according to any one of claims 1 to 4 , which is a valve. When shifting to constant rated thermal power operation in which the thermal power of the reactor is the rated thermal power, the thermal power is increased at a first rate until the thermal power reaches a predetermined upper limit lower than the rated thermal power. controlling the controlled object such that when the thermal output reaches the predetermined upper limit output, the controlled object is controlled to increase the thermal output more slowly than the first rate;
The controlled object is a steam control that adjusts a flow rate of steam sent from a primary cooling system including the nuclear reactor to a secondary cooling system including a turbine rotated by heat obtained by heat exchange with the primary cooling system. A nuclear power plant control device that is a valve. a primary cooling system including a nuclear reactor;
a secondary cooling system including a turbine rotated by heat obtained by heat exchange with the primary cooling system;
7. A nuclear power plant control device according to any one of claims 1 to 6, which controls a controlled object to adjust the thermal output of the nuclear reactor. When shifting to constant rated thermal power operation in which the thermal power of the reactor is the rated thermal power, the thermal power is increased at a first rate until the thermal power reaches a predetermined upper limit lower than the rated thermal power. controlling the controlled object such that when the thermal output reaches the predetermined upper limit output, the controlled object is controlled to increase the thermal output more slowly than the first rate;
When the thermal output reaches the predetermined upper limit output, the thermal output is set at a second rate lower than the first rate until the thermal output reaches a rated recovery end region lower than the rated thermal output by a predetermined range. performing a first transition process of repeating increasing by a value and then allowing said thermal output to settle;
The method of controlling a nuclear power plant , wherein the predetermined value is a value equal to or less than the predetermined range of the rated recovery end region .

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