JPH05164891A - Nuclear reactor output control device - Google Patents

Abstract

PURPOSE:To shorten time required for the output of a generator to be restored when load is abruptly lowered. CONSTITUTION:The nuclear reactor output control device of this invention gives load cut-off generating signals 9 to a control rod drive control means 200 and a recirculation flow rate control means 300, allows an output to be powered down, allows output signals to be given to the control rod drive control means 200 and the recirculation flow rate control means 300 from an automatic output regulating means 100 after operating signals and the load cut-off generating signals 9 have been taken in the automatic output regulating means, controls setting output to be constant after load has been cut off, and also allows output restoring operation to automatically take place. By this constitution, setting output can be controlled to be constant after load has been abruptly lowered, restoring time can be shortened, the burden of an operator can be lowered besides, output control which allows the principal parameters of an atomic reactor to be less fluctuated, can stably be executed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reactor output device, and more particularly to a reactor output device suitable for controlling the output of a boiling water reactor.

[0002]

2. Description of the Related Art A conventional technique relating to output control when a load on a generator is suddenly reduced will be described with reference to FIG. FIG. 9 is a schematic configuration diagram of a boiling water nuclear power plant that uses an internal pump as a recirculation pump.

In FIG. 9, 1 is a reactor, 2 is a steam control valve, 3 is a turbine bypass valve, 4 is a turbine, 5 is a condenser, 6 is a generator, 7 is a water supply pump, 8 is a power load unbalance. Relay, 100 is an automatic output adjustment device, 200
Is a control rod drive control device, 201 is a motor drive control circuit, 2
Reference numeral 02 is a control rod, 300 is a recirculation flow rate control device, 301 is a variable frequency power supply device, and 302 is an internal pump.

When the load on the generator is cut off, the power load unbalance relay 8 is activated. The operation of the power load unbalance relay 8 causes the steam control valve 2 to close rapidly to prevent the turbine 4 from accelerating. In order to avoid an increase in the internal pressure of the reactor 1 due to the rapid closing of the steam control valve 2, the turbine bypass valve 3 is closed rapidly and the surplus steam is bypassed to the condenser 5. At this time, the selective control rod of the control rod 202 is rapidly inserted, and the internal pump 302 is run back to suppress the neutron rise immediately after the load is cut off, and the generator output is reduced to achieve the single load operation in the power plant. To do.

The above internal pump runback will be further described with reference to FIG. The recirculation flow rate control device 300 is configured so that the speed request signal 3
09 is output. That is, the output request signal 305 output from the main control circuit 304 based on the load request deviation signal 303 is converted into the speed request deviation signal 307 after the APRM signal 306 is subtracted. Speed controller 308
Is the speed request signal 3 based on the speed request deviation signal 307.
09 is output. The speed request signal 309 is sent to the variable frequency power supply device 301 via the changeover switch 310.
The variable frequency power supply device 301 controls the speed of the internal pump 302 based on the speed request signal 309.

On the other hand, when the generator load is cut off, the recirculation pump runback pattern calculation unit 312 inputs the reactor output signal 311 when the load is cut off, and the internal pump 30
The runback pattern information 313 of No. 2 is calculated. The internal pump runback speed signal generator 314 outputs a speed request signal 315 obtained based on the runback pattern information 313. The speed request signal 315 is transmitted to the variable frequency power supply device 301 via the changeover switch 310 which is switched by the power load unbalance relay 8 operation signal when the load is cut off. The variable frequency stagnation device 301 causes the internal pump 302 to run back based on the speed request signal 315.

[0007]

In the conventional method, an internal pump runback is performed by giving independent signals to the recirculation flow rate control device and the control rod drive control device, which are output lowering means when a sudden load decrease event occurs. And, the selection control rod was inserted into the core. In particular, when the selective control rod is inserted, the control rod may be inserted more than necessary depending on the operating point immediately before the load is suddenly reduced, so that it is difficult to control the constant set output. Therefore, in the event that the reactor output rises for some reason after the power settling, it is necessary to manually insert the control rod, which makes the operation difficult. Also, in the generator output restoration operation, the recirculation flow rate increase request operation for the recirculation flow rate control device and the control rod withdrawal for the control rod drive control device will be performed manually, so it takes a considerable time to restore the generator output. ..

An object of the present invention is to provide a reactor power control system which can shorten the time required to restore the power generator output.

[0009]

The features of the present invention include an automatic power control device for controlling reactor power, and a speed of a recirculation pump for supplying cooling water to a core based on an output signal of the automatic power control device. In a reactor output control device having a recirculation flow rate device for controlling the flow rate and a control rod drive control device for controlling the operation of control rods inserted into the core, the recirculation pump when the generator load suddenly decreases. To the recirculation pump runback signal to quickly run back the recirculation pump to the minimum speed, and also to give a signal to insert a plurality of preset selection control rods, reducing the generator output. After determining that the target output set value in the automatic output adjustment device is changed to the target output after the sudden load reduction, the automatic output control by the automatic output adjustment device is started, and the target output after the sudden load reduction is performed. Lying in reactor power control device according to claim ensured.

[0010]

[Function] When the generator load is suddenly reduced, a signal of recirculation pump runback is given to the recirculation pump to promptly rerun the recirculation pump to the minimum speed, and
After giving a signal to insert multiple selection control rods set in advance and judging that the generator output has decreased, change the target output setting value in the automatic output adjustment device to the target output after the sudden load reduction. Then, the automatic output control by the automatic output adjustment device is started to secure the target output after the sudden load reduction.Therefore, the output control from the load cut-off to the generator output restoration can be automated, and the operator's burden is significantly reduced. Can be reduced. In addition, the time required to restore the generator output can be shortened.

[0011]

1 to 5 show a reactor power control system according to an embodiment of the present invention which is applied to a boiling water reactor power plant using an internal pump as a recirculation pump. With respect to the reactor power control system according to the present embodiment, a power control method at the time of sudden load reduction will be described below by taking output control when a generator load cutoff occurs during a reactor rated operation as an example.

When it is detected by the operation of the power load unbalance relay 8 that the generator load cutoff has occurred, the power load unbalance relay 8 outputs a load cutoff generation signal 9. Since the steam control valve 2 is closed rapidly by the load cutoff generation signal 9, the acceleration of the turbine 4 is prevented. Since the turbine bypass valve 3 is rapidly opened by the load cutoff generation signal 9, the pressure increase in the reactor 1 due to the rapid closing of the steam control valve 2 is avoided. At the same time, the load cutoff generation signal 9 is also transmitted to the recirculation flow rate control device 300 to switch the internal changeover switch 310 to the a side. The speed request signal 315 output by the internal pump runback speed signal generator 314 according to the function set therein is transmitted to the variable frequency power supply device 301 via the changeover switch 310. Internal pump runback speed signal generator 31
4 generates a speed request signal 315 for performing two-stage runback of high speed and low speed. Variable frequency power supply 301
Causes the internal pump 302 to run back based on the speed request signal 315 to reduce the core flow rate. The load cutoff generation signal 9 described above is further transmitted to the control rod drive control device 200.
Entered in. Here, the load cutoff generation signal 9 switches the changeover switch 203 to the a side. This switching of the switch 203 prevents the control rod control by the control rod insertion / withdrawal request signal 215 output from the control means arithmetic circuit 209 at the time of normal start-up, and the preset control rod insertion circuit 205 at the time of sudden load reduction is set. The control rod insertion signal 216 according to the control rod pattern is output to the motor drive control circuit 201. The motor drive control circuit 201 drives the control rod drive device 217 based on the signal, and inserts the control rod 202, that is, the selection control rod into the core. As a result, the reactor output is rapidly reduced, the reactor output is reduced to near the target output immediately after the load shedding, and the primary processing after the load shedding is completed. The control signal 215 output from the control means arithmetic circuit 209 at the time of normal startup is output based on the control rod insertion / withdrawal sequence at the time of normal startup specified by the control rod value minimizer 210.
The neutron flux of the core is increased by the run-back of the internal pump 302 and the insertion of the selective control rod by this primary treatment.
As shown by the solid line in FIG. 6, it sharply decreases. In FIG. 6, the broken line shows the characteristic of the conventional example. The horizontal axis represents the elapsed time from the time when the load shedding occurred. FIG. 7 shows fluctuations in the reactor water level corresponding to the characteristics shown in FIG. 6, where the solid line shows the characteristics of this embodiment and the broken line shows the characteristics of the conventional example.

The determination circuit 118 for determining the completion of the primary processing of the automatic output adjusting device 100 is based on the input load cutoff generation signal 9 and the flow rate measured by the flow meter 303 by the determination circuit 316 of the recirculation flow rate control device 300. Based on the internal pump runback completion signal 317 that is output when it is determined that the flow rate is equivalent to the minimum flow rate, and the control rod position measured by the control rod position detector 207 by the determination circuit 206 of the control rod drive control device 200, the selected control rod is selected. The selection control rod insertion completion signal 208 output when the completion of insertion is determined is input, and the primary processing completion signal 116 is generated based on these. By this primary processing completion signal 116, the automatic output adjustment device 100
The inner changeover switch 115 is switched to the a side. The operation mode switching circuit 110 outputs a switching signal for switching the changeover switch 107 in the control calculator 106 to the side a when the load cutoff generation signal 9 is input. The changeover switch 107 is changed over to the a side by this changeover signal. The changeover switch 310 in the recirculation flow rate control device 300 is changed over to the b side by the action of the internal pump runback completion signal 317. In addition, the control rod drive control device 2
The changeover switch 203 in 00 is changed over to the b side by the action of the selection control rod insertion completion signal 208. In this state, the secondary processing for performing the recirculation flow rate control and the control rod position control by the automatic output adjustment device 100 becomes possible.

That is, the target settling output after the load is cut off, which is set in the memory 113, is the automatic output adjusting device 10.
When the changeover switch 115 in 0 is switched to the side a, the changeover switch 115 is input to the target settler 101. The adder 104 includes a target output signal 102 output by the target settler 101 based on the target selection output and an actual output equivalent signal (for example, an APRM obtained based on neutron flux signals detected by many LPRMs in the core). Signal) 103, and outputs this deviation to the control calculator 106 as an output request deviation signal 105. The control calculator 106 outputs the output request deviation signal 10
5, the control rod value is calculated, and the control rod value signal 108 corresponding to this calculation result is output. The control rod value signal 108 is transmitted to the control rod drive control device 200 because the changeover switch 107 is on the side a. In the control rod drive control device 200, the control rod value signal 108 and the output signal of the control rod value minomizer 210 are input to the control means arithmetic circuit 209. Based on these signals, the control means arithmetic circuit 209 calculates the control rod for the insertion operation. By this calculation, the control means calculation circuit 209,
First, a control rod insertion / withdrawal request signal 21 for performing an insertion operation
5 is output to the corresponding motor drive control circuit 201. The control means arithmetic circuit 209 inserts the control rod 2 so that the negative reactivity changes at a rate smaller than the rate of change of the negative reactivity introduced into the core by the insertion of the selective control rod in the primary processing. Is slowly performed (or the number of control rods to be inserted is reduced), and a control rod insertion / extraction request signal 215 is output. The motor drive control circuit 201 drives the control rod drive device 217 based on the signal to insert the control rod 202 into the core. As a result of this operation, the neutron flux reduced by the primary treatment has a small change rate of the negative reactivity injected into the core as described above.
As shown by the solid line, the tendency is to increase once, and the increased state is controlled to be almost constant. After that, that is, when about 90 seconds have elapsed from the time of occurrence of load shedding, the effect of the control rod insertion appears, and the neutron flux decreases to a predetermined value during single load operation in the power plant, and is maintained at that value thereafter. .. In this way, the secondary processing, which is the control for maintaining the reactor output at the target settling output after the load is cut off, is performed by operating the control rod. By the above control, the reactor water level is settled to a predetermined water level earlier than in the conventional example as shown in FIG.

Reactor power recovery operation is performed after the completion of the secondary treatment. This nuclear reactor power recovery operation is performed by the operator pressing the power recovery button 117 provided on the automatic power control system 100. When the output recovery button 117 is pressed, the changeover switch 115 is switched to the b side. Therefore, the target output at the time of the nuclear reactor output recovery operation set in the storage device 114 in advance is input to the target output setting device 101. The target output setter 101 outputs the target output signal 102 to the adder 104 based on this target output. The adder 104 outputs the target output signal 102 and the actual output equivalent signal 103.
And the output request deviation signal 105 is output to the control calculator 106. Also, output recovery button 11
The operation mode switching circuit 110, which has received the signal from the output recovery button 117 generated when 7 is pressed, determines that it is a reactor output recovery operation, and sets the selector switch 107 in the control calculator 106 to the a side. Switch. Control calculator 10
6 is a selection control rod insertion release signal 119 to the control rod drive control device 200 based on a signal input from the operation mode switching circuit 110 when the output restoration button 117 is pressed.
Is output. The control means arithmetic circuit 209, which has received the selection control rod insertion cancellation signal 119, cancels the insertion of the selection control rod with respect to the motor drive control circuit 201 which operates the selection control rod. After that, the control means arithmetic circuit 209 calculates the control rod for insertion operation based on the control rod value signal 108 obtained by the calculation using the output request deviation signal 105 and the output signal of the control rod value minimizer 210. .. The comparator 211 matches the control rod pattern obtained based on the axial position of the control rod detected by the control rod position detector 207 in the core axial direction with the control rod insertion / extraction sequence defined by the control rod value minimizer 210. Compare with the pattern.
The control means arithmetic circuit 209 is rearranged and the arithmetic circuit 212 is
The control rod pattern comparison result of the comparator 211 is input and rearranged into a pattern suitable for the control rod insertion / extraction sequence. After that, the control means arithmetic circuit 209 inserts the control rod based on the control rod value signal 108 obtained by the arithmetic operation using the output request deviation signal 105 and the pattern corresponding to the control rod insertion / extraction sequence rearranged by the rearrangement arithmetic circuit 212. The control rod for performing is calculated. By this calculation, the control means calculation circuit 209 first outputs the control rod insertion / withdrawal request signal 215 for performing the pulling operation to the corresponding motor drive control circuit 201. Based on the control rod insertion / extraction request signal 215, first, the inserted selection control rod is pulled out from the core. After that, the control rods other than the selective control rods are pulled out from the core. By this operation, the reactor power is increased as shown by the solid line in FIG.
This increase in power is the result of the combined use of the control rod withdrawal operation and the increase in core flow rate. That is, the determination circuit 213
However, when it is determined that the control rod withdrawal is completed, the control rod withdrawal completion signal 214 is output to the operation mode switching circuit 110 in the automatic output adjustment device 100. Operation mode switching circuit 110
Switches the changeover switch 107 in the control arithmetic unit 106 to the side b based on the control rod drawing completion signal 214. For this reason, the control calculator 106 controls the recirculation flow rate control device 300.
The flow rate increase request signal 120 is output to. The output request signal 305 output from the main control circuit 304 based on the flow rate increase request signal 120 is converted into a speed request deviation signal 307 after the APRM signal 306 is subtracted. The speed controller 308 outputs a speed request signal 309 based on the speed request deviation signal 307. Speed request signal 309
Is the variable frequency power supply 3 via the changeover switch 310.
Sent to 01. The variable frequency power supply device 301 controls the speed of the internal pump 302 based on the speed request signal 309. In this way, the reactor output is restored to the target output. In FIG. 8, the broken line is for the conventional example.

In the present embodiment, the operation in the reactor power recovery operation can be automated, and the burden on the operator in this operation can be reduced. Also, the time required for the reactor power recovery operation can be shortened.

In this output restoration operation, after the control rods are rearranged into a pattern suitable for the control rod insertion / extraction sequence, the signals used for the judgment in the operation mode switching circuit 110 and the output setting in the operation mode switching circuit 110 are set. It is possible to freely switch the changeover switch 107 by providing some stored memory devices and combining them, and it is also possible to recover with the optimum operating characteristics.

Further, the load cutoff generation signal 9 is stopped from being directly input to the control rod drive control device 200 and the recirculation flow rate control device 300, and is input only to the automatic output adjusting device 100
If a signal for internal pump runback and selection control rod insertion is output from this device, it is possible to perform a series of operations from output reduction to output restoration after load interruption occurs only by supporting the automatic output adjustment device. Further, if the value in the storage device 114 can be set from the outside, it is possible to restore an arbitrary output.

The above is the output control method when the turbine bypass valve operates due to load shedding, but in the unlikely event that the turbine bypass valve does not operate, as shown in FIG. At the same time, a recirculation pump trip is performed to ensure reactor safety.

[0020]

According to the present invention, it is possible to automatically perform from the output reduction operation after the sudden load reduction to the generator output recovery operation, and the burden on the operator can be reduced. In addition, the time required for the reactor power recovery operation can be shortened.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a reactor power control system according to a preferred embodiment of the present invention.

FIG. 2 is a detailed configuration diagram of the automatic output adjustment device in FIG.

FIG. 3 is a detailed configuration diagram of the control rod drive control device of FIG.

FIG. 4 is a detailed configuration diagram of the recirculation flow rate control device of FIG.

FIG. 5 is an explanatory diagram showing an outline of an output control method.

FIG. 6 is a characteristic diagram showing changes in neutron flux after load shedding.

FIG. 7 is a characteristic diagram showing changes in reactor water level after load shedding.

FIG. 8 is a characteristic diagram showing a change in generator output due to a reactor output restoration operation.

FIG. 9 is a configuration diagram of a conventional reactor power control device.

FIG. 10 is a detailed configuration diagram of the recirculation flow rate control device of FIG. 9.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Reactor, 2 ... Steam control valve, 2 ... Turbine bypass valve, 9 ... Load cutoff generation signal, 100 ... Automatic output adjusting device, 200 ... Control rod drive control device, 202 ... Control rod, 3
00 ... Recirculation flow controller, 302 ... Internal pump.

Claims (4)

[Claims] 1. An automatic power control device for controlling reactor power, a recirculation flow rate device for controlling the speed of a recirculation pump for supplying cooling water to the core based on an output signal of the automatic power control device, and a core. In a reactor power control device having a control rod drive control device for controlling operation of a control rod inserted therein, a signal of a recirculation pump runback to the recirculation pump when the generator load suddenly decreases. And quickly recirculate the recirculation pump to the minimum speed,
After giving a signal to insert a plurality of selection control rods set in advance and determining that the generator output has decreased, the target output set value in the automatic output adjustment device is set as the target output after the sudden load reduction. A reactor output control device, which is changed to start automatic output control by the automatic output adjustment device to secure a target output after a sudden load reduction. 2. The output control device directly takes in the detected generator load sudden decrease signal to the recirculation flow rate control device and the control rod drive control device, and outputs the output signals of the recirculation flow rate control device and the control rod drive control device. The reactor power control device according to claim 1, wherein the automatic power control device controls the recirculation flow rate and the control rod position until the output is restored to the output after the load is cut off. 3. In the output control device, when the target output setting in the automatic output adjustment device is changed to the target output after the generator output is restored, the automatic output adjustment device controls the control rod drive control device. A control rod withdrawal command is given, the control rod that is in the inserted state after the load is suddenly reduced is automatically operated, and the control rod is automatically pulled out in accordance with the sequence after the specified control rod pattern is secured. 2. The reactor output control apparatus according to claim 1, wherein a flow rate increase command is given to automatically increase the speed of the recirculation pump operating at the minimum speed after the load is suddenly reduced to achieve a target generator output. 4. In the output control device, when the generator load suddenly decreases and the turbine bypass valve operates, the recirculation pump is run back, the generator load suddenly decreases, and the turbine bypass valve operates. The reactor power control system according to claim 3, wherein if not, the recirculation pump is tripped.