JPH07225296A - Nuclear reactor power controller - Google Patents

Abstract

PURPOSE:To provide a nuclear reactor power controller a which can suppress rising of a neutron flux is suppressed and avoid an unnecessary scram in the case of an intermediate and small earthquakes by which a nuclear reactor equipment is sound. CONSTITUTION:A nuclear reactor power controller controls power by inserting or removing a control rod into or from a core 3 of a nuclear reactor by a control rod driver, and comprises measuring means 24 for measuring an earthquake acceleration, deciding means 25 for deciding that the acceleration measured by the means 24 exceeds a threshold value, and means 26 for reducing power by inserting the partial rod based on the decision of the means 25 when the acceleration exceeds a decided value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reactor power control system for performing appropriate power control such as continuous specified power operation when a weak earthquake that does not affect the reactor structure occurs.

[0002]

2. Description of the Related Art In a boiling water reactor, heat generated from a fuel is transferred to cooling water, and the cooling water boils, so that steam bubbles are constantly generated in the core. In such heat generation state, the power output of the reactor can be controlled by the following three methods.

1) Cooling water flows from the lower part to the upper part of the core by a recirculation pump, and the frequency of nuclear fission in the core is controlled by adjusting the flow rate of this cooling water (hereinafter referred to as core flow rate). can do. Therefore,
The power of the reactor can be controlled by adjusting the speed of the recirculation pump.

2) Further, since the control rod is inserted from the lower part of the core and the position of the control rod is adjusted to control the amount of neutrons in the core, the control rod driving device adjusts the position in the core to output power. Can be controlled.

3) Furthermore, by opening the main steam control valve and the turbine bypass valve, the reactor pressure can be lowered and the reactor power can be lowered. That is, the steam bubbles generated in the core are separated from the cooling water by the steam separator located above the core, and then flow through the main steam pipe to the turbine through the main steam control valve. Here, for example, when the main steam control valve is opened, the flow rate of steam flowing out from the reactor increases, the pressure in the core decreases, and the proportion of steam bubbles increases. As the number of vapor bubbles increases, the frequency of nuclear fission is suppressed and the reactor power decreases. Therefore, heat generation from the fuel is reduced, the increase of vapor bubbles is suppressed, and the output is low and stable.

In addition to controlling the output of the nuclear reactor of the above 1) to 3), when the neutron flux rises and exceeds the set value of 120%, the nuclear reactor is stopped. Further, a time constant is added to the neutron flux signal to calculate a surface heat flux equivalent signal, and when the surface heat flux equivalent signal exceeds a set value, the reactor is stopped.

[0007]

In the case of a large earthquake, a reactor scrum with a large seismic acceleration is set, and the reactor automatically shuts down, but in the case of an earthquake whose seismic intensity is not so large, The equipment and system inside the reactor building are oscillating, and it is conceivable that steam bubbles in the core decrease or the output rises due to changes in the reactor state.

In the boiling water reactor, there is the above power control method, but in the interlock, when a small and medium-sized earthquake occurs and the neutron flux rises, if the neutron flux rises to the high scrum set point (120%). Scrum as it is.

The reactor is automatically stopped by scramming, and there is no safety problem because it is a natural phenomenon and not a failure of reactor equipment.

[0010] However, in particular, stopping the reactor while the reactor equipment is not in failure causes a decrease in operating rate and may impair the stable supply of electric power.

The present invention has been made based on such a situation, and an atom capable of suppressing an increase in neutron flux and avoiding an unnecessary scrum in a small-to-medium-scale earthquake where the reactor equipment is healthy. An object is to provide a furnace power control device.

[0012]

In order to achieve the above-mentioned object, the invention according to claim 1 is a reactor power for performing power control by inserting / removing a control rod into / from a reactor core by a control rod drive device. In the control device, a measuring means for measuring the seismic acceleration, a judging means for judging that the seismic acceleration measured by the measuring means exceeds a threshold value, and the seismic acceleration is a judgment value based on the judgment of the judging means. And a means for reducing the output by inserting a part of the control rods.

According to a second aspect of the present invention, a reactor output capable of controlling output by a recirculation pump and a recirculation flow rate control device having a recirculation pump speed control device for recirculating coolant to the reactor core. In the control device, a measuring means for measuring the seismic acceleration, a judging means for judging that the seismic acceleration measured by the measuring means exceeds a threshold value, and the seismic acceleration is a judgment value based on the judgment of the judging means. And a means for reducing the output of the reactor by decreasing the recirculation pump speed when the temperature exceeds the limit. 4. The invention according to claim 3, wherein the coolant is recirculated to the core of the reactor. Measurement to measure seismic acceleration in a reactor power control system that enables output control by a recirculation pump and a recirculation flow rate control system equipped with a recirculation pump speed control system Means, a judging means for judging that the seismic acceleration measured by the measuring means exceeds a threshold value, and the recirculation pump is stopped when the seismic acceleration exceeds the judgment value based on the judgment of the judging means. And a means for reducing the output of the nuclear reactor.

According to a fourth aspect of the present invention, a reactor output control device having a main steam control valve, a turbine bypass valve, a main steam relief safety valve, and a pressure adjusting device for operating these in a main steam system from a reactor to a turbine. In the above, the measuring means for measuring the seismic acceleration, the judging means for judging that the seismic acceleration measured by the measuring means exceeds the threshold value, and the seismic acceleration exceeds the judging value based on the judgment of the judging means. In this case, a means for decreasing the output of the nuclear reactor by increasing the opening degree of the main steam control valve is provided.

According to a fifth aspect of the present invention, a reactor output control device having a main steam control valve, a turbine bypass valve, a main steam relief safety valve, and a pressure adjusting device for operating them in a main steam system from a reactor to a turbine. In the above, the measuring means for measuring the seismic acceleration, the judging means for judging that the seismic acceleration measured by the measuring means exceeds the threshold value, and the seismic acceleration exceeds the judging value based on the judgment of the judging means. In this case, a means for reducing the output of the nuclear reactor by opening the turbine bypass valve is provided.

According to a sixth aspect of the present invention, a reactor output control device having a main steam control valve, a turbine bypass valve, a main steam relief safety valve, and a pressure adjusting device for operating these in a main steam system from a reactor to a turbine. In the above, the measuring means for measuring the seismic acceleration, the judging means for judging that the seismic acceleration measured by the measuring means exceeds the threshold value, and the seismic acceleration exceeds the judging value based on the judgment of the judging means. In this case, a means for reducing the output of the nuclear reactor by opening the main steam relief safety valve is provided.

According to a seventh aspect of the present invention, a neutron flux detector is provided in the core of the nuclear reactor, and when the neutron flux detector detects a neutron flux height of a certain value or more, the reactor output for scramming the reactor. In the control device, a measuring means for measuring the seismic acceleration, a judging means for judging that the seismic acceleration measured by the measuring means exceeds a threshold value, and the seismic acceleration is a judgment value based on the judgment of the judging means. It is characterized by having a means for bypassing the high neutron flux high scrum when it exceeds.

According to an eighth aspect of the present invention, a neutron flux detector is provided in the core of a nuclear reactor, and when the neutron flux detector detects a neutron flux height higher than a certain value, the reactor output for scramming the reactor. In the control device, a measuring means for measuring the seismic acceleration, a judging means for judging that the seismic acceleration measured by the measuring means exceeds a threshold value, and the seismic acceleration is a judgment value based on the judgment of the judging means. If the neutron flux signal is exceeded, a means for performing a filter setting or other arithmetic processing on the neutron flux signal is provided.

According to a ninth aspect of the present invention, a neutron flux detector is provided in the core of the nuclear reactor, and when the neutron flux detector detects a neutron flux height higher than a certain value, the reactor output is stopped. In the control device, a measuring means for measuring the seismic acceleration, a judging means for judging that the seismic acceleration measured by the measuring means exceeds a threshold value, and the seismic acceleration is a judgment value based on the judgment of the judging means. And a means for increasing the neutron flux signal set value for stopping the nuclear reactor when the value exceeds the predetermined value.

According to a tenth aspect of the present invention, a neutron flux detector is provided in the core of the nuclear reactor, and when the neutron flux detector detects a neutron flux height higher than a certain value, the reactor output for scramming the reactor. In the control device, a measuring unit that measures the seismic acceleration, a determining unit that determines that the seismic acceleration measured by the measuring unit exceeds a threshold value,
Based on the judgment of this judgment means, a means for stopping the reactor is provided when both the neutron flux high signal and the surface heat flux equivalent signal are satisfied when the seismic acceleration exceeds the judgment value. .

The invention described in claim 11 is from claim 1 to claim 1.
The reactor power control apparatus described up to 0 is characterized in that the means for measuring the seismic acceleration is provided with seismic acceleration measuring means for measuring at a point distant from the reactor.

The invention according to claim 12 is from claim 1 to claim 1.
0 in the reactor power control device described above, in addition to means for measuring seismic acceleration, means for outputting a signal to the determination means when a signal such as acceleration or displacement of equipment in a nuclear power plant exceeds a threshold value It is characterized by having.

[0023]

According to the present invention, when the earthquake occurs, the seismic acceleration and the signal increase of various equipment are detected to reduce the reactor output or change the reactor shutdown signal to avoid unnecessary reactor shutdown. can do.

That is, according to the inventions of claims 1 to 6,
When an earthquake is detected, the output is reduced by inserting some control rods, the output is reduced by reducing the recirculation pump speed, and the output is reduced by stopping the recirculation pump. The output can be reduced by increasing the opening degree of the steam control valve, and can be reduced by opening the main steam relief safety valve.

According to the present invention, the neutron flux height (eg: 120%) signal is bypassed at the time of earthquake determination, a filter is installed on the neutron flux signal, and the atom based on the neutron flux signal is used. Set the furnace stop set value to, for example, 120
By setting it to%, the shutdown of the reactor can be avoided.

According to the tenth aspect of the present invention, when the neutron flux height (for example, 120%) signal and the surface heat flux equivalent signal obtained by performing arithmetic processing on the neutron flux signal exceed the set values at the time of the earthquake determination. An interlock that shuts down the reactor when both of the signals are established can be installed to avoid unnecessary shutdown of the reactor.

According to the eleventh and twelfth aspects of the invention, not only the accelerometer in the nuclear power plant but also the measuring means is used.
By using an accelerometer at a location distant from the nuclear power plant or an accelerometer or a displacement gauge of various equipment in the nuclear power plant, it is possible to make an earthquake judgment when these signals exceed a set value.

[0028]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram showing a system and a reactor power control device in a natural circulation type boiling water reactor.

The reactor containment vessel 1 is installed in the reactor building, and the reactor pressure vessel 2 is installed in the reactor containment vessel 1 on the pedestal.

A reactor core 3 is installed in the reactor pressure vessel 2, and a recirculation pump 4 for cooling the reactor core 3 is also installed. The core 3 is composed of a plurality of fuel assemblies (not shown), control rods 5 which can be inserted and removed, and the like. The coolant is heated by the nuclear reaction heat of the core 3 to be in a two-phase state of water and steam. Circulate above 3.

Then, the steam flows into a steam dryer (not shown) above the core 3 to become dry steam, and the reactor pressure vessel 2
Is fed to a steam turbine 8 via a main steam pipe 7 connected to the upper part of the.

On the other hand, the water separated from the steam in the reactor pressure vessel 2 flows down to the cooling water below the core 3 via the jet pump 6, is guided to the lower part of the core 3 again, and then rises. Recirculate in the core 3.

Main steam isolation valves 9 and 10 are inserted before and after the main steam pipe 7 passes through the reactor containment vessel 1,
Further, a main steam stop valve 11 and a main steam control valve 12 are sequentially inserted between the main steam isolation valve 10 and the steam turbine 8. Then, the steam fed to the steam turbine 8 drives the steam turbine 8, and the generator 13 rotates to generate electric power.

The steam that has driven the steam turbine 8 is condensed in a condenser 14 installed below the steam turbine 8 to be condensed water. This condensate is again introduced into the reactor pressure vessel 2 via the condensate pump 15, the feed water heater 16, and the feed water pump 17, and is fed below the core 3.

On the other hand, the main steam isolation valve 10 and the main steam stop valve 1
1, a turbine bypass pipe 18 is arranged between the main steam pipe 7 and the condenser 14, and a turbine bypass valve 19 is inserted in the turbine bypass pipe 18.

A main steam relief safety valve 20 is connected to an inlet side of the main steam isolation valve 9 of the main steam pipe 7 in the reactor containment vessel 1, and a main steam relief pipe 21 is connected to the main steam relief safety valve 20. And extends downward. The lower end of the main steam release pipe 21 is the pool water 2 of the pressure suppression chamber 22 as a suppression pool provided at the bottom of the reactor pressure vessel 2.
It is immersed in 3.

In this embodiment, in this embodiment, measuring means (for example, an earthquake (acceleration) meter) 2 for measuring seismic acceleration is used.
4 and determination means (determination device) for determining that the seismic acceleration measured by the measurement means 24 exceeds a threshold value
25, based on the judgment of the judging means 25, when the seismic acceleration exceeds the judgment value (set value (g ₀ )), the control rod is inserted, the recirculation pump speed is decreased or stopped, and the main steam control valve opening is increased. , Turbine bypass valve open, main steam relief safety valve open,
Means 26 for reducing the reactor output by bypassing the high neutron flux high scrum, calculation such as installing a filter on the neutron flux signal, or raising the neutron flux signal set value is provided.

FIG. 2 is a reactor characteristic diagram showing changes in neutron flux and changes in surface heat flux when the voids in the reactor disappear or the state of the reactor changes when an earthquake occurs.

Although the increase in neutron flux may reach the reactor shutdown set value of 120% due to an earthquake, the neutron flux decreases due to the occurrence of voids in the reactor due to the increase in output, and the behavior during an earthquake is 1-2 seconds. The surface heat flux increase is 2 ~
It is 3%, and there is no problem with the integrity of the fuel rod. When a larger earthquake occurs, the reactor scram interlock is activated due to the large earthquake acceleration, and the reactor is shut down. This embodiment avoids unnecessary reactor scram when an earthquake occurs that does not reach the scrum due to the large earthquake acceleration.

FIG. 3 is a logic block diagram showing the interlock of the present invention, and FIG. 4 is a graph showing an earthquake waveform. An earthquake determination signal is output when the earthquake acceleration exceeds the set value g ₀ . This set value g ₀ is set to a value smaller than the large seismic acceleration of 200 gal when the reactor is stopped. In the case of a normal earthquake, there is an initial tremor before the main sway of the quake as shown in FIG.

It is desirable that the earthquake determination signal be output 2-3 seconds before the following operation for suppressing the increase in neutron flux during an earthquake.

The operation logic of FIG. 3 is activated by the determination signal.

(1) First, in order to reduce the reactor output, some of the selected control rods 5a are inserted (S1). (2) By reducing the speed of the recirculation pump 4, the voids in the reactor are increased and the reactor output is decreased (S2). (3) The recirculation pump 4 is stopped to reduce the reactor output (S3). (4) Increasing the opening degree of the main steam control valve 12 (S
4), (5) Open the turbine bypass valve 19 (S
5), and (6) Opening the main steam relief safety valve 20 (S6)
As a result, the reactor pressure is lowered, voids in the reactor are generated, and the reactor power is reduced.

By thus reducing the reactor output from the rated output, it is possible to prevent the reactor from stopping even if the neutron flux rises when an earthquake occurs.

As another means, (7) an interlock that bypasses the neutron flux high scrum is provided by the earthquake determination signal (S7).

This is activated only during an earthquake, but as mentioned above, the event is short during an earthquake and the rise in surface heat flux is 2-3.
%, And there is no problem with fuel integrity.

(8) The neutron flux signal is subjected to arithmetic processing (filter installation, etc.) using the earthquake determination signal (S8). (9) 120% setting of neutron flux signal by seismic judgment signal
This is done (S9). (10) In addition to the neutron flux high scrum, the surface heat flux is also set by the earthquake determination signal, and the reactor is stopped only when both exceed the set value (eg, 105%) (S10).

FIGS. 5 and 6 show another embodiment of the decision device. Earthquake (acceleration) meters A to D are installed at points several kilometers away from the nuclear power plant, and when the accelerometer exceeds a set value, an earthquake determination signal is output. When a seismic wave is transmitted from a distance, seismic judgment is performed prior to shaking of the nuclear power plant. Also in this case, the operation logic is activated as shown in FIG.

FIG. 7 shows an embodiment of still another judging device. An accelerometer, a displacement meter, or the like provided in various devices in a nuclear power plant is used, and an earthquake determination signal is output when these measured values exceed set values. Also in this case, the operation logic is activated as shown in FIG.

According to the present embodiment described above, when an earthquake occurs, the seismic acceleration and the rise of signals of various devices are detected to reduce the reactor output or change the reactor stop signal to eliminate unnecessary reactors. Stops can be avoided.

That is, the operations (1) to (6) of the logic described above.
Therefore, when an earthquake is determined, the output is reduced by inserting some control rods 5a, the output is reduced by reducing the speed of the recirculation pump 4, and the output is stopped by stopping the recirculation pump 4. It is possible to decrease the output by decreasing the output of the main steam control valve 12, opening the main steam release safety valve 20, and the like.

Further, by the operations (7) to (9) of the logic, the neutron flux height (120%) signal is bypassed at the time of earthquake determination, the filter is installed on the neutron flux signal, and the atom by the neutron flux signal is detected. Set the furnace shutdown setting value to 12
By setting it to 0%, the shutdown of the reactor can be avoided.

Further, by the logic operation (10), at the time of earthquake judgment, the neutron flux height (120%) signal and the surface heat flux equivalent signal obtained by arithmetic processing of the neutron flux signal are set to the set value (10).
(5%) is exceeded, an interlock that shuts down the reactor can be installed only when both of the signals are satisfied to avoid unnecessary shutdown of the reactor.

According to the eleventh and twelfth aspects of the invention, not only the accelerometer in the nuclear power plant but also the measuring means is used.
By using an accelerometer at a location distant from the nuclear power plant or an accelerometer or a displacement gauge of various equipment in the nuclear power plant, it is possible to make an earthquake judgment when these signals exceed a set value.

[0056]

As described above, according to the present invention, an earthquake is preliminarily determined by the installation of the measuring means, the determining means, and the means for operating each device, the reactor output is reduced, and the neutron during the earthquake It is possible to avoid a reactor shutdown due to the ascent, and to avoid unnecessary reactor shutdowns by changing the reactor scrum logic due to the neutron flux height during an earthquake. The effect of is played.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram illustrating a reactor and a reactor power control device for explaining an embodiment according to the present invention.

FIG. 2 is a characteristic diagram showing a change in reactor output when an earthquake occurs.

FIG. 3 is a logic configuration diagram in this embodiment.

FIG. 4 is an earthquake determination signal diagram in this embodiment.

FIG. 5 is a view showing another embodiment of the present invention, showing a state of installation of a seismograph.

6 is an earthquake determination signal diagram showing the operation of the embodiment shown in FIG.

FIG. 7 is an earthquake determination signal diagram showing still another embodiment of the present invention.

[Explanation of symbols]

 1 Reactor Containment Vessel 2 Reactor Pressure Vessel 3 Core 4 Recirculation Pump 5 Control Rod 5a Selection Control Rod 6 Jet Pump 7 Main Steam Pipe 8 Steam Turbine 9,10 Main Steam Isolation Valve 11 Main Steam Stop Valve 12 Main Steam Control Valve 13 Generator 14 Condenser 15 Condensate Pump 16 Feed Water Heater 17 Water Pump 18 Turbine Bypass Pipe 19 Turbine Bypass Valve 20 Main Steam Relief Safety Valve 21 Main Steam Relief Pipe 22 Pressure Suppression Chamber 23 Pool Water 24 Measuring Means 25 Judgment Means 26 Means (for lowering output)

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Hiroshi Ono 8 Shinsugita-cho, Isogo-ku, Yokohama-shi, Kanagawa Stock company, Toshiba Yokohama Works (72) Inventor Akira Kojima, 8 Shinsita-cho, Isogo-ku, Yokohama-shi, Kanagawa Company Toshiba Yokohama Office

Claims (12)

[Claims] 1. A reactor output control device for performing output control by inserting / removing a control rod into / from a reactor core by a control rod driving device, and measuring means for measuring seismic acceleration, and the measuring means. Determination means for determining that the seismic acceleration exceeds a threshold value, and means for reducing the output by inserting some control rods when the seismic acceleration exceeds the determination value based on the determination of the determination means. A reactor output control device comprising: 2. A reactor output control device capable of output control by a recirculation flow rate control device equipped with a recirculation pump for recirculating coolant in a reactor core and a recirculation pump speed control device, wherein seismic acceleration The measuring means for measuring, the judging means for judging that the seismic acceleration measured by this measuring means exceeds the threshold value, and the re-determination based on the judgment of this judging means when the seismic acceleration exceeds the judgment value. And a means for reducing the output of the reactor by lowering the circulation pump speed. 3. A reactor output control device capable of output control by a recirculation flow rate control device equipped with a recirculation pump for recirculating coolant to a reactor core and a recirculation pump speed control device, wherein seismic acceleration The measuring means for measuring, the judging means for judging that the seismic acceleration measured by this measuring means exceeds the threshold value, and the re-determination based on the judgment of this judging means when the seismic acceleration exceeds the judgment value. And a means for reducing the output of the reactor by stopping the circulation pump. 4. A main steam system from a reactor to a turbine,
In a reactor power control device having a main steam control valve, a turbine bypass valve, a main steam relief safety valve and a pressure adjusting device for operating these, a measuring means for measuring seismic acceleration and a seismic acceleration measured by this measuring means A judgment means for judging that the threshold value has been exceeded, and based on the judgment of this judgment means, when the seismic acceleration exceeds the judgment value, the opening of the main steam control valve is increased to decrease the output of the reactor. A nuclear reactor power control device comprising: 5. The main steam system from the reactor to the turbine,
In a reactor power control device having a main steam control valve, a turbine bypass valve, a main steam relief safety valve and a pressure adjusting device for operating these, a measuring means for measuring seismic acceleration and a seismic acceleration measured by this measuring means A judgment means for judging that the threshold value is exceeded, and a means for reducing the output of the reactor by opening the turbine bypass valve when the seismic acceleration exceeds the judgment value based on the judgment of the judgment means A reactor power control device characterized by the above. 6. A main steam system from a reactor to a turbine,
In a reactor power control device having a main steam control valve, a turbine bypass valve, a main steam relief safety valve and a pressure adjusting device for operating these, a measuring means for measuring seismic acceleration and a seismic acceleration measured by this measuring means A determination means for determining that the threshold value is exceeded, and means for reducing the output of the reactor by opening the main steam relief safety valve when the seismic acceleration exceeds the determination value based on the determination of the determination means A reactor power control device characterized by the above. 7. A neutron flux detector is provided in the core of a nuclear reactor,
In the reactor power control device that scrams the reactor when a neutron flux height above a certain value is detected by this neutron flux detector, the measuring means for measuring seismic acceleration and the seismic acceleration measured by this measuring means are Reactor characterized by comprising a judging means for judging that the threshold value has been exceeded, and means for bypassing the neutron flux high scrum when the seismic acceleration exceeds the judgment value based on the judgment of the judging means. Output control device. 8. A neutron flux detector is provided in the core of a nuclear reactor,
In the reactor power control device that scrams the reactor when a neutron flux height above a certain value is detected by this neutron flux detector, the measuring means for measuring seismic acceleration and the seismic acceleration measured by this measuring means are A means for determining that the threshold value is exceeded, and a means for performing a filter setting or other arithmetic processing on the neutron flux signal when the seismic acceleration exceeds the determination value based on the determination of the determination means Characteristic reactor power control device. 9. A neutron flux detector is provided in the core of a nuclear reactor,
In the reactor power control device that shuts down the reactor when a neutron flux height above a certain value is detected by this neutron flux detector, the measuring means for measuring seismic acceleration and the seismic acceleration measured by this measuring means are Judgment means for judging that the threshold has been exceeded, and based on the judgment of this judgment means, the neutron flux signal set value for stopping the reactor when the seismic acceleration exceeds the judgment value is set to the above-mentioned fixed value or more. A reactor power control device comprising means. 10. A reactor power control apparatus for providing a neutron flux detector in the core of a nuclear reactor, and scramming the reactor when a neutron flux height of a certain value or more is detected by the neutron flux detector. And a determination means for determining that the seismic acceleration measured by this measuring means exceeds a threshold value, and a neutron when the seismic acceleration exceeds the determination value based on the determination by this determining means. A reactor output control device comprising means for stopping the reactor when both the bundle height signal and the surface heat flux equivalent signal are satisfied. 11. The reactor power control apparatus according to claim 1, further comprising seismic acceleration measuring means for measuring a seismic acceleration at a point distant from the reactor. Reactor power control device. 12. The reactor power control apparatus according to claim 1, wherein, in addition to the means for measuring seismic acceleration, a signal such as acceleration or displacement of equipment in a nuclear power plant exceeds a threshold value. A reactor output control device, characterized in that the determination means is provided with means for outputting a signal.