JPH08262185A - Reactor output control device - Google Patents

Abstract

PURPOSE: To provide a reactor output control device which detects the small vibration of a reactor due to the preliminary tremor of an earthquake, suppresses the tentative increase in the neutron flux by controlling a control rod or a rector flow, and suppresses the stop of the reactor or output decrease by avoiding an unneeded scrum when the earthquake is in small to medium scale. CONSTITUTION: A reactor output control device is provided with a control rod drive mechanism 7 for controlling a control rod position in a reactor and a reactor core flow control device 5 for controlling the reactor core flow. It is provided with a reactor control device 30 consisting of an earthquake detector 31 for detecting the occurrence and extinction of an earthquake and a reactor control device 32 for outputting an earthquake detection signal S1 from the earthquake detector 31 and a control rod operation signal S4 and a reactor flow control signal S3 according to a reactor core 3 and plant information.

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 capable of avoiding an emergency stop and power reduction at the time of an earthquake in a nuclear power plant.

[0002]

2. Description of the Related Art In a conventional nuclear power plant, a boiling water reactor is taken as an example, and as shown in the schematic configuration diagram of the nuclear power plant of FIG. In this reactor containment vessel 1, a reactor pressure vessel 2 is installed on a pedestal. A reactor core 3 is installed in the reactor pressure vessel 2, and further the reactor core 3
Recirculation pump 4 for circulating the coolant for cooling the
A core flow rate control device 5 is also installed.

The core 3 includes a plurality of fuel assemblies (not shown), a control rod 6 which can be inserted into and pulled out from the core 3, and a selection control rod 6a for adjusting power and a control rod drive mechanism 7 which are part of the control rod 6. A reactor output control device (not shown) that inputs information from these devices and controls the output of the reactor to a predetermined set value.

The coolant in the reactor pressure vessel 2 is heated to a high temperature by the reaction heat of nuclear fission in the core 3 and flows in a two-phase flow state of water and steam to the upper side of the core 3. The steam of which is not shown. After passing through the steam separator, it enters the steam dryer to become dry steam, and is fed to the steam turbine 9 via the main steam pipe 8 connected to the upper part of the reactor pressure vessel 2.

On the other hand, the water separated from the steam by the steam separator in the reactor pressure vessel 2 passes through the jet pump 10 and the core 3
Of the core 3 and is guided to the lower part of the core 3 again.
Reflux into. Further, main steam isolation valves 11 and 12 are inserted in the main steam pipe 8 before and after the penetration portion of the reactor containment vessel 1, and further, between the main steam isolation valve 12 and the steam turbine 9. A steam stop valve 13 and a main steam control valve 14 are sequentially inserted, and the steam fed to the steam turbine 9 drives the steam turbine 9 to rotate a generator 15 to generate electricity.

The steam driving the steam turbine 9 is condensed in a condenser 16 installed below the steam turbine 9 to be condensed water, and this condensed water is condensed by a condensate pump 17 and a feed water heater 1.
8. Reintroduced into the reactor pressure vessel 2 via the water supply pump 19, and water is supplied below the reactor core 3. On the other hand, a turbine bypass pipe 20 is arranged between the main steam pipe 8 between the main steam isolation valve 12 and the main steam stop valve 13 and the condenser 16, and the turbine bypass pipe 20 is connected to the turbine bypass pipe 20. Is a turbine bypass valve
21 is inserted.

Further, a main steam relief safety valve 22 is provided on the main steam pipe 8 in the reactor pressure vessel 2 at the inlet side of the main steam isolation valve 11.
This main steam relief safety valve 22 is connected to the main steam relief pipe.
23 is connected, the lower end of which is a pressure suppression chamber as a suppression pool provided at the bottom of the reactor pressure vessel 2.
It is immersed in 24 pool water 25.

In the nuclear power plant configured as described above, in order to ensure stable operation of the equipment, prevent damage to the core 3 and each equipment constituting the reactor, and ensure the safety of the reactor, A control system for controlling the output of the core 3 during abnormal operation of the nuclear reactor has been constructed.

Particularly in a nuclear reactor, it is important from the viewpoint of soundness of reactor equipment and safety of the reactor to suppress abrupt changes in core heat output. Safety measures are taken to shut off the core heat output when an abnormal change in the output, that is, the neutron flux in the core 3, is detected. A boiling water reactor, for example, has the following characteristics (1) to (4).

(1) When the fuel temperature rises, the output decreases,
Conversely, when the fuel temperature decreases, the heat output increases (Doppler effect). (2) When the vapor volume ratio of the core 3, that is, the void rate increases, the heat output decreases, and conversely, when the void rate decreases, the output increases (coolant density effect).

(3) When the temperature of the coolant increases, the heat output decreases, and conversely, when the temperature of the coolant decreases, the heat output increases (coolant temperature effect). (4) The heat output decreases when the neutron absorber is put in the core, and conversely, the heat output rises when the neutron absorber is taken out of the core 3.

Therefore, the output (neutron flux) of the boiling water reactor can be adjusted by combining the above (1) to (4). Specifically, in the reactor power control device, during the rated output operation by the following operation,
Alternatively, the output of the reactor is controlled during abnormal operation.

First, the coolant flows from the lower part to the upper part in the core 3 by the recirculation pump 4 provided inside or outside the reactor pressure vessel 2. It is possible to control the frequency of fission in the core 3 by adjusting the flow rate). Therefore, the output of the nuclear reactor can be controlled by adjusting the flow rate of the recirculation pump 4 by the core flow rate control device 5.

The control rod 6 and the output control selection control rod 6a are inserted into the core 3, and the position of the control rod 6 is adjusted to control the amount of neutrons in the core 3. The power can be controlled by adjusting the positions of the control rods 6 and 6a in the core 3.

Further, by opening the main steam control valve 14 and the turbine bypass valve 21, the reactor pressure can be lowered and the reactor power can be lowered. That is, steam bubbles (hereinafter referred to as voids) generated in the core 3 are separated from cooling water by a steam separator (not shown) above the core 3 and pass through the main steam control valve 14 through the main steam pipe 8. Is flowing into the steam turbine 9.

Here, for example, when the main steam control valve 14 is opened, the flow rate of steam flowing out from the reactor pressure vessel 2 increases and the pressure in the core 3 decreases, so that the proportion of voids increases. This increase in voids reduces the frequency of nuclear fission and reduces reactor power. Therefore, heat generation from the fuel is reduced and the increase of voids is suppressed, so that the output is low and stable.

On the other hand, in the core 3, when a rapid change in neutron flux is detected by a neutron flux detector which is an output detector (not shown), all the control rods 6 including the selective control rods 6a are urgently placed in the core 3. To shut down the reactor (scrum). For example, when the neutron flux rises during rated operation and exceeds, for example, 120% of the scrum set value, the reactor is shut down by this scrum operation.

As described above, in a nuclear power plant, measures for always safely shutting off the reactor output are taken, but the reactor shutdown by this scrum is not performed very often from the viewpoint of the operating rate of the nuclear power plant. Better In order to do so, it is necessary to ensure a stable power supply by not stopping the operation of the reactor or reducing the output only in the event that does not affect the safety of reactor equipment. An example of an event that does not occur is a medium-scale earthquake.

[0019]

Conventionally, in a nuclear power plant, in the case of a large earthquake, there is a scrum interlock which detects and activates the large earthquake acceleration, which automatically shuts down the reactor. I am letting you. However, in the case of an earthquake that is not so large, the equipment and piping system inside the reactor building are shaken, and the number of voids in the reactor core 3 is reduced, or the neutron flux and output are temporarily changed due to changes in the reactor internal conditions. A rise may occur.

As shown in the reactor characteristic diagram of FIG. 10, when a medium-scale earthquake occurs, the seismic wave 26 due to the earthquake, as shown in FIG. 10 (a), is generally a small initial microtremor wave 26a followed by the main vibration wave 26b. Is transmitted, and the main vibration wave 26b ends in a short time, and after this, the main vibration wave 26b is as large as the main vibration wave 26b.
26 rarely arrives repeatedly.

Therefore, as shown in FIG. 10 (b), in the reactor vibrated by the seismic wave 26, the voids in the core 3 disappear, or the state of the reactor temporarily changes, and accordingly the neutrons are changed. The bundle 27 changes as shown by the solid line and the fuel surface heat flux 28 changes as shown by the dotted line. The alternate long and short dash line in the figure indicates the scrum setting value 29 (120%).

At this time, the neutron flux 27 may increase up to 120% which is the scrum setting value 29 of the reactor depending on the earthquake, but this neutron flux 27 causes the voids in the reactor due to the power increase in the core 3. The increase is decreased in a short time, and such a behavior is finished in about several seconds. Therefore, the increase of the surface heat flux 28 is as small as several%, and the soundness of the fuel rod 6 is not hindered.

However, in the conventional boiling water reactor, in the scram interlock due to the large seismic acceleration set as described above, the neutron flux 27 is set to the scrum set value 29 even in the case of a small or medium-scale earthquake. If it exceeds (120%), there is a problem that it immediately scrums.

The reactor automatically shuts down safely due to this scrum, but as described above, the phenomenon in which the neutron flux 27 exceeds the scrum value 29 is a transient transient phenomenon that returns after a few seconds, There is no safety problem because it is not a failure of the reactor equipment. However, in response to such an event, the reactor is unnecessarily and frequently shut down, or the output is reduced in order to avoid this, the operating rate is reduced as a nuclear power plant, and the stability of electric power is reduced. There was the problem of damaging supply.

The object of the present invention is to detect the microvibration of the reactor due to the initial microtremor wave of an earthquake and control the control rod or core flow rate to suppress the temporary increase of the neutron flux. It is an object of the present invention to provide a reactor power control device that avoids unnecessary scrum and suppresses reactor shutdown or power reduction in the case of a small or medium-scale earthquake that does not require shutdown.

[0026]

In order to achieve the above object, a reactor power control apparatus according to a first aspect of the present invention controls a control rod drive mechanism for controlling a control rod position in a reactor and a core flow rate. In a reactor power control device equipped with a core flow control device, an earthquake detector that detects the occurrence and extinction of an earthquake, and a control rod operation signal and core flow control based on the earthquake detection signal from this earthquake detector and the core and plant information. A reactor control device including a reactor control device that outputs a signal is provided.

A reactor power control apparatus according to a second aspect of the present invention is characterized in that the control rod operation signal output from the reactor control apparatus in the reactor control apparatus causes the control rods to be shallowly inserted into the core. A reactor power control apparatus according to a third aspect of the present invention is characterized in that a core flow rate control signal output by the reactor control apparatus in the reactor control apparatus holds the reactor output or the generator output constant.

According to a fourth aspect of the present invention, there is provided a reactor power control device, wherein the reactor control device in the reactor control device pulls out a control rod deeply inserted into a core, and a reactor power output or a generator. It is characterized in that a core flow rate control signal for keeping the output constant is output.

According to a fifth aspect of the present invention, there is provided a reactor power control device, wherein the reactor control device in the reactor control device inserts a control rod operation signal for inserting a control rod near the outermost periphery of the core.
It is characterized in that a core flow rate control signal for keeping the reactor output or the generator output constant is output.

[0030]

According to the invention described in claim 1, the reactor vibrates due to an earthquake, but the earthquake detector detects the slight vibration of the reactor due to the initial microtremor wave which is a precursory phenomenon of a full-scale earthquake transmitted to the reactor. , Output the earthquake occurrence signal to the reactor control device. Upon receipt of this earthquake occurrence signal, the reactor control device changes the position of the control rods via the control rod drive mechanism to make the axial power distribution in the core a top peak type.

As a result, voids in the core are crushed due to the main vibration later, fluctuations in the core flow rate occur, and the relative position and sensitivity to the neutron measuring instrument change, which causes a temporary increase in the neutron flux. Even if it is possible to reduce the amount of voids that are the main cause, especially in the lower core and subcooled boiling region of large neutron flux and power importance, because the boiling length is shortened while moving the void distribution to the upper part in advance, The impact of neutron flux increase due to the main vibration is small.

Furthermore, since the reactor control unit adjusts the core flow rate so as to maintain or slightly lower the reactor power as the position moves to the control rod, the fluctuation of the reactor power is small and the scrum is avoided. .

According to a second aspect of the present invention, the reactor control device, to which the seismic signal from the seismic detector is input, outputs a shallow rod insertion signal to the control rod drive mechanism so that the control rod is shallowly inserted into the core. . As a result, the axial power distribution in the core becomes a top peak type, and the reactor power decreases, but even if fluctuations such as a temporary increase in neutron flux due to void collapse in the core due to the main vibration occur, The impact is small and scrum is avoided.

According to a third aspect of the present invention, the reactor control device to which the seismic signal from the seismic detector is input is arranged so that the reactor flow rate control device keeps the reactor output or the generator output constant. Output a control signal. As a result, even if fluctuations such as a temporary increase in neutron flux due to void collapse in the core due to the main vibration occur afterwards, scram is avoided without the reactor power exceeding the scrum setting value.

According to a fourth aspect of the present invention, the reactor control device receiving the earthquake occurrence signal from the earthquake detector causes the control rod deeply inserted into the core to be pulled out so that the axial power distribution in the core has a top peak. Make a mold. As a result, the neutron flux does not exceed the scrum set value even if fluctuations such as a temporary increase in the neutron flux due to void collapse in the core due to the main vibration are generated later.

Further, since the reactor controller outputs the control rod withdrawal signal and the core flow control signal for keeping the reactor output or the generator output constant to the reactor core flow controller, the reactor output fluctuation due to an earthquake does not occur. No, scrum is avoided.

According to a fifth aspect of the present invention, the reactor control device which receives the earthquake occurrence signal from the earthquake detector inserts a control rod near the outermost periphery of the core so that the axial power distribution in the core has a top peak. Make a mold. As a result, the neutron flux does not exceed the scrum set value even if fluctuations such as a temporary increase in the neutron flux due to void collapse in the core due to the main vibration are generated later.

Further, since the reactor control unit outputs the control rod withdrawal signal and the core flow rate control signal for keeping the reactor output or the generator output constant to the reactor core flow rate control unit, fluctuations in the reactor output due to an earthquake do not occur. No, scrum is avoided.

[0039]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. It should be noted that the same components as those of the above-described conventional technique are denoted by the same reference numerals and detailed description thereof will be omitted. The first embodiment is shown in FIG.
As shown in the block diagram of FIG. 1, in the core 3 installed in the reactor pressure vessel 2, a control rod 6 and a selective control rod 6a for adjusting the output of the control rod 6 and a shallow insertion control are provided together with a fuel assembly (not shown). A rod 6b (hereinafter referred to as a shallow rod) is provided so as to be connected to the control rod drive device 7. Further, the reactor pressure vessel 2 includes a recirculation pump 4 for controlling the core flow rate.
And the core flow rate control device 5 are connected.

Further, a reactor control device 30 which is a part of the reactor power control device includes an earthquake detector 31 attached to the reactor for detecting a microvibration of the reactor due to an initial microtremor which is a sign of an earthquake, In response to the seismic signal S ₁ from the seismic detector 31, the plant information signal S ₂ of the core 3 measured and calculated, and the command input S ₃ from the operator, etc., the shallow rod according to the state of the core 3 and the plant. 6b is the operation, it is constituted by a furnace control device 32 that outputs a shallow rod insertion signal S _4.

In the furnace control device 32, there is generally almost no decrease in the furnace output due to the insertion of the shallow rod 6b, so normally it is not necessary to control the flow rate for maintaining the furnace output, but if the output fluctuation is large. In this case, the flow rate adjusting signal S ₅ is output to the core flow rate control device 5 to control the core flow rate (and thus the output), whereby the core output can be maintained finely.

Next, the operation of the above configuration will be described. In the nuclear reactor at the time of an earthquake in the nuclear power plant, as shown by the vibration 33 in the vibration characteristic diagram of FIG. 2, first, the small vibration 33a caused by the initial microtremor wave 26a (shown in FIG. 10), which is a precursor of a full-scale earthquake, occurs. , And then main vibration 33b caused by main vibration 26b
b occurs. However, this main vibration 33b is the main vibration wave of the earthquake.
It disappears with the end of 26b.

When this earthquake was transmitted, the reactor control device
An earthquake detector 31 associated with the reactor at 30 detects the micro vibration 33a and outputs an earthquake occurrence signal S ₁ to the reactor controller 32. As a result, the furnace control device 32 immediately issues the shallow rod insertion signal S ₄ to the control rod drive mechanism 7, and shallowly inserts the shallow rod 6b into the core 3.

The behavior of the coolant in the core 3 at the normal time is shown in the fuel peripheral schematic diagram of FIG. 3, and the axial relative power distribution in the core 3 at this time is shown in FIG. It is shown by a dotted line 34 in the comparative characteristic diagram. The void fraction distribution is shown by the dotted line 37 in the void fraction comparison characteristic diagram of FIG.

However, here, the shallow rod 6b
Is inserted, the relative power distribution in the core 3 becomes as shown in FIG.
In the boiling region of the core 3 shown in FIG. 3, the subcool boiling region 36 near the bottom of the reactor moves axially upward and shrinks. further,
The void fraction distribution changes as shown by the solid line 38 in FIG.
The contribution of the void fraction in each region is reduced in advance before the main vibration 33b that occurs later.

Therefore, since such a state is set in advance, even if the main vibration 33b occurs after that, the contribution of the void fraction of each region in the reactor is already in the solid line 38.
As shown in, the positive reactivity input due to the influence of the reactor vibration due to the earthquake is small. The main vibration 33b disappears with the end of the earthquake.

As a result, an increase in the neutron flux distribution in the core 3 at the time of a small or medium-scale earthquake is easily suppressed. Therefore, as shown by the solid line in the neutron flux characteristic diagram of FIG. The increase is not so large that it exceeds the dash-dotted line scrum setting value 29 as shown by the conventional dotted line 27, and therefore, the reactor shutdown due to unnecessary scrum caused by a small or medium-scale earthquake is easy. It can be avoided.

Further, the reactor control device 32 outputs a flow rate adjusting signal S ₅ to the core flow rate control device 5 to control the core flow rate so that the output can be precisely maintained, so that the reactor holds the output. Since the operation is continued with only a slight decrease or a slight decrease, stable power supply is possible.

Of course, if the earthquake is large-scale and the main vibration 33b after the initial micro-vibration 33a is extremely large and the neutron flux 39 resulting from this exceeds the scrum set value 29, The reactor is safely stopped by a separate scrum operation. Although the above has described the action at the time of the occurrence of an earthquake, including the second embodiment and the third embodiment to be described later, at the time of the end of the earthquake, by performing the action opposite to that at the time of the occurrence, It goes without saying that the state before the earthquake can be easily restored.

In the second embodiment, as shown in the block diagram of FIG. 7, in the core 3 in the reactor pressure vessel 2, a fuel rod (not shown) is used together with the control rod 6 and a part thereof for adjusting the output. The selection control rod 6a is connected to the control rod driving device 7. Further, to the reactor pressure vessel 2, a recirculation pump 4 for controlling the core flow rate and a core flow rate control device 5 are connected.

The reactor control device 40, which is a part of the reactor power control device, is composed of an earthquake detector 31 and a reactor control device 41. In this reactor control device 41, the earthquake detector 31 is the initial earthquake sign. the earthquake generation signals S ₁ to emit and detect, receiving a command input S ₃ from such measurements and the calculated plant information signal S ₂ and the operator of the core 3.

As a result, the reactor control system 40 controls the control rod drive mechanism 7 according to the states of the reactor core 3 and the plant.
A flow rate for holding or slightly lowering the reactor output by outputting an operation signal S ₆ for pulling out the selection control rod 6a inserted in the core 3 and adjusting the core flow rate to the core flow rate control device 5. It is configured to output the adjustment signal S ₅ .

Next, the operation of the above configuration will be described. When the initial micro-vibration 33a, which is a precursor of an earthquake, occurs in the nuclear reactor of the nuclear power plant, the earthquake detector 31 detects it and outputs the earthquake generation signal S ₁ to the reactor controller 41. The reactor control device 41 receives the signal S ₁ from the seismic detector 31, the measured and calculated core plant information signal S ₂ and the command input S ₃ , and outputs the extraction operation signal S ₆ according to the core plant state. Then, an appropriate one is selected from the control rods 6 inserted in the core 3, and the selected control rods 6 a are pulled out by the control rod drive mechanism 7.

At the same time, the reactor controller 41 instructs the core flow controller 5 to adjust the flow rate S ₅ of the core flow rate (and hence the output).
Is output to perform a reduction operation of the core flow rate. As a result, although the reactor output increases due to the withdrawal of the selective control rod 6a, the core flow rate decreases and the reactor output decreases so as to offset this, so that the reactor is maintained at the desired output. You can drive.

The state in the core 3 at this time is such that the axial power distribution becomes a top peak type as shown by the solid line 35 in FIG. 4, and as shown by the solid line 38 in FIG. The subcool boiling region 36 near the bottom of the furnace shown in FIG. 3 moves axially upward and shrinks, and the contribution of the void fraction in these regions decreases before the main vibration 33b that occurs later. As a result, even if the main vibration 33b occurs due to a small or medium-scale earthquake,
Since the contribution of the void fraction in these regions is already small, the positive reactivity input due to the influence of the earthquake is small.

Therefore, the increase of the neutron flux 39 as shown by the solid line in FIG. 6 does not exceed the scrum setting value 29 of the dashed line as shown by the conventional dotted line 27, and is caused by unnecessary scrum. Since the reactor shutdown can be easily avoided, stable power supply can be easily performed.

In the third embodiment, as shown in the block diagram of FIG. 8, in the core 3 in the reactor pressure vessel 2, the fuel rods (not shown) are used together with the control rod 6 and a part thereof for power adjustment. The selection control rod 6a is connected to the control rod driving device 7. Further, to the reactor pressure vessel 2, a recirculation pump 4 for controlling the core flow rate and a core flow rate control device 5 are connected.

The reactor control device 42, which is a part of the reactor power control device, is composed of an earthquake detector 31 and a reactor control device 43. In this reactor control device 43, the earthquake detector 31 gives an initial earthquake sign. It receives an earthquake occurrence signal S _{1 that} is detected and emitted, a plant information signal S ₂ of the core 3 that has been measured and calculated, and a command input S ₃ from an operator or the like.

As a result, the reactor control system 42 controls the control rod drive mechanism 7 according to the states of the reactor core 3 and the plant.
Among the control rods 6 inserted in the core 3, the pull-out operation signal S ₇ of the control rod 6c near the outermost periphery of the core 3 which is arranged in the vicinity of the outermost periphery of the core 3 is output and the core flow rate control device 5 A core flow rate adjustment operation is performed to output a flow rate adjustment signal S ₅ for maintaining or slightly reducing the reactor output.

Next, the operation of the above configuration will be described. When the initial microvibration 33a, which is a precursor of an earthquake, occurs in the nuclear reactor of the nuclear power plant, the seismic detector 31 detects it and issues an earthquake generation signal S ₁ to the reactor control device 43.

The reactor control unit 43 receives the earthquake occurrence signal S ₁ from the earthquake detector 31, the measured and calculated core plant information signal S ₂ and the command input S ₃ , and determines the outermost circumference according to the core plant state. A control rod drive mechanism is output by outputting a control rod insertion operation signal S ₇ and selecting an appropriate control rod 6c for the outermost periphery of the control rods 6 such as the outermost periphery of the core 3 or within the third layer. The insertion operation is performed through 7.

Further, the reactor controller 43 is the core flow controller 5
A core flow rate adjustment operation is carried out with respect to, and a flow rate adjustment signal S ₅ for holding or slightly decreasing the reactor output is output. As a result, the reactor output tends to decrease due to the insertion of the control rod 6c in the vicinity of the outermost periphery, but the output tends to increase due to the increase in the core flow rate so as to offset this, so operation is performed to maintain the desired output. be able to.

The control rod 6c near the outermost circumference is inserted as follows.
It can be easily operated and the power can be finely adjusted without causing a local large change in the core characteristics. Moreover, the axial power distribution in the furnace can be averaged into a top peak type. As a result, the state in the core 3 has the same effects and advantages as those of the first and second embodiments, and avoids an unnecessary scrum stop during a small-to-medium-scale earthquake and a stable power supply. can do.

[0064]

As described above, according to the present invention, in a nuclear power plant, when a small or medium-scale earthquake that does not substantially require the reactor to be stopped by a scrum is stopped, the reactor is frequently shut down or drastically increased due to an increase in neutron flux. Since a decrease in output can be safely avoided and a stable reactor output holding operation can be performed, there is a great effect in improving the reliability of the operation of the nuclear power plant and the stabilization of the power supply.

[Brief description of drawings]

FIG. 1 is a block configuration diagram of a reactor control device according to a first embodiment of the present invention.

[Fig.2] Reactor vibration characteristics during an earthquake.

FIG. 3 is a schematic diagram of a fuel periphery in a core.

FIG. 4 is a relative power distribution map in the core axial direction of one embodiment according to the present invention.

FIG. 5 is an axial void ratio distribution diagram in the core of one embodiment according to the present invention.

FIG. 6 is a neutron flux characteristic diagram during an earthquake.

FIG. 7 is a block configuration diagram of a reactor control system according to a second embodiment of the present invention.

FIG. 8 is a block configuration diagram of a reactor control system according to a third embodiment of the present invention.

FIG. 9 is a schematic configuration diagram of a nuclear power plant.

FIG. 10 is a reactor characteristic diagram at the time of an earthquake, (a) shows an earthquake waveform, and (b) shows a neutron flux and a fuel surface heat flux.

[Explanation of symbols]

1 ... Reactor containment vessel, 2 ... Reactor pressure vessel, 3 ... Reactor core,
4 ... Recirculation pump, 5 ... Core flow rate control device, 6 ... Control rod, 6a ... Selection control rod, 6b ... Shallow rod, 6c ...
Control rods near the outermost periphery, 7 ... control rod drive mechanism, 8 ... main steam pipe, 9 ... steam turbine, 10 ... jet pump, 11, 12 ...
Main steam isolation valve, 13 ... Main steam stop valve, 14 ... Main steam control valve,
15 ... Generator, 16 ... Condenser, 17 ... Condensate pump, 18 ... Water heater, 19 ... Water pump, 20 Turbine bypass pipe, 21 ... Turbine bypass valve, 22 ... Main steam relief valve, 23 ... Main steam Escape pipe, 24 ... Pressure suppression chamber, 25 ... Pool water, 26 ... Seismic wave, 26a ... Initial microtremor wave, 26b ... Main vibration wave, 27 ... Neutron flux, 28 ... Fuel surface heat flux, 29 ... Scrum set value, 30 ,Four
0, 42 ... Reactor control device, 31 ... Earthquake detector, 32, 41, 43
… Reactor control device, 33… Reactor vibration, 33a… Initial micro vibration, 33
b ... main vibration, 34 ... normal power distribution curve, 35 ... power distribution curve according to the present invention, 36 ... subcool boiling, 37 ... normal void fraction curve, 38 ... void fraction curve according to the present invention, 39 ... present invention Neutron flux, S ₁ ... Earthquake occurrence signal, S ₂ ... Plant information signal, S ₃ ... Command input, S ₄ ... Shallow rod insertion signal, S ₅ ... Flow rate adjustment signal, S ₆ , S ₇ ... Extraction operation signal.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Akihiko Hoshide 8 Shinsita-cho, Isogo-ku, Yokohama-shi, Kanagawa Stock Company Toshiba Yokohama Office

Claims (5)

[Claims] 1. A reactor output control device equipped with a control rod drive mechanism for controlling the position of control rods in a nuclear reactor and a core flow rate control device for controlling core flow rate, and an earthquake detector for detecting the occurrence and disappearance of an earthquake. And a reactor control device comprising a seismic detection signal from this seismic detector and a reactor control device that outputs a control rod operation signal and a core flow rate control signal based on core and plant information Control device. 2. The reactor power control device according to claim 1, wherein the control rod operation signal output from the reactor control device in the reactor control device causes the control rod to be inserted shallowly into the core. 3. The reactor output control device according to claim 2, wherein the core flow rate control signal output by the reactor control device in the reactor control device holds the reactor output or the generator output constant. 4. The reactor control device in the reactor control device outputs a control rod operation signal for pulling out a control rod deeply inserted into the core and a core flow rate control signal for holding the reactor output or the generator output constant. The reactor power control system according to claim 1, wherein 5. The reactor control device in the reactor control device outputs a control rod operation signal for inserting a control rod near the outermost periphery of the core and a core flow rate control signal for holding the reactor output or the generator output constant. The reactor power control device according to claim 1, wherein