JPH063479A - Control equipment of reactor power - Google Patents

Abstract

PURPOSE:To obtain control equipment of a reactor power which ensures the water level of a reactor and controls the reactor power automatically and safely, by providing a recirculation from an injection piping of a high pressure injection system to a pressure control chamber pool and a flow control device and by injecting a high pressure injection flow corresponding to the water level of the reactor set beforehand, from the high pressure injection system, when scram fail transient phenomena take place. CONSTITUTION:An injection piping 15 of a high pressure injection system connected to a feed water piping 3 and a high pressure injection recirculation system branching from this injection piping 15 of the high pressure injection system, communicating with a pressure control chamber room 7 and being equipped with a flow regulating means 20 are provided. By controlling the flow regulating means 20 by a power control device 23 comprising a scram fail transient phenomenon determining part, a high pressure injection system needed injection flow calculating part and a control signal calculating part, a flow rate of feed water to a reactor at the time when scram fail transient phenomena of the reactor take place is controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to control of reactor power during a non-scram transient event in a boiling water reactor, and in particular, automatic injection of water from a high-pressure injection system into the reactor during a non-scram transient event. The present invention relates to a reactor power control device that controls the water level and power of a reactor.

[0002]

2. Description of the Related Art Generally, in a boiling water reactor, FIG.
As shown in the configuration diagram of the reactor high-pressure water injection system, a reactor pressure vessel 2 accommodating a reactor is installed inside the reactor containment vessel 1, and the reactor pressure vessel 2 is stored from the outside. A water supply pipe 3 through which a water supply pump (not shown) for guiding the water supply through the container 1 is inserted, and a main steam pipe 4 for drawing out the high-temperature high-pressure steam generated inside is connected to the main steam pipe 4. A main steam relief safety valve 5 and a main steam isolation valve 6 are provided.

Below the reactor containment vessel 1 is communicated with the reactor containment vessel 1, and a pressure suppression chamber in which pool water is stored for condensing steam to prevent pressure rise in the reactor containment vessel 1. Pool 7 is installed. In this pressure suppression chamber pool 7, the main steam relief safety valve 5 to the exhaust pipe 8 are provided.
Are connected.

Further, the pressure suppression chamber pool 7 is a pool-side high-pressure water injection system suction pipe 12 and a tank-side high-pressure water injection system suction pipe with a condensate storage tank 9 and high-pressure water injection system water source switching valves 10 and 11 interposed.
Connected with 13.

Further, the pool side high pressure water injection system suction pipe
A high-pressure water injection system injection pipe 15 having a high-pressure water injection system pump 14 interposed is connected between the water supply pipe 12 and the water supply pipe 3, and communicates with the reactor pressure vessel 2 to form a high-pressure water injection system. .
When the supply water flow rate is lost and the reactor water level is lower than in the normal operating state, the reactor is scrammed while the reactor water level is low (set value L3).

As a result, the flow rate of steam flowing out from the reactor pressure vessel 2 through the main steam pipe 4 is suppressed, and the decrease in the reactor water level becomes slow. However, since the decay heat is generated in the nuclear reactor even when it is scrammed, steam generation of about 5% of the rated steam flow rate is usually continued. Therefore, if the supply water flow rate corresponding to this steam generation amount cannot be secured, the reactor water level further decreases due to the mismatch between the inflow amount and the outflow amount, and finally reaches the reactor water level low (L2).

When the reactor water level reaches the reactor water level at a low level (L2), the main steam isolation valve 6 is closed, and the reactor isolation cooling system (Reactor Core Isolation) which is a safety protection device is closed.
Cooling System RCIC) and high pressure emergency core cooling system (high pressure)
Emergency Core Cooling System ECCS) is automatically started to prevent the reactor water level from dropping below this level.

On the other hand, since the main steam isolation valve 6 is closed, the pressure in the reactor pressure vessel 2 rises due to the steam generated by the decay heat, and the main steam relief safety valve 5 provided in the main steam pipe 4 is closed. When the set pressure is reached, the main steam isolation valve relief safety valve 5 is opened, and a part of the generated steam is discharged to the pressure suppression chamber pool 7 through the exhaust pipe 8 of the main steam relief safety valve 5 to increase the reactor pressure. Suppressed. In this way, the reactor water level and reactor pressure are safely controlled. However, although the probability of actually occurring is considered to be extremely low, the following situation is assumed assuming that the reactor scrum fails.

When the feed water flow rate is lost from the normal operating state, the reactor water level decreases and the reactor water level low (L3) causes the reactor scrum signal to be emitted, but the insertion of all control rods fails for some reason. Suppose.

As a result, the reactor water level further decreases to reach the reactor water level at a low level (L2), and the main steam isolation valve 7 is closed. Also, since an automatic start signal for the reactor isolation cooling system and the high-pressure emergency core cooling system (not shown) is generated, water injection is started in the reactor and the reactor water level is secured, but for that reason the core flow rate is maintained. Insufficient suppression of reactor power,
The generated steam increases the heat load on the pressure suppression chamber pool 7.

This is insufficient from the viewpoint of ensuring the soundness of the reactor containment vessel 1, and therefore the following means have been conventionally considered in order to avoid such a situation. .

Unscrambling Transient (Anticipated Tran
sient Without Scram ATWS) In order to reduce the initial reactor power and suppress the amount of generated steam as much as possible, a reactor recirculation pump (not shown) is tripped during a transient event where scram cannot occur, and the reactor core flow is reduced to reduce the reactor power. Suppress.

Further, the feed water pump (not shown) is run back to lower the reactor water level to reduce the natural circulation force, to reduce the core flow rate to suppress the reactor power, and to suppress the scram impossible transient event initial reactor power. I try to keep it down.

After that, the operator controls the water injection flow rate into the reactor to keep the reactor water level low, the natural circulation flow rate suppressed, the core inlet flow rate suppressed, and the reactor output kept low. The heat load on the pressure suppression chamber pool 7 was minimized.

[0015]

In the conventional method for suppressing the reactor power during a non-scram transient event, the reactor recirculation pump trip, the feed water pump runback, the control of the water injection flow rate, and the manual operation of the operator are all involved. I rely on.

Moreover, in the case of a boiling water reactor (BWR / 4), even if the reactor water level is secured, the high pressure cooling system (High Pressure Coolant Injection System) is originally used.
HPCI) is the Lost of Coolant Accident
Since it is designed assuming LOCA), it is too large for the water injection flow rate during a non-scram transient event, so it is difficult to keep the reactor water level low unless the water injection flow rate is significantly reduced. The natural circulation force increases and the core flow rate cannot be controlled, and the reactor power cannot be maintained sufficiently low.

Therefore, since the reactor output cannot be sufficiently suppressed unless the operator maintains the water level lowering operation, the main steam relief valve 5 is opened and closed intermittently, and the amount of steam discharged to the pressure suppression chamber pool 7 increases. Then, there was a problem that it hinders the maintenance of the soundness of the containment vessel 1.

The object of the present invention is to provide a high pressure water injection recirculation system to the pressure suppression chamber pool from the high pressure water injection system injection pipe and a flow rate control device so that the high pressure water injection system is preset from the high pressure water injection system at the time of a transient event in which the scrum cannot be performed. A high-pressure injection flow rate equivalent to the reactor water level is injected to automatically secure an appropriate reactor water level, and the condensate storage tank water is guided to the pressure suppression chamber pool to safely control the reactor output and the containment vessel. An object of the present invention is to provide a reactor power control device capable of ensuring the soundness of the reactor.

[0019]

[Means for Solving the Problems] A high pressure water injection system injection pipe connected to a water supply pipe of a boiling water reactor and a flow rate adjusting means branched from this high pressure water injection system injection pipe and communicating with a pressure control chamber pool are provided. A high-pressure water injection recirculation system is provided, and the flow control means is controlled by an output control device consisting of a scram-impossible transient event determination unit, a high-pressure water injection system required injection flow rate calculation unit, and a control signal calculation unit to control the reactor's non-scram transient event. It is characterized by controlling the flow rate of water supply to the reactor at the time.

[0020]

[Operation] At the time of a transient unscrammable event of the reactor, the output control device judges the transient unscrambling event from the reactor output signal and the scrum operation request signal, and when the unscrammable transient event is set, the preset scram cannot be disabled. The injection flow rate is calculated from the target reactor water level during a transient event, and the condensate storage tank water or pressure control room pool water is injected into the reactor via the high-pressure injection system injection pipe and the water supply pipe.

The flow rate is automatically controlled by adjusting the recirculation flow rate by adjusting the opening of a flow rate adjusting valve which is a flow rate adjusting means controlled by the output control device. As a result, the reactor water level can be secured, the reactor output can be suppressed, and the condensate storage tank water with a low enthalpy is guided to the pressure suppression chamber pool through the high-pressure injection recirculation system to raise the temperature of the pressure suppression chamber pool water. The soundness of the reactor pressure vessel and the reactor containment vessel is secured by directly suppressing the above.

[0022]

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 designated by the same reference numerals and detailed description thereof will be omitted.

As shown in the schematic diagram of the reactor high-pressure water injection system in FIG. 1, a reactor pressure vessel 2 accommodating a reactor is installed inside the reactor containment vessel 1, and the reactor containment vessel is provided from the outside. A water supply pipe 3 is connected to which a water supply pump (not shown) that guides the water supply through 1 is inserted.

Further, a main steam pipe 4 for drawing out the high-temperature high-pressure steam generated inside the reactor pressure vessel 2 to the outside is connected, and a main steam release safety valve 5 and a main steam isolation valve 6 are connected to the main steam pipe 4. It is provided.

The lower part of the reactor containment vessel 1 is communicated with the reactor containment vessel 1, and the pressure at which pool water is stored for condensing steam to prevent pressure rise in the reactor containment vessel 1 and the like. The suppression room pool 7 is installed. An exhaust pipe 8 from the main steam relief safety valve 5 is connected to the pressure suppression chamber pool 7.

The pressure suppression chamber pool 7 is a condensate storage tank 9
And the high pressure water injection system suction pipe 12 on the pool side and the high pressure water injection system suction pipe on the tank side through the high pressure water injection system water source switching valves 10 and 11.
Connected with 13.

A high-pressure water injection system 15 is connected between the pool-side high-pressure water injection system suction pipe 12 and the water supply pipe 3 to connect a high-pressure water injection system injection pipe 15 to form a high-pressure water injection system. A flow rate adjusting valve 20 which is a flow rate adjusting means which communicates with the reactor pressure vessel 2 and further branches off from the high pressure water injection system injection pipe 15 to form a high pressure water injection recirculation system in the pressure suppression chamber pool 7. The inserted recirculation pipe 21 is in communication. A valve opening control unit 22 is connected to the flow rate adjusting valve 20, and an output control device 23 that issues a valve opening signal is connected to the valve opening control unit 22.

Further, at the time of the transient event where the scrum cannot be performed, since the rise of the pool water temperature of the pressure suppression chamber pool 7 is suppressed,
In order to lower the reactor water level for the purpose of reducing the reactor output, a feed pump (not shown) is tripped. However, in order to secure core flooding at this time, high pressure water injection system is used to inject water into the reactor.

In this high-pressure water injection system, the high-pressure water injection system pump 14 is operated to inject water, but the condensate of the condensate storage tank 9 having a small enthalpy is usually used as the water source, and the tank-side high-pressure water injection system suction pipe 13, It is injected into the reactor core in the reactor pressure vessel 2 via the high-pressure water injection system injection pipe 15 and the water supply pipe 3.

However, when the water level in the pressure suppression chamber pool 7 rises or the water level in the condensate storage tank 9 drops, the high pressure water injection system water source switching valve 10 is opened and the high pressure water injection system water source switching valve 11 is opened. By closing the water source, the pressure suppression chamber pool 7
Is switched to.

The block diagram of FIG. 2 shows the configuration and function of an output control device 23 that issues a valve opening signal of the flow rate adjusting valve 20 to the valve opening control part 22. This output control device 23 determines a scram-incapable transient event. It comprises a part 24, a high-pressure water injection system required flow rate calculation part 25, and a control valve opening calculation part 26 which is a control signal calculation part. The non-scrum transient event determination unit 24 inputs the reactor output signal S1 and the scram operation request signal S2 and determines that a non-scram transient event (ATWS) has occurred.

Further, the high-pressure water injection system required flow rate calculation unit 25 includes a scram impossible transient event signal S3 from the scram impossible transient event determination unit 24, a reactor isolation cooling system flow signal S4, and a predetermined scram impossible transient event. The time target reactor water level signal S5 is input to calculate the high pressure water injection system required flow rate at the time of a transient unscrambling event to calculate the high pressure water injection system required injection flow rate signal S6, which is output to the valve opening degree calculation unit 26.

In the method of calculating the required injection flow rate of the high-pressure water injection system performed here, the high-pressure water injection system required flow rate calculation unit 25 has a built-in preliminarily obtained reactor water level vs. reactor output (generated steam flow rate). Reactor output (flow rate of generated steam) by inputting the target reactor water level during a non-scram transient event
Further, the required flow rate of the high-pressure water injection system is calculated by subtracting the flow rate input to the reactor from a reactor isolation cooling system (not shown) from the generated steam flow rate obtained here.

The valve opening calculation unit 26 receives the high pressure water injection system required injection flow rate signal S6 and injects the required flow rate into the reactor.
The valve opening signal S7 of the flow rate adjusting valve 20 provided in the recirculation pipe 21 that controls the flow rate distributed from the high pressure water injection system water injection pipe 15 to the pressure suppression chamber pool 7 is output to the valve opening control unit 22. In this way, the flow rate of water injection into the reactor can be automatically controlled by the high-pressure water injection system at the time of a transient event that is impossible to scrum, and the reactor water level and reactor power can be automatically controlled.

When the flow rate adjusting means is another flow rate adjusting device other than the flow rate adjusting valve 20, the control signal calculating section, which is the valve opening calculating section 26, is a generator of a control signal for the flow rate adjusting apparatus. By doing so, an effect similar to that of the above-described embodiment can be obtained. Next, the operation of the above configuration will be described.

If the total feedwater flow rate is lost for some reason during the rated power operation of the reactor, the reactor water level will drop,
When the reactor water level is low (L3), the scrum request signal S2 is issued. In this state, assuming that the event that all the control rods have failed is further overlapped, at this time, in the scram impossible transient event determination unit 24 of the power control device 23, for example, the core decay heat obtained from the average power monitor signal. Reactor output signal S1 when the reactor output is 3% or more
Then, the reactor scram demand signal S2 of low reactor water level is input, it is determined that the transient event is not scram, and the transient event signal S3 of non-scram is output.

In response to this, it is assumed that the trips of the recirculation pump and the feed water pump (not shown) are operating in accordance with the operation procedure at the time of the non-scram transient event which is set for each plant.

In response to the non-scrum transient event signal S3 at the time of non-scrum transient event, the high pressure water injection system required water injection flow rate calculation unit 25 causes the reactor isolation cooling system flow signal S4 and the scram non-transient event initial target water level signal S5 ( For example, the reactor water level L1 + 1m) is input, and the high-pressure water injection system required injection flow rate signal S6 is output.

The valve opening calculation unit 26 receives the high pressure water injection system required injection flow rate signal S6, calculates the flow rate to be recirculated to the pressure suppression chamber pool 7, calculates the valve opening degree of the flow rate adjusting valve 20, and opens the valve. The degree signal S7 is output to the valve opening control unit 22. Valve opening controller 22
Then, in response to this valve opening signal S7, the valve opening of the flow rate adjusting valve 20 is controlled.

As a result, the high-pressure water injection system pump 14 injects a predetermined required flow rate into the reactor through the water supply pipe 3 using the condensate storage tank 9 as a water source. On the other hand, through the recirculation pipe 21 branched from the high-pressure water injection system injection pipe 15, the flow rate adjustment valve
The recirculation flow rate controlled by 20 is discharged to the pressure suppression chamber pool 7.

With the above arrangement, the cooling water can be injected into the reactor so as to reach the predetermined reactor water level, and the condensate storage tank water with a small enthalpy is introduced into the pressure suppression chamber pool 7 at a constant rate. Therefore, it contributes to the direct reduction of the heat load in the pressure suppression chamber pool 7.

Therefore, even at the time of the non-scrum transient event in which the total feed water flow rate loss and all control rod insertion failures in the reactor overlap, the reactor water level and reactor power are automatically controlled by modifying the existing reactor equipment, and It is possible to sufficiently secure the soundness of the reactor pressure vessel and the containment vessel. In addition, there are the following as an embodiment item according to the present invention. (1) A reactor output control device characterized in that the reactor output signal input to the output control device is a signal from an average output monitor.

(2) The injection flow rate into the nuclear reactor by the high pressure water injection system is controlled by adjusting the flow rate of the high pressure water injection recirculation system branched from the high pressure water injection system injection pipe with a flow rate adjusting valve. Reactor power control device. (3) The reactor power output control device characterized in that the high-pressure water injection recirculation system is led to the pressure control room pool.

[0044]

As described above, according to the present invention, the reactor water level and the reactor power are automatically controlled in the event of a non-scram transient, and the reactor power is appropriately suppressed to ensure the soundness of the reactor pressure vessel and the containment vessel. You can secure the sex. In addition, by injecting a part of the condensate storage tank water into the pressure control room pool, it contributes to the direct reduction of the heat load of the pressure suppression room pool, which has the effect of improving safety and reliability of the nuclear power plant. In addition, the operation of maintaining the lowering of the water level required by the operator is eliminated, and the pool temperature of the pressure suppression chamber can be safely controlled, so that the burden on the operator can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a reactor high pressure water injection system and the like according to an embodiment of the present invention.

FIG. 2 is a block configuration diagram of an output control device according to an embodiment of the present invention.

FIG. 3 is a schematic configuration diagram of a conventional reactor power control device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Reactor containment vessel, 2 ... Reactor pressure vessel, 3 ... Water supply piping, 4 ... Main steam pipe, 5 ... Main steam release safety valve, 6 ... Main steam isolation valve, 7 ... Pressure suppression chamber pool, 8 ... Exhaust pipe , 9 ... Condensate storage tank, 10, 11 ... High pressure water injection system water source switching valve, 12 ... Pool side high pressure water injection system suction pipe, 13 ... Tank side high pressure water injection system suction pipe, 14 ... High pressure water injection pump, 15 ... High pressure injection Water system injection pipe, 20 ... Flow control valve, 21 ... Recirculation pipe, 22 ... Valve opening control unit, 23 ... Output control device, 24 ... Scrum impossible transient event determination unit, 25 ... High pressure water injection system necessary water injection flow rate calculation unit, 26 ... Valve opening calculation unit, S1 ... Reactor output signal, S2 ... Scrum operation request signal, S3 ... Scrum impossible transient event signal, S4 ... Reactor isolation cooling system flow rate signal, S5 ... Scrum impossible transient event target atom Reactor water level signal, S6 ... Required injection flow rate signal for high pressure water injection system, S7 ... Valve opening signal.

Claims (1)

[Claims] 1. A high-pressure water recirculation system comprising a high-pressure water injection system injection pipe connected to a water supply pipe of a boiling water reactor and flow rate adjusting means branched from the high-pressure water injection system injection pipe to communicate with a pressure control chamber pool. In addition to the system, the flow control means is controlled by an output control device including a scram impossible transient event determination section, a high-pressure water injection system required injection flow rate calculation section and a control signal calculation section to control the reactor during a scrum impossible transient event. A reactor output control device characterized by controlling the flow rate of water supplied to the reactor.