JPS6232440B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an emergency core cooling equipment control device for a nuclear reactor that controls emergency equipment such as an emergency core cooling pump of a nuclear reactor.

[Technical background of the invention and its problems]

Generally, in boiling water reactors, etc., a drop in the water level in the reactor pressure vessel and a rise in pressure in the reactor containment vessel are detected, and emergency equipment, such as an emergency core cooling system, is activated automatically in the event of an emergency such as a loss of coolant accident. is configured to start automatically. Further, in order to improve the operability of such an emergency core cooling facility, the emergency core cooling facility is configured to be able to be started and stopped manually. Conventionally, a control device for such an emergency core cooling facility has been constructed as shown in FIG. That is, when signals are output from the water level detector B, which detects a decrease in the water level in the reactor pressure vessel A, and the pressure detector D, which detects a pressure increase in the reactor containment vessel C, via the converters T and U, About 1 second after contacts E and F of a relay are closed, relay G is energized, and timer H is activated, about 1 second after contact I of timer H is opened and relay G is energized. It is energized for only a second, and during this time, the contact J of this relay G is closed, and a closing command is sent from the closing command circuit K to the circuit breaker L, and the pump M of the emergency core cooling system is activated to shut down the inside of the reactor pressure vessel A. is configured to supply cooling water to the The input command circuit K is provided with a manual start switch N in parallel with the contact J, so that the pump M can be started manually. Further, O is a cutoff command circuit, which detects a state in which the emergency core cooling system should be protected and closes the contact Q of the relay P.
It is configured to send a shutdown command to the circuit breaker L described above to stop the pump M and the like. This cutoff command circuit O is provided with a manual stop switch R in parallel with the contact Q of the relay P.
is configured so that it can be stopped. Note that the circuit breaker L is closed by a closing command and opened by a shutoff command. By the way, if a loss of coolant accident occurs and the water level in the reactor pressure vessel A decreases, and the pressure in the reactor containment vessel C rises and the emergency core cooling system is activated, normally, the water level in the reactor pressure vessel A decreases. Although the water level S within the reactor containment vessel C will soon recover, the pressure within the reactor containment vessel C will not decrease for a long time. Therefore, if the water level S in the reactor pressure vessel A recovers and the emergency core cooling system is manually shut down, the pressure in the reactor containment vessel C will not decrease, so the contact F will remain closed and the timer H will be activated. continues to be energized and its contact I remains open, so in the unlikely event that a loss of coolant accident continues, the water level S in the reactor pressure vessel A will drop again and the water level detector B will be activated. Operated and contact E
Even if the switch is closed, the contact I remains open, so a command to turn on the pump M will not be generated unless the manual start switch N is operated. Because the operations were complicated, there was a possibility of erroneous operation.

[Purpose of the invention]

The purpose of the present invention is to provide a highly reliable emergency core for a nuclear reactor, which allows emergency equipment such as emergency core cooling pumps to be started and stopped manually, providing convenient operability, and eliminating the possibility of erroneous operation in an emergency. An object of the present invention is to provide a cooling equipment control device.

[Summary of the invention]

The present invention includes a water level detector that detects when the water level of cooling water in the reactor pressure vessel has fallen below a predetermined value and outputs a low water level signal, and a water level detector that outputs a low water level signal when the water level of the cooling water in the reactor pressure vessel has decreased to a predetermined value or higher. a pressure detector that outputs a high pressure signal upon detecting that the water level is low; Manually start the emergency core cooling equipment,
In an emergency core cooling equipment control device for a nuclear reactor that has a manual start switch and a manual stop switch for shutting down, when the manual stop switch is operated when the high pressure signal is output, the output of the high pressure signal is changed to the high pressure signal. Emergency core cooling equipment control for a nuclear reactor that automatically starts the emergency core cooling equipment of a nuclear reactor only by a low water level signal by providing a circuit that is disconnected from the activation signal generation circuit of the emergency core cooling equipment of a nuclear reactor. In the event of a loss of coolant accident, the emergency core cooling equipment will automatically operate, and once the reactor water level has recovered, the above equipment will be shut down using a manual shutdown switch, and then the nuclear reactor will be restarted. When the reactor water level drops, for example, even if a high pressure signal in the reactor containment vessel continues, the emergency core cooling equipment is automatically activated again to achieve the above objective.

[Embodiments of the invention]

The present invention will be described below with reference to an embodiment shown in FIG.

A reactor pressure vessel 1 is housed in a reactor containment vessel 2. Emergency core cooling equipment, such as a pump 3 for injecting cooling water, is connected to the reactor pressure vessel 1 via piping, and when the water level S in the reactor pressure vessel 1 drops, cooling water is supplied from a water source 30. I'm starting to do that. The pump 3 is provided with a circuit breaker 4 for starting and stopping the pump.

A pressure detector 5 is provided inside the reactor containment vessel 2 and outputs a high pressure signal when the internal pressure rises above a predetermined pressure. There is. The reactor pressure vessel 1 also has a water level detector 6 that outputs a low water level signal when the reactor water level S drops below a predetermined water level.
is provided and introduced into the control circuit 7 via the converter 6a.

The circuit breaker 4 is closed and shut off by signals from the closing command circuit 15 and the shutting command circuit 17, and starts and stops the drive motor (not shown) of the pump 3. The main part of the turn-on command circuit 15 is composed of a parallel circuit of a contact 14 that is closed by a signal from the control circuit 7 and a manual start switch 16, and the main part of the cut-off command circuit 17 is composed of a parallel circuit of a contact 14 that is closed by a signal from the control circuit 7 and a manual start switch 16. It is constituted by a parallel circuit of a closing contact 19 of an equipment protection relay 18 energized by the operation of a protection detection mechanism (not shown) and a manual stop switch 20.

The details of the control circuit 7 include a group of contacts connected between the power supply buses X and Y, a relay, and the like. That is, a water level signal contact 9, which is closed in response to a low water level signal from the converter 6a, is placed in series with a timer 11 having a contact 13, which opens approximately 1 second after energization.
It is connected between bus lines X and Y. A series circuit of contacts 13 and relay 12 is connected in parallel with timer 11. A pressure signal contact 8, which is closed in response to a high pressure signal from the converter 5a, is connected in series with the normally closed contact 10 of the relay 22 and in parallel with the water level signal contact 9. Pressure signal contact 8 and contact 10
From the connection point, the relay 22 and its normally open contact 23
A series circuit of is connected to bus Y. A contact 21 which is closed in conjunction with the operation of the manual stop switch 20 is connected to the contact 23 in parallel.

Next, its effect will be explained.

When the manual start switch 16 is closed, a closing command is issued, the circuit breaker 4 is closed, and the pump 3 is started to supply water to the reactor pressure vessel 1 . Next, by closing the manual stop switch 20, a shutoff command is issued and the pump 3 is stopped. Further, when the equipment protection relay 18 is activated while the pump 3 is in operation, the contact 19 is closed and the pump 3 is stopped.

Here, in the unlikely event that a reactor coolant loss accident occurs and the reactor water level S decreases or the pressure inside the reactor containment vessel 2 increases, the water level detector 6
A low water level circuit and a high pressure signal are generated from the water level detector 5, which close the water level signal contact 9 and the pressure signal contact 8, respectively. Closing one or both of these contacts causes timer 11
and relay 12 is energized, thereby contact 14
is closed, the circuit breaker 4 is closed, the pump 3 is started, water is supplied from the water source 30 to the reactor pressure vessel 1, and the reactor water level S rises. Since contact 13 opens after about 1 second, relay 12 is opened and contact 1
4 will also be developed. Once the reactor water level S has recovered, when the manual stop switch 20 is closed, the pump 3 is stopped via the circuit breaker 4, and water supply is stopped. In conjunction with the operation of the manual stop switch 20, the contact 21 is closed during that time, but if the pressure inside the reactor containment vessel 2 is decreasing at this time and the pressure signal contact 8 is open, the water level Since the signal contact 9 is naturally opened due to the recovery of the reactor water level S,
There is no effect on the control circuit 7.

However, as mentioned above, generally the reactor containment vessel 2
Once a reactor coolant loss accident occurs, the pressure signal contact 8 remains closed because the pressure within the reactor does not decrease for a long period of time even after the reactor water level S has recovered. However, even in this case, the relay 22 is energized by the contact 21 that closes when the manual stop switch 20 is closed, and is self-held by the closing of the contact 23, while the contact 10 is opened. Therefore, the energization of timer 11 is released and contact 1
3 is closed. Therefore, after this, for example, if the reactor water level S decreases again due to continued coolant leakage, the water level signal contact 9 will be activated regardless of whether there is a high pressure signal from the pressure detector 5. Following the same process as described above, a command to turn on the pump 3 is immediately issued automatically, water is supplied into the reactor pressure vessel 1, and the reactor water level S can be restored.

In this embodiment, the control circuit 7 and the like are constructed of contacts and relays, but semiconductor switches or the like may be used instead of these.

Further, the contact 21 may be an independent switch that does not operate in conjunction with the manual stop switch 20.

〔Effect of the invention〕

As is clear from the points detailed above, according to the present invention, even if the reactor water level that has fallen due to a loss of reactor coolant accident, etc. has recovered and then falls again, the water level inside the reactor containment vessel remains It is possible to automatically resupply water regardless of whether the pressure is high or low, and has the effect of providing highly reliable emergency core cooling equipment for a nuclear reactor that prevents the possibility of erroneous operation.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing a conventional emergency core cooling equipment control system for a nuclear reactor, and FIG. 2 is a circuit diagram showing an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Reactor pressure vessel, 2... Reactor containment vessel, 3... Pump, 4... Circuit breaker, 5... Pressure detector, 6... Water level detector, 7... Control circuit, 8...
...Pressure signal contact, 9...Water level signal contact, 10...
Contact of relay 22, 11...Timer, 12, 22
...Relay, 20...Manual stop switch, 21...
…contact.

Claims (1)

[Claims] 1. A water level detector that detects when the water level of cooling water in the reactor pressure vessel has fallen below a predetermined value and outputs a low water level signal, and a water level detector that outputs a low water level signal when the water level of the cooling water in the reactor pressure vessel has fallen below a predetermined value, and a a pressure detector that detects and outputs a high pressure signal; a circuit that generates a start signal for emergency core cooling equipment of a nuclear reactor in response to signal input of at least one of the low water level signal and the high pressure signal; In an emergency core cooling equipment control device for a nuclear reactor having a manual start switch and a manual stop switch for manually starting and stopping the emergency core cooling equipment, the manual stop switch is used to perform a shutdown operation when the high pressure signal is output. A nuclear reactor characterized in that a circuit is provided to separate a high pressure signal from a start signal generation circuit of an emergency core cooling facility of a nuclear reactor when a high pressure signal occurs, and the emergency core cooling facility of a nuclear reactor is started only by the low water level signal. emergency core cooling equipment control system.