JPH11160481A - Emergency auxiliary cooling facility of nuclear power plant - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten a periodic inspection and improve reliability, by performing maintenance inspection of a seawater pump during a normal operation. SOLUTION: An emergency cooling facility comprises a first system directly connecting a first seawater pump 10a, discharge tubing 14a, seawater supply tubing 11a, a first heat exchanger 4a and a seawater discharge tubing 12a, and a second system directly connecting a second seawater pump 10b, discharge tubing 14b, a discharge valve 15b, seawater supply tubing 11b, a second heat exchanger 4b and seawater discharge tubing 12b. The seawater supply tubing 11a of the first system and the seawater supply tubing 11b of the second system are connected by a communicating tubing 16, and a first gate valve 13a and a second gate valve 13b are directly connected to the communicating tubing 16. A third discharge tubing 14c is connected to a part branched from between the first gate valve 13a and the second gate valve 13b, and a third seawater pump 10c and a third discharge valve 15c are directly connected to third discharge tubing 14c.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a method for converting the heat generated by a residual heat removal equipment installed in a nuclear power plant, other emergency equipment and common equipment necessary for normal operation of the power plant into a final heat. The present invention relates to an emergency auxiliary cooling system for a nuclear power plant provided to escape to a sea, a river, a lake, the atmosphere, or the like, which is an escape site.

[0002]

2. Description of the Related Art An emergency auxiliary cooling system for a nuclear power plant includes:
It consists of a freshwater loop emergency auxiliary equipment cooling water system and a seawater system emergency auxiliary equipment cooling seawater system.Conventional emergency auxiliary equipment cooling equipment consists of residual heat removal equipment installed at nuclear power plants and other equipment. This equipment is provided to release heat generated by emergency equipment and common equipment necessary for normal operation of the power plant to the sea, which is a final heat sink.

That is, as shown in FIG. 2, the emergency auxiliary equipment cooling equipment of a nuclear power plant has a heat exchanger 4, a cooling water supply pipe 1, and a cooling water return pipe for returning the heat-exchanged cooling water to the heat exchanger 4. 2 and a cooling water pump 3 provided in the middle of the cooling water return pipe 2, a closed loop freshwater emergency auxiliary cooling water system A, a seawater pump 10 for supplying cooling seawater to the heat exchanger 4, and a cooling seawater Supply piping 11, and cooling seawater supply piping
A connecting pipe 16 having a gate valve 13 disposed between the connecting pipes 11 is connected to a seawater emergency auxiliary cooling seawater system B comprising a water discharge pipe 12 for returning the heat-exchanged cooling seawater to the sea. This emergency auxiliary equipment cooling equipment is composed of three systems as shown in FIG.

FIG. 2 will be described in more detail. In FIG. 2, reference numerals 1 and 2 respectively indicate a cooling water supply pipe and a cooling water return pipe through which the cooling water of the emergency auxiliary equipment cooling water system A circulates. The pipe 1 connects the heat exchanger 4 with the residual heat removing heat exchanger 5 which is the load to be cooled 5, the other emergency equipment 6, and the service equipment 7, and two cooling water return pipes 2 are connected in parallel from each equipment to be cooled. The cooling water pump 3 is connected to the heat exchanger 4 to form a closed loop as a whole.

[0005] The cooling water return pipe 2 of the residual heat removal heat exchanger 5
A valve 8 is installed in the cooling water supply pipe 1 and the return pipe 2 of the common equipment 7. For the seawater system emergency auxiliary cooling seawater system B, each heat exchanger 4 is connected to a cooling seawater supply pipe 11 and a water discharge pipe 12 connecting a seawater pump 10, and is further partitioned between the cooling seawater supply pipes 11. valve
A connecting pipe 16 in which 13 is arranged is connected.

In FIG. 2, reference numeral 17 denotes a switching valve device. The switching valve device 17 circulates the cooling water circulating through the emergency accessory cooling water system A via the heat exchanger 4 and bypasses the heat exchanger 4. The purpose is to balance the flow rate of the cooling water.

In a nuclear power plant, as shown in FIG. 3, the emergency auxiliary equipment cooling system having such a configuration is connected by a three-system tie line 18, and as a design heat removal performance in the event of an accident, Both systems have a heat removal capacity of 50%.
That is, the design is such that two of the three systems satisfy the required heat removal capability.

[0008] This is based on a single failure criterion, which is a basic concept of safety design in a nuclear power plant, in that even if one system fails due to some event, the function is satisfied with the remaining equipment, which is a basic concept of safety design in a nuclear power plant.

In the emergency auxiliary equipment cooling system having such a configuration, the cooling water supply pipes 1 and
The cooling water circulating in the cooling water return pipe 2 is cooled by the heat exchanger 4 and is cooled via the cooling water supply pipe 1 as a load to be cooled, a residual heat removal heat exchanger 5, other emergency equipment 6, a regular equipment 7. Supplied to

The cooling water, which has cooled the equipment to be cooled and raised in temperature, is returned to the heat exchanger 4 again through the cooling water return pipe 2 and the cooling water pump 3. The heated cooling water is heat-exchanged by the seawater supplied to the heat exchanger 4 via the cooling seawater supply pipe 11 by the seawater pump 10 and is discharged from the water discharge pipe 12 to the sea, which is a final heat release area. .

In such a configuration, the emergency auxiliary equipment cooling seawater system operates one pump and one heat exchanger in each system during normal operation, and two pumps and heat exchangers in each system during an accident. The operation of all two exchangers is required.

[0012]

The equipment of the emergency auxiliary equipment cooling equipment undergoes regular maintenance and inspection. In the conventional configuration, the cooling water during normal operation for each series is one pump 3 and the seawater pump
One unit 10 and one heat exchanger 4 are spares, which can be practically maintained and inspected. However, in the case of an emergency system, this spare cooling water pump 3, seawater pump 10, heat exchange The vessel 4 is a standby facility for an emergency.

In the unlikely event that a maintenance check is performed during normal operation,
If an accident occurs while the cooling water pump 3, seawater pump 10 and heat exchanger 4 are isolated, the heat removal capacity is insufficient,
Maintenance inspection during normal operation is basically not allowed.

Among the cooling water pump 3, the seawater pump 10, and the heat exchanger 4, the seawater pump 10 is a dynamic device of a seawater system, and is used to remove attached sea creatures, repair seawater corroded parts, and the like.
Active maintenance is required to ensure soundness, and the maintenance and inspection period is also long.

A case where a reactor accident occurs during maintenance and inspection of the seawater pump 10 during normal operation will be described with reference to FIG. FIG. 4 shows the emergency auxiliary equipment cooling seawater system B in FIG. 2, and reference numerals a and b in FIG. 4 denote equipment and piping of the first system and the second system. This is because a is the first and b is the second.

When performing maintenance and inspection of the first seawater pump 10a, the first seawater pump discharge valve 15a is closed to isolate the first seawater pump 10a, and the gate valve 13 is normally closed and the second seawater pump 10a is closed. The seawater pump 10b supplies cooling seawater to the second seawater heat exchanger 4b via a second seawater pump discharge pipe 14b and a second seawater supply pipe 11b. Also, the second
The cooling seawater heat-exchanged by the heat exchanger 4b is discharged to the sea through the second seawater discharge pipe 12b.

At this time, if a nuclear reactor accident occurs, the first
Further, since the second seawater pumps 10a and 10b do not have a spare, they have only a heat removal capability in a normal operation state, and cannot cool a required heat removal amount due to a nuclear reactor accident. The same applies to the case where the maintenance and inspection of the second seawater pump 10b is performed.

For this reason, the first and second seawater pumps 10
The maintenance and inspection of a and 10b are the periodic inspection of the nuclear power plant
Inspection of the first and second seawater pumps 10a and 10b takes a long time, and is a deciding factor in the number of regular inspection days. In view of reducing the number of regular inspection days, it is desired that the inspection of the seawater pump be performed during normal operation other than the regular inspection period.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and enables maintenance and inspection of a seawater pump to be performed during normal operation, thereby shortening a regular inspection period and providing a highly reliable nuclear power plant. An object of the present invention is to provide emergency auxiliary equipment cooling equipment.

[0020]

According to the first aspect of the present invention, there is provided the following:
And a cooling water supply pipe for supplying cooling water cooled by the second heat exchanger to a residual heat removal heat exchanger to be cooled, other emergency equipment and service equipment, and the residual heat removal heat exchanger. , A closed loop fresh water comprising a cooling water return pipe for returning the cooling water heat exchanged by the other emergency equipment and the service equipment to the first and second heat exchangers, and a cooling water pump provided on the cooling water return pipe System and the first
First and second seawater pumps for supplying cooling seawater to the first and second heat exchangers, first and second seawater supply pipes, and a first gate valve between the first and second cooling seawater supply pipes. Connecting the connected communication pipes, the first and second
In the emergency auxiliary cooling system comprising a seawater system comprising first and second water discharge pipes for returning the cooling seawater heat exchanged by the heat exchanger to the sea, first and second gate valves are provided between the communication pipes. Is installed, and a third valve is provided between the first gate valve and the second gate valve.
And a third seawater pump connected to the third discharge pipe via a discharge valve.

According to a second aspect of the present invention, there is provided the first to third seawater pumps 3 per system including the third seawater pump.
The system is characterized in that a switching system for periodically switching the units and operating the three seawater pumps one by one is provided.

According to a third aspect of the present invention, the first system comprises
If one of the three third seawater pumps is being maintained and inspected, a piping system is provided so that the remaining two can secure the required amount of cooling seawater during a reactor accident. It is characterized by becoming.

According to a fourth aspect of the present invention, any one of the first to third seawater pumps is used as an operating unit, a standby unit and a standby unit. An electric circuit is provided for sending a start signal to the standby unit when the standby unit fails to start. According to the present invention, the seawater pump can have a spare even in the event of an accident, so that maintenance and inspection of the seawater pump can be performed during normal operation.

That is, according to the present invention, two heat exchangers for cooling seawater and three seawater pumps are installed per system, and one seawater pump and one seawater heat exchanger are operated during normal operation. . For this reason, two seawater pumps and one seawater heat exchanger are prepared as standby machines in the event of an accident. Therefore, since the seawater pump has one extra spare, the function of the system can be satisfied even if the maintenance and inspection of the seawater pump is performed during the normal operation.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a cooling system for emergency auxiliary equipment of a nuclear power plant according to the present invention will be described with reference to FIG. FIG. 1 is a schematic system diagram of an emergency auxiliary equipment cooling seawater system in the emergency auxiliary equipment cooling equipment showing one embodiment of the present invention.

First and second heat exchangers 4a, 4 for cooling seawater
In order to supply cooling seawater to the first and second seawater pumps 10a and 10b, first and second seawater pump discharge valves 15 are provided.
a, 15b installed seawater pump discharge piping 14a, 14b, 14
c is connected, the first and second heat exchangers 4a, 4b are connected via seawater supply pipes 11a, 11b, and the cooling seawater heat-exchanged in the first and second heat exchangers 4a, 4b is Water discharge pipes 12a and 12b are connected for discharge to the sea. In a seawater-based emergency auxiliary cooling seawater system, two lines of such equipment are installed.

First and second seawater supply pipes 11a, 11b
Two first gate valves 13a and two second gate valves 13b are installed in the connecting pipe 16 connecting the first and second gate valves 13a and 13a.
A third seawater pump discharge pipe 14c to which a third seawater pump 10c is connected is branched and connected between 13b. Similarly, a third seawater pump discharge valve 15c is installed in the seawater pump discharge pipe 14. . In the emergency accessory cooling system for a nuclear power plant according to the present embodiment, the emergency accessory cooling seawater system having such a configuration is configured by three systems as shown in FIG.

Next, the operation of the present embodiment will be described. In the emergency auxiliary equipment cooling seawater system having such a configuration,
During normal operation, the first to third seawater pumps 10a, 10b, 10
The operation state of the system will be described for maintenance and inspection of three units c and when a reactor accident occurs at that time.

First, when performing maintenance and inspection of the first seawater pump 10a, the first seawater pump discharge valve 15a is closed to isolate the first seawater pump 10a, and the first gate valve 13a.
Open the second gate valve 13b and close the third seawater pump 10
c is the third seawater pump discharge pipe 14c, connecting pipe 16,
The first sea exchanger 4a is supplied with cooling seawater via the seawater supply pipe 11a, and the second seawater pump 10b is connected to the second seawater pump discharge pipe 14b and the second seawater supply pipe 11b.
Through which the cooling seawater can be supplied to the second seawater heat exchanger 4b.

During normal operation, one of the second and third seawater pumps 10b and 10c is operated to perform required heat removal. The first and second heat exchangers 4a, 4
The cooling seawater heat-exchanged in step b is discharged into the sea through the first and second seawater discharge pipes 12a and 12b.

At this time, if a nuclear reactor accident occurs,
Seawater pump 10b is connected to the second heat exchanger 4b and
Since the seawater pump 10c is in a state capable of supplying cooling seawater to the first heat exchanger 4a, the required heat removal amount at the time of the accident by the activation of the standby first or second seawater pump 10b or 10c. Can be removed.

Next, when performing maintenance and inspection of the second seawater pump 10b, the second seawater pump discharge valve 15b is closed to isolate the second seawater pump 10b, the second gate valve 13b is opened, and the first seawater pump 10b is opened. The gate valve 13a is closed and the first seawater pump 10a is closed.
Is the first seawater pump discharge pipe 14a, the first seawater supply pipe
A state in which cooling seawater can be supplied to the first heat exchanger 4a via the first sea exchanger 11a is provided, and the third seawater pump 10c is connected via the third seawater pump discharge pipe 14c, the communication pipe 16, and the second seawater supply pipe 11b. To a state where cooling seawater can be supplied to the second heat exchanger 4b.

During normal operation, one of the first and third seawater pumps 10a and 10c is operated to perform required heat removal. The first and second heat exchangers 4a, 4b
Cooling seawater heat-exchanged in the first and second seawater discharge pipes
Water is discharged into the sea via 12a and 12b.

At this time, if a reactor accident occurs, the seawater pump 10a can supply cooling seawater to the first heat exchanger 4a, and the third seawater pump 10c can supply cooling seawater to the second heat exchanger 4b. The first or third waiting
By starting the seawater pump 10a or 10c, the required heat removal at the time of an accident can be removed.

Finally, when performing maintenance and inspection of the third seawater pump 10c, the third seawater pump discharge valve 15c is closed to isolate the third seawater pump 10c, and the first and second gate valves 13a, 13a. 13b is closed and the first seawater pump 10a
Is the first seawater pump discharge pipe 14a, the first seawater supply pipe
The first sea exchanger 4a can be supplied with cooling seawater via the first sea exchanger 11a, and the second seawater pump 10b is connected to the second seawater pump discharge pipe 14b and the second seawater supply pipe 11b via the second seawater supply pipe 11b. The cooling seawater can be supplied to the heat exchanger 4b.

During normal operation, one of the first and second seawater pumps 10a and 10b is operated to perform required heat removal. The first and second heat exchangers 4a, 4
The cooling seawater heat-exchanged in b is discharged to the sea via the first and second seawater discharge pipes 12a and 12b.

At this time, if a nuclear reactor accident occurs, the first
Seawater pump 10a is connected to the first heat exchanger 4a and
Since the seawater pump 10b is in a state capable of supplying cooling seawater to the second heat exchanger 4b, the required heat removal amount at the time of the accident due to the activation of the standby first or second seawater pump 10a or 10b. Can be removed.

In the above embodiment, the first to third seawater pumps per system including the third seawater pump 10c
It is also possible to provide a switching system for periodically switching the three units 10a, 10b and 10c and operating the three seawater pumps one by one.

When any one of the first to third seawater pumps 10a, 10b, and 10c per system is under maintenance and inspection, the remaining two pumps are used when a reactor accident occurs. A piping system can be provided so that the required amount of cooling seawater can be secured.

Further, any one of the first to third seawater pumps is used as an operating unit, a standby unit and a standby unit, and when the standby unit is started due to a reactor accident, the normal standby unit is used. If the start-up fails, an electric circuit for sending a start-up signal to the standby unit and starting up may be provided.

When the maintenance of the first to third seawater pumps 10a, 10b, 10c is not carried out during the normal operation, that is, the first to third seawater pumps 10a, 10a, 10
In a state where three units b and 10c are operable, one unit is an operating unit, one unit is a standby unit, and one unit is a standby unit.

Here, the first seawater pump 10a is operated by an operating machine,
The second seawater pump 10b is used as a standby machine, and the third seawater pump 10c is used.
Is a standby unit, a start signal is sent to the second seawater pump 10b of the standby unit in the event of a nuclear reactor accident. By providing an electric circuit for detecting the failure of activation of the second seawater pump 10b of the stand-by unit for 10c and transmitting an activation signal, it is possible to have one spare even in the event of an accident.

According to the above embodiment, by installing one seawater pump and associated piping and valves in each system, maintenance and inspection of the seawater pump during normal operation becomes possible. Even if a nuclear reactor accident occurs, the function of the system can be maintained, and more spare water pumps will lead to improved reliability.

[0044]

According to the present invention, by installing a seawater pump and associated pipes and valves in each system, it is possible to perform maintenance and inspection of the seawater pump during normal operation. Cooling equipment can be provided.

As a result, the maintenance work of the seawater pump can be performed not during the regular inspection of the plant but during the normal operation, so that the period of the regular inspection can be shortened and the reliability of the seawater pump can be increased by increasing the number of spare water pumps. An emergency auxiliary equipment cooling system for a nuclear power plant can be provided.

[Brief description of the drawings]

FIG. 1 is a system diagram for explaining an embodiment of an emergency accessory cooling system for a nuclear power plant according to the present invention.

FIG. 2 is a system diagram showing a conventional emergency auxiliary equipment cooling facility of a nuclear power plant.

FIG. 3 is a system diagram showing an example in which three systems of emergency auxiliary equipment cooling equipment in FIG. 2 are connected.

FIG. 4 is a system diagram for explaining the problem of the emergency auxiliary equipment cooling seawater system in FIG. 2;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Cooling water supply piping, 2 ... Cooling water return piping, 3 ... Cooling water pump, 4 ... Heat exchanger, 4a ... First heat exchanger, 4b ...
Second heat exchanger, 5 ... Residual heat removal heat exchanger, 6 ... Other emergency equipment, 7 ... Service equipment, 8 ... Valve, 9 ... Valve, 10 ... Seawater pump, 10a ... First seawater pump, 10b: second seawater pump, 10c: third seawater pump, 11: seawater supply pipe,
12 ... water discharge pipe, 13 ... gate valve, 14 ... seawater pump discharge pipe,
15 ... seawater pump discharge valve, 16 ... connection piping, 17 ... switching valve device, 18 ... tie line.

Claims (4)

[Claims] A cooling water cooled by the first and second heat exchangers;
A cooling water supply pipe for supplying other emergency equipment and service equipment, and the first and second heat exchangers for the residual heat removal heat exchanger and the cooling water heat exchanged by the other emergency equipment and service equipment; And a closed loop freshwater system comprising a cooling water pump provided in the cooling water return pipe and the first and second heat exchangers for supplying cooling seawater to the first and second heat exchangers, respectively. A seawater pump, first and second seawater supply pipes, and a communication pipe having a first gate valve disposed between the first and second cooling seawater supply pipes are connected, and heat is supplied to the first and second heat exchangers. In an emergency auxiliary cooling system comprising a seawater system including first and second water discharge pipes for returning exchanged cooling seawater to the sea, first and second gate valves are installed between the communication pipes, The third valve between the first gate valve and the second gate valve An emergency auxiliary equipment cooling facility for a nuclear power plant, comprising a branch connection of a discharge pipe, and a third seawater pump connected to the third discharge pipe via a discharge valve. . 2. A switching system for periodically switching the three first to third seawater pumps per system, including the third seawater pump, and operating the three seawater pumps one by one. 2. The emergency auxiliary equipment cooling system for a nuclear power plant according to claim 1, further comprising: 3. In the case where one of the first to third seawater pumps is maintained and inspected for each of the three seawater pumps, the required cooling seawater at the time of a reactor accident is used for the remaining two pumps. 3. An emergency auxiliary equipment cooling system for a nuclear power plant according to claim 1, wherein a piping system is provided so as to secure an amount. 4. One of the first to third seawater pumps is set as an operation unit, a standby unit and a standby unit, and when the standby unit is started in response to a nuclear reactor accident, the normal standby unit is used. 4. An emergency auxiliary equipment cooling system for a nuclear power plant according to claim 1, further comprising an electric circuit for sending a start signal to said standby unit when the start-up fails, and for starting said standby unit.