JPS5939720B2 - Residual heat removal equipment - Google Patents

Description

[Detailed description of the invention] The present invention relates to a residual heat removal device for a boiling water nuclear reactor.

Generally, boiling water reactors are equipped with a residual heat removal device, which takes out the reactor water in the reactor pressure vessel and circulates it through a heat exchanger when the reactor is shut down, and removes the decay heat generated in the reactor core. It is configured to remove residual heat such as.

Conventionally, this residual heat removal apparatus was constructed as shown in FIG.

That is, 1 is a nuclear reactor pressure vessel, and a reactor core (not shown) is accommodated in this reactor pressure vessel 1.

Further, 2 is a reactor recirculation pump, and 3 is a reactor recirculation pipe.

A reactor water take-off pipe 4 is branched and connected to the reactor recirculation pipe 3, so that a portion of the reactor water can be taken out.

The reactor water taken out through this reactor water take-out pipe line 4 is transferred to a residual heat removal system heat exchanger 6 by a residual heat removal system pump 5.
It is configured to be sent to and cooled.

A part of the reactor water cooled by the residual heat removal system heat exchanger 6 is returned to the reactor recirculation line 3 via the reactor water return line 7, and the remaining reactor water is returned to the reactor water return line 3. It is configured to be returned directly into the reactor pressure vessel 1 via a line 8.

1. A pool water supply pipe 9 is branched and connected to the reactor water take-off pipe 4, and this pool water supply pipe 9 communicates with the pressure suppression pool 10 of the reactor containment vessel.

Further, a pool water return pipe 11 is branched and connected to the reactor water return pipe 8, and this pool water return pipe 11 communicates with the pressure suppression pool 10 described above.

When the reactor is shut down, the on-off valve 12 provided in the middle of the pool water supply pipe 9 and the on-off valve 13 provided in the middle of the pool water return pipe 11 are closed, and the reactor water An on-off valve 14 provided in the middle of the extraction pipe 4 and an on-off valve 15.1 provided in the middle of the reactor water return pipes 7 and 8
6 is opened, the residual heat removal system pump 5 is operated, and reactor water is circulated through the residual heat removal system heat exchanger 6 to remove residual heat generated in the reactor core.

Furthermore, since this residual heat removal device is not operated for a long period of time during operation of a nuclear reactor, a test operation called a surveillance operation is periodically performed to confirm its function.

During such surveillance operations, the reactor water can only be circulated, so the on-off valve 1 of the reactor water take-out pipe 4 is closed.
4 and reactor water return pipe γ.

The on-off valves 15 and 16 of 8 are closed, and the on-off valve 12 of the pool water supply pipe 9 and the on-off valve 13 of the pool water return pipe 11 are opened to operate the residual heat removal system pump 5,
The pool water 17 in the pressure suppression pool 10 is circulated through the pool water supply pipe 9 and the pool water return pipe 11 to perform the above-mentioned surveillance operation.

After this surveillance operation is completed, the reactor water take-out pipe 4, the residual heat removal system heat exchanger 6, the reactor water return pipe 7,
The pool water remaining inside the pools 8, etc. is left in a full state without being drained, and so-called full water storage is performed to prevent the inner surfaces of these pools from being exposed to air and oxidizing.

However, the pool water 17 in the pressure suppression pool 10 generally contains a high concentration of dissolved oxygen close to saturation, and even if the water is stored at full capacity as described above, the reactor water take-out pipe 4 still A considerable amount of rust occurs on the inner surfaces of the removal system heat exchanger 6, reactor water return pipes 7'', 8, etc.

When the next reactor shuts down and this residual heat removal device is operated, this rust is carried into the reactor pressure vessel 1 along with the circulating reactor water, adheres to the surfaces of the fuel rods, etc., and removes the fuel. There were other problems, such as having a negative impact on the soundness and the rust becoming radioactive and becoming so-called radioactive cladding.

The present invention has been made based on the above circumstances, and its purpose is to minimize the occurrence of rust on the inner surface of pipes, etc. during stoppage and storage, and to prevent the occurrence of adverse effects on the integrity of the fuel due to this rust and the occurrence of radioactive crud, etc. The object of the present invention is to obtain a residual heat removal device that can reduce the amount of residual heat.

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

In the figure, 101 is a reactor pressure vessel, and a reactor core (not shown) is accommodated within this reactor pressure vessel 101.

Further, 102 is a reactor recirculation pump, and 103 is a reactor recirculation pipe.

A reactor water extraction pipe 104 is branched and connected to the reactor recirculation pipe 103 on the suction side of the reactor recirculation pump 102, and reactor water is taken out through the reactor recirculation pipe 103. It is configured as follows.

An on-off valve 12 is located in the middle of this reactor water extraction pipe 104.
9 and a residual heat removal system pump 105.
The extracted reactor water is transferred to the residual heat removal system heat exchanger 106 by this residual heat removal system pump 105.
is configured to be sent to.

The reactor water sent to the residual heat removal system heat exchanger 106 is configured to be cooled by exchanging heat with a coolant sent from the outside.

A portion of the reactor water cooled by the residual heat removal system heat exchanger 106 is transferred to the reactor water return pipe 107 and the on-off valve 10.
8 to the reactor recirculation line 103 on the discharge side of the reactor recirculation pump 102, and the remaining reactor water is returned directly to the reactor pressure vessel 101 via the reactor water return line 109 and the on-off valve 110. It is configured to be placed back inside.

In addition, the above-mentioned reactor water take-out pipe 104 includes a pool water supply pipe 1.
11 is branched and connected, and this pool water supply pipe 11
1 communicates with the pressure suppression pool 112 of the reactor containment vessel.

Note that there is an on-off valve 1 in the middle of this pool water supply pipe 111.
13 are provided.

Further, a pool water return pipe 114 is branched and connected in the middle of the reactor water return pipe 109, and this pool water return pipe 11
4 communicates with the pressure suppression chamber 112.

An on-off valve 115 is provided in the middle of this pool water return pipe 114.

Further, 116 is a deaerated water tank, and a predetermined amount of deaerated water 117 is stored in this deaerated water tank 116.

A vacuum pump 118 is installed in this deaerated water tank 116.
is connected to the degassed water tank 116, and is configured to evacuate the inside of this degassed water tank 116 and degas dissolved oxygen, etc. in the water stored inside.

A warm air water supply pipe 119 is branch-connected to the reactor water take-off pipe 104 at a location upstream from the location where the pool water supply pipe 111 is branch-connected, and this deaerated water supply pipe 119 communicates with the degassed water tank 116.

An on-off valve 1 is provided in the middle of this deaerated water supply pipe 119.
20 is provided, and deaerated water 1 in the deaerated water tank 116 is provided.
17 to the reactor water extraction pipe 104.
1 is provided.

Further, degassed water return pipes 122 and 123 are branched and connected to the reactor water return pipes 107 and 109, respectively, and these degassed water return pipes 122 and 123 are connected to one degassed water collection return pipe The degassed water tank 11
It is connected to 6.

On-off valves 126 and 127 are provided in the middle of the degassed water return pipes 122 and 123, respectively, and in the middle of the degassed water collection and return pipe 124, the concentration of dissolved oxygen in the water flowing through the pipe is provided. A dissolved oxygen concentration detector 128 is provided to measure the dissolved oxygen concentration.

In one embodiment of the present invention configured as described above, the on-off valve 12g of the reactor water outlet pipe 104 is used when the reactor is shut down.

The on-off valves 108 and 110 of the reactor water return pipes 107 and 109 are opened, and the on-off valve 11 of the pool water supply pipe 111 is opened.
3. On-off valve 115 of pool water return pipe 114, on-off valve 120 of deaerated water supply pipe 119, and deaerated water return pipe 122
, 123 are closed, and the residual heat removal system pump 105 is operated.

Therefore, the reactor water is circulated through the reactor water take-off pipe 104, the residual heat removal system heat exchanger 106, and the reactor water return pipes 107 and 109 to remove residual heat such as decay heat generated in the reactor core.

During reactor operation, the reactor water extraction pipe 104
and the on-off valves 108 and 110 of the reactor water return pipes 107 and 109 are closed, and the on-off valve 113 of the pool water supply pipe 111 and the pool water return pipe 114 are closed.
The on-off valve 115 is opened, the residual heat removal system pump 105 is operated to circulate the pool water 130 in the pressure suppression pool 112, and a surveillance operation of this residual heat removal device is performed.

When this surveillance operation is completed, the on-off valve 113 of the pool water supply pipe 111, the pool water return pipe 11
The on-off valve 115 of No. 4 is closed and the degassed water supply pipe 1 is closed.
19 on-off valve 120 and deaerated water return pipes 122, 12
Open the on-off valves 126 and 127 of 3 to deaerate water pump 12.
1 and the residual heat removal system pump 105 are operated to circulate the degassed water 117 in the degassed water tank 116.

Therefore, the pool water 130 remaining in the reactor water take-out pipe 104, residual heat removal system heat exchanger 106, and reactor water return pipes 107, 109 is replaced with degassed water 117 with a low dissolved oxygen concentration. .

When the remaining pool water 130 is completely replaced with deaerated water 117, the on-off valves 120, 126, 127
The reactor water take-off pipe 104, the residual heat removal system heat exchanger 106, and the reactor water return pipes ml 07 and 10.9 are filled with degassed water and stored at full capacity.

Since this degassed water 117 has a low dissolved oxygen degree, rust is prevented from forming on these inner surfaces during storage.

In this embodiment, since the dissolved oxygen concentration detector 128 is provided in the degassed water collection and return pipe 124, the dissolved oxygen concentration detector 128 allows the degassed water collection and return pipe 1 to be detected.
By measuring and monitoring the dissolved oxygen concentration of the water flowing through the pool 24, it is possible to detect whether the pool water 130 has been completely replaced by the degassed water 117.

Further, the degassed water supply pipe 119 is branched and connected to the reactor water take-out pipe 104 on the upstream side of the branch connection point of the pool water supply pipe 111, and the degassed water return pipes 122 and 123 are pool water return pipes. Since the reactor water return pipes 107 and 109 are connected to the reactor water return pipes 107 and 109 on the downstream side of the branch connection point of the line 114, the remaining pool water 130 can be completely replaced with the degassed water 117 without leaving any residue.

As described above, the present invention provides a deaerated water tank for storing deaerated water, and supplies 8 J of deaerated water from the deaerated water supply line and the reactor water return line that supply this deaerated water to the reactor water take-out line. 'e A degassed water return pipe is provided to return the air and water to the tank.

Therefore, after conducting a surveillance operation of this residual heat removal device using the pool water in the pressure suppression pool, the degassed water in the degassed water tank is supplied via the degassed water supply pipe and the degassed water return pipe. The remaining pool water with a high dissolved oxygen concentration can be replaced with degassed water with a low dissolved oxygen concentration and stored at full capacity.

In addition, the degassed water supply pipe is branched and connected to the reactor water take-out pipe on the upstream side of the branch connection point of the pool water supply pipe, and the deaerated water return pipe is branched and connected to the pool water return pipe branch connection point. Since it is branched and connected to the reactor water return pipe on the downstream side, it is possible to completely replace residual pool water with degassed water without leaving any residual pool water.

Therefore, rust is prevented from forming on the inner surfaces of the reactor water take-out pipe, residual heat removal system heat exchanger, reactor water return pipe, etc. during storage, and such rust is carried into the reactor pressure vessel. Its effects are outstanding, such as being able to effectively prevent problems such as adverse effects on the integrity of the fuel and an increase in the amount of radioactive crud generated.

[Brief explanation of the drawing]

FIG. 1 is a schematic system diagram of a conventional example, and FIG. 2 is a schematic system diagram of an embodiment of the present invention. 101... Reactor pressure vessel, 104...
・Reactor water extraction pipe, 105...Residual heat removal system pump, 106...Residual heat removal system heat exchanger, 107
, 109... Reactor water return pipe, 112...
- Pressure suppression pool, 111...Pool water supply pipe, 114...Pool water return pipe, 116...
...Deaerated water tank, 117... Deaerated water, 1
19... Degassed water supply pipe, 122, 123...
...Deaerated water return pipe.

Claims (1)

[Claims] 1. A residual heat removal system pump, which communicates the suction side of the residual heat removal system pump with the inside of the reactor pressure vessel to extract reactor water from the reactor pressure vessel and supply it to the residual heat removal system pump. A residual heat removal system heat exchanger that cools the reactor water sent by the extraction pipe and the residual heat removal system pump, and a residual heat removal system heat exchanger that cools the reactor water cooled by the residual heat removal system heat exchanger into the above reactor pressure vessel. The reactor water return pipe is branch-connected to the reactor water take-out pipe and communicated with the pressure suppression pool of the reactor containment vessel, and supplies the pool water in the pressure suppression pool to the residual heat removal system pump. a pool water supply pipe, a pool water return pipe that is branch-connected to the reactor water return pipe and communicates with the pressure suppression pool to return pool water to the pressure suppression pool; and a pool water return pipe that stores deaerated water. A vacuum pump that evacuates the inside of this deaerated water tank and deaerates the water stored inside, and the above-mentioned furnace at a point upstream from the branch connection point of the pool water supply pipe. A degassed water supply pipe that is branch-connected to the water take-out pipe and communicates with the degassed water tank and supplies the degassed water in the degassed water tank to the residual heat removal system pump, and the pool water A degassed water return branch is connected to the reactor water return pipe at a point downstream from the branch connection point of the return pipe and communicates with the degassed water tank to return the degassed water to the degassed water tank. A residual heat removal device characterized by comprising a pipe line.