JPH0150876B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a control rod drive hydraulic device that drives control rods of a boiling water reactor up and down.

In general, boiling water reactors are equipped with a hydraulic control rod drive mechanism at the bottom of the reactor pressure vessel that houses the reactor core, and the control rod drive mechanism is driven by water pressure to move the control rods up and down into the reactor core. ing.

A conventional control rod drive hydraulic system is, for example, as shown in FIG. 1, and an outline of this conventional example will be explained below. That is, a large number of hydraulic control rod drive mechanisms c (only one is shown as a representative) are provided in the lower part of the reactor pressure vessel b containing the reactor core a. This control rod drive mechanism c moves a piston d up and down using water pressure, and is connected to an insertion pipe e and a withdrawal pipe f for press-fitting driving water. In addition, the above-mentioned insertion pipe e and withdrawal pipe f
A drive water supply pipe h and a discharge pipe i are connected to the drive water supply pipe h and the discharge pipe i via a directional switching valve g. Further, an accumulator k for accumulating scram water pressure is connected to the insertion pipe e via an inlet side scram valve j, and a scram water discharge container m is connected to the extraction pipe f via an outlet side scram valve l. ing. Also,
This scram water discharge container m is provided with a vent valve n and a drain valve p.

These vent valves n, drain valves p, and scram valves j and l described above are each controlled to open and close by air from a control air source r supplied through a control air piping q, and the control By applying the control air pressure, the scram valves j and l are kept closed against the spring pressure, and the vent valve n and drain valve p are kept open by the control air pressure. It's getting old. Further, the control air piping q is provided with air relief valves S ₁ , S ₂ , S ₃ and backup air relief valves _{t 1 , t 2 .} S ₃ , t ₁ , t ₂
is activated by the scram signal output at the time of emergency shutdown of the reactor to release the air in the control air pipe q, and due to this air release, the scram valves j and l are automatically activated by spring pressure. The vent valve n and drain valve p are automatically closed. Therefore, during scram, the scram water stored in the accumulator k is sent at high pressure to the insertion pipe e through the inlet side scram valve j, the piston d is raised, and the control rods U are moved into the reactor core a.
Insert rapidly. Moreover, the scram water discharged at this time is discharged into the scram water discharge container m through the outlet side scram valve l. When the scram operation is finished, a scram reset is performed to stop the air discharge from the control air pipe q, close the scram valves j and l, open the vent valve n and the drain valve p, and close the scram water discharge container. The scram drainage water collected in m is discharged.

As described above, in the conventional control rod drive hydraulic system, the scram valves j and l are automatically opened by releasing the air pressure from the control air pipe q. Therefore, in the event that control air is no longer supplied to the scram valves j and l due to a malfunction in the control air source r or a break in the control air piping q while the scram operation is on standby, It is conceivable that the scram valves j and l open even though the scram signal is not output, scram water is fed to the insertion pipe e, and the control rod u is inserted into the reactor core a. In this case, there was a possibility that the operating rate of the reactor would be significantly reduced, and the reliability of the reactor would be impaired.

This invention was made based on the above-mentioned circumstances, and its purpose is to be able to secure control air pressure for the scram valve even if the supply of control air is lost due to an accident, etc. An object of the present invention is to provide a control rod-driven hydraulic device that can prevent valves from opening during periods of time.

That is, the present invention provides a check valve for preventing backflow of control air on the upstream side of the air relief valve located at the most upstream position among the air relief valves provided in the control air piping. This is a control rod drive hydraulic device that can secure control air pressure for the scram valve even if the supply of control air runs out.

The present invention will be explained below based on an embodiment shown in FIG. 1 in the figure is the reactor pressure vessel,
It has a reactor core 2 inside. In addition, a hydraulic control rod drive mechanism 3 (1
The control rod drive mechanism 3 moves the control rods 4 into the reactor core 2.
It is now possible to move up and down.

The control rod drive mechanism 3 includes a piston 5 that can be raised and lowered, and this piston 5
An insertion pipe 6 that supplies driving water to raise the piston 5 is connected to an extraction pipe 7 that supplies driving water to lower the piston 5. Further, a drive water supply pipe 10 and a discharge pipe 11 are connected to the insertion pipe 6 and the withdrawal pipe 7 via a directional switching valve 9. Further, a cooling water supply pipe 12 is connected to the insertion pipe 6, so that cooling water for cooling the control rod drive mechanism 3 can be supplied to the insertion pipe 6 during normal reactor operation.

Further, an accumulator 14 for accumulating scram water pressure is connected to the insertion pipe 6 via a scram water supply pipe 13. This accumulator 1
4 is a pressure vessel 15 filled with pressurized gas such as nitrogen
and a water container 16 containing scram water. 17 is a filling water piping for replenishing filling water during scram, and this filling water piping 1
7, the driving water supply pipe 10, and the cooling water supply pipe 12 described above are connected to a water source (not shown) via a driving water pump 18.

An inlet side scram valve 20 is provided in the scram water supply pipe 13. This scram valve 20
The valve is opened and closed by control air pressure, and when control air pressure is applied, the valve remains closed against spring pressure, and when air pressure is released, the spring automatically closes the valve. The valves are starting to open. Reference numeral 21 denotes a control air pipe for supplying control air, and compressed air is sent to this air supply source 21 from a control air source 22. The above control air piping 21
Air relief valves 23 and 24, also called scram pilot valves, are provided in the middle of the scram valve side piping 21a connected to the scram valve 20. Furthermore, air relief valves 25 and 26 for backup are provided in series on the upstream side of these air relief valves 23 and 24. The air relief valves 23, 24 and the backup air relief valves 25, 26 are used in pairs to ensure reliable operation. Further, a bypass pipe 27 is provided to bypass one of the backup air relief valves 26. This bypass pipe 27 has a function of distributing air so that when both of the backup air relief valves 25 and 26 operate to release air, air is also released from the other backup air relief valve 25. have

On the other hand, the extraction pipe 7 has a scram water discharge pipe 29.
is connected, and this scram water discharge pipe 29 is provided with a scram valve 30 on the outlet side. This scram valve 30 is the scram valve 2 on the inlet side described above.
0, the control air pressure sent from the control air piping 21 can maintain the valve closed state against the spring pressure.

A scram water discharge container 31 is connected via this outlet side scram valve 30. This scram water discharge container 31 is provided with a vent valve 32 and a drain valve 33. These vent valves 32 and drain valves 33 are connected to control air piping 21, respectively.
The scram water discharge container side piping path 21b which is a part of
is connected, and in the middle of this piping path 21b,
Pilot scram valve or air relief valve 34
is provided. The vent valve 32 and drain valve 33 are maintained in an open state by applying control air pressure against spring pressure, and when the control air pressure is released, the spring pressure opens the vent valve 32 and the drain valve 33. The valve is designed to close automatically. In addition, the scram water discharge container 31
A piping 35 for introducing scram discharge water from a control rod drive mechanism of another system is also connected to.

A check valve 36 is provided in the control air piping 21 between the air relief valve 25, which is located on the upstream side of the air relief valves 25 and 26, and the air supply source 22. This check valve 36 is connected to the air supply source 22.
Control air sent from the air relief valve 25, 2
It can be opened only in the direction in which the control air flows into the air supply source 22 side, and has the function of preventing control air from flowing back into the air supply source 22 side.

Next, the operation of the control rod drive hydraulic system having the above configuration will be explained. When inserting the control rods 4 into the reactor core 2, the driving water sent from the driving water pump 18 is
It is force-fed to the lower surface side of the piston 5 via the directional control valve 9 and the insertion pipe 6. Therefore, the control rods 4 are connected to the reactor core 2.
is inserted into the reactor, and the nuclear reaction is suppressed.

On the other hand, when withdrawing the control rods 4 from the reactor core 2,
The directional switching valve 9 is switched to send the driving water sent from the driving water pump 18 to the drawing pipe 7. This driving water is press-fitted into the upper surface of the piston 5 and pushes the piston 5 down. Therefore, the control rod 4 can be pulled out from the reactor core 2.

In addition, during an emergency shutdown of the reactor, the scram signal output from the reactor protection system circuit activates the air relief valves 23, 24, and 34 and the backup air relief valves 25 and 26 to release the air to the atmosphere. , the air in the control air piping 21 is released.
Therefore, the vent valve 32 and drain valve 33 of the scram water discharge container 31 are automatically closed because the control air pressure is eliminated. On the other hand, scram valve 2
0 and 30 automatically open when the control air pressure is released.

Therefore, the scram water stored in the accumulator 14 is sent to the insertion pipe 6 through the scram valve 20 on the inlet side by the pressure of the high pressure gas in the pressure vessel 15, and the piston 5 is pushed up. The rod 4 is quickly fully inserted into the reactor core 2, and the reactor operation is stopped. At this time, the scram water discharged from the drawing pipe 7 passes through the scram valve 30 on the outlet side and is stored in the scram water discharge container 31.

After the scram operation is completed, a scram reset is performed to reset the scram valves 20 and 30 again.
Control air pressure is applied to the vent valve 32 and drain valve 33, and at the same time the scram valves 20 and 30 close, the vent valve 32 and drain valve 33 open, and the scram discharge water stored in the scram water discharge container 31 is discharged. It is discharged through the drain valve 33. Then, the scram water discharge container 31 becomes empty and the scram operation standby state is resumed.

In this way, the control rod drive hydraulic system includes the scram valves 20, 30, the vent valve 32, and the drain valve 3.
The operation of step 3 is controlled by control air. Therefore, in the unlikely event that the control air source 22 malfunctions or the control air piping 2
If control air is no longer supplied to the scram valves 20, 30, etc. due to breakage of the scram valve 1, the scram valves 20, 30 may open.

However, according to the above-mentioned control rod drive hydraulic system, since the check valve 36 for preventing backflow of control air is provided upstream of the air relief valve 25, the problem that occurs upstream of the check valve 36 In the event of a breakage accident, the air pressure inside the control air piping 21 can be maintained, and the scram valves 20, 30 and vent valve 3
2. It is possible to prevent the drain valve 33 and the like from operating undesirably. Therefore, there is no possibility of an erroneous scram operation being performed, and it is possible to improve the reliability and operation rate of the nuclear reactor.

Further, the check valve 36 includes each air relief valve 23,
The air relief valves 23, 24, 25, 26, and 34 are activated during a scram because they are provided upstream of the backup air relief valve 25, which is the most upstream of the air relief valves 24, 25, 26, and 34. The check valve 36 does not obstruct the release of air at all, and scram operation can be performed in the same manner as a conventional control rod drive hydraulic system.
In addition, an air relief valve 2 is provided in the control air piping 21.
Air relief valve 2 located on the downstream side among 5 and 26
Since the bypass pipe 27 that bypasses the air release valve 25 is connected, air can also be released from the air relief valve 25, and the scram valve can be opened in a short time.

As explained above, the present invention includes an accumulator for scram water pressure accumulation connected to the insertion pipe of a hydraulic control rod drive mechanism via a scram water supply pipe, and a scram water discharge pipe connected to the extraction pipe of the control rod drive mechanism. A scram water discharge container connected to the scram water discharge container, a scram valve that is installed in the scram water supply piping and the scram water discharge piping and opened and closed by air pressure, and air for opening and closing control is supplied to these scram valves via a control air piping. and a first air supply source provided in series with the control air piping.
and a second air relief valve;
A check valve is provided between the air relief valve located on the upstream side of the air relief valve and the air supply source, and the first and second air relief valves are connected to the control air piping. It is equipped with bypass piping that bypasses the air relief valve located on the downstream side. Therefore, even if the air supply from the air supply source stops due to an accident or the like, the control air pressure for the scram valve can be secured, the scram valve can be prevented from opening inadvertently, and the first and second Air can be vented to the atmosphere from both of the second air relief valves. Therefore, malfunction of the scram valve can be prevented, and the scram valve can be opened in a short time, and the reliability of the control rod drive hydraulic system can be greatly improved.

[Brief explanation of drawings]

FIG. 1 is a system diagram showing a conventional control rod drive hydraulic system, and FIG. 2 is a system diagram of a control rod drive hydraulic system showing an embodiment of the present invention. 3... Control rod drive mechanism, 6... Insertion piping, 7...
... Pulled piping, 13 ... Scram water supply piping, 14
... Accumulator, 20 ... Scram valve, 21
...Control air piping, 23, 24, 25, 26...
...Air relief valve, 29...Scram water discharge piping,
30... Scram valve, 31... Scram water discharge container, 34... Air relief valve, 36... Check valve.

Claims (1)

[Claims] 1 An accumulator for scram water pressure accumulation connected to the insertion piping of the hydraulic control rod drive mechanism via a scram water supply piping, and an accumulator for scram water pressure accumulation connected to the extraction piping of the control rod drive mechanism via a scram water discharge piping. a discharge container, scram valves provided in the scram water supply piping and scram water discharge piping and opened and closed by air pressure, and an air supply source that supplies air for opening and closing control to these scram valves via control air piping; Between first and second air relief valves provided in series in the control air piping, and between the air relief valve located on the upstream side of these first and second air relief valves and the air supply source. and a bypass piping connected to the control air piping and bypassing an air relief valve located on the downstream side of the first and second air relief valves. control rod-driven hydraulic equipment.