JPS61202190A - Nuclear power generation main steam separation valve test apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a main steam isolation valve for nuclear power generation equipment, and is particularly suitable for preventing erroneous closing during an operation test of a main steam isolation valve during operation. This relates to main steam isolation valve testing equipment.

[Background of the invention]

Main steam isolation valves are installed in nuclear power reactors.

The function of the main steam isolation valve 1 will be explained with reference to FIG.

In the case of a boiling water reactor, main steam generated in the reactor 2 is sent to the turbine via the main steam pipe 3. In order to prevent radioactive materials generated in the event of a nuclear reactor accident from being released outside the reactor containment vessel 4, the main steam isolation valve is configured to automatically close in response to an accident signal. Normally, this main steam isolation valve 1 is installed inside and outside the reactor containment vessel in order to ensure redundancy. In the case of a pressurized water reactor, it is installed on the exit side of the steam generator in the reactor containment vessel, and has almost the same function as a boiling water reactor.

The main steam isolation valve 1 is normally operated fully open, but
In order to confirm its operation, tests are periodically conducted during operation in which the valve is closed by 10% from fully open (that is, 90% opening). If the main steam isolation valve accidentally closes completely during this periodic test, there are cases where the reactor automatically shuts down.
This is a major impediment to continued continuous operation of nuclear reactors. The main steam isolation valve mentioned above has a globe-shaped valve body and is generally driven by pneumatic pressure.

Referring to Figures 5-7, the main steam isolation valve is fully opened.

We will explain the operation when fully open and test closed.

FIG. 5 is an explanatory diagram of the driving air cylinder 7 for opening and closing the main steam isolation valve and its control mechanism, in which the air cylinder 7 contracts (the piston 6 rises) and the main steam isolation valve ( (not shown) is fully opened (normal operating state).

The disc of the main steam isolation valve is located below the shaft 5 which is fixed to the piston 6. Upper chamber of air cylinder 7 (
cylinder bottom chamber) and lower chamber (cylinder head chamber)
Air piping 8°9 is connected to each of the air pipes 8 and 9, which communicate with air pilot valves.

In the fully open state of the main steam isolation valve shown in FIG. 5, compressed air of approximately 7 Kp/crl flows from the main air supply source to the first quick-closing pilot valve 10. Second pilot valve 11. It is supplied to the lower chamber of the cylinder 7 via the third pilot valve 12 and the test pilot valve 13, and holds the piston 6 at the fully open position. On the other hand, the upper chamber of the cylinder 7 is connected to a pilot valve 10 via a pipe 8, and is evacuated (atmospheric pressure) as shown in FIG.

Next, FIG. 6 shows the state of the drive mechanism when the main steam isolation valve automatically closes. Upon receiving the automatic close signal, the pilot air stop valves 14, 15 open first. As a result, pilot air is exhausted from the quick-closing pilot valves 10, 11, 12 via the pilot piping 16, and each pilot valve 10, 11, 12 is pushed by the valve spring and changes from the state shown in FIG. Switch to the state shown in Figure 6. Therefore, the air in the lower chamber of the cylinder 7 is exhausted via the pilot valves 11, 12, and the compressed air (as shown in the figure as the main air supply) is passed from the main air supply source to the upper chamber of the cylinder 7 via the pilot valve 10. ) is supplied.

As a result, the piston 6 rapidly moves downward, pushing down the shaft 5 and completely closing the main steam isolation valve.

On the other hand, FIG. 7 shows the state during the operation test.

When a test signal is issued by the test switch 17, the three-way test solenoid valve 18 is switched and pilot air is supplied to the test pilot valve 13. As a result, as shown in FIG. 7, the air in the lower chamber of the cylinder 7 is exhausted via the pilot valves 12, 13, and the piston 6 moves downward. A throttle valve 19 is installed in the exhaust line of the test pilot valve 13, and the piston 6 during the operation test is
The descending speed is adjusted.

A limit switch 20 is provided on the piston shaft 5, which detects the 90% valve opening position and issues a signal.

When the piston 6 descends, the limit switch 20 operates, and the test switch 17 returns to its normal state, the test electromagnetic valve 18 returns to its normal state. Then, the test pilot valve 13 also returns to its normal position, and the piston 6 moves upward to become fully open.

When performing the operation test of the main steam isolation valve mentioned above, if all the functions of each device are normal, the main steam isolation valve will close to the 90% open state and then automatically return to the fully open state. However, if one of the failures (a) to (d) falls or there is an abnormality, the main steam isolation valve may close unexpectedly or may not return to the fully open state. This led to the shutdown of the nuclear reactor.

(a) If the test switch 17 is held in the test position incorrectly or is stuck in the test position due to a malfunction of the switch, (b) If the limit switch 20 does not operate at 90% opening, (C) Test 3 (d) When the test pilot valve 13 becomes stuck in the test position. There are actual cases where reactor operation and power generation have been interrupted due to these problems, and how to improve them. Action is necessary and urgent.

Furthermore, even if there is a leak in the exhaust seat A (see Figures 5 and 7) of the quick-closing pilot valve 11, compressed air will be supplied from the main air supply source to compensate for the leak when the main steam isolation valve is fully open. However, during the test, the main air supply to the pilot valve 12 is cut off, so the air in the lower chamber of the cylinder 7 is also exhausted from this seat part A, so the piston 6
There is a risk that this will cause a downward fluctuation in the amount of water, leading to an automatic shutdown of the reactor.

In order to solve the above-mentioned problems, the Japan Institute of Invention and Innovation published technical report 84
The technique of No.-009359 is known. However, in the above invention, it is still difficult to guarantee normal test operations (reliable restoration of the main steam isolation valve to full open) with sufficient reliability in all of the conditions (a) to (d).

[Purpose of the invention]

The present invention has been made in view of the above-mentioned circumstances, and after temporarily operating the main steam isolation valve in the closed direction on a trial basis, the present invention is reliably restored to the fully closed state, which may hinder the normal operation of nuclear power generation. The aim is to provide a test device that is free from any risks.

[Summary of the invention]

In order to achieve the above object, the test device of the present invention is designed for use in nuclear power generation, which controls the pressure air supplied to the air cylinder that opens and closes the main steam isolation valve through a quick-closing pilot valve and a test pilot valve. In the main steam isolation valve test device, a port of the air cylinder is located at a position opposite to the piston of the air cylinder in an intermediate state between when the main steam isolation valve is fully opened and when the main steam isolation valve is fully closed. and this port is connected to the test cylinder.

[Embodiments of the invention]

Next, one embodiment of the present invention will be described with reference to FIGS. 1 and 2. The air cylinder 7' shown in these two figures is a component corresponding to the air cylinder 7 (FIGS. 5 to 7) in the above-mentioned known example, but the air cylinder 7' of this embodiment
A bow) 7C is provided between the port 7a communicating with the conduit 8 and the port 7b communicating with the conduit 9, and this port 7c
The test pilot valve 22 is communicated with the test pilot valve 22 via a conduit 25.

FIG. 1 is an explanatory diagram showing the operation of the main steam isolation valve drive/control mechanism according to the present invention, when the main steam isolation valve is in a fully open state.

Compressed air from a main air supply (shown as main air supply in FIG. 1) is supplied to quick-closing pilot valves 10, 11.
12 to the test pilot valves 21, 22 in parallel, and then to the lower chamber of the cylinder 7 through the air pipe 9.

This keeps the piston 6 in the fully open position.

On the other hand, an air pipe 25 is connected to the 90% opening position of the cylinder, which is connected to the test pilot valve 21.2.
2 as shown in FIG. Further, the air pipe 8 in the upper chamber of the cylinder 7 is connected to a quick-closing pilot valve 10 for exhaust, as in the conventional example.

Figure 2 shows the operation of the main steam isolation valve during an operational test.

When a test signal is issued by the test switch, the test three-way solenoid valves 23, 24 are switched, and the test pilot valves 21, 22 are brought into the state shown in FIG. In this state, the main air supply to the lower chamber of the cylinder 7 is cut off, and compressed air is supplied to the lower part of the piston 6 from the 90% position of the cylinder via the air pipe 25, the test pilot valves 21 and 22, and the throttle valve 19. After being evacuated, the piston reaches the 90% open position at a predetermined downward speed. When the piston reaches the 90X' opening position, the air pipe 25 is blocked by the piston, so the piston automatically stops at this position regardless of the state of the test pilot valve. After confirming that the main steam isolation valve opening degree is 90%, when the test switch is returned to the normal position, the test three-way solenoid valves 23, 24 and the test pilot valves 21, 22 are also returned to their normal positions. At this time, even if either the test three-way kick valve or the test pilot valve is stuck, the main steam isolation valve can return to the fully open state.

Furthermore, since the limit switch is not expected to operate at the 90% position, there is no need to consider whether the limit switch is stuck.

Also, during the test, the quick-close pilot valve 12 is kept at a high pressure in the valve chamber, and even if there is a leak in the exhaust seat, the piston descending speed during the operation test is not affected and remains constant.

In addition, when a fully closed test is to be performed depending on the closing speed of the operation test, the same test as the conventional test can be performed by fully opening the stop valve 26.

Next, an embodiment in which the quick-closing pilot valve is shared with the main steam isolation valve will be described with reference to FIG.

FIG. 3 shows the case where there are four main steam pipes 3, and shows the isolation valves inside or outside the reactor containment vessel. The quick-closing air circuit 27 includes quick-closing pilot valves 10, 11.12 and pilot air stop valves 14.12 similar to those in FIG.
15 (all not shown) is installed in such a way that it is shared by each main steam isolation valve 1. Test air circuit 2
8 is a test pilot valve 2 similar to that shown in FIG.
1.22, a three-way solenoid valve for testing 23.24, and a throttle valve 19 (all not shown) are installed for each main steam isolation valve.

In the event of an accident, each main steam isolation valve 1 should be quickly closed at the same time, and a quick-closing pilot valve may be shared, and reliability is improved by reducing the number of high-lot valves 10, 11, 12 and pilot air stop valves. will improve. Further, the operation test must be performed for each main steam isolation valve, and the test air circuit 28 cannot be shared by each main steam isolation valve.

The inventor of the present invention has experimentally confirmed that the device of the above-described embodiment has an effect similar to that of an upstart.

(1) Test switch, 90% opening limit switch,
Even if there is a failure in the three-way test solenoid valve or the test pilot valve, the main steam isolation valve can be returned to the fully open position without being fully closed during the operation test, improving the reliability of the operation test.

(11) Even if there is a leak in the quick-closing pilot valve, it can be prevented from rapidly closing during the operation test, improving the reliability of the operation test.

(ili) The test pilot valve and the quick-closing pilot valve can be installed separately, and the quick-closing pilot valve can be shared by each main steam isolation valve.

(By sharing one quick-closing pilot valve with each main steam isolation valve, the reliability of the main steam isolation valve is improved and the air circuit is simplified.

〔Effect of the invention〕

As described in detail above, the test device of the present invention can reliably restore the main steam isolation valve to the fully closed state after temporarily operating the main steam isolation valve in the closed direction on a trial basis, thereby preventing any hindrance to the normal operation of nuclear power generation. It has an excellent practical effect that there is no risk of danger.

[Brief explanation of the drawing]

Figures 1 and 2 are explanatory diagrams showing one embodiment of the test device of the present invention. Figure 1 shows the main steam isolation valve in a fully open state, and Figure 2 shows it in a half-closed state. , respectively. FIG. 3 is an explanatory diagram of an embodiment different from the above. Figure 4 is a schematic diagram showing the installation of the main steam isolation valve, Figure 5
Figure 6 is an operational diagram showing a fully open state of a known main steam isolation valve.
The figure shows the fully closed state, and FIG. 7 shows the operation diagram at the time of the same operation test. 1... Main steam isolation valve, 6... Piston, 7.7'.
・・Air cylinder, 21;・22・・Pilot valve for test, 23.24・・3-way solenoid valve for test, 25・
...Air piping, 27...Quick closing air circuit, 28...
・Test air circuit.

Claims (1)

[Claims] 1. In a main steam isolation valve test device for nuclear power generation, which is controlled via pressurized air supplied to an air cylinder that opens and closes the main steam isolation valve, a quick-closing pilot valve, and a test pilot valve. , a port of the air cylinder is provided at a position opposite to the piston of the air cylinder in an intermediate state between when the main steam isolation valve is fully opened and when the main steam isolation valve is fully closed; A test device for a main steam isolation valve for nuclear power generation, characterized in that it is connected to a test cylinder. 2. The testing device for main steam isolation valves for nuclear power generation as set forth in claim 1, wherein the test pilot valves are two in number and connected in parallel. 3. The test pilot valve is connected between the opening/closing air cylinder and the quick closing pilot valve, as claimed in claim 1 or 2. Test equipment for main steam isolation valves for nuclear power generation as described in . 4. The test pilot valve and the quick-closing pilot valve are constructed separately, and the quick-closing pilot valve and the pilot air stop valve are shared by each main steam isolation valve. A test device for a main steam isolation valve for nuclear power generation according to claim 1 or 2.