JPH0666388A - Isolation valve monitor - Google Patents

Abstract

PURPOSE:To provide an isolation valve monitor detecting the state of a valve and a valve control circuit from the valve control circuit current or the distortion quantity of a valve component section to display it or issue an alarm, preventing the inadvertent closing action of the isolation valve at the time of the surveillance test, and having improved reliability. CONSTITUTION:An isolation valve monitor is constituted of current detecting means 33, 34 provided on electric control circuits 28, 32 of solenoid pilot valves 22, 23 of an isolation valve driving mechanism 19, judging units 35, 36 judging whether the outputs are higher or lower than the prescribed values, warning circuits 39, 40 issuing alarm signals when the outputs are higher or lower than the prescribed values, distortion detecting means 48a, 48b provided on an isolation valve 8 and the solenoid pilot valves 22, 23, a judging device 50 detecting the change of the distortion signal and judging the position and abnormality of a valve element, a display device 51 displaying the opening/closing position and abnormal state of the valve from the judgment signal, and warning circuit 63 issuing the alarm signal from the judgment signal when the valve state differs from the valve control.

Description

Detailed Description of the Invention

[0001]

[Field of Industrial Application] The present invention relates to monitoring and diagnosis of the function and soundness of an isolation valve installed in a steam pipe or the like, and particularly to an isolation valve monitor in which the function of a closing operation mechanism can be easily confirmed.

[0002]

2. Description of the Related Art The function of an isolation valve will be described by taking a nuclear power plant as an example. Generally, as shown in the main steam system diagram of FIG. 5, thermal energy generated in a reactor pressure vessel 1 becomes a steam flow. It is supplied to the steam turbine 4 through the main steam pipe 2 through the reactor containment vessel 3, becomes kinetic energy, is converted into electric energy by the generator 6 directly connected to the shaft 5, and is converted from the transmission line 7 into electric power. Power is being transmitted to the demand areas.

A reactor containment vessel 3 is installed in the main steam pipe 2.
Isolation valves 8 and 9 are provided on both sides of the valve. Further, in the vicinity of the turbine 4, a main blocking valve 10 for starting and stopping the turbine 4 and a control valve 11 for adjusting the flow rate of steam to the turbine 4 are provided. Isolation valves 8 and 9 during operation of the reactor
However, in the event of a failure including breakage of the main steam pipe 2 or a failure of the turbine system, radioactive materials from the reactor pressure vessel 1 should not be released to the outside together with steam.
Immediately close the isolation valves 8 and 9.

The two isolation valves 8 and 9 are provided on the inner side and the outer side with the reactor containment vessel 3 interposed therebetween, even if one isolation valve does not close due to a problem, the other isolation valve is provided. This is to prevent leakage of radioactive materials with steam.

Therefore, since the isolation valves 8 and 9 are required to have high reliability, a surveillance test is regularly performed to confirm the closing operation even during operation. If it is closed, the main steam flow rate will fluctuate, and in the worst case, the reactor pressure and neutron flux will fluctuate, and there is a risk of shutting down the reactor. For this reason, these isolation valves 8 and 9 are designed so that they are always closed when the main steam pipe 2 or the turbine 4 fails, and are not closed carelessly in other cases.

That is, the control circuit for closing the isolation valves 8 and 9 has two systems of direct current and alternating current, and an electromagnetic pilot valve for alternating current and direct current and a test electromagnetic pilot valve for alternating current are provided. The isolation valves 8 and 9 are constructed so as not to be closed unless both the electromagnetic pilot valves for AC and AC operate simultaneously. Generally, one reactor has four main steam systems.
Since there is a system, the main steam pipe 2 has four isolation valves 8,
There are 9 units, 4 units each, 8 units in total.

FIG. 6 shows a control system diagram of one isolation valve, in which the main steam 12 from the reactor is a valve case 13 of the isolation valve 8.
The flow path is restricted by the valve body 14 inside. If the valve body 14 is pulled up by the connected valve rod 15 and reaches the upper limit, the main steam 12
And the valve body 14 is at the lower limit, the flow of the main steam 12 stops. A protrusion 16 is provided in the middle of the valve rod 15 and limit switches 17 and 18 are provided at the upper and lower positions to detect the open / close position of the isolation valve 8 from the upper limit and lower limit positions of the valve body 14, respectively.

The valve rod 15 to which the valve body 14 is connected is operated up and down by a valve drive mechanism 19. The valve drive mechanism 19 drives the valve rod 15 by operating gas and a spring, and the cylinder 20. It is composed of a pilot cylinder 21 for operating 20. The pilot cylinder 21 is provided with an AC electromagnetic pilot valve 22, a DC electromagnetic pilot valve 23, and an AC test valve 24.

The AC electromagnetic pilot valve 22 includes an AC power supply 25, a manual opening / closing control switch 26 for the isolation valve 8, an isolation logic 27 for detecting a failure in the main steam pipe 2 and the turbine 4, and automatically isolating the isolation. It is connected to the AC control circuit 28 including wiring inside the panel and cables, and if the manual opening / closing control switch 26 and isolation logic 27 are operated so that the AC electromagnetic pilot valve 22 is not excited, the AC electromagnetic pilot valve 22 will be in the exhaust position. become.

Similarly, in the DC electromagnetic pilot valve 23, the DC power supply 29 has a manual opening / closing control switch 30, and an isolation logic 31 for detecting a failure of the main steam pipe 2 or the turbine 4 and automatically isolating the failure. It is connected to a DC control circuit 32 including wiring and cables, and both the manual opening / closing control switch 30 and the isolation logic 31 are operated so that the DC electromagnetic pilot valve 23 is de-energized. Is the position to exhaust.

Here, when the AC electromagnetic pilot valve 22 and the DC electromagnetic pilot valve 23 are simultaneously unexcited, that is, in the exhaust position, the gas in the cylinder 20 and the pilot cylinder 21 of the valve drive mechanism 19 is exhausted, and the spring force of the cylinder 20 is exhausted. As a result, the valve body 14 descends at high speed and the isolation valve 8 is closed.

During operation of the plant, the manual opening / closing control switches 26 and 30 are closed except at the "isolation valve closed" position, and the isolation logics 27 and 31 are also closed without operation. The pilot valve 22 and the direct-current electromagnetic pilot valve 23 are in a position where the operating gas is supplied in the excited state, the valve rod 15 overcomes the spring of the cylinder 20, and the valve body 14 is held at the upper limit by the operating gas to operate the isolation valve 8. is open.

The AC power supply 25 and the DC power supply 29 are physically independent from other detectors (not shown), control panel, cable route, power supply, etc. so that they do not affect each other. Further, the isolation valves are two valves inside and outside the reactor containment vessel 3, that is, four electromagnetic pilot valves (1
High reliability is ensured by constructing a (2 × 2) logic or a (2/4) logic.

Further, in order to maintain high reliability that the isolation valve 8 is surely closed in an emergency, a periodic operation confirmation test is performed by the automatic isolation logic during the reactor power output operation. That is, first, the isolation logic 31 is automatically operated to check the exhaust operation of the DC electromagnetic pilot valve 23, and then is returned, and then the isolation logic 27 is automatically operated to exhaust the AC electromagnetic pilot valve 22. Check the operation. At this time, both electromagnetic pilot valves 22 and 23 are not in the exhaust position at the same time, so the isolation valve 8 does not close.

[0015]

AC electromagnetic pilot valve
In the AC control circuit 28 of 22 and the DC control circuit 32 of the DC electromagnetic pilot valve 23, the tightening of the connection part or the disconnection in the wiring inside the panel, or the coil of the AC electromagnetic pilot valve 22 or the DC electromagnetic pilot valve 23 is disconnected. In that case, the electromagnetic pilot valve of the control circuit is not excited and is in the exhaust position. Therefore, when an automatic operation test of one isolation logic 27, 31 is performed, both electromagnetic pilot valves 22, 23 are in the unexcited state, The isolation valve 8 will automatically close.

As a result, there is a possibility that the steam flow rate to the turbine 4 may be greatly changed, resulting in output fluctuation and automatic shutdown of the reactor. In particular, in the electric system of the isolation valve 8 installed in the reactor containment vessel 3, the installation environment is bad, and therefore coil breakage, contact failure, and short circuit are likely to occur.

However, the open / close positions of the isolation valves 9 and 8 can be detected by the limit switches 17 and 18, but the electromagnetic pilot valves 22 and 23 have a stroke as long as a device for detecting the air supply / exhaust position of the valve body is provided. Therefore, even if the electromagnetic pilot valves 22 and 23 were de-excited due to the disconnection of the AC control circuit 28 and the DC control circuit 32, the operator in the main control room could not detect this state.

Regarding the isolation valves 8 and 9, the position of the valve element 14 is detected by the limit switches 17 and 18 via the valve rod 15. However, if the valve rod 15 is broken, the valve element 14 is broken.
14 positions cannot be detected. Further, it is more difficult to detect the malfunction of the electromagnetic pilot valves 22 and 23. Therefore, during the opening operation of the isolation valves 8 and 9, the electromagnetic pilot valves 2 and 23 are not operated.
It was requested to develop a measure to monitor the soundness of the valves including 2 and 23 and prevent the isolation valves 8 and 9 from closing carelessly in surveillance tests.

The object of the present invention is to detect the state of the valve and the valve control circuit from the current of the valve control circuit or the amount of distortion of the valve component to display and issue an alarm, and at the time of a surveillance test of the isolation valve. Another object is to provide an isolation valve monitor that prevents inadvertent closing operation and improves the reliability of the system including the isolation valve.

[0020]

A first aspect of the present invention is to provide a current detecting means provided in an electric control circuit of an electromagnetic pilot valve which constitutes a valve drive mechanism of an isolation valve, and an output of the current detecting means is below a prescribed value or It is characterized by comprising a judging device for judging the above, and an alarm circuit for outputting an alarm signal by a signal below or above a specified value from this judging device.

A second aspect of the invention is a strain detecting means provided on a valve such as an isolation valve and an electromagnetic pilot valve, and a discrimination for discriminating a position and abnormality of a valve body by detecting a change of a strain signal from the strain detecting means. A device, a display device for displaying an open / closed position of the valve and an abnormal state from a discrimination signal of the discriminating device, and an alarm circuit for issuing an alarm signal when the discrimination signal of the discriminating device is different from the control for the valve. To do.

[0022]

[Action]

(1) During the isolation valve surveillance test, if a disconnection occurs in one of the control circuits of the two electromagnetic pilot valves that make up the valve drive mechanism that operates the isolation valve, this electromagnetic pilot valve Is the exhaust position. At this time, the current detecting means and the judging device in the control circuit, which are broken, output a low current signal, and the alarm circuit issues an alarm signal when the logical condition with the signal such as the isolation logic is satisfied. With this alarm, the operator stops the surveillance test of the other electromagnetic pilot valve to prevent the isolation valve from closing.

(2) Two electromagnetic pilot valves constituting a valve drive mechanism for operating the isolation valve. When one electromagnetic pilot valve becomes non-excited due to an electrical or mechanical failure, the electromagnetic pilot valve is placed in the exhaust position. Becomes When the strain detecting means detects a change in strain in the valve case and the yoke at the exhaust position of the electromagnetic pilot valve, and the strain measuring device and the discriminating device determine the exhaust position, a valve closing discriminating signal is output to the alarm circuit. The alarm circuit issues an alarm signal when a logical condition with another signal such as isolation logic is satisfied.

In addition, in the discriminating device, an abnormal state is discriminated and displayed on the display device in addition to the opening / closing position of the valve. Therefore, at this time, the operator can easily check the state of the electromagnetic pilot valve in the exhaust position, that another electromagnetic pilot valve is in the air supply position, and that the isolation valve is open on the display device. it can. As a result, the surveillance test for operating the other electromagnetic pilot valve can be immediately stopped, the isolation valve can be prevented from closing, and inadvertent automatic shutdown of the reactor can be avoided.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to the drawings. It should be noted that the same components as those in the above-described conventional technique are designated by the same reference numerals and detailed description thereof will be omitted. The isolation valve system configuration diagram of FIG. 1 is the first invention, and only one system is illustrated. The flow path of the main steam 12 from the nuclear reactor is restricted by the valve body 14 in the valve case 13 of the isolation valve 8. The valve body 14 is a connected valve rod
When the valve 15 is pulled up by 15 to reach the upper limit, the isolation valve 8 is fully opened and the main steam 12 flows, and when the valve body 14 is at the lower limit, the main steam 12 is fully closed and the main steam 12 is stopped.

The valve rod 15 to which the valve element 14 is connected is operated up and down by a valve drive mechanism 19. The valve drive mechanism 19 drives the valve rod 15 by operating gas and a spring.
20 and pilot cylinder 21 for operating this cylinder 20
The pilot cylinder 21 is provided with an operating AC electromagnetic pilot valve 22, a DC electromagnetic pilot valve 23, and an AC test valve 24.

The AC electromagnetic pilot valve 22 is an isolation logic 27 for automatically detecting and isolating the failure of the manual opening / closing control switch 26 and the main steam piping 2 and the turbine 4 in the AC power supply 25.
a, an in-board wiring, and an AC control circuit 28 including a cable, and a manual opening / closing control switch 26 and an isolation logic.
By opening 27a and operating the AC electromagnetic pilot valve 22 so that it is not excited, the AC electromagnetic pilot valve 22 is at the exhaust position.

Similarly, in the DC electromagnetic pilot valve 23, the DC power source 29 has a manual opening / closing control switch 30, and an isolation logic 31a for automatically detecting and isolating the failure of the main steam pipe 2 and the turbine 4, and the inside of the panel. It is connected to a DC control circuit 32 including wiring and cables, and if the manual opening / closing control switch 30 or the isolation logic 31a operates so as to de-energize the DC electromagnetic pilot valve 23, the DC electromagnetic pilot valve 23
Is the position for exhausting the operating gas.

Further, clip type current detectors 33 and 34, which are current detecting means, are attached to both control circuits 28 and 32 of the AC electromagnetic pilot valve 22 and the DC electromagnetic pilot valve 23, respectively.
The currents detected by the current detectors 33, 34 are read by the determiners 35, 36. The determiners 35 and 36 output the low current signals 37a and 38a or the high current signals 37b and 38b, respectively, when detecting an abnormality in which the currents flowing through the control circuits 28 and 32 are different from the normal values.

The current low signal 37a, 38a and the current high signal 37b, 38b are separately introduced to output an alarm signal. The current low signal 37a and the current high signal 37b, or the current low signal 38a.
And an OR logic consisting of a high current signal 38b, and each OR logic and isolation logics 27b and 31b for detecting and automatically isolating a failure of the main steam pipe 2 or turbine 4, respectively. It is configured by providing circuits 39 and 40.

Next, the operation of the above configuration will be described. The manual open / close control switches 26, 30 are closed because they are not in the "isolation valve closed" position, and the isolation logic 27a, 27b, 31a, 31b.
Both control circuits 28, 32 including the coils of the AC electromagnetic pilot valve 22 and the DC electromagnetic pilot valve 23 in the valve drive mechanism 19 that controls the isolation valve 8 in the closed state without operating
If there is a disconnection or contact failure in the
The current value detected by 33, 34 is zero or smaller than the normal value. Therefore, the determiners 35, 36 judge this to be abnormal and output the low current signals 37a, 38a to the monitoring circuits 39, 40.

This problem is caused by the AC electromagnetic pilot valve 22.
Side AC control circuit 28, AC electromagnetic pilot valve 22
Becomes the exhaust position, and the monitoring circuit 39 outputs the alarm signal 39a from the low current signal 37a and the isolation logic 27b which is output when there is no failure other than the isolation valve 8. This alarm signal 39
"a" is notified to the operator or the like by turning on an indicator lamp by a warning device (not shown) and by a buzzer.

When an overcurrent flows due to a short circuit or the like in the AC control circuit 28, an alarm signal 39 is generated by the high current signal 37b.
Although a is output, the AC electromagnetic pilot valve 22 is also in the exhaust position at this time. In addition, the DC solenoid pilot valve 23
In the case of a failure in the DC control circuit 32 on the side, an alarm signal 40a is output from the monitoring circuit 40.

Therefore, according to the first aspect of the present invention, by measuring the current of the control circuits 28, 32 to which the electromagnetic pilot valves 22, 23 of the isolation valve drive mechanism 19 are connected, Disconnection including solenoid pilot valves 22 and 23
It is possible to quickly detect an abnormal state such as a contact failure or a short circuit.

During the surveillance test, if one electromagnetic pilot valve is in the exhaust position without excitation due to a control circuit failure, the operator is immediately alerted to this condition by avoiding the test of the other electromagnetic pilot valve. Therefore, the careless closing operation of the isolation valve 8 during the test can be prevented, and the soundness of the reactor can be maintained.

Further, the current detectors 33 and 34 are devices such as clip type ammeters which can be used without adding any parts, cables or processing to the existing control circuits 28 and 32, Without reducing the reliability of the control circuits 28 and 32,
It can be easily adopted in conventional plants.

The monitor configuration diagram of FIG. 2 shows an embodiment of the second invention, and one electromagnetic pilot valve is taken as an example. The AC electromagnetic pilot valve 22 has a valve body (not shown) housed in the valve case 41, is integrally connected to a valve rod 43 that protrudes through the valve lid 42, and further has an iron core 44 integrated with the valve rod 43. Is operated against the spring force of the spring 46 by energizing the electromagnetic coil 45, the valve is opened and closed. Also valve rod 43
Is reinforced and supported by a yoke 47, and its vertical movement is guided.

On the bottom of the valve case 41 and the yoke 47,
The strain gauges 48a and 48b, which are strain detecting means, are attached with an adhesive or the like. Each strain gauge 48a, 48b is provided with a strain measuring device 49a, 49b for detecting the voltage change of the strain signal from the strain gauge 48a, 48b, respectively, and the electromagnetic pilot valve 22 is supplied from the outputs of these two strain measuring devices 49a, 49b. Air / exhaust position, discriminating device 50 for discriminating abnormality, and the air supply / exhaust position or the output signal from the discriminating device 50,
A display device 51 for displaying an abnormality is connected.

The characteristic curve diagram of FIG. 3 exemplifies the change in strain of the AC electromagnetic pilot valve 22 which operates normally in the above-mentioned configuration with respect to the valve opening direction. FIG. 3A shows the bottom of the valve case 41. Further, FIG. 3B shows a state where strain is generated on the outer side portion of the yoke 47.

That is, the strain signal of the strain gauge 48a at the bottom of the valve case 41, as shown by the curve 66 in FIG. 3 (a), has a tensile force acting on the bottom of the valve case 41 when the electromagnetic pilot valve 22 is in the exhaust position. Then, in response to this strain, the strain measuring device 49a detects a voltage change on the tension side (+). Further, in the case other than the exhaust state, since the stress acting is small, no strain is generated, and therefore the output signal of the strain measuring device 49a becomes zero.

On the other hand, a strain gauge outside the yoke 47
As shown by a curve 67 in FIG. 3 (b), the strain signal of 48b causes the valve element (not shown) to be strongly crimped to the valve push (not shown) of the valve case 41 via the valve rod 43 in the exhaust position. Compressive force acts on the outer surface of the yoke 47.

On the other hand, at the air supply position, the tip end of the valve rod 43 is strongly pressed against the back seat (not shown), so that a tensile force acts, and in each case, a strain is generated as a voltage change corresponding to the direction of strain generation. It is detected by the measuring device 49b. Therefore, the strain signals from the strain gauges 48a and 48b are measured by the strain measuring devices 49a and 49b, respectively,
The output signal level is adjusted and then input to the discrimination device 50.

In the discriminating device 50, the magnitude of the strain signals from the strain measuring devices 49a and 49b and the degree of the strain, that is, the location of the strain signal, the positive / negative direction of the signal, the signal waveform, the peak value, etc. The opening degree and operating state of the AC electromagnetic pilot valve 22 are determined according to the categories (a) to (e).

(A) When the signal from the strain gauge 48b of the yoke 47 and the signal from the strain gauge 48a of the valve case 41 are negative and the signal from the strain gauge 48a of the valve case 41 is above the specified value, Exhausted state. (B) When the signals from the strain gauge 48b of the yoke 47 and the strain gauge 48a of the valve case 41 are both below the specified value, the air supply state is established.

(C) The strain gauge 48b of the yoke 47,
When the signals from the strain gauge 48a of the valve case 41 are both below the specified value, the state is the intermediate opening. (D) When the signal from the strain gauge 48b of the yoke 47 is other than negative and the signal from the strain gauge 48a of the valve case 41 is equal to or more than the specified value, the valve body (not shown) of the valve rod 43 is separated. Shows the state.

(E) The signal from the strain gauge 48b of the yoke 47 is negative and the strain gauge 48 of the valve case 41 is
If the signal from "a" is zero, it indicates that the valve rod 43 has been stuck on the way. As described above, in the discrimination device 50, (a) to
The state of (c) is identified, and the display device 51 displays the exhaust gas, the air supply, and the intermediate opening degree of the AC electromagnetic pilot valve 22, respectively. When an abnormal state such as (d) or (e) occurs, an abnormal signal is output to the display device 51, the indicator lamp is turned on, and a buzzer or the like is sounded to notify the operator.

In the second aspect of the invention described above, the open / closed position of the valve and the normal and abnormal states can be detected from the outside of the valve, and the small strain gauges 48a and 48b, which are strain detecting means, are attached to the outer side of the valve with an adhesive. It can be applied to an existing plant very easily because it is just pasted. Although the AC electromagnetic pilot valve 22 is used in the above embodiment, the invention is not limited to this, and the DC electromagnetic pilot valve 23 and the isolation valve 8 of FIG.
It is needless to say that the same action and effect can be obtained by adopting various valves such as.

The isolation valve control system diagram of FIG. 4 shows another embodiment of the second invention, which is applied to a surveillance test for the isolation valve 8 and the electromagnetic pilot valves 22 and 23. A valve drive mechanism 19 is attached to the isolation valve 8 via a valve rod 15.
This valve drive mechanism 19 is connected with an AC electromagnetic pilot valve 22 connected to an AC power supply 25, a DC electromagnetic pilot valve 23 connected to a DC power supply 29, and an AC test valve 24. And is operated via the operating gas.

The AC power source 25 has a manual opening / closing control switch.
26a, an isolation logic 27a that automatically detects and isolates a failure of the main steam pipe 2 or turbine 4, and an AC control circuit 28 that connects the coil of the AC electromagnetic pilot valve 22 to the DC power supply 29. Switch 30a and isolation logic 31a
A coil of the DC electromagnetic pilot valve 23 is connected to form a DC control circuit 32.

Further, the valve case 41 of the AC electromagnetic pilot valve 22
The strain gauges 48a and 48b, which are strain detecting means, are attached to the yoke 47, and the strain measuring devices 49a and 49b, the discriminating device 50, and the display device 51 are connected. The strain gauges 52a, 52b and strain gauges are also provided on the DC electromagnetic pilot valve 23.
53a, 53b, the discriminating device 54, and the display device 55 are connected.

Further, strain gauges 56a and 56b are attached to the valve case 13 of the isolation valve 8 to provide strain measuring devices 57a and 57b.
The discriminating device 58 and the display device 59 are connected and provided. The discrimination devices 50, 54, 58 are the strain gauges.
The valve closing determination signals 60, 61, 62 are output from the distortion signals of 48a, 48b, 52a, 52b, 56a, 56b.

Separately, a monitoring circuit 63 for issuing an alarm signal 63a according to the AND logic condition of the valve closing discrimination signal 60 of the discrimination device 50, the manual opening / closing control switch 26b and the isolation logic 27b, and the discrimination device 54.
Monitoring signal 64 for outputting an alarm signal 64a according to the AND logic condition of the valve closing discrimination signal 61 of the manual opening / closing control switch 30b and the isolation logic 31b, the valve closing discrimination signal 62 of the discrimination device 58, and the manual opening / closing control switch 26c. AND of logic 27c and AND of manual opening / closing control switch 30c and isolation logic 31c
The monitoring circuit 65 outputs an alarm signal 65a under an AND logic condition with a logical OR logic.

Next, the operation of the above configuration will be described. When the isolation valve 8 is opened in the operating state, the AC electromagnetic pilot valve 22 and the DC electromagnetic pilot valve 23 are excited and the manual opening / closing control switches 26a, 26b, 26c, 30a, 30
b, 30c and isolation logic 27a, 27b, 27c, 31a, 31b,
Although both 31c are closed, the valve closing discrimination signals 60, 61, 62 from the discrimination devices 50, 54, 58 are not output, and therefore the alarm signal
63a, 64a and 65a are not output.

The display devices 51, 55 and 59 include the AC electromagnetic pilot valve 22 and the DC electromagnetic pilot valve 23 and the isolation valve 8 which are based on the strain signals of the strain gauges 48a, 48b, 52a, 52b, 57a and 57b. The air supply / exhaust positions are displayed on the discrimination devices 50, 54, and 58 by the above (a) to (c).

Here, in the AC control circuit 28, the manual opening / closing control switch 26a is closed in a state other than "isolation valve closed", and there is no failure in the main steam pipe 2 or the turbine 4, and the isolation logic 27
Although a is also in the closed state, if the AC power supply 25 is lost, or if the control circuit 28 including the coil of the AC electromagnetic pilot valve 22, the wiring in the panel, and the cable has a poor contact or disconnection, the AC electromagnetic pilot valve 22 will be closed. Since there is no excitation, the AC electromagnetic pilot valve 22 is in the exhaust position.

When the AC electromagnetic pilot valve 22 is in the exhaust position, the voltage change detection signals of the strain measuring devices 49a and 49b due to the strain signals from the strain gauges 48a and 48b are input to the discriminating device 50 and the (a) above is applied. The exhaust state of the AC electromagnetic pilot valve 22 is determined, and the exhaust position is displayed on the display device 51.

Further, since the AC electromagnetic pilot valve 22 is in the exhaust position, the discriminator 50 outputs the valve closing discrimination signal 60 to the alarm circuit 63, and the alarm circuit 63 outputs the alarm signal 63a. As a result, when the operator conducts a surveillance test by the automatic operation of the isolation logic 31a of the isolation valve 8 in this state, if the direct current electromagnetic pilot valve 23 is put into the exhaust state, both the electromagnetic valves together with the alternating current electromagnetic pilot valve 22 are operated. It can be seen that the pilot valves 22 and 23 are in the exhaust state at the same time and the isolation valve 8 closes.

Therefore, it is possible to immediately stop the surveillance test, investigate defects in the AC control circuit 28, and arrange repairs, thereby avoiding troubles in the reactor and the main steam system. Further, even when a failure occurs in the DC control circuit 32, as in the case of the AC control circuit 28, the discriminating device
54, the display device 55 and the alarm circuit 64 are activated to activate the alarm signal 64.
a is output.

If the manual opening / closing control switches 26a, 26
c, 30a, 30c are closed in a state other than "isolation valve closed", and isolation logics 27a, 27c, 31a, 31c are also closed,
When the surveillance test is performed without noticing the failure of any one of the control circuits 28 and 32, the isolation valve 8 is closed, and at this time, the valve closing discrimination signal 62 from the discrimination device 58 by the above (c) or (a). This activates the alarm circuit 65 to output an alarm signal 65a.

According to the other embodiments, in the AC control circuit 28 of the AC electromagnetic pilot valve 22 and the DC control circuit 32 of the DC electromagnetic pilot valve 23, the power is lost, the coils of the electromagnetic pilot valves 22 and 23, the board Failure of electrical circuits such as contact failure and disconnection including internal wiring and cables, and valve rods 15, 43 and valve body 14 of isolation valve 8 and solenoid pilot valves 22, 23
Even when there is an abnormality due to separation of the valve stems or mechanical failure of the stack of the valve rods 15, 43, etc., the valve fully open / fully closed positions according to the above (a) to (c) and (d) and (e) The abnormality is discriminated by the discriminating devices 50, 54 and 58 and displayed on the display devices 51, 55 and 59, respectively, and the discriminating devices 50, 54 and 58 are appropriately discriminated.
It is possible to obtain a discrimination signal from 54 and 58 and issue an alarm thereby to notify the operator in the main control room.

According to this and other embodiments, the strain gauge 48 is provided on the outer surface of the isolation valve 8 and the electromagnetic pilot valves 22 and 23.
a, 48b, 52a, 52b, 57a, 57b can be simply attached to the control circuit without changing the structure of the isolation valve 8 or the electromagnetic pilot valves 22, 23 having a short operation stroke.
It is possible to detect the valve opening state and abnormality without adding anything to 28 and 31. Further, by issuing an alarm for this abnormality, the isolation valve 8 can be prevented from being closed due to an inadvertent surveillance test, and an abnormal state due to a mechanical failure of the valve can be detected and an alarm can be issued, so that the operator can quickly operate. You can drive treatment.

[0062]

As described above, according to the present invention, in the first invention,
It is possible to detect the current of the control circuit of the electromagnetic pilot valve that controls the isolation valve, diagnose the abnormality of the control circuit, notify this, and avoid the inadvertent closing of the isolation valve in the surveillance test. is there. Further, the present invention can be easily added without adding a cable from the site or modifying the isolation valve.

Further, in the second invention, like the first invention, the device can be easily adopted, and the cause in the control circuit of the electromagnetic pilot valve is included from a plurality of distortion signals in the isolation valve including the electromagnetic pilot valve. It is possible to detect abnormalities in the valve exhaust / air supply position and the valve disc to avoid an unexpected nuclear shutdown due to the unexpected isolation valve closing operation during a surveillance test, and to facilitate a quick repair system by early detection of a valve abnormality. Therefore, the reactor shutdown period including the periodic inspection is shortened, and the operation rate of the nuclear power plant is substantially improved.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an isolation valve system showing an embodiment of a first invention according to the present invention.

FIG. 2 is a monitor configuration diagram showing an embodiment of a second invention according to the present invention.

FIG. 3 is a characteristic curve diagram according to a second aspect of the present invention, in which FIG. 3 (a) shows distortion characteristics at the bottom of the valve case and FIG. 3 (b) shows distortion characteristics at the yoke.

FIG. 4 is a configuration diagram of an isolation valve system showing another embodiment according to the second invention.

FIG. 5 is a schematic diagram of a main steam system of a conventional boiling water nuclear power plant.

FIG. 6 is a conventional isolation valve control system diagram of one system.

[Explanation of symbols]

8, 9 ... Isolation valve, 12 ... Main steam, 13, 41 ... Valve case, 14 ...
Valve body, 15, 43 ... Valve rod, 19 ... Valve drive mechanism, 20 ... Cylinder,
21 ... Pilot cylinder, 22 ... AC solenoid pilot valve,
23 ... DC electromagnetic pilot valve, 24 ... AC test valve, 25 ... AC power supply, 26, 26a to 26c, 30, 30a to 30c ... Manual opening / closing control switch, 27, 27a to 27c, 31, 31a to 31c ... Isolation logic, 28 ... AC control circuit, 29 ... DC power supply, 32 ... DC control circuit, 33, 34 ... Current detector, 35, 36 ... Judgment device, 37a, 38a
... low current signal, 37b, 38b ... high current signal, 39, 40, 63,
64, 65 ... Monitoring circuit, 39a, 40a, 63a, 64a, 65a ... Alarm signal, 44 ... Iron core, 45 ... Electromagnetic coil, 46 ... Spring,
47 ... York, 48a, 48b, 52a, 52b, 56a, 56b ... Strain gauge, 49a, 49b, 53a, 53b, 57a, 57b
... Strain measuring device, 50, 54, 58 ... Discriminating device, 51, 55, 59 ... Display device, 60, 61, 62 ... Valve closing discrimination signal.

Claims (2)

[Claims] 1. A current detecting means provided in an electric control circuit of an electromagnetic pilot valve constituting a valve driving mechanism of an isolation valve, a judging device for judging whether the output of the current detecting means is below or above a specified value, and this judgment. An isolation valve monitor comprising an alarm circuit that outputs an alarm signal when the signal is below or above a specified value from the container. 2. A strain detecting means provided on a valve such as an isolation valve and an electromagnetic pilot valve, a discriminating device for discriminating a position and abnormality of a valve disc by detecting a change in a strain signal from the strain detecting means, It is characterized by comprising a display device for displaying the open / closed position of the valve and an abnormal state from the discrimination signal of the discrimination device, and an alarm circuit for issuing an alarm signal in a state different from the control of the valve by the discrimination signal of the discrimination device. Isolation valve monitor.