JPH0820544B2 - Scram pilot valve operation confirmation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial field of application) The present invention relates to a scram pilot valve operation confirmation device for confirming the soundness of the operation of a scrum pilot valve that operates during a nuclear reactor emergency shutdown. .

(Prior Art) Reactor emergency stop devices in nuclear power plants are required to have high reliability so that they can function as designed when an emergency stop is required. Further, it has a sufficient circuit redundancy and a complicated circuit configuration so as to be able to cope with a failure of a device configured to prevent an adverse effect of an emergency stop due to a malfunction.

In particular, the reliability of the operation of the scrum pilot valve, which serves as an operating valve for the emergency insertion of control rods during a nuclear reactor emergency shutdown, is an important item that affects the function of the nuclear reactor emergency shutdown device. In order to maintain and confirm its reliability, periodical operation tests are obligatory not only during periodic inspections of the nuclear reactor but also during operation.

However, conducting a complete operational test of the reactor emergency shutdown device, such as inserting all control rods during the continuous operation of the reactor, may lead to the problem of thermal shock to the reactor and a decrease in the operating rate of the power plant. Since it is invited, it cannot be implemented in reality. Therefore, the operating circuit of the device is configured so that the test calibration can be performed by separating each small circuit.
In other words, conventionally, only the logic circuit corresponding to each scrum signal composed of the electric circuit of the reactor emergency stop device was manually selected, and the operation test was performed by artificially tripping to confirm only the soundness of each logic circuit. Was.

Here, the configuration of a conventional reactor emergency stop device including a scrum pilot valve will be described with reference to FIG.

A reactor core 2 is formed inside the reactor pressure vessel 1, and light water 3 is filled therein as a coolant. A large number of combustion assemblies (not shown) are vertically arranged in the core 2.
The reactor power is controlled by inserting or withdrawing the control rods 4A to 4N into the gap of the fuel assembly. A reactor with an output of 1 million Kw is loaded with about 200 control rods, and each control rod is directly connected to a hydraulic control rod drive mechanism (hereinafter referred to as CRD) 5A to 5N to drive the control rods. The insertion position of the core into the core is adjusted. Furthermore, each CRD is equipped with a water pressure control unit (hereinafter referred to as HCU) 19A for controlling the drive water supplied to the control rod drive mechanism. The HCU is constantly supplied with various types of high-pressure water adjusted by the control rod drive water pressure system, and in response to the operation signal from the central control room, the HC
U supplies the required drive water to the CRD and controls the reactor. The control rod drive mechanism (CRD) 5A to 5N adopts a hydraulic drive piston system. An extraction pipe 6A and an insertion pipe 7A are connected to the upper surface side and the lower surface side of the inserted piston, respectively. These withdrawal pipe 6A and insertion pipe 7A
The control rods 4A to 4N are inserted into or pulled out of the fuel assemblies (not shown) of four bodies by supplying high-pressure driving water to the pistons, and the control rods 4A to 4N are pulled out from the fuel assemblies. The output control during normal operation is being performed.

In addition, in the event of a reactor failure, the HCU1 that determines the flow path of high-pressure drive water based on the reactor scrum signal from the reactor protection system.
The 9A scrum outlet valve 8A and the scrum inlet valve 9A are opened. Then, the high-pressure drive water stored in the accumulator (not shown) is supplied to the CRD piston lower surface side through the drive water insertion pipe 11A, while the return water on the piston upper surface side is
It is discharged through the driving water drainage pipe 10A.

Here, the valve opening control units of the scrum outlet valve 8A and the scrum inlet valve 9A are connected to the scrum pilot valve 13A and the scrum pilot valve 14A via the scrum valve air pipe 12A. During normal operation of the nuclear reactor, the scram outlet valve 8A and the scrum inlet valve 9A are closed by the air pressure of the working air supplied from the air header 17A via the scrum pilot valves 13A and 14A. At this time, CRD is HCU19
It is controlled by switching the flow direction of the driving water by the 4-way control valve in A.

Three-way solenoid valves 15A and 16A are attached to the scrum pilot valves 13A and 14A, respectively. The three-way solenoid valves 15A and 16A are energized during normal reactor operation, and the air header
The working air from 17A is supplied to the scrum outlet valve 8A and the scrum inlet valve 9A via the scrum valve air pipe 12A, and these valves are closed. Here, three-way solenoid valves 15A, 16A
Are normally excited by the output signals of the scram circuit I 20 and the scrum circuit II 21 of the nuclear reactor emergency stop system. When an abnormality occurs in the reactor, the scrum circuit I 20
And the output signal of the scrum circuit II 21 is cut off, the scrum pilot valves 13A and 14A are switched to non-excited state, and the air in the scrum valve air pipe 12A is exhausted through the exhaust pipe 18A. Then, the scram outlet valve 8A and the scrum inlet valve 9A are instantly opened to drive the high-pressure drive water into the drive water insertion pipe.
Feed it to CRD via 11A and insert the control rod into the core rapidly. The driving water pushed out from the CRD passes through the extraction pipe 6A,
Further, the water is discharged through the driving water discharge pipe 10A.

Next, the configuration of the reactor scrum circuit for operating the scrum pilot valves 13A and 14A will be described with reference to FIG.

The nuclear reactor scrum circuit is composed of two channels of a scrum circuit I 20 and a scrum circuit II 21. Each channel incorporates logic circuits 23-25, 36-38 for detecting reactor anomalies such as high reactor pressure, low reactor water level, high neutron flux, etc. and transmitting a reactor scrum signal. There is. The contactor 26-28,3 is connected to the logic circuit of each channel.
9 to 41 and contacts 26A to 28A and 39A to 41A are provided in series.

If the logic circuits 23 to 25 of the scrum circuit I are healthy, the contactors 26 to 28 are activated and the contacts 26A to 28A are closed. In addition, each channel is provided with the same number of simple rod scrum switches 29A to 29N as the control rods, and by selecting these switches, a single insertion test of each control rod is possible. Normally, a signal flows to the power supply 31 while exciting the solenoid valve 15A through a closed circuit from the power supply 30 through the contacts 26A to 28A to the simple rod scrum switch 29A.

Similarly, the same applies to the scrum circuit II. If no abnormality is detected in each logic circuit, the signal is
It flows from 43 through the contacts 39A to 41A to the power source 44 while exciting the solenoid valve 16A.

When the solenoid valves 15A and 16A are excited, the scrum pilot valves 13A and 14A supply the pressure air from the air header 17A to the scram output valve 8A and the scrum inlet valve 9A via the scram valve air pipe 12A, and the pressure causes 2 Two valves are closed.

The logic circuits 25 and 38 are logic circuits for scramming by a manual operation of an operator.

When an abnormality of the reactor is detected at the same time in the scrum circuit I 20 and the scrum circuit II 21, the contactor of each channel is restored and the contacts are opened. As a result, the solenoid valves 15A and 16A are demagnetized, the scrum pilot valves 13A and 14A are switched, the compressed air in the scrum valve air pipe 12A is discharged from the exhaust pipe 18A, and at the same time the scrum outlet valve 8A and the scrum inlet valve 9A are opened. Valve and then emergency insert control rods 4A-4N into the core. The safety of the reactor is ensured by this reliable scrum operation.

(Problems to be Solved by the Invention) In the nuclear reactor emergency shutdown device as described above, in order to maintain and guarantee the function of operating reliably when an abnormality occurs in the reactor, an operation test is regularly performed even during the operation of the reactor. It has been implemented.

However, in the conventional operation test, each logic circuit in the scrum circuit is artificially tripped to confirm whether or not the contactor is opened. In this case, the soundness of the circuit was confirmed, but it could not be confirmed that the switching operation of the scrum pilot valves 13A, 14A was reliably executed.
Therefore, it was necessary to closely check the operation of all scrum pilot valves during the periodic inspections performed with the reactor shut down. In this confirmation work, it is reported that the malfunction of the scrum pilot valve is discovered for the first time. Note that this confirmation work generally requires a large number of workers over a long period of time. On the other hand, in response to increasing social demands for improving the operating rate of nuclear power plants, the continuous operation of the reactor for a long time and the shortening of the reactor shutdown period for periodic inspection are being considered. Therefore, a means for confirming the reliable operation of the scrum pilot valve even during the operation of the reactor has been desired. However, since the scrum pilot valve is generally a valve having a small diameter, it is difficult to provide a limit switch or the like that mechanically detects the opening degree.

The present invention has been devised to solve the above problems, and further expands the function confirmation range in the operation test of the reactor emergency shutdown device from the operation confirmation of the conventional electrical logic circuit, The purpose is to improve the reliability of the reactor emergency shutdown device by enabling confirmation of mechanical operation.

Another object of the present invention is to detect a failure of a logic circuit for detecting an abnormality of a nuclear reactor or a defective part of a scrum pilot valve at an early stage, shorten the investigation and repair time, shorten the periodic inspection period, and substantially reduce the nuclear power. It is to improve the operating rate of the power plant.

[Structure of Invention]

(Means for Solving the Problems) A device for confirming the operation of a scrum pilot valve according to the present invention is a strain gauge which is attached to the scrum pilot valve and detects strain generated as the scram pilot valve opens and closes as a strain signal. And a signal switching device that switches the strain signal transmitted from the strain gauge for each scrum pilot valve, a strain measuring device that measures the strain signal as a voltage change, and the operating state of the scrum pilot valve is determined by the signal waveform of the voltage change. Discriminating device, a valve discriminating device that discriminates the operating state as operating data for each scrum pilot valve, and a valve that inputs a signal for sequentially selecting the scrum pilot valve to be subjected to the operation test to the signal switching device and the valve discriminating device. A selection device, a storage device for updating and storing operation data of each scrum pilot valve, and a storage device The display device that displays the operation data of each scrum pilot valve output from the operator to the operator and the evaluation device that evaluates the soundness of the operation of each scrum pilot valve based on the operation data output from the storage device The main point is to confirm the soundness of the operation of the scrum pilot valve during an emergency shutdown of the reactor.

(Operation) According to the operation confirmation device of the scrum pilot valve of the present invention, the strain gauge electrically detects the strain generated due to the change in the opening direction of the scrum pilot valve, and the operation of the scrum pilot valve is detected by the signal waveform. The state is determined. That is, during the operation test, the scrum circuit is tripped on a trial basis, and the distortion that occurs in the valve box, the yoke, etc. is deducted when the electromagnetic coil of the scrum pilot valve is demagnetized and when it is excited. By electrically detecting the situation, its operating state can also be determined. That is, the electrical integrity of the scrum circuit and the mechanical integrity of the scrum pilot valve can be confirmed at the same time.

Further, the operating state data individualized for each scrum pilot valve by the valve identification device is stored in the storage device,
Since it is clearly indicated to the operator by the display device, the failure point can be instantly identified, the maintenance and management of the reactor emergency stop device can be facilitated, and the reliability of the scram operation can be improved.

Furthermore, even during reactor operation, the operation of the scram pilot valve can be confirmed by the valve selection device alone, and the operation of the evaluation device that compares the operation data with the operation data stored in the storage device in advance. Thus, the soundness of the operating condition of the scrum pilot valve is instantly evaluated. If the soundness is significantly reduced, the operator is automatically notified by an alarm device. In this way, the soundness of the operation of the scrum pilot valve, which plays an important role in the reactor emergency shutdown device, is confirmed.

(Embodiment) Next, an embodiment of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a block diagram showing the configuration of an operation confirmation device for a scrum pilot valve according to the present invention.

The number of control rods for a 1 million KWe class power generation reactor reaches about 200, and the reactor emergency stop device that inserts these control rods into the reactor core has a complicated structure. Scrum pilot valve 50 (second
2) are provided for each control rod. In the scrum pilot valve 50, a valve body (not shown) is housed in a valve box 51, the valve body is integrally connected to a valve rod 53 protruding through the valve lid 52, and an iron core 55 integrated with the valve rod is electromagnetically coupled. When the coil 56 is energized, the valve body is opened and closed by controlling the operation against the spring force of the spring 57. The valve rod 53 is
It is reinforced by the yoke 54, and its operation is guided (second
See figure).

Bottom of valve box 51 and yoke of scrum pilot valve 50
Strain gauges 71A and 72A are attached to 54, respectively, and the strain gauges 71A and 72A detect the strain generated with the change in the opening direction of the scrum pilot valve. The output signals of the strain gauges 71A and 72A are input to the signal switching device 74 of the scrum pilot valve operation confirmation device 73.

On the other hand, the scram pilot valve operation confirmation device 73 accommodates a valve selection device 79, and the valve selection device 79 is connected to the signal switching device 74 and the valve identification device 78. A selection signal from the valve selection device 79 is input to the signal switching device 74 and the valve identification device 78 to sequentially select the scrum pilot valve to be the target of the operation test.

In the signal switching device 74, the valve box of all scrum pilot valves
51 Strain gauges 71A, 72A attached to the bottom and yoke 54;
71B, 72B; ......; The strain signals from 71N, 72N are combined into one set for each scrum pilot valve, and are sequentially switched to high-speed cyclic.

The strain signals from the strain gauges selected by the signal switching device 74 are input to the strain measuring devices 75 and 76, respectively, and the output signal level is adjusted. The output signals of the strain measuring devices 75 and 76 are input to the discriminating device 77, where the combinations of polarities and level values of the two strain signals transmitted from the bottom of the valve box of each scrum pilot valve and the yoke are compared and calculated. Determine the opening direction of the pilot valve.

FIG. 3 exemplifies a change in strain with respect to the position of the valve in the opening direction in the scrum pilot valve which operates normally. (A) and (b) are a yoke 54 and a valve box, respectively.
The state of occurrence of strain at the bottom of 51 is shown. That is, the strain signal of the strain gauge 72A attached to the yoke 54 is generated by the valve element (not shown) through the valve rod 53 when the scrum pilot valve is in the exhaust state as shown in FIG. 3 (a). The yoke 54 is strongly pressed against the presser foot (not shown).
Compressive force acts on the outer surface of. On the contrary, in the air supply state, the tip end of the valve rod 53 is strongly pressed against the back seat (not shown), so that a tensile force acts. In each case, the strain measuring device 76 detects a voltage change corresponding to the strain generation direction.

On the other hand, a strain gauge 71 attached to the bottom of the valve box 51.
As shown in Fig. 3 (b), the strain signal of A has a tensile force acting on the bottom of the valve box 51 when the scrum pilot valve is in the exhaust state, and the tension (+) side voltage change corresponding to this strain. Is detected by the strain measuring device 75 as In the case where the valve box is not in the exhaust state, the stress acting on the valve box is small, so that no strain occurs. Therefore, the output signal of the strain measuring device 75 becomes zero.

In this way, the strain signals from the strain gauges 71A, 72A attached to the scrum pilot valve are respectively measured by the strain measuring device 75,
It is measured by 76 and the output signal level thereof is adjusted and then input to the discriminating device 77. In the discriminating device 77, the magnitude of the distortion signal and the degree of distortion, that is, the characteristics of the output voltage such as positive / negative, the signal waveform, and the peak value, are used to determine the opening direction state of the scrum pilot valve according to the following categories (a) to (e) And determine the operating state.

(A) When the signal from the strain gauge 72A of the yoke 54 is negative and the signal from the strain gauge 71A of the valve box 51 is equal to or more than the specified value, the exhaust state is established.

(B) When the signals from the strain gauge 72A of the yoke 54 and the strain gauge 71A of the valve box 51 are both below the specified value, the air supply state is established.

(C) When both the signals from the strain gauge 72A of the yoke 54 and the strain gauge 71A of the valve box 51 are equal to or less than the specified values, the state is the intermediate opening state.

(D) When the signal from the strain gauge 72A of the yoke 54 is not negative and the signal from the strain gauge 71A of the valve box 51 is equal to or more than the specified value, the valve rod 53 and the valve disc (not shown)
Shows the separated state.

(E) If the signal from the strain gauge 72A of the yoke 45 is negative and the signal from the strain gauge 71A of the valve box 51 is zero, it means that the valve rod 53 has stuck on the way.

These operating state signals are input to the valve identification device 78,
It is input to the storage device 80 after being combined with the signal of the valve selection device 79 to identify which valve the operation data is. The input operation data of all the scrum pilot valves are stored until the next operation test and updated every cycle of the operation test.

The stored operation data is input to the transmission device 82 and the evaluation device 81. In the transmission device 82, the operation data of all scrum pilot valves are received by the reception device 83 by the function of the multiplex transmission function.
Transmit to. Here, the serial signal is converted into a parallel signal, and the operating state of each scrum pilot valve is displayed on the display device 84 in accordance with the states (a) to (c) in the discrimination device 77 described above, respectively. Qi, turn on the indicator light of the intermediate opening.

On the other hand, the scram signal 87 of the scram circuit I 20 and the scrum signal of the scrum circuit II 21 of the reactor emergency stop device
When 88 is input to the starter 86, the starter 86 is a half scrum selected by the logic circuit of the reactor emergency stop device,
It sends the operation signal of each scrum pilot valve corresponding to the modes such as single rod scrum and scrum. The evaluation device 81 compares the operation signal output from the activation device 86 with the operation signal stored in the storage device 80, and the activation device 86
The scrum pilot valve that does not match the operation signal of is extracted and the operator is notified by the alarm device 85.

Note that (d) and (e) in the above-described discrimination device 77
Even when an abnormal condition such as the one described above occurs, the soundness of each scrum pilot valve is automatically evaluated by the evaluation device 81, and when a failure is found, the warning indicator lamp 84 lights up and an alarm such as a buzzer sounds. Device 85 is activated.

According to the operation confirmation device for the scrum pilot valve having the above-mentioned configuration, the stress strain generated with the change in the opening direction of the scrum pilot valve is electrically detected by the strain gauge, and the characteristic value of the signal waveform of the scram pilot valve is used. The operating state is determined. In other words, the scrum circuit is tripped during an operation test, and the operating state of the valve is determined based on the strain conditions occurring in the valve box and the yoke before and after the trip. The mechanical integrity of the valve can be confirmed at the same time.

In addition, the operation data of all scrum pilot valves are individually stored and updated for each operation test, and the contents are appropriately displayed to the operator by the display device, which facilitates the maintenance and management of the reactor emergency stop device. Also, the reliability of the scrum operation is improved.

Further, even during the reactor operation, the operation can be confirmed in a short time by any scram pilot valve by the valve selection device, and the operation data of the evaluation device is compared and evaluated with the operation data stored in the storage device in advance. The function allows the soundness of the operating condition of the scrum pilot valve to be instantly evaluated. Those whose health is deteriorated are automatically extracted and notified to the operator by a warning device, so that a failure can be easily found and maintenance operation management can be simplified.

〔The invention's effect〕

According to the operation confirmation device of the scrum pilot valve of the present invention, the strain gauge is attached to each scrum pilot valve, and the strain generated with the change in the opening direction of the valve is electrically detected, and the detection signal thereof is detected. By incorporating a device that automatically evaluates and records the operating condition and the soundness of the scrum pilot valve, the conventional method, which only checks the electrical soundness of the scrum circuit during the operation test, has been improved. Furthermore, the mechanical integrity of the scrum pilot, which is the core of the reactor scrum operation, can be confirmed simultaneously within a short time. Therefore, it is possible to improve the reliability of the reactor emergency stop device and significantly simplify the maintenance management work.

In addition, it has a system that instantly judges and evaluates the soundness of the operating conditions of many scrum pilot valves and automatically notifies the operator, and can detect abnormalities of the scrum pilot valve early, so work plans Makes it easier to plan
In addition, a quick repair system is available. Therefore, the reactor shutdown period for periodic inspection, which is the repair work period, can be shortened, and the operating rate of the nuclear power plant can be substantially improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of an operation confirmation device for a scrum pilot valve according to the present invention, FIG. 2 is a front view showing a state in which a strain gauge is attached to a scrum pilot valve, and FIG. 3 is a scrum pilot. It is a graph which shows the change of the strain with respect to the opening degree change of a valve, (a), (b) is a graph which shows the change of the strain in a yoke part of a scrum pilot valve, and a valve box bottom part, respectively, and FIG. FIG. 5 is a system diagram showing the configuration of the apparatus, and FIG. 5 is a circuit diagram showing the configuration of the scrum circuit of the reactor emergency stop apparatus. 1 ... Reactor vessel, 2 ... Reactor core, 3 ... Light water, 4A-4N ...
… Control rod, 5A-5N …… Control rod drive mechanism (CRD), 6A ……
Extraction piping, 7A ... Insertion piping, 8A ... Scrum outlet valve, 9A
…… Scrum inlet valve, 10A …… Driving water discharge pipe, 11A ……
Drive water insertion pipe, 12A …… Scrum valve air pipe, 13A ……
Scrum pilot valve I, 14A ... Scrum pilot valve II, 15A, 16A ... Three-way solenoid valve, 17A ... Air header, 18
A ... Exhaust pipe, 19A ... Water pressure control unit (HCU), 20 ...
… Scrum circuit I, 21 …… Scrum circuit II, 23,24,25,3
6,37,38 …… Logic circuit, 26,27,28,39,40,41 …… Contactor,
26A, 27A, 28A, 39A, 40A, 41A ... Contact, 29A-29N ... Single rod scrum switch, 30,31,43,44 ... Power supply, 5
0 …… Scrum pilot valve, 51 …… Valve box, 52 …… Valve lid, 53 …… Valve rod, 54 …… Yoke, 55 …… Iron core, 56 …… Electromagnetic coil, 57 …… Spring, 71A to 71N, 72A to 72N ……
Strain gauge, 73 ... Scrum pilot valve operation confirmation device, 74 ... Signal switching device, 75, 76 ... Strain measuring device, 7
7 ... discrimination device, 78 ... valve identification device, 79 ... valve selection device, 80 ... storage device, 81 ... evaluation device, 82 ... transmission device, 83 ... reception device, 84 ... display device, 85 …… Alarm device, 86 …… Starting device, 87,88 …… Scrum signal.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location G21C 17/003 GDB G21D 1/00 GDB 9216-2G G21C 9/02 GDB Z G21D 1/00 GDB V

Claims (2)

[Claims] 1. A strain gauge that is attached to a scrum pilot valve and detects strain generated as the scram pilot valve opens and closes as a strain signal, and a strain signal transmitted from the strain gauge is switched for each scrum pilot valve. A signal switching device, a strain measuring device that measures a strain signal as a voltage change, a discriminating device that determines the operating state of the scrum pilot valve based on the signal waveform of the voltage change, and the operating state is identified as operating data for each scrum pilot valve. Valve identifying device, a valve selecting device for inputting a signal for sequentially selecting a scrum pilot valve to be subjected to an operation test to the signal switching device and the valve identifying device, and a storage device for updating and storing operation data of each scrum pilot valve. And a display for displaying the operation data of each scrum pilot valve output from the storage device to the operator. And the evaluation device that evaluates the soundness of the operation of each scrum pilot valve based on the operation data output from the storage device, and confirms the soundness of the operation of the scrum pilot valve during a reactor emergency shutdown. Characteristic scrum pilot valve operation confirmation device. 2. The operation confirmation device for a scrum pilot valve according to claim 1, wherein the strain gauge is attached to at least two places of the valve box bottom and the yoke of each scrum pilot valve.