JPS63234193A - Safety protective device for nuclear reactor - 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 [Industrial Application Field] The present invention relates to a nuclear reactor safety protection device, and more particularly to a nuclear reactor safety protection device using a scram solenoid valve having two excitation solenoids.

[Conventional technology]

In order to ensure the safety of the nuclear reactor, a nuclear coupler is equipped with a safety protection device to prevent abnormal transient conditions from occurring and potentially affecting the plant.

For example, "Atomic Band Book" (Ohmsha).

(1986) pages 263 to 267 describe the functions and configuration of the safety protection device.

The structural concept is shown in FIG.

In the figure, signal processing devices 1 to 4 include each sensor A 1
"NtyAx~Nx, Aa"
Take in the output signal from Na, A4 to Na,
Each signal processing device 1 to 4 receives one of all input signals.
If any value exceeds the specified value, a trip signal is output. Each signal processing device! The trip signals outputted from 1 to 4 are outputted to the excitation solenoids 16 and 17 of the scram solenoid valve 18 via OR gates 36 and 37. The scram solenoid valve 18 scrams the reactor when both excitation solenoids 16 and 17 are de-energized. That is, the portion constituted by the OR gates 36 and 37 and the excitation solenoids 16 and 17 has a 1-out-of-2-twice majority logic. However, this is a configuration that operates with logic "0".

[Problem that the invention seeks to solve]

The signal processing devices 1 to 4, which take in signals from multiple sensors and process them, are each independent, but in the unlikely event that a failure occurs, the failure channel (1/4) is put into operation and repaired. As stipulated in the safety regulations, in the 1-out-of-2-twice logic, if one more unit fails, the logic will immediately hold true, leading to a reactor scram.

Additionally, if another single erroneous signal occurs during a test of the power circuit, which consists of a relay for de-energizing the scram electromagnetic solenoid, a reactor scram occurs, so conventionally this power circuit part was tested. It had no functionality. In order to further improve the reliability of the IfX reactor safety protection system, it is desirable to test the power circuit without causing false scrams during operation.

The purpose of the present invention is to improve the structure of the current scram solenoid valve by adding 27
Even if you combine out-of-4 logic and disconnect one signal processing system, you can still combine 27 out-of-3 logic with other trip signals while satisfying the single fault criterion. To provide a highly reliable nuclear reactor safety protection device capable of testing a power circuit portion without causing a reactor scram even if an erroneous signal occurs.

[Means for solving problems]

In order to achieve the above object, the present invention includes quadruple redundant sensors and four signal processing systems that independently capture the output signals of these sensors and output a trip signal when each signal exceeds a specified value. system and 8 opening/closing means that open and close according to signals from 4 signal processing systems, allowing 2 out of 4
A first opening/closing means forming a logic, and a second opening/closing means forming a 2-out-of-4 logic by eight opening/closing means that open and close in response to signals from the four signal processing systems separately from the first opening/closing means. and two excitation solenoids connected to the first opening/closing means section and the second opening/closing means section, respectively, and are activated when a trip signal is issued from at least two signal processing systems among the four signal processing systems. This paper proposes a nuclear reactor safety protection device consisting of a scram solenoid valve.

The first and second opening/closing means sections each include four switching circuits that cut off signals from each signal processing system to each opening/closing means in order to test the health of each of the eight opening/closing means.

In addition, each of the four signal processing systems is specifically:
a signal processing circuit that takes in the output signal of the sensor and outputs a trip signal; a switching circuit that includes a power source that generates a voltage at the same level as the trip signal of the signal processing circuit and is capable of switching between the trip signal and the voltage; and a signal processing circuit. It consists of a diagnostic circuit that diagnoses whether the circuit is healthy or not, and if it is not healthy, switches the switching circuit to the power supply side.

Furthermore, each of the first and second opening/closing means units may include an excitation display circuit that indicates the presence or absence of an excitation solenoid current between each excitation coil.

It is preferable that the excitation display circuit includes an isolation transformer, through which the excitation solenoid current is extracted and applied to the display.

[Effect]

As already mentioned in Fig. 5, a signal processing device that takes in signals from multiple sensors and processes them is composed of four independent
It is composed of two systems. Because the four systems are independent in this way, the 1-out-of-2-twice configuration is
Easy to expand to an out-of-four configuration.

When comparing the false scrum probability between the 1-out-of-2-twice configuration and the 27-out-of-4 configuration, the 2-out-of-4 configuration is lower, and the 2-out-of-4 configuration is preferable.

In the case of 1-out-of-2-twice logic, the safety regulations stipulate that the faulty channel (1/4) should be put into operation and repaired, and if one faults, the logic immediately holds; In the case of out-of-4 logic, exclude the faulty channel (1/4) and use 2 out-of-3 logic.
This is because redundancy is maintained because repairs can be made in the logical state.

In other words, in the current atomic couplant, the safety of the atomic couplant is maintained with a configuration in which the scram solenoid valve corresponds to the 17-out-of-2-twice logic, but if a 2-out-of-4 logic configuration is used, the reliability of the plant is reduced. can be further improved.

Also, in the prior art, if another single false signal occurs during a scram circuit test, it will lead to a reactor scram. In contrast, in the present invention, even if a single erroneous signal is emitted from the signal processing system during a surveillance test, for example, while individually testing the relays etc. that constitute the first switching means section, Since the second opening/closing means has 2-out-of-4 logic, it does not de-energize one of the excitation solenoids.Therefore, the two excitation solenoids do not become de-energized at the same time, so the scram solenoid valve does not operate and a single false signal Depending on the situation, the reactor scram may not be reached.

〔Example〕

Next, specific embodiments of the nuclear reactor safety protection device according to the present invention will be described with reference to FIGS. 1 to 4.

FIG. 1 is a block diagram showing the overall configuration of a nuclear reactor safety protection device according to the present invention. There are four signal processing systems each consisting of one signal processing device, one switching circuit, and one diagnostic device (for example, a signal processing device 11, a switching circuit 19A, and a diagnostic device 22A). The signal processing device 1 has sensors A1 to Nl,
Signal processing device! 2 is a signal processing device for sensors A1 to N2! 3 is the sensor A3 to Nδ, and the signal processing device 4 is the sensor A
4 to N4. Here, four sensors denoted by the same alphabet (e.g. At, Age As
, No. A) are arranged closely and measure the same state quantity of the atomic couplet. In this example, one sensor corresponds to one signal processing device, but four sensor signals ( For example, the rationality of the signal may be checked within the signal processing device by inputting A1 to A a ).

The signal processing devices 1 to 4 each take in the signals output from the redundant sensors, perform arithmetic processing on them, and each output a trip signal a''d for scramming the plant when the result exceeds a specified value.

The switching circuit 19A includes a changeover switch 20 and a power source 21, as shown in FIG. The changeover switch 20 includes fixed contacts 2OA and 20B, a fixed terminal 20G, and a movable contact 20D that is always connected to the fixed terminal 20G. The power source 21 is connected to the fixed contact 20B. Switching circuit 19
B-190 also has the same structure as 19A. Switching circuit 19
Each fixed contact 2OA of A to 19D is connected to a signal processing device 1 to 4.
are connected to the output ends of each.

The power circuit 5 shown in FIG. 3 includes two opening/closing means sections 5A and 5B connected in parallel.

Each opening/closing means section 5A, 5B is composed of eight relays (or contactors), their test switching circuits, and an excitation display lamp circuit for determining test results. The opening/closing means section 5A includes a series-parallel circuit in which a parallel circuit of relays 8 and 9, a series circuit of relays 10 and 12, and a series circuit of relays 11 and 13 are connected in parallel, and a relay 14.
and relay 15 are connected in series.

Relay 8 and relay 9 are connected to power supply 6.

Relay 8 and relay 10 are connected to a test switching circuit (
(FIG. 4) It is connected to the fixed terminal 20C of the signal switching circuit 19A via 23A.

Similarly, a trip signal is input to relay 9 and relay 12 from switching circuit 19B via switching circuit 23B. Relay 11 and relay 14 have switching circuit 23G.
A trip signal C is input from the switching circuit 19C via the switching circuit 19C. Relay 13 and relay 15 have a switching circuit 23
A trip signal d is input from the switching circuit 190 via the switching circuit 190. Relay 14 and relay 15 are connected to excitation solenoid 16 via excitation indicator lamp circuit 25 .

The test switching circuit 23A includes a changeover switch 27, as shown in FIG. The changeover switch 27 has fixed contacts 27A, 27B, and a fixed terminal 27C.

It consists of a movable contact 27D that is always connected to this fixed terminal 27G. Fixed contact 27B is grounded. Switching circuit 2
3B to 230 also have the same structure as the switching circuit 23A.

The excitation indicator lamp circuit 25 determines the presence or absence of an output current from the opening/closing means section 5A. To prevent failure of the lamp display circuit from affecting the main circuit.

A lamp 25B is connected via an isolation transformer 25A.

Up to this point, the configuration of the opening/closing means section 5A has been explained, but the relay 28 of the second opening/closing means section 5B arranged in parallel therewith has been described.
~Relay 35. Power supply 7. Test changeover switch 24A~2
4D, the excitation indicator lamp circuit 26 has a similar configuration, and supplies current to the excitation solenoid 17 intermittently.

During normal operation of the nuclear coupler, relays 8 to 1
5 and relays 28 to 35 are closed, the excitation indicator lamps 25, 26 are lit, and the excitation solenoids 16, 17 are energized, so the scram solenoid valve 18 is in an inoperative state.

While each signal processing device 1 to 4 is functioning normally, each signal processing device 1 to 4 is
When trip signals a - d are output from contacts 8 and 1
0, 28.30 is trip signal 8, contacts 9, 12
, 29 and 32 are connected to contacts 11 and 14 by the trip signal.
, 31 and 34 are connected to contacts 13 and 15 by trip signal C.
, 33 and 35 are opened by the trip signal d, and the excitation solenoids 16 and 17 are de-energized.

The excitation indicator lamps 25, 26 go out. As a result, the scram solenoid valve 18 operates, resulting in a reactor scram.

As is clear from the logical configuration of FIG. 3, the two switching means sections 5A and 5B of the power circuit 5 each have 8 relays and 27 out of 4 logics. therefore,
If at least two of the four trip signals at byc,d are issued.

A reactor scram occurs.

Next, in the reactor safety protection device of this embodiment, if one signal processing device breaks down or due to maintenance work,
This shows that even if one signal processing device is disconnected, a 2-out-of-3 logic can be configured by sending the signals of the remaining three signal processing devices to the power circuit.

This can be achieved by constructing one signal processing system including a signal processing device, a switching circuit, and an abnormality diagnosis device, as shown in FIG. That is, for example, an abnormality diagnosis device that inputs the status signal of the signal processing bag fil! 22A determines that there is an abnormality in the signal processing device II based on the input signal,
The abnormality diagnosis device ff122A has a switching circuit 19 shown in FIG.
Disconnect from the movable contact 20D of the changeover switch 20 of A,
Connect to fixed contact 20B. The diagnostic devices 22A to 22D can be realized by various means (for example, Japanese Patent Application Laid-Open No.
51393), the control of this changeover switch 20 is as follows:
It can also be operated by an operator, and is operated when performing maintenance on the signal processing device or the sensor input to it. When connected to the fixed contact 20B, since the power supply 21 is a DC power supply, it outputs a logic "1", that is, a relay closing request signal.

In the power circuit shown in Fig. 3, for example, if a=1 is maintained, relays 8, 10, 28, and 30 are kept closed, so the remaining S, C, and D signals cause the 27 out of 3 logic to be activated. Realized. Therefore, even if one of S, C, and D issues a fault signal, the reactor may erroneously perform a reactor scram when the nuclear coupler is normal, or conversely, it may not be possible to perform a reactor scram when a scram is required due to an abnormality in the nuclear coupler. can be avoided.

The example above is a signal processing bag! ! 1, but other signal processing bags! The same applies to the case of separating 2, 3, and 4.

Furthermore, it is shown that testing of the opening and closing conditions of the relays of the first switching means section 5A and the second switching means section 5B, which constitute the power circuit shown in FIG. 3, can be performed even during plant operation.

When any two of the switching circuits 23A to 23D shown in FIG. 4 are switched to the ground side, 2 out of 4 logic is realized, the solenoid excitation current is cut off, and the excitation indicator lamp 25 goes out. It's normal. If the lights do not turn off in a particular combination, it is obvious that the relay included in that combination has failed and will not open. That is, a
If the excitation indicator lamp does not go out even after the combination of two signals including =O, it indicates that relay 8 or 10 does not open. Below, you can find relays that do not open in the same way.

In this embodiment, even if a single failure occurs in the sensor or the signal processing system when such a test is performed on the first switching means section 5A and the excitation solenoid 16 is demagnetized, the second switching means section 5B also has a 2-out-of-4 logic, so the excitation solenoid 17 is kept in an excited state. As a result, the scram solenoid valve 18 does not operate, and a reactor scram does not occur. Therefore, a surveillance test of the power circuit can be easily performed during operation.

In this example, as shown in FIGS. 1 and 3, there is one set of power circuits, but there are also 2 to 4 sets of power circuits, taking into consideration that the power circuits are evenly distributed in the plane cross section of the reactor. , it is also possible to group the corresponding scram control rods. This grouping helps spread the risk of relay failure and reduces the required capacity of the power supply by suppressing the inrush current when turning on the solenoid excitation current of the reactor safety protection circuit.

Further, in this embodiment, a solenoid valve having two excitation solenoids is shown as an example, but the present invention can also be applied to two series solenoid valves having one excitation solenoid.

〔Effect of the invention〕

According to the invention, in an atomic coupler, the configuration of a solenoid valve with two excitation solenoids or two series solenoid valves with one excitation solenoid remains unchanged,
A system with 2 out of 4 logic can be configured, and
Even if one of the signal processing devices in the system breaks down or is disconnected for maintenance, the system will not malfunction or fail to operate when required. A 2 out of 3 logical configuration can be created.

Furthermore, relay opening/closing tests of power circuits can be easily performed even during plant operation.

Therefore, a nuclear reactor safety protection device with further improved reliability can be obtained.

[Brief explanation of drawings]

1 is a diagram showing the configuration of a signal processing system and a sensor in an embodiment of a nuclear reactor safety protection device according to the present invention; FIG. 2 is a diagram showing a detailed configuration of a switching circuit in the embodiment of FIG. 1; The figure shows the configuration of the power circuit of the embodiment shown in Figure 1, Figure 4 shows the details of the switching circuit for surveillance testing of the power circuit, and Figure 5 shows the configuration of the conventional reactor safety protection device. FIG. A1=Aa*Nz-Na...Sensor, 1-4...Signal processing device, 5...Power circuit,
5A, 5B... Opening/closing means section. 6.7...Power supply, 8~15.28~35...Relay. 16.17...Exciting coil, 18...Scrum power supply, 19A-19B...Switching circuit, 23A-23D. 24A to 24D...Switching circuit for power circuit test, 25
．． 26...Excitation display lamp circuit.

Claims (1)

[Scope of Claims] A single or quadruple redundant sensor; four signal processing systems that each independently captures the output signal of the sensor and outputs a trip signal when each signal exceeds a specified value; a first opening/closing means section that configures a 2-out-of-4 logic by eight switching means that open and close according to signals from the four signal processing systems; and a first switching means section that opens and closes according to signals from the four signal processing systems; a second opening/closing means which constitutes a 2-out-of-4 logic by eight opening/closing means that open and close according to the above-mentioned four signals; A nuclear reactor safety protection device comprising a scram solenoid valve that operates when a trip signal is issued from at least two signal processing systems among the processing systems. 2. In claim 1, the first and second opening/closing means sections transmit signals from each of the signal processing systems to each of the opening/closing means in order to test the health of each of the eight opening/closing means. A nuclear reactor safety protection device characterized by including four switching circuits each for switching off the power. 3. In claim 1 or 2, each of the four signal processing systems includes: a signal processing circuit that takes in the output signal of the sensor and outputs a trip signal; and a trip signal of the signal processing circuit. a switching circuit that includes a power source that generates voltages at the same level and can switch between the trip signal and the voltage; and a switching circuit that diagnoses whether or not the signal processing circuit is healthy and switches the switching circuit to the power source side if it is not healthy. A nuclear reactor safety protection device characterized by comprising a diagnostic circuit. 4. In any one of claims 1 to 3, each of the first and second opening/closing means has an excitation device that indicates the presence or absence of an excitation solenoid current between each of the excitation coils. A nuclear reactor safety protection device characterized by including a display circuit. 5. The nuclear reactor safety protection device according to claim 4, wherein the excitation display circuit includes an isolation transformer that takes out the excitation solenoid current and applies it to an indicator.