JPH0277691A - Reactor protection device - Google Patents

Abstract

PURPOSE:To reduce an operation abnormality and to improve safety by arrang ing two three-way valves between a check valve and a backup scram pilot valve to provide a protection device for actuating an electromagnetic solenoid for driving respective three-way valves. CONSTITUTION:A protection device 30 is inserted in the downstream side of a backup scram pilot valve 13A and a check valve 22, two three-way valves 31A, 31B are connected in series, a check valve 22' is joined parallelly, further a check valve 22'' is provided in parallel with the valve 31A and electromagnetic solenoids 32A, 32B are electrically connected to a logic circuit 33. The signal which indicates 'reactor pressure high' or 'reactor water level low' is input in the circuit 33. When two logic circuits in the circuit 33 are realized simultaneously, the solenoids 32A, 32B is in a condition to excite, the valves 31A, 31B are actuated and pressure air of scram valve air piping 11A-11N is exhausted from an exhaust pipes 34A, 34B by an output signal from the circuit 33. As the result, a scram inlet valve 10A and a scram outlet valve 9A are opened to rapidly insert all control rods 4A-4N in a reactor core 2.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a nuclear reactor protection device that suppresses the reactor output by urgently inserting control rods when an abnormality occurs in the reactor of a nuclear power plant. .

(Conventional technology) Reactor protection equipment in nuclear power plants.

This is a device that suppresses the reactivity of a nuclear reactor by urgently inserting control rods in the event of an abnormality that requires the shutdown of the reactor.

Therefore, the reactor protection device is required to operate reliably by detecting abnormal signals from various sensors. On the other hand, it is undesirable for the operation of the reactor to stop power generation due to a malfunction of the reactor protection device.Therefore, the equipment used to insert the control rods from the sensor should be redundant and have high reliability. It is designed like this.

FIG. 3 is a block diagram of a conventional nuclear reactor protection system, in which a reactor pressure vessel 1 has a reactor core 2 and is filled with light water 3.

The reactor core 2 mainly consists of fuel rods (not shown) and control rods 4A to 4N.6 In a normal 1G00,000kW class nuclear reactor,
Approximately 200 control rods are provided, and each control rod penetrates the reactor pressure vessel 1 and is connected to a hydraulic control rod drive mechanism 5.
Control rods 4A to 4N are driven by A to 5N.

One of the approximately 200 control rod drive mechanisms 5A to 5N
The operation will be explained using a stand as an example. In the case of a boiling water type nuclear reactor, the control rod drive mechanism 5A is a type of piston structure that utilizes water pressure, and an extraction pipe 6A is connected to the upper side of the piston, and an insertion pipe 7A is connected to the lower side of the piston.

The former piping is connected to the direction control unit 8A and the scram outlet valve 9.
A to the drive water discharge vessel 20, the latter piping being connected to the control rod drive water filling device 19A via the directional control unit 8A and the scram inlet valve 10A. When driving water flows in from the extraction pipe 6A, the control rod drive mechanism 5A pulls out the control rod 4A from the reactor core 2 and increases the reactor output. Conversely, when driving water flows in from the insertion pipe 7A, the control rod 4
A is inserted into the reactor core 2 and the reactor power is reduced. The opening and closing of the scram inlet valve 10A and the scram outlet valve 9A are controlled by air pressure, and the air pressure is controlled by the scram pilot valve 12A installed in the scram valve air piping 11A and the backup scram pilot valve A installed upstream thereof. 13A, which is also controlled by backup scram pilot valves B and 13B.

The scram pilot valve 12A is a solenoid valve solenoid A,
It is a three-way valve whose opening direction is controlled by two solenoid valves 15A, 16A and 2 solenoid valves B and 16A.
If 5A and 16A are in a non-energized state, the valve is in an exhaust state, and if either one is in an energized state or both are in an energized state, the valve is in a venting state. In addition, the backup scram pilot valves A and 13B and the backup scram pilot valves B and 13B are three-way valves whose opening directions are controlled by solenoid valve solenoids C and 17A and solenoid valve solenoids D and 17B, respectively, and the solenoid valve solenoids are not energized. In this state, the valve is in the ventilation state, and in the energized state, the valve is in the exhaust state. In this way, the scram pilot valve 12A and the backup scram pilot valve 13A.

The reason why the operation of the electromagnetic valve solenoid in 13B is set to be reversed for energization and non-excitation is to ensure redundancy in the event of power loss.

In Section 22, the operations of the scram pilot valve 12A and backup scram pilot valves 13A and 13B will be explained. During reactor power operation, solenoid valve solenoid A
, 15A, solenoid valve solenoid B, 16A are in the excited state,
Solenoid valve solenoid C, 17A, solenoid valve solenoid D, 1
7B is in a non-energized state, therefore, the scram pilot valve 12A and the backup scram pilot valve A, 13
A, and backup scram pilot valve B, 13B
Both are in the venting state and air pressure is applied from the air supply source 14, so the scram inlet valve 10A and the scram outlet valve 9A
is in a closed state. Solenoid valve solenoids A and 15A and solenoid valve solenoids B and 16A are logic circuit A shown in FIG. 4, respectively.
, 18A i It is excited by the output signal of logic circuits B and 18B, and if an abnormality occurs in the reactor, logic circuits A and 18A
Then, the output signals of the logic circuits B and 18B disappear, and the opening direction of the scram pilot valve 12A is switched. As a result, the air in the scram valve air piping 11A is exhausted through the exhaust 923A, and the previously closed scram inlet valve 10A and scram outlet valve 9A open. When these two scram valves open, the control rod drive water filling device 19A High-pressure driving water passes through the insertion pipe 7A and flows into the control rod drive mechanism 5A. At this time, the drive water from the upper part of the control rod drive mechanism 5A passes through the withdrawal pipe 6A and the open scram outlet valve 9A, and the drive water is discharged from the upper part of the control rod drive mechanism 5A. It is discharged into the container 20. As a result, the control rods 4A are quickly inserted into the reactor core 2, and the output of the reactor is reduced.

Also, like the scram pilot valve 12A, the control rod 4
Backup scram pilot valves A, 13A and backup scram pilot valves B, 13B are devices for rapidly inserting the scram pilot valves 12A to 12N. When the reactor is in power operation like the scram pilot valve 12A, the valves open in the direction of passing pressurized air from the air supply source 14, and each solenoid valve solenoid C, 17A and solenoid valve solenoid D.

17B is non-excited. For this reason, when there is an output signal from the reactor protection device, the piping configuration is such that all control rods 4A to 4N can be inserted into the reactor core 2 in an emergency if any of the backup scram pilot valves is energized. This is a backup device that takes into consideration the case where even one valve does not operate. In addition, backup scram pilot valve A.

13A and backup scram pilot valve B, 13B
Solenoid valve solenoid C, 17A and solenoid valve solenoid D.

17B is the logic circuit A, 18A and the logic circuit B, 18.
If B holds true at the same time, that is, logic circuit A & B 2
1 is established and the backup scram pilot valve 13A
, 13B, the air from the scram valve air piping 11A to 11N is discharged from the exhaust pipes 23'A, 2.
3'B, and the control rods 4A to 4N are rapidly inserted into the reactor core 2 in the same manner as described for the scram pilot valve 12A.

FIG. 4 is a circuit configuration diagram of a logic circuit, and is logic circuit A.

18A is constituted by an AND circuit of trip logic A1 channel 24 and trip logic A2 channel 25,
When this AND circuit is established, the scram pilot valve 12
Solenoid valve solenoid A, 15A of A is energized. The logic circuit B, 18B is constituted by an AND circuit of the trip logic 81 channel 26 and the trip logic 82 channel 27, and when this AND circuit is established, the solenoid valve solenoid B, 16G of the scram pilot valve 12A is energized.

Each channel of the above trip logic is based on reactor pressure,
This circuit receives parameters such as reactor water level and core neutron flux, and detects abnormalities in the 1M sub-reactor. If these parameters are sound, logic circuit A, 18A and logic circuit B, 18B are established, and solenoid valve solenoid A, 15
A and solenoid valve solenoid B.

Each output signal is output to 16A.

Also, a backup scram pilot valve 13A.

To 13B, logic circuit A, 18A and logic circuit B, 1
8B is an AND circuit of each NOT signal, and a logic circuit A&
B21 does not emit an output signal, contrary to the solenoid valve solenoids 15A and 16A of the scram pilot valve 12A.

That is, during power operation of the reactor, the backup scram pilot valves A, 13A, the backup scram pilot valves B, 13B, the electromagnetic valve solenoids C, 17A, and the electromagnetic valve solenoids D, 17B are in a non-energized state. These are solenoid valve solenoid A, 15A, and solenoid valve solenoid B if there is no abnormality in the reactor during power operation of the reactor.

16A is in an energized state, and solenoid valve solenoids C, 17A, and solenoid valve solenoids D and 17B are in a non-energized state.If there is an abnormality in the reactor, each solenoid valve solenoid will be in the opposite state to the above. Become.

Note that FIG. 4 only shows logic circuits that operate automatically, and omits logic circuits that are operated manually.

(Problems to be Solved by the Invention) Even in conventional nuclear reactor protection devices, the scram pilot valve 12A, the backup scram pilot valve 13A,
13B is malfunctioning, or even if they are healthy, the logic circuit for operating it or the power supply failure of the logic circuit occurs.

Emergency insertion of control rods 4A to 4N may not be possible. Although the probability of such a situation is extremely low, due to the nature of nuclear power plants, it is necessary to avoid operational abnormalities as much as possible, so measures to further reduce the accident rate have been desired.

The present invention has been made in view of the above, and its purpose is to reduce operational abnormalities in nuclear power plants, improve safety, and at the same time, prevent unnecessary shutdown of the reactor and improve operational reliability. The purpose of the present invention is to provide a nuclear reactor protection device with improved performance.

[Structure of the invention]

(Means for solving problem m1) A protection device including a power supply, two independent three-way valves, a check valve, and a logic circuit is installed in the conventional reactor protection device.

(Function) Even if the conventional reactor protection device does not operate due to a malfunction, the protection device of the present invention, which is installed independently, inputs the abnormality signal of the reactor and operates the three-way valve, and the scram pilot Release the pressure air to the valve.

Emergency insertion of control rods suppresses the reactivity of the reactor core and safely reduces the reactor's output.

(Example) An example of the present invention will be described with reference to the drawings. Note that the same components as those in the prior art described above are given the same reference numerals, and detailed explanations will be omitted.

FIG. 1 is a block diagram of the reactor protection system, showing the state of the valves during normal operation. The protection device 30 in FIG. 1 is two three-way valves inserted downstream of the backup scram pilot valves A and 13A and the check valve 22 of the conventional reactor protection device shown in FIG. ARI valve A, 31A and AR
I valves B and 31B are connected in series, and A
A check valve 22' is provided in parallel to the RI valves 31A and 31B, and a check valve 221 is provided in parallel only to the ARI valves A and 31A.
A solenoid valve solenoid E that drives ARI valve A, 31A and ARI valve B, 31B, 32A and solenoid valve solenoid F,
32B is electrically connected to the logic circuit 33.

Furthermore, exhaust pipes 34A and 34B are connected to ARI valves A and 31A and ARI valves B and 31B, respectively.
The ARI valves 31A and 31B are three-way valves having the same structure as the backup scram pilot valves 13A and 13B described above.

Pressurized air is supplied from the air supply source 14 to the backup scram pilot valves B, 13B, the same backup scram pilot valves A, 13A, and the ARI valves B, 31B,
Air piping 11 passes through ARI valves A and 31A in sequence, passes through a scram pilot valve 12A such as a control rod drive mechanism 5A, and reaches a scram inlet valve 10A and a scram outlet valve 9A.
A etc. are formed. Also, the backup scram pilot valves A, 13A, ARI valves B, 31B, and ARI valves A, 31A are bypassed via the check valve 22.

Air piping is provided for exhausting air from the exhaust pipes 23'B of the backup scram pilot valves B and 13B.

Similarly, the ARI valves B and 31 are connected via the check valve 22'.
It is also provided with air piping that can bypass ARI valves A and 31A and ARI valves A and 31A via a check valve 22'.

FIG. 2 is a circuit configuration diagram of the logic circuit. The inside of the logic circuit 33 is composed of logic circuits A and 35A and logic circuits B and 35B, and these inner ring circuits A and 35A are used for the reactor pressure high A signal 3.
6A, also C signal 36C, M reactor water level low A signal 37A
, similarly constituted by an OR circuit of C signal 37C, and logic circuits B and 35B are constituted by an OR circuit of reactor pressure high B signal 36B, also D signal 36D, reactor water level B signal 37B, and likewise D signal 36D. There is.

Here, "reactor pressure high" is used as a parameter for maintaining the integrity of the reactor pressure vessel 1, and "reactor water level low" is used as a parameter for maintaining the integrity of the reactor pressure vessel 1.
is adopted as a parameter to prevent fuel cladding damage. Each signal of this logic circuit 33 is made independent as a separate circuit from the logic circuit, detection instrument, logic power supply, etc. of the conventional reactor protection system.

It is configured to operate without any effect even in the event of multiple failures of conventional equipment.

Next, the effect of the above configuration will be explained. First, when the reactor is in normal output operation and there is no abnormality, the solenoid valve solenoids E, 32A and solenoid valve solenoids F, 32B are activated.
Since there is no output signal from the logic circuit 33 provided separately from the logic circuits A and 18A and the logic circuits B and 18B, it is in a non-excited state. At this time, ARI valve A, 31A
and ARI valves B and 31B are in the ventilation state, and the pressurized air that has passed through the backup scram pilot valves B and 13B and the backup scram pilot valves A and 13A reaches the scram inlet valve 10A and the scram outlet valve 9A, keeping both valves closed. do. As a result, the control rod 4A remains stationary in the withdrawal direction.

Next, in the unlikely event that an abnormality occurs in the reactor, signals of "reactor pressure high" and "reactor water level low" are input to the logic circuit 33 as the abnormality signals, and the logic circuits A, 35A and logic circuit B
, 35B are established at the same time, A&B is established, and the output signal from the logic circuit 33 causes the solenoid valve solenoids E, 32
A and solenoid valve solenoids F and 32B are in an excited state. As a result, the ARE valves A, 31A, ARI4B, 31B operate, and the pressurized air in the scram valve air pipes Ie11A to 11N is discharged from the exhaust pipes 34A, 34B. As a result, the scram valves of each control rod drive mechanism 5A to 5N! The OA and scram outlet valve 9A are open, and high-pressure driving water is inserted from the control rod driving water filling bag @ 19A into the piping 7.
A flows into the control rod drive mechanisms 5A to 5N, and all of the control rods 4A to 4N are rapidly inserted into the reactor core 2. Of course,
Logic circuit A&B of the above-mentioned conventional reactor protection device, 21
The backup scram pilot valve 13A is triggered by an abnormal signal input to the back-up scram pilot valve 13A.

13B etc. operate normally, it is obvious that the reactor can be sufficiently protected even if the protection device 3° does not operate.

In addition, if ARI valves A, 31A, ARI valves B and 31B do not operate and the backup scram pilot valves 13A and 13B, which are conventional protection devices, operate and the opening direction of the valves is switched to the discharge side, the pressurized air will ARI valve A in venting state,
31A, ARI valve B, and 31B, it flows from the scram pilot valve 12A side to the backup pilot valves 13A and 13B side, contrary to the normal state. However, in the above case, the three-way valve used for ARI valves 31A and 31B may close regardless of the state of the solenoid valve solenoid due to its structure, and in this case it is considered that the discharge of pressurized air may be prevented. but.

The bypass line via the check valves 22' and 22' can discharge the pressurized air in the scram valve air pipes 11A to 11N without any problem even in such a case. In addition, the bypass line via the check valve 22 provided in the conventional reactor protection device is also used as the backup scram pilot valve B, 13B.
It is provided with consideration to the operation of only one unit.

As mentioned above, with conventional reactor protection devices, the probability of the device not operating due to multiple failures is extremely low, but even in the unlikely event that it occurs, it is not possible to respond to the operator's judgment and operation. In this example, reactor pressure and reactor water level are used as parameters for detecting a control rod insertion failure, and an independently installed device automatically inserts control rods to maintain the integrity of the reactor. There is. Therefore, the probability of the above-mentioned problems can be reduced. In addition, both the ARI valve connection method and the bypass line via the check valve as shown in one embodiment can be easily added to conventional equipment without significantly changing the conventional reactor protection equipment. is possible. Furthermore, malfunctions are also dealt with by making the logic circuits redundant.

〔Effect of the invention〕

As described above, according to the present invention, it is taken into consideration that conventional protection devices will not operate in the event of a nuclear reactor abnormality, and although the risk is low even with conventional technology, the safety is higher due to the nature of nuclear power plants. is desired. For example, numerically, the present invention reduces the risk by about 10-1, and considering this configuration, the effect is extremely high. Also, malfunctions are of course dealt with by making the circuit redundant, and nuclear power generation plants This has the effect of increasing operating efficiency and safety.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of the present invention, Fig. 2 is a circuit block diagram of a logic circuit of the protection device shown in Fig. 1, Fig. 3 is a block diagram of a conventional reactor protection device, and Fig. 4 is a block diagram of a conventional reactor protection device. 4 is a circuit configuration diagram of the logic circuit of FIG. 3. FIG. 4A~4N...control rod, 5A~5N...control rod drive mechanism. 6A... Pull out piping, 7A... Insertion piping, 8
A... Directional control unit, 9A... Scram outlet valve, 10A... Scram inlet valve. 11A~IIN...Scram valve air piping. 12A...Scram pilot valve, 13A...Backup scram pilot valve A. 13B...Backup scram pilot valve B, 1
4...Air supply source, 15A...Solenoid valve solenoid A, 16A...Solenoid valve solenoid B. 17A... Solenoid valve solenoid C1 17B... Solenoid valve solenoid D. 22.22', 22'... check valve, 23, 23'A
, 23'B, 34A, 34B...exhaust pipe, 30
...Protective device, 31A...ARI valve A, 31B
...ARI valve B, 32A...Solenoid valve solenoid E
. 32B... Solenoid valve solenoid F, 33... Logic circuit, 35A... Logic circuit A, 35B... Logic circuit B0 agent Patent attorney Norifu Ogo Figure 3 Figure 4

Claims (1)

[Claims] Air piping that supplies pressurized air to the scram valve that controls the driving water that is supplied to the control rod drive mechanism and the scram pilot valve that controls the pressurized air for emergency insertion of control rods in nuclear reactors such as nuclear power plants. In a reactor protection system in which a back-up scram pilot valve and a check valve are connected in series, the check valve and the back-up scram pilot valve are connected downstream of the check valve and the back-up scram pilot valve. In this system, two three-way valves are arranged in series, and check valves are installed in parallel for these two three-way valves and one of them, and the electromagnetic valve solenoids that drive each three-way valve are used to detect reactor abnormalities. A nuclear reactor protection device characterized in that a protection device is provided that is independent of a power source and the like made up of a logic circuit that operates the electromagnetic valve solenoid when a signal is input.