JPH0915380A - Compressed air supply equipment for instrumentation at nuclear power plants - Google Patents

Abstract

(57) [Summary] [Purpose] To avoid troubles leading to automatic shutdown of the reactor and to ensure stable operation. [Structure] Air compressor 1, air storage tank 2 and air dehumidifier 3
Are connected in series, and the air dehumidifier 3 is connected to the pressure header 4. A header stop valve 8 connected to the main pressure converter 15, the reactor pressure header 5, the R / W pressure header 6 and the turbine pressure header 7 is connected to the pressure header 4. An unimportant stop valve 10, an automatic shutoff valve 11, a flow restrictor 13, a pressure switch and a local air storage tank 14 are connected to the R / W system pressure header 6 and the turbine system pressure header 7. A reactor system important stop valve 9 and a non-important valve 10 are connected to the reactor system pressure header 5, and an automatic shutoff valve 1 is provided downstream of the reactor system important stop valve 9.
1, flow limiter 13, pressure switch 12, local air storage tank 14 and three-way valve 21 are connected. A three-way valve 21 is connected to a pressure reducing valve 24 from a local compressed air system 23 and a local dehumidifier 22. When the flow rate increases to decrease the pressure due to the non-important loads 17, 18, 19, etc., the flow rate limiter 13 limits the flow rate, and the pressure switch 12 detects the pressure drop and closes the automatic shutoff valve 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compressed air supply facility for instrumentation in a nuclear power plant, which has both a self-isolation function and an accident protection function.

[0002]

2. Description of the Related Art A compressed air system for instrumentation (hereinafter referred to as IA system) is an important facility essential for stable operation of a plant. The IA system consists of a combination of an air compressor, an air storage tank, an air dehumidifier, an air pipe and a valve. Compressed air is supplied to the air operated valve.

Compressed air is also supplied to a scrum valve for automatically stopping the nuclear reactor. When the supply of compressed air becomes unsatisfactory for some reason in the IA system, the air pressure applied to the scrum valve decreases, and when it falls below a certain pressure value, the scrum valve opens and the control rod is inserted into the core to automatically start the reactor. Will stop.

In the IA system, when compressed air cannot be supplied due to an air compressor failure or the like, a compressed air system for internal use (hereinafter SA
It has a multiple defense mechanism that receives compressed air from the system and is backed up.

[0005]

As mentioned above, the IA
The system is an important system that is indispensable for stable operation of the plant, which will automatically shut down the reactor if the supply of compressed air becomes unsatisfactory for some reason.

[0006] The IA system load is very large in the plant, and the IA system air supply pipe is laid all over the plant like a mesh. However, if some trouble occurs in the IA system piping or load and air leaks or jets, the air will continue to flow away.

At this time, the IA system maintains a constant pressure and the function of the IA system is maintained if the amount of loss due to a malfunction is less than the supply capacity of the air compressor, but if the loss exceeds the supply capacity, the IA system is maintained. The pressure drops and the function is lost.

The amount of air used in the IA system is about 5 to 10 Nm ³ / min during normal operation of the plant, and the pipe for distributing this to each load is a thin pipe of stainless steel or copper alloy with a diameter of 50 mm or less. . By design, it can sufficiently withstand internal pressure, but it cannot be said to be strong against external force that damages piping. The external force referred to here is a case where a mechanical force is applied or corrosion caused by an external environmental factor. In this way, it also has the aspect of being relatively fragile equipment.

A piping system such as a blood vessel in an organism has a self-repair ability. When compared to blood vessels, when the blood vessels are cut off, the hemostatic action works to stop the blood loss and repair the blood vessels over time.

Even if the self-repair capability is impossible in the IA system, it is desirable to judge the place where it is washed away and its importance, and to keep the function of the IA system by disconnecting the load if necessary. Does not have such a function.

When the IA system cannot supply compressed air, it is backed up from the SA system, but this is only a self-defense function against the trouble of the source of the IA system.
Even if the SA system backs up, there is a problem that the supply capacity determined by the pipe diameter of the source is limited and cannot be dealt with for a trouble such as breakage of the piping system stretched around the load side.

The present invention has been made to solve the above-mentioned problems, and prevents the plant from being automatically stopped due to the loss of function due to the loss of air flow in the IA system piping or load to ensure stable operation of the plant. The object is to provide a compressed air supply device for instrumentation.

[0013]

The present invention provides an air compressor,
A nuclear power plant that is composed of a combination of an air storage tank, an air dehumidifier, a pressure header, air piping, and valves, and that supplies compressed air to instrumentation equipment, regulating valves, and air operated valves that require compressed air in the nuclear power plant. In the compressed air supply equipment for instrumentation, a main pressure converter is provided in the pressure header, and an automatic shutoff valve, a pressure switch, and a local air storage tank are provided in an air pipe downstream from the pressure header.

Further, according to the present invention, a flow restrictor is provided between the downstream side of the automatic shutoff valve and the pressure switch and the local air storage tank, or a three-way valve is connected downstream of the flow restrictor. However, a local dehumidifier and a pressure reducing valve are connected to a connection port on the side opposite to the downstream load side of the three-way valve.

[0015]

According to the present invention, the IA system is provided with the self-isolation function and the self-defense function, and the important SA is backed up by the local SA system to ensure the stable operation of the plant of the nuclear power plant. That is, the reactor system unimportant load and the R / W system,
When a flow rate increase such as breakage that causes a sudden decrease in pressure occurs in a ventilation air conditioning system, turbine system, etc., the flow rate limiter limits the flow rate and a pressure switch in the vicinity detects the pressure drop,
Close the group's automatic shutoff valves.

If the pressure switch of the IA header is operated at a low pressure when the pressure continues to drop, the automatic shutoff is closed in the order determined in advance according to the degree of importance to prevent the pressure drop of the HCU system (water pressure control unit). To do.

At this time, the load group which is not the broken group maintains its function for a while by the local air storage tank, that is, the accumulator. Isolation of the broken group only by opening the shutoff valve.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of compressed air supply equipment for instrumentation of a nuclear power plant according to the present invention will be described with reference to FIGS. In FIG. 1, the air compressor 1 is connected to the air storage tank 2, the air storage tank 2 is connected to the air dehumidifier 3, and the air dehumidifier 3 is connected.
Is connected to the pressure header 4. A main pressure transducer 15 is connected to the pressure header 4.

The pressure header 4 is connected to the reactor pressure header 5 via the header stop valve 8 to treat radioactive waste (R / W).
The system pressure header and the turbine system pressure header 7 are connected in parallel, and the HCU scram valve load 20, the reactor system important load 16, the reactor system non-important load 17, and the R / W are connected to these pressure headers 5, 6 and 7, respectively. The load groups of the system non-critical load 18 and the turbine system non-critical load 19 are connected. Also,
One of the reactor system important valves 9 is a water pressure control unit (H
CU) Connected to scram valve load 20.

That is, the reactor pressure header 5 includes a group of a plurality of reactor system important stop valves 9 and a plurality of unimportant stop valves 10.
Groups are connected in parallel, and the R / W system pressure header 6 and the turbine system pressure header 7 are connected in series with a group of a plurality of non-important stop valves 10. An automatic shutoff valve 11, a flow restrictor 13, a pressure switch 12 and a local air storage tank 14 are connected to the downstream side of each stop valve 9, 10.

The downstream side of the flow restrictor 13 of the reactor system important stop valve 9 is connected to the reactor system important load 16 and the HCU scrum valve load 20 via a three-way valve 21. The other side of the three-way valve 21 is connected to the pressure reducing valve 24 and the local dehumidifier 22 from the internal compressed air system 23.

Next, each device of the above embodiment will be described along the flow of compressed air. The air compressor 1 compresses the sucked air into about 7 atmospheres. The discharge has considerable pulsation in both pressure and flow rate. The air storage tank 2 stores compressed air. Absorbs pulsation of air compressor discharge and load side pressure and flow rate. The air dehumidifier 3 absorbs moisture in compressed air. Humidity at the outlet is about minus 70 degrees dew point.

The pressure header 4 is an air distributor and distributes compressed air to each building pressure header. A header stop valve 8 is inserted between the pressure header and each building pressure header to enable each isolation.

The reactor pressure header 5 distributes compressed air to each load of the reactor building, and the R / W system pressure header 6 distributes R.
Compressed air is distributed to each load of the / W building, and the turbine system pressure header-7 distributes compressed air to each load of the turbine building.

The reactor system important stop valve 9 is an important load of the reactor system.
The non-important load stop valve 10 is a stop valve of 16 groups, and the non-important load stop valve 10 is a stop valve of non-important loads 17, 18, and 19 groups of the reactor system, the R / W system, and the turbine system.

The HCU scrum valve load 20 is the load of the control rod drive system and hydraulic control system unit. When the IA pressure drops, the air operated valve moves to insert the control rod and automatically shut down the reactor. This is one of the important loads in the nuclear reactor system.

The nuclear reactor system important load 16 is an essential load for stable operation of the plant. Main steam isolation valve, PL
R, MG set oil cooler temperature control valve, CUW / F / D
Flow rate control valve, non-regenerative heat exchange temperature control valve, RCW heat exchange temperature control valve, HVAC isolation valve, etc.

The reactor system non-important load 17 is a load that does not directly affect the operation of the plant and is a load that has a small effect even if the IA is stopped for a short time. The R / W system unimportant load 18 has the same definition as the reactor system unimportant load 17. Basically R /
The W system has nothing to do with the power generation of the plant.

The turbine system non-critical load 19 has the same definition as the reactor system non-critical load 17. Basically, equipment that requires IA of the turbine system is not directly related to power generation in the plant.
The flow rate limiter 13 has the functions of a check valve and a throttle valve. Throttling amount (the limiting amount is determined by the required amount of compressed air for each load group.

The pressure switch 12 sets a pressure value, and outputs a signal to close the automatic shutoff valve 11 when the pressure value becomes less than the set value. HCU
The pressure set value of the scrum valve load 20 is set to a value lower than the pressure at which the scrum valve opens due to low air pressure.

The automatic shutoff valve 11 is an air-operated valve which is normally open and receives a signal from the pressure switch 12 and is closed for a short operating time. The air source is obtained upstream of the non-critical stop valve 10. This valve is open when operating air is lost. Main pressure transducer 15
Also has a pressure switch function. The pressure set value has a plurality of set values for closing the automatic shutoff valve 11 and sequentially opening it.

The local air storage tank 14 determines the capacity according to the required air amount and the required duration of the load group to which it belongs. Normally, IA compressed air passes through the three-way valve 21, and the low pressure signal of the pressure switch 12 connects the load side and SA.

The local dehumidifier 22 has the ability to bring the required flow rate of the important load system to which it belongs to the same degree of dryness as IA (SA system has a low degree of dryness and adversely affects the instrumentation). The pressure reducing valve 24 is a pressure reducing valve set to have a load pressure slightly lower than the pressure of the IA system, and controls the pressure so as to keep the pressure on the load side constant.

Next, the operation of the embodiment of the present invention will be described. Assuming a case where compressed air is jetted out due to some trouble in the piping or load stretched around like the IA artery, the conventional equipment produces a large amount of jetted air, and the air compressor 1 fully rotates. Further, if the supply cannot catch up even if the backup is received from the SA system, the IA system pressure starts to fall, and when the pressure falls below a certain pressure value, the scrum valve cannot maintain the normal operating state, and the reactor is automatically stopped.

If the jet is an important load of the reactor system, it means that the stable operating conditions of the plant are impaired, and the automatic shutdown of the reactor is unavoidable. If this is avoided, unnecessary stoppage of the plant can be avoided.

Here, a case where the compressed air is ejected from the assumed breakage point in the non-important load group will be described.
If the flow restrictor 13 is provided on the downstream side of the non-important load stop valve 10 of the load group, the ejection amount can be restricted, and I
It is possible to prevent excessive pressure drop in the A system. This effect increases the possibility of preventing unnecessary automatic shutdown of the reactor. This is the self-defense function.

The structure of the flow restrictor 13 is a combination of a flow restricting orifice and a lift type check valve. By providing the flow restrictor 13 with a check valve function, the check valve function works when there is jetting outside the load group to which it belongs and the pressure on the upstream side drops, and the load group that belongs to a healthy one By preventing the compressed air from escaping to the upstream side and combining it with the local air storage tank 14, it has a protective function to maintain the function of the load group to which it belongs for a short time.

The flow restrictor 13 alone is an improvement over the drawbacks of the conventional example, but as the IA system, the plant operation must be continued with jetting, and the following equipment is added. This increases the contribution to stable operation.

A pressure switch 12 is provided on the downstream side of the flow restrictor 13, and the pressure of each load group is monitored. When the pressure falls below a predetermined pressure, the switch operates to close the automatic shutoff valve 11 of the load group, Preventing the leakage or ejection of compressed air can avoid unnecessary shutdown of the reactor unless the load is significant.

It can be said that it is most preferable if the countermeasure can be taken within the range of the load group, but a method of preventing further pressure drop when the loss of compressed air at the assumed breakage point is large and a pressure drop occurs in the entire IA system. Need to take.
In this case, the pressure of the IA system air storage tank 2 is detected, and if the pressure drops, the SA system goes into backup to try to recover the pressure of the IA system. However, if the breakage port is large and the pressure drops suddenly, it will be necessary to take further measures to prevent the reactor from shutting down.

As this method, the pressure header 4 is provided with the main pressure converter 15 to monitor the pressure of the entire IA system. When this pressure falls below the set value, the automatic shutoff valves 11 of all load groups are closed. As a result, the pressure drop stops when the amount of IA used decreases. Then, when the pressure starts to recover, the automatic shutoff valve 11 of the load required group is opened in a preset order according to the importance.

The automatic shutoff valve 11 is controlled by both the pressure switch 12 and the main pressure converter 15. However, when the automatic shutoff valve 11 is opened, both of the automatic shutoff valve 11 closing signals must be cleared. Details of this sequence will be described later.

Local air reservoirs 14 are installed in all load groups. This device contributes to the stable operation of the plant by supplying the stored compressed air to each load for a short time after the automatic shutoff valve 11 is closed.

For an important load, a three-way valve 21 is arranged in the middle of the IA system load pipe, and a pressure reducing valve 24 is passed through one of the valves to allow the SA system compressed air dried by the local dehumidifier 22 to be equal to IA. Connect the equipment. The three-way valve 21 is controlled so that SA is turned on by switching to the SA supply side at the same time when the pressure switch 12 provided in the important load system closes the automatic shutoff valve 11.

According to FIG. 2, the automatic shutoff valve 11 and the pressure switch 12
The control of the main pressure converter 15 and the three-way valve 21 will be described. FIG. 2 shows a theoretical configuration for controlling the automatic shutoff valve 11.
(A) is a logical configuration in which the automatic shutoff valve 11 is automatically closed.
There are two closing signals for the automatic shutoff valve 11. The pressure switch low signal 26 indicated by PS1 indicating low to PS4 indicating low output from the pressure switch 12 or the main pressure converter low signal 25 indicating by PT indicating low output from the main pressure converter 15 enters and exits the decision circuit OR logic 27. .

One of the low-pressure signals input to the judgment circuit OR logic 27 outputs the shut-off valve closing signals 28 of NO1 to NO4 to close the automatic shut-off valve 11. The pressure set point is set so that the pressure switch low signal 26 is higher than the main pressure transducer low signal 25, and the interruption of the load group in question precedes the interruption of the full load, limiting the effect. For important loads, the pressure switch low signal 26 output from the pressure switch 12 causes the three-way valve 21 to switch from IA to SA for the load side (three-way valve switching (important load)).

FIG. 2B shows a logical configuration for automatically opening the automatic shutoff valve 11. PS when opening the automatic shutoff valve 11
1 to PS4 pressure switch normal signal 32 and P indicating normal indication
When the two main pressure converter normal signals 30 indicating normal T indication enter the judgment circuit AND logic 33, the AND logic circuit outputs the signals of the shutoff valve open NO 1 to shutoff valve open 34 to output the automatic shutoff valve 11 To open. The main pressure transducer normal signal 30 is emitted from the main pressure transducer 15 when the pressure header 4 returns to the set value. The main pressure converter normal signal 30 has a plurality of set values, and each set value is determined for each load group by classifying the importance of the load in advance.

The main pressure converter 15 inputs the pressure value to the sequence controller 31. The sequence controller 31 classifies the importance of loads in advance and determines the order in which they are used.The main pressure converter normal signal corresponding to each load group is determined according to the pressure value.
Send 30 values to the corresponding load group. Each load group has an automatic shutoff valve when the two signals of the pressure switch normal signal 32 and the main pressure converter normal signal 30 to which it belongs are aligned.
Open 11

Therefore, in the load group having the assumed breakage point, since the pressure switch normal signal 32 is not input, the automatic shutoff valve 11 is not opened and the plant operation can be continued with the defective point being isolated. Further, for an important load, the pressure switch normal signal 32 causes the three-way valve 21 to switch from SA to IA for the load [three-way valve switching back (important load) 35].

FIG. 3 shows an automatic shutoff valve belonging to each load group.
Fig. 11 shows the relationship between pressure and time when opening 11. Pressure on the vertical axis,
The horizontal axis represents time. After the automatic shutoff valves 11 of all load groups are closed by the action of the main pressure converter 15, when the pressure gradually recovers, the pressure of the main pressure converter 15 rises according to the pressure curve shown in FIG. Go. The NO1 normal pressure a signal is issued at the time of NO1 shutoff valve open signal generation f on the time axis. At this stage, one of the two conditions for opening the automatic shutoff valve 11 of the NO1 load group is satisfied.

Separately from this, if the indicated value of the pressure switch 12 of the NO1 load group is equal to or higher than the pressure at which the automatic shutoff valve 11 is closed, the assumed breakage point 21 satisfies another condition for opening the automatic shutoff valve 11. It will be. When these two conditions are met, a signal for opening the automatic shutoff valve 11 is issued from the decision circuit AND logic 33, and the automatic shutoff valve 11 of the NO1 load group is actually opened.

As soon as the conditions of NO2 and NO3 are met, the automatic shutoff valve 11 opens, and normal recovery can be achieved except for the assumed breakage point. Importance of the load to which the assumed fracture point belongs,
After-the-fact policies will be determined in consideration of the time required for recovery and the impact.

Next, the order of importance of load will be described. According to the importance of this load, recovery from self-isolation of the IA system is measured to ensure stable operation of the plant. First order ・ CRD, HCU system (scrum system, scrum related valve) This system automatically shuts down the reactor if there is a break in its own group, and automatically shuts down if the pressure drops in other breaks. It is the most important load.

Main Steam (MS) System (MSIV) This system has a low possibility of shutting down rapidly and automatically shutting down the reactor because it has its own air storage tank if there is a break in its own group. This is one of the most important loads because the reactor automatically shuts down when the pressure drops.

Second order ・ Air conditioning system (reactor building, turbine building, R / W building ventilation system sluice valve), reactor auxiliary cooling (RCW) system (emergency shutoff valve) This system broke within its own group If there is, it is an important load that limits the operation of the plant because it cuts off the cooling water of the load that requires cooling water during normal operation of the plant.

Third-rank Reactor Recirculation (PLR) system (M
G set oil cooler temperature control valve), Reactor coolant purification (CUW) system (non-regenerative heat exchanger / temperature control valve), RCW
The system (heat exchanger / temperature control valve) is an air-consuming load and loses its function in a short time. Both systems are essential for stable plant operation. Quick recovery is needed. The load of this group is backed up by a large air storage tank or compressed air in the in-house air system.

4th rank ・ Other reactor system load, turbine system load, R / W system load These have a great influence when the IA system is lost, but loads that cause the plant to stop immediately or automatically stop. is not. 3rd important load
Up to the rank, and the fourth rank is the non-important load.

[0058]

According to the present invention, the air pressure applied to the HCU scrum valve is reduced in the event of a trouble such as the injection of compressed air in the IA system piping or the load, and the scram valve is opened to automatically remove unnecessary reactors. The possibility of suspension can be avoided by providing accident protection capability and self-isolation function. As a result, the reliability is improved and it contributes greatly to the stable operation of the plant.

[Brief description of the drawings]

FIG. 1 is a system diagram showing an embodiment of a compressed air supply device for instrumentation according to the present invention.

2 is a block diagram showing a logical configuration for controlling the automatic shutoff valve in FIG. 1, (a) showing a logical configuration for automatically closing the automatic shutoff valve, and (b) showing a logical configuration for automatically opening the automatic shutoff valve. Block Diagram.

FIG. 3 is an IA for automatically opening an automatic shutoff valve in FIG.
The pressure curve figure which shows the relationship between system pressure and time.

[Explanation of symbols]

1 ... Air compressor, 2 ... Air storage tank, 3 ... Air dehumidifier, 4 ...
Pressure header, 5 ... Reactor system pressure header, 6 ... R / W
System pressure header, 7 ... Turbine system pressure header, 8 ... Header stop valve, 9 ... Reactor system important stop valve, 10 ... Unimportant stop valve,
11 ... Automatic shutoff valve, 12 ... Pressure switch, 13 ... Flow restrictor,
14 ... Local air storage tank, 15 ... Main pressure converter, 16 ... Reactor system important load, 17 ... Reactor system non-important load, 18 ... R / W system non-important load, 19 ... Turbine system non-important load, 20 ... HCU scrum valve load, 21 ... 3-way valve, 22 ... Local dehumidifier, 23 ... Local compressed air system, 24 ... Pressure reducing valve, 25 ... Main pressure transducer low signal, 26 ... Pressure switch low signal, 27 ... Judgment circuit OR Logic, 28 ... Automatic shutoff valve closing signal, 29 ... Three-way valve switching signal, 30 ... Main pressure converter normal signal, 31 ... Sequence controller control signal, 32 ... Pressure switch normal signal, 33 ... Judgment circuit AND logic, 34 ... Automatic shut-off valve open signal, 35 ... 3-way valve switching return signal, a ... Main pressure transducer normal pressure, b ... PS1 normal pressure, c ... PS2 normal pressure, d
... PS3 normal pressure, e ... PS4 normal pressure, f ... PT normal instruction, g ... NO1 shutoff valve open, h ... NO2 shutoff valve open, i ...
NO3 shutoff valve open, j ... NO4 shutoff valve open.

Claims (3)

[Claims] 1. An instrument comprising a combination of an air compressor, an air storage tank, an air dehumidifier, a pressure header, an air pipe and valves, which requires compressed air in a nuclear power plant, a regulating valve and an air actuated valve. In a compressed air supply facility for instrumentation of a nuclear power plant that supplies compressed air to a main pressure converter provided in the pressure header, an automatic shutoff valve, a pressure switch and a local air storage tank are provided in the air pipe downstream from the pressure header. A compressed air supply facility for instrumentation of a nuclear power plant, which is characterized by being provided. 2. The compressed air supply for instrumentation of a power plant according to claim 1, further comprising a flow restrictor provided between the downstream side of the automatic shutoff valve and the pressure switch and the local air storage tank. Facility. 3. A three-way valve is connected to the downstream side of the flow restrictor, and a local dehumidifier and a pressure reducing valve are connected to a connection port on the side opposite to the downstream load side of the three-way valve. 1. Compressed air supply equipment for instrumentation of a power plant according to 1.