JPH01110295A - Water pressure control unit inspection equipment - 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 [Field of Industrial Application] The present invention relates to an inspection device for a control rod drive system hydraulic control unit (HCU), and in particular, a hydraulic control unit inspection device suitable for inspecting seat leaks of valves in the HCU. Regarding.

[Conventional technology]

In order to control the output of a nuclear reactor, a large number of control rods are arranged in the core of a nuclear reactor, and the lower ends of the control rods are connected to a control rod drive mechanism to insert and withdraw each control rod. . Furthermore, in order to control the drive water supplied to this control rod drive mechanism, an HCU that corresponds one-to-one to the control rod drive mechanism is installed.
An inward control valve unit is provided, to which a drive water line is connected so that water pressure regulated by the control rod drive hydraulic system can be constantly supplied. Then, each directional control valve operates in response to a drive signal from the central control room, supplies the necessary water pressure to the control rod drive mechanism, inserts and withdraws the control rods, and controls the reactor's output. ing.

This is shown in Section 2, which shows an outline of the conventional control rod drive hydraulic system.
This will be explained with reference to the figures. A driving water pump 4 connected to a water source, and a flow rate regulating valve 5 and a pressure regulating valve 6 connected in series on the discharge side of this pump 4 are provided, and the flow rate regulating valve 5 and pressure regulating valve 6 are The drive water line 7 is branched from between. Further, this driving water line 7 is connected to the upstream side of the insertion direction control valve 15 and the withdrawal direction control valve 17 in the direction control valve unit 19 via the check valve 12 . Insertion direction control valve 1
The downstream side of 5 is branched into two parts, one of which is connected to an insertion line 10 that communicates with the lower surface of the piston 3 of the cylinder control rod drive mechanism 2, and the other connected to the upstream side of the extraction and drainage directional control valve 18. Furthermore, the downstream side of the withdrawal direction control valve 17 is also branched into two branches, one of which is connected to the withdrawal line 11 communicating with the upper surface of the piston 3 of the control rod drive mechanism 2, and the other connected to the upstream side of the insertion and drainage direction control valve 16. has been done. The extraction and discharge direction control valve 18 and the insertion and drainage direction control valve 16 are connected in series, and the drainage line 9 is branched from the middle of the stiffener and connected to the downstream side of the pressure regulating valve 6. Further, the downstream side of the pressure regulating valve 6 is connected to an insertion line 10 via a branched cooling water line 8. Insertion direction control valve 15 in direction control valve unit 19. Insertion drainage directional control valve 16. Pull-out direction control valve 17. The extraction and drainage directional control valve 18 is electrically connected to a central control room (not shown).

Next, the operation of moving the control rod in and out will be explained. When the control rod drive mechanism 2 is to perform an insertion operation, the insertion switch is manually turned on by an electric signal from the central control room, and the set timer is activated and the insertion signal is automatically transmitted. Then, the insertion direction control valve 15. The insertion/drainage direction control valve 16 opens, and driving water is injected into the lower surface of the piston 3 of the control rod drive mechanism 2 through the driving water line 7, the insertion direction control valve 15° and the insertion line 10, and pushes the piston 3 up.

Similarly, the water on the top surface of the piston 3 is removed from the drawing line 11. Insertion drainage directional control valve 16. By being discharged through the drainage line 9, the control rod drive mechanism 2 inserts the control rod into the core of the nuclear reactor.

Conversely, if you want the control rod drive mechanism 2 to perform a withdrawal operation, manually turn on the withdrawal switch based on the electric signal in the central control room, and the withdrawal signal will be transmitted to the withdrawal direction control valve 1.
7. The extraction and drainage direction control valve 18 opens, and the driving water flows through the driving water line 7 and the extraction direction control valve 17. The injection acts on the upper surface of the piston 3 of the control rod drive mechanism 2 through the drawing line 11, and pushes the piston 3 down. At the same time, the water on the lower surface of the piston 3 is removed from the insertion line 10. Drainage is carried out through the withdrawal and drainage directional control valve 18 and the drainage line 9, and the control rod drive mechanism 2 withdraws the control rod from the core of the reactor.

In this way, the insertion and withdrawal operations of the control rod drive mechanism 2 are performed by opening the corresponding directional control valves 15, 16 or 17, 18 while the drive signal is being output from the central control room. When the output of the signal is completed, the directional control valves 15, 16 or 17, 18 are closed, and the insertion/extraction operation is completed.

However, at this time, the direction control valves 15, 16 or 1
7. If there is damage or deterioration on the sheet surface of 18, and sheet leakage occurs, the flow of water will not stop even after the output of the drive signal ends, and the drive water will continue to be injected into the control rod drive mechanism 2, causing the control The rod drive mechanism operates continuously in the original direction,
When the amount of driving water is low, it will drift. In particular, if this phenomenon occurs during the withdrawal operation of the control rod drive mechanism 2, the power within the reactor will increase excessively, causing the reactor to come to an emergency shutdown and reducing the operating rate of the plant.

In order to check the health of the directional control valve by installing a detector,
As described in JP-A-60-104287, there is a method of installing a water flow detector in the line that supplies drive water to the HCU; The purpose was to determine whether there was a flow, not to identify a defective directional control valve.

Conventionally, a common method for determining the presence or absence of seat leaks in directional control valves is to remove the directional control valves from the HCU during periodic inspections, and attach them to a leak test device one by one to determine the presence or absence of seat leaks. It was something.

[Problem that the invention seeks to solve]

In the case of a 1100 MWi nuclear power plant, the number of directional control valves is as large as 740. Conventional methods require time and location for removal and installation, number of personnel replacing seal parts, testing and inspection after valve installation, etc.
It required a lot of time and money.

SUMMARY OF THE INVENTION An object of the present invention is to provide a water pressure control unit inspection device that reduces time and costs by attaching a directional control valve to an HCU and performing a leak test.

[Means for solving problems]

The above object is achieved by installing a detector on the outlet side of the directional control valve.

For example, by installing a vibration meter on the outlet side of the directional control valve,
Apply a predetermined water pressure to the inlet side of the valve with the valve closed. After applying water pressure, use a vibration meter to measure the presence or absence of flow. The amount of seat leakage of the valve is determined by measuring the value of the leakage amount using a vibration meter in advance.

[Effect]

In order to detect valve seat leaks, a detector is installed on the outlet side of the directional control valve. Fully close each isolation valve inside the HCU to prevent the test water from flowing out of the HCU. Next, open the test plugs before and after the directional control valve, and close the directional control valve. If a seat leak occurs in the valve when a predetermined water pressure is applied to the inlet side of the directional control valve, it will be displayed on the detector, indicating that there is a leak.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

The control rod drive mechanism 2 (CRD) is provided at the lower part of the nuclear reactor 1, and is composed of a control rod drive water system that switches the flow path of drive water using hydraulic pressure.

This hydraulic system includes a driving water pump 4 connected to a water source, and a flow rate regulating valve 5 on the discharge side of this pump 3. By connecting the pressure regulating valves 6 in series, a drive water regulating section is formed, and the flow regulating valve 5
The drive water line 7 is branched from between the drive water line 7 and the pressure regulating valve 6, and the drive water line 7 is connected to an insertion direction control valve 15 for switching the drive water flow path via a check valve 12. Pull-out drainage direction control valve 16° Pull-out direction control valve 17. The upstream side where the directional control valve unit 19 combined with the pull-out drainage directional control valve 18 merges;
Piping is connected to a control rod drive mechanism 2 connected to the control rods in order to drive the control rods in and out of the core of the nuclear reactor in order to control the core reactivity in the nuclear reactor.

Each directional control valve 15.1 in the directional control valve unit 19
Two G, 17 and 18 are provided in parallel,
The insertion direction control valve 15 and the withdrawal direction control valve 16 are connected in series and are connected on the downstream side of the driving water line 7 or via the check valve 12, and a plug 25 is connected on the downstream side of the check valve 12. is provided. A plug 26 is provided between the insertion direction control valve 16 and the withdrawal and drainage direction control valve 18, which are also connected in series.
A drainage line 9 is branched from between each directional control valve 16, 18 and connected to the downstream side of the pressure regulating valve 6. Furthermore, on the outlet side of each directional control valve 15, 16, 17, and 18, detectors 27 and 28 are installed to detect vibrations caused by the flow.
, 29, 30 will be installed. In addition, a cooling water line 8 branched from the downstream side of the pressure regulating valve 6 is connected between the insertion direction control valve 15 and the withdrawal/drainage direction control valve 1λ which are connected in parallel.
It is connected via a check valve 13 to an insertion line 10 that communicates with the lower surface of the piston 3 of the CRD 2. Further, a withdrawal line 11 is branched from between the withdrawal direction control valve 17 and the insertion/drainage direction control valve 16 which are connected in parallel, and is communicated with the upper surface of the piston 3 of the CRD 2.

To make the CRD 2 perform an insertion operation, turn on the insertion switch using an electric signal in the central control room, the timer will work, and the insertion signal will be automatically transmitted to the insertion direction control valve 15.
．． The insertion and drainage directional control valve 16 opens. Then, the driving water flows through the driving water line 10. Acts on the lower surface of the piston 3 of the CRD 2 via the insertion direction control valve 15 and the insertion line 10,
Push up piston 3. At the same time, the driving water on the upper surface of the piston 3 is drawn out from the drawing line 11. The control rod is inserted after being drained by the drain line 9 via the insertion/drain directional control valve 16.

Conversely, when the CRD 2 is to perform a pulling operation, when the pulling switch is turned on using an electric signal in the central control room, a pulling signal is automatically transmitted to the pulling direction control valve 17. The extraction and drainage directional control valve 18 opens. Then, the driving water flows through the driving water line 8. Acts on the upper surface of the piston 3 of the CRD 2 via the withdrawal direction control valve 17 and the withdrawal line 11,
Push down piston 3. At the same time, the driving water on the lower surface of the piston 3 is transferred to the insertion line 10. The control rod is withdrawn through the withdrawal and drainage directional control valve 18 and drained through the drainage line 9. When finishing such insertion and withdrawal operations, each switch is turned OFF, but the direction control valves 15 and 16 are turned off.
, 17, 18, if a problem such as sheet leakage occurs, the insertion operation that was in progress will be stopped.
Those that were in the process of being pulled out continue to do so. To prevent this problem, regularly check for sheet leakage.

Parts will be replaced, but at that time, the directional control valves 15° and 16
．． Inspect with 17 and 18 attached.

First, each isolation valve 20, 21, 22, 23°24 of HCU
fully close. Next, plug 25. Remove the plug 26,
A pressure pump 31 is connected to the plug 25. Directional control valve 1
6.18 and close the directional control valve 15.17. The pressure is drawn to a predetermined pressure by the pressurizing pump 31, and the directional control valve 15.17
The air inside the directional control valve unit 19 is discharged and water is filled by repeating the opening and closing operations of the directional control valve unit 19. The directional control valves 15 and 17 are closed, the switch of the detector 27 is turned ONL, the amount of vibration of the directional control valve 15 is detected, the switch of the detector 29 is turned ONL, and the amount of vibration of the directional control valve 17 is detected by an oscilloscope. Next, the directional control valve 16.18 is closed, the directional control valve 15.17 is opened, and the air in the directional control valve unit 19 is discharged by repeating the opening and closing of the directional control valve 16.18 in the same manner as described above. next,
The directional control valves 16 and 18 are closed, the detector 28 is turned on, and the amount of vibration of the directional control valve 16 is detected by turning on the switch of the detector 30, and the amount of vibration of the directional control valve 18 is detected by an oscillograph. The amount of vibration detected is compared with the amount of vibration that simulates sheet leakage in advance to determine the amount of leakage. Therefore, the amount of sheet leakage can be measured without removing the 740 directional control valves in a 110 MW power plant.

According to this embodiment, even while the reactor is operating, it is possible to know which directional control valve has a seat leak by turning on the detector of the directional control valve to be operated before normal operation. Although it is impossible to repair the directional control valve during operation,
By isolating the operating function of the HCU from the relevant malfunctioning valve, it is also possible to prevent excessive insertion and withdrawal of the CHD.

〔Effect of the invention〕

According to the present invention, the seat leak test of the directional control valve can be performed during periodic inspection without removing it from the directional control valve unit, which reduces the number of man-hours for periodic inspection, shortens the period of periodic inspection, and improves the quality of seal parts. No need for replacement.

[Brief explanation of the drawing]

FIG. 1 is a piping system diagram of an embodiment of the present invention, and FIG. 2 is a piping system diagram of a conventional technique. DESCRIPTION OF SYMBOLS 1... Nuclear reactor, 2... Control rod drive mechanism, 3... Piston, 4... Driving water pump, 5... Flow rate adjustment valve,
6...Pressure regulating valve.

Claims (1)

[Scope of Claims] 1. In a directional control valve of a water pressure control unit that controls the flow direction of supply and discharge water that drives a control rod drive mechanism of a boiling water reactor, a valve is provided externally on the outlet side of the directional control valve. A water pressure control unit inspection device characterized by being provided with a detector for detecting seat leaks.