Method and device for checking non-drainage pressure of a pilot safety valve of a nuclear power plant

Abstract

This invention belongs to the technical field of pilot-operated safety valve calibration and maintenance in nuclear power plants, specifically relating to a method and apparatus for calibrating the non-drainage pressure of a pilot-operated safety valve in a nuclear power plant. The method includes the following steps: apparatus assembly; tooling connection; adjustment and clamping of the control cabinet rod head by the three-piece block jaws; connection of the drain pipeline to a pressure source; connection of the pressure sensor to the valve head needle valve; opening the water filling valve connected to the pressure source via the drain pipeline, and opening the valve head needle valve to establish pressure; closing the water filling isolation valve; simulating the actual valve opening action; reading the reading F at the corresponding moments of the hydraulic pressure sensor rise and the valve head pressure sensor fall; simulating the actual valve closing action; reading the force sensor reading at the corresponding moment of the valve head pressure sensor fall; step 11: calculating and verifying the force corresponding to the opening and closing setpoints, and outputting the results. Its advantages are: enabling overhauls without low-water levels, reducing maintenance costs, and optimizing the overhaul schedule planning of nuclear power plants.

Description

Technical Field

[0001] This invention belongs to the field of nuclear power plant pilot-operated safety valve calibration and maintenance technology, specifically relating to a method and apparatus for calibrating the non-drainage pressure of a nuclear power plant pilot-operated safety valve. Background Technology

[0002] Existing pilot-operated safety valves used in nuclear power plants have a unique structure, consisting of a complex control cabinet and valve head. Due to this unique structure, they must be completely emptied before calibration. Currently, online calibration of these safety valves is not possible. This necessitates the allocation of dedicated drainage windows for maintenance during refueling and major overhauls at nuclear power plants, impacting the high-performance scheduling of the units.

[0003] Currently, pilot-operated safety valves in nuclear power plants require purging the system pressure lines before disconnecting from the control cabinet. A pressure source is then connected to the control cabinet's system pressure interface, and the system pressure lines are shielded. The pressure is then increased using the pressure source to simulate the setpoint calibration of the pilot-operated safety valve. This design necessitates emptying the system pressure lines before disconnection; without disconnection, setpoint calibration cannot be completed. Summary of the Invention

[0004] The purpose of this invention is to provide a method and apparatus for pressure testing of pilot-operated safety valves in nuclear power plants without venting water, which can solve the problem that pilot-operated safety valves in nuclear power plants cannot be tested online without venting water.

[0005] The technical solution of this invention is as follows: A device for calibrating the non-drainage pressure of a pilot-operated safety valve in a nuclear power plant, comprising a claw mechanism, a force sensor, a signal line, a hydraulic pressure sensor and its pipeline, a hydraulic pump, a hydraulic tensioning device, a valve head pressure sensor, a water filling pressure sensor, a host computer and controller, a water filling pipeline and water source, an isolation valve, a pipeline connection interface of the system where the pilot-operated safety valve is located, a control cabinet piston, a control cabinet spring, a control cabinet push rod head, a three-piece connecting rod, a first isolation valve, a second isolation valve, a drain pipeline, a valve head needle valve, a valve head, and a three-piece block. The valve head is connected to the valve head pressure sensor via a pipeline. A valve head needle valve is connected to the pipeline between the valve head and the valve head pressure sensor. The valve head pressure sensor is connected to the signal line, and the valve head is connected to the... The first isolation valve located on the three-piece block is connected; the water filling pressure sensor is connected to the second isolation valve on the three-piece block through the drain pipe, the water filling pressure sensor is connected to the isolation valve through the pipe, the isolation valve is connected to the water filling pipe and the water source, and the water filling pressure sensor is also connected to the signal line; the system is connected to the first isolation valve located on the three-piece block through the pipe, the system is connected to the control cabinet piston through the pipe, the control cabinet piston is connected to the control cabinet spring, the control cabinet spring is connected to the control cabinet push rod head, the force sensor is connected to the three-piece block connecting rod located on the three-piece block, the force sensor is also connected to the force sensor through the claw mechanism, the force sensor is connected to the host computer and controller through the signal line, the force sensor is connected to the hydraulic tensioning device, and the hydraulic tensioning device is connected to the hydraulic pump through the pipe.

[0006] A method for calibrating the non-draining pressure of a pilot-operated safety valve in a nuclear power plant includes the following steps:

[0007] Step 1: Assembly of the device;

[0008] Step 2: Adjust and clamp the control cabinet rod head using the three-piece tooling connection jaws;

[0009] Step 3: Connect the drain pipe to the pressure source;

[0010] Step 4: Connect a pressure sensor after the needle valve head;

[0011] Step 5: Open the drain pipe connection to the pressure source water filling valve, and open the valve head needle valve to fill water and build up pressure;

[0012] Step 6: Close the water filling isolation valve after the pressure stabilizes;

[0013] Step 7: The hydraulic pump controls the movement of the chuck to complete the downward movement of the control cabinet push rod, simulating the actual opening action of the valve;

[0014] Step 8: Read the reading F at the corresponding moments when the hydraulic pressure sensor rises and the valve head pressure sensor falls. This reading can be converted into the opening setpoint of the safety valve.

[0015] Step 9: The hydraulic pump controls the movement of the chuck to complete the upward movement of the control cabinet push rod, simulating the actual closing action of the valve;

[0016] Step 10: Read the force sensor reading at the moment corresponding to the point where the valve head pressure sensor drops. This reading can be converted into the reseating set value of the safety valve.

[0017] Step 11: Calculate and verify the force corresponding to the opening and closing settings, and output the results.

[0018] Step 1 is as follows:

[0019] The device is assembled, and the hydraulic pump is connected to the hydraulic cylinder through the hydraulic pressure sensor and its pipeline. The end of the hydraulic cylinder is connected to the force sensor and the chuck mechanism through bolts.

[0020] Connect the force sensor, hydraulic pressure sensor, and valve head pressure sensor to the host computer and controller respectively;

[0021] Connect the isolation valve and water pressure sensor to the drain pipe, with the first isolation valve in the open position.

[0022] Step 2 is as follows:

[0023] The hydraulic cylinder is connected to the three-piece block through the bolt holes on the original three-piece block. The chuck mechanism cooperates with the control cabinet push rod head. When the chuck moves downward, it can drive the control cabinet push rod head to move downward.

[0024] Step 3 is as follows:

[0025] Connect the drain line to the pressure source.

[0026] Step 4 is as follows:

[0027] Connect the water filling pipeline and water source to the isolation valve via the pipeline.

[0028] Step 5 is as follows:

[0029] Open the isolation valve to allow the water supply line and water source connected to the drain line to enter the opened second isolation valve through the drain line, and then enter the valve head chamber. Open the valve head needle valve to fill with water and build up pressure.

[0030] Step 6 is as follows:

[0031] When the pressure from the valve head pressure sensor is stable and equal to that from the pressure from the water filling sensor, the water filling isolation valve is closed.

[0032] Step 7 is as follows:

[0033] The hydraulic pump is operated, which drives the control cabinet push rod head to move downward through the hydraulic cylinder, the connected force sensor and the chuck mechanism. The force sensor measures the received force and transmits it to the host computer and controller through the signal line.

[0034] Step 8 is as follows:

[0035] When the control cabinet push rod head moves downward, the control cabinet push rod head is subjected to the elastic force F of the control cabinet spring. 弹 Frictional force F between the piston and the control cabinet 摩 The total force F1 experienced during the downward movement is F 弹 +F 摩

[0036] The formula for calculating the valve's opening setpoint P1 is as follows:

[0037] ,

[0038] Where S is the area of ​​the control cabinet piston.

[0039] Step 9 is as follows:

[0040] The hydraulic pump is operated, which drives the control cabinet push rod head to move upward through the hydraulic cylinder, the connected force sensor and the chuck mechanism. The force sensor measures the received force and transmits it to the host computer and controller through the signal line.

[0041] Step 10 is as follows:

[0042] When the control cabinet push rod head moves upward, it is subjected to the elastic force F of the control cabinet spring. 弹 Frictional force F between the piston and the control cabinet 摩 The total force F2 experienced during the downward movement is F 弹 -F 摩

[0043] The formula for calculating the valve's opening setpoint P2 is as follows:

[0044] ,

[0045] Where S is the area of ​​the control cabinet piston.

[0046] Step 11 is as follows:

[0047] The values ​​of F1 and F2 are determined based on the opening and closing times and converted into opening setpoints P1 and P2, respectively. The curves and calculation results are then displayed on the host computer.

[0048] The beneficial effects of this invention are as follows: By providing tensile force through additional tooling, the thrust of the medium is replaced to simulate the pressure rise and fall of the system. Simultaneously, a special device is added to the drain line of the pilot-operated safety valve control cabinet in a nuclear power plant to collect characteristic points of the pilot-operated safety valve's opening and reseating, thereby completing the safety valve's verification. Since the drain line of the pilot-operated safety valve control cabinet is empty, this method can achieve both online and offline verification. Online verification can eliminate the need for low-water-level overhauls, reducing maintenance costs and optimizing the overhaul schedule planning of nuclear power plants. Attached Figure Description

[0049] Figure 1 This is a schematic diagram of a device for calibrating the non-drainage pressure of a pilot-operated safety valve in a nuclear power plant, provided by the present invention.

[0050] Figure 2 A flowchart of a method for calibrating the non-drainage pressure of a pilot-operated safety valve in a nuclear power plant, provided by the present invention.

[0051] Figure 3 This is a schematic diagram of the online calibration setpoint curve for a pilot-operated safety valve.

[0052] In the diagram: 101 Claw mechanism, 102 Force sensor, 103 Signal line, 104 Hydraulic pressure sensor and its pipeline, 105 Hydraulic pump, 106 Hydraulic tensioning device, 107 Valve head pressure sensor, 108 Water filling pressure sensor, 109 Host computer and controller, 110 Water filling pipeline and water source, 111 Isolation valve, 201 Pipeline connection interface of the system where the pilot-operated safety valve is located, 202 Control cabinet piston, 203 Control cabinet spring, 204 Control cabinet push rod head, 205 Three-piece block connecting rod, 206 First isolation valve, 207 Second isolation valve, 208 Drainage pipeline, 209 Valve head needle valve, 210 Valve head, 211 Three-piece block. Detailed Implementation

[0053] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0054] like Figure 1 As shown, a device for calibrating the non-drainage pressure of a pilot-operated safety valve in a nuclear power plant includes a claw mechanism 101, a force sensor 102, a signal line 103, a hydraulic pressure sensor and its pipeline 104, a hydraulic pump 105, a hydraulic tensioning device 106, a valve head pressure sensor 107, a water filling pressure sensor 108, a host computer and controller 109, a water filling pipeline and water source 110, an isolation valve 111, a pipeline connection interface 201 for the system where the pilot-operated safety valve is located, a control cabinet piston 202, and a control cabinet spring. Spring 203, control cabinet push rod head 204, three-piece block connecting rod 205, first isolation valve 206, second isolation valve 207, drain pipe 208, valve head needle valve 209, valve head 210, and three-piece block 211. Valve head 210 is connected to valve head pressure sensor 107 via a pipe. A valve head needle valve 209 is connected to the pipe between valve head 210 and valve head pressure sensor 107. Valve head pressure sensor 107 is connected to signal line 103. Valve head 210 is connected to the three-piece block 211 via a pipe. The first isolation valve 206 on block 211 is connected; the water pressure sensor 108 is connected to the second isolation valve 207 on block 211 via drain pipe 208, the water pressure sensor 108 is connected to isolation valve 111 via pipe, isolation valve 111 is connected to water filling pipe and water source 110, and the water pressure sensor 108 is also connected to signal line 103; system 201 is connected to the first isolation valve 206 on block 211 via pipe, and system 201 is connected to the control cabinet via pipe. The piston 202 is connected to the control cabinet piston 202 and the control cabinet spring 203. The control cabinet spring 203 is connected to the control cabinet push rod head 204. The force sensor 102 is connected to the three-piece block connecting rod 205 located on the three-piece block 211. The force sensor 102 is connected to the claw mechanism 101. The force sensor 102 is connected to the host computer and controller 109 through the signal line 103. The force sensor 102 is connected to the hydraulic tensioning device 106. The hydraulic tensioning device 106 is connected to the hydraulic pump 105 through the pipeline.

[0055] A hydraulic pressure sensor 104 is added to the hydraulic tensioning device 106, and the interface of the hydraulic tensioning device 106 is connected to the bottom of the control cabinet 211. The control cabinet push rod is stretched using the claw mechanism 101, and the claw mechanism 101 transmits the tensile force to the force sensor 102. A water filling interface, an isolation valve 111, and a pressure sensor 108 are added to the drain line 208 at the bottom of the control cabinet.

[0056] A pressure tapping line and a pressure sensor 107 are added after the needle valve 209 that comes with the valve head 210.

[0057] Open the newly added isolation valve 111 on the drain line 208 to fill it with water to about 6 bar, and then close the valve.

[0058] The pressure sensor 107 added to the valve head 210 and the pressure sensor signal, force sensor signal 102 added to the control cabinet, as well as the hydraulic oil pressure sensor, are all introduced into an oscilloscope or display instrument.

[0059] The hydraulic system pulls a push rod downwards, simulating the opening and closing of a safety valve. A force sensor measures the downward pulling force, and a hydraulic sensor measures the fluid pressure as a calibration reference. The hydraulic cylinder returns to its original position after moving a specified distance downwards.

[0060] During the downward movement, when the actuated position moves down to trigger the lower control valve R2 in the control cabinet, the drain outlet water pressure and the valve head pressure become connected, and the signals collected by the newly added pressure sensor in the valve head and the drain pressure sensor in the control cabinet change. Based on the force sensor reading F1 collected at this time, the setpoint P for opening the pilot-operated safety valve in the corresponding system can be calculated. The calculation formula is:

[0061] ,

[0062] Where S1 is the area of ​​the pilot piston of the control cabinet. Let be the frictional force of the mechanism, a constant.

[0063] The product of the hydraulic oil pressure and the area of ​​the hydraulic cylinder at this point can theoretically be divided by F1 to obtain the frictional force and mechanical loss of the hydraulic cylinder mechanism during its downward stroke. At the same time, the F1 reading can be used as a verification in engineering practice.

[0064] During the recovery of the upward movement, when the operating position moves upward to trigger control valve R1 on the control cabinet, the valve head pressure sensor is connected to the system pressure. At this time, the system pressure is 0, meaning the valve head pressure sensor pressure drops to 0. Based on the force sensor reading F2 collected at this time, the closing setpoint P2 for opening the pilot-operated safety valve in the corresponding system can be calculated. The calculation formula is:

[0065] ,

[0066] Where S2 is the area of ​​the pilot piston of the control cabinet. Let be the frictional force of the mechanism, a constant.

[0067] The product of the hydraulic oil pressure and the area of ​​the hydraulic cylinder at this point can theoretically be divided by F2 to obtain the frictional force and mechanical loss of the hydraulic cylinder mechanism during its downward stroke. At the same time, the F2 reading can be used as a verification in engineering practice.

[0068] like Figure 2 As shown, a method for calibrating the non-drainage pressure of a pilot-operated safety valve in a nuclear power plant includes the following steps:

[0069] Step 1: Assembly of the device;

[0070] The device is assembled, and the hydraulic pump 105 is connected to the hydraulic cylinder 106 through the hydraulic pressure sensor 104 and its pipeline. The end of the hydraulic cylinder 106 is connected to the force sensor 102 and the claw mechanism 101 by bolts.

[0071] Connect the force sensor 102, hydraulic pressure sensor 104, and valve head pressure sensor 107 to the host computer and controller 109, respectively.

[0072] The isolation valve 111 and the water pressure sensor 108 are finally connected to the drain pipe 208. The first isolation valve 206 is in the open state.

[0073] Step 2: Adjust and clamp the control cabinet rod head using the three-piece tooling connection jaws;

[0074] The hydraulic cylinder 106 is connected to the three-piece block 211 through the bolt holes on the original three-piece block. The claw mechanism 101 cooperates with the control cabinet push rod head 204. When the claw moves downward, it can drive the control cabinet push rod head 204 to move downward.

[0075] Step 3: Connect the drain pipe to the pressure source;

[0076] Connect the drainage pipe 208 to the pressure source, which in this embodiment is the interface of the plant demineralized water system.

[0077] Step 4: Connect a pressure sensor after the needle valve head;

[0078] Connect the water filling pipeline 110 and the water source to the isolation valve 111 via the pipeline.

[0079] Step 5: Open the drain pipe connection to the pressure source water filling valve, and open the valve head needle valve to fill water and build up pressure;

[0080] Open the isolation valve 111, so that the water filling pipeline connected to the drain pipeline 110 and the water source enter the opened second isolation valve 207 through the drain pipeline 208, and then enter the valve head cavity. Open the valve head needle valve 209 to fill water and build up pressure.

[0081] Step 6: Close the water filling isolation valve after the pressure stabilizes;

[0082] When the pressure of the valve head pressure sensor 107 is stable and equal to that of the pressure of the water filling sensor 108, the water filling isolation valve 111 is closed.

[0083] Step 7: The hydraulic pump controls the movement of the chuck to complete the downward movement of the control cabinet push rod, simulating the actual opening action of the valve.

[0084] The hydraulic pump 105 is operated, which drives the control cabinet push rod head 204 to move downward through the hydraulic cylinder 106, the connected force sensor 102, and the chuck mechanism 101. The force sensor 102 measures the received force and transmits it to the host computer and controller 109 through the signal line 103.

[0085] Step 8: Read the reading F at the corresponding moment when the hydraulic pressure sensor 104 rises and the valve head pressure sensor 107 falls. This reading can be converted into the opening setpoint of the safety valve.

[0086] When the control cabinet push rod head 204 moves downward, the control cabinet push rod head 204 is subjected to the elastic force F of the control cabinet spring 203. 弹 The frictional force F between the piston 202 and the control cabinet 摩 The total force F1 experienced during the downward movement is F 弹 +F 摩

[0087] The formula for calculating the valve's opening setpoint P1 is as follows:

[0088] ,

[0089] Where S is the area of ​​the control cabinet piston 202.

[0090] Step 9: The hydraulic pump controls the movement of the chuck to complete the upward movement of the control cabinet push rod, simulating the actual closing action of the valve;

[0091] The hydraulic pump 105 is operated, which drives the control cabinet push rod head 204 to move upward through the hydraulic cylinder 106, the connected force sensor 102, and the chuck mechanism 101. The force sensor 102 measures the received force and transmits it to the host computer and controller 109 through the signal line 103.

[0092] Step 10: Read the force sensor reading at the moment corresponding to the point of change in the valve head pressure sensor 107. This reading can be converted into the reseating set value of the safety valve.

[0093] When the control cabinet push rod head 204 moves upward, the control cabinet push rod head 204 is subjected to the elastic force F of the control cabinet spring 203. 弹 The frictional force F between the piston 202 and the control cabinet 摩 The total force F2 experienced during the downward movement is F 弹 -F 摩

[0094] The formula for calculating the valve's closing setpoint P2 is as follows:

[0095] ,

[0096] Where S is the area of ​​the piston in control cabinet 202.

[0097] Step 11: Calculate and verify the force corresponding to the opening and closing settings, and output the results.

[0098] according to Figure 3 The values ​​of F1 and F2 are taken at the opening and closing times and converted into opening setpoints P1 and P2, respectively, and then processed in the host computer. Figure 3 The curve is displayed and the calculation results are displayed as constants.

Claims

1. A device for calibrating the non-drainage pressure of a pilot-operated safety valve in a nuclear power plant, characterized in that: The system includes a chuck mechanism, force sensor, signal line, hydraulic pressure sensor and its pipeline, hydraulic pump, hydraulic tensioning device, valve head pressure sensor, water filling pressure sensor, host computer and controller, water filling pipeline and water source, isolation valve, system pipeline connection interface for pilot-operated safety valve, control cabinet piston, control cabinet spring, control cabinet push rod head, three-piece block connecting rod, first isolation valve, second isolation valve, drain pipeline, valve head needle valve, valve head and three-piece block. The valve head is connected to the valve head pressure sensor via a pipeline. A valve head needle valve is connected to the pipeline between the valve head and the valve head pressure sensor. The valve head pressure sensor is connected to the signal line. The valve head is connected to the first isolation valve located on the three-piece block via a pipeline. Connections: The water filling pressure sensor is connected to the second isolation valve on the three-piece block via a drain pipe. The water filling pressure sensor is connected to the isolation valve via a pipe. The isolation valve is connected to the water filling pipe and the water source. The water filling pressure sensor is also connected to a signal line. The system is connected to the first isolation valve on the three-piece block via a pipe. The system is connected to the control cabinet piston via a pipe. The control cabinet piston is connected to the control cabinet spring. The control cabinet spring is connected to the control cabinet push rod head. The force sensor is connected to the three-piece block connecting rod on the three-piece block. The force sensor is connected to the claw mechanism. The force sensor is connected to the host computer and controller via a signal line. The force sensor is connected to the hydraulic tensioning device. The hydraulic tensioning device is connected to the hydraulic pump via a pipe.

2. A method for calibrating the non-drainage pressure of a pilot-operated safety valve in a nuclear power plant using the device described in claim 1, characterized in that, Includes the following steps: Step 1: Assembly of the device; Step 2: Connect the three tooling blocks and adjust the jaw mechanism to clamp the control cabinet rod head; Step 3: Connect the drainage pipe to the water source; Step 4: Connect the valve head pressure sensor after the valve head needle valve; Step 5: Open the drain line connection to the water filling isolation valve, and open the valve head needle valve to fill with water and build up pressure; Step 6: Close the water filling isolation valve after the pressure stabilizes; Step 7: The hydraulic pump controls the movement of the chuck to complete the downward movement of the control cabinet push rod, simulating the actual opening action of the valve; Step 8: Read the pressure sensor readings at the corresponding points of change in the hydraulic pressure sensor (rising) and valve head pressure sensor (falling). These readings can be converted into the safety valve's opening setpoint. Step 9: The hydraulic pump controls the movement of the chuck to complete the upward movement of the control cabinet push rod, simulating the actual closing action of the valve; Step 10: Read the force sensor reading at the moment corresponding to the point where the valve head pressure sensor drops. This reading can be converted into the closing set value of the safety valve. Step 11: Calculate and verify the force corresponding to the opening and closing settings, and output the results.

3. The method for calibrating the non-drainage pressure of a pilot-operated safety valve in a nuclear power plant as described in claim 2, characterized in that... Step 1 is as follows: The device is assembled, and the hydraulic pump is connected to the hydraulic tensioning device through the hydraulic pressure sensor and its pipeline. The end of the hydraulic tensioning device is connected to the force sensor and the chuck mechanism through bolts. Connect the force sensor, hydraulic pressure sensor, and valve head pressure sensor to the host computer and controller respectively; Connect the isolation valve and water pressure sensor to the drain pipe, with the first isolation valve in the open position.

4. The method for calibrating the non-drainage pressure of a pilot-operated safety valve in a nuclear power plant as described in claim 2, characterized in that, Step 2 is as follows: The hydraulic tensioning device is connected to the three blocks through the bolt holes on the original three blocks. The claw mechanism cooperates with the control cabinet push rod head. When the claw moves downward, it can drive the control cabinet push rod head to move downward.

5. The method for calibrating the non-drainage pressure of a pilot-operated safety valve in a nuclear power plant as described in claim 2, characterized in that, Step 3 is as follows: Connect the drain line to the water source.

6. The method for calibrating the non-drainage pressure of a pilot-operated safety valve in a nuclear power plant as described in claim 2, characterized in that, Step 4 is as follows: Connect the water filling pipeline and water source to the isolation valve via the pipeline.

7. The method for calibrating the non-drainage pressure of a pilot-operated safety valve in a nuclear power plant as described in claim 2, characterized in that, Step 5 is as follows: Open the isolation valve to allow the water supply line and water source connected to the drain line to enter the opened second isolation valve through the drain line. When the water enters the valve head chamber, open the valve head needle valve to fill the valve head and build up pressure.

8. The method for calibrating the non-drainage pressure of a pilot-operated safety valve in a nuclear power plant as described in claim 2, characterized in that, Step 6 is as follows: When the pressure from the valve head pressure sensor is stable and equal to the pressure from the water filling pressure sensor, the water filling isolation valve is closed.

9. The method for calibrating the non-drainage pressure of a pilot-operated safety valve in a nuclear power plant as described in claim 2, characterized in that, Step 7 is as follows: The hydraulic pump is operated, which drives the control cabinet push rod head to move downward through the hydraulic cylinder, the connected force sensor and the chuck mechanism. The force sensor measures the force and transmits it to the host computer and controller through the signal line.

10. The method for calibrating the non-drainage pressure of a pilot-operated safety valve in a nuclear power plant as described in claim 2, characterized in that, Step 8 is as follows: When the control cabinet push rod head moves downward, the control cabinet push rod head is subjected to the elastic force F of the control cabinet spring. 弹 Frictional force F between the piston and the control cabinet 摩 The total force F1 experienced by the control cabinet push rod head when it moves downward is F 弹 +F 摩 The formula for calculating the valve's opening setpoint P1 is: ， Where S is the area of ​​the control cabinet piston.

11. The method for calibrating the non-drainage pressure of a pilot-operated safety valve in a nuclear power plant as described in claim 2, characterized in that, Step 9 is as follows: The hydraulic pump is operated, which drives the control cabinet push rod head to move upward through the hydraulic cylinder, the connected force sensor and the chuck mechanism. The force sensor measures the force and transmits it to the host computer and controller through the signal line.

12. The method for calibrating the non-drainage pressure of a pilot-operated safety valve in a nuclear power plant as described in claim 2, characterized in that, Step 10 is as follows: When the control cabinet push rod head moves upward, it is subjected to the elastic force F of the control cabinet spring. 弹 Frictional force F between the piston and the control cabinet 摩 The total force F2 experienced by the control cabinet push rod head when it moves upward is F 弹 -F 摩 The formula for calculating the valve's closing setpoint P2 is as follows: ， Where S is the area of ​​the control cabinet piston.

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