Experimental device for nuclear reactor water replenishing boric acid mixing ratio concentration deviation

Abstract

The invention belongs to the technical field of nuclear industry measurement, and aims to solve the problem that the existing AP series third-generation nuclear power replenishment water boron concentration is not accurate to influence the safety operation hidden danger of a reactor. The invention provides a nuclear reactor water replenishing boric acid mixing ratio concentration deviation experimental device which is provided with a water tank, one outlet end of the water tank is sequentially connected with a variable frequency pump, a surge tank, a first flowmeter, a three-way valve, a water replenishing pump and a second flowmeter, and the second flowmeter is connected with the water tank to form a loop; the other outlet end of the water tank is sequentially connected with a high-pressure pump, a third flowmeter and a three-way valve. The measurement of the boric acid proportioning concentration can be realized, the flow characteristics of related valves in a boric acid proportioning system can be further verified, and the design reliability of the related valves is guaranteed.

Description

Technical Field

[0001] The present application belongs to the field of nuclear industry measurement technology, and in particular relates to a nuclear reactor water replenishment boric acid mixture ratio concentration deviation experimental device. Background Art

[0002] The boric acid proportioning loop is an important part of the chemical and volume control system, which directly affects the core reactivity control and the pressurizer liquid level control. The main function of this loop is to mix desalted water and boric acid (2.5%) according to the setting to make a boric acid solution with a target concentration of 0ppm~4375mm to supplement boric water to the primary loop, core water supply tank, injection tank and spent pool. Compared with the second-generation improved unit (M310), the boric acid proportioning system of the third-generation unit (AP1000) is simple in structure, mainly consisting of water supply pump, pneumatic three-way valve, desalted water pressure reducing valve, boric acid storage tank and other equipment.

[0003] Since the commissioning of the boric acid proportioning circuit of the third-generation nuclear electrochemical and volumetric control system began in 2016, in manual mixing mode and automatic water replenishment mode, the boric acid solution concentration often deviates too much from the target value, triggering the boron deviation alarm, and even causing the water replenishment operation to terminate. The main control room has issued status reports many times, reporting that the boric acid proportioning circuit is prone to triggering the boron deviation alarm. The third-generation nuclear power unit has included this problem in the list of top ten problems, organized personnel to analyze and test it many times, and optimized the instrumentation logic and parameter settings, but the problem has not been completely solved. Summary of the invention

[0004] The purpose of the present application is to provide a nuclear reactor water make-up boric acid mixture ratio concentration deviation experimental device to solve the problem that the current AP series third-generation nuclear power water make-up boron concentration is inaccurate and affects the safe operation of the reactor.

[0005] In order to achieve the above objectives, this application provides the following technical solutions:

[0006] The present application provides a nuclear reactor water replenishment boric acid mixed ratio concentration deviation experimental device, which has a water tank, one outlet end of the water tank is connected in sequence to a frequency conversion pump, a pressure regulating tank, a first flow meter, a three-way valve, a water replenishment pump, and a second flow meter, and the second flow meter is connected to the water tank to form a loop; the other outlet end of the water tank is connected in sequence to a high-pressure pump, a third flow meter and the three-way valve.

[0007] In some embodiments, a pressure reducing valve is provided between the high-pressure pump and the third flow meter.

[0008] In some embodiments, a fourth pipeline is connected to the third pipeline between the high-pressure pump and the pressure reducing valve, the fourth pipeline is connected to the water tank, and a return water regulating valve is provided on the fourth pipeline.

[0009] In some embodiments, a fourth pressure transmitter is provided on the third pipeline.

[0010] In some embodiments, a first pressure transmitter is provided on the second pipeline connecting the first flow meter and the three-way valve.

[0011] In some embodiments, a second pressure transmitter is provided between the three-way valve and the water supply pump.

[0012] In some embodiments, a third pressure transmitter is provided between the third flow meter and the three-way valve.

[0013] In some embodiments, an isolation valve and a check valve are provided between the pressure stabilizing tank and the first flow meter.

[0014] In some embodiments, bypass valves are connected in parallel to both ends of the inlet and outlet of the water replenishment pump.

[0015] In some embodiments, one of the outlet ends of the water tank is connected to a sixth pipeline, and a drain valve is provided on the sixth pipeline; one of the inlet ends of the water tank is connected to a seventh pipeline, and an exhaust valve is provided on the seventh pipeline; one of the inlet ends of the water tank is connected to an eighth pipeline, and a water replenishment isolation valve is provided on the eighth pipeline.

[0016] Compared with the prior art, the nuclear reactor water replenishment boric acid mixed ratio concentration deviation experimental device provided by the present application has the following beneficial effects:

[0017] This application can realize the measurement of boric acid ratio concentration, and can further verify the flow characteristics of related valves in the boric acid ratio system to ensure the reliability of the related valve design.

[0018] This application can conduct simulation tests on valves, instruments and control systems for regulating the boric acid ratio concentration to verify whether the designed ratio response time, ratio accuracy and stability can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solution of the present application, the following is a brief introduction to the drawings required for the technical description.

[0020] Figure 1 This is a schematic diagram of the structure of the nuclear reactor water replenishment boric acid mixture ratio concentration deviation experimental device provided in this application.

[0021] Description of reference numerals:

[0022] 1: Water tank; 2: Water supply isolation valve; 3: Exhaust valve; 4: Steam trap; 5: Liquid level gauge; 6: Isolation valve; 7: Frequency conversion pump; 8: Pressure gauge; 9: Pressure regulating tank; 10: Isolation valve; 11: Check valve; 12: First flow meter; 13: First pressure transmitter; 14: Isolation valve; 15: High-pressure pump; 16: Return water regulating valve; 17: Fourth pressure transmitter; 18: Pressure reducing valve; 19: Third flow meter; 20: Check valve; 21: Third pressure transmitter; 22: Three-way valve; 23: Second pressure transmitter; 24: Isolation valve; 25: Bypass valve; 26: Water supply pump; 27: Outlet flow regulating valve; 28: Second flow meter; 29: Controller. DETAILED DESCRIPTION

[0023] The following is further explained in detail through specific implementation methods.

[0024] This application conducts experimental research on various factors that affect concentration deviation, tests the mixing conditions between the water replenishment pressure reducing valve, the pneumatic three-way valve and the concentrated boric acid solution, and finds that the root cause of the deviation of the boric acid concentration ratio is the combination of the following three factors: insufficient adjustment accuracy of the three-way valve, insufficient flow capacity and pressure regulation accuracy of the pressure reducing valve, and insufficient instrument accuracy of the flow meter. Through the above cause analysis and targeted treatment, a nuclear reactor water replenishment boric acid mixed ratio concentration deviation experimental device is provided, which is suitable for the simulated working condition test of the boric acid ratio circuit of the chemical and volume control system of the nuclear power plant, and is mainly used to test the adjustment ability of the three-way valve in the boric acid ratio circuit to the boric acid ratio concentration.

[0025] The device includes a boric acid pipeline pressure stabilizing unit, a desalted water pipeline pressure stabilizing unit, a water return unit, a pressure reducing valve and three-way valve installation pipeline, and a DCS control system.

[0026] The boric acid pipeline pressure stabilizing unit provides a stable water source for the boric acid side of the three-way valve in the test device, and automatically ensures that the upstream pressure of the boric acid side of the three-way valve is stable and constant through the pressure stabilizing tank, meeting the upstream pressure condition of the boric acid side of the three-way valve in the boric acid proportioning circuit.

[0027] The desalted water pipeline pressure stabilizing unit provides a stable water source for the desalted water side of the three-way valve in the test device, and ensures that the upstream pressure on the desalted water side of the three-way valve is stable and constant through the desalted water pipeline pressure reducing valve, meeting the upstream pressure condition of the desalted water side of the three-way valve in the boric acid proportioning circuit.

[0028] The return water unit is mainly composed of a water supply pump and a three-way valve outlet flow regulating valve, which is used to control the pipeline flow to meet system requirements.

[0029] The installation pipeline of the pressure reducing valve and three-way valve is mainly composed of the pressure reducing valve and three-way valve body, the upstream pressure changer of the pressure reducing valve, the downstream pressure transmitter of the pressure reducing valve, the pressure transmitter on the boric acid side of the three-way valve, the pressure transmitter on the boric water side of the three-way valve, the flow transmitter on the boric acid side of the three-way valve, the flow transmitter on the desalted water side of the three-way valve, and the flow changer on the boric water side of the three-way valve.

[0030] The test signal of the test device is output, collected and processed by the DCS control system. The signal collector can simultaneously collect the flow transmitter, pressure transmitter, differential pressure transmitter, temperature transmitter, control valve control signal output, valve position feedback signal, and display the collected data in the computer, and can be fitted into a curve in the computer for data analysis. The concentration ratio test process is automatically adjusted by the DCS system.

[0031] The test signal of the test device is output, collected and processed by the DCS control system. The signal collector can simultaneously collect the flow transmitter, pressure transmitter, control valve control signal output, valve position feedback signal, and display the collected data in the computer, and can be fitted into a curve in the computer for data analysis. The concentration ratio test process is automatically adjusted by the DCS system.

[0032] Example

[0033] like Figure 1 As shown, the boric acid pipeline voltage stabilizing unit includes a variable frequency pump 7 and a voltage stabilizing tank 9 connected by the pipeline. The voltage stabilizing tank 9 is also provided with a pressure gauge 8 for monitoring the pressure inside the voltage stabilizing tube. An isolation valve 6 is also provided between the variable frequency pump 7 and the water tank 1 for isolating and repairing the variable frequency pump 7. One outlet end of the water tank 1 is connected to the variable frequency pump 7, and the water tank 1, the isolation valve 6, and the variable frequency pump 7 are connected through a first pipeline. The water tank 1 provides sufficient water source, and the variable frequency pump 7 performs pressurized water pumping. The pressure on the boric acid side of the three-way valve 22 is stabilized at the required operating value through the voltage stabilizing tank 9 downstream of the variable frequency pump 7.

[0034] An isolation valve 10 and a check valve 11 are connected downstream of the pressure stabilizing tank 9 for system isolation and maintenance and to prevent backflow of boric acid. A first flow meter 12 is connected downstream of the check valve 11, and the first flow meter 12 is connected to a three-way valve 22. A first pressure transmitter 13 is provided on the second pipeline connecting the first flow meter 12 and the three-way valve 22 for measuring the inlet pressure value on the boric acid side of the three-way valve 22.

[0035] It should be noted that the dotted line between the first pressure transmitter 13 and the second pressure transmitter 23 represents the association of signals, and the value of the first pressure transmitter 13 will affect the value of the second pressure transmitter 23; the dotted line between the third pressure transmitter 21 and the second pressure transmitter 23 represents the association of signals, and the value of the third pressure transmitter 21 will affect the value of the second pressure transmitter 23; the dotted line between the first flow meter 12, the third flow meter 19, the controller 29, and the three-way valve 22 represents the association of signals, and the system collects the flow signals of the first flow meter 12 and the third flow meter 19, and outputs a control signal to the three-way valve 22 through logical operations of the controller 29.

[0036] The other outlet end of the water tank 1 is connected to the high-pressure pump 15, and an isolation valve 14 is provided between the water tank 1 and the high-pressure pump 15 for isolating and repairing the high-pressure pump 15. The outlet pipeline (third pipeline) of the high-pressure pump 15 is connected to a pressure reducing valve 18, and a loop (fourth pipeline) is also connected to the outlet pipeline, and the loop is connected to the water tank 1, and a return water regulating valve 16 is provided on the loop.

[0037] Optionally, a fourth pressure transmitter 17 is further provided on the outlet pipeline for monitoring the inlet pressure of the pressure reducing valve 18 .

[0038] A third flow meter 19 is connected downstream of the pressure reducing valve 18 to measure the flow rate of the desalted water pipeline. The third flow meter 19 is connected to the three-way valve 22 through a fifth pipeline, and a check valve 20 is provided on the fifth pipeline to prevent the desalted water from flowing back. A third pressure transmitter 21 is also provided on the fifth pipeline to measure the inlet pressure value of the desalted water side of the three-way valve 22.

[0039] The water tank 1 provides sufficient water source, and the water is pressurized and pumped by the high-pressure pump 15. First, the outlet pressure of the high-pressure pump 15 is adjusted by the return water regulating valve 16 downstream of the high-pressure pump 15, and the outlet pressure of the high-pressure pump 15 is adjusted to the operating value required by the pressure reducing valve 18. Then, the pressure on the desalted water side of the three-way valve 22 is stabilized at the required operating value through the pressure reducing valve 18.

[0040] The boric acid water at the outlet of the three-way valve 22 is pumped out by the water supply pump 26, and the flow value of the return water unit is adjusted by the outlet flow regulating valve 27 after the water supply pump 26. A second pressure transmitter 23 is also provided between the three-way valve 22 and the water supply pump 26, which is used to measure the inlet pressure value of the boric acid side of the three-way valve 22.

[0041] Optionally, an isolation valve 24 is further provided between the second pressure transmitter 23 and the water supply pump 26 for isolating and overhauling the water supply pump 26 .

[0042] Optionally, a bypass valve 25 is connected in parallel to both ends of the inlet and outlet of the water supply pump 26 to verify whether the boric acid ratio accuracy and speed can reach the design index when the water supply pump 26 is not used.

[0043] The outlet pipeline of the water supply pump 26 is connected to the water tank 1 , and an outlet flow regulating valve 27 and a second flow meter 28 are sequentially arranged on the outlet pipeline for measuring the flow value on the boron water side of the three-way valve 22 .

[0044] The pressure reducing valve and three-way valve installation pipeline mainly include the three-way valve 22, the pressure reducing valve 18 and various measuring instruments. The measuring instruments include the fourth pressure transmitter 17 behind the high-pressure pump 15, which is used to measure the valve front pressure of the pressure reducing valve 18, the third flowmeter 19 behind the pressure reducing valve 18, which is used to measure the flow of the desalted water pipeline, the pressure transmitter 21 on the desalted water side of the three-way valve 22, which is used to measure the inlet pressure value of the desalted water side of the three-way valve 22, the flowmeter 12 behind the pressure regulating tank 9, which is used to measure the flow of the boric acid pipeline, the first pressure transmitter 13 on the boric acid side of the three-way valve 22, which is used to measure the inlet pressure value of the boric acid side of the three-way valve 22, the second pressure transmitter 23 on the boric water side of the three-way valve 22, which is used to measure the outlet pressure value of the boric water side of the three-way valve 22, and the flowmeter 28 behind the water supply pump 26, which is used to measure the flow value of the boric water side of the three-way valve 22.

[0045] The controller 29 is used to collect the flow signals of the first flow meter 12 and the third flow meter 19, perform logical operations through the controller 29, output control signals to the three-way valve 22, and is also used to monitor the various pressure signals on the system, the parameters of the second flow meter 28, the outlet flow regulating valve 27, and the three-way valve 22. It can also control the start and stop of the three pumps in the system, the opening of the outlet flow regulating valve 27, and the opening of the three-way valve 22. 29 is a DCS control system, which is connected to all the pressure transmitters, flow meters, three-way valves, outlet flow regulating valves, and control lines of the three pumps in the system.

[0046] Optionally, a liquid level meter 5 is further provided on the water tank 1 for monitoring the liquid level of the water tank 1 .

[0047] Optionally, the other outlet end of the water tank 1 is also connected to a drain valve 4 through a sixth pipeline for draining water from the water tank 1 .

[0048] Optionally, one of the inlet ends of the water tank 1 is connected to a seventh pipeline, and the seventh pipeline is provided with an exhaust valve 3 for exhausting the water tank 1 .

[0049] Optionally, one of the inlet ends of the water tank 1 is connected to an eighth pipeline, and the eighth pipeline is provided with a water replenishment isolation valve 2 for replenishing water in the water tank 1 .

[0050] Therefore, this device is designed in detail in terms of the boric acid pipeline pressure stabilizing unit, the desalted water pipeline pressure stabilizing unit, the return water unit, etc. based on the simulated operating conditions of the boric acid proportioning loop of the chemical and volumetric control system of the nuclear power plant, ensuring the maximum applicability of the entire device to the simulated operating conditions test of the boric acid proportioning loop of the chemical and volumetric control system.

[0051] The specific operation process of the device test is as follows:

[0052] Step 1, start the simulated desalted water pipeline high pressure pump 15;

[0053] Step 2, start the simulated boric acid pipeline variable frequency pump 7;

[0054] Step 3: Determine that the initial state of the three-way valve 22 is fully closed;

[0055] Step 4: Adjust the pressure of the desalted water pressure reducing valve 18 to the set pressure value;

[0056] Step 5: Start the water supply pump 26;

[0057] Step 6: Input the required water replenishment flow value to the outlet flow regulating valve 27 to start automatic adjustment and control;

[0058] Step 7: Input the set boron concentration value into the replenishing water, and start the three-way valve 22 to automatically mix;

[0059] Step 8: The DCS system automatically records the mixing time and automatically alarms after exceeding the specified 2 minutes.

[0060] The test device designed by the present invention can simulate the actual operating conditions of the boric acid proportioning loop of the nuclear power plant chemical and volume control system, and can provide effective data for the cause analysis and solution of the boric acid proportioning delay problem. The device can simulate the boric acid proportioning concentration, verify whether the flow rate and pressure affect the pressure relief stability of the pressure reducing valve and the regulating stability and reliable operation of the three-way valve, and the test bench can also be used for the actual flow verification of the flow characteristics of other types of regulating valves (such as regulating valves with actuators, manual regulating valves, etc.).

[0061] The above description is only a specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed in the present application should be covered within the protection scope of the present application.

Claims

1. A nuclear reactor water replenishment boric acid mixed ratio concentration deviation experimental device, characterized in that: A water tank (1) is provided, wherein one outlet end of the water tank (1) is sequentially connected to a variable frequency pump (7), a pressure regulating tank (9), a first flow meter (12), a three-way valve (22), a water supply pump (26), and a second flow meter (28), and the second flow meter (28) is connected to the water tank (1); and the other outlet end of the water tank (1) is sequentially connected to a high-pressure pump (15), a third flow meter (19), and the three-way valve (22).

2. The nuclear reactor water replenishment boric acid mixed ratio concentration deviation experimental device according to claim 1, characterized in that: A pressure reducing valve (18) is provided between the high-pressure pump (15) and the third flow meter (19).

3. The nuclear reactor water replenishment boric acid mixed ratio concentration deviation experimental device according to claim 2, characterized in that: A fourth pipeline is connected to the third pipeline between the high-pressure pump (15) and the pressure reducing valve (18), the fourth pipeline is connected to the water tank (1), and a return water regulating valve (16) is provided on the fourth pipeline.

4. The nuclear reactor water replenishment boric acid mixed ratio concentration deviation experimental device according to claim 3, characterized in that: The third pipeline is provided with a fourth pressure transmitter (17).

5. The nuclear reactor water replenishment boric acid mixed ratio concentration deviation experimental device according to claim 1, characterized in that: A first pressure transmitter (13) is provided on the second pipeline connected to the first flow meter (12) and the three-way valve (22).

6. The nuclear reactor water replenishment boric acid mixed ratio concentration deviation experimental device according to claim 1, characterized in that: A second pressure transmitter (23) is provided between the three-way valve (22) and the water replenishment pump (26).

7. The nuclear reactor water replenishment boric acid mixed ratio concentration deviation experimental device according to claim 1, characterized in that: A third pressure transmitter (21) is provided between the third flow meter (19) and the three-way valve (22).

8. The nuclear reactor water replenishment boric acid mixed ratio concentration deviation experimental device according to claim 1, characterized in that: An isolation valve (10) and a check valve (11) are provided between the pressure stabilizing tank (9) and the first flow meter (12).

9. The nuclear reactor water replenishment boric acid mixed ratio concentration deviation experimental device according to claim 1, characterized in that: Bypass valves (25) are connected in parallel at both ends of the inlet and outlet of the water replenishment pump (26).

10. The nuclear reactor water replenishment boric acid mixed ratio concentration deviation experimental device according to claim 1, characterized in that: One of the outlet ends of the water tank (1) is connected to a sixth pipeline, on which a drain valve (4) is provided; one of the inlet ends of the water tank (1) is connected to a seventh pipeline, on which a gas exhaust valve (3) is provided; and one of the inlet ends of the water tank (1) is connected to an eighth pipeline, on which a water supply isolation valve (2) is provided.

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