Accurate automatic control method for air cavity replacement in nuclear power station voltage stabilizer

Abstract

The invention relates to the field of nuclear power station operation and automatic control, in particular to an accurate automatic control method for air cavity replacement in a nuclear power station voltage stabilizer. The method comprises the following steps: during the starting period of a reactor device, executing an automatic control program, and automatically replacing a nitrogen cavity with a steam cavity in a pressure stabilizer; and during the cooling period of the reactor device, executing an automatic control program, and automatically replacing the steam cavity in the pressure stabilizer with a nitrogen cavity. Full-automatic control over replacement of the air cavity in the pressure stabilizer is achieved, human errors are avoided, the risk is effectively controlled, and the replacement efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the field of nuclear power plant operation and automatic control, and in particular to a precise automatic control method for air cavity replacement in a nuclear power plant pressurizer. Background Art

[0002] During the shutdown of the reactor unit of a pressurized water reactor nuclear power plant, when the primary coolant temperature drops to a certain level and the amount of steam generated in the pressurizer decreases, the buffering capacity of the pressurizer steam space to the primary pressure change decreases, and the primary pressure fluctuation gradually increases, which in turn causes the primary coolant pump inlet pressure fluctuation, endangering its safe operation. In order to avoid the removal of the main pump, non-condensable gas (nitrogen) is provided to the pressurizer to replace the steam cavity with a nitrogen cavity, thereby ensuring the pressure of the gas cavity space in the pressurizer, thereby stabilizing the primary pressure and the main pump inlet pressure.

[0003] During the startup of the reactor unit of a pressurized water reactor nuclear power plant, due to the low initial temperature of the primary circuit, steam cannot be generated. Nitrogen is first filled into the pressurizer to establish a nitrogen chamber, and then the main pump is started to heat the primary circuit. As the temperature of the primary circuit rises, the amount of steam generated in the pressurizer increases, and then the nitrogen in the pressurizer is gradually discharged to form a steam chamber.

[0004] The traditional method of replacing the pressurizer air cavity is manual control. During the replacement, the operator needs to closely monitor key parameters such as the primary circuit pressure and the main coolant pump inlet pressure. The monitoring parameters are many and the task is heavy. In addition, the manual control accuracy is not high. During the replacement, the primary circuit pressure fluctuates greatly, and it needs to be replaced in small quantities and multiple times, which is time-consuming. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a precise automatic control method for air cavity replacement in a nuclear power plant pressurizer, thereby avoiding human errors, effectively controlling risks and improving replacement efficiency.

[0006] The present invention provides a precise automatic control method for replacing the gas cavity in a nuclear power plant pressurizer, comprising: executing an automatic control program during the start-up of a reactor device to automatically replace the nitrogen cavity with a steam cavity in the pressurizer; and executing an automatic control program during the cooling of the reactor device to automatically replace the steam cavity in the pressurizer with a nitrogen cavity;

[0007] During the start-up of the reactor unit, the following steps are specifically included:

[0008] Step S1-1: Automatically monitor the liquid level of the pressurizer and the temperature of the primary circuit main pipeline. If both meet the commissioning standards, automatically send a commissioning permission signal and proceed to the next step;

[0009] Step S1-2: Determine whether the automatic monitoring regulator can discharge nitrogen to the pressure relief tank. If the indicator is met, proceed to the next step;

[0010] Step S1-3: During the process of the pressurizer discharging nitrogen to the pressure relief box, it is automatically monitored and determined whether the nitrogen chamber has been replaced by the steam chamber; if the indicator is reached, the next step is entered;

[0011] Step S1-4: Automatically close the voltage regulator exhaust electric valve, and the system returns to the initial state;

[0012] The cooling of the reactor unit includes the following steps:

[0013] Step S2-1: Automatically monitor and determine that the unit is in a shutdown condition and the nitrogen supply pipeline is available;

[0014] Step S2-2: Automatically monitor and determine whether the pressure stabilizer can discharge steam to the pressure relief tank. If the indicator is met, proceed to the next step;

[0015] Step S2-3: The pressure stabilizer discharges steam to the pressure relief tank, and automatically monitors and determines whether the steam discharge is completed. If the indicator is reached, the next step is entered;

[0016] Step S2-4: issuing an automatic command to pulse open the electric valve of the nitrogen supply pipeline of the regulator;

[0017] Step S2-5: supply nitrogen to the regulator, automatically monitor and determine whether the first nitrogen supply is completed, and if the indicator is reached, proceed to the next step;

[0018] Step S2-6: Automatically monitor and determine whether the steam chamber has been replaced by the nitrogen chamber. If the regulator exhaust electric valve is opened and the specified replacement time is reached and the pressure relief tank pressure increases but the liquid level measured by the pressure relief tank level gauge does not change, then proceed to the next step. If the above conditions are not met, return to step S2-2;

[0019] Step S2-7: Automatically close the regulator exhaust electric valve and the regulator air supply valve to restore the initial state.

[0020] In a specific embodiment of the present invention, in step S1-1, if the liquid level of the pressurizer is greater than 11.1 m and the temperature of the primary circuit main pipeline is less than 150°C, the commissioning standard is met.

[0021] In a specific embodiment of the present invention, in step S1-2, if the pressure of a circuit is greater than 1.9MPa, and the pressure of the pressure relief tank is less than 0.02MPa, and the liquid level of the pressure relief tank is less than 1.8m, the pulse automatically opens the regulator exhaust electric valve and enters the next step.

[0022] In a specific embodiment of the present invention, in step S1-2 and step S1-3, if the pressure of a circuit is less than 1.8M, or the pressure of the pressure relief tank is greater than 0.15M, or the liquid level of the pressure relief tank is greater than 2m, or the stabilizer exhaust electric valve fault alarm is issued, it is automatically determined that the steam chamber replacement is abnormal, and the stabilizer exhaust electric valve is automatically closed.

[0023] In a specific embodiment of the present invention, in step S1-3, when the regulator exhaust electric valve is opened and the specified replacement time is reached and the liquid level of the pressure relief tank increases but the pressure of the pressure relief tank remains unchanged, the indicator is met and the next step is entered.

[0024] In a specific embodiment of the present invention, the step S2-1 is specifically as follows:

[0025] The liquid level of the automatic monitoring regulator is greater than 10.9m, the temperature of the main pipeline of the first circuit is greater than 140℃, the pressure of the pressure relief tank is less than 0.02MPa, and the pressure of the nitrogen supply pipeline is greater than 1.9MPa, allowing the air cavity to be replaced by nitrogen from steam and enter the next step.

[0026] In a specific embodiment of the present invention, in step S2-2,

[0027] If the primary circuit pressure is greater than 1.9MPa, the pressure of the pressure relief tank is less than 0.02MPa, and the liquid level of the pressure relief tank is less than 1.7m, the indicator is met.

[0028] In a specific embodiment of the present invention, in step S2-3,

[0029] If the primary circuit pressure is less than 1.8MPa or the pressure of the pressure relief tank is greater than 0.25MPa or the liquid level of the pressure relief tank is greater than 1.75m, the indicator is met.

[0030] In a specific embodiment of the present invention, in step S2-5: if the pressure of a circuit is greater than 1.9 MPa, the indicator is met.

[0031] In a specific embodiment of the present invention, in steps S2-2 to S2-6, if the pressure of a circuit is less than 1.7MPa or the pressure of the pressure relief tank is greater than 0.25MPa or the liquid level of the pressure relief tank is greater than 1.8m or the stabilizer exhaust electric valve fault alarm or the stabilizer nitrogen supply pipeline electric valve fault alarm is issued, it is automatically monitored and determined as an abnormal air cavity replacement, and the stabilizer exhaust electric valve is automatically closed.

[0032] Compared with the prior art, the precise automatic control method for air cavity replacement in a nuclear power plant pressurizer of the present invention has the following beneficial effects:

[0033] (1) Automatically detect the primary circuit temperature, pressurizer liquid level, pressure relief tank liquid level and pressure, main pump operating status and nitrogen pressure and other parameters to automatically determine whether the unit is in a state where gas cavity replacement can be performed, to avoid unexpected activation of the program causing the unit to enter a transient state;

[0034] (2) Automatically monitor the primary circuit pressure, pressure of the pressure relief box and the liquid level, and then automatically pulse open or pulse close the electric valve for exhausting the gas from the pressure relief box to the pressure relief box. At the same time, it automatically monitors the primary circuit pressure and the nitrogen supply line pressure, and then automatically pulse open or pulse closes the electric valve for supplying nitrogen to the pressure regulator, so as to accurately control the replacement gas flow, effectively reduce the primary circuit pressure fluctuation during the replacement period, shorten the replacement time, improve the replacement efficiency, and ensure the safe operation of the main pump;

[0035] (3) Automatically determine when the air cavity replacement is complete and automatically close the relevant valves to restore the system to its initial state, reducing manual judgment and operation time;

[0036] (4) Automatically monitor the primary circuit pressure, pressure relief tank pressure and liquid level, and electric valve status. When the parameters exceed the limit or the valve is abnormal, the system will be automatically placed in a safe state.

[0037] (5) Automatically monitor relevant parameters, partially relieve the operator of monitoring tasks during unit startup and shutdown, and reduce the risk of human error. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 A schematic diagram showing the structure of the device involved in the replacement of the air cavity in the pressurizer of a nuclear power plant;

[0039] In the figure, 1-pressurizer; 2-primary circuit main pipeline; 3-reactor; 4-primary circuit pressure gauge; 5-pressure relief box; 6-pressure relief box liquid level gauge; 7-pressure relief box pressure gauge; 8-pressurizer exhaust pipeline; 9-pressurizer exhaust electric valve; 10-pressurizer nitrogen supply pipeline; 11-pressurizer nitrogen supply pipeline electric valve; 12-nitrogen supply pipeline pressure gauge; 13-pressurizer liquid level gauge; 14-primary circuit main pipeline thermometer. DETAILED DESCRIPTION

[0040] In order to further understand the present invention, the embodiments of the present invention are described below in conjunction with examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the present invention.

[0041] The precise automatic control method for air cavity replacement in a nuclear power plant pressurizer of the present invention is based on Figure 1 The device shown is implemented.

[0042] The embodiment of the present invention discloses a precise automatic control method for replacing the gas cavity in a nuclear power plant pressurizer, comprising: during the start-up of the reactor device, executing an automatic control program to automatically replace the nitrogen cavity with a steam cavity in the pressurizer; and during the cooling of the reactor device, executing an automatic control program to automatically replace the steam cavity in the pressurizer with a nitrogen cavity;

[0043] During the start-up of the reactor unit, the following steps are specifically included:

[0044] Step S1-1: Automatically monitor the pressurizer liquid level and the primary circuit main pipe temperature. If the pressurizer liquid level is greater than 11.1m and the primary circuit main pipe temperature is less than 150°C, it meets the commissioning standards, and automatically sends a commissioning permission signal to proceed to the next step;

[0045] Step S1-2: Determine whether the automatic monitoring regulator can discharge nitrogen to the pressure relief tank. If the primary circuit pressure is greater than 1.9MPa, the pressure of the pressure relief tank is less than 0.02MPa, and the liquid level of the pressure relief tank is less than 1.8m, the pulse automatically opens the regulator exhaust electric valve and enters the next step;

[0046] Step S1-3: During the process of the pressurizer discharging nitrogen to the pressure relief tank, it is automatically monitored and determined that the nitrogen chamber has been replaced by the steam chamber; when the pressurizer exhaust electric valve is opened and the specified replacement time is reached and the liquid level of the pressure relief tank increases but the pressure of the pressure relief tank remains unchanged, the indicator is met and the next step is entered;

[0047] In the steps S1-2 and S1-3, if the pressure of a circuit is less than 1.8M, or the pressure of the pressure relief tank is greater than 0.15M, or the liquid level of the pressure relief tank is greater than 2m, or the stabilizer exhaust electric valve fault alarm is issued, it is automatically determined that the steam chamber replacement is abnormal, and the stabilizer exhaust electric valve is automatically closed.

[0048] Step S1-4: Automatically close the voltage regulator exhaust electric valve, and the system returns to the initial state;

[0049] The cooling of the reactor unit includes the following steps:

[0050] Step S2-1: Automatically monitor and determine that the unit is in a shutdown condition and the nitrogen supply pipeline is available;

[0051] Specifically:

[0052] Automatically monitor the pressure regulator liquid level greater than 10.9m, the primary circuit main pipeline temperature greater than 140℃, the pressure relief tank pressure less than 0.02MPa, and the nitrogen supply pipeline pressure greater than 1.9MPa, allowing the air cavity to be replaced by steam and nitrogen, and proceed to the next step

[0053] Step S2-2: Automatically monitor and determine whether the pressure stabilizer can discharge steam to the pressure relief tank. If the primary circuit pressure is greater than 1.9MPa and the pressure relief tank pressure is less than 0.02MPa and the pressure relief tank liquid level is less than 1.7m, the indicator is met and the next step is entered;

[0054] Step S2-3: The pressure stabilizer discharges steam to the pressure relief tank, automatically monitors and determines whether the steam discharge is completed. If the primary circuit pressure is less than 1.8MPa or the pressure relief tank pressure is greater than 0.25MPa or the pressure relief tank liquid level is greater than 1.75m, the indicator is met and the next step is entered;

[0055] Step S2-4: issuing an automatic command to pulse open the electric valve of the nitrogen supply pipeline of the regulator;

[0056] Step S2-5: supply nitrogen to the regulator, automatically monitor and determine whether the first nitrogen supply is completed. If the pressure of the first circuit is greater than 1.9 MPa, the indicator is met, and the next step is entered;

[0057] Step S2-6: Automatically monitor and determine whether the steam chamber has been replaced by the nitrogen chamber. If the regulator exhaust electric valve is opened and the specified replacement time is reached and the pressure relief tank pressure increases but the liquid level measured by the pressure relief tank level gauge does not change, then proceed to the next step. If the above conditions are not met, return to step S2-2;

[0058] Step S2-7: Automatically close the regulator exhaust electric valve and the regulator air supply valve to restore the initial state.

[0059] In the steps S2-2 to S2-6, if the pressure of a circuit is less than 1.7MPa or the pressure of the pressure relief tank is greater than 0.25MPa or the liquid level of the pressure relief tank is greater than 1.8m or the stabilizer exhaust electric valve fault alarm or the stabilizer nitrogen supply pipeline electric valve fault alarm is issued, it is automatically monitored and determined as an abnormal air cavity replacement, and the stabilizer exhaust electric valve is automatically closed.

[0060] In summary, the present invention designs and uses an automatic control program for air cavity replacement, which automatically determines whether the unit state allows the air cavity replacement operation to be performed, and has inherent safety;

[0061] Without changing the original design and layout of the system, the system collects parameters in real time and automatically and accurately replaces the gas cavity in the regulator.

[0062] According to the parameters collected in real time, it automatically determines that the air cavity replacement is completed and automatically puts the system back to the initial state;

[0063] According to the real-time collected parameters and electric valve status, it automatically determines whether the parameters are out of limit or the valve is abnormal, and automatically puts the system into a safe state;

[0064] Based on a large number of primary circuit key parameters required for each step, a secondary combination of limits and conditions is performed to accurately determine before, during, after and when the air cavity is replaced.

[0065] Through the technical solution of the present invention, the following technical effects are achieved:

[0066] The replacement operation is automatically performed. During the replacement period, the operator does not need to closely monitor the parameters such as the primary circuit pressure, which reduces the monitoring pressure and avoids human errors.

[0067] Precisely control the primary circuit pressure during cavity replacement, reduce primary circuit pressure fluctuations, and improve replacement efficiency;

[0068] If critical parameters deviate, the replacement operation will be automatically stopped immediately and put into a safe state.

[0069] The above embodiments are only used to help understand the method and core idea of ​​the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0070] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A precise automatic control method for air cavity replacement in a nuclear power plant pressurizer, characterized in that: The method includes executing an automatic control program during the start-up of the reactor device to automatically replace the nitrogen chamber with a steam chamber in the pressurizer; and executing an automatic control program during the cooling of the reactor device to automatically replace the steam chamber in the pressurizer with a nitrogen chamber; During the start-up of the reactor unit, the following steps are specifically included: Step S1-1: Automatically monitor the liquid level of the pressurizer and the temperature of the primary circuit main pipeline. If both meet the commissioning standards, automatically send a commissioning permission signal and proceed to the next step; Step S1-2: Determine whether the automatic monitoring regulator can discharge nitrogen to the pressure relief tank. If the indicator is met, proceed to the next step; Step S1-3: During the process of the pressurizer discharging nitrogen to the pressure relief box, it is automatically monitored and determined whether the nitrogen chamber has been replaced by the steam chamber; if the indicator is reached, the next step is entered; Step S1-4: Automatically close the voltage regulator exhaust electric valve, and the system returns to the initial state; The cooling of the reactor unit includes the following steps: Step S2-1: Automatically monitor and determine that the unit is in a shutdown condition and the nitrogen supply pipeline is available; Step S2-2: Automatically monitor and determine whether the pressure stabilizer can discharge steam to the pressure relief tank. If the indicator is met, proceed to the next step; Step S2-3: The pressure stabilizer discharges steam to the pressure relief tank, and automatically monitors and determines whether the steam discharge is completed. If the indicator is reached, the next step is entered; Step S2-4: issuing an automatic command to pulse open the electric valve of the nitrogen supply pipeline of the regulator; Step S2-5: supply nitrogen to the regulator, automatically monitor and determine whether the first nitrogen supply is completed, and if the indicator is reached, proceed to the next step; Step S2-6: Automatically monitor and determine whether the steam chamber has been replaced by the nitrogen chamber. If the regulator exhaust electric valve is opened and the specified replacement time is reached and the pressure relief tank pressure increases but the liquid level measured by the pressure relief tank level gauge does not change, then proceed to the next step. If the above conditions are not met, return to step S2-2; Step S2-7: Automatically close the regulator exhaust electric valve and the regulator air supply valve to restore the initial state.

2. The precise automatic control method for air cavity replacement in a nuclear power plant pressurizer according to claim 1, characterized in that: In step S1-1, if the liquid level of the pressurizer is greater than 11.1 m and the temperature of the primary circuit main pipeline is less than 150°C, the commissioning standard is met.

3. The precise automatic control method for air cavity replacement in a nuclear power plant pressurizer according to claim 1, characterized in that: In step S1-2, if the pressure of a circuit is greater than 1.9MPa, the pressure of the pressure relief tank is less than 0.02MPa, and the liquid level of the pressure relief tank is less than 1.8m, the pulse automatically opens the regulator exhaust electric valve and enters the next step.

4. The precise automatic control method for air cavity replacement in a nuclear power plant pressurizer according to claim 1, characterized in that: In the steps S1-2 and S1-3, if the pressure of a circuit is less than 1.8M, or the pressure of the pressure relief tank is greater than 0.15M, or the liquid level of the pressure relief tank is greater than 2m, or the stabilizer exhaust electric valve fault alarm is issued, it is automatically determined that the steam chamber replacement is abnormal, and the stabilizer exhaust electric valve is automatically closed.

5. The precise automatic control method for air cavity replacement in a nuclear power plant pressurizer according to claim 1, characterized in that: In step S1-3, when the regulator exhaust electric valve is opened and the specified replacement time is reached and the liquid level of the pressure relief tank increases but the pressure of the pressure relief tank remains unchanged, the indicator is reached and the next step is entered.

6. The precise automatic control method for air cavity replacement in a nuclear power plant pressurizer according to claim 1, characterized in that: The step S2-1 is specifically as follows: The liquid level of the automatic monitoring regulator is greater than 10.9m, the temperature of the main pipeline of the first circuit is greater than 140℃, the pressure of the pressure relief tank is less than 0.02MPa, and the pressure of the nitrogen supply pipeline is greater than 1.9MPa, allowing the air cavity to be replaced by nitrogen from steam and enter the next step.

7. The precise automatic control method for air cavity replacement in a nuclear power plant pressurizer according to claim 1, characterized in that: In the step S2-2, If the primary circuit pressure is greater than 1.9MPa, the pressure of the pressure relief tank is less than 0.02MPa, and the liquid level of the pressure relief tank is less than 1.7m, the indicator is met.

8. The precise automatic control method for air cavity replacement in a nuclear power plant pressurizer according to claim 1, characterized in that: In the step S2-3, If the primary circuit pressure is less than 1.8MPa or the pressure of the pressure relief tank is greater than 0.25MPa or the liquid level of the pressure relief tank is greater than 1.75m, the indicator is met.

9. The precise automatic control method for air cavity replacement in a nuclear power plant pressurizer according to claim 1, characterized in that: In step S2-5: if the pressure of a circuit is greater than 1.9 MPa, the indicator is met.

10. The precise automatic control method for air cavity replacement in a nuclear power plant pressurizer according to claim 1, characterized in that: In the steps S2-2 to S2-6, if the pressure of a circuit is less than 1.7MPa or the pressure of the pressure relief tank is greater than 0.25MPa or the liquid level of the pressure relief tank is greater than 1.8m or the stabilizer exhaust electric valve fault alarm or the stabilizer nitrogen supply pipeline electric valve fault alarm is issued, it is automatically monitored and determined as an abnormal air cavity replacement, and the stabilizer exhaust electric valve is automatically closed.

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