Precise automatic control method for replacing air cavity in pressurizer of nuclear power plant

Abstract

The present application relates to the field of nuclear power plant operation and automatic control, and particularly relates to a precise automatic control method for replacing a gas cavity in a nuclear power plant stabilizer. The method comprises: during the start of a reactor device, executing an automatic control program to automatically replace a nitrogen cavity with a steam cavity in the stabilizer; and during the cooling of the reactor device, executing an automatic control program to automatically replace the steam cavity in the stabilizer with the nitrogen cavity. The present application realizes full automatic control for replacing the gas cavity in the stabilizer, avoids human errors, effectively controls risks, and improves the replacement efficiency.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of nuclear power plant operation and automatic control, and particularly relates to a precise automatic control method for replacing a gas cavity in a nuclear power plant stabilizer. BACKGROUND

[0002] During the shutdown of a pressurized water reactor nuclear power plant reactor device, when the primary coolant temperature drops to a certain level, the amount of steam generated in the stabilizer decreases, the buffering capacity of the stabilizer steam space to the pressure change of the primary loop decreases, the primary loop pressure fluctuation gradually increases, and then the primary loop coolant pump inlet pressure fluctuation is caused, which endangers its safe operation. In order to avoid the main pump removal, by providing non-condensable gas (nitrogen) into the stabilizer, the steam cavity is replaced by a nitrogen cavity, and the pressure of the stabilizer gas cavity space is ensured, so as to stabilize the primary loop pressure and the main pump inlet pressure.

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

[0004] The traditional stabilizer gas cavity replacement method is manual control, and the operator needs to closely monitor key parameters such as primary loop pressure and main coolant pump inlet pressure during replacement. The monitoring parameters are many and the task is heavy. Moreover, the manual control accuracy is not high, the primary loop pressure fluctuates greatly during replacement, a small amount of replacement is required, and the time is long. SUMMARY

[0005] The technical problem to be solved by the present application is to provide a precise automatic control method for replacing a gas cavity in a nuclear power plant stabilizer, to avoid human errors, effectively control risks, and improve replacement efficiency.

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

[0007] During the startup of a reactor device, the method specifically comprises the following steps:

[0008] Step S1-1: automatically monitoring the stabilizer liquid level and the primary loop main pipe temperature, if both meet the operation standard, an automatic operation signal is sent, and the next step is entered;

[0009] Step S1-2: determining whether the stabilizer can discharge nitrogen to the pressure relief tank, if the index is reached, the next step is entered;

[0010] Step S1-3: During the process of discharging nitrogen from the stabilizer to the pressure relief tank, the nitrogen cavity is automatically monitored and determined to be replaced by the steam cavity; if the index is reached, the next step is entered;

[0011] Step S1-4: The stabilizer exhaust electric valve is automatically closed, and the system returns to the initial state.

[0012] During the cooling of the reactor device, the following steps are specifically included:

[0013] Step S2-1: The unit is automatically monitored and determined to be in a shutdown condition, and the nitrogen supply pipeline is available.

[0014] Step S2-2: It is automatically monitored and determined whether the stabilizer can discharge steam to the pressure relief tank; if the index is reached, the next step is entered.

[0015] Step S2-3: The stabilizer discharges steam to the pressure relief tank, and it is automatically monitored and determined whether the discharge of steam is ended; if the index is reached, the next step is entered.

[0016] Step S2-4: An automatic command is issued to pulse open the stabilizer nitrogen supply pipeline electric valve.

[0017] Step S2-5: Nitrogen is supplied to the stabilizer, and it is automatically monitored and determined whether the first nitrogen supply is ended; if the index is reached, the next step is entered.

[0018] Step S2-6: It is automatically monitored and determined whether the steam cavity has been replaced by the nitrogen cavity; if the stabilizer exhaust electric valve is opened and the specified replacement time is reached, and the pressure relief tank pressure rises but the liquid level measured by the pressure relief tank liquid level meter does not change, the next step is entered; if the above conditions are not met, return to step S2-2.

[0019] Step S2-7: The stabilizer exhaust electric valve and the stabilizer gas supply are automatically closed, and the initial state is restored.

[0020] In a specific embodiment of the present application, in step S1-1, if the stabilizer liquid level is greater than 11.1 m and the primary circuit pipeline temperature is less than 150℃, the operation standard is met.

[0021] In a specific embodiment of the present application, in step S1-2, if the primary circuit pressure is greater than 1.9 MPa, and the pressure relief tank pressure is less than 0.02 MPa, and the liquid level of the pressure relief tank is less than 1.8 m, the stabilizer exhaust electric valve is automatically pulsed opened, and the next step is entered.

[0022] In a specific embodiment of the present application, in steps S1-2 and S1-3, if the loop pressure is less than 1.8M, or the pressure relief tank pressure is greater than 0.15M, or the pressure relief tank liquid level is greater than 2m, or the pressure stabilizer exhaust electric valve fails to alarm, it is automatically determined that the steam cavity replacement is abnormal, and the pressure stabilizer exhaust electric valve is automatically closed.

[0023] In a specific embodiment of the present application, in step S1-3, when the pressure stabilizer exhaust electric valve is opened and reaches the specified replacement time, and the liquid level of the pressure relief tank is raised but the pressure relief tank pressure is unchanged, the index is reached, and the next step is entered.

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

[0025] The pressure stabilizer liquid level is automatically monitored to be greater than 10.9m, and the loop main pipe temperature is greater than 140℃, and the pressure relief tank pressure is less than 0.02MPa, and the nitrogen supply pipeline pressure is greater than 1.9MPa, allowing the gas cavity to be replaced by steam with nitrogen, and entering the next step.

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

[0027] If the loop 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 index is reached.

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

[0029] If the loop 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 index is reached.

[0030] In a specific embodiment of the present application, in step S2-5, if the loop pressure is greater than 1.9MPa, the index is reached.

[0031] In steps S2-2 to S2-6 of a specific embodiment of the present application, if the loop pressure is less than 1.7MPa or the pressure relief tank pressure is greater than 0.25MPa or the pressure relief tank liquid level is greater than 1.8m or the pressure stabilizer exhaust electric valve fails to alarm, or the pressure stabilizer nitrogen supply pipeline electric valve fails to alarm, it is automatically monitored and determined that the gas cavity replacement is abnormal, and the pressure stabilizer exhaust electric valve is automatically closed.

[0032] Compared with the prior art, the precise automatic control method for replacing the gas cavity in the pressure stabilizer of the nuclear power plant has the following beneficial effects:

[0033] (1) Automatic detection of the primary loop temperature, the stabilizer liquid level, the relief tank liquid level and pressure, the main pump running state and the nitrogen pressure, etc. parameters to automatically determine whether the unit is in a running state that can be replaced by the gas cavity to avoid the unit entering the transient state caused by the non-expected input of the program;

[0034] (2) Automatic monitoring of the primary loop pressure, the relief tank pressure and liquid level, and then automatically pulsing the opening or closing of the stabilizer to the relief tank exhaust electric valve, while automatically monitoring the primary loop pressure, the nitrogen supply pipeline pressure, and then automatically pulsing the opening or closing of the nitrogen supply electric valve to the stabilizer, to realize accurate control of the replacement gas flow, effectively reduce the primary loop pressure fluctuation during replacement, shorten the replacement time, improve the replacement efficiency, and ensure the safe operation of the main pump;

[0035] (3) Automatic determination of the completion of the replacement of the gas cavity, and automatic closing of the related valves to restore the system to the initial state, reducing the time-consuming of manual determination and operation;

[0036] (4) Automatic monitoring of the primary loop pressure, the relief tank pressure and liquid level, and the electric valve state, when the parameters are out of limits or the valve is abnormal, the system is automatically placed in a safe state

[0037] (5) Automatic monitoring of the related parameters, partially reducing the monitoring task of the operator during the start and stop of the unit, and reducing the risk of human error. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 The device structure schematic diagram involved in the replacement of the gas cavity in the stabilizer of a nuclear power plant is shown.

[0039] In the figure, 1 is a stabilizer; 2 is a primary loop main pipeline; 3 is a reactor; 4 is a primary loop pressure gauge; 5 is a relief tank; 6 is a relief tank liquid level meter; 7 is a relief tank pressure gauge; 8 is a stabilizer exhaust pipeline; 9 is a stabilizer exhaust electric valve; 10 is a stabilizer nitrogen supply pipeline; 11 is a stabilizer nitrogen supply pipeline electric valve; 12 is a nitrogen supply pipeline pressure gauge; 13 is a stabilizer liquid level meter; and 14 is a primary loop main pipeline thermometer. DETAILED DESCRIPTION

[0040] In order to further understand the present application, the embodiments of the present application are described below in conjunction with the examples, but it should be understood that these descriptions are only for further illustrating the features and advantages of the present application, but not limiting the present application.

[0041] The precise automatic control method for the replacement of the gas cavity in the stabilizer of a nuclear power plant in the present application is based on Figure 1 The device shown in the figure is realized.

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

[0043] During the start-up of the reactor device, the method specifically comprises the following steps:

[0044] Step S1-1: The stabilizer liquid level and the primary loop main pipeline temperature are automatically monitored, if the stabilizer liquid level is greater than 11.1 m and the primary loop main pipeline temperature is less than 150 DEG C, the operation standard is met, an operation permission signal is automatically sent out, and the next step is entered.

[0045] Step S1-2: It is determined whether the stabilizer can discharge nitrogen to the pressure relief tank, if the primary loop pressure is greater than 1.9 MPa, the pressure relief tank pressure is less than 0.02 MPa, and the pressure relief tank liquid level is less than 1.8 m, the stabilizer exhaust electric valve is automatically opened by pulse, and the next step is entered.

[0046] Step S1-3: During the process that the stabilizer discharges nitrogen to the pressure relief tank, the nitrogen cavity is automatically monitored and determined to be replaced by the steam cavity; when the stabilizer exhaust electric valve is opened and reaches the specified replacement time, and the pressure relief tank liquid level rises but the pressure relief tank pressure remains unchanged, the index is reached, and the next step is entered.

[0047] In the step S1-2 and the step S1-3, if the primary loop pressure is less than 1.8 M, or the pressure relief tank pressure is greater than 0.15 M, or the pressure relief tank liquid level is greater than 2 m, or the stabilizer exhaust electric valve fails to alarm, the steam cavity replacement is automatically determined to be abnormal, and the stabilizer exhaust electric valve is automatically closed.

[0048] Step S1-4: The stabilizer exhaust electric valve is automatically closed, and the system returns to the initial state.

[0049] During the cooling of the reactor device, the method specifically comprises the following steps:

[0050] Step S2-1: The unit is automatically monitored and determined to be in the shutdown condition, and the nitrogen supply pipeline is available.

[0051] Specifically, the method comprises the following steps:

[0052] The stabilizer liquid level is automatically monitored to be greater than 10.9 m, the primary loop main pipeline temperature is greater than 140 DEG C, the pressure relief tank pressure is less than 0.02 MPa, and the nitrogen supply pipeline pressure is greater than 1.9 MPa, the gas cavity is allowed to be replaced from steam to nitrogen, and the next step is entered.

[0053] Step S2-2: automatically monitor and determine whether the pressurizer can discharge steam to the relief tank, if the primary loop pressure is greater than 1.9 MPa and the pressure of the relief tank is less than 0.02 MPa and the liquid level of the relief tank is less than 1.7 m, the index is reached, and the next step is entered;

[0054] Step S2-3: the pressurizer discharges steam to the relief tank, automatically monitors and determines whether the discharge of steam is completed, if the primary loop pressure is less than 1.8 MPa or the pressure of the relief tank is greater than 0.25 MPa or the liquid level of the relief tank is greater than 1.75 m, the index is reached, and the next step is entered;

[0055] Step S2-4: automatically command, pulse open the electric valve of the pressurizer nitrogen supply pipeline;

[0056] Step S2-5: supply nitrogen to the pressurizer, automatically monitor and determine whether the first nitrogen supply is completed, if the primary loop pressure is greater than 1.9 MPa, the index is reached, and the next step is entered;

[0057] Step S2-6: automatically monitor and determine whether the steam cavity has been replaced by a nitrogen cavity, if the pressurizer exhaust electric valve is opened and the specified replacement time is reached and the pressure of the relief tank rises but the liquid level measured by the relief tank liquid level meter does not change, the next step is entered, and if the above conditions are not met, the step S2-2 is returned;

[0058] Step S2-7: automatically close the pressurizer exhaust electric valve and the pressurizer gas supply, and restore the initial state.

[0059] In the steps S2-2 to S2-6, if the primary loop pressure is less than 1.7 MPa or the pressure of the relief tank is greater than 0.25 MPa or the liquid level of the relief tank is greater than 1.8 m or the pressurizer exhaust electric valve fails to alarm or the pressurizer nitrogen supply pipeline electric valve fails to alarm, the gas cavity replacement is abnormally determined, and the pressurizer exhaust electric valve is automatically closed.

[0060] In summary, the application designs and uses a gas cavity replacement automatic control program, automatically determines whether the unit state allows the gas cavity replacement operation to be performed, and has inherent safety;

[0061] On the basis of not changing the original design and layout of the system, parameters are collected in real time and the gas cavity replacement in the pressurizer is automatically and accurately performed;

[0062] According to the real-time collected parameters, it is automatically determined that the gas cavity replacement is completed, and the system is automatically placed to the initial state;

[0063] According to the real-time collected parameters and the state of the electric valve, it is automatically determined that the parameters are out of limit or the valve is abnormal, and the system is automatically placed to the safe state;

[0064] According to the secondary combination of limits and conditions of a large number of primary circuit key parameters required by each step, the pre-replacement, replacement, completion and abnormal replacement of the air cavity are accurately determined.

[0065] Through the technical scheme of the present application, the following technical effects are achieved:

[0066] The replacement operation is automatically performed, the operator does not need to closely monitor the primary circuit pressure and other parameters during the replacement, the monitoring pressure is reduced, and human error is avoided;

[0067] The primary circuit pressure is accurately controlled during the air cavity replacement, the primary circuit pressure fluctuation is reduced, and the replacement efficiency is improved;

[0068] If the key parameters deviate, the replacement operation is immediately automatically stopped and placed in a safe state.

[0069] The above description of the embodiments is only used to help understand the method of the present application and its core idea. It should be pointed out that for ordinary skilled persons in the art, some improvements and modifications can be made to the present application without departing from the principles of the present application, and these improvements and modifications also fall within the protection scope of the claims of the present application.

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

Claims

1. A precise automatic control method for gas cavity replacement in a nuclear power plant pressurizer, characterized in that: The method includes executing an automatic control program during the startup of the reactor device to automatically replace the nitrogen cavity with a steam cavity in the pressurizer; and executing an automatic control program during the cooling period of the reactor device to automatically replace the steam cavity in the pressurizer with a nitrogen cavity; The reactor startup process includes the following steps: Step S1-1: Automatically monitor the pressurizer liquid level and the primary circuit main pipe temperature. If both meet the commissioning standards, automatically issue 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 into the pressure relief box, the pressurizer automatically monitors and determines whether the nitrogen chamber has been replaced by the steam chamber; if the indicator is met, the pressurizer proceeds to the next step; Step S1-4: Automatically close the regulator exhaust electric valve and restore the system to its initial state; The cooling period of the reactor unit specifically 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 met, the process proceeds to the next step. Step S2-4: issuing an automatic command to pulse open the electric valve of the nitrogen supply pipeline of the regulator; Step S2-5: supplying nitrogen to the regulator, automatically monitoring and determining whether the first nitrogen supply is completed. If the indicator is met, 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 pressurizer 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 pressurizer liquid level is greater than 11.1 m and the primary circuit main pipeline temperature is less than 150°C, the operation standard is met.

3. The precise automatic control method for gas cavity replacement in a nuclear power plant pressurizer according to claim 1, characterized in that: In step S1-2, if the primary circuit pressure is greater than 1.9 MPa, the pressure of the pressure relief tank is less than 0.02 MPa, and the liquid level of the pressure relief tank is less than 1.8 m, 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 one 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 pressure regulator exhaust electric valve fault alarm is issued, it is automatically determined that the steam chamber replacement is abnormal, and the pressure regulator 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 met 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: Automatically monitor the pressurizer liquid level to be greater than 10.9m, the primary circuit main pipeline temperature to be greater than 140°C, the pressure in the pressure relief tank to be less than 0.02MPa, and the nitrogen supply pipeline pressure to be greater than 1.9MPa, allowing the air cavity to be replaced by steam with nitrogen and proceed to 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 the first 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 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 that the air cavity replacement is abnormal, and the stabilizer exhaust electric valve is automatically closed.

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