Method for verifying cooling performance of passive residual heat removal system

Abstract

The invention relates to a method for verifying the cooling performance of a passive residual heat removal system, which comprises the following steps: a preparation step: controlling an HPR1000 unit, and keeping the average temperature of a primary loop, the pressure of the primary loop, the liquid level of a pressure stabilizer, the pressure of three steam generators and the liquid levels of the three steam generators in corresponding set ranges, the heat of the primary loop can only be led out through the passive residual heat removal system; a test step: triggering a protection function of the passive residual heat removal system, and leading out heat of a loop through a tested column condenser in the passive residual heat removal system; recording the duration of waste heat exporting of the condenser, and continuously monitoring the average temperature of the first loop, the pressure of the first loop, the liquid level of the pressure stabilizer, the pressure of the three steam generators and the liquid levels of the three steam generators so as to obtain test data; and determining whether the cooling performance of the tested train meets a set requirement or not according to the test data. According to the invention, whether the cooling performance of the passive residual heat removal system meets the set requirements can be verified.

Description

Technical Field

[0001] The present invention relates to the technical field of passive residual heat removal systems, and particularly to a method for verifying the cooling performance of a passive residual heat removal system. Background Art

[0002] In a nuclear power plant, the passive residual heat removal system is mainly used to conduct heat from the reactor core under severe accident conditions of DEC (DEC-A: Design Extension Condition without significant damage to the reactor core). The working condition it responds to is when the emergency feedwater system needs to be put into operation to remove the heat of the primary loop, but due to a failure, the emergency feedwater system fails. In this accident condition, the passive residual heat removal system shoulders the heavy responsibility of removing the heat of the primary loop. Therefore, the cooling performance of the passive residual heat removal system is particularly important. However, at present, there is a lack of a solution in the industry that can accurately evaluate the cooling performance of the passive residual heat removal system, making it difficult to ensure the rationality of the design of the passive residual heat removal system. Overprotection can ensure that the performance meets the requirements, but it has the defect of high cost, while insufficient protection poses a safety risk. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a method for verifying the cooling performance of a passive residual heat removal system.

[0004] The technical solution adopted by the present invention to solve its technical problem is to construct a method for verifying the cooling performance of a passive residual heat removal system for an HPR1000 unit. The HPR1000 unit includes a passive residual heat removal system, a primary loop, a pressurizer, and three steam generators. The method includes:

[0005] Preparation step: Control the HPR1000 unit to keep the average temperature of the primary loop within a first set temperature range, the pressure of the primary loop within a first set pressure range, the liquid level of the pressurizer within a first set liquid level range, the pressure of the three steam generators within a second set pressure range, and the liquid level of the three steam generators within a second set liquid level range, and make the heat of the primary loop can only be exported through the passive residual heat removal system;

[0006] Test procedure: Trigger the protection function of the passive residual heat removal system, and export the heat of the primary loop through the condenser of the tested train in the passive residual heat removal system; record the duration of the residual heat exported by the condenser of the tested train, and simultaneously continuously monitor the average temperature of the primary loop, the pressure of the primary loop, the level of the pressurizer, the pressures of the three steam generators, and the levels of the three steam generators until the duration reaches the first set time or the average temperature of the primary loop drops to the set temperature value, so as to obtain test data; determine whether the cooling performance of the tested train meets the set requirements according to the test data.

[0007] Preferably, in the preparation step, the control of the HPR1000 unit includes:

[0008] Control the HPR1000 unit to be in the hot shutdown condition, control the proportional heaters in the HPR1000 unit and the operator assistance functions related to the primary loop pressure control to be put into operation, and set the average temperature of the primary loop to the set temperature value and the pressure of the primary loop to the first set pressure value, so that the average temperature of the primary loop is maintained within the first set temperature range and the pressure of the primary loop is maintained within the first set pressure range;

[0009] Control the pressurizer to be in the automatic control mode, put the operator assistance protection function related to the pressurizer level control into operation, and set the level of the pressurizer to the first set level value, so that the level of the pressurizer is maintained within the first set level range;

[0010] Control the charging pumps and the three main pumps in the HPR1000 unit to run, set the three steam generators to the automatic control mode and put the blowdown function of the three steam generators into operation, and set the levels of the three steam generators to the second set level value, so that the levels of the three steam generators are maintained within the second set level range;

[0011] Control the main steam line isolation valve in the HPR1000 unit to open, set the turbine bypass system in the HPR1000 unit to the pressure control mode, and set the pressures of the three steam generators to the second set pressure value, so that the pressures of the three steam generators are maintained within the second set pressure range;

[0012] Control the main steam release isolation valve of the steam atmosphere discharge system in the HPR1000 unit to be closed, control the opening of the main steam release control valve of the steam atmosphere discharge system to be set to a first set opening, control the emergency water supply system in the HPR1000 unit to be shut down, control the isolation of the primary and secondary loop sampling pipelines in the HPR1000 unit, isolate the coolant storage tank downflow pipeline between the volume control system and the reactor coolant treatment system in the HPR1000 unit, control the inlet steam isolation valve, inlet steam regulating valve and reflux isolation valve of the tested column to be in the working position, control the inlet steam isolation valve, inlet steam regulating valve and reflux isolation valve of all other columns in the HPR1000 unit except the tested column to be in the isolation position, so that the condenser of the tested column in the passive residual heat removal system can only export residual heat through the preset tested column.

[0013] Preferably, the controlling the HPR1000 unit further comprises:

[0014] The liquid level of the water collecting tank in the passive waste heat removal system is controlled to be maintained within the third set liquid level range, the liquid temperature of the water collecting tank is controlled to be maintained within the second set temperature range, and the liquid level of the condenser of the tested column is controlled to be maintained within the fourth set liquid level range.

[0015] Preferably, the first set temperature range is 293°C to 297°C, the first set pressure range is 15.3MPa.g to 15.5MPa, the first set liquid level range is 34% to 38%, the second set pressure range is 7.8MPa.g to 8.0MPa.g, the second set liquid level range is 48% to 52%, the third set liquid level range is 6.3m to 6.6m, the second set temperature range is 5°C to 50°C, and the fourth set liquid level range is 3.7m to 4.0m.

[0016] Preferably, the controlling the HPR1000 unit further comprises:

[0017] The HPR1000 unit is placed in a temporary control change condition so that the protection functions of the HPR1000 unit except the protection function of the passive residual heat removal system are locked, and the diesel engine start signal in the plant power failure condition is not triggered.

[0018] Preferably, the first set time is 30 minutes; and / or the set temperature value is 285°C.

[0019] Preferably, in the test step, triggering the protection function of the passive residual heat removal system so that the heat of the primary circuit is discharged through the condenser of the tested column in the passive residual heat removal system comprises:

[0020] Set the pressure controller of the pressure stabilizer to manual mode, set the on-off heater in the HPR1000 unit to automatic control mode, control the closing of the isolation valves of the feed water pipelines of the three steam generators, and then trigger the protection function of the passive residual heat removal system;

[0021] After the protection function of the passive residual heat removal system is triggered for a second set time, determine whether the reactor protection signal of the passive residual heat removal system is triggered. If so, control the opening of the inlet steam isolation valve and the inlet steam regulating valve of the test train, close the main valves of the three main steam discharge systems in the HPR1000 unit, and close the blowdown isolation valve of the steam generator blowdown system in the HPR1000 unit;

[0022] After the protection function of the passive residual heat removal system is triggered for a third set time, control the opening of the reflux isolation valve of the test train and control the locking of the turbine bypass system in the HPR1000 unit.

[0023] Preferably, after the test step, it further includes:

[0024] Unit recovery step:

[0025] Control the opening of the blowdown isolation valve of the steam generator blowdown system;

[0026] Set the pressure controller to automatic control mode, and set the proportional heater and the on-off heater in the HPR1000 unit to automatic control mode;

[0027] Control the opening of the isolation valves of the feed water pipelines of the three steam generators;

[0028] Control the unlocking of the turbine bypass system;

[0029] Control the opening of the inlet steam regulating valve and the steam inlet pipeline drain valve of the test train;

[0030] Monitor the steam pipeline pressure of the passive residual heat removal system, and when the steam pipeline pressure is less than the third set pressure value, control the sequential closing of the inlet steam regulating valve of the test train and the drain valve of the passive residual heat removal system;

[0031] Control the condenser of the test train to be filled with water so that the liquid level of the condenser of the test train is maintained within the fifth set liquid level range, and then control the sequential closing of the water filling isolation valve of the reflux pipeline, the demineralized water filling isolation valve of the ASP system water tank, and the condenser drain isolation valve in the passive residual heat removal system;

[0032] Open the nitrogen charging isolation valve for the test column to be controlled, and close the nitrogen charging isolation valve after a fourth set time.

[0033] When the steam pipeline pressure enters the third set pressure range, close the system pipeline nitrogen charging isolation valve in the passive residual heat removal system and let it stand for a fifth set time.

[0034] Preferably, in the test step, it further includes:

[0035] Determine whether the HPR1000 unit has an abnormality.

[0036] When the HPR1000 unit has an abnormality, reset the start signal of the passive residual heat removal system through the manual reset control in the passive residual heat removal system, and sequentially close the reflux isolation valve, the inlet steam isolation valve, and the inlet steam regulating valve of the test column to be controlled; control the opening of the feed water isolation valve in the three steam generators, and control the opening of the feed water isolation valve in the three steam generators; control the blowdown of the three steam generators; and adjust the letdown pressure of the volume control system in the HPR1000 unit according to the operation.

[0037] Preferably, between the preparation step and the test step, it further includes:

[0038] Warm-up step: Control the opening of the main steam pipeline drain valve in the HPR1000 unit, and put into operation the drain pipeline of the main steam discharge system in the HPR1000 unit; control the opening of the inlet steam isolation valve of the test column to be controlled, and control the opening of the inlet steam regulating valve of the test column to be controlled to a second set opening, continuously obtain the steam inlet pipeline pressure and the main pipe pressure of the main steam discharge system, when the steam inlet pipeline pressure rises to be close to or equal to the main pipe pressure, control the inlet steam regulating valve of the test column to be controlled to be fully open, and close the inlet steam isolation valve and the inlet steam regulating valve of the test column to be controlled after a sixth set time; determine whether the main steam discharge system triggers a main valve condensation risk alarm, if not, control the closing of the main steam pipeline drain valve and isolate the drain pipeline of the main steam discharge system; determine whether the liquid level of the condenser of the test column to be controlled is not within the seventh set liquid level range, if so, control the liquid level of the condenser of the test column to be controlled to be kept within the seventh set liquid level range.

[0039] Implementing the present invention has the following beneficial effects: providing a method for verifying the cooling performance of a passive residual heat removal system, which can verify whether the cooling performance of the passive residual heat removal system meets the set requirements, so as to guide the subsequent accurate and efficient heat conduction of the reactor core in the HPR1000 unit in the event of a severe DEC accident, helping to accelerate the maintenance progress of the passive residual heat removal system during the major overhaul and improving the economic benefits of the unit. Brief Description of the Drawings

[0040] The present invention will be further described below in conjunction with the drawings and embodiments. In the drawings:

[0041] Figure 1 is a program flowchart of a method for verifying the cooling performance of a passive residual heat removal system in an embodiment of the present invention. Detailed Embodiments

[0042] For a clearer understanding of the technical features, objectives, and effects of the present invention, the detailed embodiments of the present invention will now be described with reference to the drawings.

[0043] It should be noted that the flowchart shown in the drawings is only an exemplary illustration, and does not necessarily include all the contents and operations / steps, nor does it necessarily need to be executed in the described order. For example, some operations / steps can be decomposed, while some operations / steps can be combined or partially combined. Therefore, the actual execution order may change according to the actual situation.

[0044] The block diagrams shown in the drawings are only functional entities, and do not necessarily correspond to physically independent entities. That is, these functional entities can be implemented in software form, or implemented in one or more hardware modules or integrated circuits, or implemented in different networks and / or processor devices and / or microcontroller devices.

[0045] Figure 1 is a program flowchart of a method for verifying the cooling performance of a passive residual heat removal system in an embodiment of the present invention. This method for verifying the cooling performance of the passive residual heat removal system is used for the HPR1000 unit. The HPR1000 unit includes a passive residual heat removal system (referred to as the ASP system for short), a primary circuit, a pressurizer, and three steam generators, on-off heaters, proportional heaters, charging pumps, three main pumps (i.e., reactor coolant pumps), main steam line isolation valves, a turbine bypass system, a steam atmospheric discharge system, primary and secondary circuit sampling pipelines, a volume control system, a reactor coolant treatment system, three main steam discharge systems, a steam generator blowdown system, a turbine bypass system, main steam line drain valves, and a main steam discharge system, etc. Among them, the passive residual heat removal system includes three rows of heat removal components A, B, and C (referred to as row A, row B, and row C for short). It should be noted that the HPR1000 unit is a nuclear power unit with mature technology. For the functions, circuits, and mechanical structures of each device included in the HPR1000 unit, please refer to the prior art. Further, for the specific methods of controlling the HPR1000 unit, reference can also be made to the prior art, which will not be elaborated here.

[0046] As Figure 1 shown, this method for verifying the cooling performance of the passive residual heat removal system may include a preparation step and a test step.

[0047] Among them, the preparation step may include: controlling the HPR1000 unit to keep the average temperature of the primary loop within a first set temperature range, the pressure of the primary loop within a first set pressure range, the liquid level of the pressurizer within a first set liquid level range, the pressures of the three steam generators within a second set pressure range, and the liquid levels of the three steam generators within a second set liquid level range, and enabling the heat of the primary loop to be discharged only through the passive residual heat removal system.

[0048] In one embodiment, the specific process of controlling the HPR1000 unit may include steps S11 to S15.

[0049] Step S11 includes: controlling the HPR1000 unit to be in a hot shutdown condition, controlling the proportional heaters in the HPR1000 unit and the operator assistance functions related to the primary loop pressure control to be put into operation, and setting the average temperature of the primary loop to a set temperature value and the pressure of the primary loop to a first set pressure value, so as to keep the average temperature of the primary loop within the first set temperature range and the pressure of the primary loop within the first set pressure range.

[0050] In this step, controlling the HPR1000 unit to operate in the hot shutdown condition is to avoid the mechanical work of the reactor core and stop generating heat, providing a basic regulation for stabilizing the temperature and pressure of the primary loop. The proportional heaters can control the average temperature of the primary loop to be close to the set temperature value to achieve "the average temperature of the primary loop is kept within the first set temperature range". In addition, in order to avoid the influence of other equipment on the temperature of the primary loop, the on-off heaters can be controlled to be out of service while the proportional heaters are put into operation. And the operation of the operator assistance functions related to the primary loop pressure control can automatically make the pressure of the primary loop as close as possible to the first set pressure value to achieve "the pressure of the primary loop is kept within the first set pressure range". It can be understood that this step can construct a stable test environment for the temperature and pressure of the primary loop.

[0051] Optionally, the set temperature value may be 295 °C, the first set temperature range may be 293 °C to 297 °C. Correspondingly, generally, setting the input power of the proportional heaters to 46.3% can meet the requirement of keeping the average temperature of the primary loop within the first set temperature range. The first set pressure value may be 15.4 MPa.g, and the first set pressure range may be 15.3 MPa.g to 15.5 MPa.

[0052] It should be noted that after the operation of the operator assistance functions related to the primary loop pressure control, it can automatically control the pressure of the primary loop not to deviate too much from the pressure set value of the primary loop.

[0053] Step S12 includes: controlling the pressurizer to be in the automatic control mode, putting into operation the operator-aided protection functions related to the pressurizer liquid level control, and setting the liquid level of the pressurizer to the first set liquid level value so that the liquid level of the pressurizer is maintained within the first set liquid level range. After the operator-aided protection functions related to the pressurizer liquid level control are put into operation, an alarm can be given when the liquid level of the pressurizer exceeds the protection threshold to prompt the staff that the unit has an abnormality. In addition, when the pressurizer is in the automatic control mode, the liquid level of the pressurizer can be made as close as possible to the first set liquid level value to achieve "the liquid level of the pressurizer is maintained within the first set liquid level range".

[0054] Optionally, the first set liquid level value can be 36%, and correspondingly, the first set liquid level range can be from 34% to 38%.

[0055] It can be understood that this step can keep the liquid level of the pressurizer at a relatively low water level, ensuring that the pressurizer has a certain liquid level margin to achieve the voltage stabilizing function and guaranteeing the safety of the test process.

[0056] Step S13 includes: controlling the charging pump and three main pumps in the HPR1000 unit to run, setting the three steam generators to the automatic control mode and putting into operation the blowdown functions of the three steam generators, and setting the liquid levels of the three steam generators to the second set liquid level value so that the liquid levels of the three steam generators are maintained within the second set liquid level range.

[0057] In this step, controlling the charging pump and three main pumps to run provides the driving force for controlling the liquid levels of the three steam generators; when the three steam generators are in the automatic control mode, they can automatically make their liquid levels as close as possible to the second set liquid level value to achieve "the liquid levels of the three steam generators are maintained within the second set liquid level range".

[0058] Optionally, the second set liquid level value can be 36%, and correspondingly, the second set pressure range can be from 7.8 MPa.g to 8.0 MPa.g.

[0059] Furthermore, in order to improve the liquid level control accuracy of the steam generators, the opening degree of the minimum load control valve of the main feed water pipeline in each steam generator can also be controlled to make the liquid level of the steam generator as close as possible to the second set liquid level value.

[0060] Step S14 includes: controlling the opening of the main steam pipeline isolation valve in the HPR1000 unit, setting the steam turbine bypass system in the HPR1000 unit to the pressure control mode, and setting the pressures of the three steam generators to the second set pressure value so that the pressures of the three steam generators are maintained within the second set pressure range.

[0061] In this step, in the pressure control mode, the steam turbine bypass system can control the pressures of the three steam generators to automatically maintain at the second set pressure value, so as to achieve "the pressures of the three steam generators are maintained within the second set pressure range".

[0062] Optionally, the second set pressure value can be 7.9 MPa.g. Correspondingly, the second set liquid level range can be 48% to 52%.

[0063] Step S15 includes: controlling the main steam release isolation valve of the steam atmosphere discharge system in the HPR1000 unit to close, setting the opening degree of the main steam release control valve of the steam atmosphere discharge system to the first set opening degree, controlling the emergency feed water system in the HPR1000 unit to stop operating, controlling the sampling pipelines of the primary circuit and the secondary circuit in the HPR1000 unit to be isolated, isolating the coolant storage tank drain pipeline between the volume control system and the reactor coolant treatment system in the HPR1000 unit, controlling the inlet steam isolation valve, the inlet steam regulating valve and the reflux isolation valve of the test train to be in the working position, and controlling the inlet steam isolation valves, the inlet steam regulating valves and the reflux isolation valves of all other trains except the test train in the HPR1000 unit to be in the isolated position, so that the condenser of the test train in the passive residual heat removal system can only export the residual heat through the preset test train. Among them, the first set opening degree can be 40%.

[0064] In this step, by closing the main steam release isolation valve, setting the opening degree of the main steam release control valve to the first set opening degree, stopping the operation of the emergency feed water system, isolating the sampling pipelines of the primary circuit and the secondary circuit, isolating the coolant storage tank drain pipeline between the volume control system and the reactor coolant treatment system, making the inlet steam isolation valve, the inlet steam regulating valve and the reflux isolation valve of the test train all in the working position, and making the inlet steam isolation valves, the inlet steam regulating valves and the reflux isolation valves of all other trains (i.e., the other two trains) except the test train in the isolated position, it is to isolate the residual heat export path except the passive residual heat removal system and prepare for exporting the residual heat only through the condenser of the test train in the passive residual heat removal system. It should be noted that the inlet steam isolation valve, the inlet steam regulating valve and the reflux isolation valve being in the working position means that the opening degrees of the inlet steam isolation valve, the inlet steam regulating valve and the reflux isolation valve can all be controlled by the unit. For example, the staff can control the opening degrees of these valves in the main control room. On the contrary, if the inlet steam isolation valve, the inlet steam regulating valve and the reflux isolation valve are in the isolated position, these valves will be de-energized and cannot be controlled, thus ensuring that the valves will not malfunction.

[0065] In order to be able to construct a more stable test condition, which helps to improve the safety and reliability of the test, in one embodiment, the specific process of controlling the HPR1000 unit can include step S16.

[0066] Step S16 includes: controlling the liquid level of the water collecting tank in the passive residual heat removal system to be maintained within the third set liquid level range, the liquid temperature of the water collecting tank to be maintained within the second set temperature range, and controlling the liquid level of the condenser of the tested column to be maintained within the fourth set liquid level range. The third set liquid level range may be 6.3m to 6.6m, the second set temperature range may be 5°C to 50°C, and the fourth set liquid level range may be 3.7m to 4.0m.

[0067] In order to avoid that the protection functions of the unit other than the protection function of the passive residual heat removal system are triggered to affect the test results, and to avoid malfunction of the diesel generator used for emergency power supply, in one embodiment, the specific process of controlling the HPR1000 unit may include step S17.

[0068] Step S17 includes: placing the HPR1000 unit in a temporary control change condition so that the protection functions of the HPR1000 unit except the protection function of the passive residual heat removal system are locked, and the diesel engine start signal in the plant power failure condition is not triggered.

[0069] The test steps may include: triggering the protection function of the passive waste heat removal system to allow the heat of a circuit to be discharged through the condenser of the tested column in the passive waste heat removal system; recording the duration of the condenser of the tested column to discharge the waste heat, and simultaneously continuously monitoring the average temperature of the circuit, the pressure of the circuit, the liquid level of the regulator, the pressure of the three steam generators, and the liquid level of the three steam generators until the duration reaches a first set time or the average temperature of the circuit drops to a set temperature value to obtain test data; determining whether the cooling performance of the tested column meets the set requirements based on the test data.

[0070] In the test procedure, after the protection function of the passive residual heat removal system is triggered, since other residual heat removal paths except the tested column have been isolated after the preparation step is completed, the residual heat can only be discharged through the condenser of the tested column, thereby constructing an environment for testing the cooling performance of the condenser of the tested column.

[0071] It should be noted that the monitoring deadline of the test data of "duration reaches the first set time" and "the average temperature of a circuit drops to the set temperature value" is used as the criterion for judgment based on whichever is reached first. That is, during the test, if the average temperature of a circuit has dropped to the set temperature value before the protection function triggering duration of the passive residual heat removal system reaches the first set time, the monitoring of the average temperature of a circuit, the pressure of a circuit, the liquid level of the pressurizer, the pressures of the three steam generators and the liquid level of the three steam generators will be stopped immediately; if the protection function triggering duration reaches the first set time, the monitoring work will be stopped even if the average temperature of a circuit has not dropped to the set temperature value.

[0072] In one embodiment, the protection function of the passive residual heat removal system can be triggered by performing steps S21 to S23, so that the heat of the primary loop is exported through the condenser of the tested train in the passive residual heat removal system.

[0073] Step S21 includes: setting the pressure controller of the pressurizer to the manual mode, setting the on-off heater in the HPR1000 unit to the automatic control mode, controlling the isolation valves of the feed water pipelines of the three steam generators to close, and then triggering the protection function of the passive residual heat removal system.

[0074] In this step, after the pressure controller is set to the manual mode, the on-off heater is set to the automatic control mode, and the isolation valves of the feed water pipelines of the three steam generators are closed, the staff can manually operate the HPR1000 unit to generate a temporary trigger signal to trigger the protection function of the passive residual heat removal system.

[0075] Step S22 includes: after the protection function of the passive residual heat removal system is triggered for a second set time, judging whether the reactor protection signal of the passive residual heat removal system is triggered. If so, controlling the inlet steam isolation valve and the inlet steam regulating valve of the tested train to open, closing the main valves of the three main steam discharge systems in the HPR1000 unit, and closing the blowdown isolation valve of the steam generator blowdown system in the HPR1000 unit. Among them, the second set time can be 60 s (seconds).

[0076] In this step, since this test is carried out on a real unit, in order to ensure the safety of the whole test process, it is necessary to determine that the reactor protection signal is triggered after the start of the test steps, so as to ensure that the relevant measures for protecting the reactor have been implemented. And controlling the inlet steam isolation valve and the inlet steam regulating valve of the tested train to open, closing the main valves of the three main steam discharge systems in the HPR1000 unit, so that in the passive residual heat removal system, the heat can only be exported through the condenser of the tested train to achieve the purpose of cooling through the tested train.

[0077] Step S23 includes: after the protection function of the passive residual heat removal system is triggered for a third set time, controlling the reflux isolation valve of the tested train to open and controlling the turbine bypass system in the HPR1000 unit to be blocked. Among them, the third set time is greater than the second set time and can be 93 s.

[0078] In this step, when the reflux isolation valve of the tested train is opened, it means that the tested train is put into operation, and the heat of the primary loop will be exported from the condenser of the tested train. In addition, since the triggering of the protection function of the passive residual heat removal system involves the switching of a large number of related devices and requires a certain time to implement, the reflux isolation valve of the tested train is controlled to open only after the protection function of the passive residual heat removal system is triggered for the third set time.

[0079] Optionally, the first set time can be 30 min (minutes). The set temperature value can be 285 °C.

[0080] In a specific embodiment, the temperature of the primary circuit drops from 295.4 °C to 284.4 °C at the lowest, the temperature gradient gradually increases to -26 °C / h and tends to be stable, the pressure of the primary circuit drops from 15.43 MPa.g to 15.11 MPa.g at the lowest, the water level of the primary circuit drops from 36.7% to 32% at the lowest, and the pressures of the three steam generators gradually decrease. Among them, the pressure of the steam generator in the tested train drops from 7.86 MPa.g to 6.6 MPa.g at the lowest, and the liquid levels of the three steam generators rise slightly. Among them, the liquid level of the steam generator in the tested train rises from 14 m to 14.16 m at the highest, proving the feasibility of this test method.

[0081] In one embodiment, as Figure 1 shown, after the test steps, a unit restoration step may further be included.

[0082] The unit restoration step includes steps S31 to S39. It should be noted that steps S31 to S39 are executed in sequence.

[0083] Step S31 includes: controlling the opening of the drain isolation valve of the steam generator blowdown system. The purpose of this step is to restore the heat conduction function of the primary circuit and enable the heat to be exported through the primary circuit as soon as possible. Further, when the pressure of the steam generator in the tested train is lower than that of the normal trains, after the steam generator blowdown system is put into operation, water may flow from the other two steam generators into the tested train, which may trigger the high water level alarm of the steam generator. Moreover, the test steps also cause the demineralized water in the nuclear island of the condensate return pipeline to enter the steam generator, which may cause the pH value and dissolved oxygen to exceed the limit values for a short time. Therefore, it is necessary to blow down the steam generator as soon as possible. Specifically, it may include: first putting into operation the steam generator blowdown of the two trains except the tested train, and then closing the drain valve of the steam generator in the tested train completely to slow down the rise of the steam generator liquid level. After the pressure of the steam generator in the tested train is the same as that of the other two steam generators, then put into operation the steam generator blowdown of the tested train.

[0084] Step S32 includes: setting the pressure controller to the automatic control mode, and setting the proportional heater and on-off heater in the HPR1000 unit to the automatic control mode. The purpose of this step is to restore the pressure controller, proportional heater and on-off heater to the automatic control mode and restore the pressure and temperature of the primary circuit to the conventional control mode.

[0085] Step S33 includes: controlling the opening of the feed water pipeline isolation valves of the three steam generators. The purpose of this step is to restore the water supply function of the three steam generators.

[0086] Step S34 includes: controlling the unlocking of the steam turbine bypass system. The purpose of this step is to put the steam turbine bypass system back into operation. The first group of valves of the steam turbine bypass system can be unlocked through the manual locking control in the steam turbine bypass system, and then the pressure of the steam turbine bypass system can be controlled through the pressure setting module in the steam turbine bypass system to achieve the unlocking of the steam turbine bypass system.

[0087] Step S35 includes: controlling the opening of the inlet steam regulating valve and the steam inlet pipeline drain valve of the column under test. Specifically, in this step, it is intended to control the opening of the inlet steam regulating valve of the column under test, and then control the slow opening of the steam inlet pipeline drain valve of the column under test, so that the steam inlet pipeline drain valve can relieve the pressure of the steam inlet pipeline of the passive residual heat removal system column by column.

[0088] Step S36 includes: monitoring the pressure of the steam pipeline of the passive residual heat removal system, and when the steam pipeline pressure is less than the third set pressure value, controlling the sequential closing of the inlet steam regulating valve of the column under test and the passive residual heat removal system drain valve. Among them, the third set pressure value can be 0.05 MPa.g. The purpose of this step is to restore the column under test to the normal operating condition.

[0089] Step S36 includes: controlling the water replenishment of the condenser of the column under test to keep the liquid level of the condenser of the column under test within the fifth set liquid level range, and then controlling the sequential closing of the return pipeline water filling isolation valve, the demineralized water replenishment isolation valve of the ASP system water tank, and the condenser drain isolation valve in the passive residual heat removal system. Among them, the fifth set liquid level range can be from 3.7 m to 4.0 m. The purpose of this step is to keep the condenser within the standard range to meet the normal operation requirements of the nuclear power plant. The demineralized water replenishment isolation valve of the ASP system water tank refers to the isolation valve for demineralized water to replenish the water tank of the passive residual heat removal system.

[0090] Step S37 includes: controlling the opening of the nitrogen filling isolation valve of the column under test, and controlling the closing of the nitrogen filling isolation valve after the fourth set time. Among them, the fourth set time can be 5 min. The purpose of this step is to conduct nitrogen purging of the inlet steam pipeline of the passive residual heat removal system for the fourth set time to achieve the purpose of cleaning the inlet steam pipeline and avoid foreign objects entering the unit during the test process.

[0091] Step S38 includes: when the steam pipeline pressure enters the third set pressure range, controlling the system pipeline nitrogen filling isolation valve in the passive residual heat removal system to close and standing still for the fifth set time. Among them, the third set pressure range can be 0.05 MPa.g to 0.1 MPa.g, and the fifth set time can be 10 min. The steam pipeline pressure can be measured by the steam pipeline pressure gauge (an existing device) of the tested train. The purpose of this step is to ensure that the steam pipeline pressure returns to the normal state.

[0092] Step S39 includes: controlling the liquid level of the collection tank in the passive residual heat removal system to be within the third set liquid level range and the liquid temperature of the collection tank to be within the second set temperature range. Among them, the third set liquid level range can be 6.3 m to 6.6 m, and the second set temperature range can be 5 °C to 50 °C. The purpose of this step is to ensure that the liquid level and liquid level stability of the collection tank return to the normal state.

[0093] Since some equipment in the HPR1000 unit needs to be in an inoperative state during the test steps, there is a certain risk to the safety of the nuclear power plant. To avoid the abnormal situation from intensifying or not being dealt with in a timely manner due to the abnormality of the HPR1000 unit during the test steps, in one embodiment, the test steps may further include: determining whether the HPR1000 unit has an abnormality; when the HPR1000 unit has an abnormality, resetting the start signal of the passive residual heat removal system through the manual reset control in the passive residual heat removal system, and sequentially closing the reflux isolation valve, the inlet steam isolation valve, and the inlet steam regulating valve of the tested train; controlling the opening of the feed water isolation valves in the three steam generators and the opening of the feed water isolation valves in the three steam generators; controlling the blowdown of the three steam generators; and adjusting the letdown pressure of the volume control system in the HPR1000 unit according to the operation.

[0094] Specifically, the criteria for determining whether the HPR1000 unit has an abnormality may include: the reactor protection signal is not triggered after the protection function of the passive residual heat removal system is triggered for the second set time, there are valves (the valves include the inlet steam isolation valve, the inlet steam regulating valve of the tested train, the feed water pipeline isolation valve of the steam generator, etc.) that cannot perform correct actions according to the control, the average temperature of the primary loop is not within the first set temperature range, the pressure of the primary loop is not within the first set pressure range, the liquid level of the pressurizer is not within the first set liquid level range, the pressures of the three steam generators are not within the second set pressure range, and the liquid levels of the three steam generators are not within the second set liquid level range, etc.; as long as any of the above criteria is met, it can be determined that the HPR1000 unit has an abnormality.

[0095] Affected by external factors (such as weather, etc.), the temperature of the steam inlet pipeline of the main steam discharge system may be relatively low, which affects the test accuracy. Therefore, in one embodiment, such asFigure 1 As shown, a warm-up pipe step may also be included between the preparation step and the test step.

[0096] Warm-up pipe step: Control the opening of the main steam pipe drain valve in the HPR1000 unit and put into operation the drain pipeline of the main steam discharge system in the HPR1000 unit; control the opening of the inlet steam isolation valve of the test column and control the opening of the inlet steam regulating valve of the test column to the second set opening; continuously obtain the steam inlet pipeline pressure and the main pipe pressure of the main steam discharge system. When the steam inlet pipeline pressure rises to be close to or equal to the main pipe pressure, control the inlet steam regulating valve of the test column to be fully open, and close the inlet steam isolation valve and the inlet steam regulating valve of the test column after the sixth set time; determine whether the main steam discharge system triggers the main valve condensation risk alarm. If not, control the closing of the main steam pipe drain valve and isolate the drain pipeline of the main steam discharge system; determine whether the liquid level of the condenser of the test column is not within the seventh set liquid level range. If so, control the liquid level of the condenser of the test column to be maintained within the seventh set liquid level range (for example, when the liquid level is too high, open the drain valve of the condenser, and when the liquid level is too low, open the makeup water valve of the condenser). Among them, the second set opening can be 5%, the sixth set time can be 5 min, and the seventh set liquid level range can be from 3.7 m to 4.0 m.

[0097] Furthermore, during the warm-up pipe step, if the temperature of the primary circuit rises to the third set temperature and the temperature still has an upward trend, control one of the main pumps (preferably the No. 1 main pump RCP1110PO of the HPR1000 unit) to stop operating, and keep the pressure of the steam atmosphere discharge system at about the fourth set pressure to prevent the temperature of the steam inlet pipeline from continuing to rise and exceeding the safety range; after the warm-up pipe step is completed, control the stopped main pump to resume starting. Among them, the third set temperature can be 296 °C, and the fourth set pressure can be 8.5 MPa.g.

[0098] In one embodiment, the test data includes the average temperature change data of the primary loop, the pressure change data of the primary loop, the level change data of the pressurizer, the pressure change data of the three steam generators, and the level change data of the three steam generators continuously monitored from the moment when the protection function of the passive residual heat removal system is triggered until the duration reaches the first set time or the average temperature of the primary loop drops to the set temperature value. Correspondingly, the steps for determining whether the cooling performance of the tested train meets the set requirements based on the test data may include: fitting the test change curves of the respective change data according to the test data to obtain the primary loop average temperature curve, the primary loop pressure curve, the pressurizer level curve, the steam generator pressure curve, and the steam generator level curve, and determining whether the primary loop average temperature curve, the primary loop pressure curve, the pressurizer level curve, the steam generator pressure curve, and the steam generator level curve are respectively enveloped by the corresponding acceptance curves. When the primary loop average temperature curve, the primary loop pressure curve, the pressurizer level curve, the steam generator pressure curve, and the steam generator level curve are all enveloped by the corresponding acceptance curves, it is determined that the cooling performance of the tested train meets the set requirements. If any one of the primary loop average temperature curve, the primary loop pressure curve, the pressurizer level curve, the steam generator pressure curve, and the steam generator level curve is not enveloped by the corresponding acceptance curve, it is determined that the cooling performance of the tested train does not meet the set requirements. It can be understood that the acceptance curves corresponding to different test change curves are different, and the acceptance curves can be automatically designed by the staff according to the requirements.

[0099] Taking the primary loop average temperature curve as an example, analyzing the primary loop average temperature curve and the corresponding acceptance curve. When, at the same time coordinate, the proportion of the temperature coordinate of the primary loop average temperature curve that is less than the temperature coordinate of the acceptance curve is greater than the set percentage, it is determined that the primary loop average temperature curve is enveloped by the corresponding acceptance curve. Further, obtain n (n is a natural number greater than 1) time coordinates (which can be set in advance); determine the temperature coordinates corresponding to the n time coordinate points on the primary loop average temperature curve to obtain n average temperature sampling points; determine the temperature coordinates corresponding to the n time coordinate points on the acceptance curve to obtain n acceptance temperature coordinates; compare the sizes of the average temperature sampling points and the acceptance temperature coordinates with the same time coordinate, and calculate the number of average temperature sampling points that are less than the acceptance temperature coordinates to obtain the number m; calculate the quotient of m divided by n to obtain the proportion of the temperature coordinate of the primary loop average temperature curve that is less than the temperature coordinate of the acceptance curve. It is easy to understand that for whether the remaining change curves are enveloped by the corresponding acceptance curves, reference can be made to the above embodiments, and details will not be elaborated here.

[0100] To simplify the test process, in one embodiment, the column to be tested is preferably column C, which has the worst theoretical cooling performance among columns A, B, and C. It should be noted that since the on-site pipeline of column C is the longest and has the greatest resistance, its theoretical cooling performance is the worst. Understandably, if the cooling performance of column C is qualified, columns A and B are theoretically also qualified, that is, when the cooling performance of column C is qualified, it is determined that the cooling performance of the passive residual heat removal system meets the set requirements.

[0101] In another embodiment, the method for verifying the cooling performance of the passive residual heat removal system may further include: after each test on the column to be tested is completed, select one column from the untested columns as the new column to be tested, and sequentially execute the preparation step, the test step, and the unit restoration step based on the new column to be tested until all columns A, B, and C have been tested. When the cooling performances of columns A, B, and C are all qualified, it is determined that the cooling performance of the passive residual heat removal system meets the set requirements. It can be understood that this embodiment helps to improve the test accuracy, but the test process is relatively complex and takes relatively long time.

[0102] To reduce the risks during the test process, in one embodiment, the method for verifying the cooling performance of the passive residual heat removal system includes a risk analysis step.

[0103] The risk analysis step includes: during the test step, monitor the pressure of the primary loop. When the pressure of the primary loop is less than the fifth set pressure (which can be 12.9 MPa.g), control the reactor protection signals of the reactor protection system and the reactor diversity drive protection system to take effect through the main control room control device, and block the safety injection signal triggered when the pressure of the primary loop pressurizer is less than the low 3 alarm level; before executing the test step, block the alarm signals of the pressure drops of the steam generators corresponding to columns A, B, and C being greater than the high 1 alarm level and the high 0 alarm level to avoid triggering the reactor trip signal; before executing the test step, control the drain valve of the main steam discharge pipeline to open, and slowly open the drain valve of the passive residual heat removal system for pressure relief and drainage to avoid internal leakage of the inlet steam isolation valve of the passive residual heat removal system; after the test step is completed, before opening the main steam pipeline isolation valve, warm up and drain the main valve to avoid water hammer after the main steam pipeline isolation valve is opened; before executing the preparation step, establish an isolation area at the top opening of the condensate tank, the test-related pipelines, supports, and temporary supports to prevent personnel from entering by mistake. Of course, the staff on the test site should wear earplugs, protective clothing, etc. to avoid scalding and hearing damage.

[0104] Understandably, the technical solution of the present invention can verify whether the cooling performance of the passive residual heat removal system meets the set requirements, so as to guide the subsequent HPR1000 unit to accurately and efficiently conduct heat conduction of the reactor core in the event of a severe DEC accident, which helps to accelerate the maintenance progress of the passive residual heat removal system during major overhauls and improve the economic benefits of the unit.

[0105] In this specification, each embodiment is described in a progressive manner. The key point of each embodiment is to illustrate the differences from other embodiments. For the same or similar parts among the embodiments, reference can be made to each other. For the devices disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple, and reference can be made to the description in the method part for related parts.

[0106] Those skilled in the art can further realize that the units and algorithm steps of each example described in combination with the embodiments disclosed in this article can be implemented by electronic hardware, computer software, or a combination of the two. To clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described according to functions in the above description. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of the present invention.

[0107] The steps of the methods or algorithms described in combination with the embodiments disclosed in this article can be directly implemented by hardware, software modules executed by a processor, or a combination of the two. The software modules can be placed in a random access memory (RAM), internal memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium well-known in the technical field.

[0108] It can be understood that the above embodiments only represent the preferred implementation modes of the present invention, and the description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, the above technical features can be freely combined, and several deformations and improvements can also be made, which all belong to the protection scope of the present invention. Therefore, all equivalent transformations and modifications made to the scope of the claims of the present invention should fall within the scope covered by the claims of the present invention.

Claims

1. A method for verifying the cooling performance of a passive residual heat removal system, which is used for the HPR1000 unit. The HPR1000 unit includes a passive residual heat removal system, a primary loop, a pressurizer, and three steam generators, and is characterized in that, The method includes: Preparation step: controlling the HPR1000 unit so that the average temperature of the primary circuit is maintained within a first set temperature range, the pressure of the primary circuit is maintained within a first set pressure range, the liquid level of the pressurizer is maintained within a first set liquid level range, the pressures of the three steam generators are maintained within a second set pressure range, and the liquid levels of the three steam generators are maintained within a second set liquid level range, and the heat of the primary circuit can only be discharged through the passive waste heat removal system; Test steps: triggering the protection function of the passive waste heat removal system to allow the heat of the first circuit to be discharged through the condenser of the tested column in the passive waste heat removal system; recording the duration of the waste heat discharge of the condenser of the tested column, and simultaneously continuously monitoring the average temperature of the first circuit, the pressure of the first circuit, the liquid level of the regulator, the pressure of the three steam generators and the liquid level of the three steam generators until the duration reaches a first set time or the average temperature of the first circuit drops to a set temperature value, so as to obtain test data; determining whether the cooling performance of the tested column meets the set requirements based on the test data.

2. The method for verifying the cooling performance of the passive residual heat removal system according to claim 1, wherein In the preparation step, the controlling the HPR1000 unit includes: Control the HPR1000 unit to be in a hot shutdown condition, control the proportional heater in the HPR1000 unit and the operator auxiliary functions related to the primary circuit pressure control to be put into operation, and set the average temperature of the primary circuit to a set temperature value and the pressure of the primary circuit to a first set pressure value, so that the average temperature of the primary circuit is maintained within a first set temperature range and the pressure of the primary circuit is maintained within a first set pressure range; Controlling the pressurizer to be in an automatic control mode, putting the pressurizer liquid level control-related operator auxiliary protection function into operation, and setting the liquid level of the pressurizer to a first set liquid level value, so that the liquid level of the pressurizer is maintained within the first set liquid level range; Controlling the operation of the charging pump and three main pumps in the HPR1000 unit, setting the three steam generators to the automatic control mode and putting the sewage discharge functions of the three steam generators into operation, and setting the liquid levels of the three steam generators to the second set liquid level value, so that the liquid levels of the three steam generators are maintained within the second set liquid level range; Controlling the main steam pipeline isolation valve in the HPR1000 unit to open, setting the turbine bypass system in the HPR1000 unit to a pressure control mode, and setting the pressures of the three steam generators to a second set pressure value, so that the pressures of the three steam generators are maintained within the second set pressure range; Control the main steam release isolation valve of the steam atmosphere discharge system in the HPR1000 unit to be closed, control the opening of the main steam release control valve of the steam atmosphere discharge system to be set to a first set opening, control the emergency water supply system in the HPR1000 unit to be shut down, control the isolation of the primary and secondary loop sampling pipelines in the HPR1000 unit, isolate the coolant storage tank downflow pipeline between the volume control system and the reactor coolant treatment system in the HPR1000 unit, control the inlet steam isolation valve, inlet steam regulating valve and reflux isolation valve of the tested column to be in the working position, control the inlet steam isolation valve, inlet steam regulating valve and reflux isolation valve of all other columns in the HPR1000 unit except the tested column to be in the isolation position, so that the condenser of the tested column in the passive residual heat removal system can only export residual heat through the preset tested column.

3. The method for verifying the cooling performance of the passive residual heat removal system according to claim 2, characterized in that, The controlling of the HPR1000 unit further comprises: The liquid level of the water collecting tank in the passive waste heat removal system is controlled to be maintained within the third set liquid level range, the liquid temperature of the water collecting tank is controlled to be maintained within the second set temperature range, and the liquid level of the condenser of the tested column is controlled to be maintained within the fourth set liquid level range.

4. The passive residual heat removal system cooling performance verification method according to claim 3, characterized in that The first set temperature range is 293℃ to 297℃, the first set pressure range is 15.3MPa.g to 15.5MPa, the first set liquid level range is 34% to 38%, the second set pressure range is 7.8MPa.g to 8.0MPa.g, the second set liquid level range is 48% to 52%, the third set liquid level range is 6.3m to 6.6m, the second set temperature range is 5℃ to 50℃, and the fourth set liquid level range is 3.7m to 4.0m.

5. The method for verifying the cooling performance of the passive residual heat removal system according to claim 2, characterized in that, The controlling of the HPR1000 unit further comprises: The HPR1000 unit is placed in a temporary control change condition so that the protection functions of the HPR1000 unit except the protection function of the passive residual heat removal system are locked, and the diesel engine start signal in the plant power failure condition is not triggered.

6. The method for verifying the cooling performance of the passive residual heat removal system according to claim 1, characterized in that The first set time is 30 minutes; and / or the set temperature value is 285°C.

7. The method for verifying the cooling performance of the passive residual heat removal system according to claim 1, characterized in that In the test step, triggering the protection function of the passive residual heat removal system so that the heat of the primary circuit is discharged through the condenser of the tested column in the passive residual heat removal system includes: The pressure controller of the pressurizer is set to manual mode, the on-off heater in the HPR1000 unit is set to automatic control mode, the isolation valves of the water supply pipelines of the three steam generators are controlled to be closed, and then the protection function of the passive waste heat removal system is triggered; After the protection function of the passive residual heat removal system is triggered for a second set time, determine whether the reactor protection signal of the passive residual heat removal system is triggered. If so, control the inlet steam isolation valve and the inlet steam regulating valve of the tested train to open, close the main valves of the three main steam discharge systems in the HPR1000 unit, and close the blowdown isolation valve of the steam generator blowdown system in the HPR1000 unit; After the protection function of the passive residual heat removal system is triggered for a third set time, control the reflux isolation valve of the tested train to open and control the turbine bypass system in the HPR1000 unit to be blocked.

8. The method for verifying the cooling performance of the passive residual heat removal system according to claim 7, characterized in that, After the test step, it further includes: Unit recovery step: Control the blowdown isolation valve of the steam generator blowdown system to open; Set the pressure controller to the automatic control mode, and set the proportional heater and the on-off heater in the HPR1000 unit to the automatic control mode; Control the feed water line isolation valves of the three steam generators to open; Control the turbine bypass system to be unlocked; Control the inlet steam regulating valve and the steam inlet pipeline drain valve of the tested train to open; Monitor the steam pipeline pressure of the passive residual heat removal system, and when the steam pipeline pressure is less than the third set pressure value, control the inlet steam regulating valve of the tested train and the passive residual heat removal system drain valve to close in sequence; Control the condenser of the tested train to be replenished with water so that the liquid level of the condenser of the tested train is maintained within the fifth set liquid level range, and then control the reflux pipeline filling isolation valve, the demineralized water replenishing isolation valve of the ASP system water tank, and the condenser drain isolation valve in the passive residual heat removal system to close in sequence; Control the nitrogen filling isolation valve of the tested train to open and control the nitrogen filling isolation valve to close after the fourth set time; When the steam pipeline pressure enters the third set pressure range, control the system pipeline nitrogen filling isolation valve in the passive residual heat removal system to close and stand for the fifth set time.

9. The method for verifying the cooling performance of the passive residual heat removal system according to claim 8, wherein In the test step, it further includes: Determine whether the HPR1000 unit has an abnormality; When the HPR1000 unit has an abnormality, reset the start signal of the passive residual heat removal system through the manual reset control in the passive residual heat removal system, close the reflux isolation valve, the inlet steam isolation valve, and the inlet steam regulating valve of the tested train in sequence; control the feed water isolation valves in the three steam generators to open, and control the three steam generators to blow down; and adjust the letdown pressure of the volume control system in the HPR1000 unit according to the operation.

10. The method for verifying the cooling performance of the passive residual heat removal system according to any one of claims 1 to 8, characterized in that, Between the preparation step and the test step, it further includes: Warm-up pipe steps: Control the opening of the main steam pipeline drain valve in the HPR1000 unit, and put into operation the drain pipeline of the main steam discharge system in the HPR1000 unit; Control the opening of the inlet steam isolation valve of the test column and control the opening of the inlet steam regulating valve of the test column to the second set opening. Continuously obtain the steam inlet pipeline pressure and the main pipe pressure of the main steam discharge system. When the steam inlet pipeline pressure rises to be close to or equal to the main pipe pressure, control the inlet steam regulating valve of the test column to be fully open, and close the inlet steam isolation valve and the inlet steam regulating valve of the test column after the sixth set time; Determine whether the main steam discharge system triggers the main valve condensation risk alarm. If not, control the closing of the main steam pipeline drain valve and isolate the drain pipeline of the main steam discharge system; Determine whether the liquid level of the condenser of the test column is not within the seventh set liquid level range. If so, control the liquid level of the condenser of the test column to be maintained within the seventh set liquid level range.

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