Method for calculating heat exchange capacity of secondary side passive residual heat removal system

Abstract

The invention discloses a method for calculating the heat exchange capacity of a secondary side passive residual heat removal system, the secondary side passive residual heat removal system is applied to a nuclear power station unit, the system comprises a cooling water tank and a condenser soaked in the cooling water tank, a water supply valve is arranged on the cooling water tank, the cooling water tank is connected with a water supply tank through the water supply valve, and the condenser is connected with the water supply tank. The condenser is connected with a steam generator, and a steam exhaust valve is arranged between the steam generator and the condenser; according to the heat conduction efficiency testing method, within the testing time delta t, steam generated by a steam generator is fed into a condenser, water in a cooling water tank absorbs heat emitted by the condenser to be evaporated, then water is supplied to the cooling water tank through a water supply tank, it is ensured that the liquid level of the cooling water tank is kept consistent before and after testing, and finally the heat conduction efficiency is tested through the water amount V consumed by the water supply tank. And calculating to obtain the heat conduction efficiency Q of the system. The invention provides a method for calculating the heat exchange capacity of a secondary side passive residual heat removal system through the liquid level change of a water supply tank, and solves the existing technical problems.

Description

Technical Field

[0001] This application relates to the field of nuclear power plant unit testing, and particularly to a method for calculating the heat transfer capacity of the passive residual heat removal system on the secondary side. Background Art

[0002] The passive residual heat removal system (ASP) on the secondary side mainly performs the heat conduction function under accident conditions beyond the design basis (DEC). Its applicable conditions are accident conditions where the emergency feedwater system (ASG) needs to be put into operation to remove the heat in the primary loop but the emergency feedwater system fails. In this accident condition, the passive residual heat removal system on the secondary side is activated to remove the heat in the primary loop. Therefore, the passive residual heat removal system on the secondary side is one of the guarantees for the safe operation of nuclear power plant units.

[0003] The natural circulation test of the passive residual heat removal system on the secondary side is an important test. Its purpose is to verify whether natural circulation can be established after the passive residual heat removal system on the secondary side is put into operation and whether the heat conduction capacity after the establishment of natural circulation can meet the design requirements. Therefore, it is necessary to conduct special analysis and research on the passive residual heat removal system on the secondary side and formulate an implementation plan for its natural circulation test.

[0004] Currently, to calculate the heat conduction of a general system, it is necessary to first measure the flow rate of the system and then convert it into heat conduction through formula calculation. However, in order to establish natural circulation smoothly in the current passive residual heat removal system on the secondary side, the design of the pipes in the passive residual heat removal system on the secondary side should minimize the pipe resistance. Therefore, the passive residual heat removal system on the secondary side is not equipped with a flow orifice plate and a flowmeter, and the flow rate of the system cannot be accurately measured. Furthermore, the heat conduction of the system cannot be calculated through the enthalpy difference and the flow rate.

[0005] Therefore, it is necessary to design a method that can be used to calculate the heat conduction efficiency of the passive residual heat removal system on the secondary side. Summary of the Invention

[0006] In order to solve one of the technical problems existing in the prior art, this application provides a method for calculating the heat transfer capacity of the passive residual heat removal system on the secondary side, which can calculate the heat transfer capacity of the passive residual heat removal system on the secondary side.

[0007] A method for calculating the heat transfer capacity of a secondary-side passive residual heat removal system provided according to some embodiments of the present application. The secondary-side passive residual heat removal system is applied to a nuclear power plant unit. The secondary-side passive residual heat removal system includes at least one cooling water tank and a condenser immersed in the cooling water tank. A water supply valve is provided on the cooling water tank. The cooling water tank is connected to a water supply tank through the water supply valve. The condenser is connected to a steam generator, and an exhaust valve is provided between the steam generator and the condenser. Among them, in the heat conduction efficiency test method, within the test time Δt, the steam generated by the steam generator is sent into the condenser, so that the water in the cooling water tank absorbs the heat dissipated by the condenser and evaporates. Then, water is supplied to the cooling water tank through the water supply tank to ensure that the liquid level of the cooling water tank remains the same before and after the test. Finally, the heat conduction efficiency Q of the system is calculated through the water consumption V of the water supply tank.

[0008] In some embodiments, the calculation formula for the heat conduction efficiency Q is:

[0009]

[0010] Where H1 is the enthalpy value of the saturated steam of the steam generator at the corresponding pressure, H2 is the enthalpy value of the water at this state recorded by querying the thermodynamic parameters table of water and water vapor according to the water temperature of the water supply tank, V is the water consumption of the water supply tank, ρ 水 is the density of the water stored in the water supply tank, and Δt is the test time.

[0011] In some embodiments, the calculation formula for the water consumption V of the water supply tank is:

[0012] V = (h1 - h2) * S (2)

[0013] Where h1 is the initial liquid level of the water supply tank, h2 is the end liquid level of the water supply tank, and S is the cross-sectional area of the water supply tank.

[0014] In some embodiments, the method for testing the heat conduction efficiency specifically includes the following specific steps: S1. Record the initial liquid level h1 of the water supply water tank; S2. Open the exhaust valve to allow the steam generated by the steam generator to flow into the condenser, and the water in the cooling water tank absorbs the heat dissipated by the condenser and evaporates; S3. After a set test time Δt, close the exhaust valve; S4. Open the water supply valve to supply water from the water supply water tank to the cooling water tank until the liquid level of the cooling water tank rises to the same level as before the test, then close the water supply valve and record the final liquid level h2 of the water supply water tank; S5. Calculate the water consumption V of the water supply water tank through Formula 2; S6. Calculate the heat conduction efficiency Q through Formula 1. Through the above steps S1 to S6, the heat conduction efficiency Q of the secondary side passive residual heat removal system can be accurately calculated, so as to detect whether the secondary side passive residual heat removal system can meet the standard.

[0015] In some embodiments, the test time Δt is 30 min - 60 min. The design of the secondary side passive residual heat removal system is to meet the requirement of discharging the primary loop heat within 6 hours after an accident without considering the makeup water of the external system. However, when performing the commissioning test, considering control factors such as the test window arrangement and the unit status, it is impossible to fully execute according to 6 hours; to ensure the stability of the test data, the test time cannot be too short; after comprehensive evaluation, it is considered that the test duration of 30 min - 60 min can collect sufficient test data to determine the test results and meet the project duration requirements during the engineering commissioning stage.

[0016] In some embodiments, the test time Δt is 40 min to obtain the best test effect.

[0017] In some embodiments, after calculating the heat conduction efficiency Q, it further includes step S7 of performing a natural circulation test on the secondary side passive residual heat removal system: S7. Isolate the inlet and outlet pipelines of the steam generator and other steam discharge pipelines, and keep the steam generator and the condenser connected according to the system design requirements, that is, put the secondary side passive residual heat removal system into operation, confirm that the steam isolation valve and the condensate return isolation valve are opened within the required time, monitor and record the change trends of the temperature and pressure parameters in the loop, as well as the change trend of the cooling water temperature in the cooling water tank, and draw the actual parameter change curve; after the test execution time reaches the preset time T, isolate the natural circulation test of the secondary side passive residual heat removal system and restore the steam generator to its initial state. By performing a natural circulation test on the secondary side passive residual heat removal system, it is ensured that the secondary side passive residual heat removal system can smoothly perform natural circulation after being put into operation, thus ensuring the reliability of the secondary side passive residual heat removal system.

[0018] In some embodiments, the preset time T is 30 min - 120 min. The design of the secondary-side passive residual heat removal system is such that without considering the makeup water of the external system, it can meet the requirement of discharging the heat of the primary circuit within 6 hours after an accident. However, when conducting commissioning tests, considering control factors such as the test window arrangement and the unit status, it is impossible to execute exactly according to 6 hours. To ensure the stability of the test data, the test time cannot be too short. After comprehensive evaluation, it is considered that sufficient test data can be collected for determining the test results and meeting the project construction period requirements during the engineering commissioning phase with a natural circulation test lasting for 30 min - 120 min.

[0019] In some embodiments, the preset time T is 40 min to obtain the best test effect.

[0020] In some embodiments, a first temperature sensor and a pressure sensor are arranged inside the steam generator. The first temperature sensor is used to monitor the temperature change inside the steam generator, and the pressure sensor is used to monitor the pressure change inside the steam generator.

[0021] In some embodiments, a second temperature sensor is arranged inside the cooling water tank to monitor the temperature change inside the cooling water tank.

[0022] In some embodiments, the water supply tank is the tank in the auxiliary feedwater system. The auxiliary feedwater system in the nuclear power plant unit supplies water to the cooling water tank of the secondary-side passive residual heat removal system, facilitating the linkage of the system.

[0023] In some embodiments, a liquid level sensor is arranged inside the water supply tank, and the initial liquid level h1 and the end liquid level h2 of the water supply tank can be conveniently obtained through the liquid level sensor.

[0024] In some embodiments, the secondary-side passive residual heat removal system includes three condensers, and each condenser is respectively connected to the steam generator.

[0025] In some embodiments, a transfer pump is arranged between the steam generator and the condenser.

[0026] The beneficial effects of the present application include:

[0027] The present application proposes a method for calculating the heat conduction efficiency of the secondary-side passive residual heat removal system through the liquid level change of the water supply tank, solving the problem that the heat conduction efficiency of the secondary-side passive residual heat removal system cannot be calculated because the flow rate of the secondary-side passive residual heat removal system cannot be measured.

[0028] Other features and advantages of the present application will be set forth in the following description, and in part will be obvious from the description, or may be learned by practice of the present application. The objectives and other advantages of the present application may be realized and attained by the structure particularly pointed out in the specification, claims and drawings. Description of the Drawings

[0029] To describe the technical solution of the present application more clearly, the present application will be further described below in conjunction with the drawings and embodiments. It should be understood that the following drawings only show some embodiments of the present application, and thus should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts. In the drawings:

[0030] Figure 1 is a schematic structural diagram of the secondary-side passive residual heat removal system provided by the present application;

[0031] Figure 2 is a graph showing the changing trend of temperature parameters in the primary circuit of a nuclear power plant;

[0032] Figure 3 is a graph showing the changing trend of pressure parameters in the primary circuit of a nuclear power plant. Detailed Embodiments

[0033] The present application will be further described in detail below in conjunction with the drawings through specific embodiments. Similar elements in different embodiments are labeled with related similar element numbers. In the following embodiments, many detailed descriptions are provided to enable a better understanding of the present application. However, those skilled in the art can easily recognize that some of the features can be omitted in different situations, or can be replaced by other elements, materials, or methods. In some cases, some operations related to the present application are not shown or described in the specification to avoid overwhelming the core part of the present application with excessive descriptions. For those skilled in the art, it is not necessary to describe these related operations in detail, and they can fully understand the related operations based on the description in the specification and general technical knowledge in the art.

[0034] In addition, the features, operations, or characteristics described in the specification can be combined in any appropriate manner to form various embodiments. At the same time, the steps or actions in the method description can also be reordered or adjusted in a manner obvious to those skilled in the art. Therefore, the various sequences in the specification and drawings are only for clearly describing a certain embodiment and do not mean a necessary sequence, unless it is stated that a certain sequence must be followed.

[0035] The serial numbers assigned to the components in this text itself, such as "first", "second", etc., are only used to distinguish the described objects and do not have any sequential or technical meaning. And for the terms "connection" and "coupling" mentioned in this application, unless otherwise specified, both include direct and indirect connection (coupling).

[0036] Generally speaking, in the passive residual heat removal system on the secondary side of a nuclear power plant unit, in order to smoothly establish natural circulation, the design of the pipeline should minimize the pipe resistance. Therefore, the passive residual heat removal system on the secondary side is not equipped with a flow orifice plate and a flowmeter, and it is impossible to calculate the heat conduction capacity of the passive residual heat removal system on the secondary side through enthalpy difference and flow rate.

[0037] The following combines Figures 1 to 3 with the provided embodiments to further elaborate on the method for calculating the heat transfer capacity of the passive residual heat removal system on the secondary side proposed in this application.

[0038] The embodiments of this application provide a method for calculating the heat transfer capacity of the passive residual heat removal system on the secondary side. As Figure 1 shown, the passive residual heat removal system on the secondary side is applied to a nuclear power plant unit. The passive residual heat removal system on the secondary side includes at least one cooling water tank 20 and a condenser 30 immersed in the cooling water tank 20. A water supply valve is provided on the cooling water tank 20. The cooling water tank 20 is connected to a water supply tank through the water supply valve. The condenser 30 is connected to the steam generator 10, and an exhaust valve is provided between the steam generator 10 and the condenser 30. Among them, the heat conduction efficiency test method requires that within the test time Δt, the steam generated by the steam generator 10 is sent into the condenser 30, so that the water in the cooling water tank 20 absorbs the heat dissipated by the condenser 30 and evaporates. Then, water is supplied to the cooling water tank through the water supply tank to ensure that the liquid level of the cooling water tank remains the same before and after the test. Finally, the heat conduction efficiency Q of the system is calculated through the water consumption V of the water supply tank. This application proposes a method for calculating the heat conduction efficiency of the passive residual heat removal system on the secondary side through the liquid level change of the water supply tank, which solves the problem that the heat conduction efficiency of the passive residual heat removal system on the secondary side cannot be calculated because the flow rate of the passive residual heat removal system on the secondary side cannot be measured.

[0039] Furthermore, in some embodiments, the formula used to calculate the heat conduction efficiency Q is as follows:

[0040]

[0041] where H1 is the enthalpy value of the saturated steam in the steam generator at the corresponding pressure, and H2 is the enthalpy value of the water at this state recorded by querying the thermodynamic parameters table of water and water vapor according to the water temperature of the water supply tank. That is, H1 and H2 can be obtained by querying the corresponding enthalpy values through the internal pressure of the steam generator and the water temperature of the water supply tank; V is the water consumption of the water supply tank, ρ 水ρ is the density of the water stored in the water supply tank, and Δt is the test time.

[0042] The above formula 1 uses the calculation results of the water consumption V of the water supply tank and the test time Δt to replace the flow rate of the secondary side passive residual heat removal system, so as to calculate the value of the heat conduction efficiency Q.

[0043] Further, in some embodiments, the formula used to calculate the water consumption V of the water supply tank is:

[0044] V = (h1 - h2) * S; (2)

[0045] Wherein, h1 is the initial liquid level before the water supply tank starts to supply water, h2 is the end liquid level after the water supply tank finishes supplying water, and S is the cross-sectional area of the water supply tank.

[0046] The above formula 2 uses the initial liquid level h1 before the water supply tank starts to supply water, the end liquid level h2 after the water supply tank finishes supplying water, and the cross-sectional area S of the water supply tank to calculate the water consumption V of the water supply tank for supplementing formula 1.

[0047] Further, in some embodiments, the method for calculating the heat exchange capacity of the secondary side passive residual heat removal system of the present application specifically includes the following steps:

[0048] S1. Record the initial liquid level h1 of the water supply tank;

[0049] S2. Open the exhaust valve to allow the steam generated by the steam generator to flow into the condenser, and the water in the cooling water tank absorbs the heat dissipated by the condenser and evaporates;

[0050] S3. After a set test time Δt, close the exhaust valve;

[0051] S4. Open the water supply valve, supply water to the cooling water tank through the water supply tank until the liquid level of the cooling water tank rises to the same level as before the test, close the water supply valve, and record the end liquid level h2 of the water supply tank;

[0052] S5. Calculate the water consumption V of the water supply tank using formula 2;

[0053] S6. Calculate the heat conduction efficiency Q using formula 1.

[0054] Through the above steps 1 to 6, the heat conduction efficiency Q of the secondary side passive residual heat removal system can be accurately calculated, so as to detect whether the secondary side passive residual heat removal system can meet the standards.

[0055] Further, in some embodiments, the test time Δt is 30 min - 60 min. The design of the secondary side passive residual heat removal system is such that, without considering external system make-up water, it can meet the requirement of discharging the primary loop heat within 6 hours after an accident. However, when conducting commissioning tests, considering control factors such as test window arrangements and unit status, it is impossible to execute exactly according to 6 hours. To ensure the smoothness of test data, the test time cannot be too short. After comprehensive evaluation, it is considered that sufficient test data can be collected for determining the test results with a test duration of 30 min - 60 min, and it also meets the project duration requirements during the engineering commissioning phase. Further still, in some embodiments, it is preferred to set the test time Δt to 40 min to achieve the best test effect.

[0056] Further, in some embodiments, after calculating the heat conduction efficiency Q, the following step S7 of the natural circulation test for the secondary side passive residual heat removal system is also required:

[0057] S7. Isolate the inlet and outlet pipelines of the steam generator 10 and other steam discharge pipelines. According to the system design requirements, keep the steam generator 10 and the condenser 30 connected, that is, put the secondary side passive residual heat removal system into operation. Confirm that the steam isolation valve and the condensate return isolation valve are opened within the required time, monitor and record the change trends of the temperature and pressure parameters in the loop, as Figure 2 and Figure 3 shown, and the change trend of the cooling water temperature in the cooling water tank 20, and draw the actual parameter change curve;

[0058] After the test execution time reaches the preset time T, isolate the natural circulation test of the secondary side passive residual heat removal system and restore the steam generator 10 to its initial state.

[0059] By conducting the natural circulation test on the secondary side passive residual heat removal system, it is ensured that after the secondary side passive residual heat removal system is put into operation, natural circulation can proceed smoothly, thus guaranteeing the reliability of the secondary side passive residual heat removal system.

[0060] Further, in some embodiments, the preset time T is 30 min - 120 min. The design of the secondary side passive residual heat removal system is such that, without considering external system make-up water, it can meet the requirement of discharging the primary loop heat within 6 hours after an accident. However, when conducting commissioning tests, considering control factors such as test window arrangements and unit status, it is impossible to execute exactly according to 6 hours. To ensure the smoothness of test data, the test time cannot be too short. After comprehensive evaluation, it is considered that sufficient test data can be collected for determining the test results with a natural circulation test duration of 30 min - 120 min, and it also meets the project duration requirements during the engineering commissioning phase.

[0061] Furthermore, in some embodiments, the preset time T is also 40 min to achieve the best test results.

[0062] In some embodiments, a first temperature sensor and a pressure sensor are disposed inside the steam generator 10. The first temperature sensor is used to monitor the temperature change inside the steam generator 10, and the pressure sensor is used to monitor the pressure change inside the steam generator 10.

[0063] In some embodiments, a second temperature sensor is disposed inside the cooling water tank 20 for monitoring the temperature change inside the cooling water tank 20.

[0064] In some embodiments, the water supply tank is a tank in the auxiliary feed water system. Water is supplied from the auxiliary feed water system in the nuclear power plant unit to the cooling water tank 20 of the secondary side passive residual heat removal system, facilitating the linkage of the system.

[0065] In some embodiments, a liquid level sensor is disposed inside the water supply tank. The initial liquid level h1 and the end liquid level h2 of the water supply tank can be conveniently obtained through the liquid level sensor.

[0066] In some embodiments, the secondary side passive residual heat removal system includes three condensers 30, and each condenser 30 is respectively connected to the steam generator 10. The three condensers 30 can provide three independent cooling circuits, effectively improving the efficiency of removing the residual heat of the system.

[0067] In some embodiments, a transfer pump is disposed between the steam generator 10 and the condenser 30, which can actively transfer the steam generated by the steam generator 10 into the condenser 30 to accelerate the process of removing the residual heat.

[0068] As Figure 2 and Figure 3 shown, in some embodiments, for the first natural circulation test of the secondary side passive residual heat removal system, the relevant results are as follows when implemented according to the above scheme in a unit of a nuclear power plant:

[0069] 1) Changes in the main parameters of the primary and secondary loops

[0070] The time when the condensate return isolation valve is fully open is selected as 0 min, and the time when the secondary side passive residual heat removal system exits operation is 39 min. The changes in the main parameters of the primary and secondary loops are recorded in Table 1 as follows.

[0071] Table 1 Main parameters of the primary and secondary loops during the test

[0072]

[0073] 2) Test results

[0074] After each column of the secondary-side passive residual heat removal system is put into operation separately, the temperatures and pressures of the primary and secondary circuits gradually decrease; at the same time, the temperature of the cooling water in the cooling water tank 20 gradually increases. From this, it can be judged that natural circulation can be established in each column of the secondary-side passive residual heat removal system, meeting the design requirements.

[0075] Through the heat transfer measurement test from the primary circuit to the secondary circuit, the heat conduction efficiency Q is obtained, and the temperature and pressure change curves of the primary and secondary circuits under the theoretical heat conduction capacity of the secondary-side passive residual heat removal system are plotted; at the same time, after the natural circulation test of the secondary-side passive residual heat removal system is completed, the temperatures and pressures of the primary and secondary circuits of the unit and their change trends with temperature are recorded, and the actual parameter change curves are plotted as specifically shown in Figure 2 and Figure 3 shown. After comparison, after the initial data fluctuations during the initial stage of the natural circulation establishment process of about 400 s, the secondary-side passive residual heat removal system operates stably in the subsequent operation stage. The actual curves obtained from the test are all below the theoretical curves. After the natural circulation of the unit is successfully established, the temperature and pressure drop rates of the primary and secondary circuits are greater than the theoretical drop rates, proving that the actual heat conduction capacity of the secondary-side passive residual heat removal system is greater than the design value, meeting the design requirements, and the test results are qualified.

[0076] It can be understood that the above embodiments only represent the preferred embodiments of the present application, and the description is relatively specific and detailed, but it cannot be construed as a limitation on the patent scope of the present application; it should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, 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 application; therefore, all equivalent transformations and modifications made to the scope of the claims of the present application should fall within the scope covered by the claims of the present application.

Claims

1. A method for calculating the heat transfer capacity of a secondary-side passive residual heat removal system, characterized in that The secondary passive residual heat removal system is applied to a nuclear power plant unit. The secondary passive residual heat removal system includes at least one cooling water tank and a condenser immersed in the cooling water tank. A water supply valve is arranged on the cooling water tank. The cooling water tank is connected to a water supply tank through the water supply valve. The condenser is connected to a steam generator. An exhaust valve is arranged between the steam generator and the condenser; Among them, in the heat conduction efficiency test method, within the test time Δt, the steam generated by the steam generator is sent into the condenser, so that the water in the cooling water tank absorbs the heat dissipated by the condenser and evaporates. Then, water is supplied to the cooling water tank through the water supply tank to ensure that the liquid level of the cooling water tank remains the same before and after the test. Finally, the heat conduction efficiency Q of the system is calculated through the water consumption V of the water supply tank.

2. The method for calculating the heat exchange capacity of the secondary-side passive residual heat removal system according to claim 1, wherein The calculation formula for the heat conduction efficiency Q is: where H1 is the enthalpy value of the saturated steam of the steam generator at the corresponding pressure, H2 is the enthalpy value of water at this state recorded by querying the thermodynamic parameter table of water and water vapor according to the water temperature of the water supply tank, V is the water consumption of the water supply tank, ρ 水 is the density of the water stored in the water supply tank, and Δt is the test time.

3. The method for calculating the heat exchange capacity of the secondary-side passive residual heat removal system according to claim 2, wherein The calculation formula for the water consumption V of the water supply tank is: V = (h1 - h2) * S; Among them, h1 is the initial liquid level of the water supply tank, h2 is the end liquid level of the water supply tank, and S is the cross-sectional area of the water supply tank.

4. The method for calculating the heat exchange capacity of the secondary-side passive residual heat removal system according to claim 3, wherein The heat conduction efficiency test method specifically includes the following steps: S1. Record the initial liquid level h1 of the water supply tank; S2. Open the exhaust valve to allow the steam generated by the steam generator to flow into the condenser, and the water in the cooling water tank absorbs the heat dissipated by the condenser and evaporates; S3. After the set test time Δt, close the exhaust valve; S4. Open the water supply valve, supply water to the cooling water tank through the water supply tank until the liquid level of the cooling water tank rises to the same level as before the test, close the water supply valve, and record the end liquid level h2 of the water supply tank; S5. Calculate the water consumption V of the water supply tank; S6. Calculate the heat conduction efficiency Q.

5. The method for calculating the heat exchange capacity of the secondary-side passive residual heat removal system according to claim 4, wherein The test time Δt is 30 min - 60 min.

6. The method for calculating the heat exchange capacity of the secondary-side passive residual heat removal system according to claim 5, wherein The test time Δt is 40 min.

7. The method for calculating the heat exchange capacity of the secondary-side passive residual heat removal system according to claim 4, wherein After calculating the heat conduction efficiency Q, it further includes step S7 of conducting a natural circulation test on the secondary passive residual heat removal system: S7. Isolate the inlet and outlet pipelines of the steam generator and other steam discharge pipelines. According to the system design requirements, keep the connection between the steam generator and the condenser, that is, put the secondary passive residual heat removal system into operation. Confirm that the steam isolation valve and the condensate return isolation valve are opened within the required time, monitor and record the change trends of the temperature and pressure parameters in the loop, as well as the change trend of the cooling water temperature in the cooling water tank, and draw the actual parameter change curve; After the test execution time reaches the preset time T, isolate the natural circulation test of the secondary passive residual heat removal system and restore the steam generator to its initial state.

8. The method for calculating the heat exchange capacity of the secondary-side passive residual heat removal system according to claim 7, wherein The preset time T is 30 min - 120 min.

9. The method for calculating the heat exchange capacity of the secondary-side passive residual heat removal system according to claim 8, wherein The preset time T is 40 min.

10. The method for calculating the heat exchange capacity of the secondary side passive residual heat removal system according to claim 7, wherein A first temperature sensor and a pressure sensor are arranged inside the steam generator.

11. The method for calculating the heat exchange capacity of the secondary side passive residual heat removal system according to claim 7, characterized in that, A second temperature sensor is arranged in the cooling water tank.

12. The method for calculating the heat exchange capacity of the secondary-side passive residual heat removal system according to any one of claims 1 to 11, characterized in that, The water supply tank is a tank in the auxiliary feed water system.

13. The method for calculating the heat exchange capacity of the secondary-side passive residual heat removal system according to claim 12, wherein, A liquid level sensor is arranged in the water supply tank.

14. The method for calculating the heat exchange capacity of the secondary-side passive residual heat removal system according to any one of claims 1 to 11, characterized in that The secondary passive residual heat removal system includes three condensers, and each condenser is respectively connected to the steam generator.

15. The method for calculating the heat exchange capacity of the secondary side passive residual heat removal system according to claim 14, wherein A transfer pump is arranged between the steam generator and the condenser.

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