Method for establishing a steam cavity in a nuclear power unit stabilizer

Abstract

The application provides a method for establishing a steam cavity of a stabilizer in a nuclear power unit, and the method comprises the following steps: when the stabilizer in a primary loop meets a preset condition, the coolant in the stabilizer is heated from an initial temperature to a preset temperature, and at the same time when the heating of the coolant in the stabilizer is started, deoxidizing is performed on the coolant in the stabilizer by adding a deoxidizing agent to make the coolant deoxidized to be qualified, and the stabilizer is filled with water to a water physical state under a preset pressure; the preset pressure in the stabilizer is increased to a target pressure, the coolant in the stabilizer is heated to a target temperature, and the liquid level of the coolant in the stabilizer is decreased to a target liquid level, so as to establish a target steam cavity. The preset condition comprises that the liquid level of the coolant in the stabilizer is a preset liquid level. The heating process of the coolant in the stabilizer, the water filling process of the stabilizer and the deoxidizing process are synchronously performed, so that the starting speed of the nuclear power unit is improved, and the operation cost of the nuclear power unit is reduced.

Description

Technical Field

[0001] This application belongs to the field of pressurizer steam cavity creation technology, specifically relating to a method for pressurizer steam cavity creation in nuclear power units. Background Technology

[0002] The pressurizer in the primary loop of a nuclear power unit plays a crucial role in pressure control. With a gas chamber present, the pressurizer provides more stable pressure control. During operation, the upper part of the pressurizer is a gas phase space, and the lower part is a liquid phase space. Establishing the gas chamber is a critical path operation during the nuclear power unit startup process, and the speed at which the pressurizer establishes the gas chamber directly affects the startup speed of the nuclear power unit.

[0003] However, existing pressurizers require a very long time to establish the steam chamber (e.g., up to 16 to 17 hours), which undoubtedly reduces the start-up speed of nuclear power units and increases their operating costs. Summary of the Invention

[0004] In view of this, the embodiments of this application aim to provide a method for establishing a steam chamber in a pressurizer of a nuclear power unit. By setting the heating process of the coolant in the pressurizer, the water filling process of the pressurizer, and the deoxygenation process to be carried out simultaneously, the start-up speed of the nuclear power unit is improved and the operating cost of the nuclear power unit is reduced.

[0005] This application provides a method for establishing a steam cavity in a pressurizer of a nuclear power unit. The method includes: when the pressurizer in the primary loop meets preset conditions, controlling the coolant in the pressurizer to heat from an initial temperature to a preset temperature; simultaneously, adding deoxygenating chemicals to the pressurizer to remove oxygen until deoxygenation is qualified; controlling the preset pressure in the pressurizer to rise to a target pressure; controlling the coolant in the pressurizer to heat to the target temperature; and controlling the coolant level in the pressurizer to drop to a target level, thereby establishing the target steam cavity. The preset conditions include a preset coolant level in the pressurizer, a preset level greater than 50% and less than 90%, a preset temperature greater than 100°C and less than the upper temperature limit set for high-temperature corrosion of the pressurizer body material, and a saturation temperature corresponding to the preset pressure greater than the preset temperature.

[0006] In the above scheme, by simultaneously heating the coolant in the pressurizer, adding deoxygenating chemicals to the pressurizer to remove oxygen until it meets the required level, and filling the pressurizer with water at a preset pressure until it reaches a solid water state, the entire heating process of the coolant in the pressurizer from its initial temperature to the preset temperature, the deoxygenation process of the pressurizer, and the water filling process of the pressurizer can be synchronized. This shortens the time for deoxygenation of the pressurizer and heating of the coolant to the preset temperature, which is beneficial to improving the start-up speed of the nuclear power unit and reducing the operating cost of the nuclear power unit.

[0007] In one specific embodiment of this application, the above-mentioned method of controlling the coolant in the voltage regulator to heat from the initial temperature to the preset temperature includes: inserting at least one electric heater into the voltage regulator, using at least one electric heater to heat the coolant in the voltage regulator from the initial temperature to the preset temperature, wherein the preset liquid level is greater than the liquid level that can just submerge at least one electric heater; if the voltage regulator fails to deoxygenate properly when the coolant in the voltage regulator is heated to the preset temperature, the temperature of the coolant in the voltage regulator is controlled not to exceed the upper temperature limit set by the voltage regulator body material due to high-temperature corrosion by adjusting the number of at least one electric heater.

[0008] In one specific embodiment of this application, the above-mentioned process of adding an oxygen-removing agent to the voltage regulator to remove oxygen until it meets the required standards includes: adding an oxygen-removing agent to the voltage regulator; continuously monitoring the dissolved oxygen concentration in the voltage regulator using a primary sampling system; sampling the concentration of the oxygen-removing agent in the voltage regulator using the sampling system; adding more oxygen-removing agent if the concentration of the oxygen-removing agent in the voltage regulator is less than 1.5 times the dissolved oxygen concentration; and confirming that the oxygen removal in the voltage regulator is qualified if the dissolved oxygen concentration in the voltage regulator is less than 100 ppb.

[0009] In one specific embodiment of this application, the above-mentioned filling of the pressure regulator to a water-solid state under a preset pressure includes: controlling the primary circuit to fill with water so that the coolant level in the pressure regulator rises from a preset level to a full level; and controlling the pressure in the pressure regulator to rise to a preset pressure by adjusting the flow rate of the primary circuit for filling and draining, so that the coolant in the pressure regulator is in a water-solid state.

[0010] In one specific embodiment of this application, the aforementioned control of the preset pressure in the pressure regulator to rise to the target pressure, the control of the coolant in the pressure regulator to heat to the target temperature, and the control of the coolant level in the pressure regulator to drop to the target level to establish a target vapor chamber includes: controlling the coolant in the pressure regulator to heat from the preset temperature to the saturation temperature corresponding to the preset pressure, and then controlling the coolant level in the pressure regulator to drop to the target level to establish an initial vapor chamber at the preset pressure; controlling the pressure in the pressure regulator to rise from the preset pressure to the target pressure, and controlling the coolant in the pressure regulator to continue heating from the saturation temperature corresponding to the preset pressure to the target temperature to establish a target vapor chamber at the target pressure.

[0011] In one specific embodiment of this application, after the coolant in the pressure regulator is heated from a preset temperature to the saturation temperature corresponding to the preset pressure, the coolant level in the pressure regulator is controlled to drop to the target level to establish an initial vapor chamber at the preset pressure. This includes: after the coolant in the pressure regulator is heated from a preset temperature to the saturation temperature corresponding to the preset pressure, stopping the primary circuit from filling with water and controlling the primary circuit to drain, so that the coolant level in the pressure regulator begins to drop and a vapor chamber begins to appear in the pressure regulator; if the coolant level in the pressure regulator drops to the target level, an initial vapor chamber at the preset pressure is established.

[0012] In one specific embodiment of this application, the above-mentioned control of the pressurizer to rise from a preset pressure to a target pressure, and control of the coolant in the pressurizer to continue heating from the saturation temperature corresponding to the preset pressure to the target temperature, in order to establish a target steam cavity at the target pressure, includes: continuing to operate an electric heater in the pressurizer to make the temperature of the coolant in the pressurizer continuously rise, and the pressure in the pressurizer continuously rise from the preset pressure; controlling the reduction of cooling of the primary coolant by the normal residual heat removal system, increasing the average temperature of the primary circuit through core decay heat, and ensuring that the temperature difference between the coolant temperature in the pressurizer and the coolant temperature in the hot section pipe of the primary circuit does not exceed the maximum temperature difference designed for the ripple tube in the primary circuit; if the pressurizer rises from the preset pressure to the target pressure, and the coolant in the pressurizer is heated to the target temperature, then a target steam cavity at the target pressure is established.

[0013] In one specific embodiment of this application, the preset pressure is 0.2 MPa.g, and the target pressure is 2.2 MPa.g.

[0014] In one specific embodiment of this application, the preset liquid level is 55% and the target liquid level is 50%.

[0015] In one specific embodiment of this application, the preset conditions also include a pressure inside the voltage regulator that is greater than or equal to -7 kPa.g and less than or equal to 2 kPa.g. Attached Figure Description

[0016] Figure 1 The diagram shows a process flow chart of a method for establishing a steam chamber in a pressurizer of a nuclear power unit.

[0017] Figure 2 This is a flowchart illustrating a method for establishing a steam cavity in a pressurizer of a nuclear power unit, as provided in an embodiment of this application.

[0018] Figure 3 As shown Figure 2 The illustrated embodiment shows a schematic diagram of the specific process for establishing a steam cavity in a pressurizer within a nuclear power unit.

[0019] Figure 4This is a flowchart illustrating a method for establishing a steam cavity in a pressurizer of a nuclear power unit, as provided in another embodiment of this application.

[0020] Figure 5 This is a flowchart illustrating a method for establishing a steam cavity in a pressurizer of a nuclear power unit, as provided in another embodiment of this application.

[0021] Figure 6 As shown Figure 5 The illustrated embodiment shows a schematic diagram of the specific process for establishing a steam cavity in a pressurizer within a nuclear power unit.

[0022] Figure 7 This is a flowchart illustrating a method for establishing a steam cavity in a pressurizer of a nuclear power unit, as provided in another embodiment of this application. Detailed Implementation

[0023] Figure 1 The diagram shows a flow chart illustrating a method for establishing a steam chamber in a pressurizer of a nuclear power unit. (Reference) Figure 1 The general process of establishing a steam chamber in the pressurizer of a nuclear power unit is as follows: The primary loop is filled until the coolant level in the pressurizer rises from 55% to full (i.e., 100%, taking approximately 3 hours). The primary loop continues to fill until the pressure in the pressurizer reaches 2.2 MPa.g, bringing the coolant to a liquid state (approximately 0.5 hours). The coolant in the pressurizer is then heated from its initial temperature (approximately 30°C) to 90°C (approximately 3 hours). The coolant in the pressurizer is further heated from 90°C to 110°C, while simultaneously adding deoxygenating chemicals (approximately 1 hour). After the coolant in the pressurizer is heated to 110°C, deoxygenation continues until it meets the required standards (approximately 2 hours). The coolant in the pressurizer is further heated from 110°C to 220°C (approximately 5.5 hours), and the coolant level in the pressurizer is reduced from full level to 50% (approximately 1.5 hours), thus establishing the target steam cavity. The total time required for the pressurizer to establish the target steam cavity is 3 hours + 0.5 hours + 3 hours + 1 hour + 2 hours + 5.5 hours + 1.5 hours = 16.5 hours. Therefore, the time required for the pressurizer to establish the steam cavity is as long as 16.5 hours, which undoubtedly reduces the start-up speed of the nuclear power unit and increases the operating cost of the nuclear power unit.

[0024] To address at least one of the aforementioned problems, embodiments of this application provide a method for establishing a steam chamber in a pressurizer of a nuclear power unit. The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0025] Figure 2 The diagram shown is a flowchart illustrating a method for establishing a steam chamber in a pressurizer of a nuclear power unit according to an embodiment of this application. Figure 3 As shown Figure 2 The illustrated embodiment provides a schematic flowchart of the method for establishing a steam cavity in a pressurizer within a nuclear power unit. This method is applicable to, but is not limited to, nuclear power units such as AP1000, Guohe One (CAP1000, CAP1400), and Hualong One (HPR1000) third-generation pressurized water reactors. Figure 2 As shown, the method includes steps S100 and S200.

[0026] S100: When the voltage regulator in the primary loop meets preset conditions, the coolant inside the voltage regulator is heated from its initial temperature to a preset temperature. Simultaneously with the heating of the coolant, deoxygenating chemicals are added to the voltage regulator to remove oxygen until it meets the required standards. The voltage regulator is then filled with water at a preset pressure until it reaches a liquid state. The preset conditions include: the coolant level in the voltage regulator is at a preset level; the preset level is greater than 50% and less than 90%; the preset temperature is greater than 100℃ and less than the upper temperature limit set for high-temperature corrosion of the voltage regulator body material; and the saturation temperature corresponding to the preset pressure is greater than the preset temperature.

[0027] For example, refer to Figure 3 The initial temperature is 30℃, the preset temperature is 110℃, the preset pressure is 0.2Mpa.g, and the preset liquid level is 55%. Figure 3 In the embodiment shown, step S100a is Figure 2 This is a specific implementation of step S100 in the illustrated embodiment. In step S100a, when the coolant level in the pressure regulator reaches 55%, the coolant in the pressure regulator can be heated from 30°C to 110°C (approximately 4.5 hours). Simultaneously with the start of heating of the coolant in the pressure regulator, a deoxygenating agent is added to the pressure regulator (approximately 1 hour), and the pressure regulator is filled with water at 0.2 MPa.g until it reaches a solid aqueous state (approximately 2.2 hours), until the pressure regulator is successfully deoxygenated (approximately 2 hours). Therefore, the entire process in step S100a, from heating the coolant in the pressure regulator from 30°C to 110°C, to successfully deoxygenating the pressure regulator, and to it reaching a solid aqueous state, takes 1 hour + 2.2 hours + 2 hours = 5.2 hours.

[0028] Combination Figure 1 The embodiment shown, Figure 1 In the illustrated embodiment, the entire process of heating the coolant in the voltage regulator from 30°C to 110°C, ensuring the voltage regulator is deoxygenated and in a liquid state, takes 3h + 0.5h + 3h + 1h + 2h = 9.5h. Therefore, it can be seen that using... Figure 3 The method of the illustrated embodiment is relative to Figure 1 The method of the illustrated embodiment can reduce the time by 4.3 hours.

[0029] It should be noted that the deoxygenating agent can be hydrazine or hydrogen peroxide, etc. If the deoxygenating agent is hydrazine, the preset temperature can be greater than 100℃ and less than 121℃. This avoids both a preset temperature that is too low, resulting in a slow heating rate, and a preset temperature that is too high, causing the hydrazine to decompose.

[0030] S200: Controls the preset pressure in the pressure regulator to rise to the target pressure, controls the coolant in the pressure regulator to heat to the target temperature, and controls the coolant level in the pressure regulator to drop to the target level, so as to establish the target vapor chamber.

[0031] For example, refer to Figure 3 The target pressure is 2.2 MPa.g, the target liquid level is 50%, and the target temperature is 220℃. Figure 3 In the embodiment shown, step S200a is Figure 2 One specific implementation of step S200 in the illustrated embodiment. In step S200a, the pressure in the pressure regulator is increased from 0.2 MPa.g to 2.2 MPa.g, the coolant in the pressure regulator is heated from 110°C to 220°C, and the coolant level in the pressure regulator is reduced from 100% to 50%, thereby establishing the target vapor chamber.

[0032] It should be noted that the preset liquid level can be a wide-range liquid level, while the target liquid level can be a narrow-range liquid level. The preset and target liquid levels can be set according to actual needs. For example, for Hualong One, CAP1000, or AP1000 nuclear power units, the preset liquid level can be selected as 55%, and the target liquid level can be selected as 50%. The target pressure can be set according to actual needs. For example, in some embodiments, the target pressure range is 2.1 MPa.g to 2.6 MPa.g. The target temperature can be set according to actual needs. For example, the target temperature can be the saturation temperature corresponding to the target pressure. Further, for example, if the target pressure range is 2.1 MPa.g to 2.6 MPa.g, then the target temperature range can be 214°C to 226°C.

[0033] According to the technical solution provided in this application, by simultaneously heating the coolant in the voltage regulator from its initial temperature to a preset temperature, adding deoxygenating chemicals to the voltage regulator to remove oxygen until it meets the deoxygenation requirements, and filling the voltage regulator with water at a preset pressure until it reaches a solid water state, the entire heating process of the coolant in the voltage regulator from its initial temperature to the preset temperature, the deoxygenation process of the voltage regulator, and the water filling process of the voltage regulator can be synchronized. Figure 1As illustrated in the embodiment, this application embodiment enables earlier initiation of deoxygenation in the pressurizer. Simultaneously, the dissolved oxygen concentration in the coolant within the pressurizer continuously decreases while the coolant temperature continuously rises. This temperature increase accelerates the deoxygenation process, thereby shortening the time required for pressurizer deoxygenation and coolant heating to the preset temperature. This benefits the nuclear power unit's start-up speed, reduces operating costs, and facilitates earlier power generation. Furthermore, by setting a preset temperature greater than 100°C but less than the upper temperature limit set for high-temperature corrosion of the pressurizer body material, this application embodiment effectively avoids the decomposition of deoxygenating chemicals due to excessively high preset temperatures, thus preventing increased deoxygenation time. Additionally, by setting a preset liquid level greater than 50% and less than 90%, this application embodiment avoids prolonged heating time due to excessively high preset liquid levels causing slow heating rates, and also avoids dry burning caused by exposed electric heaters due to excessively low preset liquid levels.

[0034] For nuclear power units that do not require vacuuming, such as the Hualong One reactor, the preset condition can be that the coolant level in the pressurizer is at a preset level. For nuclear power units that require vacuuming, in addition to the preset coolant level in the pressurizer, the preset condition can also include that the pressure in the pressurizer is in a slight vacuum state (i.e., the absolute pressure in the pressurizer is less than atmospheric pressure), for example, the pressure in the pressurizer is greater than or equal to -7 kPa·g and less than or equal to 2 kPa·g. This can prevent the coolant in the pressurizer from evaporating easily when heated due to excessively low absolute pressure, thus preventing the coolant in the pressurizer from boiling quickly when heated.

[0035] It should be noted that the pressure in the embodiments of this application is usually the relative pressure measured by the pressure gauge, where relative pressure = absolute pressure - atmospheric pressure.

[0036] Figure 4 The diagram shown is a flowchart illustrating a method for establishing a steam cavity in a pressurizer of a nuclear power unit, according to another embodiment of this application. Figure 4 As shown Figure 2 A variation of the illustrated embodiment. For example... Figure 4 As shown, with Figure 2 The difference in the illustrated embodiment is that steps S110 and S120 are... Figure 2 The illustrated embodiment shows a specific implementation of step S100, which involves heating the coolant in the voltage regulator from its initial temperature to a preset temperature.

[0037] S110: When the voltage regulator in the primary circuit meets the preset conditions, at least one electric heater is put into the voltage regulator to heat the coolant in the voltage regulator from the initial temperature to the preset temperature. The preset liquid level is greater than the liquid level that can just submerge at least one electric heater.

[0038] S120: If the coolant in the voltage regulator fails to be deoxygenated when heated to the preset temperature, the temperature of the coolant in the voltage regulator shall be controlled to not exceed the upper limit of the temperature set by the voltage regulator body material due to high temperature corrosion by adjusting the number of at least one electric heater.

[0039] According to the technical solution provided in this application, by introducing at least one electric heater into the pressurizer before the coolant level reaches full capacity, and using at least one electric heater to heat the coolant, the time required to establish the target steam cavity is reduced, thereby reducing the start-up time of the nuclear power unit. Furthermore, by setting a preset coolant level greater than 50% and less than 90%, and ensuring the preset level is high enough to just submerge at least one electric heater, the at least one electric heater can fully heat the coolant in the pressurizer, reducing or avoiding power loss and dry burning of the at least one electric heater. In addition, before the deoxygenation in the pressurizer is deemed satisfactory, the temperature of the coolant in the pressurizer is controlled to not exceed the upper temperature limit set for high-temperature corrosion of the pressurizer body material by adjusting the number of at least one electric heater, thereby preventing the decomposition of the deoxygenating chemicals and preventing corrosion of the pressurizer at high temperatures due to the adhering of decomposition products of the deoxygenating chemicals.

[0040] In at least one embodiment of this application, steps S130 to S170 are Figure 2 The embodiment shown illustrates a specific implementation method for step S100, in which oxygen-removing chemicals are added to the voltage regulator to remove oxygen until it meets the required standards.

[0041] S130: Add oxygen-removing chemicals into the voltage regulator.

[0042] It should be noted that the process of adding deoxygenating chemicals into the pressure regulator can be carried out simultaneously with the process of raising the coolant level and the coolant temperature in the pressure regulator, which helps to shorten the time required to establish the target steam cavity.

[0043] S140: Continuously monitor the dissolved oxygen concentration in the voltage regulator through a sampling system in the primary loop.

[0044] S150: The concentration of the deoxygenating agent in the voltage regulator is sampled using a sampling system.

[0045] S160: If the concentration of the deoxygenating agent in the voltage regulator is less than 1.5 times the dissolved oxygen concentration, then add the deoxygenating agent.

[0046] S170: If the dissolved oxygen concentration in the voltage regulator is less than 100 ppb, then the deoxygenation in the voltage regulator is deemed qualified.

[0047] In this embodiment, a primary sampling system continuously monitors the oxygen concentration of dissolved oxygen and the concentration of deoxygenating agents within the voltage regulator. Based on the ratio between the concentration of deoxygenating agents and the oxygen concentration of dissolved oxygen within the voltage regulator, it is determined whether to add deoxygenating agents, thereby improving the deoxygenation rate of the voltage regulator.

[0048] In at least one embodiment of this application, steps S180 and S190 are Figure 2 The embodiment shown is a specific implementation of step S100, in which the voltage regulator is filled with water to a water-solid state under a preset pressure.

[0049] S180: Controls the primary circuit to fill with water so that the coolant level in the voltage regulator rises from the preset level to the full level.

[0050] In some embodiments, a primary circuit is controlled to fill with water, and the primary circuit is controlled to stop draining, thereby raising the coolant level in the pressure regulator from a preset level to full level. In other embodiments, the flow rate of water filling the primary circuit is adjusted to be greater than the flow rate of water draining, thereby raising the coolant level in the pressure regulator from a preset level to full level.

[0051] S190: By adjusting the flow rate of the primary circuit for charging and discharging, the pressure inside the voltage regulator is increased to a preset pressure so that the coolant inside the voltage regulator is in a liquid state.

[0052] Specifically, when the coolant level in the pressure regulator rises to full level, the flow rate of the primary circuit for charging is adjusted to be greater than the flow rate for discharging, so that the number of water molecules per unit volume in the pressure regulator increases and becomes denser. This allows the pressure in the pressure regulator to be controlled to rise to the preset pressure, thereby keeping the coolant in the pressure regulator in a liquid state.

[0053] According to the technical solution provided in the embodiments of this application, by controlling the primary circuit to fill and drain water, the coolant in the voltage regulator is in a water-solid state, thereby achieving dynamic venting of the primary circuit by utilizing the water-solid state, thus improving the degassing effect.

[0054] Figure 5 The diagram shown is a flowchart illustrating a method for establishing a steam chamber in a pressurizer of a nuclear power unit, according to another embodiment of this application. Figure 6 As shown Figure 5 The illustrated embodiment shows a schematic diagram of the specific process for establishing a steam cavity in a pressurizer within a nuclear power unit. Figure 5 As shown Figure 2 A variation of the illustrated embodiment. For example... Figure 5 As shown, with Figure 2 The difference in the illustrated embodiment is that steps S210 and S220 are Figure 2 A specific implementation of step S200 in the illustrated embodiment.

[0055] S210: After the coolant in the regulator is heated from the preset temperature to the saturation temperature corresponding to the preset pressure, the coolant level in the regulator is reduced to the target level to establish the initial steam chamber at the preset pressure.

[0056] For example, refer to Figure 6 The preset temperature is 110℃, the preset pressure corresponds to a saturation temperature of 133℃, the target liquid level is 50%, and the preset pressure is 0.2Mpa.g. Figure 6 The step S210a shown is Figure 5 One specific implementation of step S210 in the illustrated embodiment. In step S210a, the coolant in the pressure regulator can be heated from 110°C to 133°C in a liquid state (approximately 0.5h), and then the coolant level in the pressure regulator can be lowered from full level to 50% (approximately 1.5h), thereby establishing an initial vapor chamber at 0.2 MPa.g.

[0057] It should be noted that the saturation temperature corresponding to the preset pressure only needs to be greater than the preset temperature and less than the target temperature. Therefore, this application does not specifically limit the magnitude of the saturation temperature corresponding to the preset pressure. For example, the range of the saturation temperature corresponding to the preset pressure can be 125℃ to 133℃. Specifically, when the preset pressure is 0.17 MPa.g, the saturation temperature corresponding to the preset pressure is 129℃; when the preset pressure is 0.2 MPa.g, the saturation temperature corresponding to the preset pressure is 133℃.

[0058] S220: Controls the pressure inside the regulator to rise from the preset pressure to the target pressure, and controls the coolant inside the regulator to continue heating from the saturation temperature corresponding to the preset pressure to the target temperature, so as to establish the target steam chamber at the target pressure.

[0059] For example, refer to Figure 6 The target pressure is 2.2 MPa.g, and the target temperature is 220℃. Figure 6 The step S220a shown is Figure 5 One specific implementation of step S220 in the illustrated embodiment. In step S220a, the pressure in the pressure regulator is increased from 0.2 MPa.g to 2.2 MPa.g, and the temperature of the coolant in the pressure regulator is further heated from 133°C to 220°C (approximately 2 hours), thereby establishing the target steam chamber at 2.2 MPa.g. Figure 6 In the illustrated embodiment, steps S210a and S220a take 0.5h + 1.5h + 2h = 4h.

[0060] Combination Figure 3 The embodiment shown, Figure 3In the embodiment shown, the process of step S200a takes 5.5h + 1.5h = 7h. Figure 6 Steps S210a and S220a shown are Figure 3 A variation of step S200a in the illustrated embodiment. Therefore, it can be seen that... Figure 6 The method of the illustrated embodiment is relative to Figure 3 The method in the illustrated embodiment can further reduce the time by 3 hours.

[0061] According to the technical solution provided in the embodiments of this application, by establishing an initial vapor chamber at a preset pressure lower than the target pressure, and then selectively heating the remaining coolant in the pressure regulator that has dropped to the target liquid level, this operation avoids heating the coolant at its full level in the pressure regulator, thereby improving heating efficiency and achieving the purpose of rapid temperature and pressure increase. For example, refer to... Figure 6 When the initial steam chamber is established, the coolant level in the pressure regulator is 50%, meaning the volume of coolant in the pressure regulator is only half of the total volume of the pressure regulator. Figure 3 The embodiment shown heats the coolant in the regulator to 220°C when the liquid level is full. The technical solution of this application embodiment can heat less coolant with the same power and number of electric heaters, which improves the cooling rate of the coolant, so that the coolant in the regulator can reach saturation faster, and it is also conducive to establishing the target steam cavity faster.

[0062] Figure 7 The diagram shown is a flowchart illustrating a method for establishing a steam chamber in a pressurizer of a nuclear power unit, according to another embodiment of this application. Figure 7 As shown Figure 5 A variation of the illustrated embodiment. For example... Figure 7 As shown, with Figure 5 The difference in the illustrated embodiment is that steps S211 and S212 are Figure 5 A specific implementation of step S210 in the illustrated embodiment.

[0063] S211: After the coolant in the regulator is heated from the preset temperature to the saturation temperature corresponding to the preset pressure, the primary circuit is stopped from filling with water and the primary circuit is controlled to drain, so that the coolant level in the regulator begins to drop and a vapor chamber begins to appear in the regulator.

[0064] Specifically, after the coolant in the pressure regulator is heated to the saturation temperature corresponding to the preset pressure, the primary circuit water filling is stopped, and the flow rate of the primary circuit discharge is increased, thereby accelerating the drop rate of the coolant level in the pressure regulator and reducing the time for the initial vapor chamber to form.

[0065] S212: If the coolant level in the regulator drops to the target level, an initial steam chamber is established at the preset pressure.

[0066] It should be noted that if the coolant level in the voltage regulator drops to the target level, the coolant level in the voltage regulator can be maintained at the target level by adjusting the flow rate of the primary circuit charging and discharging. For example, in some embodiments, the primary circuit charging and discharging can be stopped, thereby maintaining the coolant level in the voltage regulator at the target level.

[0067] According to the technical solution provided in the embodiments of this application, after the deoxygenation of the pressure regulator is qualified, the coolant in the pressure regulator is continued to be heated to the saturation temperature corresponding to the preset pressure, and the liquid level of the coolant in the pressure regulator is controlled to gradually decrease, so that a vapor chamber gradually appears in the pressure regulator, and the vapor chamber gradually becomes larger and larger as the liquid level decreases, until the liquid level of the coolant in the pressure regulator drops to the target liquid level, and the initial vapor chamber under the preset pressure is established.

[0068] In at least one embodiment of this application, steps S221 to S223 are Figure 5 A specific implementation of step S220 in the illustrated embodiment.

[0069] S221: Continue to supply electric heaters in the voltage regulator so that the temperature of the coolant in the voltage regulator continues to rise and the pressure in the voltage regulator continues to rise from the preset pressure.

[0070] It should be noted that the higher the temperature of the coolant inside the voltage regulator, the higher the pressure inside the voltage regulator will be.

[0071] S222: Control the cooling of the primary coolant by the normal residual heat removal system, increase the average temperature of the primary circuit through core decay heat, and ensure that the temperature difference between the coolant in the pressurizer and the coolant in the hot section pipe of the primary circuit does not exceed the maximum temperature difference designed for the ripple tube in the primary circuit.

[0072] It should be noted that when the primary loop needs to remove residual heat, the normal residual heat removal system is connected to the primary loop. The normal residual heat removal system is a collective term for all components that normally remove core decay heat. One end of the surge tube is connected to the pressurizer, and the other end is connected to the hot section piping. The average temperature of the primary loop is the average of the coolant temperatures in the hot section piping and the coolant temperatures in the cold section piping.

[0073] S223: If the pressure inside the regulator rises from the preset pressure to the target pressure, and the coolant inside the regulator is heated to the target temperature, then the target steam chamber at the target pressure is established.

[0074] In this embodiment, by adding more electric heaters within the pressurizer, the heating efficiency of the coolant within the pressurizer is accelerated, thus increasing the pressurization rate. By controlling and reducing the cooling of the primary loop by the normal residual heat removal system, the average temperature of the primary loop is increased through core decay heat. This ensures that the temperature difference between the coolant in the pressurizer and the coolant temperature in the hot section pipes of the primary loop does not exceed the maximum design temperature difference of the sloshing tubes in the primary loop, thereby avoiding impacting the sloshing tube lifespan.

[0075] It should be noted that the combination of the technical features in the embodiments of this application is not limited to the combination methods described in the embodiments of this application or the combination methods described in specific embodiments. All technical features described in this application can be freely combined or combined in any way, unless they contradict each other.

[0076] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications or equivalent substitutions made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for establishing a plenum in a pressurizer of a nuclear power plant, comprising: include: When the voltage regulator in the primary circuit meets preset conditions, the coolant in the voltage regulator is heated from the initial temperature to the preset temperature. At the same time as the coolant in the voltage regulator is heated, deoxygenating chemicals are added to the voltage regulator to remove oxygen until the deoxygenation is qualified. The voltage regulator is then filled with water to a water-solid state under a preset pressure. The preset conditions include the coolant level in the voltage regulator being a preset level, the preset level being greater than 50% and less than 90%, the preset temperature being greater than 100°C and less than the upper temperature limit set by the voltage regulator body material due to high-temperature corrosion, and the saturation temperature corresponding to the preset pressure being greater than the preset temperature. The preset pressure in the regulator is controlled to rise to the target pressure, the coolant in the regulator is controlled to heat to the target temperature, and the coolant level in the regulator is controlled to drop to the target level, so as to establish the target vapor chamber. The process of controlling the preset pressure in the pressure regulator to rise to the target pressure, controlling the coolant in the pressure regulator to heat to the target temperature, and controlling the coolant level in the pressure regulator to drop to the target level to establish the target vapor chamber includes: After the coolant in the regulator is heated from the preset temperature to the saturation temperature corresponding to the preset pressure, the liquid level of the coolant in the regulator is controlled to drop to the target liquid level in order to establish the initial vapor chamber under the preset pressure. The pressure in the regulator is controlled to rise from the preset pressure to the target pressure, and the coolant in the regulator is controlled to continue to be heated from the saturation temperature corresponding to the preset pressure to the target temperature, so as to establish the target steam cavity at the target pressure.

2. The method of claim 1, wherein, The process of controlling the heating of the coolant in the voltage regulator from an initial temperature to a preset temperature includes: At least one electric heater is placed inside the voltage regulator, and the coolant inside the voltage regulator is heated from an initial temperature to a preset temperature using the at least one electric heater. The preset liquid level is greater than the liquid level that can just submerge the at least one electric heater. If the coolant in the voltage regulator fails to be deoxygenated when heated to the preset temperature, the temperature of the coolant in the voltage regulator is controlled to not exceed the upper temperature limit set by the voltage regulator body material due to high-temperature corrosion by adjusting the number of at least one electric heater.

3. The method according to claim 1, characterized in that, The step of adding an oxygen-removing agent into the voltage regulator to remove oxygen until it meets the required level includes: Add oxygen-removing chemicals into the voltage regulator; The oxygen concentration of dissolved oxygen in the voltage regulator is continuously monitored through the sampling system of the first loop. The concentration of the deoxygenating agent in the voltage regulator is sampled using the sampling system. If the concentration of the deoxygenating agent in the voltage regulator is less than 1.5 times the oxygen concentration of the dissolved oxygen, then the deoxygenating agent is added. If the dissolved oxygen concentration in the voltage regulator is less than 100 ppb, then the deoxygenation in the voltage regulator is deemed qualified.

4. The method according to claim 1, characterized in that, The step of filling the voltage regulator with water to a liquid state under a preset pressure includes: The primary circuit is controlled to be filled with water so that the coolant level in the voltage regulator rises from the preset level to the full level. By adjusting the flow rate of the primary circuit for charging and discharging, the pressure inside the voltage regulator is controlled to rise to a preset pressure, so that the coolant inside the voltage regulator is in a liquid state.

5. The method according to claim 1, characterized in that, After heating the coolant in the pressure regulator from the preset temperature to the saturation temperature corresponding to the preset pressure, the coolant level in the pressure regulator is controlled to drop to the target level to establish an initial vapor chamber at the preset pressure, including: After the coolant in the pressure regulator is heated from the preset temperature to the saturation temperature corresponding to the preset pressure, the water filling of the first circuit is stopped and the first circuit is controlled to drain, so that the liquid level of the coolant in the pressure regulator begins to drop and a steam chamber begins to appear in the pressure regulator. If the coolant level in the regulator drops to the target level, an initial steam chamber is established at the preset pressure.

6. The method according to claim 1, characterized in that, The method of controlling the pressure regulator to rise from the preset pressure to the target pressure, and controlling the coolant in the pressure regulator to continue heating from the saturation temperature corresponding to the preset pressure to the target temperature, in order to establish the target vapor chamber at the target pressure, includes: An electric heater is continuously introduced into the voltage regulator to cause the temperature of the coolant in the voltage regulator to rise continuously, and the pressure in the voltage regulator to rise continuously from the preset pressure. Control the cooling of the primary coolant by the normal residual heat removal system, increase the average temperature of the primary circuit through core decay heat, and ensure that the temperature difference between the coolant in the pressurizer and the coolant in the hot section pipe of the primary circuit does not exceed the maximum temperature difference designed for the ripple tube in the primary circuit. If the pressure inside the regulator rises from the preset pressure to the target pressure, and the coolant inside the regulator is heated to the target temperature, then a target steam chamber is established at the target pressure.

7. The method according to any one of claims 1 to 6, characterized in that, The preset pressure is 0.2 MPa.g, and the target pressure is 2.2 MPa.g.

8. The method according to any one of claims 1 to 6, characterized in that, The preset liquid level is 55%, and the target liquid level is 50%.

9. The method according to any one of claims 1 to 6, characterized in that, The preset conditions also include that the pressure inside the voltage regulator is greater than or equal to -7 kPa.g and less than or equal to 2 kPa.g.

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