Method for exiting overhauling key path of nuclear power unit pressure stabilizer

Abstract

The application relates to a method for exiting a key path of a nuclear power unit stabilizer overhaul, which comprises the following steps: all heaters in the stabilizer are put into operation to ensure that the stabilizer is maintained in a saturated state; the RRA system is put into operation, so that the primary loop is cooled at a preset cooling rate; the injection amount of the main pump shaft seal is maintained, the charging flow of the primary loop is adjusted to be within a first preset flow range, and the bleeding flow is adjusted to be within a second preset flow range, so that the water level in the stabilizer rises; the spray valve in the stabilizer is adjusted, so that the pressure of the primary loop is maintained at a preset pressure; when the water level of the stabilizer reaches a first preset water level, the bleeding control valve is switched to control the pressure of the primary loop; before the water level of the stabilizer reaches a second preset water level, the opening degree of the spray valve in the stabilizer is adjusted according to the bleeding flow change, until the opening degree of the bleeding control valve is unchanged, and the steam cavity is completely eliminated. The steam cavity elimination process of the stabilizer does not occupy the key path time of the overhaul, so that the key path time of the overhaul is shortened, and the overhaul period is ensured.

Description

Technical Field

[0001] This application relates to the field of nuclear power plant pressurizer technology, and in particular to a method for exiting the critical path of a nuclear power unit pressurizer during overhaul. Background Technology

[0002] Nuclear reactors share a single pressurizer and a corresponding depressurization tank in their primary loop. The pressure of the reactor coolant system is maintained stable by automatic regulation using the pressurizer's electric heating elements and sprayers.

[0003] Currently, during nuclear power plant overhauls, a steam extinguishing operation must be performed before the reactor primary loop cools to 130 degrees Celsius. This process involves extinguishing the steam in the pressurizer, followed by rapid cooling of the primary loop. This not only occupies the critical path of the overhaul but also causes significant transient changes in pressure and temperature within the reactor coolant system (RCP system) during the extinguishing process. These transient changes can lead to operational events exceeding operational limits, hydrogen rebound, and ultimately, delays in the overhaul schedule. Summary of the Invention

[0004] Based on this, this application provides a method for removing the pressurizer from the critical path of a nuclear power unit overhaul. The pressurizer steam chamber is extinguished during the cooling process of the primary loop, so that the process of extinguishing the pressurizer steam chamber does not occupy the critical path time of the overhaul, thereby shortening the critical path time of the overhaul and ensuring the overhaul schedule.

[0005] This application provides a method for exiting the critical path of overhaul for a nuclear power unit's pressurizer, including the following steps:

[0006] S10. Activate all heaters in the voltage regulator to ensure that the voltage regulator maintains a saturated state.

[0007] S20. Put the waste heat removal system into operation, so that the primary circuit cools down at a preset cooling rate.

[0008] S40. Maintain the injection volume of the main pump shaft seal, adjust the charging flow of the primary circuit to the first preset flow range, and adjust the discharge flow to the second preset flow range to raise the water level in the pressure stabilizer.

[0009] S60. Adjust the spray valve in the voltage regulator to maintain the primary circuit pressure at the preset pressure;

[0010] S70. When the pressure regulator water level reaches the first preset water level, switch the discharge control valve to control the primary circuit pressure.

[0011] S90. Before the pressure stabilizer water level reaches the second preset water level, if the second preset water level is higher than the first preset water level, adjust the opening of the spray valve in the pressure stabilizer according to the change in the discharge flow rate until the opening of the discharge control valve remains unchanged and the steam chamber is completely extinguished.

[0012] In some embodiments, after step S90, the method further includes the following steps:

[0013] S100. Disconnect the heaters one by one from the voltage regulator, and at the same time adjust the spray valve in the voltage regulator to be fully open.

[0014] In some embodiments, in step S100, adjusting the spray valve in the voltage regulator to full opening specifically includes:

[0015] Adjust the spray valve inside the voltage regulator to the first preset opening degree, continue for the first preset time, and then adjust the spray valve inside the voltage regulator to fully open.

[0016] In some embodiments, step S20 specifically includes the following steps:

[0017] S21. Open the inlet valve of the waste heat discharge system to preheat the waste heat discharge system.

[0018] S22. Adjust the charging flow and discharging flow of the first circuit so that the voltage regulator water level reaches the third preset water level, which is lower than the first preset water level.

[0019] S23. Open the outlet valve of the waste heat discharge system and adjust the regulating valve of the waste heat discharge system so that the primary circuit cools down at a preset cooling rate.

[0020] In some embodiments, in step S90, adjusting the opening of the spray valve in the voltage regulator according to the change in the outflow specifically includes:

[0021] When the increase in the outflow exceeds the upper limit margin, increase the opening of the spray valve in the voltage regulator;

[0022] When the decrease in the outflow exceeds the lower limit margin, reduce the opening of the spray valve in the voltage regulator.

[0023] In some embodiments, after step S70, the method further includes the following steps:

[0024] Maintain the charging flow rate unchanged, and open the low-pressure discharge circuit regulating valve to full opening.

[0025] In some embodiments, prior to step S40, the method further includes the following steps:

[0026] S30. Blow air into the steam chamber of the voltage regulator.

[0027] In some embodiments, after step S40, the method further includes the following steps:

[0028] S50: Control the REA system to replenish water to the capacity control box, and at the same time, blow air into the capacity control box.

[0029] In some embodiments, the first preset opening degree is 50% to 60%, and the first preset time is more than 1 hour.

[0030] In some embodiments, the first preset flow rate range is 20t / h to 25t / h, the second preset flow rate range is 10t / h to 15t / h, the preset pressure is 25bar, the preset cooling rate is 28℃ / h, the first preset water level is 1.8m, the second preset water level is 2.2m, and the third preset water level is -1m to 1m.

[0031] According to the method for exiting the critical path of a nuclear power unit pressurizer during overhaul provided in this application, during the cooling process of the primary loop, by activating all heaters in the pressurizer and adjusting the charging and discharging flow rates, the steam chamber in the pressurizer is gradually extinguished, and the pressurizer is always kept in a saturated state. By combining the discharging flow valve and the manually adjusted spray valve, the pressure control during the steam chamber extinguishing process is optimized, ensuring the pressure stability of the primary loop and achieving rapid steam chamber extinguishing. The pressurizer steam chamber extinguishing process no longer occupies the critical path time of the overhaul, thereby shortening the critical path time of the overhaul and ensuring the overhaul schedule.

[0032] In addition, the voltage regulator extinguishing chamber is completed during the primary loop cooling process, which enables uninterrupted cooling of the primary loop, greatly reducing the probability of a breach in the waste heat removal system, and the source term continues to improve.

[0033] Furthermore, the pressurizer remains saturated throughout the entire extinguishing process, and the heaters are gradually removed after the extinguishing process, which reduces the probability of condensation and depressurization in the primary loop and ensures nuclear safety. It also prevents hydrogen from being stored in the pressurizer's borosilicate water. At the same time, the pressurizer chamber and the control box are purged during the entire extinguishing process, which allows the released hydrogen to be discharged in a timely manner, thereby greatly reducing the probability of hydrogen rebound. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the connection structure of the RCP system, RCV system, REA system and RRA system in the primary loop of a nuclear power plant in some embodiments of this application;

[0035] Figure 2 A flowchart illustrating a method for exiting the critical path of overhaul for a nuclear power unit pressurizer, provided in some embodiments of this application. Detailed Implementation

[0036] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0037] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0038] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0039] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0040] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0041] It should be noted that when an element is referred to as being "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is considered to be "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0042] Please see Figure 1 This document illustrates a schematic diagram of the connection structure of the RCP system, RCV system, REA system, and RRA system in the primary loop of a nuclear power plant according to some embodiments of this application. The RCP system is the reactor coolant system, the RCV system is the chemical and vessel control system, the REA system is the reactor boron and water supply system, and the RRA system is the residual heat removal system.

[0043] The RCP system includes a reactor pressure vessel, a pressurizer, a main pump, and a steam generator connected in sequence by a main pipeline. There are multiple main pumps and multiple steam generators, with one main pump and one steam generator corresponding to each other.

[0044] The RCV system includes a capacity control box RCV02BA, an RCV pump (charge pump), a charge control valve RCV046VP, a discharge control valve RCV013VP, and a low-pressure discharge circuit regulating valve RCV310VP. The charge control valve RCV046VP can be used to manually adjust the charge flow of the primary circuit, while the discharge control valve RCV013VP and the low-pressure discharge circuit regulating valve RCV310VP can be used to adjust the discharge flow of the primary circuit. Among them, the discharge control valve RCV013VP can automatically adjust its opening according to the pressure of the primary circuit, and can respond to the pressure changes of the primary circuit in a timely manner without manual control.

[0045] The REA system can replenish water into the capacity control box RCV02BA.

[0046] The RRA system includes an inlet valve, an RRA pump, a regulating valve, a heat exchanger, and an outlet valve. The regulating valve can adjust the flow rate of heat exchange with the heat exchanger, thereby adjusting the cooling rate of the primary loop of the RRA system.

[0047] Please see Figure 2 The flowchart illustrates a method for exiting the critical path of overhaul for a nuclear power unit pressurizer according to an embodiment of this application, which includes the following steps:

[0048] S10. Activate all heaters in the voltage regulator to ensure that the voltage regulator maintains a saturated state.

[0049] Specifically, the pressurizer contains six heaters: RCP001RS, RCP002RS, RCP003RS, RCP004RS, RCP005RS, and RCP006RS. By activating all six heaters, the pressurizer is kept in a saturated state during the extinguishing process, avoiding the risk of condensation and depressurization in the primary loop and ensuring nuclear safety. At the same time, the pressurizer remains in a saturated state throughout the extinguishing process, preventing hydrogen from accumulating in the borosilicate water within the pressurizer.

[0050] S20. Put the RRA system into operation so that the primary loop cools down at a preset cooling rate.

[0051] In some embodiments, step S20 above includes the following steps:

[0052] S21. Open the inlet valve of the waste heat discharge system to preheat the waste heat discharge system.

[0053] The inlet valve is opened, and the hot water from the primary circuit is used to preheat the waste heat discharge system to protect the equipment.

[0054] S22. Adjust the charging flow and discharging flow of the primary circuit to make the pressure regulator water level reach the third preset water level;

[0055] Specifically, the charging flow rate of the primary circuit can be adjusted by regulating the opening of the charging control valve RCV046VP, and the discharge flow rate of the primary circuit can be adjusted by regulating the opening of the discharge control valve RCV013VP. The third preset water level can be -1m to 1m, preferably 0m. By utilizing the preheating process of the waste heat discharge system to raise the water level of the pressure regulator to the third preset water level, the time for raising the water level of the pressure regulator can be saved, thereby shortening the time for the pressure regulator to extinguish the steam in the steam chamber, and thus shortening the critical path time for overhaul.

[0056] S23. Open the outlet valve of the waste heat discharge system and adjust the regulating valve of the waste heat discharge system so that the primary circuit cools down at a preset cooling rate.

[0057] By opening the outlet valve of the waste heat discharge system, the waste heat discharge system is fully connected to the primary loop, thereby putting the waste heat discharge system into operation. The regulating valve of the waste heat discharge system is adjusted to regulate the flow rate of heat exchange with the heat exchanger in the waste heat discharge system, so that after the waste heat discharge system is put into operation, the primary loop cools down at a preset cooling rate.

[0058] In some embodiments, the preset cooling rate is preferably 28°C / h.

[0059] S40. Maintain the main pump shaft seal injection volume, adjust the charging flow rate of the primary circuit to the first preset flow rate range, and adjust the discharge flow rate to the second preset flow rate range to raise the water level in the pressure stabilizer.

[0060] Specifically, the charging flow rate of the primary circuit can be adjusted by the charging control valve RCV046VP, and the draining flow rate of the primary circuit can be adjusted by the draining control valve RCV013VP.

[0061] In some embodiments, the first preset flow rate range is 20t / h to 25t / h, and the second preset flow rate range is 10t / h to 15t / h. Calculations show that at a platform of 170℃, with all heaters in the pressure regulator operational, the maximum injection rate of the pressure regulator can reach 21.6t / h, while the pressure regulator remains saturated. The injection rate of the main pump shaft seal is generally 6t / h. Therefore, if the charging flow rate is set to 25t / h and the discharge flow rate to 10t / h, after satisfying the cooling contraction of the primary circuit, the injection rate of the pressure regulator will be approximately 10t / h. While the water level in the pressure regulator rises, it will still remain saturated.

[0062] Therefore, by adjusting the charging flow rate of the primary loop to the first preset flow rate range and adjusting the discharge flow rate to the second preset flow rate range, the water level in the pressurizer can be raised, gradually extinguishing the steam chamber. At the same time, the pressurizer remains saturated, thus ensuring that the pressurizer remains saturated during the steam chamber extinguishing process, avoiding the risk of condensation and depressurization in the primary loop, and ensuring nuclear safety.

[0063] S60. Adjust the spray valve inside the voltage regulator to maintain the primary circuit pressure at the preset pressure, thus ensuring the stability of the primary circuit pressure.

[0064] Specifically, the spray valve inside the voltage regulator can be manually adjusted to maintain the primary circuit pressure at a preset pressure.

[0065] In some embodiments, the preset pressure is preferably 25 bar to meet the pressure required for the main pump to operate.

[0066] S70. When the pressure regulator water level reaches the first preset water level, switch the discharge control valve RCV013VP to control the primary circuit pressure.

[0067] The RCV013VP drain control valve can automatically adjust its opening size according to the pressure of the primary circuit, responding promptly to pressure changes in the primary circuit without manual control, thus facilitating pressure control of the primary circuit.

[0068] In some embodiments, the first preset water level is preferably 1.8m.

[0069] S90. Before the pressure stabilizer water level reaches the second preset water level, adjust the opening of the spray valve in the pressure stabilizer according to the change of the discharge flow rate until the opening of the discharge control valve RCV013VP remains unchanged, that is, the primary circuit pressure remains unchanged and the steam chamber is completely extinguished.

[0070] In some embodiments, the second preset water level is preferably 2.2m.

[0071] In some embodiments, in step S90 above, adjusting the opening of the spray valve in the voltage regulator according to the change in the outflow specifically includes:

[0072] When the increase in the outflow exceeds the upper limit margin, increase the opening of the spray valve in the voltage regulator;

[0073] When the decrease in the outflow exceeds the lower limit margin, reduce the opening of the spray valve in the voltage regulator.

[0074] It should be noted that when the change in the discharge flow rate is between the upper and lower margin limits, the primary loop pressure remains basically stable. When the increase in the discharge flow rate exceeds the upper margin limit, the primary loop pressure rises, the opening of the spray valve in the pressure regulator is increased, the primary loop pressure drops, and the lower discharge control valve automatically decreases. When the decrease in the discharge flow rate exceeds the lower margin limit, the primary loop pressure drops, the opening of the spray valve in the pressure regulator is decreased, the primary loop pressure rises, and the lower discharge control valve automatically increases. This process is repeated several times until adjusting the spray valve opening results in no response from the lower discharge control valve RCV013VP, meaning the primary loop pressure remains unchanged and the steam chamber is completely extinguished. This ensures that the primary loop pressure remains stable during the steam chamber extinguishing process of the pressure regulator.

[0075] In some embodiments of this application, after step S90 above, the method for removing the nuclear power unit's pressurizer from the critical overhaul path further includes the following steps:

[0076] S100, disconnect the heaters in the voltage regulator one by one, and at the same time slowly adjust the spray valves in the voltage regulator to fully open.

[0077] By disengaging the heaters one by one after the pressurizer's steam extinguishing chamber, the probability of condensation and pressure loss in the primary loop can be reduced, ensuring nuclear safety. Additionally, it ensures that the temperature drop rate within the pressurizer does not exceed the specified requirement of 112℃ / h before the pressurizer is completely disengaged, preventing the temperature difference between the primary loop and the pressurizer from exceeding 110℃.

[0078] In some embodiments, the step of slowly adjusting the spray valve in the voltage regulator to full opening in step S100 above specifically includes:

[0079] Adjust the spray valve inside the voltage regulator to the first preset opening degree, continue for the first preset time, and then adjust the spray valve inside the voltage regulator to fully open.

[0080] In some embodiments, the first preset opening degree is preferably 50% to 60%, and the first preset time is preferably more than 1 hour.

[0081] In some embodiments of this application, after step S70 above, the method for removing the nuclear power unit's pressurizer from the critical overhaul path further includes the following steps:

[0082] S80. Maintain the charging flow rate unchanged and slowly open the low-pressure discharge circuit regulating valve RCV310VP to full opening to ensure that RCV013VP can respond to the pressure changes of the primary circuit in a timely and accurate manner.

[0083] In some embodiments of this application, prior to step S40 above, the method for removing the nuclear power unit's pressurizer from the critical overhaul path further includes the following steps:

[0084] S30. Blow air into the steam chamber of the voltage regulator.

[0085] Specifically, air can be blown into its steam chamber through the purging line of the voltage regulator.

[0086] It should be noted that the execution order of step S30 is not limited to being executed after step S10 or S20. Step S10 or S20 and step S103 can be executed simultaneously, or step S30 can be executed first and then step S10 or S20. This ensures that the pressurizer's purge line is always in operation throughout the entire steam extinguishing process, so that the evolved hydrogen can be discharged in a timely manner, reducing the probability of hydrogen rebound.

[0087] In some embodiments of this application, after step S40 above, the method for removing the nuclear power unit's pressurizer from the critical overhaul path further includes the following steps:

[0088] S50: Control the REA system to replenish water to the capacity control box, and at the same time, blow air into the capacity control box.

[0089] Specifically, the REA system can be set to manual water replenishment mode to avoid the limitation of automatic replenishment start / stop exceeding 6 times / hour. The capacity control tank can be purged via the purge line to ensure timely removal of precipitated hydrogen, further reducing the probability of hydrogen rebound.

[0090] The aforementioned method for removing the pressurizer from the critical path of a nuclear power unit during overhaul involves activating all heaters within the pressurizer during the primary loop cooling process. This is achieved by adjusting the charging and discharging flow rates to gradually extinguish the steam chamber within the pressurizer while maintaining a saturated state. By combining the discharging flow valve with manual adjustment of the spray valve, pressure control during the steam chamber extinguishing process is optimized, ensuring pressure stability in the primary loop and achieving rapid steam chamber extinguishing. The pressurizer steam chamber extinguishing process does not occupy the critical path time of the overhaul, thus shortening the critical path time and ensuring the overhaul schedule. Furthermore, completing the pressurizer steam chamber extinguishing during the primary loop cooling process ensures uninterrupted cooling of the primary loop, significantly reducing the probability of a breach in the residual heat removal system and continuously improving the source term. Furthermore, the pressurizer remains saturated throughout the entire extinguishing process, and the heaters are gradually removed after the extinguishing process, which reduces the probability of condensation and depressurization in the primary loop and ensures nuclear safety. It also prevents hydrogen from being stored in the pressurizer's borosilicate water. At the same time, the pressurizer chamber and the control box are purged during the entire extinguishing process, which allows the released hydrogen to be discharged in a timely manner, thereby greatly reducing the probability of hydrogen rebound.

[0091] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0092] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A method for removing a nuclear power unit's pressurizer from the critical overhaul path, characterized in that, Includes the following steps: S10. Activate all heaters in the voltage regulator to ensure that the voltage regulator maintains a saturated state. S20. Put the waste heat removal system into operation, so that the primary circuit cools down at a preset cooling rate. S40. Maintain the main pump shaft seal injection volume, adjust the charging flow rate of the primary circuit to the first preset flow rate range, and adjust the discharge flow rate to the second preset flow rate range to raise the water level in the pressure stabilizer. S60. Adjust the spray valve in the voltage regulator to maintain the primary circuit pressure at the preset pressure; S70. When the pressure regulator water level reaches the first preset water level, switch the discharge control valve to control the primary circuit pressure. S90. Before the pressure stabilizer water level reaches the second preset water level, if the second preset water level is higher than the first preset water level, adjust the opening of the spray valve in the pressure stabilizer according to the change in the discharge flow rate until the opening of the discharge control valve remains unchanged and the steam chamber is completely extinguished.

2. The method for exiting the critical overhaul path of a nuclear power unit's pressurizer according to claim 1, characterized in that, Following step S90, the following steps are also included: S100. Disconnect the heaters one by one from the voltage regulator, and at the same time adjust the spray valve in the voltage regulator to be fully open.

3. The method for exiting the critical overhaul path of a nuclear power unit's pressurizer according to claim 2, characterized in that, In step S100, adjusting the spray valve inside the voltage regulator to full open specifically includes: Adjust the spray valve inside the voltage regulator to the first preset opening degree, continue for the first preset time, and then adjust the spray valve inside the voltage regulator to fully open.

4. The method for exiting the critical overhaul path of a nuclear power unit's pressurizer according to claim 1, characterized in that, Step S20 specifically includes the following steps: S21. Open the inlet valve of the waste heat discharge system to preheat the waste heat discharge system. S22. Adjust the charging flow and discharging flow of the first circuit so that the water level of the voltage regulator reaches the third preset water level, which is lower than the first preset water level. S23. Open the outlet valve of the waste heat discharge system and adjust the regulating valve of the waste heat discharge system so that the primary circuit cools down at a preset cooling rate.

5. The method for exiting the critical overhaul path of a nuclear power unit's pressurizer according to claim 1, characterized in that, In step S90, adjusting the opening of the spray valve in the voltage regulator according to the change in the outflow specifically includes: When the increase in the outflow exceeds the upper limit margin, increase the opening of the spray valve in the voltage regulator; When the decrease in the outflow exceeds the lower limit margin, reduce the opening of the spray valve in the voltage regulator.

6. The method for exiting the critical overhaul path of a nuclear power unit's pressurizer according to claim 1, characterized in that, Following step S70, the method further includes the following steps: S80. Maintain the charging flow rate unchanged and open the low-pressure discharge circuit regulating valve to full opening.

7. The method for exiting the critical overhaul path of a nuclear power unit's pressurizer according to claim 1, characterized in that, Prior to step S40, the method further includes the following steps: S30. Blow air into the steam chamber of the voltage regulator.

8. The method for exiting the critical overhaul path of a nuclear power unit's pressurizer according to claim 1, characterized in that, Following step S40, the method further includes the following steps: S50: Control the REA system to replenish water to the capacity control box, and at the same time, blow air into the capacity control box.

9. The method for exiting the critical overhaul path of a nuclear power unit's pressurizer according to claim 3, characterized in that, The first preset opening degree is 50% to 60%, and the first preset time is more than 1 hour.

10. The method for exiting the critical overhaul path of a nuclear power unit's pressurizer according to claim 4, characterized in that, The first preset flow rate range is 20t / h to 25t / h, the second preset flow rate range is 10t / h to 15t / h, the preset pressure is 25bar, the preset cooling rate is 28℃ / h, the first preset water level is 1.8m, the second preset water level is 2.2m, and the third preset water level is -1m to 1m.

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