A method for removing hydrogen from a primary circuit of a pressurized water reactor nuclear power plant

Abstract

The application provides a method for removing hydrogen in a pressurized water reactor nuclear power plant primary loop, which comprises the following steps: removing hydrogen through control of a pressurizer exhaust hydrogen removal process and simultaneous control of a hydrogen dissolution process in the primary loop coolant, so that the hydrogen dissolution in the primary loop after the pressurizer exhaust cavity is less than 5 cc / kg, and the primary loop is in an atmospheric condition. The hydrogen removal method determines the completion judgment standard of the pressurizer exhaust and the prerequisite condition of the pressurizer exhaust cavity, and simultaneously determines the matching hydrogen dissolution control strategy in the primary loop coolant during shutdown, so that the hydrogen dissolution in the primary loop system after the pressurizer exhaust cavity is less than 5 cc / kg, the main line work period of the large repair shutdown is shortened, the low-temperature crack propagation of the primary loop system caused by the hydrogen dissolution is avoided, and the economic benefits are maximized.

Description

Technical Field

[0001] This invention belongs to the technical field of hydrogen removal in the primary loop, and particularly relates to a method for hydrogen removal in the primary loop of a pressurized water reactor nuclear power plant. Background Technology

[0002] Under the intense radiation of a nuclear reactor, the coolant in the primary loop decomposes, producing strong oxidizing substances. These substances corrode nuclear equipment, reducing its reliability. Therefore, during reactor operation, hydrogen is typically added to the coolant to suppress irradiation decomposition. Hydrogen accumulates in the primary coolant, pressurizer gas phase, and their connecting pipelines. However, before shutting down the reactor for maintenance and venting the primary loop to the atmosphere, hydrogen must be removed from the primary loop to prevent an explosion of the hydrogen-oxygen mixture. This ensures that the dissolved hydrogen in the primary coolant after the pressurizer extinguishing chamber is less than 5 cc / kg.

[0003] The AP1000 third-generation nuclear power unit adopts a passive and simplified system design concept, which simplifies the related systems and equipment for hydrogen removal in the primary coolant circuit during shutdown compared to the second-generation nuclear power unit. However, this unique system design and operating mode have created significant challenges and difficulties in managing the hydrogen removal schedule in the primary coolant circuit during shutdown and controlling the dissolved hydrogen concentration in the pressurizer venting chamber. Based on AP1000 operating experience, after entering hot standby mode during shutdown, the shortest main line duration for hydrogen removal in a nuclear power unit of the same reactor type is 28.2 hours, impacting the unit's economics. Furthermore, due to the lack of quantifiable and executable prerequisites for pressurizer venting chamber operation, several instances of a sharp increase in dissolved hydrogen concentration in the primary coolant circuit after pressurizer venting chamber operation have occurred, increasing the risk of low-temperature crack propagation in the primary coolant system materials. Summary of the Invention

[0004] The purpose of this invention is to provide a method for hydrogen removal in the primary loop of a pressurized water reactor nuclear power plant. This method significantly shortens the main construction period for hydrogen removal in the primary loop during major and minor overhaul shutdowns, improves the economic efficiency of the power plant, and ensures that the dissolved hydrogen in the primary loop coolant after the pressurizer extinguishing chamber is less than 5 cc / kg, thus avoiding the risk of low-temperature crack propagation and degradation of system materials due to excessively high dissolved hydrogen concentration in the primary loop coolant.

[0005] To achieve this objective, the present invention adopts the following technical solution:

[0006] This invention provides a method for hydrogen removal in the primary loop of a pressurized water reactor nuclear power plant. The method includes controlling the hydrogen removal process of the pressurizer exhaust and simultaneously controlling the hydrogen dissolution process in the primary loop coolant, so that the hydrogen dissolution in the primary loop after the pressurizer exhaust chamber is less than 5cc / kg.

[0007] In this invention, the hydrogen removal method determines the criteria for completing pressurizer exhaust and the prerequisites for pressurizer extinguishing chamber, and simultaneously determines the corresponding hydrogen dissolution control strategy in the primary coolant during reactor shutdown. This ensures that the dissolved hydrogen in the primary coolant system after the pressurizer extinguishing chamber is less than 5 cc / kg, thus shortening the main shutdown period for major and minor overhauls.

[0008] As a preferred technical solution of the present invention, the hydrogen removal process of the voltage regulator exhaust includes the following steps:

[0009] (1) When the reactor is shut down for ≥7 days, establish the venting conditions for the pressurizer;

[0010] (2) When the reactor is in hot standby mode 7 days before shutdown, remove the hydrogen from the upper gas phase of the pressurizer and column A of the automatic depressurization system.

[0011] (3) After the reactor is shut down and enters hot standby mode, continue to remove hydrogen from the lower gas phase of the pressurizer and column B of the automatic depressurization system until the liquid level of the pressurizer is raised to the water body.

[0012] In this invention, during power operation, because the temperature of the regulator spray water is about 60°C lower than the regulator temperature, the temperature of the regulator spray water increases after it is injected into the regulator, reducing the solubility of hydrogen. Hydrogen in the spray water then precipitates and enters the regulator's gas phase. Due to heat dissipation from the Automatic Depressurization System (ADS) pipelines and the condensation effect of the top spray water on the regulator, hydrogen accumulates in the ADS-A and ADS-B pipelines and in the regulator's gas phase. This is because the regulator's exhaust valve is located at the end of the pressure boundary of the ADS-A pipeline, and the ADS pipeline is located at the top of the regulator. Therefore, performing pressurizer venting before reactor shutdown, such as in power operation mode (mode 1), start-up mode (mode 2), and hot standby mode (mode 3), can effectively remove hydrogen accumulated in the ADS-A column and the upper part of the pressurizer, and shorten the main line operation period for hydrogen removal during reactor shutdown. However, since the ADS-B column is not connected to the ADS-A column, the hydrogen accumulated in the ADS-B column needs to be depressurized in the primary loop system and returned to the upper part of the pressurizer before it can be removed by pressurizer venting.

[0013] As a preferred technical solution of the present invention, the conditions for establishing the exhaust of the voltage regulator include:

[0014] (1) Use nitrogen to purge the waste liquid treatment system until the oxygen concentration in the waste gas treatment system is less than 1.8%;

[0015] (2) Reduce the pressure of the coolant condensate tank interlock shut-off regulator exhaust channel of the waste liquid treatment system to ≤30KPa;

[0016] (3) Adjust the liquid level of the coolant condensate tank of the waste liquid treatment system to 0.5-0.7m, and then establish an exhaust channel.

[0017] In this invention, the pressure in step (2) is reduced to ≤30KPa, for example, it can be 20KPa, 21KPa, 22KPa, 23KPa, 24KPa, 25KPa, 26KPa, 27KPa, 28KPa, 29KPa or 30KPa, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0018] In this invention, the liquid level of the coolant condensate tank in step (3) is adjusted to 0.5-0.7m, for example, it can be 0.5m, 0.52m, 0.54m, 0.56m, 0.58m, 0.6m, 0.62m, 0.64m, 0.68m or 0.7m, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0019] As a preferred technical solution of the present invention, the method for removing hydrogen from the upper gas phase of the pressurizer and column A of the automatic depressurization system includes the following steps: performing pressurizer exhaust and hydrogen removal once every 15-20 minutes until the coolant condensate tank of the waste liquid treatment system is interlocked to close the pressurizer exhaust channel for more than 60 seconds, and the pressurizer exhaust and hydrogen removal is completed before the reactor shutdown.

[0020] In this invention, the time for the coolant condensate tank to interlock and close the pressure regulator exhaust channel is greater than 60s, for example, it can be 60s, 61s, 62s, 100s, 120s, 150s or 300s, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0021] In this invention, before the reactor is shut down, the amount of hydrogen in the upper part of the pressurizer and column A of the automatic depressurization system is 70-80% of the total hydrogen volume.

[0022] As a preferred embodiment of the present invention, the method for discharging hydrogen from the lower gas phase of the pressurizer and column B of the automatic depressurization system until the liquid level of the pressurizer is raised to the water phase includes the following steps:

[0023] (1) Adjust the pressure of the coolant condensate tank interlock shut-off regulator exhaust channel of the waste liquid treatment system to ≤41KPa;

[0024] (2) Perform pressure regulator venting and hydrogen removal every 15-20 minutes, while raising the pressure regulator level to 90%-95% until the coolant condensate tank of the waste liquid treatment system is interlocked to close the pressure regulator venting channel for more than 60 seconds. After completing the primary circuit hydrogen removal, and after meeting the prerequisite conditions of the pressure regulator extinguishing chamber, continue to raise the pressure regulator level to the water body. During the pressure regulator extinguishing chamber process, continue to perform pressure regulator venting every 15-20 minutes until the pressure regulator level is ≥95%.

[0025] In this invention, during the venting process of the pressure regulator in step (2), the liquid level of the pressure regulator is simultaneously raised to 90%-95%, for example, it can be 90%, 91%, 92%, 93%, 94% or 95%, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0026] In this invention, the time for the coolant condensate tank of the waste liquid treatment system in step (2) to interlock and close the pressure regulator exhaust channel is greater than 60s, for example, it can be 60s, 61s, 62s, 120s, 150s or 300s, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0027] In this invention, during the process of the pressure regulator extinguishing chamber in step (2), the pressure regulator is vented to a level ≥95%, which can be, for example, 95%, 96%, 97%, 98%, 99% or 100%, but is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0028] In this invention, after the primary loop system is cooled and depressurized, the voltage regulator exhausts and removes hydrogen. The hydrogen in the ADS-B column returns to the upper part of the gas phase of the voltage regulator, and the amount of hydrogen accumulated in the ADS-B column is 20-30% of the total hydrogen.

[0029] As a preferred technical solution of the present invention, the prerequisites for the gas extinguishing chamber of the pressure regulator include: the main pump speed is 50-88%, the spray temperature of the pressure regulator is ≤75℃, the proportional heater and the standby heater of the pressure regulator are all in operation, the liquid level of the pressure regulator is ≥90%, the temperature difference between the gas and liquid phases of the pressure regulator is ≤10℃, and the pressure of the primary circuit is 2.2-2.7MPa.

[0030] In this invention, the main pump speed is 50-88%, for example, it can be 50%, 55%, 60%, 65%, 70%, 75%, 80% or 88%, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0031] In this invention, the spray temperature of the voltage regulator is ≤75℃, for example, it can be 65℃, 66℃, 67℃, 68℃, 69℃, 70℃, 71℃, 72℃, 73℃, 74℃ or 75℃, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0032] In this invention, the voltage regulator liquid level is ≥90%, for example, it can be 90%, 91%, 92%, 93%, 94% or 95%, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0033] In this invention, the temperature difference between the gas and liquid phases of the voltage regulator is ≤10℃, for example, it can be 2℃, 3℃, 4℃, 5℃, 6℃, 7℃, 8℃, 9℃ or 10℃, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0034] In this invention, the pressure of the primary circuit is 2.2-2.7 MPa, for example, it can be 2.2 MPa, 2.25 MPa, 2.3 MPa, 2.35 MPa, 2.4 MPa, 2.45 MPa, 2.5 MPa, 2.55 MPa, 2.6 MPa, 2.65 MPa or 2.7 MPa, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0035] As a preferred technical solution of the present invention, the method for controlling dissolved hydrogen in the primary coolant includes the following steps:

[0036] (1) When the reactor is shut down for ≥7 days, the dissolved hydrogen concentration in the primary loop should be controlled at 26-30 cc / kg. When the dissolved hydrogen concentration in the primary loop is less than 26 cc / kg, the concentration should be adjusted to 0.086-0.3 m³ / kg. 3 The hydrogen addition at a flow rate of / h controls the concentration of dissolved hydrogen in the primary loop at 26-30cc / kg;

[0037] (2) When switching to hot standby mode 7 days before reactor shutdown, control the dissolved hydrogen concentration in the primary loop to 16-25 cc / kg. When the dissolved hydrogen concentration in the primary loop is less than 16 cc / kg, adjust the concentration at 0.086-0.3 m³ / kg. 3 The hydrogen addition at a flow rate of / h controls the concentration of dissolved hydrogen in the primary loop at 26-30cc / kg;

[0038] (3) When the reactor is shut down and enters hot standby mode, the primary loop hydrogenation is terminated, and the primary loop dissolved hydrogen is reduced by primary loop boronizing and pressurizer spraying.

[0039] In this invention, the concentration of dissolved hydrogen in the control loop described in step (1) is 26-30 cc / kg, for example, it can be 26 cc / kg, 26.5 cc / kg, 27 cc / kg, 27.5 cc / kg, 28 cc / kg, 28.5 cc / kg, 29 cc / kg, 29.5 cc / kg or 30 cc / kg, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0040] In this invention, the concentration of dissolved hydrogen in the control loop described in step (2) is 16-25 cc / kg, for example, it can be 16 cc / kg, 17 cc / kg, 18 cc / kg, 19 cc / kg, 20 cc / kg, 21 cc / kg, 22 cc / kg, 23 cc / kg, 24 cc / kg or 25 cc / kg, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0041] In this invention, step (3) requires maintaining a reducing environment in the primary circuit to prevent corrosion products from being released in particulate form and forming hot spots.

[0042] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] The hydrogen removal method for the primary loop of a pressurized water reactor nuclear power plant provided by this invention accurately controls the hydrogen removal process from the pressurizer chamber of the reactor, while simultaneously controlling the dissolved hydrogen content in the primary loop coolant. This shortens the main shutdown period for major and minor overhauls, avoids a sharp increase in dissolved hydrogen in the primary loop after the pressurizer chamber is shut down, and prevents low-temperature crack propagation in the primary loop system materials caused by high concentrations of dissolved hydrogen. This improves equipment reliability and maximizes economic benefits. The method was validated during the overhaul shutdown of HY102 in Haiyang and the planned shutdown of HY2 during the 2022 Spring Festival. Both tests achieved the goal of not disrupting the main shutdown process, and the dissolved hydrogen concentration in the primary loop after the pressurizer chamber was shut down was less than 5 cc / kg, demonstrating significant potential for wider application. Detailed Implementation

[0045] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0046] Example 1

[0047] This embodiment provides a method for hydrogen removal in the primary loop of a pressurized water reactor nuclear power plant. The method includes: controlling the hydrogen removal process by controlling the pressurizer exhaust and simultaneously controlling the hydrogen dissolution process in the primary coolant.

[0048] The hydrogen removal process from the pressure regulator exhaust includes the following steps:

[0049] (1) When the reactor is shut down for ≥7 days, establish the exhaust conditions for the pressurizer;

[0050] 1.1 Purge the waste liquid treatment system with nitrogen until the oxygen concentration in the waste gas treatment system is 1.5%;

[0051] 1.2 Reduce the pressure in the exhaust channel of the coolant condensate tank interlock shut-off regulator of the waste liquid treatment system to 30 kPa;

[0052] 1.3 Adjust the coolant condensate tank level of the waste liquid treatment system to 0.6m, and then establish an exhaust channel;

[0053] (2) When the reactor is shut down 7 days before the start of mode 3, remove the hydrogen from the upper gas phase of the pressurizer and column A of the automatic depressurization system.

[0054] 2.1 Perform pressurizer venting and hydrogen removal every 15 minutes until the coolant condensate tank of the continuous waste liquid treatment system is interlocked to close the pressurizer venting channel for 65 seconds. Pressurizer venting and hydrogen removal are completed before reactor shutdown.

[0055] (3) After the reactor is shut down and enters mode 3, continue to purge the hydrogen from the lower gas phase of the pressurizer and column B of the automatic depressurization system until the liquid level of the pressurizer is raised to the water body.

[0056] 3.1 Close the interlock of the coolant drain tank in the waste liquid treatment system and adjust the pressure of the pressure regulator exhaust channel to 41 kPa;

[0057] 3.2 Every 15 minutes, the pressure regulator is vented and dehydrogenated, while the pressure regulator level is increased to 90% until the coolant condensate tank of the waste liquid treatment system is interlocked and the pressure regulator venting channel is closed for 65 seconds. After the primary loop dehydrogenation is completed and the prerequisites for the pressure regulator extinguishing chamber are met, the pressure regulator level is increased to a solid water level. During the pressure regulator extinguishing chamber process, the pressure regulator is vented every 15 minutes until the pressure regulator level is 100%. The prerequisites for the pressure regulator extinguishing chamber are: main pump speed of 50%, pressure regulator spray temperature of 75℃, pressure regulator proportional heater and standby heater in operation, pressure regulator level of 90%, pressure regulator gas-liquid two-phase temperature difference of 5℃, and primary loop pressure of 2.4MPa.

[0058] 3.3 After the pressure regulator level is raised to the solid water level, the dissolved hydrogen in the primary circuit is less than 5cc / kg.

[0059] The process of dissolving hydrogen in the primary coolant includes the following steps:

[0060] (1) When the reactor is shut down for ≥7 days, hydrogen removal is carried out by SG primary side diffusion to secondary side, pressurizer spraying and boron dilution, and the concentration of dissolved hydrogen in the primary loop is controlled to be 28cc / kg.

[0061] (2) When the reactor is shut down 7 days before the start of the shutdown, hydrogen removal is carried out through SG primary side diffusion to secondary side, pressurizer spraying and boron dilution, and the concentration of dissolved hydrogen in the primary loop is controlled to be 20cc / kg.

[0062] (3) When the reactor is shut down and enters mode 3, the hydrogenation of the primary loop is terminated, and hydrogen is removed by boronizing of the primary loop and spraying of the pressurizer, while ensuring the reducing environment of the primary loop.

[0063] Applying the hydrogen removal method for the primary loop of a pressurized water reactor nuclear power plant provided in this embodiment, during the HY102 overhaul and the planned shutdown of Unit 2 during the 2022 Spring Festival, the hydrogen concentration of the primary coolant after the pressurizer's gas extinguishing chamber was less than 5cc / kg, and the main hydrogen removal process took 0 hours, thus avoiding the risk of material crack propagation in the primary loop system.

[0064] Example 2

[0065] The only difference between this embodiment and embodiment 1 is that, except for 1.2, the pressure of the exhaust channel of the coolant condensate tank interlock shut-off regulator of the waste liquid treatment system is reduced to 28 kPa; the rest is the same as embodiment 1.

[0066] The hydrogen removal method for the primary loop of a pressurized water reactor nuclear power plant provided in this embodiment has a main hydrogen removal cycle of 0 hours.

[0067] Example 3

[0068] The only difference between this embodiment and embodiment 1 is that, except that the process of removing hydrogen from the upper part of the pressurizer gas phase and column A of the automatic depressurization system is not performed in step (2) of the pressurizer exhaust and hydrogen removal process when the reactor is shut down 7 days before mode 3; and the prerequisite in step (3) of the pressurizer extinguishing chamber is not executed, the rest are the same as in embodiment 1.

[0069] The hydrogen removal method for the primary loop of a pressurized water reactor nuclear power plant provided in this embodiment has a main hydrogen removal time of 28.2 hours, and the dissolved hydrogen in the primary loop coolant after the pressurizer extinguishing chamber rises to more than 50cc / kg.

[0070] The applicant declares that the detailed structural features of the present invention are illustrated through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions for the components selected in the present invention, additions of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0071] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0072] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0073] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for removing hydrogen from a primary circuit of a pressurized water nuclear power plant, characterized in that, The hydrogen removal method comprises: removing hydrogen from the pressurizer exhaust cavity and simultaneously controlling the hydrogen dissolution in the primary coolant, so that the hydrogen dissolution in the pressurizer exhaust cavity after the pressurizer is less than 5 cc / kg; The pressurizer exhaust hydrogen removal process comprises the following steps: (1) When the reactor is stopped for more than 7 days, the exhaust condition of the pressurizer is established; (2) When the reactor is stopped for 7 days to the hot standby mode, the hydrogen in the gas phase upper part of the pressurizer and the automatic depressurization system A column is removed; (3) After the reactor is stopped and enters the hot standby mode, the hydrogen in the gas phase lower part of the pressurizer and the automatic depressurization system B column is continuously removed until the liquid level of the pressurizer is raised to the water entity.

2. The method of claim 1, wherein, The establishment of the exhaust condition of the pressurizer comprises: (1) The waste liquid treatment system is purged with nitrogen until the oxygen concentration of the waste gas treatment system is less than 1.8%; (2) The coolant drain tank of the waste liquid treatment system is interlocked to close the exhaust flow channel of the pressurizer, and the pressure of the exhaust flow channel of the pressurizer is adjusted to be less than or equal to 30 KPa; (3) The liquid level of the coolant drain tank of the waste liquid treatment system is adjusted to 0.5-0.7 m, and then the exhaust flow channel is established.

3. The method of claim 1, wherein, The method for removing the hydrogen in the gas phase upper part of the pressurizer and the automatic depressurization system A column comprises the following steps: performing pressurizer exhaust hydrogen removal every 15-20 min until the time for which the coolant drain tank of the waste liquid treatment system is interlocked to close the exhaust flow channel of the pressurizer is greater than 60 s, and the pressurizer exhaust hydrogen removal before the reactor is stopped is completed.

4. The method of claim 1, wherein, The method for removing the hydrogen in the gas phase lower part of the pressurizer and the automatic depressurization system B column until the liquid level of the pressurizer is raised to the water entity comprises the following steps: (1) The pressure of the coolant drain tank of the waste liquid treatment system is adjusted to be less than or equal to 41 KPa, and the exhaust flow channel of the pressurizer is interlocked to be closed; (2) The pressurizer exhaust hydrogen removal is performed every 15-20 min while the liquid level of the pressurizer is raised to 90%-95%, until the time for which the coolant drain tank of the waste liquid treatment system is interlocked to close the exhaust flow channel of the pressurizer is greater than 60 s, and the primary loop hydrogen removal is completed, and at the same time, the prerequisite conditions of the pressurizer exhaust cavity are met, then the liquid level of the pressurizer is continuously raised to the water entity, and the pressurizer exhaust is performed every 15-20 min during the pressurizer exhaust cavity process until the liquid level of the pressurizer is greater than or equal to 95%.

5. The method of claim 4, wherein, The prerequisite conditions of the pressurizer exhaust cavity comprise: the main pump rotating speed is 50-88%, the spray temperature of the pressurizer is less than or equal to 75 ℃, all of the proportional heater and the backup heater of the pressurizer are put into operation, the liquid level of the pressurizer is greater than or equal to 90%, the temperature difference between the gas and liquid phases of the pressurizer is less than or equal to 10 ℃, and the pressure of the primary loop is 2.2-2.7 MPa.

6. The method of claim 1, wherein, The method for controlling the hydrogen dissolution in the primary coolant comprises the following steps: (1) When shutdown ≥ 7 days, the concentration of dissolved hydrogen in the primary loop is controlled to be 26-30 cc / kg, and when the dissolved hydrogen in the primary loop is less than 26 cc / kg, hydrogen is added at a flow rate of 0.086-0.3 m 3 / h to control the concentration of dissolved hydrogen in the primary loop to be 26-30 cc / kg; (2) When the concentration of dissolved hydrogen in the primary circuit is less than 16 cc / kg, hydrogen is added at a flow rate of 0.086-0.3 m 3 / h to control the concentration of dissolved hydrogen in the primary circuit to 26-30 cc / kg when the primary circuit is in the hot standby mode 7 days before shutdown. (3) When the reactor is stopped and enters the hot standby mode, the hydrogen addition in the primary loop is terminated, and the hydrogen dissolution in the primary loop is reduced through the primary loop boronization and the pressurizer spray.