Nuclear power plant stator cooling water system and maintenance method of nuclear power plant generator stator bar

Abstract

The invention discloses a nuclear power plant stator cooling water system and a nuclear power plant generator stator bar maintenance method. The nuclear power plant stator cooling water system comprises a generator stator bar, a stator cooling water tank, an input pipeline, a backflow pipeline, a branch pipeline, a first action pipeline, a second action pipeline, a compressed air source and a nitrogen source. According to the maintenance method, different maintenance modes are formulated according to different maintenance states of the generator stator bar, and the maintenance of the stator bar is realized to the greatest extent under the condition that the maintenance progress is not influenced. The maintenance method is divided into three stages, the first stage is compressed air maintenance and stator bar internal humidity control, the second stage is nitrogen maintenance, and the third stage is dosing wet maintenance, so that the whole shutdown maintenance process of the generator stator bar can be covered by the combined maintenance mode of compressed air, nitrogen and wet maintenance; and a control standard is formulated for each maintenance mode so as to ensure the maintenance effect, and corrosion of the equipment is slowed down to the greatest extent.

Description

Technical Field

[0001] The present invention relates to the technical field of nuclear power plant chemistry, and particularly to a stator cooling water system for a nuclear power plant and a maintenance method for a stator bar of a generator in a nuclear power plant. Background Art

[0002] The stator bar of a generator in a nuclear power plant is a copper wire. During the operation of the unit, in order to prevent the corrosion of the copper wire and the influence of corrosion products on the safe operation of the stator cooling water system, a stator cooling water environment with low conductivity and slightly alkaline is generally adopted. However, after the unit is shut down, due to the residual water in the stator cooling water system and carbon dioxide in the air entering the pipeline of the stator cooling water system, the corrosion of the hollow copper wire in the stator cooling water system is aggravated. In order to prevent the corrosion perforation of the stator bar and the blockage of the stator bar by corrosion products, affecting the safe operation of the stator cooling water system, the stator bar needs to be maintained after the unit is shut down. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a stator cooling water system for a nuclear power plant and a maintenance method for a stator bar of a generator in a nuclear power plant, so as to solve the problem that after the unit is shut down, due to the residual water in the stator cooling water system and carbon dioxide in the air entering the pipeline of the stator cooling water system, the corrosion of the hollow copper wire in the stator cooling water system is aggravated, affecting the performance of the stator bar of the generator.

[0004] The technical solution adopted by the present invention to solve its technical problem is to construct a stator cooling water system for a nuclear power plant, which includes a stator bar of a generator, a stator cooling water tank, an input pipeline, a return pipeline, a branch pipeline, a first function pipeline, a second function pipeline, a compressed air source and a nitrogen source;

[0005] Two ends of the input pipeline are respectively connected to the output end of the stator cooling water tank and the inlet end of the stator bar of the generator, two ends of the return pipeline are connected to the input end of the stator cooling water tank and the inlet end of the stator bar of the generator, and two ends of the branch pipeline are respectively connected to the interface end of the input pipeline and the access end of the return pipeline;

[0006] The first function pipeline is connected to the first function end of the stator bar of the generator, and the second function pipeline is connected to the second function end of the stator bar of the generator;

[0007] The compressed air source is used to provide compressed air for the stator bar of the generator, the nitrogen source is used to provide nitrogen for the stator bar of the generator, the compressed air source can be connected to the first function pipeline or the second function pipeline, and the nitrogen source can be connected to the first function pipeline.

[0008] In some embodiments, the nuclear power plant stator cooling water system further includes a demineralized water device and an alkali addition tank, both of which are connected to the stator cooling water tank;

[0009] A demineralized water control valve is provided between the demineralized water device and the stator cooling water tank;

[0010] An alkali addition control valve is provided between the alkali addition tank and the stator cooling water tank.

[0011] In some embodiments, the nuclear power plant stator cooling water system further includes a discharge pipeline connected to the discharge end of the stator cooling water tank, and a discharge control valve is provided on the discharge pipeline.

[0012] In some embodiments, a first function control valve is provided on the first function pipeline;

[0013] A second function control valve is provided on the second function pipeline;

[0014] On the input pipeline, a first input control valve, a stator cooling water pump, a second input control valve, and a third input control valve are sequentially provided along the fluid input direction;

[0015] On the return pipeline, a first return control valve and a second return control valve are sequentially provided along the fluid input direction;

[0016] A branch control valve is provided on the branch pipeline.

[0017] In this embodiment, a maintenance method for the stator bars of the generator in a nuclear power plant is also constructed, which is used to maintain the stator bars of the generator when the nuclear power plant stator cooling water system is overhauled. Based on the nuclear power plant stator cooling water system described above, it includes the following steps:

[0018] S1. Drain the stator cooling water in the nuclear power plant stator cooling water system;

[0019] S2. Blow the stator bars of the generator with compressed air;

[0020] S3. Carry out nitrogen maintenance on the stator bars of the generator;

[0021] S4. Carry out wet maintenance by adding medicine to the stator bars of the generator.

[0022] In some embodiments, in step S1, when the nuclear power plant stator cooling water system needs to be overhauled, stop the stator cooling water pump, and open the first input control valve, the second input control valve, the third input control valve, the discharge control valve, the first return control valve, the second return control valve, the second function control valve, and the first function control valve.

[0023] In some embodiments, step S2 includes:

[0024] S21. Close the first input control valve, the second input control valve, the third input control valve, the first return control valve, the second return control valve, and the discharge control valve;

[0025] S22. Connect to the compressed air source using the first action pipeline;

[0026] S23. Open the second action control valve and the first action control valve, measure the humidity of the discharged compressed air at the interface of the second action pipeline until the humidity of the compressed air at the interface of the second action pipeline is less than the preset humidity value, and then keep the compressed air continuously purged and maintained for a certain period of time;

[0027] S24. After keeping the compressed air continuously purged and maintained for a certain period of time, connect to the compressed air source using the second action pipeline, measure the humidity of the discharged compressed air at the interface of the first action pipeline until the humidity of the compressed air at the interface of the first action pipeline is less than the preset humidity value, and then keep the compressed air continuously purged and maintained for the preset time;

[0028] S25. After the compressed air purging is completed, close the first action control valve and the second action control valve, and disassemble the compressed air source.

[0029] In some embodiments, step S3 includes:

[0030] S31. Close the first return control valve and the third input control valve, connect to the nitrogen source using the first action pipeline, open the first action control valve and the second action control valve, inject nitrogen into the generator stator bar, and measure the nitrogen concentration at the interface of the second action pipeline;

[0031] S32. Close the second action control valve, keep the first action control valve open, and fill the nitrogen inside the generator stator bar to the preset pressure value;

[0032] S33. Close the first action control valve and open the second action control valve for exhaust;

[0033] S34. Repeat step S32 and step S33 until the nitrogen concentration measured at the interface of the second action pipeline is greater than the preset nitrogen concentration value;

[0034] S35. When the nitrogen concentration measured at the interface of the second action pipeline is greater than the preset nitrogen concentration value, close the first action control valve and the second action control valve, and maintain the nitrogen pressure in the generator stator bar, the first action pipeline, and the second action pipeline at the preset pressure value;

[0035] Wherein, when the nitrogen pressure in the generator stator bar, the first action pipeline, and the second action pipeline is less than the predetermined pressure value, open the first action control valve to supplement the nitrogen pressure to the preset pressure value;

[0036] S36. When nitrogen maintenance needs to be stopped, close the first acting control valve and the second acting control valve, and disassemble the nitrogen source.

[0037] In some embodiments, in step S3, when the nitrogen maintenance is interrupted, step S2 is executed.

[0038] In some embodiments, in step S4, cooling water is injected into the stator cooling water tank, and a chemical dosing pump is started to add sodium hydroxide to the cooling water, so that the conductivity of the cooling water after adding sodium hydroxide is greater than a preset conductivity value, and the pH value of the cooling water after adding sodium hydroxide is greater than a preset pH value, until the stator cooling water system of the nuclear power plant completely resumes normal operation.

[0039] Implementing the present invention has the following beneficial effects: The maintenance method for the stator bars of the generator in this nuclear power plant formulates different maintenance methods according to different maintenance states of the stator bars of the generator, and maximally realizes the maintenance of the stator bars without affecting the progress of maintenance. The maintenance method is divided into three stages. The first stage is compressed air maintenance to control the humidity inside the stator bars. The second stage is nitrogen maintenance. The third stage is chemical dosing wet maintenance. Implementing the combined maintenance method of compressed air + nitrogen + wet maintenance can cover the entire outage maintenance process of the stator bars of the generator, and control standards are formulated for each maintenance method to ensure the maintenance effect, and the corrosion of the equipment is slowed down to the greatest extent. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] In order to more clearly illustrate the technical solutions of the present invention, the present invention will be further described below in conjunction with the drawings and embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts. In the drawings:

[0041] Figure 1 is the overall structural schematic diagram of the stator cooling water system of the nuclear power plant in some embodiments of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0042] In order to have a clearer understanding of the technical features, objectives, and effects of the present invention, the specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings. In the following description, it should be understood that the orientation or positional relationships indicated by "front", "rear", "upper", "lower", "left", "right", "longitudinal", "transverse", "vertical", "horizontal", "top", "bottom", "inner", "outer", "head", "tail", etc. are based on the orientation or positional relationships shown in the drawings, and are constructed and operated in a specific orientation, solely for the convenience of describing the present technical solution, rather than indicating that the indicated device or element must have a specific orientation. Therefore, it should not be construed as a limitation to the present invention.

[0043] It should also be noted that, unless otherwise clearly specified and limited, terms such as "installation", "connection", "linkage", "fixation", "setting" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements or the interaction relationship between two elements. When an element is referred to as being "above" or "below" another element, the element can be "directly" or "indirectly" located above the other element, or there may also be one or more intermediate elements provided. Terms such as "first", "second", "third", etc. are only for the convenience of describing the present technical solution, and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first", "second", "third", etc. can explicitly or implicitly include one or more of such features. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0044] Please refer to Figure 1 , which is a stator cooling water system of a nuclear power plant in some embodiments of the present invention. It includes a generator stator bar 1, a stator cooling water tank 2, an input pipeline 3, a return pipeline 4, a branch pipeline 5, a first function pipeline 6, a second function pipeline 7, a compressed air source, and a nitrogen source. The two ends of the input pipeline 3 are respectively connected to the output end of the stator cooling water tank 2 and the inlet end of the generator stator bar 1. The two ends of the return pipeline 4 are connected to the input end of the stator cooling water tank 2 and the inlet end of the generator stator bar 1. The two ends of the branch pipeline 5 are respectively connected to the interface end of the input pipeline 3 and the access end of the return pipeline 4. The first function pipeline 6 is connected to the first function end of the generator stator bar 1. The second function pipeline 7 is connected to the second function end of the generator stator bar 1. The compressed air source is used to provide compressed air for the generator stator bar 1, and the nitrogen source is used to provide nitrogen for the generator stator bar 1. The compressed air source can be connected to the first function pipeline 6 or the second function pipeline 7, and the nitrogen source can be connected to the first function pipeline 6.

[0045] Specifically, the stator cooling water system of a nuclear power plant is a system used to cool the stator windings of the generator and the high-voltage bushings on the outgoing side. It belongs to a closed-loop system. Its main function is to remove the heat generated by the stator windings of the generator during operation through cooling water to ensure the normal operation of the generator. The settings of the input pipeline 3, the return pipeline 4, the first function pipeline 6, the second function pipeline 7, the compressed air source, and the nitrogen source enable different maintenance methods to be formulated according to the on-site maintenance situation during the overhaul of the stator cooling water system of the nuclear power plant. A combined maintenance method of compressed air + nitrogen + wet maintenance can be achieved, which can cover the entire outage overhaul process of the generator stator bars 1 and slow down the corrosion of the equipment to the greatest extent. The setting of the branch pipeline 5 allows the cooling water in the input pipeline 3 to directly return to the stator cooling water tank 2 without passing through the generator stator bars 1. The first function pipeline 6 and the second function pipeline 7 are separately located on both sides of the generator stator bars 1.

[0046] The stator cooling water system of a nuclear power plant also includes a demineralized water device 8 and an alkali addition tank 9. Both the demineralized water device 8 and the alkali addition tank 9 are connected to the stator cooling water tank 2. A demineralized water control valve 81 is provided between the demineralized water device 8 and the stator cooling water tank 2, and an alkali addition control valve 91 is provided between the alkali addition tank 9 and the stator cooling water tank 2. The demineralized water device 8 can provide demineralized water or condensate as the stator cooling water source to the stator cooling water tank 2 as needed. The stator cooling water enters the generator stator bars 1 through the input pipeline 3 and then returns to the stator cooling water tank 2 through the return pipeline 4. The demineralized water device 8 only provides demineralized water or cooling water through the demineralized water control valve 81 when the liquid level of the stator cooling water tank 2 drops or the stator cooling water is changed and discharged. The alkali addition tank 9 can add sodium hydroxide to the cooling water to adjust the pH value of the cooling water.

[0047] In addition, the stator cooling water system of a nuclear power plant also includes a discharge pipeline 10 connected to the discharge end of the stator cooling water tank 2. A discharge control valve 101 is provided on the discharge pipeline 10. A first function control valve 61 is provided on the first function pipeline 6, and a second function control valve 71 is provided on the second function pipeline 7. Along the fluid input direction on the input pipeline 3, a first input control valve 31, a stator cooling water pump 32, a second input control valve 33, and a third input control valve 34 are successively provided. Along the fluid input direction on the return pipeline 4, a first return control valve 41 and a second return control valve 42 are successively provided. A branch control valve 51 is provided on the branch pipeline 5. During the normal operation of the stator cooling water system of the nuclear power plant, the first input control valve 31, the second input control valve 33, the third input control valve 34, the first return control valve 41, and the second return control valve 42 are in the open state, and the first function control valve 61, the second function control valve 71, the branch control valve 51, the demineralized water control valve 81, and the alkali addition control valve 91 are in the closed state.

[0048] In this embodiment, a maintenance method for the stator bars of a nuclear power plant generator is also constructed, which is used to maintain the stator bars 1 of the generator when the nuclear power plant's demineralized water system is overhauled. Based on the above nuclear power plant demineralized water system, it includes the following steps:

[0049] S1. Drain the demineralized water in the nuclear power plant demineralized water system;

[0050] S2. Blow the stator bars 1 of the generator with compressed air;

[0051] S3. Carry out nitrogen maintenance on the stator bars 1 of the generator;

[0052] S4. Carry out wet maintenance by adding medicine to the stator bars 1 of the generator.

[0053] Among them, in step S1, when the nuclear power plant demineralized water system needs to be overhauled, stop the demineralized water pump 32, open the first input control valve 31, the second input control valve 33, the third input control valve 34, the discharge control valve 101, the first return control valve 41, the second return control valve 42, the second function control valve 71, and the first function control valve 61, and open the above control valves to drain the demineralized water in the nuclear power plant demineralized water system.

[0054] Step S2 includes:

[0055] S21. Close the first input control valve 31, the second input control valve 33, the third input control valve 34, the first return control valve 41, the second return control valve 42, and the discharge control valve 101;

[0056] S22. Connect to the compressed air source using the first function pipeline 6;

[0057] S23. Open the second function control valve 71 and the first function control valve 61, measure the humidity of the discharged compressed air at the interface of the second function pipeline 7, and keep the compressed air continuously blown and maintained for a certain period of time until the humidity of the compressed air at the interface of the second function pipeline 7 is less than the preset humidity value;

[0058] S24. After maintaining the continuous blowing and maintenance of the compressed air for a certain period of time, connect to the compressed air source using the second function pipeline 7, measure the humidity of the discharged compressed air at the interface of the first function pipeline 6, and keep the compressed air continuously blown and maintained for the preset time until the humidity of the compressed air at the interface of the first function pipeline 6 is less than the preset humidity value.

[0059] S25. After the compressed air blowing is completed, close the first function control valve 61 and the second function control valve 71, and disassemble the compressed air source.

[0060] Among them, the preset humidity value is 30%. Understandably, when using a compressed air source to blow and purge the generator stator bar 1, first measure the humidity of the discharged compressed air at the interface of the second action pipeline 7 until the humidity of the compressed air at the interface of the second action pipeline 7 is less than 30%. Otherwise, it is necessary to promptly adjust the compressed air flow rate to reduce its humidity to below 30%, and then maintain continuous compressed air blowing and maintenance. The humidity of the compressed air at the interface of the action pipeline can be measured daily until the generator stator bar 1 can be maintained with nitrogen. According to the on-site maintenance situation, after meeting the nitrogen maintenance conditions, switch to nitrogen maintenance; if not, pass compressed air.

[0061] In order to ensure that all the residual water inside the generator stator bar 1 is completely blown and purged, after maintaining continuous compressed air blowing and maintenance at the first action pipeline 6 for a certain period of time, then switch the second action pipeline 7 to access the compressed air source to maintain continuous compressed air blowing and maintenance. Measure the humidity of the discharged compressed air at the interface of the first action pipeline 6 until the humidity of the compressed air at the interface of the first action pipeline 6 is less than 30%. Otherwise, it is necessary to promptly adjust the compressed air flow rate to reduce its humidity to below 30%. After the humidity of the compressed air at the interface of the first action pipeline 6 is less than 30%, maintain continuous compressed air blowing and maintenance for a preset time. That is, both sides of the generator stator bar 1 are blown with compressed air to ensure that the moisture inside the generator stator bar 1 is dried.

[0062] Step S3 includes:

[0063] S31. Close the first reflux control valve 41 and the third input control valve 34, connect the nitrogen source using the first action pipeline 6, open the first action control valve 61 and the second action control valve 71, and inject nitrogen into the generator stator bar 1, and measure the nitrogen concentration at the interface of the second action pipeline 7;

[0064] S32. Close the second action control valve 71, and keep the first action control valve 61 open to fill the nitrogen inside the generator stator bar 1 to the preset pressure value;

[0065] S33. Close the first action control valve 61 and open the second action control valve 71 for exhaust;

[0066] S34. Repeat step S32 and step S33 until the nitrogen concentration measured at the interface of the second action pipeline 7 is greater than the preset nitrogen concentration value;

[0067] S35. After the nitrogen concentration measured at the interface of the second action pipeline 7 is greater than the preset nitrogen concentration value, close the first action control valve 61 and the second action control valve 71, and maintain the nitrogen pressure in the generator stator bar 1, the first action pipeline 6, and the second action pipeline 7 at the preset pressure value;

[0068] Wherein, when the nitrogen pressure in the generator stator bar 1, the first service pipeline 6 and the second service pipeline 7 is less than a predetermined pressure value, the first service control valve 61 is opened to supplement the nitrogen pressure to the preset pressure value;

[0069] S36. When it is necessary to stop the nitrogen maintenance, the first service control valve 61 and the second service control valve 71 are closed, and the nitrogen source is disassembled. That is, when the nuclear power plant's stator cooling water system finishes the overhaul and is ready to resume normal operation, it is necessary to stop the nitrogen maintenance at this time.

[0070] In this embodiment, the preset nitrogen concentration value is 98%, the preset pressure value is 0.5 MPa, and the predetermined pressure value is 0.2 MPa. Specifically, after the compressed air purging is completed, nitrogen charging maintenance is carried out on the generator stator bar 1. Since the generator stator bar 1 is made of copper and the pipelines in the nuclear power plant's stator cooling water system are made of stainless steel, mainly for maintaining the generator stator bar 1, the first reflux control valve 41 and the third input control valve 34 are closed, the nitrogen source is connected through the first service pipeline 6, the first service control valve 61 and the second service control valve 71 are opened, so that nitrogen is injected into the generator stator bar 1, and the nitrogen concentration is measured at the interface of the second service pipeline 7. Since the density of nitrogen is close to that of air, in order to prevent dead zones in the generator stator bar 1, that is, there are parts not covered by nitrogen, nitrogen pressure holding replacement needs to be carried out inside the generator stator bar 1. That is, the second service control valve 71 is closed, and the first service control valve 61 remains open, so that the nitrogen inside the generator stator bar 1 is filled to 0.5 MPa, then the first service control valve 61 is closed, and the second service control valve 71 is opened for exhaust. This process is repeated until the nitrogen concentration measured at the interface of the second service pipeline 7 is greater than 98%. Then the first service control valve 61 and the second service control valve 71 are closed, and the nitrogen pressure in the generator stator bar 1, the first service pipeline 6 and the second service pipeline 7 is maintained at 0.5 MPa. In actual operation, the nitrogen maintenance pressure of the generator stator bar 1 can be inspected every day. When the nitrogen pressure in the generator stator bar 1, the first service pipeline 6 and the second service pipeline 7 is less than 0.2 MPa, the first service control valve 61 is opened to supplement the nitrogen pressure to 0.5 MPa.

[0071] The method of nitrogen maintenance is to fill nitrogen into the equipment to isolate the equipment from contact with air, so as to achieve the purpose of slowing down corrosion, and its maintenance effect is related to the concentration of nitrogen. In the past, the nitrogen maintenance method for the generator stator bar 1 was to directly fill nitrogen at a certain pressure without replacing the internal air, resulting in more air remaining inside and poor maintenance effect. This maintenance method replaces the internal air during nitrogen maintenance and uses an instrument to measure and determine that the nitrogen concentration meets the requirements before carrying out nitrogen maintenance.

[0072] In addition, in step S3, when the nitrogen maintenance is interrupted, step S2 is executed. That is, when the maintenance of the generator stator bar 1 requires interruption of the nitrogen maintenance, the generator stator bar 1 is maintained by means of compressed air maintenance according to step S2. After the maintenance is completed, the nitrogen maintenance is resumed as soon as possible, and the resume process is executed according to step S3.

[0073] In step S4, cooling water is injected into the demineralized water tank 2, and a dosing pump is started to add sodium hydroxide to the cooling water, so that the conductivity of the cooling water after adding sodium hydroxide is greater than the preset conductivity value, and the pH value after adding sodium hydroxide is greater than the preset pH value, until the demineralized water system of the nuclear power plant completely resumes normal operation. In this embodiment, the preset conductivity value is 1 uS / cm, and the preset pH value is 8.5. Specifically, when the maintenance of the demineralized water system of the nuclear power plant is completed and the system needs to be resumed, the nitrogen maintenance is stopped. The demineralized water device 8 can be used to inject cooling water into the demineralized water tank 2, and the alkali addition tank 9 is used to add sodium hydroxide to the cooling water to make its conductivity greater than 1 uS / cm, so as to ensure that the pH of the cooling water is greater than 8.5 for wet maintenance of the generator stator bar 1 until the demineralized water system of the nuclear power plant resumes normal operation. During the wet maintenance of the generator stator bar 1, the demineralized water pump 32 is put into operation for one hour every day to evenly maintain the water and monitor the conductivity of the cooling water. If the requirements are not met, dosing adjustment needs to be carried out in time.

[0074] In summary, the maintenance method of the generator stator bar of the nuclear power plant formulates different maintenance methods according to different maintenance states of the generator stator bar 1, and maximally realizes the maintenance of the stator bar without affecting the progress of the maintenance. The maintenance method is divided into three stages. The first stage is compressed air maintenance to control the humidity inside the stator bar. The second stage is nitrogen maintenance. The third stage is dosing wet maintenance. The combined maintenance method of compressed air + nitrogen + wet maintenance can cover the entire outage maintenance process of the generator stator bar 1, and control standards are formulated for each maintenance method to ensure the maintenance effect, and the corrosion of the equipment is slowed down to the greatest extent. The nitrogen maintenance method is also optimized. When performing nitrogen maintenance, the internal air is replaced and measured with an instrument to ensure that the nitrogen concentration meets the requirements before performing nitrogen maintenance. At the same time, the compressed air maintenance steps are also optimized to ensure that all the residual water inside the generator stator bar 1 is dried, and to prevent the corrosion of the generator stator bar 1 caused by the residual water at the dead angle of one-way purging.

[0075] Understandably, the above embodiments only represent the preferred embodiments of the present invention, and the description thereof is relatively specific and detailed. However, it should not be construed as a limitation on the scope of the patent for the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, the above technical features can be freely combined, and several deformations and improvements can also be made, which all fall within the protection scope of the present invention. Therefore, all equivalent transformations and modifications made to the scope of the claims of the present invention shall fall within the scope covered by the claims of the present invention.

Claims

1. A cooling water system for a nuclear power plant, characterized in that: It comprises a generator stator bar (1), a stator cooling water tank (2), an input pipeline (3), a return pipeline (4), a branch pipeline (5), a first action pipeline (6), a second action pipeline (7), a compressed air source and a nitrogen source; The two ends of the input pipeline (3) are respectively connected to the output end of the stator cooling water tank (2) and the inlet end of the generator stator bar (1); the two ends of the return pipeline (4) are respectively connected to the input end of the stator cooling water tank (2) and the inlet end of the generator stator bar (1); and the two ends of the branch pipeline (5) are respectively connected to the interface end of the input pipeline (3) and the access end of the return pipeline (4); The first action pipeline (6) is connected to a first action end of the generator stator bar (1), and the second action pipeline (7) is connected to a second action end of the generator stator bar (1); The compressed air source is used to provide compressed air for the generator stator bar (1), and the nitrogen source is used to provide nitrogen for the generator stator bar (1). The compressed air source can be connected to the first working pipeline (6) or the second working pipeline (7), and the nitrogen source can be connected to the first working pipeline (6).

2. The nuclear power plant cooling water system according to claim 1, characterized in that: The nuclear power plant cooling water system further comprises a desalted water device (8) and an alkali adding tank (9), wherein the desalted water device (8) and the alkali adding tank (9) are both connected to the cooling water tank (2); A desalted water control valve (81) is provided between the desalted water device (8) and the constant cooling water tank (2); An alkali adding control valve (91) is provided between the alkali adding tank (9) and the constant cooling water tank (2).

3. The nuclear power plant cooling water system according to claim 1, characterized in that: The nuclear power plant cooling water system further comprises a discharge pipeline (10) connected to the discharge end of the cooling water tank (2), and a discharge control valve (101) is provided on the discharge pipeline (10).

4. The nuclear power plant cooling water system according to claim 1, characterized in that: The first action pipeline (6) is provided with a first action control valve (61); The second action pipeline (7) is provided with a second action control valve (71); A first input control valve (31), a cooling water pump (32), a second input control valve (33) and a third input control valve (34) are sequentially arranged on the input pipeline (3) along the fluid input direction; The reflux pipeline (4) is provided with a first reflux control valve (41) and a second reflux control valve (42) in sequence along the fluid input direction; The branch pipeline (5) is provided with a branch control valve (51).

5. A method for maintaining a stator bar of a nuclear power plant generator, used for maintaining a stator bar (1) of a nuclear power plant generator when a stator cooling water system of the nuclear power plant is under maintenance, based on the stator cooling water system of the nuclear power plant according to any one of claims 1 to 4, characterized in that: Includes steps: S1. Discharging cooling water from the cooling water system of the nuclear power plant; S2, blowing the generator stator bars (1) with compressed air; S3, performing nitrogen maintenance on the generator stator wire bar (1); S4, performing wet maintenance on the generator stator wire rod (1) by adding chemicals.

6. The maintenance method for stator bars of a nuclear power plant generator according to claim 5, characterized in that: In step S1, when the cooling water system of a nuclear power plant needs to be overhauled, the cooling water pump (32) is shut down, and the first input control valve (31), the second input control valve (33), the third input control valve (34), the discharge control valve (101), the first reflux control valve (41), the second reflux control valve (42), the second action control valve (71) and the first action control valve (61) are opened.

7. The maintenance method for stator bars of a nuclear power plant generator according to claim 5, characterized in that: Step S2 includes: S21, closing the first input control valve (31), the second input control valve (33), the third input control valve (34), the first return flow control valve (41), the second return flow control valve (42) and the discharge control valve (101); S22, connecting the compressed air source via the first working pipeline (6); S23, opening the second action control valve (71) and the first action control valve (61), measuring the humidity of the discharged compressed air at the interface of the second action pipeline (7), until the humidity of the compressed air at the interface of the second action pipeline (7) is less than a preset humidity value, and maintaining continuous purging and maintenance of the compressed air for a certain period of time; S24, after maintaining the compressed air continuous purge maintenance for a certain period of time, using the second working pipeline (7) to connect to the compressed air source, and measuring the humidity of the discharged compressed air at the interface of the first working pipeline (6), until the humidity of the compressed air at the interface of the first working pipeline (6) is less than a preset humidity value, and the compressed air continuous purge maintenance is maintained for a preset time; S25. After the compressed air purge is completed, close the first action control valve (61) and the second action control valve (71) and disassemble the compressed air source.

8. The maintenance method for stator bars of a nuclear power plant generator according to claim 5, characterized in that: Step S3 includes: S31, closing the first reflux control valve (41) and the third input control valve (34), connecting the nitrogen source via the first working pipeline (6), opening the first working control valve (61) and the second working control valve (71), allowing nitrogen to be injected into the generator stator bar (1), and measuring the nitrogen concentration at the interface of the second working pipeline (7); S32, closing the second action control valve (71), and keeping the first action control valve (61) open, so that the internal nitrogen of the generator stator bar (1) is filled to a preset pressure value; S33, closing the first action control valve (61), and opening the second action control valve (71) to exhaust; S34, repeating step S32 and step S33 until the nitrogen concentration measured at the interface of the second action pipeline (7) is greater than a preset nitrogen concentration value; S35, when the nitrogen concentration measured at the interface of the second working pipeline (7) is greater than a preset nitrogen concentration value, the first working control valve (61) and the second working control valve (71) are closed to maintain the nitrogen pressure in the generator stator bar (1), the first working pipeline (6) and the second working pipeline (7) at a preset pressure value; When the nitrogen pressure in the generator stator bar (1), the first action pipeline (6) and the second action pipeline (7) is less than a predetermined pressure value, the first action control valve (61) is opened to replenish the nitrogen pressure to the preset pressure value; S36. When it is necessary to stop nitrogen maintenance, close the first function control valve (61) and the second function control valve (71), and disassemble the nitrogen source.

9. The maintenance method for stator bars of a nuclear power plant generator according to claim 8, characterized in that: In step S3, when the nitrogen maintenance is interrupted, step S2 is executed.

10. The maintenance method for stator bars of a nuclear power plant generator according to claim 5, characterized in that: In step S4, cooling water is injected into the cooling water tank (2), and a dosing pump is started to add sodium hydroxide to the cooling water, so that the conductivity of the cooling water after the addition of sodium hydroxide is greater than a preset conductivity value, and the pH value after the addition of sodium hydroxide is greater than a preset pH value, until the cooling water system of the nuclear power plant is fully restored to normal operation.

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