A fast reactor main feedwater system

Abstract

The present application relates to a kind of fast reactor main feedwater system.The fast reactor main feedwater system provided by the present application can ensure the water supply flow of each main feedwater module to steam generator consistent by adjusting the module regulating valve of each main feedwater module;At the same time, different water supply flow can be provided by adjusting valve group according to the power state of power plant, and the main feedwater flow regulating accuracy is ensured.In addition, when steam generator leaks, the present application can prevent water from continuing to enter the steam generator by closing the downstream isolation valve and the quick isolation valve of the module regulating valve, and then by opening the first post-accident drain valve and the second post-accident drain valve, the water in the steam generator can be drained, and the consequences of sodium-water reaction can be slowed down, thereby meeting the operation requirements of fast reactor nuclear power plant.

Description

Technical Field

[0001] This invention belongs to the field of system design technology for high-temperature and high-pressure piping systems in nuclear power plants, specifically relating to a fast reactor main feedwater system. Background Technology

[0002] The main feedwater system is of great importance to the operation of fast reactor nuclear power plants. Its main function is to supply high-pressure feedwater heated by high-pressure heaters to the steam generator.

[0003] In existing fast reactor nuclear power plants in China, each reactor has 16 identical steam generators. With the current system layout, it is difficult to guarantee that each steam generator receives the same flow of feedwater. Furthermore, damage to the heat transfer tubes of the steam generators in sodium-cooled fast neutron reactor nuclear power plants can lead to violent chemical reactions when sodium comes into contact with water or steam, including temperature increases, deflagration, and luminescence, which can affect the operation of the fast reactor nuclear power plant. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide a fast reactor main feedwater system that maintains the same feedwater flow rate for each module through system design. Furthermore, it can quickly isolate and drain the steam generator after a sodium water leak occurs, thereby ensuring that each steam generator receives the same flow rate of feedwater. Simultaneously, it minimizes the impact of sodium water leaks from the steam generator on the operation of the fast reactor nuclear power plant, ensuring the long-term stability of the system.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is: a fast reactor main feedwater system, comprising:

[0006] Main feed jellyfish pipe;

[0007] There are 16 main water supply modules, each of which includes a module water supply pipeline. Along the water supply direction, an orifice flow meter, an upstream isolation valve of the module regulating valve, a module regulating valve, and a downstream isolation valve of the module regulating valve are connected in series on the module water supply pipeline.

[0008] Two loops are connected in parallel to the outlet end of the main water supply header. Each loop includes a main water supply loop pipe. A Venturi flow meter and a regulating valve group are sequentially installed on the main water supply loop pipe along the water supply direction. Each loop connects to 8 main water supply modules. The 8 main water supply modules are sequentially installed downstream of the regulating valve group along the water supply direction.

[0009] Furthermore, each loop also includes a differential pressure measuring device, the two ends of which are respectively connected to the upstream and downstream pipelines of the regulating valve group.

[0010] Furthermore, during fast reactor operation, the pressure difference across the regulating valve group is maintained between 1.0 and 1.1 MPa.

[0011] Furthermore, the regulating valve group includes: a loop regulating valve group and a bypass regulating valve group, wherein the loop regulating valve group and the bypass regulating valve group are connected in parallel on the main water supply loop pipeline;

[0012] The loop regulating valve group includes, along the water supply direction, an upstream electric isolation valve, a main water supply loop regulating valve, and a downstream electric isolation valve connected in series.

[0013] The bypass regulating valve group includes, in the direction of water supply, an upstream electric isolation valve for the bypass regulating valve, a main water supply bypass regulating valve, and a downstream electric isolation valve for the bypass regulating valve, connected in series.

[0014] Furthermore, when the power plant is in a low-power state below 28% of its rated power, the main feedwater loop regulating valve is closed, and the feedwater flow rate is adjusted through the main feedwater bypass regulating valve.

[0015] Furthermore, when the power plant is in a high-power state of 28% or more of its rated power, the main feedwater bypass regulating valve maintains a fixed opening, and the feedwater flow rate is regulated by the main feedwater loop regulating valve.

[0016] Furthermore, each of the main water supply modules is connected to the loop through the first end of the module water supply pipe and to the corresponding steam generator through the second end of the module water supply pipe;

[0017] On the module water supply pipeline, downstream of the isolation valve of the module regulating valve, a quick isolation valve, a module pressure measuring device, and a module temperature measuring device are connected in series along the water supply direction.

[0018] Furthermore, each of the main water supply modules also includes an emergency drainage pipe, the first end of which is connected to the module water supply pipe and is located downstream of the quick isolation valve.

[0019] Furthermore, a first drainage valve and a second drainage valve are connected in series on the post-accident drainage pipe.

[0020] Furthermore, if a steam generator leaks, the downstream isolation valve and the quick isolation valve of the module regulating valve are closed, and the first drain valve and the second drain valve after an accident are opened.

[0021] The beneficial effects of this invention are as follows: The fast reactor main feedwater system provided by this invention ensures consistent feedwater flow to the steam generator by adjusting the module regulating valves of each main feedwater module. Simultaneously, it allows for different feedwater flow rates to be provided through the regulating valve group according to the power plant's operating status, while maintaining the accuracy of main feedwater flow regulation. Furthermore, in the event of a steam generator leak, the fast reactor main feedwater system provided by this invention prevents feedwater from continuing to enter the steam generator by closing the downstream isolation valve and the quick isolation valve of the module regulating valve. Then, by opening the first and second post-accident drain valves, the water remaining in the steam generator can be drained, mitigating the consequences of the sodium-water reaction and thus meeting the operational requirements of the fast reactor nuclear power plant. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of a fast reactor main feedwater system provided by an embodiment of the present invention;

[0023] In the diagram: 1-Main water supply header, 2-Main water supply loop pipe, 3-Venturi flow meter, 4-Main water supply loop regulating valve, 5-Main water supply bypass regulating valve, 6-Upstream electric isolation valve of loop regulating valve, 7-Downstream electric isolation valve of loop regulating valve, 8-Upstream electric isolation valve of bypass regulating valve, 9-Downstream electric isolation valve of bypass regulating valve, 10-Differential pressure measuring device, 11-Orifice plate flow meter, 12-Upstream isolation valve of module regulating valve, 13-Module regulating valve, 14-Downstream isolation valve of module regulating valve, 15-Quick isolation valve, 16-Module water supply pipe, 17-Module pressure measuring device, 18-Module temperature measuring device, 19-Post-accident drainage pipe, 20-First post-accident drainage valve, 21-Second post-accident drainage valve. Detailed Implementation

[0024] To enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be further clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0025] like Figure 1 As shown in the figure, an embodiment of the present invention provides a fast reactor main feedwater system, the system comprising: a main feedwater header 1, two loops, and 16 main feedwater modules; the two loops are connected in parallel to the outlet end of the main feedwater header 1, and each loop connects to 8 of the main feedwater modules.

[0026] Feedwater enters the fast reactor main feedwater system through the inlet end of the main feedwater header 1, then flows through the loop into the main feedwater module, and finally into the steam generator. To ensure the operating efficiency of the fast reactor nuclear power plant, the design pressure of the fast reactor main feedwater system is 22.9 MPa, and the design temperature is 230°C.

[0027] The two loops are designated as Loop I and Loop II, which are connected in parallel at the outlet end of the main feedwater header 1. Each loop has the same configuration, including a main feedwater loop pipe 2, a Venturi flow meter 3, a regulating valve assembly, and a differential pressure measuring device 10. The Venturi flow meter 3 and the regulating valve assembly are sequentially installed along the feedwater direction on the main feedwater loop pipe 2. The two ends of the differential pressure measuring device 10 are connected to the upstream and downstream pipes of the regulating valve assembly, respectively. The differential pressure measuring device 10 monitors the operation of the regulating valve assembly by measuring the pressure difference across the regulating valve assembly. During fast reactor operation, the pressure difference across the regulating valve assembly is maintained between 1.0 and 1.1 MPa.

[0028] The regulating valve assembly includes a loop regulating valve assembly and a bypass regulating valve assembly, which are connected in parallel on the main feedwater loop pipeline 2. The loop regulating valve assembly, along the feedwater direction, includes, in series, an upstream electrically operated isolation valve 6, a main feedwater loop regulating valve 4, and a downstream electrically operated isolation valve 7. The bypass regulating valve assembly, along the feedwater direction, includes, in series, an upstream electrically operated isolation valve 8, a main feedwater bypass regulating valve 5, and a downstream electrically operated isolation valve 9. When the power plant is in a low-power state (below 28% of rated power), the required feedwater flow is small. To ensure the accuracy of the main feedwater flow regulation, the main feedwater loop regulating valve 4 is closed, and only the main feedwater bypass regulating valve 5 is used to regulate the feedwater flow. When the power plant is in a high-power state (above 28% of rated power), the main feedwater bypass regulating valve 5 maintains a fixed opening, and the feedwater flow is regulated through the main feedwater loop regulating valve 4, thereby ensuring the accuracy of the main feedwater flow regulation. The upstream electric isolating valve 6 and the downstream electric isolating valve 7 of the loop control valve are used for maintenance of the main feedwater loop control valve 4. During maintenance, closing the upstream electric isolating valve 6 and the downstream electric isolating valve 7 allows for maintenance or replacement of the main feedwater loop control valve 4. Similarly, the upstream electric isolating valve 8 and the downstream electric isolating valve 9 of the bypass control valve are used for maintenance of the main feedwater bypass control valve 5. During maintenance, closing the upstream electric isolating valve 8 and the downstream electric isolating valve 9 allows for maintenance or replacement of the main feedwater bypass control valve 5.

[0029] Sixteen main feedwater modules are evenly distributed across two loops, with eight main feedwater modules connected to each loop. On each loop, the eight main feedwater modules are sequentially positioned downstream of the regulating valve assembly along the feedwater direction. Each main feedwater module includes an orifice flow meter 11, an upstream isolation valve 12, a regulating valve 13, a downstream isolation valve 14, a quick isolation valve 15, a feedwater pipeline 16, a pressure measuring device 17, a temperature measuring device 18, an emergency drainage pipeline 19, a first emergency drainage valve 20, and a second emergency drainage valve 21. The orifice flow meter 11, the upstream isolation valve 12, the regulating valve 13, the downstream isolation valve 14, the quick isolation valve 15, the pressure measuring device 17, and the temperature measuring device 18 are connected in series on the feedwater pipeline 16 along the feedwater direction. Each main feedwater module is connected to one loop via the first end of the feedwater pipeline 16 and to a corresponding steam generator via the second end of the feedwater pipeline 16. The first end of the post-accident drainage pipe 19 is connected to the module water supply pipe 16, and the first end of the post-accident drainage pipe 19 is located downstream of the quick isolation valve 15 (i.e., between the quick isolation valve 15 and the module pressure measuring device 17); the second end of the post-accident drainage pipe 19 is connected to the water supply and drainage pipeline. The first post-accident drainage valve 20 and the second post-accident drainage valve 21 are connected in series on the post-accident drainage pipe 19. The module regulating valve 13 is used to ensure consistent flow rates for the 16 main water supply modules, and the orifice flow meter 11 is used to measure the flow rate of each main water supply module. The upstream isolation valve 12 and the downstream isolation valve 14 of the module regulating valve are used for maintenance of the module regulating valve 13. During maintenance, closing the upstream isolation valve 12 and the downstream isolation valve 14 allows for maintenance or replacement of the module regulating valve 13. The orifice plate flow meter 11, module pressure measuring device 17, and module temperature measuring device 18 are used to monitor the operation of each main water supply module. If the flow rate, temperature, or pressure of a certain main water supply module deviates from the preset operating value or is inconsistent with the other main water supply modules, the main water supply module can be isolated for maintenance.

[0030] In the event of a steam generator leak, the downstream isolation valve 14 and the quick isolation valve 15 of the module regulating valve are closed to isolate the leak and prevent feedwater from continuing to enter the steam generator. The closing time of the downstream isolation valve 14 is less than or equal to 15 seconds, and the closing time of the quick isolation valve 15 is less than or equal to 3 seconds, effectively preventing feedwater from entering the steam generator. After isolation, the first drain valve 20 and the second drain valve 21 after the accident are opened to drain the water remaining in the steam generator, thereby mitigating the sodium-water reaction. Therefore, the post-accident drain pipe 19 must be located downstream of the quick isolation valve 15 to ensure that water remaining in the steam generator can still be drained after feedwater is isolated.

[0031] The fast reactor main feedwater pipeline system provided by this invention can ensure consistent feedwater flow to the steam generator from each main feedwater module through the module regulating valve 13 on each main feedwater module. It can provide different feedwater flow rates according to the power state of the power plant through the regulating valve group, while ensuring the accuracy of the main feedwater flow regulation. Furthermore, in the event of a steam generator leak, closing the downstream isolation valve 14 and the quick isolation valve 15 of the module regulating valve can prevent feedwater from continuing to enter the steam generator. Then, opening the first post-accident drain valve 20 and the second post-accident drain valve 21 can drain the water remaining in the steam generator, mitigating the consequences of the sodium-water reaction and thus meeting the operational requirements of the fast reactor nuclear power plant.

[0032] The methods described in this invention are not limited to the specific embodiments described above. The embodiments described are merely illustrative examples of this invention, and the invention can also be implemented in other specific ways or forms without departing from its spirit or essential characteristics. Therefore, the described embodiments should be considered illustrative rather than limiting in any respect. The scope of this invention should be defined by the appended claims, and any variations equivalent to the intent and scope of the claims should also be included within the scope of this invention.

Claims

1. A fast reactor main feedwater system, characterized in that, include: Main feed jellyfish pipe; There are 16 main water supply modules, each of which includes a module water supply pipeline. Along the water supply direction, an orifice flow meter, an upstream isolation valve of the module regulating valve, a module regulating valve, and a downstream isolation valve of the module regulating valve are connected in series on the module water supply pipeline. Two loops are connected in parallel to the outlet end of the main water supply header. Each loop includes a main water supply loop pipe. A Venturi flow meter and a regulating valve group are sequentially installed on the main water supply loop pipe along the water supply direction. Each loop connects to 8 main water supply modules. The 8 main water supply modules are sequentially installed downstream of the regulating valve group along the water supply direction. Each loop also includes a differential pressure measuring device, the two ends of which are respectively connected to the upstream and downstream pipelines of the regulating valve group; The regulating valve group includes: a loop regulating valve group and a bypass regulating valve group, wherein the loop regulating valve group and the bypass regulating valve group are connected in parallel on the main water supply loop pipeline; The loop regulating valve group includes, along the water supply direction, an upstream electric isolation valve, a main water supply loop regulating valve, and a downstream electric isolation valve connected in series. The bypass regulating valve group includes, in the direction of water supply, an upstream electric isolation valve for bypass regulating valve, a main water supply bypass regulating valve, and a downstream electric isolation valve for bypass regulating valve, connected in series. Each of the main water supply modules is connected to the loop through the first end of the module water supply pipe and to the corresponding steam generator through the second end of the module water supply pipe; On the module water supply pipeline, downstream of the isolation valve downstream of the module regulating valve, a quick isolation valve, a module pressure measuring device, and a module temperature measuring device are connected in series along the water supply direction. Each of the main water supply modules also includes an emergency drainage pipe, the first end of which is connected to the module water supply pipe and is located downstream of the quick isolation valve. The post-accident drainage pipeline is equipped with a first post-accident drainage valve and a second post-accident drainage valve connected in series.

2. The fast reactor main feedwater system according to claim 1, characterized in that, During fast reactor operation, the pressure difference across the regulating valve group is maintained between 1.0 and 1.1 MPa.

3. The fast reactor main feedwater system according to claim 1, characterized in that, When the power plant is in a low-power state below 28% of its rated power, the main feedwater loop regulating valve is closed, and the feedwater flow rate is regulated by the main feedwater bypass regulating valve.

4. The fast reactor main feedwater system according to claim 1, characterized in that, When the power plant is in a high-power state of more than 28% of its rated power, the main feedwater bypass regulating valve maintains a fixed opening, and the feedwater flow is regulated by the main feedwater loop regulating valve.

5. The fast reactor main feedwater system according to claim 1, characterized in that, If a steam generator leaks, the downstream isolation valve and the quick isolation valve of the module regulating valve shall be closed, and the first drain valve and the second drain valve after an accident shall be opened.

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