Sodium fire suppression type outer sleeve and installation method thereof

Abstract

The invention belongs to the technical field of sodium-cooled fast reactors, aims to solve the problem of sodium fire coping in high and large spaces, and discloses a sodium fire suppression type outer sleeve and a mounting method thereof.The sodium fire suppression type outer sleeve comprises a shell formed by splicing two half shells, supporting blocks are mounted on the inner wall of the shell, and flow guide grooves are formed in the half shells; the flow guide groove is connected with a drainage pipe to guide out leaked sodium, a sealing strip is arranged at the joint of the two half shells to achieve annular sealing, and a sealing ring is arranged between the two sodium fire suppression type outer sleeves to achieve axial sealing. The sodium fire suppression type outer sleeves are installed in a modular mode, the two half shells are installed on the process pipeline, the sealing strips and the sealing rings are installed, the multiple sodium fire suppression type outer sleeves are installed outside the process pipeline, and leaked sodium is guided out through the flow guide grooves and the drainage pipes. The device has the functions of collecting leaked sodium and guiding flow, and the sodium fire suppression type outer sleeve is designed in a modular mode, can be disassembled quickly and is convenient to install, check and maintain.

Description

Technical Field

[0001] The present application belongs to the technical field of sodium-cooled fast reactors, and in particular relates to a sodium fire suppression outer sleeve and an installation method thereof. Background Art

[0002] The primary and secondary main cooling systems, accident heat removal systems, and related auxiliary sodium systems of the sodium-cooled fast reactor utilize metallic sodium as their working medium. The primary main cooling system's equipment is housed in a sodium pool containing over 1,000 tons of sodium, providing significant thermal inertia to cope with accident conditions. The boiling point of sodium at standard atmospheric pressure is 882.9°C, and the primary main cooling system can reach temperatures exceeding 500°C, resulting in efficient heat transfer and significantly higher steam parameters than thermal reactors. This gives sodium-cooled fast reactors a clear advantage in inherent safety and power generation efficiency over thermal reactors. Due to the reactive nature of sodium metal, sodium leaking into the air can cause sodium fires, making the prevention, detection, spread prevention, and extinguishing of sodium fires extremely important.

[0003] The current design idea is to adopt different solutions according to the different areas where the sodium pipelines are located.

[0004] In smaller process rooms, single-layer piping is used, with sodium leak detection wires installed on the outer walls. The room is equipped with photoelectric smoke fire alarm detectors, aerosol detectors, thermocouples, and other instruments. The floor and walls are covered with steel cladding, and a sodium receiving pan is placed on the steel cladding. If a sodium leak occurs, the relevant instruments generate an alarm signal and close the valves before and after the leak point to isolate it. The leaked sodium burns as it drips from the air, then gradually flows into the sodium receiving pan. The specially designed sodium receiving pan prevents the sodium from burning once it enters the pan. If a sodium leak occurs, the room's normal ventilation and exhaust systems are shut down, the emergency smoke exhaust system is activated, and the nitrogen flooding system is activated to inject nitrogen into the room, reducing the room's oxygen content and ultimately extinguishing the sodium fire.

[0005] In high and large spaces, such as the reactor hall, the reliability of photoelectric smoke detectors, aerosol detectors, and thermocouples as alarm signals is insufficient due to the large space. Controlled ventilation and nitrogen injection are infeasible to reduce oxygen concentrations. The secondary main cooling system and residual heat removal system lack valves in this area, making it impossible to isolate the leak by closing them. If sodium leaks were collected using a sodium pan on the ground, due to the height and size of the space, a large-scale mist fire would form before the sodium could be collected. This fire would significantly increase temperature and pressure, potentially causing the failure of redundant nuclear safety features in the hall—an unacceptable consequence. Currently, sodium fire prevention in such areas relies on a "blocking" approach, employing a double-layered pipe structure with inner and outer pipes. In the event of an inner pipe leak, sodium flows into the annular cavity between the two pipes. The outer pipe, as the boundary for containing the sodium, must maintain its integrity and sealing, and its thickness must meet structural requirements. This requires that both the inner pipe and the outer pipe be designed to meet nuclear safety standards. The design must consider the relative position of the inner and outer pipe welds, as well as the distance between the liner ring and the weld, to ensure installation feasibility. In the prefabrication workshop, the liner is welded to the outer wall of the inner pipe. During on-site installation, the order of installation of each section of the inner and outer pipe must be arranged according to the location of the welds and the on-site construction space, resulting in low construction efficiency. The pipeline force is transmitted to the support bracket through the liner and outer pipe. The outer pipe serves as a load-bearing structural component and needs to contain sodium leakage. Its thickness and pressure-bearing capacity must meet mechanical requirements, resulting in high technical requirements and high cost for the outer pipe. If the inner pipe leaks and needs to be inspected and replaced, the outer pipe must be cut open first, which makes it difficult to maintain. Therefore, adopting this solution is relatively costly, with high construction difficulty and high economic costs.

[0006] Therefore, for sodium fire prevention in high and large spaces, if a small process room solution is used, sodium fire detection and isolation functions cannot be reliably achieved, and nuclear safety functions may fail. If a double-layer piping solution is used, its design and construction are difficult, and its economic efficiency and maintainability are poor. Improving economic efficiency is the guarantee for the large-scale development of sodium-cooled fast reactors. The above two solutions cannot meet the requirements, and new sodium fire prevention solutions need to be developed. Summary of the Invention

[0007] The main purpose of this application is to provide a sodium fire suppression outer casing to solve the problem of dealing with sodium fires in high and large spaces. Its construction convenience, maintainability and economy are significantly better than the existing double-layer pipe solution.

[0008] Another object of the present application is to provide a method for installing a sodium fire suppression type outer sleeve, which adopts modular installation and flexibly determines the length of the outer sleeve module according to the pipeline network layout. The various outer sleeve modules are connected by axial quick locking components, making installation and disassembly more convenient.

[0009] In order to achieve the above objectives, this application provides the following technical solutions:

[0010] In the first aspect, the present application provides a sodium fire suppression outer sleeve, comprising a shell formed by splicing two half shells, a support block being installed on the inner wall of the shell, a guide groove being installed on the half shell, and a drainage pipe being connected to the guide groove to drain out leaked sodium; a sealing strip is provided at the connection between the two half shells to achieve annular sealing; a sealing ring is provided between the two sodium fire suppression outer sleeves to achieve axial sealing.

[0011] In some embodiments, a branch pipe seat is installed on the outer wall of the shell, and a hole is opened at the connection between the shell and the branch pipe seat, and the cable is led out from the branch pipe seat.

[0012] In some embodiments, the connection between the two half shells is an adaptive step structure, and the sealing strip is installed on the step structure.

[0013] In some embodiments, the connection between the two sodium fire suppression type outer sleeves is an adaptive step structure, and the sealing ring is installed on the step structure.

[0014] In some embodiments, the two half-shells are circumferentially locked together by a locking ring quick-locking assembly and pressure is applied to the sealing strip to achieve circumferential sealing.

[0015] In some embodiments, the two sodium fire suppression type outer sleeves are axially locked by locking the axial quick locking assembly and applying pressure to the sealing ring to achieve axial sealing.

[0016] In some embodiments, the half shell is a semi-cylindrical shell structure.

[0017] In some embodiments, the support blocks are evenly arranged along the circumferential direction.

[0018] In some embodiments, the guide groove and the half shell are integrally formed, or the guide groove and the half shell are welded.

[0019] In a second aspect, the present application provides a method for installing the sodium fire suppression outer casing, which adopts a modular installation method, comprising:

[0020] Bending a portion of the half shell to form a guide groove, or welding the separately produced guide groove to connect the half shell;

[0021] Connecting the drainage pipe to the lower side of the guide groove; installing a plurality of support blocks on the inner wall of the shell;

[0022] According to the layout of the pipe network, a number of the sodium fire suppression outer sleeves are selected, the sodium fire suppression outer sleeves are installed on the process pipes, and the pipes are laid out;

[0023] Installing a sealing strip, circumferentially locking the two half-shells and applying pressure to the sealing strip to achieve circumferential sealing;

[0024] Installing a sealing ring, axially locking the two sodium fire suppression outer sleeves and applying pressure to the sealing ring to achieve axial sealing;

[0025] A plurality of sodium fire suppression type outer sleeves are installed outside the process pipeline. When sodium leakage occurs in the process pipeline, the leaked sodium is discharged through the guide groove and the drainage pipe.

[0026] Compared with the prior art, the sodium fire suppression outer casing and the installation method thereof provided by the present application have the following beneficial effects:

[0027] The sodium fire suppression outer casing provided in this application collects and diverts sodium leaks. Its modular design allows for quick disassembly, facilitating installation, inspection, and maintenance. Because it is not located in the force transmission path of the pipe supports and hangers, it requires less strength and can utilize more economical materials and thicknesses.

[0028] The sodium fire suppression outer casing adopts a modular design, allowing flexible module lengths based on the pipe network layout. Each outer casing module is connected via axial quick-lock assemblies, making installation and disassembly easy. All module components can be connected in the prefabrication workshop. On-site installation requires only laying out the wiring, positioning the modules, installing the sealing rings and strips, and tightening the locking assemblies. There is no welding or hot work involved, resulting in fast and environmentally friendly construction.

[0029] The sodium fire suppression outer casing is airtight, containing leaking sodium and preventing it from escaping from high altitudes. This effectively prevents the occurrence of sodium fire mist, significantly mitigating the consequences of accidents. Furthermore, compared to existing double-tube designs, since this outer casing only collects and diverts leaked sodium without considering pressure bearing capacity, more economical materials and thicknesses can be selected, resulting in better cost-effectiveness and easier construction.

[0030] Compared to the stainless steel insulation casings commonly found in existing nuclear power plants, the sodium fire suppression outer casing provides sealing, flow diversion, cable routing, and space for sodium aerosol detection instrumentation. Compared to existing double-layer outer tubes, the sodium fire suppression outer casing is significantly thinner. In the event of a sodium leak, the sodium is directed into the sodium receiving tray through the sodium fire suppression outer casing's diversion grooves and diversion tubes. This is a controllable method, collecting the leaked sodium within a manageable range. A small amount of sodium fire may occur on the surface of the sodium receiving tray, but this is an acceptable consequence.

[0031] This application uses a collection and drainage method to solve sodium leakage, overcoming the problems of cumbersome installation, poor maintainability and cost caused by the existing "blocking" method using a double-layer tube structure. After the sodium flows out, this application can reliably collect and guide it to where it needs to go. At the same time, the guide groove of the sodium fire suppression outer sleeve of this application can provide installation space for a sodium aerosol detection instrument, which can achieve early leakage detection by detecting the sodium element concentration in the guide groove.

[0032] The installation method of the sodium fire suppression outer sleeve provided in this application adopts modular installation. The length of the outer sleeve module is flexibly determined according to the pipeline network layout. The various outer sleeve modules are connected by axial quick locking components, making installation and disassembly more convenient. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solution of this application, the following is a brief introduction to the drawings required for the technical description.

[0034] Figure 1 A schematic structural diagram of a sodium fire suppression outer sleeve provided in an embodiment of the present application;

[0035] Figure 2 A left side view of a sodium fire suppression outer sleeve provided in an embodiment of the present application;

[0036] Figure 3 A front view of a sodium fire suppression outer sleeve provided in an embodiment of the present application;

[0037] Figure 4 A partial view of a sodium fire suppression outer sleeve provided in an embodiment of the present application, showing the structure of the annular quick locking assembly;

[0038] Figure 5 A partial view of a sodium fire suppression outer sleeve provided in an embodiment of the present application, showing the structure of the axial quick locking assembly.

[0039] Description of reference numerals:

[0040] 1-half shell; 2-guide groove; 3-drainage pipe; 4-annular quick locking assembly; 5-sealing strip; 6-support block; 7-sealing ring; 8-axial quick locking assembly; 9-branch seat. DETAILED DESCRIPTION

[0041] The following is further explained in detail through specific implementation methods.

[0042] The design idea of ​​this application is to collect and divert leaked sodium to prevent it from producing mist-like sodium fire in high and large spaces. This solution is mainly achieved through a sodium fire suppression outer casing.

[0043] like Figures 1 to 5 As shown, an embodiment of the present application provides a sodium fire suppression outer sleeve, including a shell, a guide groove 2, a drainage pipe 3, a sealing strip 5, a support block 6, a sealing ring 7, a branch pipe seat 9, and a quick locking assembly. The shell is spliced ​​together by two half shells 1, and the half shell 1 is a semi-cylindrical shell structure. The quick locking assembly includes an annular quick locking assembly 4 and an axial quick locking assembly 8. The sodium fire suppression outer sleeve is installed on the outside of the inner pipe. Under the condition of leakage of the inner pipe, the leaking sodium is contained by the sodium fire suppression outer sleeve of this embodiment and is introduced into the sodium receiving tray or storage tank through the guide groove 2 and the drainage pipe 3 to achieve the containment of the leaking sodium, thereby suppressing the sodium fire.

[0044] The sodium fire suppression type outer sleeve adopts a modular design. According to the layout of the pipeline network, the length of the outer sleeve module can be flexibly determined. The outer sleeve modules are connected by an axial quick locking assembly 8, which has the characteristics of convenient installation and disassembly. The various components on the outer sleeve module can be connected in the prefabrication workshop. The on-site installation work only needs to complete the simple tasks of laying out the lines, positioning the modules, installing the sealing rings 7 and the sealing strips 5, and overlapping the quick locking assemblies. There is no welding or hot work, the construction speed is fast, and the construction environment is friendly. If there is any damage, just replace the damaged outer sleeve module, and the remaining outer sleeve modules do not need to be replaced. Compared with the existing double-layer outer tube, the outer sleeve module provided by this application does not need to be cut and replaced, and there is no welding operation during restoration.

[0045] The two half-shells 1 overlap to form a single shell, which is then completed by a quick-lock assembly. Cooperating steps are provided in the axial and circumferential directions, on which sealing strips 5 and sealing rings 7 are mounted. The quick-lock assembly seals the shell. The sodium fire suppression outer casings are connected by a matching overlap structure. This design decouples the installation sequence of the inner and outer tubes and eliminates the conventional outer tube welding and non-destructive testing, significantly improving construction efficiency.

[0046] The two half shells 1 are overlapped by matching steps, and a sealing strip 5 is set at the connection between the two half shells 1. The two half shells 1 are combined into a cylinder through the locking ring quick locking component 4 and pressure is applied to the sealing strip 5 to achieve sealing. The structure of the annular quick locking component 4 is as follows Figure 4 As shown, it is an existing locking structure. A mature product is selected according to the specific locking requirements, which will not be described here.

[0047] The two sodium fire suppression outer sleeves are overlapped by matching steps, and a sealing ring 7 is set at the overlap. The two sodium fire suppression outer sleeves are connected by locking the axial quick locking assembly 8 and applying pressure to the sealing ring 7 to achieve sealing. The axial quick locking assembly 8 of the two adjacent sodium fire suppression outer sleeves is used to connect the two sodium fire suppression outer sleeves together in the axial direction. The structure of the axial quick locking assembly 8 is as follows: Figure 5 As shown, it is an existing locking structure. A mature product is selected according to the specific locking requirements, which will not be described here.

[0048] When installing the quick locking assembly, first lock the annular quick locking assembly 4, and then lock the axial quick locking assembly 8. When disassembling, first loosen the axial quick locking assembly 8, and then loosen the annular quick locking assembly 4.

[0049] A branch pipe seat 9 is provided on the shell as a cable lead-out channel, which can lead out cables for electric heating, sodium leakage detection, thermocouple, and sodium aerosol detection instruments. The cables are arranged between the inner tube and the sodium fire suppression outer tube.

[0050] In one embodiment, the sodium fire suppression outer sleeve is designed as a simple structure and is directly wrapped around the insulation layer.

[0051] In one embodiment, the sodium fire suppression outer casing is designed as a support structure. Metal support blocks 6 are welded within the casing. The outer casing is thickened to accommodate pipe supports or dampers. Multiple support blocks 6 can be arranged circumferentially. Heating wires, leak detection wires, thermocouples, and other devices can be installed between the support blocks 6, and insulation material can be filled in. The arrangement of the support blocks 6 can be determined based on the number of pipe supports or dampers. Specifically, as many groups of support blocks 6 as there are pipe supports or dampers in the axial direction, each group of support blocks 6 is evenly spaced circumferentially. The number and size of the support blocks 6 are determined based on the load conditions.

[0052] A diversion trough 2 is installed at the bottom of each sodium fire suppression outer casing. This diversion trough 2 serves as a guide in the event of sodium leaks from the inner pipe and provides space for installing sodium aerosol detection instruments. This trough 2 is installed at the bottom of the sodium fire suppression outer casing in the horizontal section of the pipe network. A drainage pipe 3 connects to the bottom of the trough 2, directing the leaked sodium to a sodium receiving tray or storage tank.

[0053] When the sodium fire suppression type outer casing is installed on a horizontal pipe, the guide groove 2 is arranged in a horizontal direction; when the sodium fire suppression type outer casing is installed on a vertical pipe, the guide groove 2 is arranged in a vertical direction.

[0054] In one embodiment, the diversion trough 2 is formed by bending a portion of the housing through machining, or the diversion trough 2 and the housing are welded together in a prefabrication workshop. The diversion trough 2 has a hole to guide the sodium in the event of a sodium leakage. The drainage pipe 3 is welded to the diversion trough 2 to direct the leaked sodium into the sodium receiving tray and storage tank.

[0055] The branch pipe seat 9 is connected to the housing by welding, and the housing has a hole at the connection. The branch pipe seat 9 is set according to the pipeline process requirements to realize the cable extraction of electric heating, sodium leak detection, thermocouple, and sodium aerosol detection instruments. The branch pipe seat has a threaded hole inside, and the extraction cable is equipped with a threaded connector and sealing ring, which is sealed by tightening the threads.

[0056] In one embodiment, the support block 6 and the inner side of the shell are connected by welding in a prefabrication workshop. According to the stress conditions of the pipeline, an appropriate length of the support block is selected to support the outer sleeve.

[0057] In one embodiment, the quick locking device is welded to the outer surface of the housing in a prefabrication workshop.

[0058] In addition, based on the above-mentioned sodium fire suppression outer sleeve, an embodiment of the present application provides an installation method of the sodium fire suppression outer sleeve. The sodium fire suppression outer sleeve adopts a modular installation method, including:

[0059] In the prefabrication workshop, a portion of the lower half shell 1 is bent by machining to form the guide groove 2, or the guide groove 2 and the half shell 1 produced separately are welded together in the prefabrication workshop;

[0060] Connect the drainage pipe 3 to the bottom of the guide groove 2, for example, by welding;

[0061] Installing a plurality of support blocks 6 on the inner wall of the housing, for example, by welding;

[0062] The branch pipe seat 9 is mounted on the outer wall of the housing, for example, by welding;

[0063] According to the pipe network layout, select a number of sodium fire suppression outer sleeves, install the sodium fire suppression outer sleeves on the inner pipe, lay out the cables, and arrange the cables between the inner pipe and the sodium fire suppression outer sleeves. The cables are arranged through the branch pipe seat 9.

[0064] The two half shells 1 are overlapped by matching steps, and a sealing strip 5 is installed at the connection between the two half shells 1. The two half shells 1 are combined into a cylinder by the locking ring to the quick locking assembly 4 and pressure is applied to the sealing strip 5 to achieve sealing;

[0065] The two sodium fire suppression type outer sleeves are overlapped by matching steps, and a sealing ring 7 is installed at the overlap. The two sodium fire suppression type outer sleeves are connected by locking the axial quick locking assembly 8 and applying pressure to the sealing ring 7 to achieve sealing; the axial quick locking assemblies 8 of the two adjacent sodium fire suppression type outer sleeves are used in conjunction to connect the two sodium fire suppression type outer sleeves together in the axial direction;

[0066] Several sodium fire suppression outer sleeves are installed on the inner pipe. When sodium leakage occurs in the inner pipe, the sodium fire suppression outer sleeves collect and divert the leakage to deal with the sodium leakage.

[0067] The above description is only a specific implementation method of the present application, but the scope of protection of the present application is not limited thereto. Any changes or replacements that can be easily thought of by any technician familiar with this technical field within the technical scope disclosed in this application should be covered by the scope of protection of the present application.

Claims

1. A sodium fire suppression outer sleeve, characterized in that: The invention comprises a shell formed by splicing two half shells (1), wherein a support block (6) is installed on the inner wall of the shell, a guide groove (2) is installed on the half shell (1), and a drainage pipe (3) is connected to the guide groove (2) to drain out leaked sodium; a sealing strip (5) is provided at the connection between the two half shells (1) to achieve an annular seal; and a sealing ring (7) is provided between the two sodium fire suppression type outer sleeves to achieve axial sealing.

2. The sodium fire suppression outer sleeve according to claim 1, characterized in that: A branch pipe seat (9) is installed on the outer wall of the shell, and a hole is opened at the connection between the shell and the branch pipe seat (9), and the cable is led out from the branch pipe seat (9).

3. The sodium fire suppression outer sleeve according to claim 1, characterized in that: The connection between the two half shells (1) is an adaptive step structure, and the sealing strip (5) is installed on the step structure.

4. The sodium fire suppression outer sleeve according to claim 1, characterized in that: The connection between the two sodium fire suppression type outer sleeves is an adaptive step structure, and the sealing ring (7) is installed on the step structure.

5. The sodium fire suppression outer sleeve according to claim 1, characterized in that: The two half shells (1) are circumferentially locked by a locking ring quick locking assembly (4) and pressure is applied to the sealing strip (5) to achieve circumferential sealing.

6. The sodium fire suppression outer sleeve according to claim 1, characterized in that: The two sodium fire suppression type outer sleeves are axially locked by locking the axial quick locking assembly (8) and pressure is applied to the sealing ring (7) to achieve axial sealing.

7. The sodium fire suppression outer sleeve according to claim 1, characterized in that: The half shell (1) is a semi-cylindrical shell structure.

8. The sodium fire suppression outer sleeve according to claim 1, characterized in that: The support blocks (6) are evenly arranged along the circumferential direction.

9. The sodium fire suppression outer sleeve according to claim 1, characterized in that: The guide groove (2) and the half shell (1) are integrally formed or welded together.

10. A method for installing a sodium fire suppression outer sleeve according to any one of claims 1 to 9, characterized in that: Adopt modular installation, including: Bending a portion of the half shell (1) to form a guide groove (2), or welding the separately produced guide groove (2) to connect the half shell (1); Connecting the drainage pipe (3) below the guide groove (2); installing a plurality of support blocks (6) on the inner wall of the shell; According to the layout of the pipe network, a number of the sodium fire suppression outer sleeves are selected, the sodium fire suppression outer sleeves are installed on the process pipes, and the pipes are laid out; Installing a sealing strip (5), circumferentially locking the two half-shells (1) and applying pressure to the sealing strip (5) to achieve circumferential sealing; Installing a sealing ring (7), axially locking the two sodium fire suppression type outer sleeves and applying pressure to the sealing ring (7) to achieve axial sealing; A plurality of sodium fire suppression type outer sleeves are installed outside the process pipeline. When sodium leakage occurs in the process pipeline, the leaked sodium is discharged through the guide groove (2) and the drainage pipe (3).

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