Sealing ring for heat exchanger of nuclear power station and preparation method of sealing ring

Abstract

The invention relates to a sealing ring for a heat exchanger of a nuclear power station and a preparation method of the sealing ring. The sealing ring comprises a sealing ring body and ribs welded to the inner side face of the sealing ring body. Each of the sealing ring main body and the ribs independently comprises an inner layer, a middle layer and an outer layer from inside to outside; the inner layer comprises a spring; the middle layer comprises a nickel alloy layer; and the outer layer comprises a pure nickel layer. The sealing ring provided by the invention has good rebound resilience, and can ensure no leakage and avoid the use of silver-containing materials under the working condition of exceeding design pressure.

Description

Technical Field

[0001] The invention relates to the technical field of heat exchanger sealing of a pressurized water reactor nuclear power plant, and in particular to a sealing ring for a heat exchanger of a nuclear power plant and a preparation method thereof. Background Art

[0002] There are many nuclear-grade heat exchangers in nuclear power plants, which have the characteristics of high heat exchange efficiency and high sealing requirements. Especially for the third-generation nuclear power plants, super-baseline design conditions are proposed. At this time, the heat exchanger gasket can still ensure no leakage under the condition of super-design pressure (15.5MPa). In the above background, the heat exchanger gasket used in nuclear power plants is required to have the following characteristics: (1) with a spacer (rib) structure, which can effectively block the internal leakage between different tubes of the heat exchanger; (2) with high rebound, so that the heat exchanger will not be damaged under high tightening force, and the gasket can achieve sealing under the pressure of super-design conditions; (3) the material used can be accepted by the nuclear power plant.

[0003] At present, the gaskets used in nuclear power plant heat exchangers are divided into two categories. The first category is conventional metal spiral wound gaskets, which have a long application history and sufficient application experience. However, this type of gasket is based on design conditions. When the over-design conditions appear, the gasket cannot maintain effective rebound and leakage failure occurs. That is, the rebound amount of conventional metal spiral wound gaskets cannot meet the requirements of the over-design pressure conditions of the third-generation nuclear power. The second category is the silver ring gasket represented by the tube gasket of the third-generation nuclear power waste heat discharge heat exchanger. The outer layer of the gasket adopts a silver-containing structure, which uses the softness of the silver material to improve the sealing performance of the gasket.

[0004] However, when silver enters the primary circuit of a nuclear power plant, it will be activated into the radioactive isotope Ag-110m under neutron irradiation, which will have an adverse impact on the nuclear power plant in terms of overhaul period, collective dose, treatment of radioactive liquid waste and the amount of radioactive solid waste generated. Specifically, due to the long purification time of silver materials, the gasket will cause the overhaul time of the nuclear power plant to be prolonged, reducing economic benefits; due to the high activity-dose conversion coefficient ratio of Ag-110m, when silver is introduced into the primary circuit system of a nuclear power plant, Ag-110m has a greater impact on the radiation dose; due to the complex morphology of Ag-110m, the treatment of radioactive wastewater containing Ag-110m is difficult and the treatment cycle is long, which also causes an increase in the amount of radioactive solid waste generated.

[0005] Therefore, it is a technical problem that needs to be solved in the current field to provide a device that can meet the design requirements of the tube side gasket of the third-generation nuclear power waste heat removal heat exchanger, can still ensure no leakage under the condition of exceeding the design pressure (15.5MPa), and does not use sealing rings containing silver materials. Summary of the invention

[0006] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a sealing ring for a nuclear power plant heat exchanger and a preparation method thereof. Compared with the prior art, the sealing ring provided by the present invention has good resilience performance, can ensure no leakage under the condition of exceeding the design pressure (15.5MPa) and avoid the use of silver-containing materials.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a sealing ring for a heat exchanger in a nuclear power plant, the sealing ring comprising a sealing ring body and ribs welded to the inner side surface of the sealing ring body;

[0009] The sealing ring body and the ribs independently include an inner layer, a middle layer and an outer layer from the inside to the outside;

[0010] The inner layer includes a spring;

[0011] The intermediate layer comprises a nickel alloy layer;

[0012] The outer layer comprises a pure nickel layer.

[0013] In the sealing ring provided by the present invention, by adopting a laminated structure of a spring, a nickel alloy layer and a pure nickel layer, compared with a sealing ring with Ag as the outer layer, it is possible to achieve good resilience and sealing performance while avoiding the generation of radioactive isotope Ag-110m, thereby reducing the difficulty and cost of handling radioactive substances. In particular, the pure nickel layer used in the present invention has a good elastic modulus compared to ordinary nickel metal, thereby improving its resilience, and has good hardness, so it can meet the use requirements of the third-generation nuclear power waste heat removal heat exchanger under the condition of super design pressure (15.5MPa).

[0014] In the present invention, the material of the spring can be any common material for springs used for sealing rings in the art, for example, it can be Inconel x750.

[0015] In the present invention, the shape of the ribs is generally a hollow column, and the pure nickel layer at at least one end thereof is welded to the pure nickel layer on the inner side of the sealing ring body. The arrangement thereof can be adjusted accordingly according to the partition structure inside the heat exchanger. For example, it can be set to: the ribs are distributed radially along the center of the ring. There is no specific limit on the number of ribs, which can be selected according to the needs of the heat exchanger.

[0016] Preferably, in the sealing ring body, the inner layer spring is an annular structure; the nickel alloy layer is a hollow annular structure coated on the outside of the spring, and the inner surface of the nickel alloy layer is in close contact with the outer surface of the spring; the pure nickel layer is a hollow annular structure coated on the outside of the nickel alloy layer, and the inner surface of the pure nickel layer is in close contact with the outer surface of the nickel alloy layer.

[0017] Preferably, in the ribs, the inner layer of the spring is a columnar structure; the nickel alloy layer is a hollow columnar structure coated on the outside of the spring, and the inner surface of the nickel alloy layer is in close contact with the outer surface of the spring; the pure nickel layer is a hollow columnar structure coated on the outside of the nickel alloy layer, and the inner surface of the pure nickel layer is in close contact with the outer surface of the nickel alloy layer.

[0018] Preferably, in the sealing ring body and the ribs, the cross-sections of the intermediate layers are both C-shaped.

[0019] Preferably, in the sealing ring body, the cross-section of the outer layer is C-shaped.

[0020] Preferably, in the ribs, the cross-section of the outer layer is O-shaped.

[0021] In the present invention, the cross-section of the outer layer and the middle layer of the sealing ring body refers to the cross-section obtained by cutting the sealing ring body along the radial direction passing through the annular center; the cross-section of the rib refers to the cross-section obtained by cutting along the direction perpendicular to the axial direction of the rib.

[0022] Preferably, the nickel alloy contained in the nickel alloy layer includes any one of Inconel 600, Inconel 690 or Inconel 718, or a combination of at least two of them.

[0023] Preferably, the grade of pure nickel in the pure nickel layer is N6, and the implementation standard is GB5235-2021.

[0024] Preferably, the hardness of the pure nickel layer is 40-60HRB, for example, 40HRB, 42HRB, 45HRB, 48HRB, 50HRB, 52HRB, 55HRB, 58HRB or 60HRB, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0025] In a second aspect, the present invention provides a method for preparing a sealing ring for a heat exchanger in a nuclear power plant as described in the first aspect of the present invention, the preparation method comprising the following steps:

[0026] (1) a nickel alloy plate is made into a hollow annular structure with a C-shaped cross section, the interior of the hollow annular structure is filled with a matching annular spring, and then a pure nickel plate that has been annealed is coated on the outside of the hollow annular structure so that the cross section of the pure nickel plate is C-shaped, thereby obtaining a sealing ring body;

[0027] (2) forming a nickel alloy plate into a hollow columnar structure with a C-shaped cross section, filling the interior of the hollow columnar structure with a matching columnar spring, and then coating the outer side of the hollow columnar structure with an annealed pure nickel plate so that the cross section of the pure nickel plate is O-shaped, thereby obtaining a rib;

[0028] (3) performing helium shielded welding between the sealing ring body obtained in step (1) and the pure nickel layer of the rib obtained in step (2) to obtain a sealing ring;

[0029] There is no order relationship between step (1) and step (2).

[0030] In the preparation method provided by the present invention, on the one hand, by annealing the pure nickel plate, the pure nickel plate can have a certain hardness and improve its elastic modulus, thereby achieving good resilience performance and meeting the use requirements of the third-generation nuclear power waste heat removal heat exchanger under super design pressure (15.5MPa) conditions; on the other hand, by adopting helium shielded welding to weld the pure nickel layer of the sealing ring body and the ribs, the stability of the sealing ring structure can be further improved, thereby improving its structural stability and sealing under super design pressure conditions.

[0031] In the present invention, the nickel alloy plate is made into a hollow annular structure with a C-shaped cross section, and the method used is a conventional method in the art. Generally, the nickel alloy plate is first curled into a column with a C-shaped cross section, and then the two ends are relatively curled into an annular shape, and the interface is welded; the annular spring can also be made by a conventional method in the art, for example, the two ends of the spring are relatively curled into an annular shape, and the interface is welded; when the pure nickel plate is coated on the outside of the hollow annular structure, the annular interface also needs to be welded. The above-mentioned method for welding the interface of the nickel alloy plate, spring and pure nickel plate can be, for example, helium shielded welding, which is carried out under the conditions of a current of 70-85A and a voltage of 10-12V.

[0032] In the present invention, the thickness of the pure nickel plate is selected according to the needs, for example, a pure nickel plate of 0.3 mm ± 0.02 mm is generally selected.

[0033] Preferably, the temperature of the annealing treatment in step (1) and step (2) is independently 885-915°C, for example, it can be 885°C, 886°C, 887°C, 888°C, 890°C, 892°C, 894°C, 896°C, 898°C, 900°C, 902°C, 904°C, 906°C, 908°C, 910°C, 912°C, 914°C or 915°C, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0034] In the present invention, by preferably controlling the annealing temperature within a specific range, the hardness of pure nickel can be reduced, specifically, the hardness of the pure nickel plate with the grade N6 can be reduced from 80-100 HRB without annealing to 40-60 HRB.

[0035] Preferably, the annealing time in step (1) and step (2) is independently 4-6 min, for example, 4 min, 4.2 min, 4.4 min, 4.6 min, 4.8 min, 5 min, 5.2 min, 5.4 min, 5.6 min, 5.5 min or 6 min, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0036] Preferably, the welding current of the helium shielded welding in step (3) is 70-85A, for example, it can be 70A, 72A, 75A, 76A, 78A, 80A, 82A or 85A, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0037] In the present invention, by preferably controlling the welding current of helium shielded welding within a specific range, problems such as incomplete penetration and loose welding caused by too small current can be avoided, and problems such as overheating of the material and burn-through caused by too large current can be avoided.

[0038] Preferably, the welding voltage of the helium shielded welding is 10-12V, for example, 10V, 10.5V, 11V, 11.5V or 12V, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0039] In the present invention, by preferably controlling the welding voltage of helium shielded welding within a specific range, welding defects caused by excessively high or low voltage can be avoided.

[0040] Preferably, the diameter of the welding wire for helium shielded welding in step (3) is ≤0.8 mm, for example, it can be 0.8 mm, 0.7 mm, 0.6 mm or 0.5 mm, but is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0041] In the present invention, the material of the welding wire is pure nickel, which is generally the same as the material of the pure nickel layer.

[0042] As a preferred technical solution of the second aspect of the present invention, the preparation method comprises the following steps:

[0043] (1) a nickel alloy plate is made into a hollow annular structure with a C-shaped cross section, the interior of the hollow annular structure is filled with a matching annular spring, and then a pure nickel plate that has been annealed is coated on the outside of the hollow annular structure so that the cross section of the pure nickel plate is C-shaped, thereby obtaining a sealing ring body;

[0044] (2) forming a nickel alloy plate into a hollow columnar structure with a C-shaped cross section, filling the interior of the hollow columnar structure with a matching columnar spring, and then coating the outer side of the hollow columnar structure with an annealed pure nickel plate so that the cross section of the pure nickel plate is O-shaped, thereby obtaining a rib;

[0045] The annealing temperatures in step (1) and step (2) are independently 885-915° C., and the annealing times are independently 4-6 min.

[0046] (3) Helium shielded welding is performed between the sealing ring body obtained in step (1) and the pure nickel layer of the rib obtained in step (2), wherein the helium shielded welding uses a welding wire with a diameter of ≤0.8 mm, and is performed under the conditions of a welding current of 70-85 A and a welding voltage of 10-12 V to obtain a sealing ring.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] The sealing ring for a nuclear power plant provided by the present invention has excellent resilience and effective rebound capacity. Compared with the resilience of common sealing rings such as graphite spiral wound gaskets, which can only reach 0.25 mm or more, the resilience of the sealing ring provided by the present invention can reach 0.46 mm or more, and the effective rebound capacity under 0.1 MPa can reach 0.25 mm or more, specifically 0.257 mm, and the helium leakage rate under 0.1 MPa is less than 1.0×10 -7 Pa·m 3 / s; the effective rebound amount under overpressure conditions (15.5MPa) can reach more than 0.16mm, specifically 17mm, and there is no leakage in the water pressure test, which meets the design requirements of the third-generation nuclear power plant for heat exchanger gaskets under conditions of over-design pressure. Under conditions of over-design pressure (15.5MPa), there is still no leakage, and there is no need to use silver-containing materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 is a schematic diagram of the top view of the sealing ring described in Example 1 of the present invention;

[0050] Figure 2 is a schematic diagram of the cross-sectional structure of the sealing ring body described in Example 1 of the present invention;

[0051] Figure 3 is a schematic diagram of the cross-sectional structure of the rib described in Example 1 of the present invention;

[0052] Among them, 1-sealing ring body; 2-rib; 3-spring; 4-nickel alloy layer; 5-pure nickel layer. DETAILED DESCRIPTION

[0053] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0054] In the following embodiments and comparative examples, a nickel alloy plate is curled into a column with a C-shaped cross-section, and then the two ends are curled into a ring shape, and the interfaces are welded to obtain a hollow ring structure; the two ends of the Inconel x750 spring are curled into a ring shape, and the interfaces are welded to obtain a ring spring. When a pure nickel plate is coated on the outside of the hollow ring structure, the annular interface is welded. The welding methods at the above interfaces all adopt helium shielded welding, and are carried out under the conditions of a current of 80A and a voltage of 11V.

[0055] Example 1

[0056] This embodiment provides a sealing ring for a heat exchanger in a nuclear power plant. The top view of the sealing ring is shown in FIG. Figure 1 As shown, the sealing ring comprises a sealing ring body 1 and ribs 2 welded to the inner side of the sealing ring body 1, the number of the ribs 2 is 3, all of which are distributed along the radial direction through the center of the ring, wherein the angles between two adjacent ribs are 90°, 90° and 180° respectively, and the sealing ring body 1 and the ribs 2 independently comprise an inner layer, a middle layer and an outer layer from the inside to the outside;

[0057] In the sealing ring body 1, Figure 1 and Figure 2 As shown, the inner layer is a spring 3 and is an annular structure; the middle layer is a nickel alloy layer 4 and is a hollow annular structure coated on the outside of the spring 3, with a C-shaped cross section, and the inner surface of the nickel alloy layer 4 is in close contact with the outer surface of the spring 3; the outer layer is a pure nickel layer 5 and is a hollow annular structure coated on the outside of the nickel alloy layer 4, with a C-shaped cross section, and the inner surface of the pure nickel layer 5 is in close contact with the outer surface of the nickel alloy layer 4;

[0058] In the rib 2, Figure 1 and Figure 3 As shown, the inner layer is a spring 3 and is a columnar structure; the middle layer is a nickel alloy layer 4 and is a hollow columnar structure coated on the outside of the spring 3, with a C-shaped cross section, and the inner surface of the nickel alloy layer 4 is in close contact with the outer surface of the spring 3; the outer layer is a pure nickel layer 5 and is a hollow columnar structure coated on the outside of the nickel alloy layer 4, with an O-shaped cross section, and the inner surface of the pure nickel layer 5 is in close contact with the outer surface of the nickel alloy layer 4;

[0059] The pure nickel layer 5 at the end of the rib 2 near the sealing ring body 1 is welded to the pure nickel layer 5 on the inner side of the sealing ring body 1;

[0060] In this embodiment, the material of the nickel alloy layer 4 is Inconel 600, the grade of pure nickel is N6, and the hardness of the pure nickel layer 5 is 50HRB.

[0061] This embodiment also provides a method for preparing the sealing ring for the heat exchanger of a nuclear power plant, the preparation method comprising the following steps:

[0062] (1) a nickel alloy plate is made into a hollow annular structure with a C-shaped cross section, the interior of the hollow annular structure is filled with a matching annular spring 3, and then a pure nickel plate after annealing is coated on the outside of the hollow annular structure so that the cross section of the pure nickel plate is C-shaped, thereby obtaining a sealing ring body 1;

[0063] (2) a nickel alloy plate is made into a hollow columnar structure with a C-shaped cross section, the interior of the hollow columnar structure is filled with a matching columnar spring 3, and then a pure nickel plate after annealing is coated on the outside of the hollow columnar structure and the cross section of the pure nickel plate is made into an O-shaped shape, thereby obtaining a rib 2;

[0064] The annealing temperatures in step (1) and step (2) are each independently 900° C., and the annealing times are each independently 5 min.

[0065] (3) Helium shielded welding is performed between the sealing ring body 1 obtained in step (1) and the pure nickel layer 5 of the rib 2 obtained in step (2). The helium shielded welding uses a welding wire with a diameter of 0.8 mm and is performed under the conditions of a welding current of 80 A and a welding voltage of 11 V to obtain a sealing ring.

[0066] Example 2

[0067] This embodiment provides a sealing ring for a heat exchanger in a nuclear power plant. The only difference compared with Embodiment 1 is that the material of the nickel alloy layer is Inconel 690, the grade of pure nickel is N6, and the hardness of the pure nickel layer is 45HRB.

[0068] This embodiment also provides a method for preparing the sealing ring for the heat exchanger of a nuclear power plant, the preparation method comprising the following steps:

[0069] (1) a nickel alloy plate is made into a hollow annular structure with a C-shaped cross section, the interior of the hollow annular structure is filled with a matching annular spring, and then a pure nickel plate that has been annealed is coated on the outside of the hollow annular structure so that the cross section of the pure nickel plate is C-shaped, thereby obtaining a sealing ring body;

[0070] (2) forming a nickel alloy plate into a hollow columnar structure with a C-shaped cross section, filling the interior of the hollow columnar structure with a matching columnar spring, and then coating the outer side of the hollow columnar structure with an annealed pure nickel plate so that the cross section of the pure nickel plate is O-shaped, thereby obtaining a rib;

[0071] The annealing temperatures in step (1) and step (2) are each independently 885° C., and the annealing times are each independently 6 min.

[0072] (3) Helium shielded welding is performed between the sealing ring body obtained in step (1) and the pure nickel layer of the rib obtained in step (2), wherein the helium shielded welding uses a welding wire with a diameter of 0.8 mm, and is performed under the conditions of a welding current of 70 A and a welding voltage of 12 V to obtain a sealing ring.

[0073] Example 3

[0074] This embodiment provides a sealing ring for a heat exchanger in a nuclear power plant. The only difference compared with Embodiment 1 is that the material of the nickel alloy layer is Inconel 718, the grade of pure nickel is N6, and the hardness of the pure nickel layer is 55HRB.

[0075] This embodiment also provides a method for preparing the sealing ring for the heat exchanger of a nuclear power plant, the preparation method comprising the following steps:

[0076] (1) a nickel alloy plate is made into a hollow annular structure with a C-shaped cross section, the interior of the hollow annular structure is filled with a matching annular spring, and then a pure nickel plate that has been annealed is coated on the outside of the hollow annular structure so that the cross section of the pure nickel plate is C-shaped, thereby obtaining a sealing ring body;

[0077] (2) forming a nickel alloy plate into a hollow columnar structure with a C-shaped cross section, filling the interior of the hollow columnar structure with a matching columnar spring, and then coating the outer side of the hollow columnar structure with an annealed pure nickel plate so that the cross section of the pure nickel plate is O-shaped, thereby obtaining a rib;

[0078] The annealing temperatures in step (1) and step (2) are each independently 915° C., and the annealing times are each independently 4 min.

[0079] (3) Helium shielded welding is performed between the sealing ring body obtained in step (1) and the pure nickel layer of the rib obtained in step (2), wherein the helium shielded welding uses a welding wire with a diameter of 0.8 mm, and is performed under the conditions of a welding current of 85 A and a welding voltage of 10 V to obtain a sealing ring.

[0080] Comparative Example 1

[0081] This comparative example provides a sealing ring for a nuclear power plant heat exchanger, which is different from Example 1 only in that the pure nickel plate is not annealed in step (1) and step (2).

[0082] The effective rebound of the sealing rings prepared in Examples 1-9 and Comparative Example 1 at 0.1 MPa and 15.5 MPa was tested by a water pressure test (flange separation test), and the results are shown in Table 1; the helium leakage rate was tested at 0.1 MPa, and the results are shown in Table 1.

[0083] In the present invention, the rebound performance refers to the ability of the sealing ring to recover to its original shape after compression, which is generally expressed in mm. The effective rebound amount refers to the rebound amount of the sealing ring without leakage under a certain pressure. As shown in Table 1, the effective rebound amounts of the sealing ring are tested at 0.1 MPa and 15.5 MPa, respectively.

[0084] Table 1

[0085]

[0086]

[0087] From the comparison between Example 1 and Comparative Example 1, it can be seen that the only difference between Comparative Example 1 and Example 1 is that the pure nickel plates are not annealed. The results of the water pressure test show that in Example 1, the effective rebound amount at 15.5 MPa reaches 0.17 mm and there is no leakage in the water pressure test at this time, while the effective rebound amount at 15.5 MPa in Comparative Example 1 can only reach 0.13 mm and leakage occurs at this time. It can be seen that the present invention can make the pure nickel plate have a certain hardness and improve its elastic modulus by annealing the pure nickel plate, thereby achieving good rebound performance, meeting the use requirements of the third-generation nuclear power waste heat removal heat exchanger under super design pressure (15.5 MPa) conditions, and avoiding the use of silver-containing materials.

[0088] In summary, the sealing ring provided by the present invention has good resilience performance, can ensure no leakage under the condition of super design pressure and avoid the use of silver-containing materials.

[0089] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A sealing ring for a heat exchanger in a nuclear power plant, characterized in that: The sealing ring comprises a sealing ring body and ribs welded to the inner side of the sealing ring body; The sealing ring body and the ribs independently include an inner layer, a middle layer and an outer layer from the inside to the outside; The inner layer includes a spring; The intermediate layer comprises a nickel alloy layer; The outer layer comprises a pure nickel layer.

2. The sealing ring according to claim 1, characterized in that: In the sealing ring body, the inner spring is a ring structure; The nickel alloy layer is a hollow ring structure covering the outside of the spring, and the inner surface of the nickel alloy layer is in close contact with the outer surface of the spring; The pure nickel layer is a hollow annular structure coated on the outside of the nickel alloy layer, and the inner surface of the pure nickel layer is in close contact with the outer surface of the nickel alloy layer.

3. The sealing ring according to claim 1 or 2, characterized in that: In the ribs, the inner layer of springs is a columnar structure; The nickel alloy layer is a hollow columnar structure covering the outside of the spring, and the inner surface of the nickel alloy layer is in close contact with the outer surface of the spring; The pure nickel layer is a hollow columnar structure coated on the outside of the nickel alloy layer, and the inner surface of the pure nickel layer is in close contact with the outer surface of the nickel alloy layer.

4. The sealing ring according to any one of claims 1 to 3, characterized in that: In the sealing ring body and the ribs, the cross-section of the middle layer is C-shaped; Preferably, in the sealing ring body, the cross section of the outer layer is C-shaped; Preferably, in the ribs, the cross-section of the outer layer is O-shaped.

5. The sealing ring according to any one of claims 1 to 4, characterized in that: The nickel alloy contained in the nickel alloy layer includes any one of Inconel 600, Inconel 690 or Inconel 718 or a combination of at least two thereof; Preferably, the grade of pure nickel in the pure nickel layer is N6, and the implementation standard is GB5235-2021; Preferably, the hardness of the pure nickel layer is 40-60 HRB.

6. A method for preparing a sealing ring for a heat exchanger in a nuclear power plant according to any one of claims 1 to 5, characterized in that: The preparation method comprises the following steps: (1) a nickel alloy plate is made into a hollow annular structure with a C-shaped cross section, the interior of the hollow annular structure is filled with a matching annular spring, and then a pure nickel plate that has been annealed is coated on the outside of the hollow annular structure so that the cross section of the pure nickel plate is C-shaped, thereby obtaining a sealing ring body; (2) forming a nickel alloy plate into a hollow columnar structure with a C-shaped cross section, filling the interior of the hollow columnar structure with a matching columnar spring, and then coating the outer side of the hollow columnar structure with an annealed pure nickel plate so that the cross section of the pure nickel plate is O-shaped, thereby obtaining a rib; (3) performing helium shielded welding between the sealing ring body obtained in step (1) and the pure nickel layer of the rib obtained in step (2) to obtain a sealing ring; There is no order relationship between step (1) and step (2).

7. The preparation method according to claim 6, characterized in that: The annealing temperatures in step (1) and step (2) are independently 885-915° C.; Preferably, the annealing treatment time in step (1) and step (2) is independently 4-6 minutes.

8. The preparation method according to claim 6 or 7, characterized in that: The welding current of the helium shielded welding in step (3) is 70-85A; Preferably, the welding voltage of the helium shielded welding is 10-12V.

9. The preparation method according to any one of claims 6 to 8, characterized in that: The diameter of the welding wire for helium shielded welding in step (3) is ≤0.8 mm.

10. The preparation method according to any one of claims 6 to 9, characterized in that: The preparation method comprises the following steps: (1) a nickel alloy plate is made into a hollow annular structure with a C-shaped cross section, the interior of the hollow annular structure is filled with a matching annular spring, and then a pure nickel plate that has been annealed is coated on the outside of the hollow annular structure so that the cross section of the pure nickel plate is C-shaped, thereby obtaining a sealing ring body; (2) forming a nickel alloy plate into a hollow columnar structure with a C-shaped cross section, filling the interior of the hollow columnar structure with a matching columnar spring, and then coating the outer side of the hollow columnar structure with an annealed pure nickel plate so that the cross section of the pure nickel plate is O-shaped, thereby obtaining a rib; The annealing temperatures in step (1) and step (2) are independently 885-915° C., and the annealing times are independently 4-6 min. (3) Helium shielded welding is performed between the sealing ring body obtained in step (1) and the pure nickel layer of the rib obtained in step (2), wherein the helium shielded welding uses a welding wire with a diameter of ≤0.8 mm, and is performed under the conditions of a welding current of 70-85 A and a welding voltage of 10-12 V to obtain a sealing ring.

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