Nuclear power station spontaneous heating cladding tube corrosion product deposition sample piece

Abstract

The utility model provides a nuclear power station spontaneous heating cladding tube corrosion product deposition sample piece. The sample piece comprises a cladding tube; the sealing plug is arranged at the first end of the cladding tube; the heating elements are arranged in the cladding tube through the second end of the cladding tube, and insulating fillers are arranged between the heating elements and between the heating elements and the cladding tube; the roughness of the outer circumferential surface of the cladding tube reaches the standard required by the nuclear power station; the method has the beneficial effects that the cladding tube, the sealing plug, the heating element and the insulating filler are assembled to form the sample piece, and the roughness of the outer surface of the cladding tube reaches the surface roughness standard required by the nuclear power station through polishing treatment; the device can be effectively applied to a fuel cladding surface corrosion product deposition test to simulate the surface thermal characteristics of a cladding tube in a reactor, the test is more accurate, the corrosion product deposition mechanism and rule on the cladding surface can be known, and a basis is provided for evaluating the fuel cladding scale deposition risk.

Description

Technical Field

[0001] This application belongs to the technical field of corrosion product deposition tests, and particularly relates to a corrosion product deposition sample of a self-heating cladding tube in a nuclear power plant. Background Art

[0002] The operation experience of existing nuclear power plants shows that key components mainly represented by steam generator heat transfer tubes and main pipelines will corrode during service and continuously release corrosion products to the coolant. These corrosion products migrate with the circulation system and tend to deposit on the surface of the core fuel cladding to form scale, causing a series of adverse effects on the operation of the reactor. Conducting research on the corrosion product deposition test of corrosion products on the fuel cladding surface is conducive to understanding the corrosion product deposition mechanism and law on the cladding surface, and providing a basis for evaluating the scale risk of the fuel cladding.

[0003] The in-core cladding tube is in an environment where the fuel inside the tube generates heat and the high-flow cooling water outside the tube cools it. In the research on the corrosion product deposition test of the fuel cladding, it is necessary to simulate the self-heating characteristics of the cladding tube so that the surface thermal state of the cladding tube during the test can be restored as much as possible to its thermal state in the reactor. However, the existing research on corrosion product deposition tests has focused on the deposition behavior of corrosion products on steam generator heat transfer tubes, mainly using non-self-heating pipes in the test loop as corrosion product deposition samples to study the deposition phenomenon of corrosion products on the loop pipes. This method is not applicable to the research on the corrosion product deposition test of the fuel cladding surface. Therefore, to ensure the accuracy and practicality of the research on the corrosion product deposition test of the fuel cladding surface, it is urgent to develop a corrosion product deposition sample of a self-heating cladding tube in a nuclear power plant for the corrosion product deposition research and engineering evaluation of the nuclear power plant fuel cladding. Utility Model Content

[0004] This utility model aims to solve at least one of the technical problems existing in the prior art or related technologies.

[0005] To solve the above problems, this application provides a corrosion product deposition sample of a self-heating cladding tube in a nuclear power plant, which includes:

[0006] A cladding tube;

[0007] A sealing plug, which is arranged at the first end of the cladding tube;

[0008] A heating element, which is arranged inside the cladding tube through the second end of the cladding tube, and insulating fillers are arranged between the heating elements and between the heating elements and the cladding tube;

[0009] Wherein, the roughness of the outer circumferential surface of the cladding tube meets the standards required for nuclear power plants.

[0010] Optionally, the sealing plug includes:

[0011] A connecting section, which is arranged inside the cladding tube;

[0012] A fixing section, which is connected to the connecting section and is located outside the cladding tube.

[0013] Optionally, the outer diameter of the connecting section is the same as the inner diameter of the cladding tube, and the outer diameter of the fixing section is greater than the inner diameter of the cladding tube.

[0014] Optionally, the fixing section of the sealing plug is welded to the cladding tube.

[0015] Optionally, the sealing plug further includes:

[0016] A protruding section, which is arranged on the side of the fixing section away from the connecting section.

[0017] Optionally, the heating element is a resistance wire.

[0018] Optionally, the heating elements are evenly distributed inside the cladding tube.

[0019] Optionally, the insulating filler is a magnesium oxide insulating material.

[0020] Optionally, the material of the cladding tube is zirconium alloy.

[0021] Advantages

[0022] In the embodiment of the present utility model, a sample for depositing corrosion products of a self-heating cladding tube in a nuclear power plant has the following advantages: By assembling the cladding tube, the sealing plug, the heating element and the insulating filler to form a sample, and removing the deformed layer on the outer surface of the cladding tube by grinding, and polishing the outer surface of the cladding tube to reach the surface roughness standard required by the nuclear power plant, it can be effectively applied to simulate the surface thermal characteristics of the in-core cladding tube in the fuel cladding surface corrosion product deposition test, making the experiment more accurate, which is beneficial to understanding the corrosion product deposition mechanism and law on the cladding surface and providing a basis for evaluating the fouling risk of the fuel cladding. Description of the Drawings

[0023] Figure 1 It is the front view structure diagram of the present utility model;

[0024] Figure 2 It is the structure diagram of the sealing plug of the present utility model.

[0025] The reference numerals are shown as:

[0026] 1. Cladding tube; 2. Sealing plug; 21. Connecting section; 22. Fixing section; 23. Protruding section; 3. Heating element; 4. Insulating filler. Detailed implementation mode

[0027] In the description of the present application, it should be understood that the orientation or positional relationship indicated by the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present utility model and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present utility model.

[0028] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present utility model, "a plurality" means two or more unless otherwise specifically defined.

[0029] In the present application, unless otherwise clearly specified and defined, the terms "installed", "connected", "connected", "fixed", etc. should be understood in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances.

[0030] The following describes the preferred embodiments of the present utility model with reference to the drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present utility model and are not used to limit the present utility model.

[0031] Combined with Figure 1-2 As shown, according to an embodiment of the present application, a sample for depositing corrosion products of a self-heating cladding tube of a nuclear power plant is provided, which includes:

[0032] A cladding tube 1;

[0033] A sealing plug 2, which is arranged on the first end of the cladding tube 1;

[0034] A heating element 3, which is arranged inside the cladding tube 1 through the second end of the cladding tube 1, and an insulating filler 4 is arranged between the heating element 3 and the cladding tube 1;

[0035] Wherein, the roughness of the outer circumferential surface of the cladding tube 1 reaches the standard required for a nuclear power plant.

[0036] Specifically, the cladding tube 1 is a hollow thin-walled long tube with both ends open. The sealing plug 2 is installed at the first end of the cladding tube 1 to achieve the sealing of the first end and prevent the corrosive medium from entering the interior of the cladding tube 1 during the experiment; the heating element 3 and the insulating filler 4 are installed into the interior from the second end of the cladding tube 1. The insulating filler 4 completely wraps and separates the heating element 3. After the heating element 3 is energized, it generates heat to simulate the heat flux density generated by the nuclear fuel reaction on the cladding. The generated heat can be transmitted to the cladding tube 1 through the insulating filler 4 to restore the actual use scenario. The outer surface of the cladding tube 1 is the test section for corrosion product deposition test, which is used for the research of corrosion product deposition test. The deformed layer on the outer surface of the cladding tube 1 is removed by grinding, and the surface roughness of the outer surface of the cladding tube 1 reaches the surface roughness standard required by the nuclear power plant through polishing treatment, so that it can be effectively applied to the fuel cladding surface corrosion product deposition test to simulate the surface thermal characteristics of the in-core cladding tube 1, making the experiment more accurate, which is conducive to understanding the corrosion product deposition mechanism and law on the cladding surface and providing a basis for evaluating the fouling risk of the fuel cladding.

[0037] Among them, the insulating filler 4 is filled in the gap of the cladding tube 1 for insulation and heat transfer.

[0038] Among them, the cladding tube 1 is a hollow thin-walled long tube, and the tube diameter and other dimensions are the standard dimensions of the nuclear power plant, which can make the experiment closer to the actual use scenario and improve the accuracy of the experimental results.

[0039] The sealing plug 2 includes:

[0040] A connecting section 21, and the connecting section 21 is arranged inside the cladding tube 1;

[0041] A fixing section 22, the fixing section 22 is connected to the connecting section 21, and the fixing section 22 is located outside the cladding tube 1.

[0042] The outer diameter of the connecting section 21 is the same as the inner diameter of the cladding tube 1, and the outer diameter of the fixing section 22 is larger than the inner diameter of the cladding tube 1.

[0043] The fixing section 22 of the sealing plug 2 is welded to the cladding tube 1.

[0044] Specifically, the sealing plug 2 includes a connecting section 21 and a fixing section 22. Both the connecting section 21 and the fixing section 22 are cylindrical structures. The connecting section 21 is installed inside the cladding tube 1, and the fixing section 22 is connected to the connecting section 21 and is located outside the cladding tube 1. The fixing section 22 is welded to the first end of the cladding tube 1, and there is no gap between the first end of the cladding tube 1 and the fixing section 22, which can prevent the corrosive medium from entering the interior of the cladding tube 1 during the experiment and affecting the insulating filler 4 and the heating element 3, and improve the accuracy of the experimental results.

[0045] Among them, the fixed section 22 and the connecting section 21 can have the same diameter or different diameters. When the fixed section 22 and the connecting section 21 have the same diameter, the outer diameters of both the fixed section 22 and the connecting section 21 are the same as the inner diameter of the cladding tube 1, and the fixed section 22 is welded and sealed to the first end of the cladding tube 1 by welding; when the fixed section 22 and the connecting section 21 have different diameters, the diameter of the connecting section 21 is the same as the inner diameter of the cladding tube 1, the outer diameter of the fixed section 22 is greater than the inner diameter of the cladding tube 1, and the first end of the cladding tube 1 can be covered during the connection of the fixed section 22 and the connecting section 21. In this way, after welding the fixed section 22 and the cladding tube 1 by welding, the sealing performance is better.

[0046] Among them, the fixed section 22 and the cladding tube 1 are welded by vacuum electron beam welding. Welding in a vacuum environment can effectively avoid oxidation and contamination, thereby obtaining a pure and high-quality weld. The structure of the weld is fine, the mechanical properties are excellent, the heat input is concentrated during the welding process, the heat-affected zone is narrow, and the influence on the properties of the surrounding materials is small.

[0047] The sealing plug 2 further includes:

[0048] A convex section 23, and the convex section 23 is arranged on the side of the fixed section 22 away from the connecting section 21.

[0049] Specifically, the convex section 23 is installed on the side of the fixed section 22 away from the connecting section 21, and the convex section 23 is located outside the cladding tube 1. During processing, the sealing plug 2 can be taken by the convex section 23, improving the processing efficiency; at the same time, the sealing plug 2 can also be taken by the convex section 23 and installed on the cladding tube 1, facilitating subsequent welding and improving the stability of welding.

[0050] The heating element 3 is a resistance wire.

[0051] Specifically, the heating element 3 is a resistance wire made of tungsten material, and its resistance value changes relatively stably with temperature, which is beneficial to accurately control the temperature in occasions with high temperature control requirements.

[0052] Among them, the power of the sample cladding tube 1 is determined according to parameters such as the surface power density and surface temperature of the sample cladding tube 1. The material, size and quantity of the heating wire are determined by the power, and a resistance wire is made.

[0053] The heating element 3 is evenly distributed inside the cladding tube 1.

[0054] Specifically, by evenly distributing the heating element 3 inside the cladding tube 1, the heat flux density transferred to the cladding tube 1 is more uniform, improving the experimental accuracy.

[0055] The insulating filler 4 is a magnesium oxide insulating material.

[0056] Specifically, the insulating filler 4 is made of magnesium oxide insulating material. Magnesium oxide has an extremely high resistivity, which can effectively prevent the passage of electric current, ensure the safe operation of electrical equipment, and can maintain stable insulating performance in high-temperature environments, withstanding high temperatures without performance degradation.

[0057] The material of the cladding tube 1 is zirconium alloy.

[0058] Specifically, the material of the cladding tube 1 is zirconium alloy, which has excellent corrosion resistance to various acids (such as hydrochloric acid, nitric acid, sulfuric acid, and acetic acid), alkalis, and salts. Zirconium has a low thermal neutron absorption cross-section and good compatibility with nuclear fuel. It can be used as the core structure material of a water-cooled nuclear reactor, such as fuel cladding, pressure tubes, brackets, and channel tubes. Zirconium and zirconium alloys have good plasticity and can be made into products of different shapes such as tubes, plates, rods, and wires through various processing techniques.

[0059] A method for preparing a sample of corrosion product deposition on a self-heating cladding tube of a nuclear power plant includes the following steps:

[0060] Step 1, preparation of the cladding tube 1: Cut the standard cladding tube for nuclear power plants into appropriate lengths to serve as the cladding tube 1 of the sample. Use a zirconium alloy hollow tube as the cladding tube 1. The initial outer diameter of the cladding tube is about 11 mm, and the wall thickness is about 1 mm. Use a numerically controlled slow wire electrical discharge machine to cut a length of about 1 m along the length direction on the cladding tube 1 as the cladding tube 1 of the corrosion product deposition sample.

[0061] Step 2, preparation of the heating element 3: Determine the power of the sample according to the surface power density requirement of the sample cladding tube 1, etc., and prepare the heating element 3. Determine the power of the sample cladding tube 1 according to parameters such as the surface power density and surface temperature of the sample cladding tube 1, determine the material, size, and quantity of the heating wire through the power, and make a resistance wire.

[0062] Step 3, sample assembly: Place the heating element 3 and the insulating filler 4 inside the cladding tube 1 and compact them. After compaction, weld the cladding tube 1 to the sealing plug 2 to assemble the sample. Place the heating element 3 and the insulating filler 4 inside the cladding tube 1. The insulating filler 4 completely wraps and separates the heating element 3, and then compact the insulating material by cold drawing and other diameter-reducing methods for the cladding tube 1. After diameter reduction, the diameter of the cladding tube 1 is about 9.5 mm. After compaction, weld between the cladding tube 1 and the sealing plug 2 by vacuum electron beam welding to complete the sample assembly.

[0063] Step 4, sample polishing: Remove the deformed layer on the outer surface of the cladding tube 1 by grinding, and polish the outer surface of the cladding tube 1 to reach the surface roughness standard required for nuclear power plants.

[0064] Through the above steps, the design and preparation of the cladding tube 1 sample can be achieved, which has the advantages of simple process, low cost, etc. Using it for experiments is conducive to understanding the deposition mechanism and rules of corrosion products on the cladding surface, and providing a basis for evaluating the fouling risk of the fuel cladding.

[0065] The above are only the preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application. The above is only the preferred implementation manner of the present application. It should be noted that for those of ordinary skill in the art in this technical field, without departing from the technical principle of the present application, several improvements and modifications can still be made, and these improvements and modifications should also be regarded as the protection scope of the present application.

Claims

1. A self-heating cladding tube corrosion product deposition sample for a nuclear power plant, characterized in that, Comprising: A cladding tube (1); A sealing plug (2), which is arranged at the first end of the cladding tube (1); A heating element (3), which is arranged inside the cladding tube (1) through the second end of the cladding tube (1), and an insulating filler (4) is arranged between the heating elements (3) and between the heating element (3) and the cladding tube (1); Wherein, the roughness of the outer circumferential surface of the cladding tube (1) reaches the standard required for nuclear power plants.

2. The self-heating cladding tube corrosion product deposition sample for nuclear power plants according to claim 1, characterized in that The sealing plug (2) comprises: A connecting section (21), which is arranged inside the cladding tube (1); A fixing section (22), which is connected to the connecting section (21), and the fixing section (22) is located outside the cladding tube (1).

3. The self-heating cladding tube corrosion product deposition sample for nuclear power plants according to claim 2, characterized in that, The outer diameter of the connecting section (21) is the same as the inner diameter of the cladding tube (1), and the outer diameter of the fixing section (22) is larger than the inner diameter of the cladding tube (1).

4. The self-heating cladding tube corrosion product deposition sample for nuclear power plants according to claim 3, characterized in that The fixing section (22) of the sealing plug (2) is welded to the cladding tube (1).

5. The self-heating cladding tube corrosion product deposition sample for nuclear power plants according to claim 4, characterized in that, The sealing plug (2) further comprises: A convex section (23), which is arranged on the side of the fixing section (22) away from the connecting section (21).

6. The corrosion product deposition sample of the self-heating cladding tube of a nuclear power plant according to claim 1, wherein The heating element (3) is a resistance wire.

7. The sample of corrosion product deposition on the self-heating cladding tube of a nuclear power plant according to claim 1, characterized in that, The heating elements (3) are evenly distributed inside the cladding tube (1).

8. The sample of corrosion product deposition of the self-heating cladding tube of a nuclear power plant according to claim 1, characterized in that, The insulating filler (4) is a magnesium oxide insulating material.

9. The self-heating cladding tube corrosion product deposition sample for nuclear power plants according to claim 1, characterized in that, The material of the cladding tube (1) is zirconium alloy.

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