Method for detecting sodium in sodium-related pipeline

Abstract

The invention particularly relates to a method for detecting sodium in a sodium-related pipeline, which comprises the following steps of: 1, locally heating a single side of the sodium-related pipeline as a heating side of the sodium-related pipeline; taking the side opposite to the heating side of the sodium-related pipeline as a non-heating side of the sodium-related pipeline; 2, temperature measurement is carried out on the heating side and the non-heating side of the sodium-related pipeline at the same time; 3, judging whether sodium exists in the sodium-related pipeline or not according to the temperature difference between the heating side and the non-heating side of the sodium-related pipeline, and calculating the sodium content in the sodium-related pipeline; and the temperature difference when sodium exists in the sodium-related pipeline is smaller than the temperature difference when sodium does not exist in the sodium-related pipeline. According to the method for detecting the sodium in the sodium-related pipeline, whether the sodium exists in the sodium-related pipeline or not is simply and rapidly detected, and the maintenance operation safety of the sodium-related pipeline is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of sodium-cooled fast reactor nuclear power plant equipment detection, in particular to a method for detecting sodium in a sodium-related pipeline. Background Art

[0002] The main circuit of the demonstration fast reactor uses sodium as a coolant, and there are a large number of sodium-related pipelines. However, only the sodium-related pipelines in important locations are equipped with sodium presence detection instruments, and the vast majority of sodium-related pipelines are not equipped with sodium presence detection instruments. According to the physical properties of metallic sodium, its melting point is 97.8°C, and it is solid at room temperature. During the operation of the power plant, it is inevitable to cut or remove the pipeline during the maintenance of the sodium-related pipelines. Before cutting or removing the pipeline, it is necessary to confirm that all the sodium in the pipeline has been discharged. At present, when inspecting and maintaining sodium-related pipelines on site, it is only possible to judge whether the sodium in the pipeline has been completely discharged through pipeline purging and experience. It is impossible to accurately detect whether there is sodium in the pipeline, which brings risks to the maintenance of sodium-related pipelines. Summary of the invention

[0003] Based on this, it is necessary to provide a method for detecting sodium in sodium-related pipelines to address the problem of being unable to determine whether there is sodium in the pipeline during on-site sodium-related pipeline maintenance. This method can simply and quickly detect whether there is sodium in the sodium-related pipeline, thereby ensuring the safety of sodium-related pipeline maintenance operations.

[0004] In order to achieve the above object, the present invention provides the following technical solutions:

[0005] A method for detecting sodium in a sodium-related pipeline comprises the following steps:

[0006] 1. Perform local heating on one side of the sodium-related pipeline as the heating side of the sodium-related pipeline; and use the opposite side of the sodium-related pipeline as the non-heating side of the sodium-related pipeline;

[0007] 2. Measure the temperature of the heating side and non-heating side of the sodium-related pipeline at the same time;

[0008] 3. Determine whether there is sodium in the sodium-related pipeline and calculate the amount of sodium in the sodium-related pipeline by the temperature difference between the heating side and the non-heating side of the sodium-related pipeline;

[0009] The temperature difference when there is sodium in the sodium-related pipeline is smaller than the temperature difference when there is no sodium in the sodium-related pipeline.

[0010] Working principle: Sodium-related pipelines are austenitic stainless steel pipes. There is a significant difference between the thermal conductivity of austenitic stainless steel and that of sodium. The thermal conductivity of austenitic stainless steel is 16.2W / (m·℃), the thermal conductivity of solid sodium at 50℃ is 127.25W / (m·K), and the thermal conductivity of liquid sodium at 200℃ is 82.00W / (m·K). It can be seen that the thermal conductivity of sodium is higher than that of austenitic stainless steel.

[0011] When there is sodium in the sodium-related pipeline, the thermal conductivity of sodium is higher than that of austenitic stainless steel. At the same time, the thermal conductivity section thickness of the sodium-related pipeline is the sum of the wall thickness of the sodium-related pipeline and the inner diameter of the sodium-related pipeline, resulting in a small temperature difference between the heating side and the non-heating side of the sodium-related pipeline; when there is no sodium in the sodium-related pipeline, the thermal conductivity of austenitic stainless steel is lower than that of sodium. At the same time, the thermal conductivity section thickness of the sodium-related pipeline is the wall thickness of the sodium-related pipeline, resulting in a large temperature difference between the heating side and the non-heating side of the sodium-related pipeline.

[0012] Furthermore, the method for detecting the presence of sodium in a sodium-related pipeline specifically comprises the following steps:

[0013] 1. Remove the insulation equipment covering the surface of the sodium-related pipeline and clean the surface of the sodium-related pipeline;

[0014] 2. Install a heating source and a first temperature measuring point on the upper side of the sodium-related pipeline, and install a second temperature measuring point at a position corresponding to the first temperature measuring point on the lower side of the sodium-related pipeline;

[0015] 3. Re-wrap the insulation equipment on the surface of the sodium-related pipeline;

[0016] 4. Start the heating source to heat the sodium-related pipeline and read the temperatures of the first temperature measuring point and the second temperature measuring point;

[0017] 5. When the temperatures of the first temperature measuring point and the second temperature measuring point are stable, determine whether there is sodium in the sodium-related pipeline and calculate the amount of sodium in the sodium-related pipeline based on the temperature difference between the first temperature measuring point and the second temperature measuring point.

[0018] Furthermore, the heating source is an electric heating wire, and the temperatures of the first temperature measuring point and the second temperature measuring point are measured by a temperature measuring couple.

[0019] In one embodiment, the sodium-related pipeline is a DN80 austenitic stainless steel pipe, the heating power of the heating source is 250W, and the inner diameter of the sodium-related pipeline is 80mm;

[0020] When the temperature difference between the first temperature measuring point and the second temperature measuring point is 19℃≤≤20℃, it is judged that there is no sodium in the sodium-related pipeline;

[0021] When 0℃≤the temperature difference between the first temperature measuring point and the second temperature measuring point≤1℃, it is judged that the sodium-related pipeline is full of sodium;

[0022] When 1℃<the temperature difference between the first temperature measuring point and the second temperature measuring point≤10℃, the liquid level height h of sodium in the sodium-related pipeline is calculated according to formula 1:

[0023] Formula 1:

[0024] When 10℃<the temperature difference between the first temperature measuring point and the second temperature measuring point<19℃, the liquid level height h of sodium in the sodium-related pipeline is calculated according to Formula 2:

[0025] Formula 2:

[0026] Among them, T is the temperature difference between the first temperature measuring point and the second temperature measuring point, and R is the inner radius of the sodium-related pipeline.

[0027] In one embodiment, the sodium-related pipeline is a DN40 austenitic stainless steel pipe, the heating power of the heating source is 125W, and the inner diameter of the sodium-related pipeline is 40mm;

[0028] When the temperature difference between the first temperature measuring point and the second temperature measuring point is 11°C or less and ≤12°C, it is judged that there is no sodium in the sodium-related pipeline;

[0029] When 0℃≤the temperature difference between the first temperature measuring point and the second temperature measuring point≤1℃, it is judged that the sodium-related pipeline is full of sodium;

[0030] When 1℃<the temperature difference between the first temperature measuring point and the second temperature measuring point≤6℃, the liquid level height h of sodium in the sodium-related pipeline is calculated according to Formula 3:

[0031] Formula 3:

[0032] When 6℃<the temperature difference between the first temperature measuring point and the second temperature measuring point<12℃, the liquid level height h of sodium in the sodium-related pipeline is calculated according to Formula 4:

[0033] Formula 4:

[0034] Among them, T is the temperature difference between the first temperature measuring point and the second temperature measuring point, and R is the inner radius of the sodium-related pipeline.

[0035] In one embodiment, the sodium-related pipeline is a DN150 austenitic stainless steel pipe, the heating power of the heating source is 400W, and the inner diameter of the sodium-related pipeline is 150mm;

[0036] When the temperature difference between the first temperature measuring point and the second temperature measuring point is 34℃≤≤35℃, it is judged that there is no sodium in the sodium-related pipeline;

[0037] When 1°C≤the temperature difference between the first temperature measuring point and the second temperature measuring point≤2°C, it is judged that the sodium-related pipeline is full of sodium;

[0038] When 2℃<the temperature difference between the first temperature measuring point and the second temperature measuring point≤17℃, the liquid level height h of sodium in the sodium-related pipeline is calculated according to Formula 5:

[0039] Formula 5:

[0040] When 17℃<the temperature difference between the first temperature measuring point and the second temperature measuring point<34℃, the liquid level height h of sodium in the sodium-related pipeline is calculated according to Formula 6:

[0041] Formula 6:

[0042] Among them, T is the temperature difference between the first temperature measuring point and the second temperature measuring point, and R is the inner radius of the sodium-related pipeline.

[0043] Beneficial technical effects of the present invention:

[0044] The method for detecting the presence of sodium in a sodium-related pipeline of the present invention utilizes the difference in thermal conductivity between austenitic stainless steel and sodium and the temperature difference generated after heating to determine whether sodium exists in the sodium-related pipeline and calculate the amount of sodium in the sodium-related pipeline. The measuring principle is simple, the measuring result is accurate, and the measuring reaction speed is fast. It only takes 30-60 minutes to determine whether sodium exists in the sodium-related pipeline, and it only takes 2-3 hours to analyze the amount of sodium in the sodium-related pipeline. The measuring equipment includes an electric heating wire and a temperature measuring couple, and the measuring equipment is simple, reliable, low-cost, and has good benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 It is a schematic diagram of the principle of the method for detecting the presence of sodium in a sodium-related pipeline of the present invention.

[0046] In the figure, 1. sodium-related pipeline; 2. heating source; 3. first temperature measuring point; 4. second temperature measuring point. DETAILED DESCRIPTION

[0047] The technical solution of the present invention is described clearly and completely below in conjunction with the accompanying drawings and specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0048] The present invention provides a method for detecting sodium in a sodium-related pipeline, comprising the following steps:

[0049] 1. Perform local heating on one side of the sodium-related pipeline as the heating side of the sodium-related pipeline; and use the opposite side of the sodium-related pipeline as the non-heating side of the sodium-related pipeline;

[0050] 2. Measure the temperature of the heating side and non-heating side of the sodium-related pipeline at the same time;

[0051] 3. Determine whether there is sodium in the sodium-related pipeline and calculate the amount of sodium in the sodium-related pipeline by the temperature difference between the heating side and the non-heating side of the sodium-related pipeline; the temperature difference when there is sodium in the sodium-related pipeline is smaller than the temperature difference when there is no sodium in the sodium-related pipeline.

[0052] Working principle: Sodium-related pipelines are austenitic stainless steel pipes. There is a significant difference between the thermal conductivity of austenitic stainless steel and that of sodium. The thermal conductivity of austenitic stainless steel is 16.2W / (m·℃), the thermal conductivity of solid sodium at 50℃ is 127.25W / (m·K), and the thermal conductivity of liquid sodium at 200℃ is 82.00W / (m·K). It can be seen that the thermal conductivity of sodium is higher than that of austenitic stainless steel.

[0053] When there is sodium in the sodium-related pipeline, the thermal conductivity of sodium is higher than that of austenitic stainless steel. At the same time, the thermal conductivity section thickness of the sodium-related pipeline is the sum of the wall thickness of the sodium-related pipeline and the inner diameter of the sodium-related pipeline, resulting in a small temperature difference between the heating side and the non-heating side of the sodium-related pipeline; when there is no sodium in the sodium-related pipeline, the thermal conductivity of austenitic stainless steel is lower than that of sodium. At the same time, the thermal conductivity section thickness of the sodium-related pipeline is the wall thickness of the sodium-related pipeline, resulting in a large temperature difference between the heating side and the non-heating side of the sodium-related pipeline.

[0054] Further, see Figure 1 The method for detecting the presence of sodium in sodium-related pipelines specifically comprises the following steps:

[0055] 1. Remove the insulation equipment covering the surface of the sodium-related pipeline 1 and clean the surface of the sodium-related pipeline 1;

[0056] 2. Install a heating source 2 and a first temperature measuring point 3 on the upper side of the sodium-related pipeline 1, and install a second temperature measuring point 4 at a position corresponding to the first temperature measuring point 3 on the lower side of the sodium-related pipeline 1;

[0057] 3. Re-wrap the insulation equipment on the surface of the sodium-related pipeline;

[0058] 4. Start the heating source 2 to heat the sodium-related pipeline 1 and read the temperatures of the first temperature measuring point 3 and the second temperature measuring point 4;

[0059] 5. When the temperatures of the first temperature measuring point 3 and the second temperature measuring point 4 are stable, determine whether there is sodium in the sodium-related pipeline 1 and calculate the amount of sodium in the sodium-related pipeline 1 according to the temperature difference between the first temperature measuring point 3 and the second temperature measuring point 4.

[0060] Furthermore, the heating source 2 is an electric heating wire, and the temperatures of the first temperature measuring point 3 and the second temperature measuring point 4 are measured by a temperature measuring couple.

[0061] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0062] Example 1

[0063] This embodiment provides a method for detecting sodium in a sodium-related pipeline, comprising the following steps:

[0064] 1. Remove the insulation equipment covering the surface of the sodium-related pipeline 1 and clean the surface of the sodium-related pipeline 1;

[0065] 2. Install a heating source 2 and a first temperature measuring point 3 on the upper side of the sodium-related pipeline 1, and install a second temperature measuring point 4 at a position corresponding to the first temperature measuring point 3 on the lower side of the sodium-related pipeline 1;

[0066] 3. Re-wrap the insulation equipment on the surface of the sodium-related pipeline;

[0067] 4. Start the heating source 2 to heat the sodium-related pipeline 1 and read the temperatures of the first temperature measuring point 3 and the second temperature measuring point 4;

[0068] 5. When the temperatures of the first temperature measuring point 3 and the second temperature measuring point 4 are stable, determine whether there is sodium in the sodium-related pipeline 1 and calculate the amount of sodium in the sodium-related pipeline 1 according to the temperature difference between the first temperature measuring point 3 and the second temperature measuring point 4.

[0069] In this embodiment, the heating source 2 is an electric heating wire, and the temperatures of the first temperature measuring point 3 and the second temperature measuring point 4 are measured by a temperature measuring couple.

[0070] In this embodiment, the sodium-related pipeline 1 is a DN80 austenitic stainless steel pipe, and the heating power of the heating source 3 is 250W; the wall thickness of the sodium-related pipeline 1 is 9mm, and the inner diameter of the sodium-related pipeline 1 is 80mm; when there is no sodium in the sodium-related pipeline 1, the thickness of the heat-conducting cross-section of the sodium-related pipeline 1 is 9mm; when the sodium-related pipeline 1 is full of sodium, the thickness of the heat-conducting cross-section of the sodium-related pipeline 1 is 89mm;

[0071] When 19°C ≤ the temperature difference between the first temperature measuring point 3 and the second temperature measuring point 4 ≤ 20°C, it is determined that there is no sodium in the sodium-related pipeline 1;

[0072] When 0°C ≤ the temperature difference between the first temperature measuring point 3 and the second temperature measuring point 4 ≤ 1°C, it is determined that the sodium-related pipeline 1 is full of sodium;

[0073] When 1°C<the temperature difference between the first temperature measuring point 3 and the second temperature measuring point 4≤10°C, the liquid level h of sodium in the sodium-related pipeline 1 is calculated according to Formula 1:

[0074] Formula 1:

[0075] When 10℃<the temperature difference between the first temperature measuring point 3 and the second temperature measuring point 4<19℃, the liquid level height h of sodium in the sodium-related pipeline 1 is calculated according to Formula 2:

[0076] Formula 2:

[0077] Wherein, T is the temperature difference between the first temperature measuring point 3 and the second temperature measuring point 4 , and R is the inner radius of the sodium-related pipeline 1 .

[0078] Example 2

[0079] This embodiment provides a method for detecting sodium in a sodium-related pipeline, comprising the following steps:

[0080] 1. Remove the insulation equipment covering the surface of the sodium-related pipeline 1 and clean the surface of the sodium-related pipeline 1;

[0081] 2. Install a heating source 2 and a first temperature measuring point 3 on the upper side of the sodium-related pipeline 1, and install a second temperature measuring point 4 at a position corresponding to the first temperature measuring point 3 on the lower side of the sodium-related pipeline 1;

[0082] 3. Re-wrap the insulation equipment on the surface of the sodium-related pipeline;

[0083] 4. Start the heating source 2 to heat the sodium-related pipeline 1 and read the temperatures of the first temperature measuring point 3 and the second temperature measuring point 4;

[0084] 5. When the temperatures of the first temperature measuring point 3 and the second temperature measuring point 4 are stable, determine whether there is sodium in the sodium-related pipeline 1 and calculate the amount of sodium in the sodium-related pipeline 1 according to the temperature difference between the first temperature measuring point 3 and the second temperature measuring point 4.

[0085] In this embodiment, the heating source 2 is an electric heating wire, and the temperatures of the first temperature measuring point 3 and the second temperature measuring point 4 are measured by a temperature measuring couple.

[0086] In this embodiment, the sodium-related pipeline 1 is a DN40 austenitic stainless steel pipe, the heating power of the heating source 2 is 125W, and the inner diameter of the sodium-related pipeline 1 is 40mm;

[0087] When 11°C ≤ the temperature difference between the first temperature measuring point 3 and the second temperature measuring point 4 ≤ 12°C, it is determined that there is no sodium in the sodium-related pipeline 1;

[0088] When 0°C ≤ the temperature difference between the first temperature measuring point 3 and the second temperature measuring point 4 ≤ 1°C, it is determined that the sodium-related pipeline 1 is full of sodium;

[0089] When 1°C<the temperature difference between the first temperature measuring point 3 and the second temperature measuring point 4≤6°C, the liquid level h of sodium in the sodium-related pipeline 1 is calculated according to Formula 3:

[0090] Formula 3:

[0091] When 6°C < the temperature difference between the first temperature measuring point 3 and the second temperature measuring point 4 < 12°C, the liquid level h of sodium in the sodium-related pipeline 1 is calculated according to Formula 4:

[0092] Formula 4:

[0093] Wherein, T is the temperature difference between the first temperature measuring point 3 and the second temperature measuring point 4 , and R is the inner radius of the sodium-related pipeline 1 .

[0094] Example 3

[0095] This embodiment provides a method for detecting sodium in a sodium-related pipeline, comprising the following steps:

[0096] 1. Remove the insulation equipment covering the surface of the sodium-related pipeline 1 and clean the surface of the sodium-related pipeline 1;

[0097] 2. Install a heating source 2 and a first temperature measuring point 3 on the upper side of the sodium-related pipeline 1, and install a second temperature measuring point 4 at a position corresponding to the first temperature measuring point 3 on the lower side of the sodium-related pipeline 1;

[0098] 3. Re-wrap the insulation equipment on the surface of the sodium-related pipeline;

[0099] 4. Start the heating source 2 to heat the sodium-related pipeline 1 and read the temperatures of the first temperature measuring point 3 and the second temperature measuring point 4;

[0100] 5. When the temperatures of the first temperature measuring point 3 and the second temperature measuring point 4 are stable, determine whether there is sodium in the sodium-related pipeline 1 and calculate the amount of sodium in the sodium-related pipeline 1 according to the temperature difference between the first temperature measuring point 3 and the second temperature measuring point 4.

[0101] In this embodiment, the heating source 2 is an electric heating wire, and the temperatures of the first temperature measuring point 3 and the second temperature measuring point 4 are measured by a temperature measuring couple.

[0102] In this embodiment, the sodium-related pipeline 1 is a DN150 austenitic stainless steel pipe, the heating power of the heating source 2 is 400W, and the inner diameter of the sodium-related pipeline 1 is 150mm;

[0103] When 34°C ≤ the temperature difference between the first temperature measuring point 3 and the second temperature measuring point 4 ≤ 35°C, it is determined that there is no sodium in the sodium-related pipeline 1;

[0104] When 1°C ≤ the temperature difference between the first temperature measuring point 3 and the second temperature measuring point 4 ≤ 2°C, it is determined that the sodium-related pipeline 1 is full of sodium;

[0105] When 2°C<the temperature difference between the first temperature measuring point 3 and the second temperature measuring point 4≤17°C, the liquid level h of sodium in the sodium-related pipeline 1 is calculated according to Formula 5:

[0106] Formula 5:

[0107] When 17°C < the temperature difference between the first temperature measuring point 3 and the second temperature measuring point 4 < 34°C, the liquid level h of sodium in the sodium-related pipeline 1 is calculated according to Formula 6:

[0108] Formula 6:

[0109] Wherein, T is the temperature difference between the first temperature measuring point 3 and the second temperature measuring point 4 , and R is the inner radius of the sodium-related pipeline 1 .

[0110] The embodiments of the present invention provide a method for detecting the presence of sodium in sodium-related pipes of several typical sizes. The measuring principle is simple, the measuring results are accurate and reliable, and the measuring reaction speed is fast. It only takes 30-60 minutes to determine whether sodium exists in the sodium-related pipe, and only takes 2-3 hours to analyze the amount of sodium in the sodium-related pipe.

[0111] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A method for detecting sodium in a sodium-related pipeline, characterized in that: The steps include: Step 1: Locally heat one side of the sodium-related pipeline (1) to serve as the heated side of the sodium-related pipeline (1); and use the side opposite to the heated side of the sodium-related pipeline (1) as the non-heated side of the sodium-related pipeline (1); Step 2, measuring the temperature of the heated side and the non-heated side of the sodium-related pipeline (1) at the same time; Step 3, judging whether there is sodium in the sodium-related pipeline (1) and calculating the amount of sodium in the sodium-related pipeline (1) by the temperature difference between the heated side and the non-heated side of the sodium-related pipeline (1); The magnitude of the temperature difference when there is sodium in the sodium-related pipeline (1) is smaller than the magnitude of the temperature difference when there is no sodium in the sodium-related pipeline (1).

2. The method for detecting sodium in sodium-related pipelines according to claim 1, characterized in that: The specific steps include: Step 1, removing the heat preservation device coated on the surface of the sodium-related pipeline (1) and cleaning the surface of the sodium-related pipeline (1); Step 2: installing a heating source (2) and a first temperature measuring point (3) on the upper side of the sodium-related pipeline (1), and installing a second temperature measuring point (4) at a position corresponding to the first temperature measuring point (3) on the lower side of the sodium-related pipeline (1); Step 3, re-wrapping the heat preservation device on the surface of the sodium-related pipeline (1); Step 4, starting the heating source (2) to heat the sodium-related pipeline (1) and reading the temperatures of the first temperature measuring point (3) and the second temperature measuring point (4); Step 5: When the temperatures of the first temperature measuring point (3) and the second temperature measuring point (4) are stable, judging whether there is sodium in the sodium-related pipeline (1) and calculating the amount of sodium in the sodium-related pipeline (1) based on the temperature difference between the first temperature measuring point (3) and the second temperature measuring point (4).

3. The method for detecting sodium in a sodium-related pipeline (1) according to claim 2, characterized in that: The heating source (2) is an electric heating wire, and the temperatures of the first temperature measuring point (3) and the second temperature measuring point (4) are measured by a temperature measuring thermocouple.

4. The method for detecting sodium in sodium-related pipelines according to claim 3, characterized in that: The sodium-related pipeline (1) is a DN80 austenitic stainless steel pipe, the heating power of the heating source (2) is 250W, and the inner diameter of the sodium-related pipeline (1) is 80mm; When the temperature difference between the first temperature measuring point (3) and the second temperature measuring point (4) is 19°C or less than or equal to 20°C, it is determined that there is no sodium in the sodium-related pipeline (1); When 0°C ≤ the temperature difference between the first temperature measuring point (3) and the second temperature measuring point (4) ≤ 1°C, it is determined that the sodium-related pipeline (1) is full of sodium; When 1°C < the temperature difference between the first temperature measuring point (3) and the second temperature measuring point (4) ≤ 10°C, the liquid level h of sodium in the sodium-related pipeline (1) is calculated according to Formula 1: Formula 1: When 10°C < the temperature difference between the first temperature measuring point (3) and the second temperature measuring point (4) < 19°C, the liquid level height h of sodium in the sodium-related pipeline (1) is calculated according to Formula 2: Formula 2: Wherein, T is the temperature difference between the first temperature measuring point (3) and the second temperature measuring point (4), and R is the inner radius of the sodium-related pipeline (1).

5. The method for detecting sodium in sodium-related pipelines according to claim 3, characterized in that: The sodium-related pipeline (1) is a DN40 austenitic stainless steel pipe, the heating power of the heating source (2) is 125W, and the inner diameter of the sodium-related pipeline (1) is 40mm; When the temperature difference between the first temperature measuring point (3) and the second temperature measuring point (4) is 11°C or less than or equal to 12°C, it is determined that there is no sodium in the sodium-related pipeline (1); When 0°C ≤ the temperature difference between the first temperature measuring point (3) and the second temperature measuring point (4) ≤ 1°C, it is determined that the sodium-related pipeline (1) is full of sodium; When 1°C < the temperature difference between the first temperature measuring point (3) and the second temperature measuring point (4) ≤ 6°C, the liquid level h of sodium in the sodium-related pipeline (1) is calculated according to Formula 3: Formula 3: When 6°C < the temperature difference between the first temperature measuring point (3) and the second temperature measuring point (4) < 12°C, the liquid level h of sodium in the sodium-related pipeline (1) is calculated according to Formula 4: Formula 4: Wherein, T is the temperature difference between the first temperature measuring point (3) and the second temperature measuring point (4), and R is the inner radius of the sodium-related pipeline (1).

6. The method for detecting sodium in sodium-related pipelines according to claim 3, characterized in that: The sodium-related pipeline (1) is a DN150 austenitic stainless steel pipe, the heating power of the heating source (2) is 400W, and the inner diameter of the sodium-related pipeline (1) is 150mm; When the temperature difference between the first temperature measuring point (3) and the second temperature measuring point (4) is 34°C or less than or equal to 35°C, it is determined that there is no sodium in the sodium-related pipeline (1); When the temperature difference between the first temperature measuring point (3) and the second temperature measuring point (4) is 1°C or less than or equal to 2°C, it is determined that the sodium-related pipeline (1) is full of sodium; When 2°C<the temperature difference between the first temperature measuring point (3) and the second temperature measuring point (4)≤17°C, the liquid level h of sodium in the sodium-related pipeline (1) is calculated according to Formula 5: Formula 5: When 17°C < the temperature difference between the first temperature measuring point (3) and the second temperature measuring point (4) < 34°C, the liquid level h of sodium in the sodium-related pipeline (1) is calculated according to Formula 6: Formula 6: Wherein, T is the temperature difference between the first temperature measuring point (3) and the second temperature measuring point (4), and R is the inner radius of the sodium-related pipeline (1).

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