Segmented liquid level meter flooding test method and system

Abstract

The invention relates to the technical field of nuclear power engineering, in particular to a segmented liquid level meter flooding test method and system.The flooding test method comprises the following steps that a to-be-tested segmented liquid level meter is fixed in an experiment bin according to test requirements; wherein the sectional liquid level meter is provided with a plurality of groups of measuring units which are in communication connection; spraying steam at a set temperature into the experiment cabin for a set time; a chemical solution with set components is injected into the experiment bin, in the multiple sets of measuring units, at least one set of measuring units is completely submerged by the chemical solution, at least one set of measuring units is partially submerged by the chemical solution, and at least one set of measuring units does not make contact with the chemical solution; controlling the temperature of the experiment cabin to be not lower than a set value and lasting for a set time; signals fed back by the sectional liquid level meter are monitored, and the reliability of the liquid level meter is verified according to the change condition of the signals.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of nuclear power engineering, in particular to a segmented liquid level meter flooding test method and system. BACKGROUND

[0002] The statements in this section merely provide background information related to the present application and do not necessarily constitute the prior art.

[0003] The containment of a large nuclear power plant needs to be measured for a long time after an accident condition to help the operator monitor the safety of the power plant or equipment, and to ensure that the nuclear fuel can be effectively submerged in water for a long time after a nuclear accident, and to ensure that radioactive substances will not spread to the public area outside the containment. Therefore, it is necessary to conduct a flooding experiment on the liquid level meter under the accident condition to ensure that it can maintain its performance under harsh conditions such as high temperature, chemical corrosion and long-term immersion when an accident occurs. However, the traditional industrial test cannot reproduce the complex conditions such as high temperature, chemical corrosion and long-term immersion after a nuclear accident, which may cause the instrument to fail in an actual accident.

[0004] Secondly, due to the large size of the containment, the liquid level meter is usually of a segmented structure, and the liquid level in different regions of the containment is obtained by multiple measuring sections. After the nuclear power plant accident, the liquid level in the containment changes dynamically, and the environment of different measuring sections is different. For example, the part of the liquid level meter that is completely submerged may be subjected to long-term immersion and corrosion by the liquid, the part of the liquid level meter that is not submerged (the top of the containment) may be subjected to high-temperature gas impact, and the dry-wet interface of the liquid level meter may have a problem of repeated switching of signals. However, the traditional industrial test method cannot simultaneously simulate the above-mentioned environments, and lacks an ideal verification method. SUMMARY

[0005] In order to solve the technical problems existing in the background art, the present application provides a segmented liquid level meter flooding test method and system, which simulates the extreme environment of the containment under the accident condition by means of steam spraying + chemical solution injection + long-term high-temperature immersion, covers the full-scene demand of liquid level monitoring, and verifies the reliability of the multi-section liquid level meter through the signal feedback of the liquid level meter.

[0006] In order to achieve the above-mentioned purpose, the present application adopts the following technical solutions: The first aspect of the present application provides a segmented liquid level meter flooding test method, comprising the following steps: According to the test requirements, the segmented liquid level meter to be tested is fixed inside the experimental chamber; wherein the segmented liquid level meter has multiple groups of measuring units connected in communication; Spray steam of a set temperature into the experimental chamber and continue for a set time; Injecting chemical solution of set components into the experimental chamber, in multiple groups of measuring units, at least one group of measuring units is completely submerged by the chemical solution, at least one group of measuring units is partially submerged by the chemical solution, and at least one group of measuring units is not in contact with the chemical solution; Controlling the temperature of the experimental chamber to be no less than a set value and lasting for a set time; Monitoring the signals fed back by the segmented level gauge and verifying the reliability of the level gauge according to the signal change.

[0007] Further, spraying steam of a set temperature into the experimental chamber and lasting for a set time, specifically, spraying steam of more than 200°C into the experimental chamber and lasting for at least 10 hours, for simulating the working condition in the accident outbreak stage.

[0008] Further, the experimental chamber has at least one, when the number of experimental chambers is one, the multiple groups of measuring units are located at different height positions of the experimental chamber.

[0009] Further, when the number of experimental chambers is one, by injecting chemical solution of a set volume, at least one group of measuring units is completely submerged by the chemical solution, at least one group of measuring units is partially submerged by the chemical solution, and at least one group of measuring units is not in contact with the chemical solution.

[0010] Further, when the number of experimental chambers is more than one, each experimental chamber contains the same or different number of measuring units.

[0011] Further, when the number of experimental chambers is more than one, by controlling the volume of the chemical solution injected into each experimental chamber, at least one group of measuring units is completely submerged by the chemical solution, at least one group of measuring units is partially submerged by the chemical solution, and at least one group of measuring units is not in contact with the chemical solution.

[0012] Further, by injecting chemical solution into the experimental chamber, the working condition in the emergency cooling stage is simulated, by controlling the chemical solution to completely submerge the measuring units, partially submerge the measuring units and not contact the measuring units, the performance of the segmented level gauge in different working conditions is distinguished.

[0013] Further, the temperature of the experimental chamber is controlled to be no less than a set value and lasts for a set time, specifically, the temperature of the experimental chamber is controlled to be no less than 90°C and lasts for at least 100 days, for simulating the high-temperature monitoring stage in the late accident.

[0014] Further, the interruption is allowed during the monitoring of the feedback signals of the segmented level gauge, the interruption time is not counted into the accumulated time length of the monitoring, and the device arrangement and the chemical solution level after the interruption are consistent with those before the interruption.

[0015] The second aspect of the present application provides a segmented level gauge flooding test system, comprising: An experimental bin is used to accommodate the segmented liquid level meter to be tested, and a spray head is arranged inside the bin to spray steam at a set temperature; A chemical solution injection unit is used to inject a chemical solution of a set component into the experimental bin; A temperature control unit is used to control the temperature of the experimental bin to be maintained within a set range; A monitoring unit is used to receive the signals fed back by the segmented liquid level meter to be tested.

[0016] Compared with the prior art, the above one or more technical solutions have the following beneficial effects: 1. First, the steam spraying is used to simulate the high-temperature steam impact in the accident outbreak stage to verify the sealing performance and heat resistance of the liquid level meter. Second, the injection of the chemical solution is used to simulate the emergency cooling stage during the accident to test the performance of the liquid level meter in the real accident liquid, including corrosion resistance, signal accuracy, and liquid level monitoring capability, etc. Finally, the long-term high-temperature monitoring is used to simulate the reliability of the liquid level meter in the long-term monitoring stage after the accident to expose potential problems.

[0017] 2. The size of the containment vessel and the liquid level range are huge, and the liquid level can dynamically change from the bottom (completely submerged) to the top (dry area). According to the structural characteristics of the segmented liquid level meter having multiple measuring units, the completely submerged measuring unit is used to simulate the pit water injection working condition to verify the stability of the instrument under long-term immersion. The partially submerged measuring unit is used to simulate the liquid level fluctuation transition zone to verify the signal switching capability at the dry-wet interface. The un-submerged measuring unit is used to verify the anti-interference performance of the liquid level meter in the high-temperature steam environment.

[0018] 3. Through the steam spraying + chemical solution injection + long-term high-temperature immersion mode, the extreme environment of the containment vessel under accident conditions is simulated to cover the full-scene demand of liquid level monitoring. The reliability of the multi-segmented liquid level meter is verified through the signal condition fed back by the liquid level meter. BRIEF DESCRIPTION OF DRAWINGS

[0019] The drawings accompanying the specification of this application form a part thereof, serve to provide further understanding of the application, and together with the description of the exemplary embodiments of the application given below, explain the application, and do not constitute an improper limitation of the application.

[0020] Figure 1 is a schematic diagram of the water flooding test process of the segmented liquid level meter provided by one or more embodiments of the application; Figure 2 is a structural schematic diagram of the segmented liquid level meter provided by one or more embodiments of the application; Figure 3 is a structural schematic diagram of the water flooding test of the segmented liquid level meter provided by one or more embodiments of the application; Figure 4is a water level diagram during water flooding test provided by one or more embodiments of the present application; Figure 5 is a structural diagram of water flooding test using three experimental bins provided by one or more embodiments of the present application; Figure 6 is a structural diagram of water flooding test using two experimental bins (experimental bin A is injected with water) provided by one or more embodiments of the present application; Figure 7 is a structural diagram of water flooding test using two experimental bins (experimental bin B is injected with water) provided by one or more embodiments of the present application.

[0021] In the figure: 10 monitoring unit, 11 measurement unit A, 12 measurement unit B, 13 measurement unit C, 20 experimental bin, 21 experimental bin A, 22 experimental bin B, 23 experimental bin C, 30 through-piece, 40 spray head. DETAILED DESCRIPTION

[0022] The present application will be further described below in conjunction with the accompanying drawings and embodiments.

[0023] It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs.

[0024] Term explanation: Containment, one of the most important safety barriers of nuclear power plants, its core function is to prevent radioactive material from leaking into the environment, especially in the case of an accident (such as reactor coolant leakage or core meltdown).

[0025] Containment is usually made of prestressed concrete or steel-lined concrete, with a thickness of more than 1 meter, capable of withstanding extreme pressure (such as internal explosion, aircraft impact, etc.), and together with fuel pellet cladding and reactor pressure vessel, it constitutes three safety barriers.

[0026] Containment is equipped with a liquid level meter to monitor the water level in the containment. In the case of an accident, cooling water needs to be injected into the containment, which may cause the water level in the containment to rise from dry state (before the accident) to several meters deep (after the accident). The liquid level meter and the containment are subjected to extreme conditions such as high temperature, high pressure, radiation, etc.

[0027] As introduced in the background technology, in order to ensure that the liquid level meter can maintain its existing performance under accident conditions, it is necessary to conduct a water flooding test on the liquid level meter under accident conditions. The liquid level meter has a segmented structure, and the special working conditions after the accident have different impacts on different measuring sections of the liquid level meter. Traditional industrial experimental methods cannot reproduce the complex conditions such as high temperature, chemical corrosion, and long-term immersion after a nuclear accident for different measuring sections of the liquid level meter, resulting in unsatisfactory verification methods.

[0028] Therefore, the following embodiments provide a method and system for a submerged liquid level gauge flooding test, which is suitable for testing liquid level instruments in specific scenarios such as nuclear power plant containment and pits. The system provides the components required for the test and the layout requirements of the components under the submerged liquid level test, and clarifies the test sequence for liquid level instruments such as containment and pits after an accident. This system can fully verify the performance of the submerged liquid level gauge after a nuclear accident in a nuclear power plant.

[0029] Example 1: like Figure 1 As shown, the submerged level gauge flooding test method includes the following steps: According to the test requirements, the segmented liquid level gauge to be tested is fixed inside the experimental chamber; wherein the segmented liquid level gauge has multiple groups of measuring units connected by communication; Spray steam of set temperature into the experimental chamber for set time; A chemical solution of set components is injected into the experimental chamber, wherein among the multiple groups of measuring units, at least one group of measuring units is completely submerged in the chemical solution, at least one group of measuring units is partially submerged in the chemical solution, and at least one group of measuring units is not in contact with the chemical solution; Control the temperature of the experimental chamber to not be lower than the set value and maintain it for the set time; Monitor the feedback signal of the segmented level gauge and verify the reliability of the level gauge based on the signal changes.

[0030] like Figure 2 As shown, the segmented liquid level gauge includes three groups of measuring units, including measuring unit A11, measuring unit B12 and measuring unit C13. The measuring units are connected by cables. The measuring unit located at the head end or the end end is connected to the monitoring unit 10 to transmit the acquired liquid level signal to the external monitoring device.

[0031] like Figure 3 As shown, during the flooding test, the segmented liquid level gauge is located inside the experimental chamber 20 and arranged at different height positions of the experimental chamber 20. The cable for transmitting the signal passes through the penetration piece 30 and out of the experimental chamber 20 to be connected to the monitoring unit 10 located outside the experimental chamber 20.

[0032] For example, the measurement unit A11 is arranged at the bottom of the experimental chamber 20, the measurement unit B12 is arranged higher than the measurement unit A11, and the measurement unit C13 is arranged at the top of the experimental chamber 20 and higher than the measurement unit B12. The measurement unit C13 is connected to the long-term monitoring device outside the experimental chamber 20 through the cable penetrating the experimental chamber 20 through the penetrating member 30.

[0033] As shown in Figure 4 , the experimental chamber 20 is provided with a spray head 40 for spraying steam of a set temperature and pressure into the experimental chamber 20.

[0034] After the spraying is completed, a chemical solution mainly composed of boric acid is injected into the experimental chamber 20 to ensure that the solution completely covers the measurement unit A11, partially covers the measurement unit B12 (not completely covered), and does not contact the measurement unit C13. The water level formed is shown in Figure 4 .

[0035] Since the boron-10 isotope has a very high neutron absorption cross section, it can effectively capture free neutrons in the nuclear reactor. After the accident, the containment spray system or the core cooling system injects a boric acid solution into the core or the containment sump. The high-concentration boric acid solution quickly terminates the nuclear fission chain reaction, and has the functions of cooling and preventing recriticality. At the same time, boric acid can inhibit the corrosive oxides produced by water radiolysis, protecting metal structures such as stainless steel pipes. Correspondingly, the liquid level meter is installed on the inner wall of the containment, which also bears the flushing from the boric acid solution.

[0036] After the injection of the chemical solution is completed, the temperature of the experimental chamber 20 is increased, and finally maintained at an environment not lower than 90°C.

[0037] The way of heating the experimental chamber 20 is not limited, for example, steam re-spraying or electric heating device can be used. In this embodiment, in order to reduce the influence on the liquid level disturbance, the electric heating method is preferred. A heating sleeve can be arranged in the experimental chamber 20, and the medium in the sleeve carries heat to circulate between the internal and external heat sources of the experimental chamber 20 to achieve heating.

[0038] In this embodiment, the upper limit of the temperature is not limited, and only the lower limit of the temperature is limited to 90°C. Considering the difference in environmental conditions of different reactor types, the upper limit of the temperature here can be set to 120°C as an example.

[0039] The water level in the experimental chamber 20 is maintained without changes other than normal fluctuations. The signal of the liquid level meter is monitored by the long-term monitoring device outside the experimental chamber 20, and the monitoring cumulative duration is not less than 100 days. During the test period, the signal does not exceed the corresponding accuracy requirement, and it is considered that the reliability meets the demand.

[0040] Boric acid can accelerate the corrosion of metals (such as carbon steel, copper alloy) and non-metals (such as sealing rubber, cable insulation) at high temperatures (≥ 90℃), which may affect the ability of sensors, circuits and other signal transmission and processing in the liquid level meter. At the same time, the conductivity of boric acid solution may affect the signal stability of electrical liquid level meter (such as admittance probe). After the nuclear accident, the liquid accumulated in the containment sump is a coolant mixture containing high concentration of boric acid (may also contain fission products, impurities, etc.). The liquid level meter must work reliably in such a solution for a long time, so this scheme strictly replicates this chemical environment.

[0041] The test is allowed to be interrupted during the monitoring period, and the interruption time is not included in the monitoring cumulative duration. After the test is resumed, the test equipment arrangement and the water level of the test chemical solution should be basically consistent with the original test period.

[0042] As shown in Figure 5 , three measuring units are arranged in three experimental chambers respectively, and the three measuring units are connected by cables, and the three measuring units are simulated by chemical solvent submergence, semi-submergence and non-submergence.

[0043] For example: measuring unit A11 is located in experimental chamber A21, measuring unit B12 is located in experimental chamber B22, and measuring unit C13 is located in experimental chamber C23. The three measuring units are connected by cables, and the three measuring units are at the same height position and are subjected to steam spraying and then chemical solution immersion; among them, the liquid level height in experimental chamber A2 exceeds measuring unit A11 and is in submerged state, the liquid level height in experimental chamber B22 is in the middle of measuring unit B12 and is in semi-submerged state, and experimental chamber C23 is not injected with chemical solution. Through the above design, the different immersion states of the segmented liquid level meter under accident conditions are simulated Two experimental chambers can also be used.

[0044] As shown in Figure 6 , measuring unit A11 and measuring unit B12 are located in experimental chamber A21, and the height of measuring unit A11 is lower than that of measuring unit B12. Measuring unit C13 is located in experimental chamber B22, and the three measuring units are connected by cables. Experimental chamber A21 is injected with about 50% of the total volume of chemical solution, so that measuring unit A11 is in submerged state and measuring unit B12 is in semi-submerged state. Experimental chamber B22 is not injected with chemical solution.

[0045] As shown in Figure 7As shown, the measurement unit A11 is located in the experimental bin A21, the measurement unit B12 and the measurement unit C13 are located in the experimental bin B22, the height of the measurement unit B12 is lower than that of the measurement unit C13, and the measurement units are connected through cables. The experimental bin A21 is injected with a chemical solution, so that the measurement unit A11 is in a submerged state, the experimental bin B22 is injected with about 50% of the total volume of the chemical solution, so that the measurement unit B12 is in a semi-submerged state, and the measurement unit C13 does not contact the chemical solution.

[0046] The core of the present scheme is to "realistically simulate the extreme environment of nuclear accidents", and to "cover the full-scene demand of liquid level monitoring". Nuclear power plant accidents (such as LOCA loss of coolant accident, core meltdown) will produce multiple superimposed extreme environments: High temperature and high pressure steam: the temperature in the containment vessel instantaneously rises to more than 200℃ in the early stage of the accident, accompanied by high pressure steam spraying; High concentration boric acid solution: the emergency cooling system injects water solution containing boric acid, which has the functions of cooling and preventing nuclear recriticality; Long-term high-temperature soaking: residual decay heat after the accident may cause the liquid in the containment vessel to remain at a high temperature (≥90℃) for a long time; Traditional industrial liquid level meters cannot withstand such a combination of harsh conditions and must be verified for reliability through full working condition simulation tests. The size of the containment vessel and the water level range are huge, and the water level may dynamically change from the pit (completely submerged) to the top (dry area). The present scheme combines the structural characteristics of the segmented liquid level meter to simulate the dynamic water level change under accident conditions, for example: Completely submerged (unit A): simulate the water injection condition to verify the stability of the instrument under long-term soaking; Partially submerged (unit B): simulate the water level fluctuation transition zone to test the signal switching ability at the dry-wet junction; Unsubmerged (unit C): verify the anti-interference ability of the instrument in the high-temperature steam environment (such as false signals caused by steam condensation).

[0047] In terms of specific test flow design, first, steam spraying is performed to reproduce the high-temperature steam impact at the onset of the accident, verify the instrument sealing (such as whether the cable penetration leaks), and the material heat resistance (such as whether the plastic parts are deformed), and the design is 200℃, far exceeding the tolerance limit of conventional industrial instruments, which are usually ≤85℃.

[0048] Secondly, boric acid solution injection is performed to simulate emergency cooling, with the purpose of testing the performance of the liquid level meter in the real accident liquid (boric acid + high temperature), including corrosion resistance, signal accuracy, and water level control ability.

[0049] Finally, through long-term high-temperature monitoring, the post-accident long-term (≥100 days) monitoring reliability of the liquid level meter is verified, and potential problems are exposed, such as material aging of the liquid level meter components (high-temperature degradation of the rubber sealing ring, and brittle of the cable insulation layer), and signal drift (long-term high-temperature calibration deviation).

[0050] Embodiment Two: The segmented liquid level meter flooding test system is used to implement the test method given in Embodiment One, and includes: The test chamber is used to accommodate the segmented liquid level meter to be tested, and is internally provided with a spray head for spraying steam at a set temperature; The chemical solution injection unit is used to inject a chemical solution of a set composition into the test chamber; The temperature control unit is used to control the temperature of the test chamber to be maintained within a set range; The monitoring unit is used to receive the signals fed back by the segmented liquid level meter to be tested.

[0051] As a further implementation, steam at a set temperature is sprayed into the test chamber and maintained for a set time, specifically: steam at more than 200°C is sprayed into the test chamber for at least 10 hours, to simulate the working conditions in the accident outbreak stage.

[0052] As a further implementation, the test chamber has at least one, and when the number of test chambers is one, multiple groups of measurement units are located at different height positions of the test chamber.

[0053] As a further implementation, when the number of test chambers is one, at least one group of measurement units is completely flooded by the chemical solution, at least one group of measurement units is partially flooded by the chemical solution, and at least one group of measurement units does not contact the chemical solution, by injecting a set volume of chemical solution.

[0054] As a further implementation, when the number of test chambers is more than one, each test chamber accommodates the same or different number of measurement units.

[0055] As a further implementation, when the number of test chambers is more than one, at least one group of measurement units is completely flooded by the chemical solution, at least one group of measurement units is partially flooded by the chemical solution, and at least one group of measurement units does not contact the chemical solution, by controlling the volume of chemical solution injected into each test chamber.

[0056] As a further implementation, the working conditions in the emergency cooling stage are simulated by injecting a chemical solution into the test chamber, and the performance of the segmented liquid level meter under different working conditions is distinguished by controlling the chemical solution to completely flood the measurement units, partially flood the measurement units, and not contact the measurement units, respectively.

[0057] As a further implementation, the temperature of the experimental chamber is controlled to be no less than a set value for a set time, specifically: the temperature of the experimental chamber is controlled to be no less than 90°C for at least 100 days, for simulating a high-temperature monitoring stage in a late post-accident stage.

[0058] As a further implementation, interruption is allowed during monitoring of the segmented level gauge feedback signal, and the interruption time is not counted into the monitoring cumulative time length; after the interruption, the device arrangement and the chemical solution level are restored to be consistent with those before the interruption.

[0059] First, steam spraying is used to simulate high-temperature steam impact in an accident outbreak stage, to verify the sealing property and heat resistance of the level gauge; second, injection of chemical solution is used to simulate an emergency cooling stage during an accident, to test the performance of the level gauge in real accident liquid, including corrosion resistance, signal accuracy and level monitoring capability, etc.; and finally, long-term high-temperature monitoring is used to simulate the reliability of the level gauge in a long-term monitoring stage in a late post-accident stage, to expose potential problems.

[0060] The size of the containment and the level range are huge, and the level can dynamically change from the bottom (completely submerged) to the top (dry area); according to the structural characteristics of the segmented level gauge having multiple measuring units, the completely submerged measuring unit is used to simulate a pit water injection working condition, to verify the stability of the instrument under long-term immersion; the partially submerged measuring unit is used to simulate a level fluctuation transition zone, to verify the signal switching capability at the dry-wet interface; and the un-submerged measuring unit is used to verify the anti-interference property of the level gauge in a high-temperature steam environment.

[0061] Through steam spraying + chemical solution injection + long-term high-temperature immersion, the extreme environment of the containment under accident conditions is simulated, covering the full-scenario requirement of level monitoring, and the reliability of the multi-segmented level gauge is verified through the signal condition of the level gauge feedback.

[0062] The above merely describes preferred embodiments of the present application but should not be used to limit the present application, and various changes and modifications can be made by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. The submerged test method for a segmented level gauge is characterized by: The following steps are involved: According to the test requirements, the segmented liquid level gauge to be tested is fixed inside the experimental chamber; wherein the segmented liquid level gauge has multiple groups of measuring units connected by communication; Spray steam of set temperature into the experimental chamber for set time; A chemical solution of set components is injected into the experimental chamber, wherein among the multiple groups of measuring units, at least one group of measuring units is completely submerged in the chemical solution, at least one group of measuring units is partially submerged in the chemical solution, and at least one group of measuring units is not in contact with the chemical solution; Control the temperature of the experimental chamber to not be lower than the set value and maintain it for the set time; Monitor the feedback signal of the segmented level gauge and verify the reliability of the level gauge based on the signal changes.

2. The submerged level gauge flooding test method according to claim 1, wherein: When the number of experimental chambers is one, multiple groups of measuring units are located at different heights of the experimental chambers.

3. The submerged testing method for a segmented liquid level gauge according to claim 2, wherein: When the number of experimental chambers is one, by injecting a set volume of chemical solution, at least one group of measuring units is completely submerged in the chemical solution, at least one group of measuring units is partially submerged in the chemical solution, and at least one group of measuring units is not in contact with the chemical solution.

4. The submerged testing method for a segmented liquid level gauge according to claim 1, wherein: When the number of experimental chambers exceeds one, each experimental chamber accommodates the same or different number of measurement units.

5. The submerged testing method for a segmented liquid level gauge according to claim 4, wherein: When there are more than one experimental chamber, the volume of chemical solution injected into each experimental chamber is controlled so that at least one group of measuring units is completely submerged in the chemical solution, at least one group of measuring units is partially submerged in the chemical solution, and at least one group of measuring units is not in contact with the chemical solution.

6. The submerged testing method for a segmented liquid level gauge according to claim 1, wherein: Steam of set temperature is sprayed into the experimental chamber for a set time. Specifically, steam exceeding 200°C is sprayed into the experimental chamber for at least 10 hours to simulate the working conditions at the outbreak stage of an accident.

7. The submerged testing method for a segmented liquid level gauge according to claim 1, wherein: By injecting chemical solutions into the experimental chamber, the working conditions of the emergency cooling stage are simulated. By controlling the chemical solutions to completely submerge the measuring unit, partially submerge the measuring unit, and not contact the measuring unit, the performance of the segmented level gauge under different working conditions is distinguished.

8. The submerged testing method for a segmented liquid level gauge according to claim 1, wherein: The temperature of the experimental chamber is controlled to be no lower than the set value and is maintained for the set time. Specifically, the temperature of the experimental chamber is controlled to be no lower than 90°C and is maintained for at least 100 days to simulate the high temperature monitoring stage in the later stage of the accident.

9. The submerged testing method for a segmented liquid level gauge according to claim 1, wherein: Interruptions are allowed during the monitoring of the feedback signal of the segmented liquid level gauge, and the interruption time is not included in the cumulative monitoring time; the equipment layout and chemical solution level after resumption of the interruption remain consistent with those before the interruption.

10. A segmented liquid level gauge flooding test system for implementing the method according to any one of claims 1 to 9, characterized in that: include: The experimental chamber is used to accommodate the segmented liquid level gauge to be tested, and is equipped with a spray head inside for spraying steam at a set temperature; Chemical solution injection unit, used to inject chemical solution of set components into the experimental chamber; Temperature control unit, used to control the temperature of the experimental chamber to maintain within the set range; The monitoring unit is used to receive the feedback signal from the segmented liquid level meter to be tested. Threshold value to determine the surrounding rock classification result.

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