A fuel rod fouling reproduction system, a fouling sampling method, and a fouling characterization method.

Abstract

This application discloses a fuel rod fouling reproduction system, a fuel rod fouling sampling method, and a fuel rod fouling characterization method. The fuel rod fouling sampling method is used to obtain fouling samples from the fouling reproduction system. It includes pressurizing the medium flow channel to a preset pressure, introducing a fouling reproduction agent into the medium flow channel, heating the fouling reproduction agent through a heating element to deposit corrosion products in the heating element, discharging the fouling reproduction agent from the shell assembly through a fast exhaust channel, and intercepting the heating element with deposited corrosion products to obtain the fouling sample. It can be seen that because the medium flow channel is pressurized to a preset pressure, the shell assembly maintains a high-pressure state continuously during fouling collection. Thus, after the fouling is collected on the heating element, the high-pressure state forces the fouling reproduction agent to be quickly discharged through the fast exhaust channel, thereby avoiding significant changes in the composition and porous structure of the fouling sample and ensuring accurate analytical results.

Description

Technical Field

[0001] This invention relates to the field of nuclear reactors, specifically to a fuel rod fouling reproduction system, fouling sampling, and fouling characterization method. Background Technology

[0002] During nuclear reactor operation, corrosion products such as Fe and Ni in the primary coolant are deposited on the cladding surface above the fuel elements under the influence of core subcooling and boiling, forming a thin layer of corrosion product deposits, known as fouling. The fouling is primarily composed of NiFe₂O₄ and forms a loose, porous structure on the fuel rod cladding surface, with an average pore size of 0.1-1 μm and a porosity of 40-70%. The porous structure of the fouling is crucial for analyzing core safety issues such as fouling-induced power shift and fouling-induced cladding corrosion; therefore, accurately characterizing the porous structure of the fouling is of great significance.

[0003] Due to the high temperature, high pressure, and high radioactivity within the reactor, directly observing or characterizing the fouling on the surface of fuel rods remains challenging. Researchers typically remove fouled fuel assemblies from the reactor and perform a series of operations, including transfer, cooling, and de-radioactive storage, to sample the fouling layer and analyze the porous structure of the fouling surface.

[0004] However, NiFe2O4 has reverse solubility. When fuel assemblies are removed from the actual reactor or after a series of operations such as transfer, cooling, storage and radioactive removal, the composition and porous structure of the fouling will change significantly. Therefore, the analysis results do not represent the corrosion product deposit layer in the actual reactor. Summary of the Invention

[0005] The present invention is made to solve the above-mentioned technical problems, and its purpose is to provide a fuel rod fouling reproduction system, a fouling sampling method and a fouling characterization method, which can effectively reproduce fouling that is representative of the actual reactor.

[0006] In a first aspect, this application discloses a fuel rod fouling reproduction system, including a fouling reproduction device. The fouling reproduction device includes a housing assembly and a heating element. The housing assembly is provided with a medium flow channel for accommodating the heating element and a quick discharge channel communicating with the medium flow channel. The medium flow channel is used to introduce a fouling reproduction agent and accommodate the heating element so that corrosive substances in the fouling reproduction agent can be deposited on the heating element.

[0007] Optionally, the housing assembly includes a number of sequentially detachably connected tubular units for through which a medium can pass.

[0008] Optionally, the housing assembly also includes a positioning grid, with a gap reserved at the junction of adjacent tubular units for the outer edge of the positioning grid to be engaged.

[0009] Optionally, the housing assembly includes a hoop, and adjacent tubular units are detachably connected by sleeved hoop.

[0010] Optionally, the pipe unit is divided into a first sealing seat assembly, a pressure-bearing pipe, and a second sealing seat assembly, with the medium flow channel sequentially passing through the second sealing seat assembly, the pressure-bearing pipe, and the first sealing seat assembly.

[0011] Optionally, the fouling reproduction system also includes a heat exchanger and a pump body. The shell assembly is provided with a medium inlet and a medium outlet that connect to the medium flow channel. The medium outlet and the medium inlet are interconnected to form a circulation loop for the fouling reproduction agent. Both the heat exchanger and the pump body are located in the circulation loop of the fouling reproduction agent.

[0012] Optionally, the dirt reproduction system also includes a power supply, the two poles of which are applied to both sides of the dirt collection section of the heating element to form a conductive circuit. The dirt collection section is the part of the heating element located in the housing assembly.

[0013] Secondly, this application discloses a method for sampling dirt, used in a dirt reproduction system to obtain dirt samples, the method comprising: The medium flow channel is pressurized to a preset pressure, and a dirt reproduction agent is introduced into the medium flow channel, wherein the preset pressure is greater than atmospheric pressure; The dirt reconstitution agent is heated by a heating element, causing the corrosive substances in the dirt reconstitution agent to deposit on the heating element. The fouling reproducible agent in the housing assembly is discharged through a quick-drain channel; The sample collection process includes: cutting off the heating element with deposited corrosion to obtain a dirt collection sample.

[0014] Optionally, the sample cutting process includes: Remove one tube unit to partially expose the heating element; Exposed portions of the heating element are cut off to obtain a dirt collection sample.

[0015] Optionally, removing a tube unit to partially expose the heating element also includes exposing the positioning grid at the corresponding position of the removed tube unit; The sample cutting process also includes removing the exposed positioning grid.

[0016] Optionally, after cutting off the exposed portion of the heating element to obtain a dirt collection sample, the sample cutting process further includes: The end of the dirt sample is cut off.

[0017] Optionally, removing a tube unit to partially expose the heating element also includes removing the clamp.

[0018] Optionally, the sample cutting process further includes: The dirt collection sample is taken segment by segment from the direction from the first sealing seat assembly to the second sealing seat assembly, or from the second sealing seat assembly to the first sealing seat assembly.

[0019] Optionally, before discharging the fouling reproducible agent from the housing assembly through the quick-drain channel, the method further includes: Shut down the pump and heat exchanger.

[0020] Optionally, the method further includes turning off the power before discharging the dirt reproducing agent from the housing assembly through the quick-drain channel.

[0021] Optionally, pressurizing the medium flow channel to a preset pressure and introducing a fouling reproducibility agent into the medium flow channel includes: A fouling reproducible agent at a first preset temperature is introduced into the medium flow channel; Heating a fouling reproducible agent using a heating element to deposit corrosive substances from the fouling reproducible agent onto the heating element includes: The dirt reconstitution agent is heated to a second preset temperature by a heating element, and the second preset temperature is greater than or equal to the first preset temperature.

[0022] Thirdly, this application discloses a method for characterizing dirt samples obtained in a dirt sampling method, including: Obtain several dirt cross sections on the dirt collection sample, and obtain the porosity of each dirt cross section; Based on several dirt cross sections and the pore ratio of each dirt cross section, the three-dimensional porosity of the dirt collection sample is obtained.

[0023] The beneficial effects of this invention are as follows: Because the medium flow channel is pressurized to the preset pressure, the shell assembly maintains a high-pressure state throughout the fouling process. When the fouling is collected on the heating element and the valve is opened, the high-pressure state inside the shell assembly forces the fouling reproduction agent to be quickly discharged through the fast discharge channel. This avoids significant changes in the composition and porous structure of the fouling sample when it is taken out or after a series of operations such as transfer, cooling, storage and radioactivity removal. In particular, it avoids the re-dissolving of NiFe2O4, which has reverse solubility, back into the fouling reproduction agent, thus ensuring that the analysis results are representative of the corrosion product deposits in the actual reactor. Attached Figure Description

[0024] The above-described features and advantages of the present invention will be better understood after reading the following detailed description of embodiments of the present disclosure in conjunction with the accompanying drawings. In the drawings, components are not necessarily drawn to scale, and components having similar related characteristics or features may have the same or similar reference numerals.

[0025] Figure 1This invention relates to a dirt reproduction system; Figure 2 This invention relates to a dirt reproduction device; Figure 3 This is the present invention. Figure 2 Enlarged view of point I; Figure 4 This is a schematic diagram showing the distribution of various components in the dirt reproduction device of the present invention; Figure 5 This is a diagram of the first process of dirt sampling in this invention; Figure 6 This is a diagram of the second process of dirt sampling in this invention; Figure 7 This is a diagram of the third process of dirt sampling in this invention; Figure 8 This is a diagram of the fourth process of dirt sampling in this invention; Figure 9 This is a diagram of the fifth process of dirt sampling in this invention; Figure 10 This is a schematic diagram of the dirt cross-section of the present invention; Figure 11 This is a three-dimensional porosity photograph of the present invention.

[0026] Explanation of reference numerals in the attached figures: 10-Fouling reproduction device 100-Housing assembly, 101-Media flow channel, 102-Fast exhaust channel, 103-Media inlet, 104-Media outlet. 100′-pipe unit component 110 - Positioning grid, 120 - Hoop, 1201 - Hoop No. 1, 1202 - Hoop No. 2, 1203 - Hoop No. 3, 1204 - Hoop No. 4, 130 - First sealing seat assembly, 140 - Pressure bearing pipe, 1401 - Pressure bearing pipe No. 1, 1402 - Pressure bearing pipe No. 2, 1403 - Pressure bearing pipe No. 3, 150 - Second sealing seat assembly. 200 - Heating element; 201 - Dirt sample; 2011 - Dirt cross-section. 20-Switch valve, 30-Pressure regulator, 40-Heat exchanger, 50-Pump body, 60-Power supply, 70-Preheater. Detailed Implementation

[0027] The present invention will be further described below with reference to specific embodiments and accompanying drawings. More details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention can obviously be implemented in many other ways different from those described herein. Those skilled in the art can make similar extensions and derivations based on actual application situations without departing from the spirit of the present invention. Therefore, the scope of protection of the present invention should not be limited by the content of this specific embodiment.

[0028] It should be noted that these and other accompanying drawings are merely examples and are not drawn to scale, and should not be construed as limiting the scope of protection of the present invention.

[0029] The following is a combination of... Figures 1-3 This application introduces the fuel rod fouling reproduction system.

[0030] The fuel rod fouling reproduction system disclosed in this application includes a fouling reproduction device 10. The fouling reproduction device 10 includes a housing assembly 100 and a heating element 200. The housing assembly 100 is provided with a medium flow channel 101 for accommodating the heating element 200 and a quick discharge channel 102 communicating with the medium flow channel 101. The quick discharge channel 102 can be provided on a pipe unit 100' such as a pressure pipe 140, and the quick discharge channel 102 is provided with a switching valve 20 to control the switching timing. The medium flow channel 101 is used to introduce a fouling reproduction agent and accommodate the heating element 200, so that corrosive substances in the fouling reproduction agent can be deposited on the heating element 200.

[0031] The fouling reproducible agent in the shell assembly 100 has the same composition as the coolant in a pressurized water reactor. Specifically, the main component of the fouling reproducible agent is liquid water, and it also contains dissolved ions and suspended insoluble particles, including ions such as B, Li, Fe, and Ni, as well as NiFe2O4 particles. In a pressurized water reactor, the core function of the coolant is to participate in energy conversion and power generation; however, in this application, the fouling reproducible agent focuses on simulating the fouling deposition phenomenon that occurs during power generation in a nuclear power plant, and providing a corresponding hydrochemical environment for fouling formation and stripping, thereby conducting relevant mechanism research.

[0032] The heating element 200 simulates the fuel rods in a pressurized water reactor. It can simulate the heat generation process of nuclear fuel fission by applying a power source, thereby heating the fouling reproducible agent in the medium flow channel 101 to boiling point. This causes the corrosive substances in the fouling reproducible agent to deposit on the heating element 200, ultimately forming fouling. Specifically, the corrosive substances include ions such as B, Li, Fe, and Ni, as well as NiFe2O4 particles. During the boiling process of the fouling reproducible agent, B, Li, Fe, and Ni ions precipitate in compound form and deposit on the surface of the heating element 200 as fouling. For NiFe2O4 particles, which have reverse solubility, the heating process prevents them from dissolving and releasing into the fouling reproducible agent. The NiFe2O4 particles also gradually adsorb and settle on the surface of the heating element 200 through various processes, becoming part of the fouling.

[0033] By setting up the fast discharge channel 102, the fouling reproducing agent in the medium flow channel 101 can be discharged after the corrosive substances have been collected, thus avoiding the interference of long-term retention of the fouling reproducing agent on subsequent fouling sampling and characterization.

[0034] Furthermore, the housing assembly 100 includes a plurality of sequentially detachably connected tubular unit components 100', which are used for the medium flow channel 101 to pass through. The tubular unit components 100' are used to make the housing assembly 100 a detachable combined structure, which facilitates the cutting of multiple samples from the heating element 200. The specific method will be described in detail in the dirt sampling method below.

[0035] Furthermore, the housing assembly 100 also includes a positioning grid 110, with a gap reserved at the junction of adjacent tube unit components 100' for the outer edge of the positioning grid 110 to be engaged, and the inner edge of the positioning grid 110 located in the medium flow channel 101 to support and position the heating element 200.

[0036] Furthermore, the housing assembly 100 includes a sleeve 120, and adjacent pipe unit parts 100' are detachably connected by the sleeve 120, making the assembly and disassembly of the housing assembly 100 more convenient.

[0037] Furthermore, the pipe unit 100' is divided into a first sealing seat assembly 130, a pressure-bearing pipe 140, and a second sealing seat assembly 150. The medium flow channel 101 sequentially passes through the second sealing seat assembly 150, the pressure-bearing pipe 140, and the first sealing seat assembly 130. The conductive part of the heating element 200 extends out of the housing assembly 100 via the second sealing seat assembly 150. A conductive element connected to the heating element 200 is provided on the first sealing seat assembly 130. The first sealing seat assembly 130, the pressure-bearing pipe 140, and the second sealing seat assembly 150 together constitute a cavity that surrounds and covers the medium flow channel 101. At the same time, the first sealing seat assembly 130 and the second sealing seat assembly 150 seal both ends of the medium flow channel 101 to prevent leakage of the fouling reproducible agent when it flows through the medium flow channel 101.

[0038] Furthermore, the fouling reproducibility system also includes a heat exchanger 40 and a pump body 50. Meanwhile, the housing assembly 100 is provided with a medium inlet 103 on the second sealing seat assembly 150 and a medium outlet 104 on the first sealing seat assembly 130. The medium flow channel 101 is connected to the medium inlet 103 and the medium outlet 104 respectively, and the medium outlet 104 and the medium inlet 103 are interconnected to form a circulation loop for the fouling reproducibility agent. Both the heat exchanger 40 and the pump body 50 are located in the circulation loop of the fouling reproducibility agent.

[0039] The circulating loop enables dynamic migration of corrosion products on the shell assembly 100 and deposition on the heating element 200, effectively simulating the migration and deposition behavior of pressurized water reactor (PWR) corrosion products in the primary loop system. This helps researchers better understand the deposition patterns of PWR core corrosion products. The heat exchanger 40 simulates the steam generator in the primary loop of a PWR. The steam generator primarily transfers heat from the primary loop coolant to the secondary loop, ultimately lowering the coolant temperature. Based on this, the heat exchanger 40 is installed in the circulating loop for heat exchange and cooling. This ensures that the inlet and outlet temperatures of the heat exchanger 40 are the same as those of the steam generator in the PWR, better guaranteeing environmental consistency between the circulating loop and the PWR, and further helping researchers understand the deposition patterns of PWR core corrosion products. The pump body 50 is a variable frequency pump, providing the power required for the circulation of the fouling reproducible agent, allowing the agent, cooled by the heat exchanger 40, to re-enter the medium flow channel 101 through the medium inlet 103.

[0040] Furthermore, the dirt reproduction system also includes a power supply 60. The two poles of the power supply 60 are applied to both sides of the dirt collection section of the heating element 200 to form a conductive circuit. The dirt collection section is the part of the heating element 200 located in the housing assembly 100. Specifically, one pole of the power supply 60 is connected to one end of the dirt collection section of the heating element 200 via a conductive element on the first sealing seat assembly 130, and the other pole of the power supply 60 is connected to the conductive part of the heating element 200. This allows the two poles of the power supply 60 to be applied to both sides of the dirt collection section of the heating element 200 to form a conductive circuit, thereby achieving heating of the heating element 200.

[0041] Furthermore, power supply 60 is a low-voltage, high-current power supply. A low-voltage, high-current power supply refers to a power supply with a lower output voltage but a higher output current. This type of power supply usually adopts switching power supply technology and has the characteristics of high efficiency, stability, and safety. Power supply 60 has a built-in programmable control program, so power supply 60 can reduce power in a stepped manner or be directly shut down.

[0042] Furthermore, the fouling reproduction system also includes a pressure regulator 30, which is located in the circulation loop of the fouling reproduction agent. The pressure regulator 30 can be filled with inert gases such as argon to increase and stabilize the pressure of the fouling reproduction system.

[0043] Furthermore, the fouling re-enhancing system also includes a preheater 70, which is located in the circulation loop of the fouling re-enhancing agent. As mentioned above, the heat exchanger 40 cools the fouling re-enhancing agent. To prevent the fouling re-enhancing agent from flowing back into the medium channel 101 at a low temperature, the preheater 70 can be used to preheat the fouling re-enhancing agent before it is introduced into the medium channel 101. In this way, the preheater 70, in conjunction with the heat exchanger 40, can regulate the temperature of the fouling re-enhancing agent at the inlet of the medium channel 101, ensuring that the temperature at the inlet of the core medium channel 101 is the same as that of the pressurized water reactor. This better ensures the consistency of the circulation loop with the environment in the pressurized water reactor, and can better help researchers understand the patterns related to the deposition of corrosion products in the pressurized water reactor core.

[0044] The method for sampling fouling from fuel rods in this application is described below.

[0045] Step S1: Pressurize the medium flow channel 101 to a preset pressure and introduce a fouling reproducibility agent into the medium flow channel 101, wherein the preset pressure is greater than atmospheric pressure by 1.01325 × 10⁻⁶. 5 The preset pressure can be adjusted by the voltage regulator 30, for example, the preset pressure is 15.4 MPa.

[0046] Step S2: Heat the dirt reproducing agent to boiling point through the heating element 200 so that the corrosion products in the dirt reproducing agent are deposited on the heating element 200.

[0047] Step S3: Turn off the pump body 50, heat exchanger 40 and power supply 60. Turning off the pump body 50 can prevent overpressure in the circuit, turning off the heat exchanger 40 can save energy, and turning off the power supply 60 can prevent the heating element 200 from being continuously heated and overheated and damaged.

[0048] Step S4: Open the switch valve 20 to discharge the fouling reproducing agent in the housing assembly 100 through the quick discharge channel 102. Here, the switch valve 20 on the quick discharge channel 102 near the medium outlet 104 and the switch valve 20 on the quick discharge channel 102 near the medium inlet 103 can be opened simultaneously as needed to fully discharge the fouling reproducing agent; alternatively, only the switch valve 20 on the quick discharge channel 102 near the medium outlet 104 can be opened so that the fouling reproducing agent is discharged only from the top of the housing assembly 100.

[0049] Step S5: Separate the dirt reproduction device 10 from the dirt reproduction system.

[0050] Step S6, performing the sample collection process, including: collecting the heating element 200 in the medium flow channel 101 that has deposited corrosion to obtain a dirt collection sample 201.

[0051] As can be seen, due to the pressurization of the medium flow channel 101 to the preset pressure, the shell assembly 100 is kept under high pressure during the fouling process. Thus, when the fouling is collected on the heating element 200 and the switch valve 20 is opened, the high pressure inside the shell assembly 100 will force the fouling reproduction agent to be discharged quickly through the fast discharge channel 102. This avoids significant changes in the composition and porous structure of the fouling sample 201 when it is taken out or after a series of operations such as transfer, cooling, storage and radioactivity removal. In particular, it avoids the re-dissolving of NiFe2O4, which has reverse solubility, back into the fouling reproduction agent, thereby ensuring that the analysis results are representative of the corrosion product deposits in the actual reactor.

[0052] Optionally, step S6 includes: Step S61: Remove one tube unit 100' to partially expose the heating element 200; Step S62: Cut off the exposed part of the heating element 200 to obtain a dirt collection sample 201.

[0053] Return to step S61 to remove the next pipe unit 100', until all pipe unit 100's are removed.

[0054] In this way, by segmenting the heating element 200 to obtain multiple dirt collection samples 201, it is convenient to store and retrieve the samples, and avoids the problem of samples being too long to store and transport. Furthermore, the analysis results of multiple dirt collection samples 201 can be mutually verified, further improving the accuracy of the analysis, so that the analysis results can better reflect the representative corrosion product deposit layer in the actual reactor.

[0055] Furthermore, step S61 also includes: exposing the positioning grid 110 at the position corresponding to the removed pipe unit 100′; Step S6 also includes step S63: removing the exposed positioning grid 110.

[0056] This avoids scratching the dirt on the positioning grid 110 during the sampling process, preserves the integrity of the dirt on the sample 201 to the greatest extent, and further ensures that the analysis results are representative of the corrosion product deposits in the actual reactor.

[0057] Furthermore, step S61 also includes: removing the clamp 120.

[0058] Furthermore, to facilitate sampling, the dirt collection sample 201 should be cut into segments in a certain order. For example, the dirt collection sample 201 can be cut into segments from the first sealing seat assembly 130 to the second sealing seat assembly 150, or from the second sealing seat assembly 150 to the first sealing seat assembly 130.

[0059] Further, step S1 includes: preheating by preheater 70 to introduce a fouling reproducible agent at a first preset temperature into medium flow channel 101, such as the first preset temperature being 300°C to 310°C.

[0060] Step S2 includes: heating the dirt reproducing agent to a second preset temperature through the heating element 200. The second preset temperature is greater than or equal to the first preset temperature. For example, the second preset temperature near the medium outlet 104 is 320°C to 330°C, and the second preset temperature near the medium inlet 103 is 310°C to 320°C.

[0061] In this way, the preheater 70, together with the heating element 200, effectively ensures the temperature that the system can reach, thereby effectively simulating the thermal parameter environment of the fuel rods in a real pressurized water reactor.

[0062] In summary, the fuel rod fouling sampling method has the following main advantages: Firstly, during the fouling collection process, the shell assembly 100 maintains a high-pressure state. When the fouling is collected on the heating element 200 and the switch valve 20 is opened, the high-pressure state inside the shell assembly 100 forces the fouling reproduction agent to be quickly discharged through the fast discharge channel 102. This avoids significant changes in the composition and porous structure of the fouling sample 201 when it is taken out or after a series of operations such as transfer, cooling, storage, and radioactivity removal. In particular, it avoids the re-dissolving of NiFe2O4, which has reverse solubility, back into the fouling reproduction agent, thereby ensuring that the analysis results are representative of the corrosion product deposits in the actual reactor.

[0063] Secondly, by segmenting the heating element 200 to obtain multiple dirt collection samples 201, it is not only convenient to store and retrieve the samples, but also avoids the problem of the samples being too long to store and transport. Furthermore, the analysis results of multiple dirt collection samples 201 can be mutually verified, further improving the accuracy of the analysis, so that the analysis results can better reflect the representative corrosion product deposit layer in the actual reactor.

[0064] Thirdly, during the process of the heating element 200 segmentally cutting off the dirt collection sample 201, the positioning grid 110 can avoid scratching the dirt, thus preserving the integrity of the dirt on the dirt collection sample 201 to the greatest extent, and further ensuring that the analysis results have a representative corrosion product deposition layer in the actual reactor.

[0065] The following describes the fuel rod fouling characterization method of this application.

[0066] The fouling characterization method of this application is used to characterize the fouling sample 201 obtained in the fouling sampling method of steps S1 to S6. The fouling characterization method includes step S7: obtaining the three-dimensional porosity of the fouling sample 201.

[0067] Further, step S7 includes: Several dirt cross sections 2011 were obtained on the dirt collection sample 201, and the porosity of each dirt cross section 2011 was obtained, specifically as follows: Figure 10 As shown.

[0068] Based on several dirt cross-sections and the porosity of each dirt cross-section, the three-dimensional porosity of the dirt collection sample 201 was obtained, specifically as follows: Figure 11 As shown.

[0069] The overall operation process for dirt sampling and dirt characterization of this application will be described below based on the foregoing embodiments.

[0070] The overall operational procedures for dirt sampling and characterization are both designed for... Figure 4 This section introduces a dirt reproduction device, for reference. Figure 4 From upstream to downstream, the housing assembly 100 is sequentially provided with a second sealing seat assembly 150, a pressure-bearing pipe 140, and a first sealing seat assembly 130. Three pressure-bearing pipes 140 are provided, designated as pressure-bearing pipe 1401 to pressure-bearing pipe 1403. Four clamps 120 are provided: clamp 1201 located between an adjacent first sealing seat assembly 130 and pressure-bearing pipe 1401; clamp 1202 located between pressure-bearing pipe 1401 and pressure-bearing pipe 1402; clamp 1203 located between pressure-bearing pipe 1402 and pressure-bearing pipe 1403; and clamp 1203 located between pressure-bearing pipe 1403 and pressure-bearing pipe 1403. The sealing seat assembly 150 includes a fourth clamp 1204; four positioning grids 110 are provided, namely the first positioning grid to the fourth positioning grid, which correspond one-to-one with the first clamp 1201 to the fourth clamp 1204; the first sealing seat assembly 130 fixes and seals one end of the dirt collection part, and the second sealing seat assembly 150 fixes and seals the other end of the dirt collection part, which is the part of the heating element 200 located in the housing assembly 100.

[0071] Figure 5 This is a diagram of the first process of dirt sampling in this invention; Figure 6 This is a diagram of the second process of dirt sampling in this invention; Figure 7 This is a diagram of the third process of dirt sampling in this invention; Figure 8 This is a diagram of the fourth process of dirt sampling in this invention; Figure 9 This is a diagram of the fifth process of dirt sampling in this invention; see reference. Figure 1 , Figures 4-9 Sampling is performed in the direction from the first sealing seat assembly 130 to the second sealing seat assembly 150, targeting Figure 4 The overall procedure for sampling dirt from the heating element 200 is as follows: Step S1: Pressurize the medium flow channel 101 to a preset pressure, and introduce a fouling reproducible agent with a first preset temperature into the medium flow channel 101. Specifically, by injecting argon gas into the pressure regulator 30, the entire fouling reproducible system is pressurized to a preset pressure of 15.4 MPa, and preheated by the preheater 70, a fouling reproducible agent with a first preset temperature of 300°C~310°C is introduced into the medium flow channel 101, as detailed below. Figure 1 As shown.

[0072] Step S2: The fouling reproducible agent is heated to a second preset temperature by the heating element 200, so that the corrosive substances in the fouling reproducible agent are deposited on the heating element 200. The second preset temperature near the medium outlet 104 is 320℃~330℃, and the second preset temperature near the medium inlet 103 is 310℃~320℃. Specifically, the heating element 200 simulates the fuel rods in a pressurized water reactor. The heating element 200 can simulate the process of nuclear fuel fission heat generation by applying a power supply 60, thereby heating the fouling reproducible agent in the medium flow channel 101 to boiling, so that the corrosive substances in the fouling reproducible agent are deposited on the heating element 200, and finally fouling is formed on the heating element 200. The corrosion products, including the aforementioned B, Li, Fe, Ni ions and NiFe2O4 particles, precipitate as compounds during the boiling process of the fouling reproducible agent and deposit as fouling on the surface of the heating element 200. For NiFe2O4 particles, which have reverse solubility, the heating process prevents them from dissolving and releasing into the fouling reproducible agent. The NiFe2O4 particles also gradually adsorb and settle onto the surface of the heating element 200 through various processes, forming part of the fouling. Thus, the preheater 70, in conjunction with the heating element 200, effectively ensures the system's achievable temperature, thereby effectively simulating the thermal parameters of a real pressurized water reactor fuel rod.

[0073] Step S3: Turn off the pump body 50, heat exchanger 40, and power supply 60, and close the switch valve 20 on the quick discharge channel 102 near the medium inlet 103. Turning off the pump body 50 prevents overpressure in the circuit, turning off the heat exchanger 40 saves energy, and turning off the power supply 60 prevents the heating element 200 from being continuously heated and overheated, causing damage.

[0074] Step S4: Open the switch valve 20 on the quick discharge channel 102 near the medium outlet 104 to quickly discharge the dirt regeneration agent in the housing assembly 100 under high pressure.

[0075] Step S5: After the dirt reproduction agent is discharged, disconnect the circulation loop and conductive loop of the dirt reproduction agent, thereby separating the dirt reproduction device 10 from the dirt reproduction system.

[0076] Step S6: Extract a sample of the heating element 200 from the medium flow channel 101 to obtain a dirt collection sample 201; specifically, follow these steps: Combination Figure 4 As shown, firstly, following steps S61-1 to S63-3, a section of the heating element 200 covered by the first sealing seat assembly 130 is cut off as a dirt collection sample 201. Steps S61-1 to S63-3 are performed in accordance with the above steps S61 to S63, including: Step S61-1: Remove the sleeve 120 (i.e., the first sleeve 1201) connecting the first sealing seat assembly 130, and disassemble each component of the first sealing seat assembly 130 to release the fixation on the dirt collection end of the heating element 200, and to partially expose the heating element 200 that is covered by the first sealing seat assembly 130, and to expose the positioning grid 110 (i.e., the first positioning grid) that is covered by the first sealing seat assembly 130. Step S62-1: Cut off the exposed part of the heating element 200 to use the obtained dirt collection sample 201 as the #1 dirt collection sample. Cutting can be done using equipment such as an angle grinder. Step S63-1: Remove the exposed positioning grid 110 (positioning grid No. 1); the method of first removing the dirt collection sample 201 and then removing the positioning grid 110 can avoid scratching the dirt on the dirt collection sample 201. Then, following steps S61-2 to S63-2, S61-3 to S63-3, and S61-4 to S63-4, the portion of the heating element 200 covered by the pressure-bearing tube 140 is cut off as a sample 201 of dirt. Steps S61-2 to S63-2, S61-3 to S63-3, and S61-4 to S63-4 are all performed in accordance with the above steps S61 to S63, including: Step S61-2: Remove the second clamp 1202 corresponding to the first pressure-bearing pipe 1401, and remove the first pressure-bearing pipe 1401, so that the heating element 200 covered by the first pressure-bearing pipe 1401 is partially exposed, and the second positioning grid covered by the first pressure-bearing pipe 1401 is exposed, as follows: Figures 4-7 As shown; Step S62-2: The exposed portion of the heating element 200 is cut off, and the obtained dirt collection sample 201 is used as the #2 dirt collection sample, specifically as follows... Figure 8 As shown; Step S63-2: Remove the exposed second positioning grid, specifically as follows: Figure 9 As shown; Step S61-3: Remove the No. 3 clamp 1203 corresponding to the No. 2 pressure pipe 1402 and remove the No. 2 pressure pipe 1402 to expose the heating element 200 that was covered by the No. 2 pressure pipe 1402 and expose the No. 3 positioning grid that was covered by the No. 2 pressure pipe 1402. Step S62-3: Cut off the exposed part of the heating element 200 to use the obtained dirt collection sample 201 as the #3 dirt collection sample; Step S63-3: Remove the exposed No. 3 positioning grid; Step S61-4: Remove the No. 4 clamp 1204 corresponding to the No. 3 pressure pipe 1403 and remove the No. 3 pressure pipe 1403 so that the heating element 200 covered by the No. 3 pressure pipe 1403 is partially exposed, and the No. 4 positioning grid covered by the No. 3 pressure pipe 1403 is exposed. Step S62-4: Cut off the exposed part of the heating element 200 to use the obtained dirt collection sample 201 as #4 dirt collection sample; Step S63-4: Remove the exposed No. 4 positioning grid; Finally, following steps S61-5 to S62-5, the portion of the heating element 200 covered by the second sealing seat assembly 150 is cut off as a dirt collection sample 201. Steps S61-5 to S62-5 are performed in accordance with steps S61 to S62 above, including: Step S61-5: Disassemble each component of the second sealing seat assembly 150 to release the fixation on the dirt collection end of the heating element 200 and to partially expose the heating element 200 that is covered by the second sealing seat assembly 150. Step S62-5: Cut off the exposed part of the heating element 200 to use the obtained dirt collection sample 201 as #5 dirt collection sample.

[0077] Thus, a total of five dirt collection samples 201 were obtained, from #1 to #5. Each dirt collection sample 201 has a porous dirt layer on the outside and a shell substrate on the inside. Then, step S64 was performed, in which the ends of the #1 to #5 dirt collection samples were precisely cut using methods such as wire cutting to make the end faces of the dirt collection samples 201 flat.

[0078] Figure 10 This is a schematic diagram of the dirt cross-section of the present invention; Figure 11 This is a three-dimensional porosity photograph of the present invention, for reference. Figure 10 and Figure 11 The #1 to #5 dirt samples obtained in steps S1 to S6 above are characterized. The overall characterization process is carried out according to step S7, which includes: Step S71: The porous dirt layer of the dirt collection sample 201 is bombarded with a polyion beam 1000 to obtain the dirt cross-section 2011, as shown in the following figure. Figure 10 As shown; Step S72: Use an electron scanning microscope 2000 to photograph the cross-section 2011 of the dirt to obtain the porosity of the dirt cross-section; Step S73: Return to step S71 until a preset number of dirt cross sections 2011 are obtained, and the porosity of each dirt cross section 2011 is obtained; Step S75: Based on several dirt cross-sections and the porosity of each dirt cross-section, obtain the three-dimensional porosity of the dirt collection sample 201, specifically as follows: Figure 11 As shown.

[0079] While the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the invention. Any variations and modifications can be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, any modifications, equivalent changes, and alterations made to the above embodiments based on the technical essence of the present invention, without departing from the scope of the invention, fall within the protection scope defined by the claims of the present invention.

Claims

1. A method of soil sampling for obtaining a soil collection sample (201) from a soil reproducing system, characterized in that, The fouling reproduction system includes a fouling reproduction device (10); the fouling reproduction device (10) includes a housing assembly (100) and a heating element (200), the housing assembly (100) is provided with a medium flow channel (101) for accommodating the heating element (200), and a quick-drain channel (102) communicating with the medium flow channel (101), the medium flow channel (101) is used to introduce a fouling reproduction agent and accommodate the heating element (200), so that the corrosive substances in the fouling reproduction agent are deposited on the heating element (200); the housing assembly (100) also includes a plurality of sequentially detachably connected pipe unit components (100'), the plurality of pipe unit components (100') are used for the medium flow channel (101) to pass through; The method includes: The medium flow channel (101) is pressurized to a preset pressure, and a dirt regeneration agent is introduced into the medium flow channel (101), wherein the preset pressure is greater than atmospheric pressure; The dirt reproducing agent is heated by the heating element (200) to cause the corrosive substances in the dirt reproducing agent to deposit on the heating element (200). The fouling reproducing agent in the housing assembly (100) is discharged through the quick discharge channel (102); Performing a sample cutting process, the sample cutting process includes: Remove one tube unit (100') to partially expose the heating element (200); The exposed portion of the heating element (200) is cut off to obtain a dirt collection sample (201).

2. The method of claim 1, wherein, The housing assembly (100) also includes a positioning grid (110), and the junction of adjacent tubular unit components (100') is reserved with a gap for the outer edge of the positioning grid (110) to be engaged; The removal of a tube unit (100') to partially expose the heating element (200) further includes exposing the positioning grid (110) at the corresponding position of the removed tube unit (100'); The sample cutting process further includes: removing the exposed positioning grid (110).

3. The method of claim 1, wherein, After the portion of the heating element (200) exposed is cut off to obtain a dirt collection sample (201), the sample cutting process further includes: The end of the dirt collection sample (201) was cut.

4. The method of claim 1, wherein, The housing assembly (100) includes a hoop (120), and adjacent pipe unit components (100') are detachably connected by the hoop (120); The removal of a tube unit (100') to partially expose the heating element (200) also includes removing the clamp (120).

5. The method of claim 4, wherein, The pipe unit (100') is divided into a first sealing seat assembly (130), a pressure-bearing pipe (140), and a second sealing seat assembly (150). The medium flow channel (101) sequentially enters the second sealing seat assembly (150), the pressure-bearing pipe (140), and the first sealing seat assembly (130). The sample cutting process also includes: The dirt collection sample (201) is segmented from the first sealing seat assembly (130) to the second sealing seat assembly (150), or from the second sealing seat assembly (150) to the first sealing seat assembly (130).

6. The method of claim 1, wherein, The fouling reproduction system further includes a heat exchanger (40) and a pump body (50). The shell assembly (100) is provided with a medium inlet (103) and a medium outlet (104) that connect to the medium flow channel (101). The medium outlet (104) and the medium inlet (103) are interconnected to form a circulation loop of the fouling reproduction agent. The heat exchanger (40) and the pump body (50) are both located in the circulation loop of the fouling reproduction agent. Before discharging the fouling reproducing agent from the housing assembly (100) through the quick-drain channel (102), the method further includes: The pump body (50) and the heat exchanger (40) are shut down.

7. The method of claim 6, wherein, The dirt reproduction system also includes a power supply (60), the two poles of which are loaded on both sides of the dirt collection part of the heating element (200) to form a conductive circuit. The dirt collection part is the part of the heating element (200) located in the housing assembly (100). Before discharging the dirt reproducing agent in the housing assembly (100) through the quick discharge channel (102), the method further includes turning off the power supply (60).

8. The method of claim 5, wherein, The step of pressurizing the medium flow channel (101) to a preset pressure and introducing a fouling reproducibility agent into the medium flow channel (101) includes: A fouling reproducible agent at a first preset temperature is introduced into the medium flow channel (101); The step of heating the dirt reactivator through the heating element (200) to cause corrosion products in the dirt reactivator to deposit on the heating element (200) includes: The dirt reproducing agent is heated to a second preset temperature by the heating element (200), the second preset temperature being greater than or equal to the first preset temperature.

9. A method for characterizing a fouling sample (201) obtained by the method for sampling fouling according to any one of claims 1 to 8, characterized in that, The method includes: Obtain several dirt cross sections on the dirt collection sample (201), and obtain the porosity of each dirt cross section; Based on several dirt cross sections and the porosity of each dirt cross section, the three-dimensional porosity on the dirt collection sample (201) is obtained.

Images